Equity Equity (Common Stock) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Jun. 28, 2017	Dec. 31, 2016	Jul. 19, 2016	Dec. 31, 2015
Equity [Abstract]
Common Stock, Shares, Issued	485,707,644	482,790,696	480,136,039
Stock Issued During Period, Value, New Issues	4,175,909	2,916,948	2,654,657
Common Stock, Shares, Issued	485,707,644	482,790,696	480,136,039	489,883,553		485,707,644		482,790,696
Treasury Stock, Shares	(18,707,338)	(810,585)	(41,148)
Treasury Stock, Shares, Acquired	(34,122,279)	(17,896,753)	(769,437)
Treasury Stock, Shares	(52,829,617)	(18,707,338)	(810,585)
Common Stock, Shares, Issued	489,883,553	485,707,644	482,790,696
Stock Repurchase Program, Authorized Amount					$ 760		$ 700
Common Stock, Shares, Outstanding				437,053,936		467,000,306		481,980,111