In the third quarter of 2019, the Company determined it has five operating and reportable segments: Rides, Eats, Freight, Other Bets and ATG and Other Technology Programs. The change in operating and reportable segments resulted in a reallocation of goodwill to ATG and Other Technology Programs, as the goodwill was generated from previous acquisitions specifically supporting ATG operations. Refer to Note 14 - Segment Information and Geographic Information for further information.

The following table presents the changes in the carrying value of goodwill by segment for the years ended December 31, 2018 and 2019 (in millions):



	As Previously Reported
	Core Platform			Other Bets			Rides		Eats		Freight		Other Bets		ATG and Other Technology Programs		Total Goodwill
Balance as of January 1, 2018	$	39		$	—		$	—	$	—	$	—	$	—	$	—	$	39
Acquisitions	14			100			—		—		—		—		—		114
Balance as of December 31, 2018	53			100			—		—		—		—		—		153
Reallocation due to change in segments	(53		)	(100		)	25		13		—		100		15		—
Acquisitions	—			—			—		—		—		—		14		14
Balance as of December 31, 2019	$	—		$	—		$	25	$	13	$	—	$	100	$	29	$	167

The Company performed an annual test for goodwill impairment in the fourth quarter of the fiscal years ended December 31, 2018 and 2019 and determined that goodwill was not impaired.

The components of intangible assets, net as of December 31, 2018 and 2019 were as follows (in millions except years):



	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Remaining Useful Life - Years
December 31, 2018
Developed technology ⁽¹⁾	$	90	$	(20	)	$	70	4
Patents	15		(3		)	12		9
Other	3		(3		)	—		—
Intangible assets	$	108	$	(26	)	$	82



	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Remaining Useful Life - Years
December 31, 2019
Developed technology ⁽¹⁾	$	94	$	(35	)	$	59	3
Patents	16		(4		)	12		8
Other	3		(3		)	—		—
Intangible assets	$	113	$	(42	)	$	71

⁽¹⁾Developed technology intangible assets include in-process research and development (“IPR&D”), which is not subject to amortization, of $27 million and $31 million as of December 31, 2018 and 2019, respectively.

There have been no impairment charges related to intangible assets recorded in any of the periods presented in the accompanying consolidated financial statements.

Amortization expense for intangible assets subject to amortization was $7 million, $15 million, and $16 million for the years ended December 31, 2017, 2018 and 2019, respectively.

The estimated aggregate future amortization expense for intangible assets subject to amortization as of December 31, 2019 is summarized below (in millions):



	Estimated Future Amortization Expense
Year Ending December 31,
2020	$	12
2021	10
2022	9
2023	4
2024	1
Thereafter	4
Total	$	40