Investment Securities - Amortized Cost and Fair Value of Securities (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Available for sale debt securities
Amortized Cost	$ 4,267,809,000	$ 4,267,809,000	$ 8,560,733,000
Unrealized Gains	987,000	987,000	24,595,000
Unrealized Losses	(301,050,000)	(301,050,000)	(157,296,000)
Total available-for-sale securities, Fair value,	3,967,746,000	3,967,746,000	8,428,032,000
Held to maturity securities
Amortized Cost	4,093,215,000	4,093,215,000
Unrealized Losses	(182,435,000)	(182,435,000)
Total held to maturity, Fair value,	3,910,780,000	3,910,780,000	0
Available-for-sale investment securities
Accrued interest receivable related to available-for-sale investment securities	8,700,000	8,700,000	14,100,000
Accrued interest receivable related to held to maturity investment securities	7,000,000.0	7,000,000.0	0
Reclassification of available for sale securities to held to maturity	4,100,000,000	4,100,000,000
Other comprehensive income (loss), transfer of securities from available for sale to held to maturity	338,800,000	338,800,000
Gain (loss) recognized on reclassification, transfer of securities from available for sale to held to maturity	0	$ 0
Securities held-to-maturity, weighted average life		8 years
Collateralized Loan Obligations
Available for sale debt securities
Amortized Cost	249,905,000	$ 249,905,000	105,245,000
Unrealized Gains	45,000	45,000	2,000
Unrealized Losses	(3,247,000)	(3,247,000)
Total available-for-sale securities, Fair value,	246,703,000	246,703,000	105,247,000
U.S. Treasury and government agency debt securities
Available for sale debt securities
Amortized Cost	168,129,000	168,129,000	196,662,000
Unrealized Gains			125,000
Unrealized Losses	(8,964,000)	(8,964,000)	(4,224,000)
Total available-for-sale securities, Fair value,	159,165,000	159,165,000	192,563,000
Held to maturity securities
Amortized Cost	55,148,000	55,148,000
Unrealized Losses	(2,405,000)	(2,405,000)
Total held to maturity, Fair value,	52,743,000	52,743,000
Government-sponsored enterprises debt securities
Available for sale debt securities
Amortized Cost	20,000,000	20,000,000
Unrealized Losses	(37,000)	(37,000)
Total available-for-sale securities, Fair value,	19,963,000	19,963,000
Residential - Government agency
Available for sale debt securities
Amortized Cost	72,027,000	72,027,000	135,764,000
Unrealized Gains			1,791,000
Unrealized Losses	(4,069,000)	(4,069,000)	(291,000)
Total available-for-sale securities, Fair value,	67,958,000	67,958,000	137,264,000
Held to maturity securities
Amortized Cost	47,309,000	47,309,000
Unrealized Losses	(3,031,000)	(3,031,000)
Total held to maturity, Fair value,	44,278,000	44,278,000
Residential - Government-sponsored enterprises
Available for sale debt securities
Amortized Cost	1,444,461,000	1,444,461,000	1,496,605,000
Unrealized Gains	24,000	24,000	6,914,000
Unrealized Losses	(111,470,000)	(111,470,000)	(12,419,000)
Total available-for-sale securities, Fair value,	1,333,015,000	1,333,015,000	1,491,100,000
Held to maturity securities
Amortized Cost	93,458,000	93,458,000
Unrealized Losses	(6,117,000)	(6,117,000)
Total held to maturity, Fair value,	87,341,000	87,341,000
Commercial - Government agency
Available for sale debt securities
Amortized Cost	297,271,000	297,271,000	392,443,000
Unrealized Gains			1,741,000
Unrealized Losses	(29,614,000)	(29,614,000)	(6,521,000)
Total available-for-sale securities, Fair value,	267,657,000	267,657,000	387,663,000
Held to maturity securities
Amortized Cost	30,497,000	30,497,000
Unrealized Losses	(2,685,000)	(2,685,000)
Total held to maturity, Fair value,	27,812,000	27,812,000
Commercial - Government-sponsored enterprises
Available for sale debt securities
Amortized Cost	147,160,000	147,160,000	1,415,511,000
Unrealized Gains	918,000	918,000	2,646,000
Unrealized Losses	(6,242,000)	(6,242,000)	(48,714,000)
Total available-for-sale securities, Fair value,	141,836,000	141,836,000	1,369,443,000
Held to maturity securities
Amortized Cost	1,173,398,000	1,173,398,000
Unrealized Losses	(63,627,000)	(63,627,000)
Total held to maturity, Fair value,	1,109,771,000	1,109,771,000
Commercial - Non -agency
Available for sale debt securities
Amortized Cost	21,957,000	21,957,000
Unrealized Losses	(407,000)	(407,000)
Total available-for-sale securities, Fair value,	21,550,000	21,550,000
Government agency
Available for sale debt securities
Amortized Cost	1,102,277,000	1,102,277,000	2,103,187,000
Unrealized Gains			7,768,000
Unrealized Losses	(76,938,000)	(76,938,000)	(31,432,000)
Total available-for-sale securities, Fair value,	1,025,339,000	1,025,339,000	2,079,523,000
Held to maturity securities
Amortized Cost	879,010,000	879,010,000
Unrealized Losses	(31,243,000)	(31,243,000)
Total held to maturity, Fair value,	847,767,000	847,767,000
Government-sponsored enterprises
Available for sale debt securities
Amortized Cost	744,622,000	744,622,000	2,671,131,000
Unrealized Gains			3,608,000
Unrealized Losses	(60,062,000)	(60,062,000)	(53,695,000)
Total available-for-sale securities, Fair value,	684,560,000	684,560,000	2,621,044,000
Held to maturity securities
Amortized Cost	1,760,755,000	1,760,755,000
Unrealized Losses	(69,483,000)	(69,483,000)
Total held to maturity, Fair value,	1,691,272,000	1,691,272,000
Debt securities issued by states and political subdivisions
Available for sale debt securities
Amortized Cost			44,185,000
Total available-for-sale securities, Fair value,			$ 44,185,000
Held to maturity securities
Amortized Cost	53,640,000	53,640,000
Unrealized Losses	(3,844,000)	(3,844,000)
Total held to maturity, Fair value,	$ 49,796,000	$ 49,796,000