Held-to-Maturity Securities - Schedule of Major Security Types (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Issued, guaranteed or insured:
Amortized Cost	$ 12,276,485	$ 10,490,243
Allowance for Credit Loss (ACL)	(86)	(76)
OTTI Recognized in AOCI	0	0
Carrying Value	12,276,399	10,490,167
Gross Unrecognized Holding Gains	2,578	17,720
Gross Unrecognized Holding Losses	(276,455)	(123,507)
Fair Value	12,002,522	10,384,380
Pools of Mortgages
Issued, guaranteed or insured:
Amortized Cost	14,604	17,557
Allowance for Credit Loss (ACL)	0	0
OTTI Recognized in AOCI	0	0
Carrying Value	14,604	17,557
Gross Unrecognized Holding Gains	0	334
Gross Unrecognized Holding Losses	(299)	0
Fair Value	14,305	17,891
Collateralized Mortgage Obligations/Real Estate Mortgage Investment Conduits
Issued, guaranteed or insured:
Amortized Cost	4,555,178	2,914,512
Allowance for Credit Loss (ACL)	0	0
OTTI Recognized in AOCI	0	0
Carrying Value	4,555,178	2,914,512
Gross Unrecognized Holding Gains	291	9,966
Gross Unrecognized Holding Losses	(73,847)	(6,924)
Fair Value	4,481,622	2,917,554
CMBS
Issued, guaranteed or insured:
Amortized Cost	7,534,558	7,406,494
Allowance for Credit Loss (ACL)	0	0
OTTI Recognized in AOCI	0	0
Carrying Value	7,534,558	7,406,494
Gross Unrecognized Holding Gains	2,287	7,420
Gross Unrecognized Holding Losses	(197,639)	(111,764)
Fair Value	7,339,206	7,302,150
Total MBS
Issued, guaranteed or insured:
Amortized Cost	12,104,340	10,338,563
Allowance for Credit Loss (ACL)	0	0
OTTI Recognized in AOCI	0	0
Carrying Value	12,104,340	10,338,563
Gross Unrecognized Holding Gains	2,578	17,720
Gross Unrecognized Holding Losses	(271,785)	(118,688)
Fair Value	11,835,133	10,237,595
State and local housing finance agency obligations
Issued, guaranteed or insured:
Amortized Cost	172,145	151,680
Allowance for Credit Loss (ACL)	(86)	(76)
OTTI Recognized in AOCI	0	0
Carrying Value	172,059	151,604
Gross Unrecognized Holding Gains	0	0
Gross Unrecognized Holding Losses	(4,670)	(4,819)
Fair Value	$ 167,389	$ 146,785

Other Comprehensive Income (Loss), Other Than Temporary Impairment, Held To Maturity Debt Securities, Net Of Tax

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