Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Cash Equivalents, at Carrying Value	$ 1,053	$ 1,464
Cash Equivalents, Accumulated Gross Unrealized Gain, Before Tax	0	0
Cash Equivalents, Accumulated Gross Unrealized Loss, Before Tax	0	0
Cash Equivalents, Fair Value	1,053	1,464
Available-for-sale Debt Securities, Amortized Cost Basis, Current	72	45
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, Current, before Tax	0	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, Current, before Tax	0	0
Debt Securities, Available-for-sale, Current	72	45
Debt Securities, Available-for-sale, Amortized Cost	1,422	1,495
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	109	154
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(36)	(15)
Debt Securities, Available-for-sale	1,495	1,634
Equity Securities, Amortized Cost Basis	8	6
Equity Securities, Accumulated Gross Unrealized Gain, Before Tax	26	34
Equity Securities, Accumulated Gross Unrealized Loss, Before Tax	0	0
Equity Securities, Fair Value	34	40
Other Investments and Securities, at Cost	1,430	1,501
Other Investments and Securities, Accumulated Gross Unrealized Gain, Before Tax	135	188
Other Investments and Securities, Accumulated Gross Unrealized Loss, Before Tax	(36)	(15)
Investments, Fair Value Disclosure	1,529	1,674
Cash Equivalents, Marketable Securities and Other Investments, Amortized Cost Basis	2,555	3,010
Cash Equivalents, Marketable Securities and Other Investments, Accumulated Gross Unrealized Gain, Before Tax	135	188
Cash Equivalents, Marketable Securities and Other Investments, Accumulated Gross Unrealized Loss, Before Tax	(36)	(15)
Cash Equivalents, Marketable Securities and Other Investments, Fair Value	2,654	3,183
Long-term Debt	(16,692)	(16,951)
Long Term Debt, Accumulated Gross Unrealized Gain, Before Tax	58	6
Long Term Debt, Accumulated Gross Unrealized Loss, Before Tax	(2,685)	(3,659)
Long-term Debt, Fair Value	(19,319)	(20,604)
Derivative Assets (Liabilities), Accumulated Gross Unrealized Gain, Before Tax	98	173
Derivative Assets (Liabilities), Accumulated Gross Unrealized Loss, Before Tax	(302)	(350)
Derivative Assets (Liabilities), at Fair Value, Net	(204)	(177)
Long Term Debt, Accumulated Fair Value Adjustment	43	69
Derivative, Amount of Hedged Item	3,314
Interest Rate Contract [Member]
Debt Securities, Available-for-sale [Line Items]
Derivative Assets (Liabilities), Accumulated Gross Unrealized Gain, Before Tax	0	41
Derivative Assets (Liabilities), Accumulated Gross Unrealized Loss, Before Tax	(141)	(182)
Derivative Assets (Liabilities), at Fair Value, Net	(141)	(141)
Foreign Exchange Contract [Member]
Debt Securities, Available-for-sale [Line Items]
Derivative Assets (Liabilities), Accumulated Gross Unrealized Gain, Before Tax	23	69
Derivative Assets (Liabilities), Accumulated Gross Unrealized Loss, Before Tax	(94)	(84)
Derivative Assets (Liabilities), at Fair Value, Net	(71)	(15)
Commodity Contract [Member]
Debt Securities, Available-for-sale [Line Items]
Derivative Assets (Liabilities), Accumulated Gross Unrealized Gain, Before Tax	75	63
Derivative Assets (Liabilities), Accumulated Gross Unrealized Loss, Before Tax	(67)	(84)
Derivative Assets (Liabilities), at Fair Value, Net	8	(21)
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	570	673
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	17	35
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(29)	(10)
Debt Securities, Available-for-sale	558	698
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	852	822
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	92	119
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(7)	(5)
Debt Securities, Available-for-sale	937	936
Held-to-maturity Securities
Debt Securities, Available-for-sale [Line Items]
Cash Equivalents, at Carrying Value	405	980
Cash Equivalents, Accumulated Gross Unrealized Gain, Before Tax	0	0
Cash Equivalents, Accumulated Gross Unrealized Loss, Before Tax	0	0
Cash Equivalents, Fair Value	405	980
Money Market Funds
Debt Securities, Available-for-sale [Line Items]
Cash Equivalents, at Carrying Value	648	484
Cash Equivalents, Accumulated Gross Unrealized Gain, Before Tax	0	0
Cash Equivalents, Accumulated Gross Unrealized Loss, Before Tax	0	0
Cash Equivalents, Fair Value	$ 648	$ 484