Divestiture Transactions and Discontinued Operations Divestiture Transactions and Discontinued operations (Components of Discontinued Operations in Consolidated Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
Operating revenues		$ 0		$ 0
Operating benefits (expenses)		(1)		2
Operating income (loss) before income tax		(1)		2
Income tax benefit		1		50
Income from Discontinued Operations, Net of Taxes	$ 0	$ 0	$ 0	$ 52