Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2015

Fair Value Measurements [Abstract]

Fair Value Hierarchy

The following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis (in thousands):

	Fair Value at March 31, 2015						Fair Value at December 31, 2014
Assets	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
Money market funds	$	156,158	$	—	$	—	$	20,354	$	—	$	—
U.S. agency debt securities		—		35,721		—		—		—		—
Government-backed security		—		18,000		—		—		7,500		—
Asset-backed securities		—		46,639		—		—		46,624		—
Corporate debt securities		—		66,046		—		—		89,097		—
Total cash equivalents and marketable securities	$	156,158	$	166,406	$	—	$	20,354	$	143,221	$	—