Stockholders' Equity (Schedule Of Stock Options) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Option Shares, Exercised	(476,047)		(681,426)	(550,352)
Number of Option Shares, Outstanding	453,331	[1]
Number of Options Shares, Exercisable at December 31, 2014	289,971	[1]
Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Option Shares, Outstanding	723,661		1,320,819	1,810,650
Number of Option Shares, Exercised	(258,530)		(574,288)	(422,131)
Number of Option Shares, Forfeited	(11,800)		(22,870)	(67,700)
Number of Option Shares, Reduction for cash dividend			0	0
Number of Option Shares, Outstanding	453,331		723,661	1,320,819	1,810,650
Number of Options Shares, Exercisable at December 31, 2014	289,971
Stock Option Exercise Price, Outstanding, Minimum	$ 15.49		$ 6.09	$ 8.09	$ 10.09
Stock Option Exercise Price, Outstanding, Maximum	$ 19.17		$ 19.17	$ 29.11	$ 31.11
Stock Option Exercise Price, Exercised, Minimum	$ 6.09		$ 8.09	$ 8.09
Stock Option Exercise Price, Exercised, Maximum	$ 19.17		$ 29.11	$ 31.11
Stock Option Exercise Price, Forfeited, Minimum	$ 6.09		$ 8.09	$ 10.09
Stock Option Exercise Price, Forfeited, Maximum	$ 19.17		$ 29.11	$ 31.11
Stock Option Exercise Price, Reduction For Cash Dividend, Minimum			$ 6.09	$ 8.09
Stock Option Exercise Price, Reduction For Cash Dividend, Maximum			$ 19.17	$ 29.11
Stock Option Exercise Price, Exercisable, Minimum	$ 15.49
Stock Option Exercise Price, Exercisable, Maximum	$ 19.17
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Outstanding	$ 15.46		$ 19.92	$ 21.46
Weighted Average Exercise Price, Exercised	$ 12.89		$ 23.04	$ 19.13
Weighted Average Exercise Price, Forfeited	$ 16.93		$ 19.36	$ 22.61
Weighted Average Exercise Price, Reduction For Cash Dividend			$ (2.00)	$ (2.00)
Weighted Average Exercise Price, Outstanding	$ 16.89		$ 15.46	$ 19.92	$ 21.46
Weighted Average Exercise Price, Exercisable	$ 16.27

[1] The aggregate intrinsic value for option shares outstanding and option shares exercisable is $15.5 million and $10.1 million, respectively. The weighted average remaining term for option shares outstanding and option shares exercisable is 2.0 years and 1.8 years, respectively.