Basis of Presentation and Accounting Policies (Schedule of Adoption) (Details) - USD ($) $ in Thousands		6 Months Ended
	Jan. 01, 2020	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201602Member
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	$ 281,402	$ 588,648	$ 257,376	$ 493,452	$ 281,402	$ 257,036	$ 250,555
Reserve for unfunded commitments	1,375
Allowance for credit losses	282,777	649,700
Loans, net	36,881,048
Retained earnings	1,068,327	1,050,527			1,068,327
Total commercial and industrial
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	145,782	229,915	138,004	216,950		135,639	133,123
Total commercial real estate
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	67,430	171,526	63,463	107,117		69,009	68,796
Retail
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	68,190	$ 187,207	$ 55,909	$ 169,385		$ 52,388	$ 48,636
Impact of ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	82,994				82,994
Reserve for unfunded commitments	27,440
Allowance for credit losses	110,434
Loans, net	(20,767)
Retained earnings	(35,721)
Impact of ASC 326 Adoption | Total commercial and industrial
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	(2,310)				(2,310)
Impact of ASC 326 Adoption | Total commercial real estate
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	(651)				(651)
Impact of ASC 326 Adoption | Retail
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	85,955				$ 85,955
As Reported under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	364,396
Reserve for unfunded commitments	28,815
Allowance for credit losses	393,211
Loans, net	36,860,281
Retained earnings	1,032,606
As Reported under ASC 326 | Total commercial and industrial
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	143,472
As Reported under ASC 326 | Total commercial real estate
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	66,779
As Reported under ASC 326 | Retail
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total allowance for loan losses	$ 154,145