Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Reclassification of losses to net benefit cost, income tax	$ 2	$ 2	$ 4	$ 4
Net derivative instruments gain arising during the period, income tax (benefit) expense	(7)	16	(23)	17
Reclassification of realized derivative instruments (gain) loss to net income, income tax (less than)	$ 1	$ 1	$ 1	$ 1