Deferred Acquisition Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Acquisition Costs [Line Items]
Beginning balance, net	$ (13,709)	$ (13,824)	$ (13,709)	$ (13,824)	$ (14,113)	$ (13,609)	$ (13,440)	$ (13,609)	$ (12,143)
Additions	7,011	7,180	14,698	14,769
Amortization	7,415	6,796	14,598	13,088
Balance at June 30, net	$ 13,709	$ 13,824	$ 13,709	$ 13,824