Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Schedule of Marketable Securities

The following is a summary of available-for-sale marketable securities held as of June 30, 2018 and December 31, 2017 (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 June 30, 2018
Certificates of deposit	$	75,000	$	—	$	(8	)	$	74,992	$	74,992	$	—
Commercial paper	284,414		—		(125		)	284,289		284,289		—
Corporate bonds	870,509		2		(7,164		)	863,347		501,251		362,096
U.S. government agency obligations	58,634		—		(635		)	57,999		18,841		39,158
	$	1,288,557	$	2	$	(7,932	)	$	1,280,627	$	879,373	$	401,254
As of December 31, 2017
Commercial paper	$	6,951	$	—	$	(9	)	$	6,942	$	6,942	$	—
Corporate bonds	736,902		2		(3,829		)	733,075		289,378		443,697
U.S. government agency obligations	220,014		—		(1,764		)	218,250		102,234		116,016
	$	963,867	$	2	$	(5,602	)	$	958,267	$	398,554	$	559,713

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 June 30, 2018 and December 31, 2017 (in thousands):

	Total Fair Value			Fair Value Measurements at Reporting Date Using
				Level 1		Level 2		Level 3
As of June 30, 2018
Cash Equivalents and Marketable Securities:
Money market funds	$	254,736		$	254,736	$	—	$	—
Certificates of deposit	74,992			74,992		—		—
Commercial paper	284,289			—		284,289		—
Corporate bonds	863,347			—		863,347		—
U.S. government agency obligations	57,999			—		57,999		—
Mutual funds	10,602			10,602		—		—
	$	1,545,965		$	340,330	$	1,205,635	$	—
Liabilities:
Contingent consideration related to a completed acquisition	$	(6,100	)	$	—	$	—	$	(6,100	)
As of December 31, 2017
Cash Equivalents and Marketable Securities:
Money market funds	$	22,649		$	22,649	$	—	$	—
Commercial paper	10,928			—		10,928		—
Corporate bonds	733,075			—		733,075		—
U.S. government agency obligations	218,248			—		218,248		—
Mutual funds	7,879			7,879		—		—
	$	992,779		$	30,528	$	962,251	$	—
Liabilities:
Contingent consideration related to a completed acquisition	$	(8,631	)	$	—	$	—	$	(8,631	)

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 June 30, 2018 and December 31, 2017 were as follows (in thousands):

	June 30, 2018		December 31, 2017
Due in 1 year or less	$	879,373	$	398,554
Due after 1 year through 3 years	401,254		559,713
	$	1,280,627	$	958,267

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 liabilities measured at fair value using Level 3 inputs during the six months ended June 30, 2018 (in thousands):

	Other Liabilities: Contingent Consideration Obligation
Balance as of January 1, 2018	$	(8,631	)
Fair value adjustment to contingent consideration included in general and administrative expense	(1,635		)
Cash paid upon achievement of milestone	4,166
Balance as of June 30, 2018	$	(6,100	)