Derivatives (Effects of Derivative Instruments on the Statements of Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement	$ 10,380	$ 16,466	$ 23,453	$ 27,720
Derivatives Designated as Hedging Instruments [Member] | Other Noninterest Income [Member] | Customer and All Other Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement	1,768	3,472	2,960	3,472
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedge [Member] | Interest Income [Member] | Interest Rate Swaps - Variable Rate Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement	6,013	6,855	12,767	12,991
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedging [Member] | Interest Income [Member] | Interest Rate Swaps - Securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement	(129)	(110)	1,029	(27)
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedging [Member] | Securities Transactions Net [Member] | Interest Rate Swaps - Securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement		2,499	1,620	2,499
Derivatives Not Designated as Hedging Instruments [Member] | Secondary Mortgage Market Operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement	$ 2,728	$ 3,750	$ 5,077	$ 8,785