Intangible Assets - Assets subject to amortization (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 3,458	$ 3,458
Less accumulated amortization	593	474
Intangible assets subject to amortization, net	2,865	2,984
Trade names
Finite-Lived Intangible Assets [Line Items]
Intangible assets	3,410	3,410
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 48	$ 48