Cash Equivalents and Investments

3 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Cash Equivalents and Investments

3. Cash Equivalents and Investments

The amortized cost and fair value of cash equivalents and investments at March 31, 2018 and December 31, 2017 were as follows (in thousands):

	March 31, 2018
	Amortized		Gross Unrealized					Fair
	Cost		Gains		Losses			Value
Money market fund	$	17,963	$	—	$	—		$	17,963
U.S. treasury securities		34,986		—		(53	)		34,933
Commercial paper		51,923		—		—			51,923
Corporate debt securities		68,895		—		(250	)		68,645
Total available-for-sale securities	$	173,767	$	—	$	(303	)	$	173,464
Classified as:
Cash equivalents								$	26,938
Short-term investments									116,018
Long-term investments									30,508
Total available-for-sale securities								$	173,464

	December 31, 2017
	Amortized		Gross Unrealized					Fair
	Cost		Gains		Losses			Value
Money market fund	$	29,848	$	—	$	—		$	29,848
U.S. treasury securities		29,005		—		(52	)		28,953
Commercial paper		46,184		—		—			46,184
Corporate debt securities		27,095		—		(67	)		27,028
Total available-for-sale securities	$	132,132	$	—	$	(119	)	$	132,013
Classified as:
Cash equivalents								$	36,813
Short-term investments									87,271
Long-term investments									7,929
Total available-for-sale securities								$	132,013

Cash equivalents in the tables above exclude cash of $3.6 million and $3.2 million as of March 31, 2018 and December 31, 2017, respectively. All available-for-sale securities held as of March 31, 2018 had contractual maturities of less than two years. There have been no significant realized gains or losses on available-for-sale securities for the periods presented. No significant available-for-sale securities held as of March 31, 2018 have been in a continuous unrealized loss position for more than 12 months. As of March 31, 2018, unrealized losses on available-for-sale investments are not attributed to credit risk and are considered to be temporary. The Company believes that it is more-likely-than-not that investments in an unrealized loss position will be held until maturity or the recovery of the cost basis of the investment. The Company believes it has no other-than-temporary impairments on its securities because it does not intend to sell these securities and it believes it is not more likely than not that it will be required to sell these securities before the recovery of their amortized cost basis. To date, the Company has not recorded any impairment charges on marketable securities related to other-than-temporary declines in market value.