Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Adoption of new accounting standard for reclassification of income taxes (refer to Note 11)	$ 0		$ 0
Net income	664	$ 245	2,516	$ 886
Other comprehensive (loss) income, net of taxes:
Unrealized gains on securities	0	0	0	2
Defined benefit plans:
Actuarial gains arising during the period, net of taxes of $48 million for the nine months ended September 30, 2017	0	0	0	69
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax		0		48
Amortization of unrecognized amounts included in net periodic benefit costs	13	12	36	42
Foreign exchange (losses) gains	(1)	1	(2)	0
Other comprehensive income	12	13	34	113
Total comprehensive income	676	258	2,550	999
Total comprehensive (income) loss attributable to noncontrolling interests	(109)	35	(399)	(118)
Total comprehensive income (loss)	567	293	2,151	881
AOCI Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Adoption of new accounting standard for reclassification of income taxes (refer to Note 11)	(79)		(79)
Defined benefit plans:
Other comprehensive income	$ 11	$ 13	$ 34	$ 105