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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
Operating revenues	$ 0	$ 0	$ 0	$ 0
Operating benefits (expenses)	0	0	0	3
Operating income before income tax	0	0	0	3
Income tax benefit	0	52	0	49
Income from Discontinued Operations, Net of Taxes	$ 0	$ 52	$ 0	$ 52