Stock-Based Compensation Plans (Summary Of Stock Option Activity Under All Plans) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Shares	50	[1]	41	[1]
Aggregate intrinsic value of stock options outstanding	$ 10,824
Aggregate intrinsic value of stock options exercisable	9,880
Aggregate intrinsic values of stock options expected to vest	$ 10,772
Weighted average remaining contractual lives of stock options outstanding, years	4 years
Weighted average remaining contractual lives of stock options exercisable, years	3 years 7 months 6 days
Weighted average remaining contractual lives of stock options expected to vest, years	4 years
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning of period, Shares	1,501		2,068
Granted, Shares	29		25
Exercised, Shares	(776)		(545)
Expired, Shares			(10)
Options outstanding, end of period, Shares	754	[2]	1,538	[2]
Options exercisable, end of period, Shares	686	[2]	1,384	[2]
Options vested and expected to vest, end of period, Shares	751	[2]	1,530	[2]
Weighted average fair value of options granted during the period	$ 15.18		13.18
Options outstanding, beginning of period, Exercise Price	$ 31		31
Granted, Exercise Price	$ 44		37
Exercised, Exercise Price	$ 30		29
Expired, Exercise Price			39
Options outstanding, end of period, Exercise Price	$ 34	[2]	31	[2]
Options exercisable, end of period, Exercise Price	$ 34	[2]	33	[2]
Options vested and expected to vest, end of period, Exercise Price	$ 34	[2]	31	[2]

[1] The total value of the restricted share grants for the nine months ended September 30, 2012 and 2011 was $2,184 and $1,532, respectively.

[2] At September 30, 2012, the aggregate intrinsic value of stock options outstanding, exercisable and vested/expected to vest was $10,824, $9,880 and $10,772, respectively. At that same date, the weighted average remaining contractual lives of stock options outstanding, exercisable and vested/expected to vest was 4.0 years, 3.6 years and 4.0 years, respectively.