Capital Stock - Common Stock Outstanding (Detail) - shares	12 Months Ended			19 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2014
Equity [Abstract]
Balance, beginning of year (in shares)	378,034,175	376,504,892	395,772,908
Shares issued for stock-based compensation plans:
Treasury shares issued	11,504	17,525	17,454
Common shares issued	1,393,997	1,511,758	1,665,259
Treasury shares acquired	0	0	(20,950,729)	(32,200,000)
Balance, end of year (in shares)	379,439,676	378,034,175	376,504,892	376,504,892