Allowance for Loan and Lease Losses - Aging of Analysis of Past Due Loans and Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 35,736	$ 36,688
Current	12,106,101	11,474,260
Total Accruing Loans and Leases	12,141,837	11,510,948
Total NonAccruing Loans and Leases	7,874	9,430
Total loans and leases	12,149,711	11,520,378
30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	23,188	28,728
60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	4,601	4,692
Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	7,947	3,268
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due
Total Past Due	2,498	1,332
Current	3,185,427	3,235,538
Total Accruing Loans and Leases	3,187,925	3,236,870
Total NonAccruing Loans and Leases	2,312	2,730
Total loans and leases	3,190,237	3,239,600
Commercial and Industrial | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	179	720
Commercial and Industrial | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	568	163
Commercial and Industrial | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,751	449
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,331	475
Current	2,622,357	2,343,020
Total Accruing Loans and Leases	2,625,688	2,343,495
Total loans and leases	2,625,688	2,343,495
Commercial Real Estate | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		475
Commercial Real Estate | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	84
Commercial Real Estate | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,247
Construction
Financing Receivable, Recorded Investment, Past Due
Total Past Due	259
Current	598,504	450,012
Total Accruing Loans and Leases	598,763	450,012
Total loans and leases	598,763	450,012
Construction | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	259
Lease Financing
Financing Receivable, Recorded Investment, Past Due
Total Past Due		83
Current	171,373	179,804
Total Accruing Loans and Leases	171,373	179,887
Total NonAccruing Loans and Leases		153
Total loans and leases	171,373	180,040
Lease Financing | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		83
Residential
Financing Receivable, Recorded Investment, Past Due
Total Past Due	5,853	11,842
Current	3,990,063	3,778,070
Total Accruing Loans and Leases	3,995,916	3,789,912
Total NonAccruing Loans and Leases	5,562	6,547
Total loans and leases	4,001,478	3,796,459
Residential | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	4,588	9,907
Residential | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	210	1,069
Residential | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,055	866
Consumer
Financing Receivable, Recorded Investment, Past Due
Total Past Due	23,795	22,956
Current	1,538,377	1,487,816
Total Accruing Loans and Leases	1,562,172	1,510,772
Total loans and leases	1,562,172	1,510,772
Consumer | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	18,421	17,626
Consumer | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,480	3,460
Consumer | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 1,894	$ 1,870