Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2018

Schedule of available-for-sale securities


	June 30, 2018								December 31, 2017
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value		Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
	(in thousands)
Money market deposits	$	569	$	—	$	—	$	569	$	3,477	$	—	$	—	$	3,477
U.S. Treasury securities		37,445		—		(580)		36,865		67,480		10		(464)		67,026
U.S. agency securities		22,544		—		(212)		22,332		27,293		—		(221)		27,072
Municipal securities		11,770		—		(66)		11,704		12,240		—		(91)		12,149
Total	$	72,328	$	—	$	(858)	$	71,470	$	110,490	$	10	$	(776)	$	109,724

Classified as:
Cash equivalents							$	569							$	3,477
Short-term investments								70,901								106,247
Total							$	71,470							$	109,724

Summarized portfolio of available-for-sale securities by contractual maturity


	June 30, 2018
	Amortized Cost		Fair Value
	(in thousands)
Less than one year	$	33,114	$	32,989
Greater than one year but less than five years		38,645		37,912
Total	$	71,759	$	70,901

- 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