Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of Marketable Securities

The following is a summary of available-for-sale marketable securities held as of September 30, 2019 and December 31, 2018 (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 September 30, 2019
Commercial paper	$	78,454	$	20	$	(38	)	$	78,436	$	78,436	$	—
Corporate bonds	1,286,133		1,491		(878		)	1,286,746		638,604		648,142
U.S. government agency obligations	186,836		16		(196		)	186,656		114,468		72,188
	$	1,551,423	$	1,527	$	(1,112	)	$	1,551,838	$	831,508	$	720,330
As of December 31, 2018
Certificates of deposit	$	40,000	$	—	$	(7	)	$	39,993	$	39,993	$	—
Commercial paper	282,996		—		(50		)	282,946		282,946		—
Corporate bonds	685,653		1		(4,309		)	681,345		482,088		199,257
U.S. government agency obligations	50,876		—		(404		)	50,472		50,472		—
	$	1,059,525	$	1	$	(4,770	)	$	1,054,756	$	855,499	$	199,257

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 September 30, 2019 and December 31, 2018 (in thousands):

	Total Fair Value			Fair Value Measurements at Reporting Date Using
				Level 1		Level 2		Level 3
As of September 30, 2019
Cash Equivalents and Marketable Securities:
Money market funds	$	4,000		$	4,000	$	—	$	—
Commercial paper	78,436			—		78,436		—
Corporate bonds	1,286,746			—		1,286,746		—
U.S. government agency obligations	186,656			—		186,656		—
Mutual funds	14,027			14,027		—		—
	$	1,569,865		$	18,027	$	1,551,838	$	—
As of December 31, 2018
Cash Equivalents and Marketable Securities:
Money market funds	$	380,260		$	380,260	$	—	$	—
Certificates of deposit	39,993			39,993		—		—
Commercial paper	282,946			—		282,946		—
Corporate bonds	681,345			—		681,345		—
U.S. government agency obligations	50,472			—		50,472		—
Mutual funds	10,016			10,016		—		—
	$	1,445,032		$	430,269	$	1,014,763	$	—
Liabilities:
Contingent consideration related to a completed acquisition	$	(6,300	)	$	—	$	—	$	(6,300	)

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 September 30, 2019 and December 31, 2018 were as follows (in thousands):

	September 30, 2019		December 31, 2018
Due in 1 year or less	$	831,508	$	855,499
Due after 1 year through 3 years	720,330		199,257
	$	1,551,838	$	1,054,756

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 liabilities measured at fair value using Level 3 inputs during the nine months ended September 30, 2019 (in thousands):

	Other Liabilities: Contingent Consideration Obligation
Balance as of January 1, 2019	$	(6,300	)
Cash paid upon achievement of milestone	6,300
Balance as of September 30, 2019	$	—