Debt (Details) (USD $)			12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Senior Notes 6 Point 30 Percentage Member	Dec. 31, 2011 $870 Credit Agreement
Debt Instruments [Abstract]
$100 million Senior Notes, interest at 6.30%, due June 25, 2015	$ 100,000,000	$ 100,000,000
$870 million Credit Agreement, interest at LIBOR plus 105 basis points	376,715,000	556,481,000
Other Local Arrangements	28,300,000	24,722,000
Total Debt, Long-term and Short-term	505,015,000	681,203,000
Less: current portion	(28,300,000)	(10,902,000)
Long-term debt	476,715,000	670,301,000
Debt Instrument
Senior Notes, Face Amount			100,000,000
Senior Notes, Stated Interest Rate			6.30%
Maturity Date			Jun. 25, 2015	Dec. 20, 2016
Credit Agreement Borrowing Capacity				$ 870,000,000
$870 million Credit Agreement, Basis Spread on Variable Rate				1.05%