Available-for-Sale Securities (Tables)

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of Fair Value of Available-for-Sale Securities by Type of Security

As of June 30, 2018 and December 31, 2017, the fair value of available-for-sale securities by type of security was as follows:

	June 30, 2018
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
U.S. government agency securities	$	9,286	$	—	$	(4	)	$	9,282
Corporate bond securities		7,659		—		(6	)		7,653
	$	16,945	$	—	$	(10	)	$	16,935

	December 31, 2017
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
U.S. government agency securities	$	9,473	$	—	$	(7	)	$	9,466
Corporate bond securities		7,554		—		(6	)		7,548
	$	17,027	$	—	$	(13	)	$	17,014

Summary Estimated Fair Value and Amortized Cost of Available-for-Sale Securities by Contractual Maturity

The estimated fair value and amortized cost of the Company’s available-for-sale securities by contractual maturity are summarized as follows:

	June 30, 2018				December 31, 2017
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due in one year or less	$	16,945	$	16,935	$	17,027	$	17,014
Total available-for-sale securities	$	16,945	$	16,935	$	17,027	$	17,014