Loans (Loans, Net of Unearned Income) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 16,752,151	$ 15,703,314
Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	12,545,507	11,560,325
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,146,713	2,049,524
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,059,931	2,093,465
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,013,890	1,553,082
Construction and Land Development [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,010,879	1,151,950
Total Commercial & Industrial [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	9,520,738	8,855,293
Total Commercial & Industrial [Member] | Commercial Non-Real Estate [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	7,613,917	6,995,824
Total Commercial & Industrial [Member] | Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 1,906,821	$ 1,859,469