Fair Value Measurements - Effect of Fair Value Measured Assets and Liabilities on Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	$ 919	$ 4,422
Unrealized gain (loss) on marketable securities	0	(1,477)
Derivative expense related to credit default swaps		268
Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	919	4,422
Unrealized gain (loss) on marketable securities	0	(1,477)
Realized gain (loss) on marketable securities	0	2,104
Net	919	4,824
Fair Value Measurements Recurring | Interest rate derivatives - floors
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	(71)	602
Realized gain (loss) on interest rate floors	0	(225)
Fair Value Measurements Recurring | Interest rate derivatives - caps
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	(289)	(52)
Fair Value Measurements Recurring | Credit default swaps
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	0	3,872
Fair Value Measurements Recurring | Embedded debt derivative
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	1,279	0
Fair Value Measurements Recurring | Derivative liabilities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities	919	4,824
Fair Value Measurements Recurring | Derivative liabilities | Credit default swaps
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities	0	1,442
Fair Value Measurements Recurring | Derivative liabilities | Embedded debt derivative
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities	1,279	0
Fair Value Measurements Recurring | Derivative assets
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	(360)	2,755
Fair Value Measurements Recurring | Derivative assets | Interest rate derivatives - floors
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	(71)	377
Fair Value Measurements Recurring | Derivative assets | Interest rate derivatives - caps
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	(289)	(52)
Fair Value Measurements Recurring | Derivative assets | Credit default swaps
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	0	2,430
Fair Value Measurements Recurring | Non-derivative assets
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	(360)	3,382
Fair Value Measurements Recurring | Non-derivative assets | Equity
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	$ 0	$ 627