Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Income Tax Examination [Line Items]
Liability for uncertain tax positions	$ 108,228
Net tax payments expected in the next twelve months	5,900
Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Tax years under examination	2008 and 2009
Mexican Tax Authorities [Member]
Income Tax Examination [Line Items]
Tax years under examination	2000 to 2005
Tax assessments relating to Mexican tax examinations for the years 2000 to 2005	195,760
Bonds provided to the Mexican government related to the 2000 to 2004 assessments	$ 165,960