Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Leases [Abstract]
Remaining term of operating leases (in years)	5 years
Minimum future operating lease payments [Abstract]
2018	$ 808
2019	823
2020	583
2021	48
2022 and thereafter	0
Total	2,262
Total rental expense under operating leases	$ 2,000	$ 2,100	$ 2,200