Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2014

Fair Value Disclosures [Abstract]

Assets And Liabilities Measured At Fair Value On A Recurring Basis

Assets and Liabilities Measured at Fair Value on a Recurring Basis

	As of March 31, 2014		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:
Cash	$	290,579	$	290,579	$	—	$	—
Money market funds	5,942		5,942		—		—
Corporate securities	1,998		—		1,998		—
Available-for-sale securities:
Agency securities	638,334		—		638,334		—
Corporate securities	701,826		—		691,435		10,391
Municipal securities	57,122		—		57,122		—
Government securities	132,307		—		132,307		—
Prepaid expenses and other current assets:
Foreign currency derivatives	4,155		—		4,155		—
Total assets	$	1,832,263	$	296,521	$	1,525,351	$	10,391
Accrued expenses and other current liabilities:
Foreign currency derivatives	1,582		—		1,582		—
Total liabilities	$	1,582	$	—	$	1,582	$	—

	As of December 31, 2013		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:
Cash	$	227,528	$	227,528	$	—	$	—
Money market funds	52,823		52,823		—		—
Corporate securities	389		—		389		—
Available-for-sale securities:
Agency securities	454,750		—		454,750		—
Corporate securities	644,091		—		633,801		10,291
Municipal securities	53,756		—		53,756		—
Government securities	157,079		—		157,079		—
Prepaid expenses and other current assets:
Foreign currency derivatives	4,952		—		4,952		—
Total assets	$	1,595,368	$	280,351	$	1,304,727	$	10,291
Accrued expenses and other current liabilities:
Foreign currency derivatives	1,743		—		1,743		—
Total liabilities	$	1,743	$	—	$	1,743	$	—

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

	Corporate Securities
	(in thousands)
Balance at December 31, 2013	$	10,291
Purchases of Level 3 securities	100
Balance at March 31, 2014	$	10,391