Deferred Acquisition Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Deferred Acquisition Costs [Line Items]
Beginning balance, net	$ (6,662)	$ (6,054)	$ (6,662)	$ (6,054)	$ (6,428)	$ (6,325)	$ (5,867)	$ (5,827)
Additions	1,256	1,331	2,498	2,317
Amortization	1,022	1,144	2,161	2,090
Balance at June 30, net	$ 6,662	$ 6,054	$ 6,662	$ 6,054