Investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments Debt And Equity Securities [Abstract]

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

As of December 31, 2017 and 2016, the fair value of available-for-sale investments by type of security was as follows:

	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

	December 31, 2016
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
Commercial Paper	$	19,631	$	58	$	—		$	19,689
Certificates of Deposit		10,629		—		—			10,629
Corporate Bonds		94,764		—		(155	)		94,609
Government Securities		33,513		—		(47	)		33,466
Treasury Bonds		17,066		1		(4	)		17,063
	$	175,603	$	59	$	(206	)	$	175,456

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details