Fair value measurements (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Schedule of assets and liabilities that are measured at fair value on a recurring basis

The following tables summarize the assets measured at fair value on a recurring basis (in thousands):

	June 30, 2018
	Total		Level 1		Level 2		Level 3
Assets
Cash and cash equivalents:
Cash	$	6,844	$	6,844	$	—	$	—
Money market funds	99,119		99,119		—		—
Total cash and cash equivalents	105,963		105,963		—		—
Short-term investments:
Corporate debt securities	88,921		—		88,921		—
Commercial paper	65,300		—		65,300		—
Total short-term investments	154,221		—		154,221		—
Total	$	260,184	$	105,963	$	154,221	$	—

	December 31, 2017
	Total		Level 1		Level 2		Level 3
Assets
Cash and cash equivalents:
Cash	$	1,026	$	1,026	$	—	$	—
Money market funds	106,677		106,677		—		—
Total cash and cash equivalents	107,703		107,703		—		—
Short-term investments:
Corporate debt securities	24,241		—		24,241		—
Commercial paper	18,893		—		18,893		—
Total short-term investments	43,134		—		43,134		—
Total	$	150,837	$	107,703	$	43,134	$	—