Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 395,982	$ 99,075
Unrealized Loss, Less than 12 months	2,406	1,784
Fair Value, Greater than 12 months	6,878,350	9,494,875
Unrealized Loss, Greater than 12 months	816,408	1,218,700
Debt Securities, Available-for-sale, Unrealized Loss Position	7,274,332	9,593,950
Unrealized Loss on AFS Debt Securities	818,814	1,220,484
U.S. government and federal agency obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	359,913	51,585
Unrealized Loss, Less than 12 months	851	809
Fair Value, Greater than 12 months	357,083	714,400
Unrealized Loss, Greater than 12 months	12,528	24,025
Debt Securities, Available-for-sale, Unrealized Loss Position	716,996	765,985
Unrealized Loss on AFS Debt Securities	13,379	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	45,499	43,962
Unrealized Loss, Greater than 12 months	9,934	11,696
Debt Securities, Available-for-sale, Unrealized Loss Position	45,499	43,962
Unrealized Loss on AFS Debt Securities	9,934	11,696
State and municipal obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	7,676	24,022
Unrealized Loss, Less than 12 months	476	760
Fair Value, Greater than 12 months	756,489	1,167,607
Unrealized Loss, Greater than 12 months	66,715	148,478
Debt Securities, Available-for-sale, Unrealized Loss Position	764,165	1,191,629
Unrealized Loss on AFS Debt Securities	67,191	149,238
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	314	4,382
Unrealized Loss, Less than 12 months	1	59
Fair Value, Greater than 12 months	3,636,235	3,875,432
Unrealized Loss, Greater than 12 months	622,281	720,649
Debt Securities, Available-for-sale, Unrealized Loss Position	3,636,549	3,879,814
Unrealized Loss on AFS Debt Securities	622,282	720,708
Non-Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	27	0
Unrealized Loss, Less than 12 months	0	0
Fair Value, Greater than 12 months	604,980	1,152,045
Unrealized Loss, Greater than 12 months	54,228	173,526
Debt Securities, Available-for-sale, Unrealized Loss Position	605,007	1,152,045
Unrealized Loss on AFS Debt Securities	54,228	173,526
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	28,052	19,086
Unrealized Loss, Less than 12 months	1,078	156
Fair Value, Greater than 12 months	1,273,016	2,081,293
Unrealized Loss, Greater than 12 months	39,177	93,076
Debt Securities, Available-for-sale, Unrealized Loss Position	1,301,068	2,100,379
Unrealized Loss on AFS Debt Securities	40,255	93,232
Total Mortgage And Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	28,393	23,468
Unrealized Loss, Less than 12 months	1,079	215
Fair Value, Greater than 12 months	5,514,231	7,108,770
Unrealized Loss, Greater than 12 months	715,686	987,251
Debt Securities, Available-for-sale, Unrealized Loss Position	5,542,624	7,132,238
Unrealized Loss on AFS Debt Securities	716,765	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	205,048	460,136
Unrealized Loss, Greater than 12 months	11,545	47,250
Debt Securities, Available-for-sale, Unrealized Loss Position	205,048	460,136
Unrealized Loss on AFS Debt Securities	$ 11,545	$ 47,250