Stock Based Compensation - Outstanding Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding shares, beginning of year	5,306,506	6,002,174	5,640,619
Exercised, shares	(704,242)	(489,324)	(2,894)
Forfeited	(55,710)	(124,710)	(177,321)
Cancelled, shares	(49,481)	(346,634)	(14,730)
Outstanding shares, end of year	5,879,573	5,306,506	6,002,174
Outstanding Weighted Average Exercise Price, beginning of year balance	$ 42.69	$ 40.72	$ 41.53
Exercised, Weighted Average Exercise Price	$ 18.47	$ 18.47	$ 23.69
Forfeited	$ 27.46	$ 32.20	$ 32.62
Cancelled, Weighted Average Exercise Price	$ 44.75	$ 33.87	$ 44.94
Outstanding Weighted Average Exercise Price, end of year	$ 41.29	$ 42.69	$ 40.72
Options At Fair Market Value [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted - above fair market value, shares	1,382,500	265,000	376,500
Granted - above fair market value, Weighted Average Exercise Price	$ 25.33	$ 25.07	$ 29.37
Options Above Fair Market Value [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted - above fair market value, shares			180,000
Granted - above fair market value, Weighted Average Exercise Price			$ 31.75