Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Common shares, par value (in dollars per share)	$ 0.001	$ 0.001
Common shares, issued	273,442,799	276,072,351
Common shares, outstanding	273,442,799	276,072,351
Exchangeable shares, issued	8,572,066	10,119,745
Exchangeable shares, outstanding	8,572,066	10,119,745