Derivatives (Primary Risks) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Gross Notional Amount	$ 47,986	$ 47,993
Estimated Fair Value Assets	7,896	8,656
Estimated Fair Value Liabilities	0	0
Derivatives Designated as Hedging Instruments: | Cash Flow Hedges | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	33,923	33,930
Estimated Fair Value Assets	4,526	4,947
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gross Notional Amount	14,063	14,063
Estimated Fair Value Assets	3,370	3,709
Estimated Fair Value Liabilities	$ 0	$ 0