Cash Equivalents and Short-Term Investments

12 Months Ended

Dec. 31, 2016

Cash Cash Equivalents And Short Term Investments [Abstract]

Cash Equivalents and Short-Term Investments

Note 3. Cash Equivalents and Short-Term Investments

The fair value and amortized cost of cash equivalents and short-term investments by major security type as of December 31, 2016 and 2015 are presented in the tables that follow:

	December 31, 2016
	Amortized Cost		Unrealized Gains		Unrealized Losses			Market Value
	(in thousands)
Money market funds	$	26,439	$	—	$	—		$	26,439
Commercial paper		29,428		—		—			29,428
Corporate securities		19,601		—		(23	)		19,578
Agency discount instruments		2,997		1		—			2,998
U.S. government agency securities		22,021		—		(6	)		22,015
Total cash equivalents and available-for-sale    securities	$	100,486	$	1	$	(29	)	$	100,458

	December 31, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Market Value
	(in thousands)
Money market funds	$	19,787	$	—	$	—		$	19,787
Commercial paper		3,996		—		—			3,996
Corporate securities		16,548		—		(8	)		16,540
U.S. government agency securities		4,016		—		(2	)		4,014
Total cash equivalents and available-for-sale securities	$	44,347	$	—	$	(10	)	$	44,337

Realized gains and losses on the sale of marketable securities during the years ended December 31, 2016 and 2015 were not material.

For securities in a loss position, the following table shows the investments’ gross unrealized loss and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2016 and 2015:

	December 31, 2016
	Less than 12 Months					More than 12 Months				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
	(in thousands)
Corporate securities	$	19,578	$	(23	)	$	—	$	—	$	19,578	$	(23	)
U.S. government agency    securities		22,015		(6	)		—		—		22,015		(6	)
Total cash equivalents and    available-for-sale securities	$	41,593	$	(29	)	$	—	$	—	$	41,593	$	(29	)

	December 31, 2015
	Less than 12 Months					More than 12 Months				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
	(in thousands)
Corporate securities	$	16,539	$	(8	)	$	—	$	—	$	16,539	$	(8	)
U.S. government agency    securities		4,014		(2	)		—		—		4,014		(2	)
Total cash equivalents and    available-for-sale securities	$	20,553	$	(10	)	$	—	$	—	$	20,553	$	(10	)