Derivative Financial Instruments (Net gains or losses) (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains (Losses) Recognized in the Statements of Income	$ 19,455	$ 8,353	$ 8,362
Interest Rate Lock Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains (Losses) Recognized in the Statements of Income	12,185	3,534	5,643
Forward Commitments | Mortgage Banking Income
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains (Losses) Recognized in the Statements of Income	(2,340)	821	(1,275)
Interest Rate Swap Agreements | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains (Losses) Recognized in the Statements of Income	7,172	1,835	698
Foreign Exchange Contracts | Other Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains (Losses) Recognized in the Statements of Income	2,891	3,163	3,296
Visa Conversion Rate Swap Agreement [Member] | Gain (Loss) on Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains (Losses) Recognized in the Statements of Income	$ (453)	$ (1,000)	$ 0