Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Schedule of available-for-sale securities


	December 31, 2017								December 31, 2016
	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	$	3,477	$	—	$	—	$	3,477	$	10,777	$	—	$	—	$	10,777
U.S. Treasury securities		67,480		10		(464)		67,026		57,846		—		(404)		57,442
U.S. agency securities		27,293		—		(221)		27,072		56,261		—		(147)		56,114
Municipal securities		12,240		—		(91)		12,149		17,478		—		(174)		17,304
Total	$	110,490	$	10	$	(776)	$	109,724	$	142,362	$	—	$	(725)	$	141,637

Classified as:
Cash equivalents							$	3,477							$	10,777
Short-term investments								106,247								130,860
Total							$	109,724							$	141,637

Change in net unrealized positions of available-for-sale securities and reclassifications from AOCL upon sale


	December 31,
	2017		2016
	(in thousands)
Balance at beginning of year	$	(725)	$	(1,416)
Net unrealized (losses) gains on available-for-sale securities, net of tax		(105)		882
Reclassifications of losses (gains) realized from sale of available-for-sale securities		64		(191)
(Decrease) increase in other comprehensive loss		(41)		691
Balance at end of year	$	(766)	$	(725)

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


	December 31, 2017
	Amortized Cost		Fair Value
	(in thousands)
Less than one year	$	57,168	$	57,046
Greater than one year but less than five years		49,845		49,201
Total	$	107,013	$	106,247

- 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.

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- Definition

Tabular disclosure of the realized and unrealized gains and losses reported in the statement of income which have resulted from the sale and holding of marketable securities, respectively, as well as the sale or disposal of cost method investments. Such amounts would include realized gains and losses on the sale or disposal of trading, available-for-sale, and held-to-maturity securities, unrealized gains and losses on trading securities, unrealized gains and losses on available-for-sale and held-to-maturity securities transferred to the trading securities category, realized gains and losses on the sale or disposal of cost method investments, and losses recognized for other than temporary impairments (OTTI) of such investments.

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