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
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average common shares outstanding for basic and diluted loss per share		430	439	437	438
Anti-dilutive shares excluded from diluted loss per share (1)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from diluted loss per share (1)	[1]	1	1	1	2
Future potentially dilutive shares excluded from diluted loss per share (2)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Earnings Per Share, Potentially Dilutive Securities	[2]	3	3	5	3

[1] The calculation of diluted loss per share for both the three and nine months ended September 30, 2016 excludes shares potentially issuable under stock-based incentive compensation plans and the employee stock purchase plan, as their effect, if included, would have been anti-dilutive.

[2] Options where the exercise price exceeds the average market price are excluded from the calculation of diluted net loss or earnings per share because their effect would be anti-dilutive.