Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2013
Income Tax Examination [Line Items]
Liability for uncertain tax positions	$ 123,085
Expected decrease in liabilities for unrecognized tax benefits	68,000
Recognition of an income tax benefit	24,000
Reversal of deferred tax assets	16,000
Expected increase in accrued income taxes	28,000
Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Years Under Examination	2008 and 2009
Mexican Tax Authorities [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Years Under Examination	2000 to 2007
Tax assessments relating to Mexican tax examinations for the years 2000 to 2007	245,130
Bonds provided to the Mexican government related to the 2000 to 2004 assessments	$ 184,990