Stockholders' Equity - Earnings per Share (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity [Abstract]
As reported shares (in shares)	1,003	968	998	940
Effect of options and performance share award units (in shares)	7	7	7	5
Diluted shares (in shares)	1,010	975	1,005	945
Stock options and performance share award units that were not included in the diluted earnings per share calculation (in shares)	0	0	0	0