Earnings Per Share - (Details) - shares shares in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average common shares outstanding for basic and diluted loss per share		442	437
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]	0	2
Future potentially dilutive shares excluded from diluted loss per share (2)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from diluted loss per share (1)	[2]	7	3

[1] The calculation of diluted loss per share for the three months ended March 31, 2016 and 2015 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.