Stockholders' Equity (Schedule Of Stock Options) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Option Shares, Exercised	550,352		151,150	113,223
Number of Option Shares, Outstanding	1,320,819	[1]
Number of Options Shares, Exercisable at December 31, 2012	690,629	[1]
Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Option Shares, Outstanding	1,810,650		1,996,490	1,759,940
Number of Option Shares, Granted			345,000	469,250
Number of Option Shares, Exercised	(422,131)		(87,300)	(81,000)
Number of Option Shares, Forfeited	(67,700)		(100,900)	(151,700)
Number of Option Shares, Expired			(342,640)
Number of Option Shares, Outstanding	1,320,819		1,810,650	1,996,490	1,759,940
Number of Options Shares, Exercisable at December 31, 2012	690,629
Stock Option Exercise Price, Outstanding, Minimum	$ 8.09		$ 10.09	$ 10.09	$ 11.59
Stock Option Exercise Price, Outstanding, Maximum	$ 29.11		$ 31.11	$ 31.11	$ 32.61
Stock Option Exercise Price, Granted			$ 23.17	$ 21.17
Stock Option Exercise Price, Exercised, Minimum	$ 8.09		$ 10.09	$ 11.59
Stock Option Exercise Price, Exercised, Maximum	$ 31.11		$ 19.67	$ 20.99
Stock Option Exercise Price, Forfeited, Minimum	$ 10.09		$ 10.09	$ 11.59
Stock Option Exercise Price, Forfeited, Maximum	$ 31.11		$ 31.11	$ 32.61
Stock Option Exercise Price, Modification for cash dividend, Minimum				$ 10.09
Stock Option Exercise Price, Modification for cash dividend, Maximum				$ 31.11
Stock Option Exercise Price, Expired, Minimum			$ 26.83
Stock Option Exercise Price, Expired, Maximum			$ 27.21
Stock Option Exercise Price, Reduction For Cash Dividend, Minimum	$ 8.09
Stock Option Exercise Price, Reduction For Cash Dividend, Maximum	$ 29.11
Stock Option Exercise Price, Exercisable, Minimum	$ 8.09
Stock Option Exercise Price, Exercisable, Maximum	$ 29.11
Weighted Average Exercise Price, Outstanding	$ 21.46		$ 21.70	$ 23.46
Weighted Average Exercise Price, Granted			$ 23.17	$ 21.17
Weighted Average Exercise Price, Exercised	$ 19.13		$ 11.39	$ 14.03
Weighted Average Exercise Price, Forfeited	$ 22.61		$ 22.37	$ 24.86
Weighted Average Exercise Price, Modification for cash dividend				$ (1.50)
Weighted Average Exercise Price, Expired			$ 26.87
Weighted Average Exercise Price, Reduction For Cash Dividend	$ (2.00)
Weighted Average Exercise Price, Outstanding	$ 19.92		$ 21.46	$ 21.70	$ 23.46
Weighted Average Exercise Price, Exercisable	$ 21.59

[1] The aggregate intrinsic value for option shares outstanding and option shares exercisable is $16.3 million and $7.4 million, respectively. The weighted average remaining term for option shares outstanding and option shares exercisable is 3.0 years and 2.1 years, respectively