Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Aug. 19, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 5,197		$ 3,566
3.60% Senior Notes Due 2022 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 250		249
Stated interest rate (percent)	3.60%
3.6% Senior Notes Due 2026 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 744		744
Stated interest rate (percent)	3.60%
Loan related to tax-exempt waste disposal revenue bonds due 2027 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 11		11
1.625% Senior Notes Due 2029 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 802		849
Stated interest rate (percent)	1.625%
3.375% Senior Notes Due 2030 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 296		296
Stated interest rate (percent)	3.375%
3.50% Senior Notes Due 2032 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 249		249
Stated interest rate (percent)	3.50%
5.0% Senior Notes Due 2046 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 678		677
Stated interest rate (percent)	5.00%
4.375% Senior Notes Due 2047 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 492		491
Stated interest rate (percent)	4.375%
8.73% Senior Notes Due 2022 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 24		0
Stated interest rate (percent)	8.73%
Term Loan Due 2026 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 6		0
Stated interest rate (percent)	0.20%
0.875% Senior Notes Due 2024 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 298		0
Stated interest rate (percent)	0.875%	0.875%
2.875% Senior Notes Due 2041 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 339		0
Stated interest rate (percent)	2.875%	2.875%
3.125% Senior Notes Due 2051 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 577		0
Stated interest rate (percent)	3.125%	3.125%
3.75% Senior Notes Due 2061 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 431		0
Stated interest rate (percent)	3.375%	3.375%
Fair Value [Member] | 3.60% Senior Notes Due 2022 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 254		259
Fair Value [Member] | 3.6% Senior Notes Due 2026 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	825		846
Fair Value [Member] | Loan related to tax-exempt waste disposal revenue bonds due 2027 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	11		11
Fair Value [Member] | 1.625% Senior Notes Due 2029 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	860		897
Fair Value [Member] | 3.375% Senior Notes Due 2030 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	325		332
Fair Value [Member] | 3.50% Senior Notes Due 2032 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	276		276
Fair Value [Member] | 5.0% Senior Notes Due 2046 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	872		905
Fair Value [Member] | 4.375% Senior Notes Due 2047 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	577		597
Fair Value [Member] | 8.73% Senior Notes Due 2022 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	24		0
Fair Value [Member] | Term Loan Due 2026 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	6		0
Fair Value [Member] | 0.875% Senior Notes Due 2024 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	301		0
Fair Value [Member] | 2.875% Senior Notes Due 2041 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	337		$ 0
Fair Value [Member] | 3.125% Senior Notes Due 2051 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	571
Fair Value [Member] | 3.75% Senior Notes Due 2061 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 427