Derivative Financial Instruments (Net gains or losses) (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	$ 1,880	$ 5,587	$ 6,440	$ 10,344
Interest Rate Lock Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	1,550	4,154	4,472	8,113
Forward Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	(434)	(934)	(1,322)	(2,430)
Interest Rate Swap Agreements | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	10	1,595	690	2,416
Foreign Exchange Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	$ 754	$ 772	$ 2,600	$ 2,245