Summary Of Changes In SARs Outstanding (Detail) (USD $)	3 Months Ended
	Mar. 31, 2012 Year
Weighted Average Remaining Contractual Term
Granted	1.6
Stock Appreciation Rights
SARs
Beginning Balance	2,500,000
Granted	400,000
Forfeited
Exercised	(400,000)
Ending Balance	2,500,000	[1],[2]
Vested and exercisable at March 31, 2012	1,400,000	[1]
Per Share Weighted Average Exercise Price
Beginning Balance	20.39
Granted	37.81
Forfeited
Exercised	19.28
Ending Balance	23.20	[1],[2]
Vested and exercisable at March 31, 2012	18.36	[1]
Per Share Weighted Average Grant Date Fair Value
Beginning Balance	7.66
Granted	12.99
Forfeited
Exercised	7.26
Ending Balance	8.53	[1],[2]
Vested and exercisable at March 31, 2012	6.91	[1]
Weighted Average Remaining Contractual Term
Beginning Balance	4
Granted	6.90
Forfeited
Exercised
Ending Balance	4.38	[1],[2]
Vested and exercisable at March 31, 2012	3.35	[1]

[1] Total SARs outstanding had an intrinsic value of $48.9 million. SARs vested and exercisable had an intrinsic value of $32.9 million.

[2] As of March 31, 2012, 1.2 million of the SARs outstanding were unvested. The Company expects that substantially all of these unvested awards will vest in future periods.