Debt - Additional Information (Details)

v3.22.4

Debt - Additional Information (Details)									12 Months Ended
		Jan. 13, 2023 USD ($)	Jan. 13, 2023 USD ($)	Feb. 22, 2022 USD ($)	Jan. 20, 2022 USD ($)	Sep. 16, 2021 USD ($)	Mar. 04, 2021 USD ($)	Oct. 27, 2020 USD ($)	Dec. 31, 2022 USD ($) Firm	Dec. 31, 2021 USD ($) Firm	Dec. 31, 2020 USD ($)	Jun. 23, 2022 USD ($)	Jun. 22, 2022 USD ($)	Feb. 01, 2022 USD ($) shares	Nov. 04, 2020 USD ($)	Jun. 03, 2020 USD ($)	Feb. 05, 2020 USD ($)	Jul. 16, 2019 USD ($)	Sep. 24, 2018 USD ($)	Oct. 23, 2017 USD ($)	Jan. 25, 2017 USD ($)
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 2,185,000,000	$ 1,745,000,000
Repayment of debt									931,198,000	1,787,043,000	$ 827,405,000
Debt issuance costs									22,642,000	16,035,000
Restricted cash (amounts related to a VIE $8,346 and $0, respectively)									$ 10,079,000	3,150,000	39,340,000
Line of credit facility, termination date									Nov. 09, 2026
Investments at Fair Value									$ 2,963,955,000	2,434,522,000
Loss on extinguishment of debt									$ (3,686,000)	(4,419,000)	$ 0
Line of Credit Facility, Description									Availability under the SMBC Facility will terminate on November 7, 2025, and the outstanding loans under the SMBC Facility will mature on November 9, 2026.
Secured Credit Facility with M U F G Bank Ltd. (M U F G) [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Covenant Terms			(vi) modify the minimum tangible net worth covenant to an amount that is in excess of $869.0 million.
Line of credit facility, termination date		Jan. 13, 2026
Interest rate plus applicable margin adjustment		2.75%
Secured Credit Facility with M U F G Bank Ltd. (M U F G) [Member] | Minimum | Subsequent Event [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 400,000,000.0	$ 400,000,000.0
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.75%
Secured Credit Facility with M U F G Bank Ltd. (M U F G) [Member] | Maximum
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 545,000,000.0	545,000,000.0						$ 545,000,000.0
Secured Credit Facility with M U F G Bank Ltd. (M U F G) [Member] | Maximum | Subsequent Event [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 600,000,000.0	600,000,000.0
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.375%
MUFG Bank Facility
Debt Instrument [Line Items]
Line of credit facility, termination date									Feb. 22, 2024
Line of Credit Facility, Description									The MUFG Bank Facility contains an accordion feature, in which the Company can increase the credit line up to an aggregate of $600.0 million, funded by existing or additional lenders and with the agreement of MUFG Bank and subject to other customary conditions.
MUFG Bank Facility | Lender [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity										400,000.0
MUFG Bank Facility | Minimum
Debt Instrument [Line Items]
Maximum borrowing capacity									$ 545,000,000.0
MUFG Bank Facility | Maximum
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 600,000,000.0	$ 600,000,000.0
MUFG Bank Facility | One-month interest period
Debt Instrument [Line Items]
Interest rate plus applicable margin adjustment									2.60%
MUFG Bank Facility | Three-month interest period
Debt Instrument [Line Items]
Interest rate plus applicable margin adjustment									2.65%
SMBC Facility
Debt Instrument [Line Items]
Line of credit facility, termination date									Nov. 07, 2025
Maximum borrowing capacity									$ 225,000,000.0
Line of Credit Facility, Description									the SMBC Facility provides for the issuance of letters of credit on the account of the Company or its designee in U.S. dollars and certain agreed upon foreign currencies in an aggregate face amount not to exceed $15.0 million.
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage									0.375%
SMBC Facility | Subsequent Event [Member]
Debt Instrument [Line Items]
Commitment amount		$ 100,000,000.0
SMBC Facility | Minimum
Debt Instrument [Line Items]
Interest rate plus applicable margin adjustment									0.875%
SMBC Facility | Maximum
Debt Instrument [Line Items]
Interest rate plus applicable margin adjustment									2.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt average amount outstanding									$ 127,700,000	$ 28,800,000
Line of credit interest rate									4.51%	2.54%
SBA Debentures
Debt Instrument [Line Items]
Debt Instrument Face Amount	[1]								$ 175,000,000	$ 175,000,000
Debt issuance costs									5,262,000	5,002,000
2022 Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 0	150,000,000										$ 150,000,000.0
Debt instrument, interest rate									4.625%
Debt Instrument Maturity Date									Oct. 23, 2022
Debt issuance costs									$ 0	300,000
Debt Instrument, redemption, description									On October 23, 2017, the Company issued $150.0 million in aggregate principal amount of 4.625% interest-bearing unsecured notes that mature on October 23, 2022 (the “2022 Notes”), unless repurchased in accordance with their terms.
