Derivatives and Hedging Activities (Derivative Financial Instruments included in OCI and Current Earnings) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	$ (3,383)	$ (2,729)	$ (11,559)	$ 20,452
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Loss on Termination of Derivatives, before Tax	0	(684)	0	(684)
Derivatives designated as hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain reclassified from OCI into interest income or interest expense (effective portion)	4,791	4,339	13,869	9,901
Derivative, Excluded Component, Gain (Loss), Recognized in Earnings	0	0	0	0
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Other income	(239)	2,020	(4,077)	4,647
Interest Expense [Member] | Derivatives designated as hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Excluded Component, Gain (Loss), Recognized in Earnings	0	0	0	0
Other expense | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Other income	54	21	137	46
Changes in fair value of mortgage derivatives | Derivatives designated as hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Excluded Component, Gain (Loss), Recognized in Earnings	0	0	0	0
Changes in fair value of mortgage derivatives | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Other income	(80)	(28)	(374)	(52)
Total | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Mortgage banking income	(213)	2,027	(3,840)	4,653
Derivatives designated as hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	$ (3,383)	$ (2,729)	$ (11,559)	$ 20,452