Cash equivalents and investments, all of which are classified as available-for-sale securities and restricted cash, consisted of the following (in thousands):

	March 31, 2019									December 31, 2018
	Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value		Cost			Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Money market funds	$	12,047	$	—	$	—		$	12,047		$	14,077	$	—	$	—		$	14,077
Corporate notes and commercial paper		63,817		8		(13	)		63,812			73,769		—		(36	)		73,733
U.S. treasury securities		22,392		18		—			22,410			20,334		4		(4	)		20,334
U.S. government agency securities		18,473		—		(20	)		18,453			28,149		—		(77	)		28,072
	$	116,729	$	26	$	(33	)	$	116,722		$	136,329	$	4	$	(117	)	$	136,216
Classified as:
Cash equivalents								$	39,867									$	50,681
Short-term investments									76,415										85,095
Restricted cash									440										440
Total cash equivalents, restricted cash and investments								$	116,722									$	136,216

At March 31, 2019, the remaining contractual maturities of available-for-sale securities were less than one year. There have been no significant realized gains or losses on available-for-sale securities for the periods presented. As of March 31, 2019, unrealized losses on cash equivalents and investments were $33,000 and the losses were deemed to be temporary. The gross unrealized loss that had been in a continuous loss position for 12 months or longer was $22,000 and $59,000 as of March 31, 2019, and December 31, 2018, respectively. The Company had unrealized losses of $22,000 on investments with an aggregate fair value of $20.5 million that were in a continuous loss position for 12 months or longer as of March 31, 2019. The Company does not intend to sell its securities that are in an unrealized loss position, and it is unlikely that the Company will be required to sell its securities before recovery of their amortized cost basis, which may be maturity. Factors considered in determining whether a loss is temporary include the length of time and extent to which the fair value has been less than the amortized cost basis and whether the Company intends to sell the security or whether it is more likely than not that the Company would be required to sell the security before recovery of the amortized cost basis. As of March 31, 2019, the Company had a total of $117.4 million in cash, cash equivalents, restricted cash and short-term investments, which includes $0.7 million in cash and $116.7 million in cash equivalents, restricted cash and investments.