Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Commitments and Contingencies
Rent expense	$ 1,600	$ 1,300	$ 3,100	$ 2,500
Non-cancelable commitments under operating leases
2017 (remainder of year)	2,621		2,621
2018	5,965		5,965
2019	6,752		6,752
2020	7,082		7,082
2021	4,825		4,825
2022 and thereafter	5,117		5,117
Total minimum payments	$ 32,362		$ 32,362