Consolidated Statements of Financial Position (Parenthetical) (Parentheticals) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Allowance for doubtful accounts	$ 62	$ 162
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	172,351,680	169,247,282
Common stock, shares outstanding	172,351,680	169,247,282