Stock Compensation (Summary Of Stock Option Activity) (Details) - Stock Options [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, Beginning Balance, Shares	1,911,000	1,896,000	2,021,000
Granted, Shares	260,000	387,000	328,000
Exercised, Shares	(394,000)	(372,000)	(248,000)
Forfeited, Shares	(31,000)		(112,000)
Expired, Shares	(5,000)		(93,000)
Outstanding, Ending Balance, Shares	1,741,000	1,911,000	1,896,000	2,021,000
Vested and expected to vest, Shares	1,741,000
Exercisable, Shares	1,167,000
Outstanding, Beginning Balance, Weighted Average Exercise Price	$ 8.59	$ 7.65	$ 7.43
Granted, Weighted Average Exercise Price	16.30	10.34	10.83
Exercised, Weighted Average Exercise Price	6.30	5.60	7.42
Forfeited, Weighted Average Exercise Price	12.47		9.93
Expired, Weighted Average Exercise Price	7.01		12.08
Outstanding, Ending Balance, Weighted Average Exercise Price	10.19	$ 8.59	$ 7.65	$ 7.43
Vested and expected to vest, Weighted Average Exercise Price	10.19
Exercisable, Weighted Average Exercise Price	$ 8.81
Outstanding, Weighted Average Remaining Contractual Term in years	3 years 7 months 21 days	3 years 6 months 18 days	3 years 3 months 22 days	3 years 6 months 15 days
Vested and expected to vest, Weighted Average Remaining Contractual Term in Years	3 years 7 months 21 days
Exercisable, Weighted Average Remaining Contractual Term in years	2 years 9 months 4 days
Outstanding, Aggregate Intrinsic Value	$ 15,598,000	$ 20,179,000	$ 5,992,000	$ 8,021,000
Vested and expected to vest, Aggregate Intrinsic Value	15,598,000
Exercisable, Aggregate Intrinsic Value	$ 12,057,000