Credit Risk and Interest Rate Risk (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Secured financing agreements
Gross Amounts of Recognized  Assets (Liabilities)	$ (2,994,191)	$ (2,824,371)
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	0
Net Amounts Offset in the Consolidated Statements of Financial Position	(2,994,191)	(2,824,371)
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	4,222,227	4,086,097
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	10,604	17,340
Net Amount	1,238,640	1,279,066
Derivative Asset
Net Amounts Offset in the Consolidated Statements of Financial Position	0	117
Derivative Liability
Net Amounts Offset in the Consolidated Statements of Financial Position	(240)	0
Total Repurchase Agreements and Swaptions
Gross Amounts of Recognized  Assets (Liabilities)	(2,985,913)	(2,817,109)
Gross Amounts Offset in the Consolidated Statements of Financial Position	(8,518)	(7,145)
Net Amounts Offset in the Consolidated Statements of Financial Position	(2,994,431)	(2,824,254)
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	4,222,227	4,086,097
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	(5,521)	4,554
Net Amount	1,222,275	1,266,396
Interest Rate Swaps
Derivative Asset
Gross Amounts of Recognized  Assets (Liabilities)	3,276	3,754
Gross Amounts Offset in the Consolidated Statements of Financial Position	(3,276)	(3,754)
Net Amounts Offset in the Consolidated Statements of Financial Position	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	0	0
Net Amount	0	0
Derivative Liability
Gross Amounts of Recognized  Assets (Liabilities)	0	0
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	0
Net Amounts Offset in the Consolidated Statements of Financial Position	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	(17,255)	(13,486)
Net Amount	(17,255)	(13,486)
Swap futures
Derivative Asset
Gross Amounts of Recognized  Assets (Liabilities)	0
Gross Amounts Offset in the Consolidated Statements of Financial Position	0
Net Amounts Offset in the Consolidated Statements of Financial Position	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	1,568
Net Amount	1,568
Derivative Liability
Gross Amounts of Recognized  Assets (Liabilities)	(240)
Gross Amounts Offset in the Consolidated Statements of Financial Position	0
Net Amounts Offset in the Consolidated Statements of Financial Position	(240)
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	0
Net Amount	(240)
U.S. Treasury futures
Derivative Asset
Gross Amounts of Recognized  Assets (Liabilities)		117
Gross Amounts Offset in the Consolidated Statements of Financial Position		0
Net Amounts Offset in the Consolidated Statements of Financial Position	0	117
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments		0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged		0
Net Amount		117
Derivative Liability
Gross Amounts of Recognized  Assets (Liabilities)		0
Gross Amounts Offset in the Consolidated Statements of Financial Position		0
Net Amounts Offset in the Consolidated Statements of Financial Position	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments		0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged		1,098
Net Amount		1,098
Swaptions
Derivative Asset
Gross Amounts of Recognized  Assets (Liabilities)	0	0
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	0
Net Amounts Offset in the Consolidated Statements of Financial Position	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	0	0
Net Amount	0	0
Derivative Liability
Gross Amounts of Recognized  Assets (Liabilities)	0	3,391
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	(3,391)
Net Amounts Offset in the Consolidated Statements of Financial Position	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	0	(399)
Net Amount	0	$ (399)
Interest Rate Cap
Derivative Asset
Gross Amounts of Recognized  Assets (Liabilities)	5,242
Gross Amounts Offset in the Consolidated Statements of Financial Position	(5,242)
Net Amounts Offset in the Consolidated Statements of Financial Position	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	(438)
Net Amount	(438)
Derivative Liability
Gross Amounts of Recognized  Assets (Liabilities)	0
Gross Amounts Offset in the Consolidated Statements of Financial Position	0
Net Amounts Offset in the Consolidated Statements of Financial Position	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Financial Instruments	0
Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position, Cash Collateral (Received) Pledged	0
Net Amount	$ 0