Consolidated Statements of Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Interest income	$ 1	$ 0	$ 3	$ 2
Tax (benefit) expense on gain (loss) of dispositions from discontinued operations	$ 0	$ 0	$ 0	$ (1)