Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Dec. 31, 2011

Fair Value Disclosures [Abstract]

Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis

	Balance as of 2012		Quoted Prices  in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	852,979	$	690,691	$	162,288	$	—
Marketable securities	135,634		—		135,634		—
Derivatives	317		—		317		—
	$	988,930	$	690,691	$	298,239	$	—
Liabilities:
Derivatives	$	7,920	$	—	$	7,920	$	—

	Balance as  of 2011		Quoted Prices  in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	1,302,367	$	1,122,375	$	179,992	$	—
Marketable securities	153,380		—		153,380		—
Derivatives	16,443		—		16,443		—
	$	1,472,190	$	1,122,375	$	349,815	$	—
Liabilities:
Derivatives	$	5,136	$	—	$	5,136	$	—