Stock-Based Compensation Expense Recognized In Consolidated Statements Of Operations (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Component of Operating Other Cost and Expense [Line Items]
Stock-based compensation expense	$ 7,900	[1]	$ 7,800	[1]	$ 18,802	[1]	$ 16,993	[1]
Retirement Eligible Employees, Equity Award
Component of Operating Other Cost and Expense [Line Items]
Stock-based compensation expense	$ 200		$ 300		$ 3,200		$ 2,800

[1] The three months ended June 30, 2012 and 2011 includes charges of $0.2 million and $0.3 million, respectively, related to awards to retirement-eligible employees, since a portion of the awards granted to retirement-eligible employees vest immediately. The six months ended June 30, 2012 and 2011 includes charges of $3.2 million and $2.8 million, respectively, for retirement-eligible employees.