Stock Compensation (Summary Of Stock Option Activity) (Details) - Stock Options [Member] - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, Beginning Balance, Shares	1,333,000	1,741,000	1,911,000
Granted, Shares	169,000	219,000	260,000
Exercised, Shares	(334,000)	(578,000)	(394,000)
Forfeited, Shares	(39,000)	(49,000)	(31,000)
Expired, Shares			(5,000)
Outstanding, Ending Balance, Shares	1,129,000	1,333,000	1,741,000	1,911,000
Vested and expected to vest, Shares	1,129,000
Exercisable, Shares	782,000
Outstanding, Beginning Balance, Weighted Average Exercise Price	$ 13.04	$ 10.19	$ 8.59
Granted, Weighted Average Exercise Price	29.62	21.55	16.30
Exercised, Weighted Average Exercise Price	9.87	7.59	6.30
Forfeited, Weighted Average Exercise Price	22.64	14.10	12.47
Expired, Weighted Average Exercise Price			7.01
Outstanding, Ending Balance, Weighted Average Exercise Price	16.14	$ 13.04	$ 10.19	$ 8.59
Vested and expected to vest, Weighted Average Exercise Price	16.14
Exercisable, Weighted Average Exercise Price	$ 12.55
Outstanding, Weighted Average Remaining Contractual Term in years	3 years 8 months 1 day	3 years 11 months 4 days	3 years 7 months 20 days	3 years 6 months 18 days
Vested and expected to vest, Weighted Average Remaining Contractual Term in Years	3 years 8 months 1 day
Exercisable, Weighted Average Remaining Contractual Term in years	2 years 10 months 20 days
Outstanding, Aggregate Intrinsic Value	$ 12,763,000	$ 20,439,000	$ 15,598,000	$ 20,179,000
Vested and expected to vest, Aggregate Intrinsic Value	12,763,000
Exercisable, Aggregate Intrinsic Value	$ 11,371,000