Income per Share Income per Share (Tables)

12 Months Ended

Dec. 31, 2017

Weighted average shares outstanding and antidilutive shares [Line Items]

Weighted average shares outstanding and antidilutive shares [Table Text Block]

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	2017	2016	2015
Basic weighted average common shares outstanding	870	861	853
Dilutive effect of awards granted under our stock incentive plans	—	—	—
Diluted weighted average common shares outstanding	870	861	853
Antidilutive shares:
Options with exercise price greater than the average market price	6	11	10
Options which are antidilutive due to net loss position	2	1	2
Total antidilutive shares	8	12	12