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Investment Securities - Schedule of Gross Unrealized Losses on Investment Securities AFS (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
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Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | $ 28,151 | $ 2,979,465
Less than 12 months, gross unrealized losses | (176) | (37,202)
12 months or longer, fair value | 3,085,405 | 2,956,231
12 months or longer, gross unrealized losses | (371,368) | (500,723)
Total, fair value | 3,113,556 | 5,935,696
Total, gross unrealized losses | (371,544) | (537,925)
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value |  | 716,367
Less than 12 months, gross unrealized losses |  | (4,824)
12 months or longer, fair value |  | 0
12 months or longer, gross unrealized losses |  | 0
Total, fair value |  | 716,367
Total, gross unrealized losses |  | (4,824)
U.S. Government agency securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 0
Less than 12 months, gross unrealized losses | 0 | 0
12 months or longer, fair value | 29,857 | 29,163
12 months or longer, gross unrealized losses | (138) | (830)
Total, fair value | 29,857 | 29,163
Total, gross unrealized losses | (138) | (830)
Mortgage-backed securities issued by U.S. Government agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 716,268
Less than 12 months, gross unrealized losses | 0 | (8,431)
12 months or longer, fair value | 611,363 | 577,468
12 months or longer, gross unrealized losses | (89,072) | (112,958)
Total, fair value | 611,363 | 1,293,736
Total, gross unrealized losses | (89,072) | (121,389)
Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 456,887
Less than 12 months, gross unrealized losses | 0 | (12,503)
12 months or longer, fair value | 1,600,160 | 1,542,618
12 months or longer, gross unrealized losses | (176,679) | (248,412)
Total, fair value | 1,600,160 | 1,999,505
Total, gross unrealized losses | (176,679) | (260,915)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 28,151 | 29,040
Less than 12 months, gross unrealized losses | (176) | (820)
12 months or longer, fair value | 491,047 | 521,161
12 months or longer, gross unrealized losses | (84,152) | (106,432)
Total, fair value | 519,198 | 550,201
Total, gross unrealized losses | (84,328) | (107,252)
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 1,060,903
Less than 12 months, gross unrealized losses | 0 | (10,624)
12 months or longer, fair value | 352,978 | 276,850
12 months or longer, gross unrealized losses | (21,327) | (31,952)
Total, fair value | 352,978 | 1,337,753
Total, gross unrealized losses | $ (21,327) | (42,576)
Corporate debt securities and other debt securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value |  | 0
Less than 12 months, gross unrealized losses |  | 0
12 months or longer, fair value |  | 8,971
12 months or longer, gross unrealized losses |  | (139)
Total, fair value |  | 8,971
Total, gross unrealized losses |  | $ (139)

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