Fair value measurements (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities 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, 2019
	Total		Level 1		Level 2
Assets
Cash and cash equivalents:
Cash	$	1,310	$	1,310	$	—
Money market funds	250,782		250,782		—
Total cash and cash equivalents	252,092		252,092		—
Short-term investments:
U.S. Treasury bills	18,946		18,946		—
Corporate debt securities	117,109		—		117,109
Commercial paper	89,386		—		89,386
U.S. Agency bonds	5,998		—		5,998
Other sovereign securities	1,996		—		1,996
Total short-term investments	233,435		18,946		214,489
Total	$	485,527	$	271,038	$	214,489

	December 31, 2018
	Total		Level 1		Level 2
Assets
Cash and cash equivalents:
Cash	$	3,731	$	3,731	$	—
Money market funds	28,963		28,963		—
Total cash and cash equivalents	32,694		32,694		—
Short-term investments:
U.S. Treasury bills	3,771		3,771		—
Corporate debt securities	111,916		—		111,916
Commercial paper	74,409		—		74,409
Total short-term investments	190,096		3,771		186,325
Total	$	222,790	$	36,465	$	186,325