Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2015

Fair Value Disclosures [Abstract]

Fair Value, Assets Measured on Recurring Basis

The following tables present information about our assets that are measured at fair value on a recurring basis using the above input categories (in thousands):

	Level 1		Level 2		Total
March 31, 2015
Cash equivalents:
Money market mutual funds	$	13,199	$	—	$	13,199
Marketable securities:
U.S. agency obligations	—		153,203		153,203
U.S. treasury securities	—		5,527		5,527
	$	13,199	$	158,730	$	171,929

	Level 1		Level 2		Total
December 31, 2014
Cash equivalents:
Money market mutual funds	$	1,919	$	—	$	1,919
U.S. agency obligations	—		1,561		1,561
Marketable securities:
U.S. agency obligations	—		175,696		175,696
U.S. treasury securities	—		5,581		5,581
	$	1,919	$	182,838	$	184,757