Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) ft²	Jan. 01, 2019 USD ($)
Leases
Lessor, Operating Lease, Existence of Option to Extend [true false]	true
Lessor, Operating Lease, Existence of Option to Terminate [true false]	true
Lease to eliminate | ft²	16,200
lease to extend | ft²	33,400
lease to additional term	5 years
lease to termination term	3 years
Lease liabilities	$ 5,232
Right-of-use assets	$ 4,445
Lease term related to amendment	3 years
Operating lease expense	$ 700
Variable lease expense	400
Operating lease payments	$ 900
Weighted-average remaining lease term	2 years
Weighted-average discount rate	11.30%
ASC 842
Leases
Lease liabilities	$ 1,400	$ 4,700
Right-of-use assets	$ 1,400	$ 3,800