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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	$ 105,064	$ 104,677	$ 104,273	$ 102,880
Loans and Leases Charged-Off	(5,487)	(3,755)	(11,191)	(8,642)
Recoveries on Loans and Leases Previously Charged-Off	2,526	2,010	4,621	10,694
Net Loans and Leases Recovered (Charged-Off)	(2,961)	(1,745)	(6,570)	2,052
Provision for Credit Losses	4,250	1,000	8,650	(1,000)
Balance at End of Period	106,353	103,932	106,353	103,932
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment					$ 3,837		$ 3,202
Collectively Evaluated for Impairment					102,516		100,730
Total	105,064	104,677	104,273	102,880	106,353	$ 104,273	103,932
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment					58,725		60,962
Collectively Evaluated for Impairment					9,328,888		8,270,507
Total Loans and Leases					9,387,613	8,949,785	8,331,469
Commercial
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	66,893	61,810	65,680	60,714
Loans and Leases Charged-Off	(124)	(204)	(298)	(461)
Recoveries on Loans and Leases Previously Charged-Off	266	418	602	7,323
Net Loans and Leases Recovered (Charged-Off)	142	214	304	6,862
Provision for Credit Losses	(853)	5	198	(5,547)
Balance at End of Period	66,182	62,029	66,182	62,029
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment					45		7
Collectively Evaluated for Impairment					66,137		62,022
Total	66,893	61,810	65,680	60,714	66,182	65,680	62,029
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment					20,197		22,271
Collectively Evaluated for Impairment					3,684,715		3,283,571
Total Loans and Leases					3,704,912	3,617,692	3,305,842
Consumer
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	38,171	42,867	38,593	42,166
Loans and Leases Charged-Off	(5,363)	(3,551)	(10,893)	(8,181)
Recoveries on Loans and Leases Previously Charged-Off	2,260	1,592	4,019	3,371
Net Loans and Leases Recovered (Charged-Off)	(3,103)	(1,959)	(6,874)	(4,810)
Provision for Credit Losses	5,103	995	8,452	4,547
Balance at End of Period	40,171	41,903	40,171	41,903
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment					3,792		3,195
Collectively Evaluated for Impairment					36,379		38,708
Total	$ 38,171	$ 42,867	$ 38,593	$ 42,166	40,171	38,593	41,903
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment					38,528		38,691
Collectively Evaluated for Impairment					5,644,173		4,986,936
Total Loans and Leases					$ 5,682,701	$ 5,332,093	$ 5,025,627