Earnings Per Common Share (Schedule Of Earnings Per Share Basic And Diluted) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Common Share [Line Items]
Net income	$ 18,431	$ 19,258
Weighted average number of common shares outstanding-basic	40,358	43,877
Effect of dilutive stock options	963	886
Effect of dilutive convertible notes	1,159	676
Effect of dilutive restricted shares	705	500
Weighted average number of common shares outstanding-diluted	43,185	45,939
Earnings per common share-basic	$ 0.46	$ 0.44
Earnings per common share-diluted	$ 0.43	$ 0.42
Antidilutive stock options and restricted shares	2,081	2,017
Conversion price of Convertible Notes, per share	$ 31.25
3 3/4% Senior Subordinated Convertible Notes Due 2012 [Member]
Earnings Per Common Share [Line Items]
Senior subordinated convertible notes, interest percentage	3.75%