Stock-Based Compensation Expense Recognized In Consolidated Statements Of Operations (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Component of Operating Other Cost and Expense [Line Items]
Stock-based compensation expense	$ 10,939	[1]	$ 9,162	[1]
Retirement Eligible Employees, Equity Award
Component of Operating Other Cost and Expense [Line Items]
Stock-based compensation expense	$ 3,000		$ 2,500

[1] Includes charges of $3.0 million and $2.5 million for the three months ended March 31, 2012 and 2011 respectively, related to awards to retirement-eligible employees, since a portion of the awards vest immediately.