Stockholders' Equity - Earnings per Share (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity [Abstract]
As reported shares	968	910	940	910
Effect of options and performance share award units	7	2	5	3
Diluted shares	975	912	945	913
Stock options and performance share award units that were not included in the diluted earnings per share calculation (in shares)	0	15	0	1