Goodwill and Other Intangible Assets
 12 Months Ended
Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]  
Goodwill and Other Intangible Assets
Note 8: Goodwill and Other Intangible Assets
Goodwill
Presented in the table below are the changes in the carrying value of goodwill for the years ended December 31, 2019 and 2018:
 
Regulated Businesses
 
Market-Based Businesses
 
Consolidated
 
Cost
 
Accumulated Impairment
 
Cost
 
Accumulated Impairment
 
Cost
 
Accumulated Impairment
 
Total Net
Balance as of January 1, 2018
$
3,492

 
$
(2,332
)
 
$
327

 
$
(108
)
 
$
3,819

 
$
(2,440
)
 
$
1,379

Goodwill from acquisitions
2

 
—

 
247

 
—

 
249

 
—

 
249

Goodwill impairment charge
—

 
—

 
—

 
(53
)
 
—

 
(53
)
 
(53
)
Balance as of December 31, 2018
$
3,494

 
$
(2,332
)
 
$
574

 
$
(161
)
 
$
4,068

 
$
(2,493
)
 
$
1,575

Goodwill from acquisitions
3

 
—

 
—

 
—

 
3

 
—

 
3

Goodwill reduced through sale of Keystone operations
—

 
—

 
(91
)
 
53

 
(91
)
 
53

 
(38
)
Less: Goodwill included in assets held for sale (a)
(39
)
 
—

 
—

 
—

 
(39
)
 
—

 
(39
)
Balance as of December 31, 2019
$
3,458

 
$
(2,332
)
 
$
483

 
$
(108
)
 
$
3,941

 
$
(2,440
)
 
$
1,501


(a)
This goodwill is related to the pending transactions contemplated by the Stock Purchase Agreement and is included in assets held for sale on the Consolidated Balance Sheets. See Note 4—Acquisitions and Divestitures for additional information.
In 2019, the Company acquired goodwill of $3 million associated with three of its acquisitions in the Regulated Businesses segment. Additionally, as part of the sale of the Company’s Keystone operations on December 12, 2019, the Company reduced goodwill, net, by $38 million. See Note 4—Acquisitions and Divestitures for additional information.
The Company completed its annual impairment testing of goodwill as of November 30, 2019, which included quantitative assessments of its Regulated Businesses, Homeowner Services Group and Military Services Group reporting units. Based on these assessments, the Company determined that there were no factors present that would indicate that the fair value of these reporting units was less than their respective carrying values as of November 30, 2019.
In 2018, the Company acquired goodwill of $247 million associated with its acquisition of Pivotal, which was allocated to the Homeowner Services Group reporting unit, within the Market-Based Businesses. Additionally, the Company acquired goodwill of $2 million associated with one of its acquisitions in the Regulated Businesses segment.
During the third quarter of 2018, as a result of the narrowing the scope of the Company’s former Keystone operations, the Company concluded there were indicators that the Keystone reporting unit may have been impaired. Accordingly, impairment testing was performed as part of the preparation of the Company’s Consolidated Financial Statements during the third quarter of 2018. The results of this impairment test showed the fair value of the former Keystone reporting unit was lower than its carrying value, resulting in a non-cash, pre-tax goodwill impairment charge of $53 million. Additionally, the impairment test showed the fair value of the former Keystone reporting unit’s customer relationship intangible asset was lower than its carrying value, resulting in a non-cash, pre-tax impairment charge of $4 million. In the aggregate, a non-cash, pre-tax impairment charge of $57 million was recorded in impairment charge on the Consolidated Statement of Operations for the year ended December 31, 2018, of which, $54 million was attributable to the Company, after adjustment for noncontrolling interest.
Intangible Assets
Presented in the tables below are the gross carrying value and accumulated amortization of the finite-lived intangible assets held by the Company as of December 31:

2018
 
Disposals (a)
 
2019
Customer relationships
$
86

 
$
(8
)
 
$
78

Other intangible assets
13

 
—

 
13

Total gross carrying value
$
99

 
$
(8
)
 
$
91

(a)
The disposals relate to customer relationship intangible assets disposed of as part of the sale of the Company’s Keystone operations on December 12, 2019. See Note 4—Acquisitions and Divestitures for additional information.

2018
 
Amortization
 
Disposals (a)
 
2019
Customer relationships
$
(13
)
 
$
(12
)
 
$
5

 
$
(20
)
Other intangible assets
(2
)
 
(2
)
 
—

 
(4
)
Total accumulated amortization
$
(15
)
 
$
(14
)
 
$
5

 
$
(24
)
Total intangible assets, net
$
84

 
 
 
 
 
$
67


(a)
The disposals relate to customer relationship intangible assets disposed of as part of the sale of the Company’s Keystone operations on December 12, 2019. See Note 4—Acquisitions and Divestitures for additional information.
Intangible asset amortization expense amounted to $14 million, $12 million and $4 million for the years ended December 31, 2019, 2018 and 2017, respectively. Estimated amortization expense for the next five years subsequent to December 31, 2019 is as follows:
 
Amount
2020
$
12

2021
10

2022
9

2023
6

2024
5