Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ (44)	$ (41)	$ (212)	$ (75)
Other Expenses	126	111	256	200
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service credit	5	3	9	7
Amortization of actuarial loss	(4)	(2)	(7)	(4)
Net settlement loss	(2)	(3)	(6)	(17)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	(1)	0	(1)
Income from operations before income taxes	(1)	(3)	(4)	(15)
Provision for income taxes	0	0	0	0
Total reclassifications to expense, net of tax	(1)	(3)	(4)	(15)
Other Expenses	(4)	0	(4)	0
Net recognized loss in discontinued operations, net of tax	0	0	0	(30)
Total reclassifications to expense	$ (5)	$ (3)	$ (8)	$ (45)