Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Cash Equivalents, at Carrying Value	$ 1,372	$ 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	1,372	1,464
Available-for-sale Debt Securities, Amortized Cost Basis, Current	106	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	(1)	0
Debt Securities, Available-for-sale, Current	105	45
Debt Securities, Available-for-sale, Amortized Cost	1,526	1,495
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	123	154
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(26)	(15)
Debt Securities, Available-for-sale	1,623	1,634
Equity Securities, Amortized Cost Basis	7	6
Equity Securities, Accumulated Gross Unrealized Gain, Before Tax	25	34
Equity Securities, Accumulated Gross Unrealized Loss, Before Tax	0	0
Equity Securities, Fair Value	32	40
Other Investments and Securities, at Cost	1,533	1,501
Other Investments and Securities, Accumulated Gross Unrealized Gain, Before Tax	148	188
Other Investments and Securities, Accumulated Gross Unrealized Loss, Before Tax	(26)	(15)
Investments, Fair Value Disclosure	1,655	1,674
Cash Equivalents, Marketable Securities and Other Investments, Amortized Cost Basis	3,011	3,010
Cash Equivalents, Marketable Securities and Other Investments, Accumulated Gross Unrealized Gain, Before Tax	148	188
Cash Equivalents, Marketable Securities and Other Investments, Accumulated Gross Unrealized Loss, Before Tax	(27)	(15)
Cash Equivalents, Marketable Securities and Other Investments, Fair Value	3,132	3,183
Long-term Debt	(15,538)	(16,951)
Long Term Debt, Accumulated Gross Unrealized Gain, Before Tax	16	6
Long Term Debt, Accumulated Gross Unrealized Loss, Before Tax	(3,160)	(3,659)
Long-term Debt, Fair Value	(18,682)	(20,604)
Derivative Assets (Liabilities), Accumulated Gross Unrealized Gain, Before Tax	208	173
Derivative Assets (Liabilities), Accumulated Gross Unrealized Loss, Before Tax	(372)	(350)
Derivative Assets (Liabilities), at Fair Value, Net	(164)	(177)
Long Term Debt, Accumulated Fair Value Adjustment	45	69
Derivative, Amount of Hedged Item	2,500	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	(186)	(182)
Derivative Assets (Liabilities), at Fair Value, Net	(186)	(141)
Foreign Exchange Contract [Member]
Debt Securities, Available-for-sale [Line Items]
Derivative Assets (Liabilities), Accumulated Gross Unrealized Gain, Before Tax	17	69
Derivative Assets (Liabilities), Accumulated Gross Unrealized Loss, Before Tax	(64)	(84)
Derivative Assets (Liabilities), at Fair Value, Net	(47)	(15)
Commodity Contract [Member]
Debt Securities, Available-for-sale [Line Items]
Derivative Assets (Liabilities), Accumulated Gross Unrealized Gain, Before Tax	191	63
Derivative Assets (Liabilities), Accumulated Gross Unrealized Loss, Before Tax	(122)	(84)
Derivative Assets (Liabilities), at Fair Value, Net	69	(21)
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	592	673
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	23	35
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(21)	(10)
Debt Securities, Available-for-sale	594	698
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	934	822
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	100	119
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(5)	(5)
Debt Securities, Available-for-sale	1,029	936
Held-to-maturity Securities
Debt Securities, Available-for-sale [Line Items]
Cash Equivalents, at Carrying Value	644	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	644	980
Money Market Funds
Debt Securities, Available-for-sale [Line Items]
Cash Equivalents, at Carrying Value	728	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	$ 728	$ 484