Derivatives and Hedging Activities (Derivative Positions for Interest Rate Swaps which Qualify as Hedges) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Details of derivative positions for interest rate swaps which qualify as hedges for accounting purposes
Amortization Of Deferred Hedge Gains Losses		$ 0	$ 0	$ 231
Notional amount of fair value hedged derivative				$ 0
Interest rate swaps on borrowings [Member]
Details of derivative positions for interest rate swaps which qualify as hedges for accounting purposes
Fair Value	[1]	(1,341)	140
Derivative, Notional Amount		$ 75,000	$ 75,000
Derivative, Average Remaining Maturity		1 year 2 months 4 days	2 years 2 months 4 days
Derivative, Average Variable Interest Rate		0.22%	1.90%
Derivative, Average Fixed Interest Rate		1.53%	1.53%
Interest rate swaps on loans [Member]
Details of derivative positions for interest rate swaps which qualify as hedges for accounting purposes
Fair Value	[1]	$ 27,021	$ 12,907
Derivative, Notional Amount		$ 450,000	$ 450,000
Derivative, Average Remaining Maturity		2 years 7 months 28 days	3 years 7 months 28 days
Derivative, Average Variable Interest Rate		0.15%	1.76%
Derivative, Average Fixed Interest Rate		2.37%	2.37%
Interest rate collars on loans [Member]
Details of derivative positions for interest rate swaps which qualify as hedges for accounting purposes
Fair Value	[1]	$ 21,764	$ 9,896
Derivative, Notional Amount		$ 400,000	$ 400,000
Derivative, Average Remaining Maturity		2 years 7 months 28 days	3 years 7 months 28 days
Derivative, Average Variable Interest Rate		0.15%	1.76%
Derivative, Cap Interest Rate		2.73%	2.73%
Derivative, Floor Interest Rate		2.20%	2.02%
Interest Rate Swap [Member]
Details of derivative positions for interest rate swaps which qualify as hedges for accounting purposes
Fair Value	[1]	$ 47,444	$ 22,943
Derivative, Notional Amount		$ 925,000	$ 925,000

[1] Beginning in 2020, the Company made an election to include accrued interest within fair value balances.