Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 4,159,679	$ 3,195,732
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	286,863	43,236
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	516,421	383,754
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	50,604	14,645
Debt Securities, Available-for-sale, Unrealized Loss Position	4,676,100	3,579,486
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	337,467	57,881
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	2,667,464	2,292,062
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	181,337	30,777
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	214,390	176,946
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	23,900	7,315
Debt Securities, Available-for-sale, Unrealized Loss Position	2,881,854	2,469,008
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	205,237	38,092
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	277,210	195,708
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	16,208	4,823
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	106,449	117,751
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	10,001	4,968
Debt Securities, Available-for-sale, Unrealized Loss Position	383,659	313,459
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	26,209	9,791
State and Municipal Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	657,101	237,354
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	57,012	3,862
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	77,447	40,343
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	8,788	1,076
Debt Securities, Available-for-sale, Unrealized Loss Position	734,548	277,697
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	65,800	4,938
U.S. Government and Government-Sponsored Enterprise Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	25,502	100,813
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,249	1,988
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	118,135	48,714
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	7,915	1,286
Debt Securities, Available-for-sale, Unrealized Loss Position	143,637	149,527
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	9,164	3,274
US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	173,342	157,536
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	9,158	831
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	173,342	157,536
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	9,158	831
Non-agency collateralized mortgage obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	359,060	212,259
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	21,899	955
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	359,060	212,259
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 21,899	$ 955

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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