Allowance for Loan and Lease Losses - Aging of Analysis of Past Due Loans and Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 28,106	$ 35,360
Current	11,146,263	10,670,049
Total Accruing Loans and Leases	11,174,369	10,705,409
Total NonAccruing Loans and Leases	13,326	16,621
Total loans and leases	11,187,695	10,722,030
30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	21,097	25,573
60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	4,107	4,765
Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	2,902	5,022
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due
Total Past Due		2,766
Current	3,284,905	3,050,731
Total Accruing Loans and Leases	3,284,905	3,053,497
Total NonAccruing Loans and Leases	3,598	3,958
Total loans and leases	3,288,503	3,057,455
Commercial and Industrial | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		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		2,496
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due
Total Past Due	576	351
Current	2,181,156	2,163,959
Total Accruing Loans and Leases	2,181,732	2,164,310
Total NonAccruing Loans and Leases		138
Total loans and leases	2,181,732	2,164,448
Commercial Real Estate | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	576
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
Current	424,419	367,460
Total Accruing Loans and Leases	424,419	367,460
Total NonAccruing Loans and Leases	324
Total loans and leases	424,743	367,460
Lease Financing
Financing Receivable, Recorded Investment, Past Due
Total Past Due		215
Current	185,931	198,283
Total Accruing Loans and Leases	185,931	198,498
Total NonAccruing Loans and Leases	173	181
Total loans and leases	186,104	198,679
Lease Financing | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		41
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	8,514	12,327
Current	3,636,780	3,507,756
Total Accruing Loans and Leases	3,645,294	3,520,083
Total NonAccruing Loans and Leases	9,231	12,344
Total loans and leases	3,654,525	3,532,427
Residential | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	6,008	10,143
Residential | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,172	1,447
Residential | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,334	737
Consumer
Financing Receivable, Recorded Investment, Past Due
Total Past Due	19,016	19,701
Current	1,433,072	1,381,860
Total Accruing Loans and Leases	1,452,088	1,401,561
Total loans and leases	1,452,088	1,401,561
Consumer | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	14,513	15,191
Consumer | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	2,935	3,056
Consumer | Greater Than or Equal to 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 1,568	$ 1,454