Derivatives (Currency Contracts) (Details) $ in Thousands, CAD in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2016 CAD	Dec. 31, 2015 CAD
Derivative [Line Items]
Gain (loss) on derivatives not designated as hedging instruments	$ (418)	$ 74
Other Income (Expense) [Member] | Currency contracts [Member]
Derivative [Line Items]
Gain (loss) on derivatives not designated as hedging instruments	$ (418)	$ 74
Not Designated as Hedging Instrument [Member] | Currency contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount | CAD			CAD 7.0	CAD 6.2