Derivatives and Hedging Activities (Derivative Financial Instruments included in OCI and Current Earnings) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent		$ 443	$ 2,170	$ 1,199
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Borrowings Expense, before Tax	[1]	(441)	(2,520)	(2,828)
Derivatives designated as hedges: [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			(2,520)	(2,828)
Derivatives not designated as hedges: [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income		(54)	(44)	(43)
Other Expense [Member] | Derivatives not designated as hedges: [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income		(21)	(82)	(53)
Other Income [Member] | Derivatives not designated as hedges: [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income		6	73	60
Mortgage banking income | Derivatives not designated as hedges: [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Increase Decrease In Fair Value Of Unhedged Derivative Instruments Relating To Residential Loans		(39)	(35)	(50)
Derivatives designated as hedges: [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent		$ 443	$ 2,170	$ 1,199

[1] Includes the amortization of the remaining balance of a realized but unrecognized gain, net of tax, from the termination of interest rate swaps in 2009. The original gain of $1.4 million, net of tax, will be recognized in earnings through December 2018, the original maturity date of the swap. The balance of this gain had amortized to $137,000, $281,000, and $427,000 at December 31, 2017, 2016, and 2015, respectively.