Schedule I Condensed Financial Information Parent Company Statements of Shareholders' Equity Parenthetical (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Financial Statements [Line Items]
Tax on foreign currency translation	$ (46)	$ 0	$ 0
Tax on reclassification adjustment for amounts recognized in income	0	0	0
Defined benefit plans:
Tax on amortization of prior service cost and unrecognized gains and losses included in total benefit cost	36	10	9
Tax on decrease (increase) in net actuarial losses	(135)	34	(54)
Tax on immediate recognition of prior service cost and unrecognized gains and losses due to curtailments, settlements, and divestitures	13	1	1
Tax on prior service cost from plan amendments	0	0	3
Tax on deferred derivative gains (losses)	1	1	0
Tax on reclassification adjustment for amounts recognized in income	(1)	0	(3)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	1	0	0
Parent Company
Condensed Financial Statements [Line Items]
Common Treasury Stock, Shares	8,979,927	3,136,663	5,648,930	6,353,851
Tax on foreign currency translation	(46)	0	0
Tax on reclassification adjustment for amounts recognized in income	0	0	0
Defined benefit plans:
Tax on amortization of prior service cost and unrecognized gains and losses included in total benefit cost	36	9	9
Tax on decrease (increase) in net actuarial losses	129	33	(44)
Tax on immediate recognition of prior service cost and unrecognized gains and losses due to curtailments, settlements, and divestitures	13	1	1
Tax on prior service cost from plan amendments	0	0	3
Tax on deferred derivative gains (losses)	1	1	0
Tax on reclassification adjustment for amounts recognized in income	0	0	(3)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	$ 1	$ 0	$ 0