Derivatives (Currency Contracts) (Details) $ in Thousands, CAD in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 CAD	Dec. 31, 2014 CAD
Derivative [Line Items]
Gain (loss) on derivatives not designated as hedging instruments	$ 135	$ 461	$ (152)	$ 274
Other Income (Expense) [Member] | Currency contracts [Member]
Derivative [Line Items]
Gain (loss) on derivatives not designated as hedging instruments	$ 135	$ 461	$ (152)	$ 274
Not Designated as Hedging Instrument [Member] | Currency contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount | CAD					CAD 6.3	CAD 6.3