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Debt (Debt Redemption) (Narrative) (Details) - USD ($) $ in Millions			3 Months Ended	10 Months Ended	12 Months Ended
	Nov. 01, 2020	Oct. 15, 2019	Dec. 31, 2019	Nov. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Extinguishment of Debt [Line Items]
Early extinguishment of debt					$ (2)	$ (85)
4.0% Notes Due 2021 [Member]
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchase Date	Nov. 01, 2020
Interest rate on note	4.00%			4.00%
Principal outstanding	$ 500			$ 500
Redemption price percentage of principal amount				100.00%
6.125% Notes Due 2020 [Member]
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchase Date		Oct. 15, 2019
Early extinguishment of debt			$ 2
Interest rate on note		6.125%
Principal outstanding		$ 163

X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

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- Definition

Fair value amount of debt instrument that was repurchased.

+ References

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- Definition

Date the debt instrument was repurchased, in CCYY-MM-DD format.

+ References

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- Definition

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+ References

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- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=117329964&loc=d3e12355-112629

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

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