Income per Share (Details) - shares
shares in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]

Earnings Per Share [Text Block]

Income per Share

Basic income or loss per share is based on the weighted average number of common shares outstanding during the period. Diluted income per share includes additional common shares that would have been outstanding if potential common shares with a dilutive effect had been issued. Antidilutive securities represent potentially dilutive securities which are excluded from the computation of diluted income or loss per share as their impact was antidilutive.

A reconciliation of the number of shares used for the basic and diluted income per share computations is as follows:

	Year Ended December 31
Millions of shares	2015	2014	2013
Basic weighted average common shares outstanding	853	848	898
Dilutive effect of awards granted under our stock incentive plans	—	4	4
Diluted weighted average common shares outstanding	853	852	902
Antidilutive shares:
Options with exercise price greater than the average market price	10	2	3
Options which ordinarily would be considered dilutive if not for being in net loss position	2	—	—
Total antidilutive shares	12	2	3

Ordinarily Dilutive Shares

2

0

0

Weighted Average Number of Shares Outstanding, Basic

853

848

898

Weighted Average Number Diluted Shares Outstanding Adjustment

0

4

4

Weighted Average Number of Shares Outstanding, Diluted

853

852

902

Stock Options

Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]

Antidilutive securities excluded from the computation of diluted income per share (shares)

12

2

3

Potentially Dilutive Securities During Period

10