Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Marketable Securities

The following is a summary of available-for-sale marketable securities held as of March 31, 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 March 31, 2018
Commercial paper	$	5,707	$	—	$	(17	)	$	5,690	$	5,690	$	—
Corporate bonds	734,080		—		(7,253		)	726,827		301,960		424,867
U.S. government agency obligations	219,515		—		(1,887		)	217,628		140,145		77,483
	$	959,302	$	—	$	(9,157	)	$	950,145	$	447,795	$	502,350
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 March 31, 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 March 31, 2018
Cash Equivalents and Marketable Securities:
Money market funds	$	7,059		$	7,059	$	—	$	—
Commercial paper	5,690			—		5,690		—
Corporate bonds	726,827			—		726,827		—
U.S. government agency obligations	217,628			—		217,628		—
Mutual funds	9,975			9,975		—		—
	$	967,179		$	17,034	$	950,145	$	—
Liabilities:
Contingent consideration related to a completed acquisition	$	(5,600	)	$	—	$	—	$	(5,600	)
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 March 31, 2018 and December 31, 2017 were as follows (in thousands):

	March 31, 2018		December 31, 2017
Due in 1 year or less	$	447,795	$	398,554
Due after 1 year through 3 years	502,350		559,713
	$	950,145	$	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 three months ended March 31, 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	(1,135		)
Cash paid upon achievement of milestone	4,166
Balance as of March 31, 2018	$	(5,600	)