CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Tax expense (benefit) of actuarial gains (losses)	$ 25	$ (91)	$ 75	$ (58)
Tax expense (benefit) of prior service costs	$ (1)	$ (13)	$ 0	$ (43)