Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ (168)	$ (34)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial loss	(3)	(2)
Net settlement loss	(4)	(14)
Income from operations before income taxes	(7)	(16)
Provision for income taxes	0	0
Total reclassifications to expense, net of tax	(7)	(16)
Net recognized loss in discontinued operations, net of tax	0	(30)
Total reclassifications to expense	$ (7)	$ (46)