Stock-Based Compensation - Summary of Stock Options (Detail) (Stock Options [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Options [Member]
Stock Based Compensation [Line Items]
Outstanding shares, beginning of year	14,255	9,957	8,800
Granted, shares	1,986	6,597	3,901
Exercised, shares	(1,925)	(1,900)	(2,454)
Forfeited or expired, shares	(1,319)	(399)	(290)
Outstanding shares, end of year	12,997	14,255	9,957
Exercisable shares, end of year	5,318	5,176	6,286
Outstanding, Weighted Average Exercise Price, beginning of year	$ 32.91	$ 28.95	$ 25.98
Granted, Weighted Average Exercise Price	$ 34.86	$ 37.04	$ 33.56
Exercised, Weighted Average Exercise Price	$ 26.59	$ 26.46	$ 25.17
Forfeited or expired, Weighted Average Exercise Price	$ 34.71	$ 33.05	$ 32.88
Outstanding, Weighted Average Exercise Price, end of year	$ 33.96	$ 32.91	$ 28.95
Exercisable, Weighted Average Exercise Price, end of year	$ 31.15	$ 27.46	$ 26.25