Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets
First preferred shares, no par value
First preferred shares, shares issued	0	0
First preferred shares, shares outstanding	0	0
Common shares, no par value
Common shares, shares issued	258,624,486	258,511,236
Common shares, shares outstanding	258,624,486	258,511,236