Borrowings - Schedule of Borrowings (Details) - USD ($) |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|---|---|---|---|---|
| Debt Instrument [Line Items] | |||||||
| Principal | $ 519,250,000 | $ 559,250,000 | $ 81,000,000 | $ 99,000,000 | $ 61,000,000 | $ 59,500,000 | $ 0 |
| Carrying Value | 510,078,000 | 548,957,000 | |||||
| Credit Facility | |||||||
| Debt Instrument [Line Items] | |||||||
| Principal | 272,000,000 | 337,000,000 | $ 61,000,000 | $ 99,000,000 | $ 61,000,000 | ||
| Borrowings | |||||||
| Debt Instrument [Line Items] | |||||||
| Total Commitment | 797,250,000 | 647,250,000 | |||||
| Principal | 519,250,000 | 559,250,000 | |||||
| Deferred Debt Cost | (9,172,000) | (10,293,000) | |||||
| Carrying Value | 510,078,000 | 548,957,000 | |||||
| Borrowings | Credit Facility | |||||||
| Debt Instrument [Line Items] | |||||||
| Total Commitment | 550,000,000 | 425,000,000 | |||||
| Principal | 272,000,000 | 337,000,000 | |||||
| Deferred Debt Cost | (4,434,000) | (4,640,000) | |||||
| Carrying Value | 267,566,000 | 332,360,000 | |||||
| Borrowings | April 2026 Notes | |||||||
| Debt Instrument [Line Items] | |||||||
| Total Commitment | 25,000,000 | ||||||
| Principal | 25,000,000 | ||||||
| Deferred Debt Cost | (277,000) | ||||||
| Carrying Value | 24,723,000 | ||||||
| Borrowings | December 2026 Notes | |||||||
| Debt Instrument [Line Items] | |||||||
| Total Commitment | 70,000,000 | 70,000,000 | |||||
| Principal | 70,000,000 | 70,000,000 | |||||
| Deferred Debt Cost | (573,000) | (818,000) | |||||
| Carrying Value | 69,427,000 | 69,182,000 | |||||
| Borrowings | July 2027 Notes | |||||||
| Debt Instrument [Line Items] | |||||||
| Total Commitment | 80,500,000 | 80,500,000 | |||||
| Principal | 80,500,000 | 80,500,000 | |||||
| Deferred Debt Cost | (1,924,000) | (2,380,000) | |||||
| Carrying Value | 78,576,000 | 78,120,000 | |||||
| Borrowings | August 2027 Notes | |||||||
| Debt Instrument [Line Items] | |||||||
| Total Commitment | 20,000,000 | 20,000,000 | |||||
| Principal | 20,000,000 | 20,000,000 | |||||
| Deferred Debt Cost | (511,000) | (653,000) | |||||
| Carrying Value | 19,489,000 | 19,347,000 | |||||
| Borrowings | December 2027 Notes | |||||||
| Debt Instrument [Line Items] | |||||||
| Total Commitment | 51,750,000 | 51,750,000 | |||||
| Principal | 51,750,000 | 51,750,000 | |||||
| Deferred Debt Cost | (1,453,000) | (1,802,000) | |||||
| Carrying Value | $ 50,297,000 | $ 49,948,000 |