Discontinued Operations - Net income (loss) from discontinued operation by discontinued operation (Details) - Discontinued Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
XL Grid
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	$ 0	$ 2,202	$ 149	$ 6,367
Operating expenses:
Cost of revenues - inventory and other direct costs	0	1,529	148	4,517
Loss on asset disposal	0	0	(742)	0
Selling, general, and administrative expenses	0	2,126	743	4,744
Total operating expenses	0	3,655	149	9,261
Net loss from discontinued operations	0	(1,453)	0	(2,894)
Drivetrain
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	12	808	20	1,406
Operating expenses:
Cost of revenues - inventory and other direct costs	168	916	29	3,124
Engineering, research, and development	0	2,404	0	5,393
Selling, general, and administrative expenses	0	902	0	2,199
Other	27	(16)	4,040	(16)
Total operating expenses	195	4,206	4,069	10,700
Net loss from discontinued operations	$ (183)	$ (3,398)	$ (4,049)	$ (9,294)