Derivative Financial Instruments (Derivatives Used to Hedge Changes in Fair Value Attributable to Interest Rate Risk) (Details) - Fair value hedging - Designated as hedging instrument - Interest Rate Contract - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain Recognized in Income on Derivative	$ 704	$ 2,344
Amount Loss Recognized in Income on Hedged Item	(677)	(2,332)
Income Statement Gain due to Hedge Ineffectiveness	$ 27	$ 12