Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 1,369	$ 205
OTHER COMPREHENSIVE INCOME (LOSS):
Pension and OPEB prior service costs	(18)	(18)
Amortized losses on derivative hedges	15	3
Change in unrealized gains on available-for-sale securities	(106)	16
Other comprehensive income (loss)	(109)	1
Income tax benefits on other comprehensive income (loss)	(53)	0
Other comprehensive income (loss), net of tax	(56)	1
COMPREHENSIVE INCOME	$ 1,313	$ 206