Stock-Based Compensation (Detail) - Summary Of Changes In SARs Outstanding (Parentheticals) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Intrinsic value, SARs outstanding	45.4
Intrinsic values, SARs vested and exercisable	25.5
Stock Appreciation Rights (SARs) [Member] | Unvested [Member]
Unvested SARs (in Shares)	1,200,000
Stock Appreciation Rights (SARs) [Member]
Unvested SARs (in Shares)	2,100,000	[1],[2]	2,500,000

[1] As of September 30, 2012, 1.2 million of SARs outstanding were unvested. The Company expects that substantially all of these unvested awards will vest in future periods.

[2] As of September 30, 2012, total SARs outstanding had an intrinsic value of $45.4 million. SARs vested and exercisable had an intrinsic value of $25.5 million.