Repayment of debt				$ 150,000,000.0
Interest payable				2,300,000
2022 Notes | Prepayment Fees [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt				3,300,000
2022 Notes | Debt Issuance Cost [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt				$ 300,000
2022 Convertible Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 0	230,000,000											$ 230,000,000.0
Debt instrument, interest rate									4.375%
Debt Instrument Maturity Date									Feb. 01, 2022
Debt issuance costs									$ 0	149,000
Debt Instrument, redemption, description									On January 25, 2017, the Company issued $230.0 million in aggregate principal amount of 4.375% interest-bearing unsecured notes due on February 1, 2022 (the “2022 Convertible Notes”), unless previously converted or caused to repurchase the notes in accordance with their terms by the holders of the 2022 Convertible Notes.
Repayment of debt														$ 230,000,000.0
Interest payable														$ 5,000,000.0
Convertible Debt Redemption Shares Issued on Redemption | shares														981,169
2022 Convertible Notes | Additional Face Amount [Member]
Debt Instrument [Line Items]
Debt Instrument Face Amount																					$ 30,000,000.0
July 2024 Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 105,000,000	105,000,000								$ 105,000,000.0
Debt instrument, interest rate									4.77%
Debt Instrument Maturity Date									Jul. 16, 2024
Debt issuance costs									$ 467,000	762,000
Debt instrument, payment terms, description									Interest on the July 2024 Notes is due semiannually.
Debt Instrument, redemption, description									On July 16, 2019, the Company issued $105.0 million in aggregate principal amount of 4.77% interest-bearing unsecured notes due on July 16, 2024 (the “July 2024 Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering.
Debt Instrument, Collateral									The July 2024 Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company.
February 2025 Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 50,000,000	50,000,000							$ 50,000,000.0
Debt instrument, interest rate									4.28%
Debt Instrument Maturity Date									Feb. 05, 2025
Debt issuance costs									$ 249,000	363,000
Debt instrument, payment terms, description									Interest on the February 2025 Notes is due semiannually.
Debt Instrument, redemption, description									On February 5, 2020, the Company issued $50.0 million in aggregate principal amount of 4.28% interest-bearing unsecured notes due February 5, 2025 (the “February 2025 Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering.
Debt Instrument, Collateral									The February 2025 Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company.
June 2025 Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 70,000,000	70,000,000						$ 70,000,000.0
Debt instrument, interest rate									4.31%
Debt Instrument Maturity Date									Jun. 03, 2025
Debt issuance costs									$ 405,000	567,000
Debt instrument, payment terms, description									Interest on the June 2025 Notes is due semiannually.
Debt Instrument, redemption, description									On June 3, 2020, the Company issued $70.0 million in aggregate principal amount of 4.31% interest-bearing unsecured notes due June 3, 2025 (the “June 2025 Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering pursuant to the June 2025 Notes indenture.
Debt Instrument, Collateral									The June 2025 Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company.
June 2025 3-Year Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 50,000,000	0		$ 50,000,000.0
Debt instrument, interest rate									6.00%
Debt Instrument Maturity Date									Jun. 23, 2025
Debt issuance costs									$ 384,000	0
Debt instrument, payment terms, description									Interest on the June 2025 3-Year Notes is due semiannually.
Debt Instrument, redemption, description									On June 23, 2022, the Company issued $50.0 million in aggregate principal amount of 6.00% interest-bearing unsecured notes due June 23, 2025 (the “June 2025 3-Year Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering.
Debt Instrument, Collateral									The June 2025 3-Year Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company.
March 2026 A Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 50,000,000	50,000,000					$ 50,000,000.0
Debt instrument, interest rate									4.50%
Debt Instrument Maturity Date									Mar. 04, 2026
Debt issuance costs									$ 300,000	395,000
Debt instrument, payment terms, description									Interest on the March 2026 A Notes is due semiannually.
Debt Instrument, redemption, description									On November 4, 2020, the Company issued $50.0 million in aggregate principal amount of 4.5% interest-bearing unsecured notes due March 4, 2026 (the “March 2026 A Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement notes offering.
Debt Instrument, Collateral									The March 2026 A Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated
March 2026 B Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount							$ 50,000,000.0		$ 50,000,000	50,000,000
Debt instrument, interest rate									4.55%
Debt Instrument Maturity Date									Mar. 04, 2026
Debt issuance costs									$ 327,000	430,000
Debt instrument, payment terms, description									Interest on the March 2026 B Notes is due semiannually.
Net proceeds from sale of Notes							49,500,000
Debt Instrument, redemption, description									On March 4, 2021, the Company issued $50.0 million in aggregate principal amount of 4.55% interest-bearing unsecured notes due March 4, 2026 (the “March 2026 B Notes”), unless repurchased in accordance with their terms, to qualified institutional investors in a private placement pursuant note offering.
