Summary of Significant Accounting Policies - Warranty Reserves (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in the warranty reserve
Accrued warranty reserve, beginning of period	$ 3,581	$ 1,767	$ 3,333	$ 1,528
Reserve provided	952	1,818	2,440	2,954
Payments	(1,004)	(1,168)	(2,244)	(2,065)
Accrued warranty reserve, end of period	$ 3,529	$ 2,417	$ 3,529	$ 2,417