Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 10,711,219	$ 8,581,829
Unrealized Loss, Less than 12 months	832,760	118,680
Fair Value, Greater than 12 months	1,730,123	465,833
Unrealized Loss, Greater than 12 months	259,362	14,249
Debt Securities, Available-for-sale, Unrealized Loss Position	12,441,342	9,047,662
Unrealized Loss on AFS Debt Securities	1,092,122	132,929
U.S. government and federal agency obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	609,636	296,492
Unrealized Loss, Less than 12 months	20,883	2,241
Fair Value, Greater than 12 months	0	0
Unrealized Loss, Greater than 12 months	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	609,636	296,492
Unrealized Loss on AFS Debt Securities	20,883	2,241
Government-sponsored enterprise obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	32,362	0
Unrealized Loss, Less than 12 months	3,577	0
Fair Value, Greater than 12 months	14,746	18,899
Unrealized Loss, Greater than 12 months	5,073	919
Debt Securities, Available-for-sale, Unrealized Loss Position	47,108	18,899
Unrealized Loss on AFS Debt Securities	8,650	919
State and Municipal Obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	1,239,029	876,691
Unrealized Loss, Less than 12 months	127,348	15,874
Fair Value, Greater than 12 months	137,304	32,684
Unrealized Loss, Greater than 12 months	24,739	1,049
Debt Securities, Available-for-sale, Unrealized Loss Position	1,376,333	909,375
Unrealized Loss on AFS Debt Securities	152,087	16,923
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	3,727,959	3,333,691
Unrealized Loss, Less than 12 months	351,355	59,044
Fair Value, Greater than 12 months	1,162,478	265,835
Unrealized Loss, Greater than 12 months	190,021	8,720
Debt Securities, Available-for-sale, Unrealized Loss Position	4,890,437	3,599,526
Unrealized Loss on AFS Debt Securities	541,376	67,764
Non-Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	1,295,069	1,285,611
Unrealized Loss, Less than 12 months	148,483	17,222
Fair Value, Greater than 12 months	26,541	1,948
Unrealized Loss, Greater than 12 months	3,469	19
Debt Securities, Available-for-sale, Unrealized Loss Position	1,321,610	1,287,559
Unrealized Loss on AFS Debt Securities	151,952	17,241
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	3,416,797	2,518,935
Unrealized Loss, Less than 12 months	152,152	19,201
Fair Value, Greater than 12 months	247,462	87,893
Unrealized Loss, Greater than 12 months	12,906	525
Debt Securities, Available-for-sale, Unrealized Loss Position	3,664,259	2,606,828
Unrealized Loss on AFS Debt Securities	165,058	19,726
Total Mortgage And Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	8,439,825	7,138,237
Unrealized Loss, Less than 12 months	651,990	95,467
Fair Value, Greater than 12 months	1,436,481	355,676
Unrealized Loss, Greater than 12 months	206,396	9,264
Debt Securities, Available-for-sale, Unrealized Loss Position	9,876,306	7,493,913
Unrealized Loss on AFS Debt Securities	858,386	104,731
Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	390,367	270,409
Unrealized Loss, Less than 12 months	28,962	5,098
Fair Value, Greater than 12 months	141,592	58,574
Unrealized Loss, Greater than 12 months	23,154	3,017
Debt Securities, Available-for-sale, Unrealized Loss Position	531,959	328,983
Unrealized Loss on AFS Debt Securities	$ 52,116	$ 8,115

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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