Supplementary Balance Sheet Information - Intangible Assets, Excluding Goodwill (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization, Net Carrying Value	$ 12,746
Intangible assets, Cost	18,500	$ 18,448
Intangible assets, Accumulated Amortization	(5,679)	(5,188)
Intangible assets, Net Carrying Value	12,821	13,260
Trademarks
Finite Lived Intangible Assets [Line Items]
Intangible assets not subject to amortization, Cost	75	74
Intangible assets not subject to amortization, Net Carrying Value	75	74
Patents
Finite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization, Cost	1,525	1,474
Intangible assets subject to amortization, Accumulated Amortization	(515)	(494)
Intangible assets subject to amortization, Net Carrying Value	1,010	980
Purchased Technology
Finite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization, Cost	16,900	16,900
Intangible assets subject to amortization, Accumulated Amortization	(5,164)	(4,694)
Intangible assets subject to amortization, Net Carrying Value	$ 11,736	$ 12,206