Derivatives (Effects of Derivative Instruments on the Statements of Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement	$ 13,073	$ 11,254
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	1,192	5,035
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	6,754	6,136
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	1,158	$ 83
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedging [Member] | Securities Transactions Net [Member] | Securities Termination [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement	1,620
Derivatives Not Designated as Hedging Instruments [Member] | Secondary Mortgage Market Operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income reflected in income statement	$ (2,349)