Derivatives and Hedging Activities - Effect of Derivative Financial Instruments on Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Derivative Instruments, Gain (Loss)
Gain (loss) on derivative instruments, net	$ 28,262	$ 96,624	$ 121,423	$ 51,729
Interest Rate Swaps
Derivative Instruments, Gain (Loss)
Gain (loss) on derivative instruments, net		3,200		7,700
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss)
Realized gain (loss) on derivative instruments, net	(22,344)	26,946	26,338	(64,954)
Contractual net interest income (expense)	43,271	63,437	88,558	117,901
Unrealized gain (loss), net	7,335	6,241	6,527	(1,218)
Gain (loss) on derivative instruments, net	28,262	96,624	121,423	51,729
Not Designated as Hedging Instrument | Interest Rate Swaps
Derivative Instruments, Gain (Loss)
Realized gain (loss) on derivative instruments, net	(22,871)	27,893	25,811	(63,056)
Contractual net interest income (expense)	43,271	63,437	88,558	117,901
Unrealized gain (loss), net	8,860	5,312	8,052	(2,656)
Gain (loss) on derivative instruments, net	29,260	96,642	122,421	52,189
Not Designated as Hedging Instrument | TBAs
Derivative Instruments, Gain (Loss)
Realized gain (loss) on derivative instruments, net	527	(929)	527	(1,880)
Contractual net interest income (expense)	0	0	0	0
Unrealized gain (loss), net	(1,525)	929	(1,525)	1,438
Gain (loss) on derivative instruments, net	$ (998)	0	$ (998)	(442)
Not Designated as Hedging Instrument | Currency Forward Contracts
Derivative Instruments, Gain (Loss)
Realized gain (loss) on derivative instruments, net		(18)		(18)
Contractual net interest income (expense)		0		0
Unrealized gain (loss), net		0		0
Gain (loss) on derivative instruments, net		$ (18)		$ (18)