Discontinued Operations - Summary of income (loss) by segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses:
Net loss from discontinued operations	$ (40,112)	$ (23,812)
Drivetrain | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	2,419	2,839
Operating expenses:
Cost of revenues - inventory and other direct costs	14,038	7,938
Engineering, research, and development	9,819	10,775
Selling, general, and administrative expenses	8,041	7,955
Total operating expenses	31,898	26,668
Loss from operations	(29,479)	(23,829)
Loss on asset disposal	935	0
Net loss from discontinued operations	(30,414)	(23,829)
XL Grid | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	12,279	12,761
Operating expenses:
Cost of revenues - inventory and other direct costs	8,577	8,358
Engineering, research, and development	0	0
Selling, general, and administrative expenses	4,794	4,386
Total operating expenses	13,371	12,744
Net loss from discontinued operations	$ (1,092)	$ 17