Leases - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating Leased Assets [Line Items]
Operating lease assets	$ 16,222		$ 0
Operating lease liabilities	$ 17,109		$ 0
Accounting Standards Update 2016-02
Operating Leased Assets [Line Items]
Operating lease assets		$ 12,500
Prepaid rent		800
Operating lease liabilities		$ 13,300