v3.26.3
Available-for-Sale Securities - Schedule of Available-for-sale Securities with Estimated Fair Values Below their Amortized Cost Basis (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Debt Securities, Available-for-Sale, Unrealized Loss Position [Abstract]    
Less than 12 months, Estimated Fair Value $ 6,875,302 $ 1,707,834
12 months or more, Estimated Fair Value 4,524,932 6,302,864
Total, Estimated Fair Value 11,400,234 8,010,698
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Unrealized Losses (346,672) (3,617)
12 months or more, Unrealized Losses (615,012) (450,841)
Total, Unrealized Losses (961,684) (454,458)
Mortgage-backed securities    
Debt Securities, Available-for-Sale, Unrealized Loss Position [Abstract]    
Less than 12 months, Estimated Fair Value 5,959,523 493,323
12 months or more, Estimated Fair Value 4,524,932 6,302,864
Total, Estimated Fair Value 10,484,455 6,796,187
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Unrealized Losses (331,780) (2,353)
12 months or more, Unrealized Losses (615,012) (450,841)
Total, Unrealized Losses (946,792) (453,194)
MBS-Other U.S. Obligations    
Debt Securities, Available-for-Sale, Unrealized Loss Position [Abstract]    
Less than 12 months, Estimated Fair Value 667 0
12 months or more, Estimated Fair Value 2,237 2,481
Total, Estimated Fair Value 2,904 2,481
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Unrealized Losses 0 0
12 months or more, Unrealized Losses (25) (19)
Total, Unrealized Losses (25) (19)
MBS-GSE    
Debt Securities, Available-for-Sale, Unrealized Loss Position [Abstract]    
Less than 12 months, Estimated Fair Value 5,958,856 493,323
12 months or more, Estimated Fair Value 4,522,695 6,300,383
Total, Estimated Fair Value 10,481,551 6,793,706
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Unrealized Losses (331,780) (2,353)
12 months or more, Unrealized Losses (614,987) (450,822)
Total, Unrealized Losses (946,767) (453,175)
Housing and U.S. obligations    
Debt Securities, Available-for-Sale, Unrealized Loss Position [Abstract]    
Less than 12 months, Estimated Fair Value 915,779 1,214,511
12 months or more, Estimated Fair Value 0 0
Total, Estimated Fair Value 915,779 1,214,511
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Unrealized Losses (14,892) (1,264)
12 months or more, Unrealized Losses 0 0
Total, Unrealized Losses $ (14,892) $ (1,264)