Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 4,103		$ 0
Operating lease liabilities	4,125
Adjustment due to adoption of ASC 842, Leases		$ 823
Finance lease assets	5,220
Finance lease liabilities	$ 5,453
Accumulated Deficit
Lessee, Lease, Description [Line Items]
Adjustment due to adoption of ASC 842, Leases		823
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease assets		4,900
Operating lease liabilities		4,900
Finance lease assets		1,800
Finance lease liabilities		1,800
Accounting Standards Update 2016-02 | Accumulated Deficit
Lessee, Lease, Description [Line Items]
Adjustment due to adoption of ASC 842, Leases		$ 800