Earnings Per Share (Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	$ 39,240	$ 42,111	$ 121,988	$ 113,892
Loss from discontinued operations, net of tax		(147)		(404)
Net income	39,240	41,964	121,988	113,488
Income from continuing operations, basic	$ 0.38	$ 0.38	$ 1.14	$ 1.01
Loss from discontinued operations, net of tax, basic
Net income	$ 0.38	$ 0.38	$ 1.14	$ 1.01
Income from continuing operations, diluted	$ 0.37	$ 0.38	$ 1.14	$ 1.00
Loss from discontinued operations, net of tax, diluted
Net income	$ 0.37	$ 0.38	$ 1.14	$ 1.00
Basic [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	39,240	42,111	121,988	113,892
Loss from discontinued operations, net of tax		(147)		(404)
Net income	39,240	41,964	121,988	113,488
Weighted average common shares outstanding	104,254	110,160	106,624	112,814
Income from continuing operations, basic	$ 0.38	$ 0.38	$ 1.14	$ 1.01
Loss from discontinued operations, net of tax, basic
Net income	$ 0.38	$ 0.38	$ 1.14	$ 1.01
Diluted [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	39,240	42,111	121,988	113,892
Loss from discontinued operations, net of tax		(147)		(404)
Net income	$ 39,240	$ 41,964	$ 121,988	$ 113,488
Weighted average shares and assumed conversions	105,020	111,063	107,414	113,744
Income from continuing operations, diluted	$ 0.37	$ 0.38	$ 1.14	$ 1.00
Loss from discontinued operations, net of tax, diluted
Net income	$ 0.37	$ 0.38	$ 1.14	$ 1.00
Stock Options [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	550	711	621	773
Restricted Stock-Based Compensation [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	216	192	169	157