Income Taxes - Components of Net Deferred Income Tax Asset and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Net deferred income tax asset - Non-current
Warranty cost	$ 310	$ 616
Inventory reserve	5,234	4,820
Unearned service revenue	11,607	11,616
Employee stock options	3,271	4,157
Tax credits	2,828	1,207
Loss carryforwards	8,530	7,481
Depreciation	1,419	345
Other, net	735	1,760
Intangibles & goodwill	19,295	0
Lease liability	6,986	4,591
Total deferred tax assets	60,215	36,593
Valuation allowance	(6,916)	(10,419)
Total deferred tax assets net of valuation allowance	53,299	26,174
Intangibles & goodwill	0	(3,174)
Right of use asset	(6,636)	(4,591)
Total deferred tax liabilities	(6,636)	(7,765)
Net deferred tax assets	$ 46,663	$ 18,409