Capital Stock - Common Stock Outstanding (Detail)	0 Months Ended	12 Months Ended
	Jun. 10, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity [Abstract]
Balance, beginning of year		395,772,908	391,640,770	384,117,643
Shares issued for stock-based compensation plans:
Treasury shares issued		17,454	25,214	60,767
Common shares issued		1,665,259	929,596	1,189,693
Common shares issued for conversion of preferred shares			14,399,247
Treasury shares acquired	(32,200,000)	(20,950,729)	(11,221,919)
Cordillera consideration				6,272,667
Balance, end of year		376,504,892	395,772,908	391,640,770