Income Taxes - Components of Net Deferred Income Tax Asset and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Net deferred income tax asset - Non-current
Warranty cost	$ 616	$ 533
Inventory reserve	4,820	1,559
Unearned service revenue	11,616	6,684
Employee stock options	4,157	4,222
Tax credits	1,207	485
Loss carryforwards	7,481	7,038
Depreciation	345	0
Other, net	1,760	641
Total deferred tax assets	32,002	21,162
Valuation allowance	(10,419)	(1,924)
Total deferred tax assets net of valuation allowance	21,583	19,238
Depreciation	0	(2,996)
Intangibles & goodwill	(3,174)	(2,261)
Total deferred tax liabilities	(3,174)	(5,257)
Net deferred tax assets	$ 18,409	$ 13,981