Earnings Per share - Schedule of Computation for Earnings Per Share Types (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income	$ 1,485	$ 801	$ 2,231	$ 1,014
Basic weighted average shares outstanding	803	841	811	843
Dilutive effect of share-based awards	8	9	8	9
Diluted weighted average shares outstanding	811	850	819	852
Basic Earnings Per Share	$ 1.85	$ 0.95	$ 2.75	$ 1.20
Diluted Earnings Per Share	$ 1.83	$ 0.94	$ 2.72	$ 1.19