Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of Marketable Securities

The following is a summary of available-for-sale marketable securities held as of March 31, 2016 and December 31, 2015 (in thousands):

			Gross Unrealized							Classification on Balance Sheet
	Amortized Cost		Gains		Losses			Aggregate Fair Value		Short-Term Marketable Securities		Long-Term Marketable Securities
As of March 31, 2016
Commercial paper	$	2,495	$	—	$	(1	)	$	2,494	$	2,494	$	—
Corporate bonds	962,932		1,203		(506		)	963,629		479,400		484,229
U.S. government agency obligations	241,315		289		(26		)	241,578		43,064		198,514
	$	1,206,742	$	1,492	$	(533	)	$	1,207,701	$	524,958	$	682,743
As of December 31, 2015
Commercial paper	$	2,491	$	—	$	(4	)	$	2,487	$	2,487	$	—
Corporate bonds	995,100		73		(3,365		)	991,808		432,585		559,223
U.S. government agency obligations	239,587		41		(575		)	239,053		25,016		214,037
	$	1,237,178	$	114	$	(3,944	)	$	1,233,348	$	460,088	$	773,260

Schedule of Fair Value Measurement

The following table details the fair value measurements within the fair value hierarchy of the Company’s financial assets at March 31, 2016 and December 31, 2015 (in thousands):

	Total Fair Value		Fair Value Measurements at Reporting Date Using
			Level 1		Level 2		Level 3
As of March 31, 2016
Cash Equivalents and Marketable Securities:
Money market funds	$	22,035	$	22,035	$	—	$	—
Commercial paper	2,494		—		2,494		—
Corporate bonds	963,629		—		963,629		—
U.S. government agency obligations	241,578		—		241,578		—
Mutual funds	2,619		2,619		—		—
	$	1,232,355	$	24,654	$	1,207,701	$	—
As of December 31, 2015
Cash Equivalents and Marketable Securities:
Money market funds	$	1,250	$	1,250	$	—	$	—
Commercial paper	2,487		—		2,487		—
Corporate bonds	991,808		—		991,808		—
U.S. government agency obligations	239,053		—		239,053		—
Mutual funds	1,414		1,414		—		—
	$	1,236,012	$	2,664	$	1,233,348	$	—

Schedule of Contractual Maturities of Marketable Securities and Other Investment Related Assets

Contractual maturities of the Company’s available-for-sale marketable securities held as of March 31, 2016 and December 31, 2015 were as follows (in thousands):

	March 31, 2016		December 31, 2015
Due in 1 year or less	$	524,958	$	460,088
Due after 1 year through 5 years	682,743		773,260
	$	1,207,701	$	1,233,348