Investments (Tables)

9 Months Ended

Sep. 30, 2018

Investments Debt And Equity Securities [Abstract]

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

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

	September 30, 2018
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
Commercial Paper	$	1,397	$	—	$	—		$	1,397
Corporate Bonds		4,298		—		(2	)		4,296
Treasury Bonds		11,490		—		(6	)		11,484
	$	17,185	$	—		(8	)	$	17,177

	December 31, 2017
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
Commercial Paper	$	6,198	$	—	$	—		$	6,198
Certificates of Deposit		8,916		—		—			8,916
Corporate Bonds		58,937		—		(72	)		58,865
Government Securities		22,997		—		(43	)		22,954
Treasury Bonds		16,992		—		(30	)		16,962
	$	114,040	$	—	$	(145	)	$	113,895