Stock-Based Compensation Plans (Summary Of Stock Option Activity) (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Common Shares, Outstanding at beginning of the period	1,745,427		2,064,534
Common Shares, Granted	219,695		243,116
Common Shares, Exercised	(8,336)		(388,390)
Common Shares, Forfeited or canceled	(6,330)		(14,250)
Common Shares, Outstanding at end of the period	1,950,456		1,905,010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted Average Strike Price, Outstanding at beginning of period	$ 42.31		$ 38.83
Weighted Average Strike Price, Granted	$ 37.85		$ 30.98
Weighted Average Strike Price, Exercised	$ 24.98		$ 19.74
Weighted Average Strike Price, Forfeited or canceled	$ 41.49		$ 33.64
Weighted Average Strike Price, Outstanding at end of period	$ 41.89		$ 41.75
Stock Options, Exercisable	1,437,240		1,407,357
Stock Options, Weighted Average Strike Price, Exercisable	$ 44.64		$ 45.38
Stock Options, Remaining Contractual Term, Outstanding, Years	3 years 3 months 18 days	[1]	3 years 6 months	[1]
Stock Options, Remaining Contractual Term, Exercisable, Years	2 years 3 months 18 days	[1]	2 years 7 months 6 days	[1]
Stock Options, Intrinsic Value, Outstanding	$ 3,975	[2]	$ 4,059	[2]
Stock Options, Intrinsic Value, Exercisable	$ 2,318	[2]	$ 1,889	[2]

[1] Represents the remaining weighted average contractual life in years.

[2] Aggregate intrinsic value represents the total pre-tax intrinsic value (i.e., the difference between the Company’s average of the high and low stock price on the last trading day of the quarter and the option exercise price, multiplied by the number of shares) that would have been received by the option holders if they had exercised their options on the last day of the quarter. Options with exercise prices above the average of the high and low stock price on the last trading day of the quarter are excluded from the calculation of intrinsic value. The intrinsic value will change based on the fair market value of the Company’s stock.