Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified											9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 Quoted Prices in Active Markets for Identical Assets (Level 1)	Sep. 30, 2012 Significant Other Observable Inputs (Level 2)	Dec. 31, 2011 Significant Other Observable Inputs (Level 2)	Sep. 30, 2012 Significant Unobservable Inputs (Level 3)	Dec. 31, 2011 Significant Unobservable Inputs (Level 3)	Sep. 30, 2012 Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2011 Estimate of Fair Value, Fair Value Disclosure [Member]	Sep. 30, 2012 Minimum [Member]	Sep. 30, 2012 Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	$ 3,678	$ 304	$ 0	$ 0	$ 3,678	$ 304	$ 0	$ 0	$ 3,678	$ 304
Liability derivatives	(2,067)	(976)	0	0	(2,067)	(976)	0	0	(2,067)	(976)
Bank acceptances			0		3,343		0		3,343
Rabbi trust assets			1,816	1,494	0	0	0	0	1,816	1,494
Financial assets and financial liabilities, reported at fair value			$ 1,816	$ 1,494	$ 4,954	$ (672)	$ 0	$ 0	$ 6,770	$ 822
Maturity of bank acceptances											3 months	6 months