Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Shareholders' Equity
Common shares, issued (in shares)	262,304,249	240,440,830
Common shares, outstanding (in shares)	262,304,249	240,440,830
Exchangeable shares, issued (in shares)	16,323,819	17,681,123
Exchangeable shares, outstanding (in shares)	16,323,819	17,681,123
Common shares, par value (in dollars per share)	$ 0.001	$ 0.001