Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Change in unrecognized tax benefits
Balance as of January 1	$ 68,848,000	$ 81,174,000	$ 69,048,000
Additions based on tax positions related to the current year	922,000	1,850,000	1,026,000
Additions for tax positions of prior years	16,372,000	11,748,000	17,060,000
Reductions for tax positions of prior years	(1,174,000)	(11,082,000)	(4,709,000)
Settlements	(1,018,000)	(14,842,000)	(1,251,000)
Balance as of December 31	83,950,000	68,848,000	81,174,000
Interest and penalties on unrecognized tax benefits	42,800,000	28,200,000	42,900,000
Liability related to unrecognized tax benefit for accrued interest and penalties	2,700,000	4,600,000	5,100,000
Algeria Audit Assessment
Change in unrecognized tax benefits
Addition to unrecognized tax benefits	$ 10,400,000