Derivatives (Gains and Losses for Derivatives that were Not Designated as Hedging Instruments) (Details)	3 Months Ended
	Mar. 31, 2013 USD ($)	Mar. 31, 2012 USD ($)	Mar. 31, 2013 Other Income (Expense) [Member] Currency contracts [Member] USD ($)	Mar. 31, 2012 Other Income (Expense) [Member] Currency contracts [Member] USD ($)	Mar. 31, 2013 Not Designated as Hedging Instrument [Member] Currency contracts [Member] CAD	Dec. 31, 2012 Not Designated as Hedging Instrument [Member] Currency contracts [Member] CAD
Derivative [Line Items]
Derivative, notional amount					11,700,000	14,800,000
Gain and losses for derivatives not designated as hedging instruments	$ 251,000	$ (162,000)	$ 251,000	$ (162,000)