Fair Value Measurements - Changes in the Fair Value of Securities Classified as Level 3 (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Fair Value, Assets Measured on Recurring Basis [Roll Forward]
Transfers into Level 3	$ 0	$ 0
Transfers out of Level 3	$ 0	$ 0
Gains (losses) included in net income
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration]	Net unrealized gains (losses) on financial instruments at fair value	Net unrealized gains (losses) on financial instruments at fair value
Securitized debt at fair value, collateralized by loans held for investment | Variable Interest Entities, Primary Beneficiary | Level 3
Gains (losses) included in net income
Gains (losses) included in other comprehensive income	$ 0	$ 0
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Beginning balance Level 3	6,984,495,000	7,601,881,000
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Issuance of debt	780,166,000	340,096,000
Principal payments	(284,776,000)	(1,170,579,000)
Sales and Settlements	(316,078,000)	0
Net (accretion) amortization	3,913,000	17,039,000
Realized (gains) losses on sales and settlements	2,122,000	0
Net unrealized (gains) losses included in income	28,246,000	196,058,000
Gains (losses) included in other comprehensive income	0	0
Securitized Debt, Ending balance, Level 3	7,198,089,000	6,984,495,000
Non-Agency RMBS | Level 3
Fair Value, Assets Measured on Recurring Basis [Roll Forward]
Beginning balance Level 3	1,064,169,000	1,043,806,000
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases of assets	454,000	97,646,000
Principal payments	(16,604,000)	(74,091,000)
Sales and settlements	0	0
Net (accretion) amortization	5,543,000	34,267,000
Gains (losses) included in net income
(Increase) decrease in provision for credit losses	(3,387,000)	(9,869,000)
Realized gains (losses) on sales and settlements	0	0
Net unrealized (gains) losses included in income	11,344,000	(1,391,000)
Gains (losses) included in other comprehensive income	(1,679,000)	(26,199,000)
Ending balance Level 3	1,059,840,000	1,064,169,000
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Gains (losses) included in other comprehensive income	1,679,000	26,199,000
Loans held for investment | Variable Interest Entities, Primary Beneficiary | Level 3
Fair Value, Assets Measured on Recurring Basis [Roll Forward]
Beginning balance Level 3	10,858,845,000	11,125,052,000
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases of assets	(21,428,000)	759,900,000
Principal payments	(288,720,000)	(1,184,167,000)
Sales and settlements	(1,782,000)	(3,441,000)
Net (accretion) amortization	(1,700,000)	(39,490,000)
Gains (losses) included in net income
(Increase) decrease in provision for credit losses	0	0
Realized gains (losses) on sales and settlements	0	0
Net unrealized (gains) losses included in income	151,927,000	200,991,000
Gains (losses) included in other comprehensive income	0	0
Ending balance Level 3	10,697,143,000	10,858,845,000
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Gains (losses) included in other comprehensive income	$ 0	$ 0