Derivative Instruments - Balance Sheet Location (Details) (Foreign Exchange Contract [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Other Current Assets [Member]
Offsetting Derivative Assets [Abstract]
Gross Amounts of Recognized Assets	$ 1,556	$ 5,744
Gross Amounts Offset in the Balance Sheet	(721)	(3,081)
Net Amounts Presented in Other Current Assets	835	2,663
Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross Amounts of Recognized Liabilities	5,870	4,289
Gross Amounts Offset Against Collateral	(2,703)	(3,281)
Net Amounts Presented in Other Current Liabilities	3,167	1,008
Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Offsetting Derivative Assets [Abstract]
Gross Amounts of Recognized Assets	0	3,019
Gross Amounts Offset in the Balance Sheet	0	(1,492)
Net Amounts Presented in Other Current Assets	0	1,527
Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross Amounts of Recognized Liabilities	2,081	0
Gross Amounts Offset Against Collateral	(742)	0
Net Amounts Presented in Other Current Liabilities	1,339	0
Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Offsetting Derivative Assets [Abstract]
Gross Amounts of Recognized Assets	1,556	2,725
Gross Amounts Offset in the Balance Sheet	(721)	(1,589)
Net Amounts Presented in Other Current Assets	835	1,136
Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross Amounts of Recognized Liabilities	3,789	4,289
Gross Amounts Offset Against Collateral	(1,961)	(3,281)
Net Amounts Presented in Other Current Liabilities	$ 1,828	$ 1,008