Derivative Financial Instruments (Net gains or losses) (Details 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	$ 5,091	$ 1,835	$ 8,274	$ 4,132
Interest Rate Lock Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	3,561	968	5,286	1,498
Forward Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	(1,382)	240	(1,974)	925
Interest Rate Swap Agreements | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	1,760	632	2,896	750
Foreign Exchange Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	1,152	995	2,066	1,959
Visa Conversion Rate Swap Agreement | Gain (Loss) on Investments [Member]
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	$ 0	$ (1,000)	$ 0	$ (1,000)