Short-term Investments (Tables)

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Short-term Investments

The following table summarizes the amortized cost, gross unrealized gains and losses, and fair value of available-for-sale investments as of March 31, 2019:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Aggregate Fair Value
U.S. government debt securities	$	74,752	$	—	$	(14	)	$	74,738
Certificates of deposit	352		—		—			352
Total	$	75,104	$	—	$	(14	)	$	75,090

The following table summarizes the amortized cost, gross unrealized gains and losses, and fair value of available-for-sale investments as of December 31, 2018:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Aggregate Fair Value
U.S. government debt securities	$	119,401	$	—	$	(61	)	$	119,340
Certificates of deposit	348		—		—			348
Total	$	119,749	$	—	$	(61	)	$	119,688