Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 88	$ 510	$ 991
Derivatives qualifying as cash flow hedges:
(Loss) gain on derivatives qualifying as cash flow hedges, net of tax (benefit) of ($10), $2, and $4, respectively	(14)	1	(5)
Less: Reclassification adjustment for loss on derivatives included in net income, net of tax (benefit) of ($3), ($4), and $2, respectively	(3)	(6)	(9)
Derivatives qualifying as cash flow hedges, net of tax (benefit) of ($7), $6, and $2, respectively	(11)	7	4
Pension and postretirement benefits:
Changes in pension and postretirement benefits, net of tax (benefit) of ($27), ($19), and $6, respectively	(65)	(34)	74
Less: Amortization of prior service benefit cost included in net periodic benefit cost, net of tax (benefit) of ($10), ($7), and ($1), respectively	(14)	(9)	(7)
Pension and postretirement benefits, net of tax (benefit) of ($17), ($12), and $7, respectively	(51)	(25)	81
Foreign currency translation:
Changes in foreign currency translation, net of tax of $0 in all periods	58	(53)	(67)
Less: Translation loss realized upon sale of foreign entities, net of tax of $0 in all periods	0	0	(6)
Foreign currency translation, net of tax of $0 in all periods	58	(53)	(61)
Other comprehensive (loss) income, net of tax	(4)	(71)	24
Comprehensive income	$ 84	$ 439	$ 1,015