Loans (Summary of Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 17,118,117	$ 14,409,398
Covered loans	148,673	226,709
Total loans	$ 17,266,790	$ 14,636,107
Total loans, percentage	99.00%	98.00%
Covered loans, percentage	1.00%	2.00%
Percentage of Loans Net of Unearned Income Including Covered Loans	100.00%	100.00%
Commercial
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 4,713,909	$ 3,924,394
Total loans, percentage	27.00%	26.00%
Commercial real estate
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 5,529,289	$ 4,505,753
Total loans, percentage	32.00%	31.00%
Home equity
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 784,675	$ 716,293
Total loans, percentage	5.00%	5.00%
Residential real estate
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 607,451	$ 483,542
Total loans, percentage	3.00%	3.00%
Premium finance receivables | Life insurance
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 2,961,496	$ 2,277,571
Total loans, percentage	17.00%	16.00%
Premium finance receivables | Commercial insurance loans
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 2,374,921	$ 2,350,833
Total loans, percentage	14.00%	16.00%
Consumer and other
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 146,376	$ 151,012
Total loans, percentage	1.00%	1.00%