Summary Of Changes In SARs Outstanding (Detail) (USD $)	6 Months Ended
	Jun. 30, 2012 Year
Weighted Average Remaining Contractual Term
Granted	1.4
Stock Appreciation Rights
SARs
Beginning Balance	2,500,000
Granted	400,000
Forfeited
Exercised	(500,000)
Ending Balance	2,400,000	[1],[2]
Vested and exercisable at June 30, 2012	1,300,000	[2]
Per Share Weighted Average Exercise Price
Beginning Balance	20.39
Granted	37.81
Forfeited
Exercised	18.68
Ending Balance	23.45	[1],[2]
Vested and exercisable at June 30, 2012	18.50	[2]
Per Share Weighted Average Grant Date Fair Value
Beginning Balance	7.66
Granted	12.99
Forfeited
Exercised	7.11
Ending Balance	8.60	[1],[2]
Vested and exercisable at June 30, 2012	6.93	[2]
Weighted Average Remaining Contractual Term
Beginning Balance	4
Granted	6.61
Forfeited	0
Exercised	0
Ending Balance	4.20	[1],[2]
Vested and exercisable at June 30, 2012	3.18	[2]

[1] As of June 30, 2012, 1.1 million of the SARs outstanding were unvested. The Company expects that substantially all of these unvested awards will vest in future periods.

[2] As of June 30, 2012, total SARs outstanding had an intrinsic value of $47.5 million. SARs vested and exercisable had an intrinsic value of $31.1 million.