Fair Value Measurements (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Derivative Liabilities	$ (316)	$ (667)
3.375% Convertible Notes [Member]
Convertible Debt, Fair Value Disclosure	60,780	57,244
Convertible Debt Par Value	55,636	55,636
Quoted Prices in Active Markets for Identical Assets (Level 1)
Derivative Assets	0	0
Derivative Liabilities	0	0
Rabbi Trust Asset Fair Value Disclosure	1,337	1,350
Financial Instruments Asset Liabilities at Fair Value Net	1,337	1,350
Significant Other Observable Inputs (Level 2)
Derivative Assets	520	1,617
Derivative Liabilities	(316)	(667)
Rabbi Trust Asset Fair Value Disclosure	0	0
Financial Instruments Asset Liabilities at Fair Value Net	204	950
Significant Unobservable Inputs (Level 3)
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]
Derivative Assets	520	1,617
Derivative Liabilities	(316)	(667)
Rabbi Trust Asset Fair Value Disclosure	1,337	1,350
Financial Instruments Asset Liabilities at Fair Value Net	$ 1,541	$ 2,300