Stock-Based Compensation (Summary Of Stock-Based Compensation Expense And Related Tax Benefits) (Detail) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1,200,000		$ 1,000,000		$ 3,351,000		$ 2,779,000
Income tax benefit from stock-based compensation	700,000		900,000		1,600,000		5,000,000
Excess tax benefit from stock-based compensation	200,000		500,000		302,000		3,942,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,200,000		1,000,000		3,400,000		2,800,000
Income tax benefit from stock-based compensation	600,000		400,000		1,400,000		2,100,000
Excess tax benefit from stock-based compensation	100,000	[1]	0	[1]	100,000	[1]	1,000,000	[1]
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	0		0		0		0
Income tax benefit from stock-based compensation	100,000		500,000		200,000		2,900,000
Excess tax benefit from stock-based compensation	$ 100,000	[1]	$ 500,000	[1]	$ 200,000	[1]	$ 2,900,000	[1]

[1] Excess tax benefits, which represent cash flows from tax deductions in excess of compensation expense recognized for stock options exercised and vested restricted shares, are classified as financing cash flows in the Company’s condensed unaudited consolidated statements of cash flows.