Stock-Based Compensation Expense by Award Type (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 32,865,000	[1]	$ 32,634,000	[1]	$ 26,066,000	[1]
Stock Appreciation Rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	4,400,000		4,600,000		4,400,000
Common Stock Equivalents
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	500,000		500,000		400,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 28,000,000		$ 27,500,000		$ 21,300,000

[1] Includes charges of $3.1 million in both 2011 and 2010 and $1.9 million in 2009 for awards to retirement-eligible employees.