Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 514,254	$ 4,402,724
Unrealized Loss, Less than 12 months	20,137	250,660
Fair Value, Greater than 12 months	9,856,744	7,625,021
Unrealized Loss, Greater than 12 months	1,399,256	1,249,972
Debt Securities, Available-for-sale, Unrealized Loss Position	10,370,998	12,027,745
Unrealized Loss on AFS Debt Securities	1,419,393	1,500,632
U.S. government and federal agency obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	355,274	605,840
Unrealized Loss, Less than 12 months	15,192	17,490
Fair Value, Greater than 12 months	590,541	380,573
Unrealized Loss, Greater than 12 months	23,977	25,940
Debt Securities, Available-for-sale, Unrealized Loss Position	945,815	986,413
Unrealized Loss on AFS Debt Securities	39,169	43,430
Government-sponsored enterprise obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	0	25,068
Unrealized Loss, Less than 12 months	0	4,650
Fair Value, Greater than 12 months	44,036	18,040
Unrealized Loss, Greater than 12 months	11,645	7,971
Debt Securities, Available-for-sale, Unrealized Loss Position	44,036	43,108
Unrealized Loss on AFS Debt Securities	11,645	12,621
State and municipal obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	82,322	814,799
Unrealized Loss, Less than 12 months	1,999	26,708
Fair Value, Greater than 12 months	1,140,008	875,329
Unrealized Loss, Greater than 12 months	171,874	171,385
Debt Securities, Available-for-sale, Unrealized Loss Position	1,222,330	1,690,128
Unrealized Loss on AFS Debt Securities	173,873	198,093
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	50,830	1,323,938
Unrealized Loss, Less than 12 months	2,159	125,330
Fair Value, Greater than 12 months	4,000,228	2,966,851
Unrealized Loss, Greater than 12 months	781,734	654,327
Debt Securities, Available-for-sale, Unrealized Loss Position	4,051,058	4,290,789
Unrealized Loss on AFS Debt Securities	783,893	779,657
Non-Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	1,106	135,984
Unrealized Loss, Less than 12 months	9	16,736
Fair Value, Greater than 12 months	1,168,007	1,069,222
Unrealized Loss, Greater than 12 months	203,789	195,218
Debt Securities, Available-for-sale, Unrealized Loss Position	1,169,113	1,205,206
Unrealized Loss on AFS Debt Securities	203,798	211,954
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	23,848	1,331,055
Unrealized Loss, Less than 12 months	652	50,056
Fair Value, Greater than 12 months	2,457,632	2,006,188
Unrealized Loss, Greater than 12 months	146,649	140,424
Debt Securities, Available-for-sale, Unrealized Loss Position	2,481,480	3,337,243
Unrealized Loss on AFS Debt Securities	147,301	190,480
Total Mortgage And Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	75,784	2,790,977
Unrealized Loss, Less than 12 months	2,820	192,122
Fair Value, Greater than 12 months	7,625,867	6,042,261
Unrealized Loss, Greater than 12 months	1,132,172	989,969
Debt Securities, Available-for-sale, Unrealized Loss Position	7,701,651	8,833,238
Unrealized Loss on AFS Debt Securities	1,134,992	1,182,091
Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	874	166,040
Unrealized Loss, Less than 12 months	126	9,690
Fair Value, Greater than 12 months	456,292	308,818
Unrealized Loss, Greater than 12 months	59,588	54,707
Debt Securities, Available-for-sale, Unrealized Loss Position	457,166	474,858
Unrealized Loss on AFS Debt Securities	$ 59,714	$ 64,397