Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Disclosures [Abstract]

Assets And Liabilities Measured At Fair Value On A Recurring Basis

	As of December 31, 2012		Quoted Prices In Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Assets:
Cash and cash equivalents:
Money market funds	$	123,519	$	123,519	$	—	$	—
Corporate securities	16,476		—		16,476		—
Cash	503,614		503,614		—		—
Available-for-sale securities:
Agency securities	402,707		—		402,707		—
Corporate securities	405,322		—		401,981		3,341
Municipal securities	32,313		—		32,313		—
Government securities	39,993		—		39,993		—
Prepaid expenses and other current assets:
Foreign currency derivatives	4,157		—		4,157		—
Total assets	$	1,528,101	$	627,133	$	897,627	$	3,341
Accrued expenses and other current liabilities:
Foreign currency derivatives	4,162		—		4,162		—
Total liabilities	$	4,162	$	—	$	4,162	$	—

Assets Measured At Fair Value On A Recurring Basis Using Significant Unobservable Inputs

	Investments
	(in thousands)
Balance at December 31, 2011	$	3,696
Purchases of Level 3 securities	7,605
Transfers out of Level 3	(5,460		)
Total realized losses included in earnings	(2,500		)
Balance at December 31, 2012	$	3,341