Derivative Financial Instruments (Net gains or losses) (Details 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	$ 2,511	$ 3,433	$ 4,559	$ 4,758
Interest Rate Lock Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	1,655	2,973	2,922	3,959
Forward Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	(465)	(1,017)	(889)	(1,496)
Interest Rate Swap Agreements | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	525	713	680	822
Foreign Exchange Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	$ 796	$ 764	$ 1,846	$ 1,473