Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 8,581,829	$ 694,458
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	118,680	3,741
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	465,833	253,734
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	14,249	2,617
Debt Securities, Available-for-sale, Unrealized Loss Position	9,047,662	948,192
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	132,929	6,358
US Treasury and Government [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	296,492	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,241	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	296,492	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	2,241	0
US Government-sponsored Enterprise Debt Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	19,720
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	98
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	18,899	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	919	0
Debt Securities, Available-for-sale, Unrealized Loss Position	18,899	19,720
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	919	98
State and municipal obligations [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	876,691	45,622
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	15,874	230
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	32,684	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,049	0
Debt Securities, Available-for-sale, Unrealized Loss Position	909,375	45,622
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	16,923	230
Agency mortgage-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	3,333,691	470,373
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	59,044	2,802
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	265,835	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	8,720	0
Debt Securities, Available-for-sale, Unrealized Loss Position	3,599,526	470,373
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	67,764	2,802
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,285,611	112,861
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	17,222	380
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,948	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	19	0
Debt Securities, Available-for-sale, Unrealized Loss Position	1,287,559	112,861
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	17,241	380
Asset-backed Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	2,518,935	21,360
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	19,201	56
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	87,893	253,734
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	525	2,617
Debt Securities, Available-for-sale, Unrealized Loss Position	2,606,828	275,094
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	19,726	2,673
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	7,138,237	604,594
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	95,467	3,238
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	355,676	253,734
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	9,264	2,617
Debt Securities, Available-for-sale, Unrealized Loss Position	7,493,913	858,328
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	104,731	5,855
Other debt securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	270,409	24,522
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5,098	175
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	58,574	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,017	0
Debt Securities, Available-for-sale, Unrealized Loss Position	328,983	24,522
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 8,115	$ 175

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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