CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Tax expense (benefit) of actuarial gains (losses)	$ 24	$ 17	$ 50	$ 25
Tax expense (benefit) of prior service credits (costs)	$ (1)	$ (1)	$ (1)	$ 0