Debt (Schedule of Debt) (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Commercial paper	$ 0	$ 699,000,000
Other bank borrowings	90,000,000	0
Obligations under finance leases	32,000,000	44,000,000
Total debt	19,721,000,000	18,719,000,000
Less commercial paper and other short-term borrowings	0	699,000,000
Less current portion of long-term debt	18,000,000	18,000,000
Total long-term debt, net of current portion	19,703,000,000	18,002,000,000
Net unamortized discount on senior debt	497,000,000	412,000,000
Unamortized deferred financing costs	109,000,000	92,000,000
Decrease (increase) in the carrying value of debt relating to previously settled fair value hedges	5,000,000	6,000,000
Face value of debt	20,330,000,000	19,230,000,000
4.3% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	300,000,000
Stated interest rate	4.30%
4.5% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	499,000,000
Stated interest rate	4.50%
3.875% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	597,000,000
Stated interest rate	3.875%
2.250% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 35,000,000	49,000,000
Stated interest rate	2.25%
3.375% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 415,000,000	698,000,000
Stated interest rate	3.375%
3.125% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 117,000,000	194,000,000
Stated interest rate	3.125%
2.50% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 196,000,000	398,000,000
Stated interest rate	2.50%
3.25% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 141,000,000	181,000,000
Stated interest rate	3.25%
2.90% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 242,000,000	396,000,000
Stated interest rate	2.90%
4.25% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 836,000,000	1,242,000,000
Stated interest rate	4.25%
7.875% Debentures due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 139,000,000	187,000,000
Stated interest rate	7.875%
7.125% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 35,000,000	46,000,000
Stated interest rate	7.125%
3.875% Senior Notes due 2024 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 490,000,000	489,000,000
Stated interest rate	3.875%
3.70% Senior Notes due 2024 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 598,000,000	598,000,000
Stated interest rate	3.70%
3.50% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 593,000,000	592,000,000
Stated interest rate	3.50%
4.75% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,238,000,000	0
Stated interest rate	4.75%
4.0% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 790,000,000	789,000,000
Stated interest rate	4.00%
3.45% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 123,000,000	123,000,000
Stated interest rate	3.45%
2.90% Senior Notes due 2027 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 689,000,000	688,000,000
Stated interest rate	2.90%
3.375% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 495,000,000	494,000,000
Stated interest rate	3.375%
3.70% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 491,000,000	491,000,000
Stated interest rate	3.70%
4.20% Senior Notes due 2029 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 493,000,000	493,000,000
Stated interest rate	4.20%
7.875% Senior Debentures due 2030 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 831,000,000	831,000,000
Stated interest rate	7.875%
4.95% Senior Notes due 2031 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,219,000,000	0
Stated interest rate	4.95%
4.20% Senior Notes due 2032 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 969,000,000	0
Stated interest rate	4.20%
5.50% Senior Debentures due 2033 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 426,000,000	426,000,000
Stated interest rate	5.50%
4.85% Senior Debentures due 2034 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 87,000,000	87,000,000
Stated interest rate	4.85%
6.875% Senior Debentures due 2036 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,069,000,000	1,068,000,000
Stated interest rate	6.875%
6.75% Senior Debentures due 2037 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 75,000,000	75,000,000
Stated interest rate	6.75%
5.90% Senior Notes due 2040 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 298,000,000	297,000,000
Stated interest rate	5.90%
4.50% Senior Debentures due 2042 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 45,000,000	45,000,000
Stated interest rate	4.50%
4.85% Senior Notes due 2042 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 487,000,000	486,000,000
Stated interest rate	4.85%
4.375% Senior Debentures due 2043 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,114,000,000	1,109,000,000
Stated interest rate	4.375%
4.875% Senior Debentures due 2043 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 18,000,000	18,000,000
Stated interest rate	4.875%
5.85% Senior Debentures due 2043 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,232,000,000	1,231,000,000
Stated interest rate	5.85%
5.25% Senior Debentures due 2044 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 345,000,000	345,000,000
Stated interest rate	5.25%
4.90% Senior Notes due 2044 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 540,000,000	539,000,000
Stated interest rate	4.90%
4.60% Senior Notes due 2045 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 589,000,000	589,000,000
Stated interest rate	4.60%
4.95% Senior Notes due 2050 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 942,000,000	0
Stated interest rate	4.95%
5.875% Junior Subordinated Debentures due 2057 [Member]
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 514,000,000	643,000,000
Stated interest rate	5.875%
6.25% Junior Subordinated Debentures due 2057 [Member]
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 643,000,000	$ 643,000,000
Stated interest rate	6.25%

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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