Commitments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Commitments
Rental expense	$ 200	$ 200
Future minimum payments for operating leases
Remainder of 2017	396
2018	456
2019	449
2020	358
2021 and thereafter	997
Total	2,656
Future minimum payments for other commitments
Remainder of 2017	4,216
2018	3,482
2019	1,635
2020	622
2021 and thereafter	10
Total	9,965
Future minimum payments for operating leases and other commitments
Remainder of 2017	4,612
2018	3,938
2019	2,084
2020	980
2021 and thereafter	1,007
Total	$ 12,621