Financing Activities (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jun. 15, 2030	May 15, 2029
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Issuance Date	Jun. 09, 2020	May 15, 2019
Debt Instrument, Interest Rate, Stated Percentage	3.15%	3.90%
Debt Instrument, Face Amount	$ 600	$ 600
Long-term Debt, Gross	593	594
Debt Issuance Costs, Net	$ 5	$ 5
Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.00%
Debt Instrument, Face Amount	$ 400
Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.45%
Debt Instrument, Face Amount		$ 400

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-Section S99
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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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-Name Accounting Standards Codification
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- Definition

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

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- Definition

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

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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