Fair Value of Assets and Liabilities - Carrying Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Assets:
Cash and cash equivalents	$ 587,861	$ 506,491	$ 483,048
Carrying Value
Assets:
Cash and cash equivalents	587,861	506,491
Restricted cash and investments	48,933	41,831
Liabilities:
Borrowings under senior credit facility	1,493,000	1,546,895
Non-recourse debt	290,150	310,108
Fair Value
Assets:
Cash and cash equivalents	587,861	506,491
Restricted cash and investments	48,933	41,831
Liabilities:
Borrowings under senior credit facility	1,388,720	1,448,280
Non-recourse debt	290,150	310,108
Level 1 | Fair Value
Assets:
Cash and cash equivalents	587,861	506,491
Restricted cash and investments	48,933	41,831
Level 2 | Fair Value
Liabilities:
Borrowings under senior credit facility	1,388,720	1,448,280
Non-recourse debt	290,150	310,108
5.125% Senior Notes due 2023 | Carrying Value
Liabilities:
Senior notes, fair value	259,275	259,275
5.125% Senior Notes due 2023 | Fair Value
Liabilities:
Senior notes, fair value	246,595	248,479
5.125% Senior Notes due 2023 | Level 2 | Fair Value
Liabilities:
Senior notes, fair value	246,595	248,479
5.875% Senior Notes due 2024 | Carrying Value
Liabilities:
Senior notes, fair value	225,293	225,293
5.875% Senior Notes due 2024 | Fair Value
Liabilities:
Senior notes, fair value	202,766	199,522
5.875% Senior Notes due 2024 | Level 2 | Fair Value
Liabilities:
Senior notes, fair value	202,766	199,522
6.00% Senior Notes due 2026 | Carrying Value
Liabilities:
Senior notes, fair value	350,000	350,000
6.00% Senior Notes due 2026 | Fair Value
Liabilities:
Senior notes, fair value	285,724	283,691
6.00% Senior Notes due 2026 | Level 2 | Fair Value
Liabilities:
Senior notes, fair value	285,724	283,691
6.50% Exchangeable Senior Notes due 2026 | Carrying Value
Liabilities:
Senior notes, fair value	230,000	230,000
6.50% Exchangeable Senior Notes due 2026 | Fair Value
Liabilities:
Senior notes, fair value	222,609	248,211
6.50% Exchangeable Senior Notes due 2026 | Level 2 | Fair Value
Liabilities:
Senior notes, fair value	$ 222,609	$ 248,211