Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Cash and Cash Equivalents, Available-for-sale Securities Reconciliation

The Company's cash and cash equivalents, short-term investments, and long-term investments consist of the following:

	March 31, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	78,685	$	—	$	—		$	78,685
Money market funds	208		—		—			208
Commercial paper	14,284		—		(3		)	14,281
Total	93,177		—		(3		)	93,174
Short-term investments:
Commercial paper	11,866		—		(7		)	11,859
Corporate bonds	39,296		1		(139		)	39,158
U.S. government agencies	184,613		—		(277		)	184,336
Total	235,775		1		(423		)	235,353
Long-term investments:
Asset-backed securities	14,665		—		(32		)	14,633
U.S. government agencies	19,091		2		(73		)	19,020
Corporate bonds	32,097		1		(388		)	31,710
Total	65,853		3		(493		)	65,363
Total	$	394,805	$	4	$	(919	)	$	393,890

	December 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Cash and cash equivalents:
Cash	$	86,500	$	—	$	—		$	86,500
Money market funds	91		—		—			91
Total	86,591		—		—			86,591
Short-term investments:
Commercial paper	12,623		—		(3		)	12,620
Corporate bonds	38,425		1		(64		)	38,362
U.S. government agencies	151,058		—		(217		)	150,841
Total	202,106		1		(284		)	201,823
Long-term investments:
Asset-backed securities	4,998		—		(12		)	4,986
U.S. government agencies	24,269		—		(54		)	24,215
Corporate bonds	38,198		—		(175		)	38,023
Total	67,465		—		(241		)	67,224
Total	$	356,162	$	1	$	(525	)	$	355,638

Schedule of changes to accumulated other comprehensive income

The following table shows the changes to accumulated other comprehensive loss for the three months ended March 31, 2018 (in thousands):

	Unrealized (Loss) Gain, net on Investments
Balance at December 31, 2017	$	(574	)
Change in net unrealized loss on investments, net of tax	(407		)
Amounts reclassified for net realized gain included in net income, net of tax	16
Other comprehensive loss, net of tax	(391		)
Balance at March 31, 2018	$	(965	)

Schedule of Assets Measured on Recurring Basis

The following table sets forth by level within the fair value hierarchy the fair value of the Company's available-for-sale securities measured on a recurring basis, excluding cash and money market funds:

	March 31, 2018
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	26,140	$	—	$	26,140
U.S. government agencies	—		203,356		—		203,356
Corporate bonds	—		70,868		—		70,868
Asset-backed securities	—		14,633		—		14,633
Total	$	—	$	314,997	$	—	$	314,997

	December 31, 2017
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Commercial paper	$	—	$	12,620	$	—	$	12,620
U.S. government agencies	—		175,056		—		175,056
Corporate bonds	—		76,385		—		76,385
Asset-backed securities	—		4,986		—		4,986
Total	$	—	$	269,047	$	—	$	269,047

Schedule of Available-for-Sale Securities by Contractual Maturity

The following summarizes the fair value of securities classified as available-for-sale by contractual, or effective, maturity:

	March 31, 2018
	Mature within One Year		After One Year through Two Years		Over Two Years		Fair Value
	(in thousands)
Commercial paper	$	26,140	$	—	$	—	$	26,140
U.S. government agencies	184,336		16,859		2,161		203,356
Corporate bonds	39,158		26,833		4,877		70,868
Asset-backed securities	6,162		8,471		—		14,633
Total	$	255,796	$	52,163	$	7,038	$	314,997

Summary of Gains (Losses) Recognized From Forward Contracts and Other Foreign Currency Transactions

The following summarizes the gains (losses) recognized in Other income (expense), net on the condensed consolidated statement of operations, from forward contracts and other foreign currency transactions:

	Three Months Ended
	March 31,
	2018			2017
	(in thousands)
Net loss from forward contracts	$	(578	)	$	(257	)
Other foreign currency transactions gain	810			260
Total foreign exchange gain, net	$	232		$	3