Capital Stock - Summary of Stock Options Issued Under Stock Option Plans (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, beginning of year, Shares	6,092
Granted, Shares	2,072
Exercised, Shares	(311)
Forfeited or expired, Shares	(280)
Outstanding, end of year, Shares	7,573	6,092
Expected to vest, Shares	2,900
Exercisable, end of year, Shares	3,922
Available for grant, end of year	15,498
Weighted average fair value of options granted during the year	$ 26.41	$ 42.20	$ 34.12
Outstanding, beginning of year, Weighted Average exercise Price	$ 91.96
Granted, Weighted Average Exercise Price	$ 82.65
Exercised, Weighted Average Exercise Price	$ 56.15
Forfeited or expired, Weighted Average Exercise Price	$ 102.90
Outstanding, end of year, Weighted Average Exercise Price	$ 90.47	$ 91.96
Expected to vest, Weighted Average Exercise Price	$ 96.23
Exercisable, end of year, Weighted Average Exercise Price	$ 85.55