Total Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation charges	$ 17,825	$ 16,458	$ 12,987
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation charges	3,845	1,724	759
Restricted Stock and Restricted Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation charges	11,939	11,920	4,385
Performance and Deferred Stock Unit
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation charges	$ 2,041	$ 2,814	$ 7,843