Debt (Interest and Facility) (Details) $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($)
6.375% Senior Notes due December 2021
Debt
Debt instrument interest rate stated percentage	6.375%
Interest rate, as adjusted (as a percent)	8.375%
3.80% Senior Notes due October 2022
Debt
Debt instrument interest rate stated percentage	3.80%
Interest rate, as adjusted (as a percent)	5.80%
7.35% Senior Notes due December 2041
Debt
Debt instrument interest rate stated percentage	7.35%
Interest rate, as adjusted (as a percent)	9.35%
Five-Year Revolving Credit Facility
Debt
Borrowing capacity, maximum	$ 1,300
Commitment fee percentage at period end	0.875%
Credit facility amount outstanding	$ 0
Letters of credit issued and outstanding	25
Credit facility available borrowing capacity	$ 1,300
Five-Year Revolving Credit Facility \| Minimum
Debt
Commitment fee percentage at period end	0.375%
Five-Year Revolving Credit Facility \| Maximum
Debt
Commitment fee percentage at period end	1.00%
Five-Year Revolving Credit Facility \| Adjusted LIBOR
Debt
Spread on variable rate basis (as a percent)	3.375%
Percentage reduction to the calculated variable rate	1.00%
Five-Year Revolving Credit Facility \| Adjusted LIBOR \| Minimum
Debt
Spread on variable rate basis (as a percent)	2.625%
Five-Year Revolving Credit Facility \| Adjusted LIBOR \| Maximum
Debt
Spread on variable rate basis (as a percent)	3.375%

The percentage reduction to the calculated variable rate.

No definition available.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

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- Definition

The average effective interest rate during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: 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

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

+ References

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- Definition

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.

+ References

No definition available.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
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-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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