Other Liabilities - Components of Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Liabilities Disclosure [Abstract]
Deferred tax liability	$ 12,592	$ 9,838
Unpaid claims liability	5,167	3,896	$ 3,908	$ 3,121
Other liabilities, Total	$ 81,026	$ 87,669