Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net actuarial gains (losses) of defined benefit plans:
Adjustment, net of tax benefit (expense)	$ 25	$ (60)	$ 29
Recognized within Net income, net of tax benefit (expense)	(21)	(37)	(104)
Prior service cost of defined benefit plans:
Adjustment, net of tax benefit (expense)	0	1	1
Recognized within Net income, net of tax benefit (expense)	0	2	0
Derivative instruments:
Change in fair value, net of tax benefit (expense)	0	0	1
Recognized within Net income, net of tax benefit (expense)	(1)	(1)	0
Available-for-sale investments:
Unrealized gains (losses), net of tax benefit (expense)	$ 0	$ 0	$ (1)