Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Summary of Available-for-sale Short-Term Investments

The following table summarizes our available-for-sale short-term investments (in thousands):

	Aggregate Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
December 31, 2014
Money market mutual funds	$	666	$	—	$	—		$	666
Fixed income securities:
Certificates of deposit	29,233		—		(23		)	29,210
Commercial paper	10,187		7		(2		)	10,192
Corporate notes and bonds	12,076		—		(29		)	12,047
Government agencies	16,681		4		(17		)	16,668
U.S. Treasuries	2,151		—		(4		)	2,147
Variable rate demand obligations	4,213		—		—			4,213
Total available-for-sale investments	$	75,207	$	11	$	(75	)	$	75,143
December 31, 2015
Money market mutual funds	$	1	$	—	$	—		$	1
Fixed income securities:
Certificates of deposit	10,535		—		(3		)	10,532
Commercial paper	5,689		19		—			5,708
Corporate notes and bonds	2,006		—		—			2,006
Government agencies	3,598		4		—			3,602
Total available-for-sale investments	$	21,829	$	23	$	(3	)	$	21,849