Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

Summary of Fair Value Measurements of Cash Equivalents, Available-for-Sale Securities and Contingent Consideration Liability

The fair value measurements of our cash equivalents, available-for-sale marketable securities and contingent consideration liability are identified at the following levels within the fair value hierarchy (in thousands):

	September 30, 2014
	Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	7,193	$	7,193	$	—	$	—
Total		7,193		7,193		—		—
Marketable securities:
Commercial paper securities		36,247		—		36,247		—
Corporate debt securities		20,611		—		20,611		—
U.S. government sponsored entity debt    securities		163,410		—		163,410		—
Total		220,268		—		220,268		—
Total cash equivalents and marketable securities	$	227,461	$	7,193	$	220,268	$	—
Liabilities:
Contingent consideration liability	$	1,700	$	—	$	—	$	1,700
Total	$	1,700	$	—	$	—	$	1,700

	December 31, 2013
	Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	6,934	$	6,934	$	—	$	—
Total		6,934		6,934		—		—
Marketable securities:
U.S. government sponsored entity debt    securities		121,290		—		121,290		—
Total cash equivalents and marketable securities	$	128,224	$	6,934	$	121,290	$	-
Liabilities:
Contingent consideration liability	$	1,570	$	—	$	—	$	1,570
Total	$	1,570	$	—	$	—	$	1,570

Schedule of Changes in Estimated Fair Value of Contingent Consideration Liability

The following sets forth the changes in the estimated fair value for our contingent consideration liability classified as Level 3 (in thousands):

Fair value as of December 31, 2013	$	1,570
Change in fair value		130
Fair value as of September 30, 2014	$	1,700