Other Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Assets, Noncurrent Disclosure [Abstract]
Demonstration assets, net	$ 1,982	$ 2,224
Deferred tax assets, net	3,114	1,807
Other	878	343
Other assets	$ 5,974	4,374
Useful life of demonstration assets	2 years
Amortization expense for demonstration assets	$ 1,800	$ 2,100	$ 1,800