CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$ 152	$ 191
PP&E, accumulated depreciation	$ 32,917	$ 31,596
Preferred stock-non-redeemable, par value (in dollars per share)	$ 25.00	$ 25.00
Preferred stock-non-redeemable, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock-non-redeemable, shares issued (in shares)	7,000	7,000
Preferred stock-non-redeemable, shares outstanding (in shares)	7,000	7,000
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	2,200,000,000	2,200,000,000
Common stock, shares issued (in shares)	1,105,186,000	1,096,921,000
Common stock, shares outstanding (in shares)	1,105,186,000	1,096,921,000