Goodwill increased $130 million from $68 million as of December 31, 2018 to $198 million as of December 31, 2019 primarily due to completed business combinations during the year ended December 31, 2019 (see Note 3, Business Combinations). There were no accumulated impairment losses as of December 31, 2019 and 2018.

Information regarding our intangible assets including assets recognized from our acquisitions was as follows (in millions):

	December 31, 2019										December 31, 2018
	Gross Carrying Amount		Accumulated Amortization			Other			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Other			Net Carrying Amount
Finite-lived intangible assets:
Developed technology	$	291	$	(72	)	$	1		$	220	$	152	$	(40	)	$	1		$	113
Trade names		3		(1	)		1			3		45		(44	)		—			1
Favorable contracts and leases, net		113		(24	)		—			89		113		(17	)		—			96
Other		38		(16	)		—			22		36		(12	)		1			25
Total finite-lived intangible assets		445		(113	)		2			334		346		(113	)		2			235
Indefinite-lived intangible assets:
Gigafactory Nevada water rights		5		—			—			5		—		—			—			—
In-process research and development (“IPR&D”)		60		—			(60	)		—		60		—			(13	)		47
Total indefinite-lived intangible assets		65		—			(60	)		5		60		—			(13	)		47
Total intangible assets	$	510	$	(113	)	$	(58	)	$	339	$	406	$	(113	)	$	(11	)	$	282

During 2019, the Company determined to abandon further development efforts on the IPR&D and therefore impaired the remaining $47 million in restructuring and other expenses in the consolidated statement of operations. Amortization expense during the years ended December 31, 2019, 2018 and 2017 was $44 million, $66 million and $40 million, respectively.

Total future amortization expense for finite-lived intangible assets was estimated as follows (in millions):