Acquisitions and Divestitures - Provisional Estimates of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jun. 11, 2021	Jun. 10, 2021	Jan. 15, 2021	Jan. 08, 2021	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets acquired
Goodwill					$ 111,458	$ 1,165	$ 23,344
Solectrac
Purchase Price
Cash paid at closing, including working capital estimates	$ 17,745
Fair value of previously held interest	5,287
Fair value of contingent consideration	1,639
Total purchase consideration	24,671
Assets acquired
Current assets	3,011
Property, plant and equipment	30
Other assets	45
Goodwill	16,787
Total assets acquired	26,893
Liabilities assumed:
Current liabilities	(509)
Deferred tax liability	(1,713)
Total liabilities assumed	(2,222)
Net assets acquired	$ 24,671
Weighted average useful life	7 years 4 months 24 days
Solectrac | Trade name
Assets acquired
Intangible assets	$ 4,570
Liabilities assumed:
Weighted average useful life	6 years
Solectrac | Technology
Assets acquired
Intangible assets	$ 2,450
Liabilities assumed:
Weighted average useful life	10 years
US Hybrid
Purchase Price
Cash paid at closing, including working capital estimates		$ 30,139
Fair value of common stock		20,877
Total purchase consideration		51,016
Assets acquired
Current assets		4,547
Property, plant and equipment		5
Other assets		51
Goodwill		41,446
Total assets acquired		53,419
Liabilities assumed:
Current liabilities		(1,601)
Deferred tax liability		(802)
Total liabilities assumed		(2,403)
Net assets acquired		$ 51,016
Weighted average useful life		11 years
US Hybrid | Trade name
Assets acquired
Intangible assets		$ 1,740
Liabilities assumed:
Weighted average useful life		7 years
US Hybrid | Technology
Assets acquired
Intangible assets		$ 5,110
Liabilities assumed:
Weighted average useful life		13 years
US Hybrid | Non-compete
Assets acquired
Intangible assets		$ 520
Liabilities assumed:
Weighted average useful life		5 years
Timios
Purchase Price
Cash paid at closing, including working capital estimates				$ 46,576
Total purchase consideration				46,576
Assets acquired
Current assets				7,292
Property, plant and equipment				429
Other assets				48
Indefinite lived title plant				500
Goodwill				24,252
Total assets acquired				56,091
Liabilities assumed:
Current liabilities				(4,306)
Deferred tax liability				(5,209)
Total liabilities assumed				(9,515)
Net assets acquired				$ 46,576
Weighted average useful life				10 years
Timios | Trade name
Assets acquired
Intangible assets				$ 7,780
Liabilities assumed:
Weighted average useful life				15 years
Timios | Lender relationships
Assets acquired
Intangible assets				$ 14,790
Liabilities assumed:
Weighted average useful life				7 years
Timios | Licenses
Assets acquired
Intangible assets				$ 1,000
Liabilities assumed:
Weighted average useful life				15 years
WAVE
Purchase Price
Cash paid at closing, including working capital estimates			$ 15,000
Fair value of common stock			32,377
Fair value of contingent consideration			7,657
Total purchase consideration			55,034
Assets acquired
Current assets			2,130
Goodwill			34,142
Total assets acquired			61,902
Liabilities assumed:
Current liabilities			(3,778)
Deferred tax liability			(3,090)
Total liabilities assumed			(6,868)
Net assets acquired			$ 55,034
Weighted average useful life			14 years 6 months
WAVE | Trade name
Assets acquired
Intangible assets			$ 12,630
Liabilities assumed:
Weighted average useful life			15 years
WAVE | Patent
Assets acquired
Intangible assets			$ 13,000
Liabilities assumed:
Weighted average useful life			14 years