Loans and Leases and the Allowance for Loan and Lease Losses (Allowance for Loan and Lease Losses) (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	$ 106,023	$ 107,938	$ 106,693	$ 107,346
Loans and Leases Charged-Off	(5,129)	(5,661)	(11,957)	(11,649)
Recoveries on Loans and Leases Previously Charged-Off	2,778	2,411	5,936	4,866
Net Loans and Leases Recovered (Charged-Off)	(2,351)	(3,250)	(6,021)	(6,783)
Provision for Credit Losses	4,000	3,500	7,000	7,625
Balance at End of Period	107,672	108,188	107,672	108,188
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment					$ 4,043		$ 3,927
Collectively Evaluated for Impairment					103,629		104,261
Total	106,023	107,938	106,693	108,188	107,672	$ 106,693	108,188
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment					62,762		54,165
Collectively Evaluated for Impairment					10,696,367		9,999,158
Total Loans and Leases					10,759,129	10,448,774	10,053,323
Commercial
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	67,527	64,110	66,874	65,822
Loans and Leases Charged-Off	(206)	(485)	(2,192)	(691)
Recoveries on Loans and Leases Previously Charged-Off	401	366	902	694
Net Loans and Leases Recovered (Charged-Off)	195	(119)	(1,290)	3
Provision for Credit Losses	1,546	(279)	3,684	(2,113)
Balance at End of Period	69,268	63,712	69,268	63,712
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment					716		100
Collectively Evaluated for Impairment					68,552		63,612
Total	67,527	64,110	69,268	65,822	69,268	66,874	63,712
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment					20,791		12,184
Collectively Evaluated for Impairment					4,081,525		3,804,088
Total Loans and Leases					4,102,316	3,979,792	3,816,272
Consumer
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	38,496	43,828	39,819	41,524
Loans and Leases Charged-Off	(4,923)	(5,176)	(9,765)	(10,958)
Recoveries on Loans and Leases Previously Charged-Off	2,377	2,045	5,034	4,172
Net Loans and Leases Recovered (Charged-Off)	(2,546)	(3,131)	(4,731)	(6,786)
Provision for Credit Losses	2,454	3,779	3,316	9,738
Balance at End of Period	38,404	44,476	38,404	44,476
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment					3,327		3,827
Collectively Evaluated for Impairment					35,077		40,649
Total	$ 38,496	$ 43,828	$ 39,819	$ 41,524	38,404	39,819	44,476
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment					41,971		41,981
Collectively Evaluated for Impairment					6,614,842		6,195,070
Total Loans and Leases					$ 6,656,813	$ 6,468,982	$ 6,237,051