Investment Securities - Schedule of Investment Securities (Details) - USD ($) |
Sep. 30, 2026 |
Dec. 31, 2025 |
Sep. 30, 2025 |
|---|---|---|---|
| Available-for-sale securities | |||
| Amortized Cost | $ 8,507,107,000 | $ 6,635,481,000 | $ 5,702,349,000 |
| Gross Unrealized Gains | 70,000 | 30,480,000 | 21,951,000 |
| Gross Unrealized Losses | (937,679,000) | (429,698,000) | (450,176,000) |
| Fair Value | 7,569,498,000 | 6,236,263,000 | 5,274,124,000 |
| Held-to-maturity securities | |||
| Amortized Cost | 3,120,716,000 | 3,344,165,000 | 3,438,801,000 |
| Gross Unrealized Gains | 60,000 | 8,864,000 | 6,950,000 |
| Gross Unrealized Losses | (727,256,000) | (567,882,000) | (584,781,000) |
| Fair Value | 2,393,520,000 | 2,785,147,000 | 2,860,970,000 |
| Less: Allowance for credit losses | (213,000) | (260,000) | (395,000) |
| Held-to-maturity securities, net of allowance for credit losses | 3,120,503,000 | 3,343,905,000 | 3,438,406,000 |
| Equity securities with readily determinable fair value | |||
| Amortized Cost | 62,242,000 | 61,211,000 | 60,843,000 |
| Gross Unrealized Gains | 7,960,000 | 6,318,000 | 6,520,000 |
| Gross Unrealized Losses | (5,391,000) | (3,759,000) | (3,918,000) |
| Fair Value | 64,811,000 | 63,770,000 | 63,445,000 |
| U.S. Treasury | |||
| Available-for-sale securities | |||
| Amortized Cost | 3,000,000 | 6,999,000 | 7,997,000 |
| Gross Unrealized Gains | 0 | 36,000 | 39,000 |
| Gross Unrealized Losses | 0 | 0 | 0 |
| Fair Value | 3,000,000 | 7,035,000 | 8,036,000 |
| U.S. government agencies | |||
| Available-for-sale securities | |||
| Amortized Cost | 50,000,000 | 50,000,000 | 50,000,000 |
| Gross Unrealized Gains | 0 | 0 | 0 |
| Gross Unrealized Losses | (6,169,000) | (2,529,000) | (3,489,000) |
| Fair Value | 43,831,000 | 47,471,000 | 46,511,000 |
| Held-to-maturity securities | |||
| Amortized Cost | 313,542,000 | 313,541,000 | 313,540,000 |
| Gross Unrealized Gains | 0 | 0 | 0 |
| Gross Unrealized Losses | (79,946,000) | (57,269,000) | (59,178,000) |
| Fair Value | 233,596,000 | 256,272,000 | 254,362,000 |
| Municipal | |||
| Available-for-sale securities | |||
| Amortized Cost | 171,215,000 | 162,373,000 | 194,723,000 |
| Gross Unrealized Gains | 30,000 | 1,643,000 | 1,673,000 |
| Gross Unrealized Losses | (6,921,000) | (1,850,000) | (2,152,000) |
| Fair Value | 164,324,000 | 162,166,000 | 194,244,000 |
| Held-to-maturity securities | |||
| Amortized Cost | 133,408,000 | 144,192,000 | 155,770,000 |
| Gross Unrealized Gains | 57,000 | 451,000 | 458,000 |
| Gross Unrealized Losses | (6,709,000) | (2,012,000) | (2,283,000) |
| Fair Value | 126,756,000 | 142,631,000 | 153,945,000 |
| Corporate notes | |||
| Held-to-maturity securities | |||
| Amortized Cost | 7,975,000 | 35,097,000 | 50,511,000 |
| Gross Unrealized Gains | 0 | 2,000 | 26,000 |
| Gross Unrealized Losses | (293,000) | (396,000) | (653,000) |
| Fair Value | 7,682,000 | 34,703,000 | 49,884,000 |
| Financial issuers | |||
| Available-for-sale securities | |||
| Amortized Cost | 75,000,000 | 79,000,000 | 82,000,000 |
| Gross Unrealized Gains | 0 | 0 | 0 |
| Gross Unrealized Losses | (1,944,000) | (2,704,000) | (2,628,000) |
| Fair Value | 73,056,000 | 76,296,000 | 79,372,000 |
| Other | |||
| Available-for-sale securities | |||
| Amortized Cost | 1,000,000 | 1,000,000 | 1,000,000 |
| Gross Unrealized Gains | 0 | 0 | 0 |
| Gross Unrealized Losses | (38,000) | (1,000) | 0 |
| Fair Value | 962,000 | 999,000 | 1,000,000 |
| Residential mortgage-backed securities | |||
| Available-for-sale securities | |||
| Amortized Cost | 6,928,051,000 | 5,533,710,000 | 4,761,918,000 |
| Gross Unrealized Gains | 15,000 | 25,926,000 | 17,519,000 |
| Gross Unrealized Losses | (850,890,000) | (402,953,000) | (419,975,000) |
| Fair Value | 6,077,176,000 | 5,156,683,000 | 4,359,462,000 |
| Held-to-maturity securities | |||
| Amortized Cost | 2,475,956,000 | 2,667,371,000 | 2,724,442,000 |
| Gross Unrealized Gains | 0 | 7,503,000 | 5,421,000 |
| Gross Unrealized Losses | (611,175,000) | (491,124,000) | (505,165,000) |
| Fair Value | 1,864,781,000 | 2,183,750,000 | 2,224,698,000 |
| Commercial (multi-family) mortgage-backed securities | |||
| Available-for-sale securities | |||
| Amortized Cost | 388,399,000 | 280,969,000 | 233,127,000 |
| Gross Unrealized Gains | 0 | 570,000 | 347,000 |
| Gross Unrealized Losses | (28,242,000) | (4,986,000) | (5,136,000) |
| Fair Value | 360,157,000 | 276,553,000 | 228,338,000 |
| Held-to-maturity securities | |||
| Amortized Cost | 35,838,000 | 6,293,000 | 6,315,000 |
| Gross Unrealized Gains | 0 | 72,000 | 65,000 |
| Gross Unrealized Losses | (5,135,000) | (92,000) | (102,000) |
| Fair Value | 30,703,000 | 6,273,000 | 6,278,000 |
| Collateralized mortgage obligations | |||
| Available-for-sale securities | |||
| Amortized Cost | 890,442,000 | 521,430,000 | 371,584,000 |
| Gross Unrealized Gains | 25,000 | 2,305,000 | 2,373,000 |
| Gross Unrealized Losses | (43,475,000) | (14,675,000) | (16,796,000) |
| Fair Value | 846,992,000 | 509,060,000 | 357,161,000 |
| Held-to-maturity securities | |||
| Amortized Cost | 153,997,000 | 177,671,000 | 188,223,000 |
| Gross Unrealized Gains | 3,000 | 836,000 | 980,000 |
| Gross Unrealized Losses | (23,998,000) | (16,989,000) | (17,400,000) |
| Fair Value | 130,002,000 | 161,518,000 | 171,803,000 |
| Mortgage-backed securities, subprime | |||
| Available-for-sale securities | |||
| Fair Value | $ 0 | $ 0 | $ 0 |