Stock-Based Compensation (Summary Of Stock Appreciation Rights Activity) (Detail) (Stock Appreciation Rights [Member], USD $)	6 Months Ended
	Jun. 30, 2012
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding	262,800
Number of Shares, Granted	193,700
Number of Shares, Forfeited	(14,700)
Number of Shares, Outstanding	441,800
Weighted Average Exercise Price,Outstanding at December 31, 2011	$ 48.79
Weighted Average Exercise Price, Granted	$ 46.39
Weighted Average Exercise Price, Forfeited	$ 46.39
Weighted Average Exercise Price, Outstanding at June 30, 2012	$ 47.81
Weighted Average Remaining Contractual Term (in years), Outstanding at June 30, 2012	9 years 5 months 23 days
Aggregate Intrinsic Value, Outstanding at June 30, 2012	$ 19.3	[1]
Closing stock price of common stock	$ 91.40

[1] The aggregate intrinsic value is calculated as the pre-tax difference between the exercise price of the underlying awards and the closing stock price per share of $91.40 of the Company's common stock on June 29, 2012. The amount is presented in millions.