Summary of Significant Accounting Policies - Schedule of Changes to Obsolete and Excess Inventories Reserve (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Obsolete Inventory Reserve
Balance at beginning of year	$ 3,881	$ 3,639	$ 3,836
Net additions charged to earnings	2,195	1,295	1,017
Disposals	(1,945)	(1,053)	(1,214)
Balance at end of year	$ 4,131	$ 3,881	$ 3,639