Debt - Schedule of Available and Outstanding Debt (Details) - USD ($) $ in Thousands |
Sep. 30, 2022 |
Dec. 31, 2021 |
Oct. 23, 2017 |
Jan. 25, 2017 |
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|---|---|---|---|---|---|---|---|---|---|---|
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | $ 2,185,000 | $ 1,745,000 | $ 150,000 | |||||||
| Principal | 1,542,000 | 1,250,425 | ||||||||
| Carrying Value | [1] | 1,521,220 | 1,236,303 | |||||||
| SBA Debentures | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 175,000 | 175,000 | ||||||||
| Principal | 175,000 | 150,500 | ||||||||
| Carrying Value | [1] | 169,591 | 145,498 | |||||||
| 2022 Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 0 | 150,000 | ||||||||
| Principal | 0 | 150,000 | ||||||||
| Carrying Value | [1] | 0 | 149,563 | |||||||
| July 2024 Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 105,000 | 105,000 | ||||||||
| Principal | 105,000 | 105,000 | ||||||||
| Carrying Value | [1] | 104,459 | 104,238 | |||||||
| February 2025 Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 50,000 | 50,000 | ||||||||
| Principal | 50,000 | 50,000 | ||||||||
| Carrying Value | [1] | 49,723 | 49,637 | |||||||
| June 2025 Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 70,000 | 70,000 | ||||||||
| Principal | 70,000 | 70,000 | ||||||||
| Carrying Value | [1] | 69,555 | 69,433 | |||||||
| June 2025 3-Year Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 50,000 | 0 | ||||||||
| Principal | 50,000 | 0 | ||||||||
| Carrying Value | [1] | 49,577 | 0 | |||||||
| March 2026 A Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 50,000 | 50,000 | ||||||||
| Principal | 50,000 | 50,000 | ||||||||
| Carrying Value | [1] | 49,676 | 49,605 | |||||||
| March 2026 B Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 50,000 | 50,000 | ||||||||
| Principal | 50,000 | 50,000 | ||||||||
| Carrying Value | [1] | 49,647 | 49,570 | |||||||
| September 2026 Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 325,000 | 325,000 | ||||||||
| Principal | 325,000 | 325,000 | ||||||||
| Carrying Value | [1] | 321,112 | 320,376 | |||||||
| January 2027 Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 350,000 | 0 | ||||||||
| Principal | 350,000 | 0 | ||||||||
| Carrying Value | [1] | 344,271 | 0 | |||||||
| 2031 Asset-Backed Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 150,000 | 0 | ||||||||
| Principal | 150,000 | 0 | ||||||||
| Carrying Value | [1] | 147,810 | 0 | |||||||
| 2033 Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 40,000 | 40,000 | ||||||||
| Principal | 40,000 | 40,000 | ||||||||
| Carrying Value | [1] | 38,799 | 38,718 | |||||||
| 2022 Convertible Notes | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | 0 | 230,000 | $ 230,000 | |||||||
| Principal | 0 | 230,000 | ||||||||
| Carrying Value | [1] | 0 | 229,740 | |||||||
| MUFG Bank Facility | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | [2],[3] | 545,000 | 400,000 | |||||||
| Principal | [2],[3] | 102,000 | 0 | |||||||
| Carrying Value | [1],[2],[3] | 102,000 | 0 | |||||||
| SMBC Facility | ||||||||||
| Debt Instrument [Line Items] | ||||||||||
| Outstanding balance | [2] | 225,000 | 100,000 | |||||||
| Principal | [2] | 25,000 | 29,925 | |||||||
| Carrying Value | [1],[2] | $ 25,000 | $ 29,925 | |||||||
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