CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Receivables, allowances	$ 1	$ 1
Property and equipment, accumulated depreciation	$ 3,319	$ 3,306
Common shares, par value	$ 1.25	$ 1.25
Common shares, authorized	1,360,000,000	1,360,000,000
Common shares, issued	752,711,155	748,528,131
Common shares, outstanding	752,711,155	748,528,131