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v3.20.1

Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2020 | Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 4,432 | $ 3,445
3.60% Senior Notes Due 2022 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 249 | 249
Debt Instrument Maturity | 2022 |
Stated interest rate (percent) | 3.60% |
3.6% Senior Notes Due 2026 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 743 | 742
Debt Instrument Maturity | 2026 |
Stated interest rate (percent) | 3.60% |
Loan related to tax-exempt waste disposal revenue bonds due 2027 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 11 | 11
Debt Instrument Maturity | 2027 |
6 1/2% GO Zone Senior Notes Due 2029 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 99 | 99
Debt Instrument Maturity | 2029 |
Stated interest rate (percent) | 6.50% |
2035 GO Zone 6 1/2% Notes [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 88 | 88
Debt Instrument Maturity | 2035 |
Stated interest rate (percent) | 6.50% |
2035 IKE Zone 6 1/2% Notes [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 65 | 65
Debt Instrument Maturity | 2035 |
Stated interest rate (percent) | 6.50% |
5.0% Senior Notes Due 2046 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 677 | 677
Debt Instrument Maturity | 2046 |
Stated interest rate (percent) | 5.00% |
4.375% Senior Notes Due 2047 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 491 | 491
Debt Instrument Maturity | 2047 |
Stated interest rate (percent) | 4.375% |
3.50% Senior Notes Due 2032 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 249 | 249
Debt Instrument Maturity | 2032 |
Stated interest rate (percent) | 3.50% |
1.625% Senior Notes Due 2029 | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | $ 760 | 774
Debt Instrument Maturity | 2029 |
Stated interest rate (percent) | 1.625% |
Fair Value [Member] | 3.60% Senior Notes Due 2022 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | $ 244 | 255
Fair Value [Member] | 3.6% Senior Notes Due 2026 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 687 | 777
Fair Value [Member] | Loan related to tax-exempt waste disposal revenue bonds due 2027 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 11 | 11
Fair Value [Member] | 6 1/2% GO Zone Senior Notes Due 2029 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 98 | 103
Fair Value [Member] | 2035 GO Zone 6 1/2% Notes [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 92 | 92
Fair Value [Member] | 2035 IKE Zone 6 1/2% Notes [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 65 | 68
Fair Value [Member] | 5.0% Senior Notes Due 2046 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 651 | 761
Fair Value [Member] | 4.375% Senior Notes Due 2047 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 395 | 505
Fair Value [Member] | 3.50% Senior Notes Due 2032 [Member] | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 239 | 267
Fair Value [Member] | 1.625% Senior Notes Due 2029 | Senior Notes [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | 688 | 785
Revolving Credit Facility [Member] | Credit Agreement [Member] | Line of Credit [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term Debt | 1,000 | 0
Revolving Credit Facility [Member] | Fair Value [Member] | Credit Agreement [Member] | Line of Credit [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fair Value | $ 1,000 | $ 0

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