CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Receivables, allowances	$ 4	$ 3
Property and equipment, accumulated depreciation	$ 6,371	$ 6,294
Common shares, par value	$ 1.25	$ 1.25
Common shares, authorized	1,360,000,000	1,360,000,000
Common shares, issued	759,044,221	510,483,285
Common shares, outstanding	759,044,221	510,483,285
6.375 percent Mandatory Convertible Preference Shares, Series A
Preference shares, par value	$ 1.00	$ 1.00
Preference shares, liquidation	$ 50.00	$ 50.00
Preference shares, authorized	40,000,000	40,000,000
Preference shares, issued	13,799,711	13,799,711
Preference shares, outstanding	13,799,711	13,799,711