Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating Loss Carryforwards [Line Items]
Proceeds from income tax refunds, net of taxes paid			$ 42,600,000
Payments for income taxes, net of tax refunds received	22,300,000	36,600,000
Proceeds from income tax refunds, gross			61,600,000
Refund received for the amended carryback claim		19,900,000
Valuation allowances		6,632,000
Unrecognized tax benefits	0
Deferred tax assets, tax credit carryforwards, foreign		174,054,000
Unrealized excess tax benefit from stock based compensation	12,200,000
Foreign Country [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets, tax credit carryforwards, foreign		174,100,000
Tunisia [Member]
Operating Loss Carryforwards [Line Items]
Payments for income taxes, net of tax refunds received	$ 12,200,000	$ 17,800,000	$ 10,600,000
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Income tax examination, year(s) under examination	The Internal Revenue Service recently closed the examination of the 2007, 2008 and 2009 tax years, and is concluding an examination of the 2010 tax year.