Derivative Financial Instruments (Net gains or losses) (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	$ 11,271	$ 3,183
Interest Rate Lock Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	6,303	1,725
Forward Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	(2,184)	(592)
Interest Rate Swap Agreements | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	6,438	1,136
Foreign Exchange Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss)
Net gains (losses) recognized in the statements of income	$ 714	$ 914