Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2013

Fair Value Disclosures [Abstract]

Schedule of assets measured at fair value on a recurring basis

The Company’s assets that are measured at fair value on a recurring basis, at December 31, 2013 and 2012, consist of the following:

			Fair Value Measurements at Reporting Date Using
At December 31, 2013	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Unrestricted
Available-for-sale marketable securities:
U.S. government and government agency obligations	$	107,521	—		$	107,521
Corporate bonds	369,193		—		369,193
Commercial paper	23,944		—		23,944
Municipal bonds	36,921		—		36,921
International government agency obligations	2,008		—		2,008
Certificates of deposit	7,514		—		7,514
Equity securities	1,166		$	1,166	—
	$	548,267	$	1,166	$	547,101
At December 31, 2012
Unrestricted
Available-for-sale marketable securities:
U.S. government and government agency obligations	$	328,146	—		$	328,146
Municipal bonds	17,510		—		17,510
Equity securities	3,393		$	3,393	—
	349,049		3,393		345,656
Restricted
Available-for-sale marketable securities:
U.S. government obligations	5,909		—		5,909
	$	354,958	$	3,393	$	351,565