Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Liabilities	$ (976)	$ (667)
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	0	0
Derivative Liabilities	0	0
Rabbi Trust Asset Fair Value Disclosure	1,494	1,350
Financial Instruments Asset Liabilities at Fair Value Net	1,494	1,350
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	304	1,617
Derivative Liabilities	(976)	(667)
Rabbi Trust Asset Fair Value Disclosure	0	0
Financial Instruments Asset Liabilities at Fair Value Net	(672)	950
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	0	0
Derivative Liabilities	0	0
Rabbi Trust Asset Fair Value Disclosure	0	0
Financial Instruments Asset Liabilities at Fair Value Net	0	0
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	304	1,617
Derivative Liabilities	(976)	(667)
Rabbi Trust Asset Fair Value Disclosure	1,494	1,350
Financial Instruments Asset Liabilities at Fair Value Net	$ 822	$ 2,300