Loans and Allowance for Loan Losses (Schedule of Allowances for Loan Losses and Recorded Investment in Loans) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Allowance for loan losses:
Beginning balance at March 31, 2021	$ 563,214	$ 493,452	$ 605,736	$ 281,402
Charge-offs	(30,853)	(30,778)	(56,178)	(54,652)
Recoveries	4,307	6,732	9,428	10,545
(Reversal of) provision for loan losses	(19,960)	119,242	(42,278)	268,359
Ending balance at June 30, 2021	516,708	588,648	516,708	588,648
Impact from Adoption
Allowance for loan losses:
Beginning balance at March 31, 2021				82,994
Adjusted balance
Allowance for loan losses:
Beginning balance at March 31, 2021				364,396
Commercial & Industrial
Allowance for loan losses:
Beginning balance at March 31, 2021	254,777	216,950	229,555	145,782
Charge-offs	(18,729)	(23,245)	(28,146)	(38,130)
Recoveries	1,495	3,261	4,267	5,002
(Reversal of) provision for loan losses	17,395	32,949	49,262	119,571
Ending balance at June 30, 2021	254,938	229,915	254,938	229,915
Commercial & Industrial | Impact from Adoption
Allowance for loan losses:
Beginning balance at March 31, 2021				(2,310)
Commercial & Industrial | Adjusted balance
Allowance for loan losses:
Beginning balance at March 31, 2021				143,472
Commercial Real Estate
Allowance for loan losses:
Beginning balance at March 31, 2021	113,812	107,117	130,742	67,430
Charge-offs	(3,839)	(689)	(14,158)	(1,706)
Recoveries	377	536	1,403	935
(Reversal of) provision for loan losses	(18,237)	64,562	(25,874)	105,518
Ending balance at June 30, 2021	92,113	171,526	92,113	171,526
Commercial Real Estate | Impact from Adoption
Allowance for loan losses:
Beginning balance at March 31, 2021				(651)
Commercial Real Estate | Adjusted balance
Allowance for loan losses:
Beginning balance at March 31, 2021				66,779
Consumer
Allowance for loan losses:
Beginning balance at March 31, 2021	194,625	169,385	245,439	68,190
Charge-offs	(8,285)	(6,844)	(13,874)	(14,816)
Recoveries	2,435	2,935	3,758	4,608
(Reversal of) provision for loan losses	(19,118)	21,731	(65,666)	43,270
Ending balance at June 30, 2021	$ 169,657	$ 187,207	$ 169,657	187,207
Consumer | Impact from Adoption
Allowance for loan losses:
Beginning balance at March 31, 2021				85,955
Consumer | Adjusted balance
Allowance for loan losses:
Beginning balance at March 31, 2021				$ 154,145