Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 1,079	$ 912	$ 1,348
OTHER COMPREHENSIVE INCOME (LOSS):
Pension and OPEB prior service costs	(34)	(31)	(83)
Amortized losses on derivative hedges	1	2	21
Change in unrealized gains on available-for-sale securities	0	0	(106)
Other comprehensive loss	(33)	(29)	(168)
Income tax benefits on other comprehensive loss	(8)	(8)	(67)
Other comprehensive loss, net of tax	(25)	(21)	(101)
COMPREHENSIVE INCOME	$ 1,054	$ 891	$ 1,247