Debt Instrument, Collateral									The March 2026 B Notes are general unsecured obligations of the Company that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by the Company.
Aggregate Debt Issuance Cost							$ 500,000
September 2026 Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount						$ 325,000,000.0			$ 325,000,000	325,000,000
Debt instrument, interest rate									2.625%
Debt Instrument Maturity Date									Sep. 16, 2026
Debt issuance costs									$ 3,642,000	4,624,000
Debt instrument, payment terms, description									Interest on the September 2026 Notes is payable semi-annually in arrears on March 16 and September 16 of each year, commencing on March 16, 2022.
Net proceeds from sale of Notes						320,100,000
Debt Instrument, Collateral									The September 2026 Notes are general unsecured obligations and rank pari passu, or equally in right of payment, with all outstanding and future unsecured unsubordinated indebtedness issued by the Company. The Company may redeem some or all of the September 2026 Notes at any time, or from time to time, at the redemption price set forth under the terms of the September 2026 Notes Indenture.
Aggregate Debt Issuance Cost						4,100,000
Aggregate Discount On Issuance						$ 800,000
January 2027 Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount					$ 350,000,000.0				$ 350,000,000	0
Debt instrument, interest rate									3.375%
Debt Instrument Maturity Date									Jan. 20, 2027
Debt issuance costs									$ 5,396,000	0
Debt instrument, payment terms, description									Interest on the January 2027 Notes is payable semi-annually in arrears on January 20 and July 20 of each year, commencing on July 20, 2022.
Net proceeds from sale of Notes					343,400,000
Debt Instrument, redemption, description									The Company may redeem some or all of the January 2027 Notes at any time, or from time to time, at the redemption price set forth under the terms of the January 2027 Notes Indenture.
Debt Instrument, Collateral									The January 2027 Notes are general unsecured obligations and rank pari passu, or equally in right of payment, with all outstanding and future unsecured unsubordinated indebtedness issued by the Company.
Aggregate Debt Issuance Cost					4,100,000
Aggregate Discount On Issuance					$ 2,500,000
2031 Asset-Backed Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 150,000,000	0			$ 150,000,000.0
Debt instrument, interest rate									4.95%
Debt Instrument Maturity Date									Jul. 20, 2031
Debt issuance costs									$ 2,043,000	0
Debt instrument, payment terms, description									Interest on the 2031 Asset-Backed Notes will be paid, to the extent of funds available.
Restricted cash (amounts related to a VIE $8,346 and $0, respectively)									$ 10,100,000	0
2033 Notes
Debt Instrument [Line Items]
Debt Instrument Face Amount									$ 40,000,000	40,000,000									$ 40,000,000.0
Debt instrument, interest rate									6.25%
Debt Instrument Maturity Date									Oct. 30, 2033
Debt issuance costs									$ 1,174,000	1,282,000
Debt instrument, payment terms, description									Interest on the 2033 Notes is payable quarterly in arrears on January 30, April 30, July 30, and October 30 of each year.
Debt Instrument, redemption, description									The Company may redeem some or all of the 2033 Notes at any time, or from time to time, at the redemption price set forth under the terms of the 2033 Notes indenture after October 30, 2023.
SMBC Facility
Debt Instrument [Line Items]
Debt Instrument Face Amount	[2]								$ 225,000,000	100,000,000
Debt issuance costs	[3]								1,701,000	922,000
Maximum borrowing capacity										$ 100,000,000.0
Foreign Currency Borrowing Member | SMBC Facility | Maximum
Debt Instrument [Line Items]
Maximum borrowing capacity									15,000,000.0
HC IV
Debt Instrument [Line Items]
License term								10 years
Regulatory capital commitment amount								$ 87,500,000
Debt Instrument Face Amount									$ 175,000,000.0
Investments held by number of companies | Firm									21	15
Percentage of total investment portfolio									11.60%	10.00%
Percentage of total assets held									11.50%	9.50%
Maximum borrowing capacity								$ 175,000,000.0
Debt Instrument License Description									HC IV received its license to operate as a SBIC on October 27, 2020. The license has a 10-year term.
Investments at Fair Value									$ 343,700,000	$ 244,500,000
Tangible assets									$ 348,600,000	$ 245,700,000
[1] Availability subject to the Company meeting the borrowing base requirements. [2] The June 2022 amendment of the MUFG Bank Facility replaced the Union Bank Facility via an amendment which changed the lead lender. [3] The MUFG Bank Facility (f.k.a. Union Bank Facility) and SMBC Facility, are line-of-credit arrangements, the debt issuance costs associated with these instruments are included within Other assets on the Consolidated Statements of Assets and Liabilities in accordance with ASC Subtopic 835-30