Allowance for Loan and Lease Losses - Aging of Analysis of Past Due Loans and Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 30,219	$ 35,360
Current	11,356,966	10,670,049
Total Accruing Loans and Leases	11,387,185	10,705,409
Total NonAccruing Loans and Leases	9,370	16,621
Total loans and leases	11,396,555	10,722,030
30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	20,702	25,573
60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	5,666	4,765
Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,851	5,022
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,862	2,766
Current	3,260,496	3,050,731
Total Accruing Loans and Leases	3,262,358	3,053,497
Total NonAccruing Loans and Leases	2,933	3,958
Total loans and leases	3,265,291	3,057,455
Commercial and Industrial | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,685	198
Commercial and Industrial | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		72
Commercial and Industrial | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	177	2,496
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due
Total Past Due	475	351
Current	2,311,399	2,163,959
Total Accruing Loans and Leases	2,311,874	2,164,310
Total NonAccruing Loans and Leases		138
Total loans and leases	2,311,874	2,164,448
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		190
Commercial Real Estate | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		161
Construction
Financing Receivable, Recorded Investment, Past Due
Total Past Due	251
Current	475,082	367,460
Total Accruing Loans and Leases	475,333	367,460
Total loans and leases	475,333	367,460
Construction | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	251
Lease Financing
Financing Receivable, Recorded Investment, Past Due
Total Past Due	82	215
Current	186,932	198,283
Total Accruing Loans and Leases	187,014	198,498
Total NonAccruing Loans and Leases	163	181
Total loans and leases	187,177	198,679
Lease Financing | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		41
Lease Financing | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	82
Lease Financing | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		174
Residential
Financing Receivable, Recorded Investment, Past Due
Total Past Due	8,262	12,327
Current	3,673,124	3,507,756
Total Accruing Loans and Leases	3,681,386	3,520,083
Total NonAccruing Loans and Leases	6,274	12,344
Total loans and leases	3,687,660	3,532,427
Residential | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	4,436	10,143
Residential | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	2,188	1,447
Residential | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,638	737
Consumer
Financing Receivable, Recorded Investment, Past Due
Total Past Due	19,287	19,701
Current	1,449,933	1,381,860
Total Accruing Loans and Leases	1,469,220	1,401,561
Total loans and leases	1,469,220	1,401,561
Consumer | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	13,855	15,191
Consumer | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,396	3,056
Consumer | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 2,036	$ 1,454