Derivative Financial Instruments (Derivatives not Designated as Hedging Instruments, Effect in Statements of Income) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	$ (1,068)	$ 1,291	$ 2,155	$ 3,848
Interest rate swaps with customers [Member] | Loan related derivative income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	11,665	7,960	(18,566)	66,491
Mirror swaps with counterparties [Member] | Loan related derivative income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(11,068)	(7,964)	19,615	(64,154)
Risk participation agreements [Member] | Loan related derivative income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	578	103	593	217
Interest rate lock commitments [Member] | Mortgage banking revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(313)	3,548	(4,842)	7,284
Forward sale commitments [Member] | Mortgage banking revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	$ (1,930)	$ (2,356)	$ 5,355	$ (5,990)