Derivatives (Currency Contracts) (Details) $ in Thousands, CAD in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015 CAD	Dec. 31, 2014 CAD
Derivative [Line Items]
Gain (loss) on derivatives not designated as hedging instruments	$ (158)	$ 403	$ (41)
Other Income (Expense) | Currency Contracts
Derivative [Line Items]
Gain (loss) on derivatives not designated as hedging instruments	$ (158)	$ 403	$ (41)
Not Designated as Hedging Instrument | Currency Contracts
Derivative [Line Items]
Derivative, notional amount | CAD				CAD 6.2	CAD 6.3