Investment Securities (Available For Sale Securities Unrealized Gains And Losses, By Security Type) (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 14,176,324,000	$ 14,419,133,000
Gross Unrealized Gains	574,000	163,823,000
Gross Unrealized Losses	(1,544,388,000)	(132,929,000)
Allowance for Credit Losses	0	0
Fair Value	12,632,510,000	14,450,027,000
U.S. government and federal agency obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,084,984,000	1,035,477,000
Gross Unrealized Gains	1,000	47,484,000
Gross Unrealized Losses	(48,660,000)	(2,241,000)
Allowance for Credit Losses	0	0
Fair Value	1,036,325,000	1,080,720,000
Government-sponsored enterprise obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	55,737,000	50,773,000
Gross Unrealized Gains	0	1,901,000
Gross Unrealized Losses	(12,562,000)	(919,000)
Allowance for Credit Losses	0	0
Fair Value	43,175,000	51,755,000
State and Municipal Obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,020,984,000	2,072,210,000
Gross Unrealized Gains	79,000	41,540,000
Gross Unrealized Losses	(217,810,000)	(16,923,000)
Allowance for Credit Losses	0	0
Fair Value	1,803,253,000	2,096,827,000
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,230,550,000	5,698,088,000
Gross Unrealized Gains	307,000	52,676,000
Gross Unrealized Losses	(785,338,000)	(67,764,000)
Allowance for Credit Losses	0	0
Fair Value	4,445,519,000	5,683,000,000
Non-Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,449,021,000	1,383,037,000
Gross Unrealized Gains	144,000	681,000
Gross Unrealized Losses	(213,581,000)	(17,241,000)
Allowance for Credit Losses	0	0
Fair Value	1,235,584,000	1,366,477,000
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,755,855,000	3,546,024,000
Gross Unrealized Gains	43,000	12,921,000
Gross Unrealized Losses	(197,611,000)	(19,726,000)
Allowance for Credit Losses	0	0
Fair Value	3,558,287,000	3,539,219,000
Total Mortgage And Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,435,426,000	10,627,149,000
Gross Unrealized Gains	494,000	66,278,000
Gross Unrealized Losses	(1,196,530,000)	(104,731,000)
Allowance for Credit Losses	0	0
Fair Value	9,239,390,000	10,588,696,000
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	579,193,000	633,524,000
Gross Unrealized Gains	0	6,620,000
Gross Unrealized Losses	(68,826,000)	(8,115,000)
Allowance for Credit Losses	0	0
Fair Value	$ 510,367,000	$ 632,029,000