Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Certain Relationships and Related Party Transactions - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	May 07, 2019	Sep. 30, 2019	Sep. 30, 2019
2016 Repurchase Program
Related Party Transaction [Line Items]
Common stock, repurchased during the period		$ 46	$ 331
Ashe Capital Management, LP
Related Party Transaction [Line Items]
Common stock repurchased during the period (shares)	4,977,043
Ashe Capital Management, LP \| 2016 Repurchase Program
Related Party Transaction [Line Items]
Common stock, repurchased during the period	$ 232