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
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	$ 104,273	$ 102,880
Loans and Leases Charged-Off	(5,704)	(4,887)
Recoveries on Loans and Leases Previously Charged-Off	2,095	8,684
Net Loans and Leases Recovered (Charged-Off)	(3,609)	3,797
Provision for Credit Losses	4,400	(2,000)
Balance at End of Period	105,064	104,677
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment			$ 3,950		$ 3,563
Collectively Evaluated for Impairment			101,114		101,114
Total	104,273	102,880	105,064	$ 104,273	104,677
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment			60,331		62,014
Collectively Evaluated for Impairment			9,053,478		8,003,596
Total Loans and Leases			9,113,809	8,949,785	8,065,610
Commercial
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	65,680	60,714
Loans and Leases Charged-Off	(174)	(257)
Recoveries on Loans and Leases Previously Charged-Off	336	6,905
Net Loans and Leases Recovered (Charged-Off)	162	6,648
Provision for Credit Losses	1,051	(5,552)
Balance at End of Period	66,893	61,810
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment			38		157
Collectively Evaluated for Impairment			66,855		61,653
Total	65,680	60,714	66,893	65,680	61,810
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment			20,902		22,986
Collectively Evaluated for Impairment			3,609,593		3,233,267
Total Loans and Leases			3,630,495	3,617,692	3,256,253
Consumer
Allowance for Loan and Lease Losses:
Balance at Beginning of Period	38,593	42,166
Loans and Leases Charged-Off	(5,530)	(4,630)
Recoveries on Loans and Leases Previously Charged-Off	1,759	1,779
Net Loans and Leases Recovered (Charged-Off)	(3,771)	(2,851)
Provision for Credit Losses	3,349	3,552
Balance at End of Period	38,171	42,867
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment			3,912		3,406
Collectively Evaluated for Impairment			34,259		39,461
Total	$ 38,593	$ 42,166	38,171	38,593	42,867
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment			39,429		39,028
Collectively Evaluated for Impairment			5,443,885		4,770,329
Total Loans and Leases			$ 5,483,314	$ 5,332,093	$ 4,809,357