Debt (Schedule of Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Other bank borrowings	$ 115	$ 95
Obligations under finance leases	36	26
Total debt	17,787	19,733
Less current portion of long-term debt	19	16
Total long-term debt, net of current portion	17,768	19,717
Net unamortized discount on senior debt	481	491
Unamortized deferred financing costs	102	107
Face value of debt	18,370	20,330
2.250% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	35
Stated interest rate	2.25%
3.375% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	415
Stated interest rate	3.375%
3.125% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	117
Stated interest rate	3.125%
2.50% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	196
Stated interest rate	2.50%
3.25% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	141
Stated interest rate	3.25%
2.90% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	242
Stated interest rate	2.90%
4.25% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 0	837
Stated interest rate	4.25%
7.875% Debentures due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 139	139
Stated interest rate	7.875%
7.125% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 35	35
Stated interest rate	7.125%
3.875% Senior Notes due 2024 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 490	490
Stated interest rate	3.875%
3.70% Senior Notes due 2024 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 598	598
Stated interest rate	3.70%
3.50% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 597	596
Stated interest rate	3.50%
4.75% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,240	1,239
Stated interest rate	4.75%
4.0% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 791	791
Stated interest rate	4.00%
3.45% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 123	123
Stated interest rate	3.45%
2.90% Senior Notes due 2027 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 691	691
Stated interest rate	2.90%
3.375% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 495	495
Stated interest rate	3.375%
3.70% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 492	492
Stated interest rate	3.70%
4.20% Senior Notes due 2029 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 494	493
Stated interest rate	4.20%
7.875% Senior Debentures due 2030 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 831	831
Stated interest rate	7.875%
4.95% Senior Notes due 2031 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,221	1,220
Stated interest rate	4.95%
4.20% Senior Notes due 2032 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 970	969
Stated interest rate	4.20%
5.50% Senior Debentures due 2033 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 427	427
Stated interest rate	5.50%
4.85% Senior Debentures due 2034 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 87	87
Stated interest rate	4.85%
6.875% Senior Debentures due 2036 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,069	1,069
Stated interest rate	6.875%
6.75% Senior Debentures due 2037 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 75	75
Stated interest rate	6.75%
5.90% Senior Notes due 2040 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 298	298
Stated interest rate	5.90%
4.50% Senior Debentures due 2042 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 45	45
Stated interest rate	4.50%
4.85% Senior Notes due 2042 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 487	487
Stated interest rate	4.85%
4.375% Senior Debentures due 2043 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,117	1,116
Stated interest rate	4.375%
4.875% Senior Debentures due 2043 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 18	18
Stated interest rate	4.875%
5.85% Senior Debentures due 2043 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 1,232	1,232
Stated interest rate	5.85%
5.25% Senior Debentures due 2044 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 345	345
Stated interest rate	5.25%
4.90% Senior Notes due 2044 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 540	540
Stated interest rate	4.90%
4.60% Senior Notes due 2045 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 589	589
Stated interest rate	4.60%
4.95% Senior Notes due 2050 [Member]
Debt Instrument [Line Items]
Carrying value of senior debt	$ 943	942
Stated interest rate	4.95%
5.875% Junior Subordinated Debentures due 2057 [Member]
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 514	514
Stated interest rate	5.875%
6.25% Junior Subordinated Debentures due 2057 [Member]
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 643	$ 643
Stated interest rate	6.25%

Amount of short-term and long-term debt and lease obligation.

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