Investment Securities - Schedule of Investment Securities (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Available-for-sale securities
Amortized Cost	$ 5,702,349,000	$ 4,725,539,000	$ 4,320,843,000
Gross Unrealized Gains	21,951,000	2,071,000	11,552,000
Gross Unrealized Losses	(450,176,000)	(586,128,000)	(420,163,000)
Fair Value	5,274,124,000	4,141,482,000	3,912,232,000
Held-to-maturity securities
Amortized Cost	3,438,801,000	3,613,720,000	3,677,899,000
Gross Unrealized Gains	6,950,000	1,066,000	7,526,000
Gross Unrealized Losses	(584,781,000)	(704,236,000)	(563,605,000)
Fair Value	2,860,970,000	2,910,550,000	3,121,820,000
Less: Allowance for credit losses	(395,000)	(457,000)	(479,000)
Held-to-maturity securities, net of allowance for credit losses	3,438,406,000	3,613,263,000	3,677,420,000
Equity securities with readily determinable fair value
Amortized Cost	60,843,000	220,758,000	127,700,000
Gross Unrealized Gains	6,520,000	2,905,000	4,313,000
Gross Unrealized Losses	(3,918,000)	(8,251,000)	(6,703,000)
Fair Value	63,445,000	215,412,000	125,310,000
U.S. Treasury
Available-for-sale securities
Amortized Cost	7,997,000	37,858,000	98,151,000
Gross Unrealized Gains	39,000	49,000	172,000
Gross Unrealized Losses	0	0	0
Fair Value	8,036,000	37,907,000	98,323,000
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	(3,489,000)	(5,055,000)	(2,346,000)
Fair Value	46,511,000	44,945,000	47,654,000
Held-to-maturity securities
Amortized Cost	313,540,000	313,539,000	314,578,000
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	(59,178,000)	(69,127,000)	(56,198,000)
Fair Value	254,362,000	244,412,000	258,380,000
Municipal
Available-for-sale securities
Amortized Cost	194,723,000	188,405,000	201,701,000
Gross Unrealized Gains	1,673,000	528,000	1,392,000
Gross Unrealized Losses	(2,152,000)	(4,340,000)	(2,881,000)
Fair Value	194,244,000	184,593,000	200,212,000
Held-to-maturity securities
Amortized Cost	155,770,000	161,016,000	165,141,000
Gross Unrealized Gains	458,000	243,000	488,000
Gross Unrealized Losses	(2,283,000)	(5,290,000)	(2,910,000)
Fair Value	153,945,000	155,969,000	162,719,000
Corporate notes
Held-to-maturity securities
Amortized Cost	50,511,000	56,851,000	57,025,000
Gross Unrealized Gains	26,000	8,000	0
Gross Unrealized Losses	(653,000)	(1,870,000)	(1,953,000)
Fair Value	49,884,000	54,989,000	55,072,000
Financial issuers
Available-for-sale securities
Amortized Cost	82,000,000	83,997,000	83,997,000
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	(2,628,000)	(3,828,000)	(4,880,000)
Fair Value	79,372,000	80,169,000	79,117,000
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	0	(7,000)	0
Fair Value	1,000,000	993,000	1,000,000
Residential mortgage-backed securities
Available-for-sale securities
Amortized Cost	4,761,918,000	4,106,641,000	3,694,382,000
Gross Unrealized Gains	17,519,000	284,000	8,143,000
Gross Unrealized Losses	(419,975,000)	(553,287,000)	(394,844,000)
Fair Value	4,359,462,000	3,553,638,000	3,307,681,000
Held-to-maturity securities
Amortized Cost	2,724,442,000	2,864,927,000	2,915,018,000
Gross Unrealized Gains	5,421,000	0	5,541,000
Gross Unrealized Losses	(505,165,000)	(605,014,000)	(485,115,000)
Fair Value	2,224,698,000	2,259,913,000	2,435,444,000
Commercial (multi-family) mortgage-backed securities
Available-for-sale securities
Amortized Cost	233,127,000	19,064,000	19,088,000
Gross Unrealized Gains	347,000	23,000	308,000
Gross Unrealized Losses	(5,136,000)	(755,000)	(255,000)
Fair Value	228,338,000	18,332,000	19,141,000
Held-to-maturity securities
Amortized Cost	6,315,000	6,364,000	6,379,000
Gross Unrealized Gains	65,000	0	40,000
Gross Unrealized Losses	(102,000)	(252,000)	(126,000)
Fair Value	6,278,000	6,112,000	6,293,000
Collateralized mortgage obligations
Available-for-sale securities
Amortized Cost	371,584,000	238,574,000	172,524,000
Gross Unrealized Gains	2,373,000	1,187,000	1,537,000
Gross Unrealized Losses	(16,796,000)	(18,856,000)	(14,957,000)
Fair Value	357,161,000	220,905,000	159,104,000
Held-to-maturity securities
Amortized Cost	188,223,000	211,023,000	219,758,000
Gross Unrealized Gains	980,000	815,000	1,457,000
Gross Unrealized Losses	(17,400,000)	(22,683,000)	(17,303,000)
Fair Value	171,803,000	189,155,000	203,912,000
Mortgage-backed securities, subprime
Available-for-sale securities
Fair Value	$ 0	$ 0	$ 0