Leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 200
Finance lease expense	100
Short term lease costs	2,100
Cash paid for operating leases	200
Cash paid for finance leases	114	$ 0
Right-of-use assets obtained in exchange for lease obligations	$ 600
Operating lease, weighted average lease term	1 year 10 months 24 days
Finance lease, weighted average lease term	1 year 9 months 18 days
Operating lease, weighted average discount rate (as a percent)	4.35%
Finance lease, weighted average discount rate (as a percent)	6.57%
Minimum
Lessee, Lease, Description [Line Items]
Renewal term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Renewal term	3 years