Investment Securities (Available For Sale Securities Unrealized Gains And Losses, By Security Type) (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 14,783,369,000	$ 14,419,133,000
Gross Unrealized Gains	9,061,000	163,823,000
Gross Unrealized Losses	(1,092,122,000)	(132,929,000)
Allowance for Credit Losses	0	0
Fair Value	13,700,308,000	14,450,027,000
U.S. government and federal agency obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,125,536,000	1,035,477,000
Gross Unrealized Gains	4,475,000	47,484,000
Gross Unrealized Losses	(20,883,000)	(2,241,000)
Allowance for Credit Losses	0	0
Fair Value	1,109,128,000	1,080,720,000
Government-sponsored enterprise obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	55,758,000	50,773,000
Gross Unrealized Gains	0	1,901,000
Gross Unrealized Losses	(8,650,000)	(919,000)
Allowance for Credit Losses	0	0
Fair Value	47,108,000	51,755,000
State and Municipal Obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,101,312,000	2,072,210,000
Gross Unrealized Gains	3,573,000	41,540,000
Gross Unrealized Losses	(152,087,000)	(16,923,000)
Allowance for Credit Losses	0	0
Fair Value	1,952,798,000	2,096,827,000
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,464,292,000	5,698,088,000
Gross Unrealized Gains	767,000	52,676,000
Gross Unrealized Losses	(541,376,000)	(67,764,000)
Allowance for Credit Losses	0	0
Fair Value	4,923,683,000	5,683,000,000
Non-Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,480,969,000	1,383,037,000
Gross Unrealized Gains	97,000	681,000
Gross Unrealized Losses	(151,952,000)	(17,241,000)
Allowance for Credit Losses	0	0
Fair Value	1,329,114,000	1,366,477,000
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,959,409,000	3,546,024,000
Gross Unrealized Gains	136,000	12,921,000
Gross Unrealized Losses	(165,058,000)	(19,726,000)
Allowance for Credit Losses	0	0
Fair Value	3,794,487,000	3,539,219,000
Total Mortgage And Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,904,670,000	10,627,149,000
Gross Unrealized Gains	1,000,000	66,278,000
Gross Unrealized Losses	(858,386,000)	(104,731,000)
Allowance for Credit Losses	0	0
Fair Value	10,047,284,000	10,588,696,000
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	596,093,000	633,524,000
Gross Unrealized Gains	13,000	6,620,000
Gross Unrealized Losses	(52,116,000)	(8,115,000)
Allowance for Credit Losses	0	0
Fair Value	$ 543,990,000	$ 632,029,000