Equity And Stock-Based Compensation (Schedule Of Stock Options Outstanding And Exercisable) (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2014
Equity And Stock-Based Compensation [Line Items]
Weighted Average Exercise Price of Options Outstanding, Granted			$ 13.42	$ 7.40
Class A [Member]
Equity And Stock-Based Compensation [Line Items]
Common Stock Options Outstanding, Beginning balance	532,750	568,250	568,250
Common Stock Options Outstanding, Granted	100,000	12,000	112,000	20,000
Common Stock Options Outstanding, Exercised	(89,500)	(47,500)	(222,100)
Common Stock Options Outstanding, Forfeited	(4,000)
Common Stock Options Outstanding, Ending balance	539,250	532,750	539,250
Weighted Average Exercise Price of Options Outstanding, Beginning price	$ 7.01	$ 6.88	$ 6.88
Weighted Average Exercise Price of Options Outstanding, Granted	13.42	12.34
Weighted Average Exercise Price of Options Outstanding, Exercised	5.29	6.87
Weighted Average Exercise Price of Options Outstanding, Forfeited	6.23
Weighted Average Exercise Price of Options Outstanding, Ending price	$ 8.49	$ 7.01	$ 8.49
Common Stock Exercisable Options, Outstanding Beginning balance	313,750	348,000	348,000
Common Stock Exercisable Options Outstanding, Granted	31,250	13,250
Common Stock Exercisable Options Outstanding, Exercised	(89,500)	(47,500)
Common Stock Exercisable Options Outstanding, Forfeited	(3,000)
Common Stock Exercisable Options, Outstanding Ending balance	252,500	313,750	252,500
Weighted Average Price of Exercisable Options, Outstanding Beginning balance	$ 7.02	$ 6.82	$ 6.82
Weighted Average Price of Exercisable Options, Outstanding Ending balance	$ 7.56	$ 7.02	$ 7.56
Class B [Member]
Equity And Stock-Based Compensation [Line Items]
Common Stock Options Outstanding, Beginning balance	185,100	185,100	185,100
Common Stock Options Outstanding, Exercised	(85,100)
Common Stock Options Outstanding, Ending balance	100,000	185,100	100,000
Weighted Average Exercise Price of Options Outstanding, Beginning price	$ 9.90	$ 9.90	$ 9.90
Weighted Average Exercise Price of Options Outstanding, Granted
Weighted Average Exercise Price of Options Outstanding, Exercised	$ 9.51
Weighted Average Exercise Price of Options Outstanding, Forfeited
Weighted Average Exercise Price of Options Outstanding, Ending price	$ 10.24	$ 9.90	$ 10.24
Common Stock Exercisable Options, Outstanding Beginning balance	185,100	185,100	185,100
Common Stock Exercisable Options Outstanding, Granted
Common Stock Exercisable Options Outstanding, Exercised	(85,100)
Common Stock Exercisable Options Outstanding, Forfeited
Common Stock Exercisable Options, Outstanding Ending balance	100,000	185,100	100,000
Weighted Average Price of Exercisable Options, Outstanding Beginning balance	$ 9.90	$ 9.90	$ 9.90
Weighted Average Price of Exercisable Options, Outstanding Ending balance	$ 10.24	$ 9.90	$ 10.24