Discontinued Operations - Summary of assets and liabilities by segment (Details) - Discontinued Operations - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Asset:
Total assets from discontinued operations	$ 10,977	$ 40,687
Liabilities:
Total liabilities from discontinued operations	9,391	13,864
Drivetrain
Asset:
Accounts receivable, net	348	519
Inventory, net	498	13,482
Prepaid expenses and other current assets	0	599
Other property and equipment, net	84	3,104
Intangible assets, net	0	628
Right-of-use asset	2,627	4,310
Other assets	47	44
Total assets from discontinued operations	3,604	22,686
Liabilities:
Current portion of long-term debt	0	78
Accounts payable	240	1,407
Lease liability, current	414	790
Accrued expenses and other current liabilities	2,272	4,236
Long-term debt, net of current portion	0	21
Deferred revenue, non-current	208	237
Total liabilities of discontinued operations	2,609	3,459
Total liabilities from discontinued operations	5,743	10,228
XL Grid
Asset:
Accounts receivable, net	3,623	5,958
Inventory, net	1,749	1,780
Prepaid expenses and other current assets	95	131
Other property and equipment, net	152	139
Intangible assets, net	0	1,235
Right-of-use asset	1,719	108
Other assets	35	44
Total assets from discontinued operations	7,373	9,395
Liabilities:
Accounts payable	495	1,695
Lease liability, current	206	59
Accrued expenses and other current liabilities	395	1,379
Deferred revenue, non-current	976	454
Total liabilities of discontinued operations	1,576	49
Total liabilities from discontinued operations	$ 3,648	$ 3,636