Investment Securities - Schedule of Available-for-sale Investment Securities Portfolios (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	$ 985,052,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(8,577,000)
Continuous unrealized losses existing for greater than 12 months, fair value	2,417,897,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(441,599,000)
Total, fair value	3,402,949,000
Total, unrealized losses	(450,176,000)
Available-for-sale securities, at fair value	5,274,124,000	$ 4,141,482,000	$ 3,912,232,000
U.S. Treasury
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	0
Total, unrealized losses	0
Available-for-sale securities, at fair value	8,036,000	37,907,000	98,323,000
U.S. government agencies
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	46,511,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(3,489,000)
Total, fair value	46,511,000
Total, unrealized losses	(3,489,000)
Available-for-sale securities, at fair value	46,511,000	44,945,000	47,654,000
Municipal
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	27,180,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(276,000)
Continuous unrealized losses existing for greater than 12 months, fair value	45,372,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(1,876,000)
Total, fair value	72,552,000
Total, unrealized losses	(2,152,000)
Available-for-sale securities, at fair value	194,244,000	184,593,000	200,212,000
Financial issuers
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	79,372,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(2,628,000)
Total, fair value	79,372,000
Total, unrealized losses	(2,628,000)
Available-for-sale securities, at fair value	79,372,000	80,169,000	79,117,000
Other
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	1,000,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	1,000,000
Total, unrealized losses	0
Available-for-sale securities, at fair value	1,000,000	993,000	1,000,000
Residential mortgage-backed securities
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	746,985,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(3,625,000)
Continuous unrealized losses existing for greater than 12 months, fair value	2,174,994,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(416,350,000)
Total, fair value	2,921,979,000
Total, unrealized losses	(419,975,000)
Available-for-sale securities, at fair value	4,359,462,000	3,553,638,000	3,307,681,000
Commercial (multi-family) mortgage-backed securities
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	179,691,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(4,574,000)
Continuous unrealized losses existing for greater than 12 months, fair value	7,594,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(562,000)
Total, fair value	187,285,000
Total, unrealized losses	(5,136,000)
Available-for-sale securities, at fair value	228,338,000	18,332,000	19,141,000
Collateralized mortgage obligations
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	31,196,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(102,000)
Continuous unrealized losses existing for greater than 12 months, fair value	63,054,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(16,694,000)
Total, fair value	94,250,000
Total, unrealized losses	(16,796,000)
Available-for-sale securities, at fair value	357,161,000	220,905,000	159,104,000
Mortgage-backed securities, subprime
Available-for-sale securities
Available-for-sale securities, at fair value	$ 0	$ 0	$ 0