Note 5. Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The changes in the carrying amount of goodwill, by reporting unit, for the years ended December 31, 2019 and 2018 were as follows (in thousands):

	Balance at December 31, 2018			Acquisitions (Impairments)		Balance at December 31, 2019
Modules	$	407,827		$	—	$	407,827
Accumulated impairment losses	(393,365		)	—		(393,365		)
Total	$	14,462		$	—	$	14,462

	Balance at December 31, 2017			Acquisitions (Impairments)		Balance at December 31, 2018
Modules	$	407,827		$	—	$	407,827
Accumulated impairment losses	(393,365		)	—		(393,365		)
Total	$	14,462		$	—	$	14,462

Schedule of Intangible Assets, Net

The following tables summarize our intangible assets at December 31, 2019 and 2018 (in thousands):

	December 31, 2019
	Gross Amount		Accumulated Amortization			Net Amount
Developed technology	$	97,964	$	(42,344	)	$	55,620
Power purchase agreements	6,486		(972		)	5,514
Patents	7,780		(4,371		)	3,409
Total	$	112,230	$	(47,687	)	$	64,543

	December 31, 2018
	Gross Amount		Accumulated Amortization			Net Amount
Developed technology	$	97,714	$	(33,093	)	$	64,621
Power purchase agreements	6,486		(648		)	5,838
Patents	7,408		(3,705		)	3,703
Total	$	111,608	$	(37,446	)	$	74,162

Schedule of Intangible Asset Future Amortization Expense

Estimated future amortization expense for our definite-lived intangible assets was as follows at December 31, 2019 (in thousands):

	Amortization Expense
2020	$	10,498
2021	10,496
2022	10,471
2023	10,187
2024	10,057
Thereafter	12,834
Total amortization expense	$	64,543