Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 239,315	$ 99,075
Unrealized Loss, Less than 12 months	2,717	1,784
Fair Value, Greater than 12 months	8,824,012	9,494,875
Unrealized Loss, Greater than 12 months	1,244,901	1,218,700
Debt Securities, Available-for-sale, Unrealized Loss Position	9,063,327	9,593,950
Unrealized Loss on AFS Debt Securities	1,247,618	1,220,484
U.S. government and federal agency obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	223,026	51,585
Unrealized Loss, Less than 12 months	1,971	809
Fair Value, Greater than 12 months	502,312	714,400
Unrealized Loss, Greater than 12 months	21,049	24,025
Debt Securities, Available-for-sale, Unrealized Loss Position	725,338	765,985
Unrealized Loss on AFS Debt Securities	23,020	24,834
Government-sponsored enterprise obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	0	0
Unrealized Loss, Less than 12 months	0	0
Fair Value, Greater than 12 months	43,845	43,962
Unrealized Loss, Greater than 12 months	11,792	11,696
Debt Securities, Available-for-sale, Unrealized Loss Position	43,845	43,962
Unrealized Loss on AFS Debt Securities	11,792	11,696
State and municipal obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	9,675	24,022
Unrealized Loss, Less than 12 months	703	760
Fair Value, Greater than 12 months	1,113,829	1,167,607
Unrealized Loss, Greater than 12 months	146,839	148,478
Debt Securities, Available-for-sale, Unrealized Loss Position	1,123,504	1,191,629
Unrealized Loss on AFS Debt Securities	147,542	149,238
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	2,907	4,382
Unrealized Loss, Less than 12 months	35	59
Fair Value, Greater than 12 months	3,732,370	3,875,432
Unrealized Loss, Greater than 12 months	769,632	720,649
Debt Securities, Available-for-sale, Unrealized Loss Position	3,735,277	3,879,814
Unrealized Loss on AFS Debt Securities	769,667	720,708
Non-Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	0	0
Unrealized Loss, Less than 12 months	0	0
Fair Value, Greater than 12 months	1,133,805	1,152,045
Unrealized Loss, Greater than 12 months	170,644	173,526
Debt Securities, Available-for-sale, Unrealized Loss Position	1,133,805	1,152,045
Unrealized Loss on AFS Debt Securities	170,644	173,526
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	3,707	19,086
Unrealized Loss, Less than 12 months	8	156
Fair Value, Greater than 12 months	1,853,484	2,081,293
Unrealized Loss, Greater than 12 months	76,356	93,076
Debt Securities, Available-for-sale, Unrealized Loss Position	1,857,191	2,100,379
Unrealized Loss on AFS Debt Securities	76,364	93,232
Total Mortgage And Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	6,614	23,468
Unrealized Loss, Less than 12 months	43	215
Fair Value, Greater than 12 months	6,719,659	7,108,770
Unrealized Loss, Greater than 12 months	1,016,632	987,251
Debt Securities, Available-for-sale, Unrealized Loss Position	6,726,273	7,132,238
Unrealized Loss on AFS Debt Securities	1,016,675	987,466
Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	0	0
Unrealized Loss, Less than 12 months	0	0
Fair Value, Greater than 12 months	444,367	460,136
Unrealized Loss, Greater than 12 months	48,589	47,250
Debt Securities, Available-for-sale, Unrealized Loss Position	444,367	460,136
Unrealized Loss on AFS Debt Securities	$ 48,589	$ 47,250