Shared-Based Compensation and Share Repurchases Plans (Tables)

12 Months Ended

Dec. 31, 2017

Shared-Based Compensation and Share Repurchases Plans [Abstract]

Schedule Of Fair Value Of Options, Weighted Average Assumptions

	2017		2016		2015
Stock option exercise price	$	$15.94	$	11.87	$	13.30
Risk-free interest rate		1.66%		1.20%		2.23%
Expected dividend yield		--		--		--
Expected option life in years		3.75		3.75		4.00
Expected volatility		24.95%		25.01%		31.86%
Weighted average fair value	$	3.45	$	2.49	$	3.82

Schedule Of Stock Options Outstanding And Exercisable

	Outstanding Stock Options
	Number of Options		Weighted Average Exercise Price				Weighted Average Remaining Years of Contractual Life	Aggregate Intrinsic Value
	Class A	Class B	Class A		Class B		Class A&B	Class A&B
Outstanding - January 1, 2015	568,250	185,100	$	6.88	$	9.90	2.40	$	4,197,000
Granted	112,000	--		13.30		--
Exercised	(185,685)	(185,100)		6.09		9.90			327,170
Expired	(8,000)	--		6.23		--
Outstanding - December 31, 2015	486,565	--	$	8.68	$	--	2.89	$	2,188,011
Granted	169,327	--		11.87		--
Exercised	(46,815)	--		9.50		--			220,002
Expired	(74,000)	--		7.02		--
Outstanding - December 31, 2016	535,077	--	$	9.84	$	--	2.61	$	3,615,191
Granted	169,762	--		15.94		--
Exercised	(177,750)	--		7.85		--			702,840
Expired	(2,500)	--		6.23		--
Outstanding - December 31, 2017	524,589	--	$	12.50	$	--	3.15	$	3,054,325

Summary Of Vested And Unvested Stock Options

	Vested and Unvested Stock Options
	Number of Options		Weighted Average Exercise Price				Weighted Average Remaining Years of Contractual Life	Aggregate Intrinsic Value
	Class A	Class B	Class A			Class B	Class A&B	Class A&B
Vested
December 31, 2017	186,832	--	$	9.84	$	--	2.30	$	2,202,772
December 31, 2016	296,500	--		7.88		--	1.59		2,584,500
December 31, 2015	256,065	--		7.64		--	2.14		1,401,321
Unvested
December 31, 2017	337,757	--	$	13.86	$	--	3.62	$	851,552
December 31, 2016	238,577	--		12.28		--	3.87		1,030,691
December 31, 2015	230,500	--		9.83		--	3.72		786,690

Schedule Of Restricted Stock Units Issued And Vested

	Number of options			$ value of options
	Granted	Vesting	Unvested	Granted	Vesting	Unvested
2016	68,153	38,062	30,091	815,160	454,966	360,193
2017	70,538	949	69,589	1,124,348	14,880	1,109,467
Total	138,691	39,011	99,680	1,939,507	469,846	1,469,661