Stock-Based Compensation - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended			3 Months Ended
	Mar. 31, 2012 Year	Dec. 31, 2011	Mar. 31, 2012 2003 Long-Term Incentive Plan	Mar. 31, 2012 Stock Appreciation Rights Year	Mar. 31, 2012 Restricted Stock Units	Mar. 31, 2012 Restricted Stock Units Service Based Awards Year	Mar. 31, 2012 Restricted Stock Units Performance Based Awards	Mar. 31, 2012 Common Stock Equivalents	Mar. 31, 2012 Employee Stock Option	Mar. 31, 2011 Employee Stock Option	Mar. 31, 2012 Employee Stock Purchase Plan	Mar. 31, 2011 Employee Stock Purchase Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Common stock available for stock-based compensation awards			6.0
Common stock available for stock-based compensation awards, par value	$ 0.0005	$ 0.0005	$ 0.0005
Total unrecognized stock-based compensation cost	$ 62,700,000
Total unrecognized stock-based compensation cost, period to be recognized	2.7			4		4
Vest ratably over				4 years		4 years	4 years
Expiration date				7 years
Share entitlement description					each RSU that vests entitles the awardee to one common share			each CSE entitles the holder to one common share
Directors' fees payable, percentage Board of Directors members can opt to receive in cash								50.00%
Cash received from option exercises									4,400,000	13,100,000
Percentage of employee's compensation, eligible employees may not exceed, when purchasing Common Stock through payroll deductions											10.00%
Amount of employee's compensation, eligible employees may not exceed, when purchasing Common Stock through payroll deductions											23,750
Price equals to closing price of Common Stock, percentage											95.00%
Shares available for purchase											1.3
Cash received from share purchases											$ 1,100,000	$ 1,000,000