Derivative Financial Instruments (Schedule of Fair Value of Derivative Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Assets	$ 48,985	$ 49,213
Derivative Liabilities	33,716	37,665
Other Liabilities
Derivative [Line Items]
Derivative Assets	52,069	56,394
Derivative Liabilities	35,671	39,839
Designated as hedging instrument | Other Liabilities
Derivative [Line Items]
Derivative Assets	14,846	10,239
Derivative Liabilities	12	0
Not designed as hedging instrument | Other Liabilities
Derivative [Line Items]
Derivative Assets	37,223	46,155
Derivative Liabilities	35,659	39,839
Not designed as hedging instrument | Interest Rate Derivatives | Other Liabilities
Derivative [Line Items]
Derivative Assets	34,139	38,974
Derivative Liabilities	33,704	37,665
Not designed as hedging instrument | Interest Rate Lock Commitments | Other Liabilities
Derivative [Line Items]
Derivative Assets	2,843	4,265
Derivative Liabilities	269	1,325
Not designed as hedging instrument | Forward commitments to sell mortgage loans | Other Liabilities
Derivative [Line Items]
Derivative Assets	14	2,037
Derivative Liabilities	1,457	0
Not designed as hedging instrument | Foreign Exchange Contract | Other Liabilities
Derivative [Line Items]
Derivative Assets	227	879
Derivative Liabilities	229	849
Cash flow hedging | Designated as hedging instrument | Interest Rate Derivatives | Other Liabilities
Derivative [Line Items]
Derivative Assets	11,914	8,011
Derivative Liabilities	12	0
Fair value hedging | Designated as hedging instrument | Interest Rate Derivatives | Other Liabilities
Derivative [Line Items]
Derivative Assets	2,932	2,228
Derivative Liabilities	$ 0	$ 0