Available-for-Sale Securities

12 Months Ended

Dec. 31, 2017

4. Available-for-Sale Securities

As of December 31, 2017, the Company held no available-for-sale securities. The following table summarizes the available-for-sale securities held at December 31, 2016 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
December 31, 2016
Corporate debt securities	$	13,934	$	—	$	(4	)	$	13,930
U.S. government-sponsored securities		1,001		—		—			1,001

Total	$	14,935	$	—	$	(4	)	$	14,931

The contractual maturities of all available-for-sale securities held at December 31, 2016 were one year or less. There were fifteen available-for-sale securities in an unrealized loss position at December 31, 2016, none of which had been in an unrealized loss position for more than 12 months. The aggregate fair value of these securities at December 31, 2016 was approximately $13.0 million. The Company did not hold any securities with other-than-temporary impairment at December 31, 2016.

Gross realized gains and losses on the sales of available-for-sale securities are included in other income, net. Unrealized holding gains or losses for the period that have been included in accumulated other comprehensive income, as well as gains and losses reclassified out of accumulated other comprehensive income into other income, net were not material to the Company's condensed consolidated results of operations. The cost of securities sold or the amount reclassified out of the accumulated other comprehensive income into other income, net is based on the specific identification method for purposes of recording realized gains and losses. During the year ended December 31, 2016 the Company received $7.8 million in proceeds from sales of available-for-sale securities. There were no proceeds from sales of available-for-sale securities in the year ended December 31, 2017, as all proceeds related to maturities of underlying securities. The gains on proceeds from sales and maturities of available-for-sale securities were not material to the Company's condensed consolidated results of operations for the years ended December 31, 2017 and 2016.