Investment Securities - Schedule of Available-for-sale Investment Securities Portfolios (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	$ 111,475,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(1,326,000)
Continuous unrealized losses existing for greater than 12 months, fair value	2,563,051,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(418,837,000)
Total, fair value	2,674,526,000
Total, unrealized losses	(420,163,000)
Available-for-sale securities, at fair value	3,912,232,000	$ 3,502,915,000	$ 3,611,835,000
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	98,323,000	6,968,000	4,931,000
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	47,654,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(2,346,000)
Total, fair value	47,654,000
Total, unrealized losses	(2,346,000)
Available-for-sale securities, at fair value	47,654,000	45,124,000	72,430,000
Municipal
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	10,111,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(54,000)
Continuous unrealized losses existing for greater than 12 months, fair value	68,124,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(2,827,000)
Total, fair value	78,235,000
Total, unrealized losses	(2,881,000)
Available-for-sale securities, at fair value	200,212,000	140,958,000	168,523,000
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	79,117,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(4,880,000)
Total, fair value	79,117,000
Total, unrealized losses	(4,880,000)
Available-for-sale securities, at fair value	79,117,000	75,540,000	75,627,000
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	991,000	979,000
Residential mortgage-backed securities
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	98,365,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(1,252,000)
Continuous unrealized losses existing for greater than 12 months, fair value	2,292,584,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(393,592,000)
Total, fair value	2,390,949,000
Total, unrealized losses	(394,844,000)
Available-for-sale securities, at fair value	3,307,681,000	3,059,620,000	3,206,736,000
Commercial (multi-family) mortgage-backed securities
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	2,999,000
Continuous unrealized losses existing for less than 12 months, unrealized losses	(20,000)
Continuous unrealized losses existing for greater than 12 months, fair value	3,295,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(235,000)
Total, fair value	6,294,000
Total, unrealized losses	(255,000)
Available-for-sale securities, at fair value	19,141,000	12,980,000	12,377,000
Collateralized mortgage obligations
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	71,277,000
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(14,957,000)
Total, fair value	71,277,000
Total, unrealized losses	(14,957,000)
Available-for-sale securities, at fair value	159,104,000	160,734,000	70,232,000
Mortgage-backed securities, subprime
Available-for-sale securities
Available-for-sale securities, at fair value	$ 0	$ 0	$ 0