Total Stock-Based Compensation Expense (Detail) (USD $) In Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010		Jun. 30, 2011	Jun. 30, 2010
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share based compensation expense, net for tax	$ 4,909	$ 3,109	[1]	$ 10,524	$ 6,219	[1]
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share based compensation expense, net for tax	1,062	439	[1]	1,870	745	[1]
Restricted Stock and Restricted Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share based compensation expense, net for tax	3,466	1,811	[1]	8,151	3,632	[1]
Performance Shares and Deferred Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share based compensation expense, net for tax	$ 381	$ 859	[1]	$ 503	$ 1,842	[1]

[1] Unrealized tax benefits for the three-month and six-month periods ended June 30, 2010 was $1.2 million and $2.6 million, respectively.