Quarterly report pursuant to Section 13 or 15(d)

Fair Value of Financial Instruments - Schedule of Fair Value Hierarchy Of Outstanding Borrowings (Details)

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Fair Value of Financial Instruments - Schedule of Fair Value Hierarchy Of Outstanding Borrowings (Details) - USD ($)
$ in Thousands
Sep. 30, 2023
Dec. 31, 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) $ 1,632,738 $ 1,574,351
Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 1,632,738 1,574,351
Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 1,487,649 1,434,445
SBA Debentures | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 170,175 169,738
SBA Debentures | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 148,274 155,257
July 2024 Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 104,754 104,533
July 2024 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 102,783 102,019
February 2025 Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 49,837 49,751
February 2025 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 47,443 47,044
June 2025 Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 69,717 69,595
June 2025 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 66,096 64,198
June 2025 3-Year Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 49,732 49,616
June 2025 3-Year Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 48,541 47,528
March 2026 A Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 49,771 49,700
March 2026 A Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 45,482 45,512
March 2026 B Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 49,751 49,673
March 2026 B Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 45,537 45,588
September 2026 Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 322,094 321,358
September 2026 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 273,407 269,509
January 2027 Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 345,602 344,604
January 2027 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 298,106 296,826
2031 Asset-Backed Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 148,397 147,957
2031 Asset-Backed Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 139,500 142,620
2033 Notes | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 38,908 38,826
2033 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 38,480 39,344
MUFG Bank Facility | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 61,000 107,000
MUFG Bank Facility | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 61,000 107,000
SMBC Facility | Carrying Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Debt (net of debt issuance costs - Note 5; amounts related to a VIE $147,663 and $0, respectively) 173,000 72,000
SMBC Facility | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 173,000 72,000
Observable Inputs (Level 2) | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 177,980 181,964
Observable Inputs (Level 2) | 2031 Asset-Backed Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 139,500 142,620
Observable Inputs (Level 2) | 2033 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 38,480 39,344
Unobservable Inputs (Level 3) | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 1,309,669 1,252,481
Unobservable Inputs (Level 3) | SBA Debentures | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 148,274 155,257
Unobservable Inputs (Level 3) | July 2024 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 102,783 102,019
Unobservable Inputs (Level 3) | February 2025 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 47,443 47,044
Unobservable Inputs (Level 3) | June 2025 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 66,096 64,198
Unobservable Inputs (Level 3) | June 2025 3-Year Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 48,541 47,528
Unobservable Inputs (Level 3) | March 2026 A Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 45,482 45,512
Unobservable Inputs (Level 3) | March 2026 B Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 45,537 45,588
Unobservable Inputs (Level 3) | September 2026 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 273,407 269,509
Unobservable Inputs (Level 3) | January 2027 Notes | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 298,106 296,826
Unobservable Inputs (Level 3) | MUFG Bank Facility | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value 61,000 107,000
Unobservable Inputs (Level 3) | SMBC Facility | Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Approximate Fair Value $ 173,000 $ 72,000