Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Schedule of Marketable Securities

The following is a summary of available-for-sale marketable securities held as of December 31, 2015 and 2014 (in thousands):

			Gross Unrealized					Aggregate Fair Value		Classification on Balance Sheet
	Amortized Cost									Short-Term Marketable Securities		Long-Term Marketable Securities
As of December 31, 2015			Gains		Losses
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
As of December 31, 2014
Certificates of deposit	$	39	$	—	$	—		$	39	$	—	$	39
Commercial paper	10,487		—		(2		)	10,485		10,485		—
Corporate bonds	1,077,387		454		(2,132		)	1,075,709		424,777		650,932
U.S. government agency obligations	303,808		20		(427		)	303,401		84,380		219,021
	$	1,391,721	$	474	$	(2,561	)	$	1,389,634	$	519,642	$	869,992

Schedule of Fair Value Measurement

The following table details the fair value measurements within the fair value hierarchy of the Company’s financial assets and liabilities as of December 31, 2015 and 2014 (in thousands):

	Total Fair Value			Fair Value Measurements at Reporting Date Using
				Level 1		Level 2		Level 3
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	$	—
As of December 31, 2014
Cash Equivalents and Marketable Securities:
Money market funds	$	501		$	501	$	—	$	—
Certificates of deposit	39			39		—		—
Commercial paper	10,485			—		10,485		—
Corporate bonds	1,075,709			—		1,075,709		—
U.S. government agency obligations	303,401			—		303,401		—
	$	1,390,135		$	540	$	1,389,595	$	—
Other Liabilities:
Contingent consideration obligation related to Velocius acquisition	$	(900	)	$	—	$	—	$	(900	)

Schedule of Activity of Major Classes of Assets Measured at Fair Value Using Level 3 Inputs

The following table reflects the activity for the Company’s major classes of assets and liabilities measured at fair value using Level 3 inputs for the years ended December 31, 2015 and 2014 (in thousands):

	Other Assets: Note Receivable			Other Liabilities: Contingent Consideration Obligation
Balance, January 1, 2014	$	22,879		$	(2,600	)
Fair value adjustment to Velocius contingent consideration included in general and administrative expense	—			(300		)
Achievement of first milestone related to Velocius contingent consideration	—			2,000
Unrealized gain on convertible note receivable included in other comprehensive income	2,121			—
Amendment of the convertible note receivable for preferred stock of the issuer and cash	(25,000		)	—
Balance, December 31, 2014	$	—		$	(900	)
Fair value adjustment to Velocius contingent consideration included in general and administrative expense	—			(100		)
Achievement of final milestone related to Velocius contingent consideration	—			1,000
Balance, December 31, 2015	$	—		$	—

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 December 31, 2015 and 2014 were as follows (in thousands):

	December 31, 2015		December 31, 2014
Due in 1 year or less	$	460,088	$	519,642
Due after 1 year through 5 years	773,260		869,992
	$	1,233,348	$	1,389,634