Income per Share (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted Average Number of Shares Outstanding, Basic	870	861	853
Weighted Average Number Diluted Shares Outstanding Adjustment	0	0	0
Weighted Average Number of Shares Outstanding, Diluted	870	861	853
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially Dilutive Securities During Period	6	11	10
Ordinarily Dilutive Shares	2	1	2
Antidilutive securities excluded from the computation of diluted income per share (shares)	8	12	12