Stock-Based Compensation and Stock Repurchases (Schedule Of Stock Options Outstanding And Exercisable) (Details) - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Equity And Stock-Based Compensation [Line Items]
Weighted Average Exercise Price of Options Outstanding, Granted	$ 15.97	$ 11.83
Class A [Member]
Equity And Stock-Based Compensation [Line Items]
Common Stock Options Outstanding, Beginning balance	535,077	486,565	486,565
Common Stock Options Outstanding, Granted	149,841		169,327
Common Stock Options Outstanding, Exercised	(10,500)		(46,815)
Common Stock Options Outstanding, Forfeited	(2,500)		(74,000)
Common Stock Options Outstanding, Ending balance	671,918		535,077	486,565
Weighted Average Exercise Price of Options Outstanding, Beginning price	$ 9.84	$ 8.68	$ 8.68
Weighted Average Exercise Price of Options Outstanding, Granted	15.97		11.87
Weighted Average Exercise Price of Options Outstanding, Exercised	8.25		9.50
Weighted Average Exercise Price of Options Outstanding, Forfeited	6.23		7.02
Weighted Average Exercise Price of Options Outstanding, Ending price	$ 11.25		$ 9.84	$ 8.68
Common Stock Exercisable Options, Outstanding Beginning balance	3,615,191	2,188,011	2,188,011
Common Stock Exercisable Options Outstanding, Exercised	91,020		220,002
Common Stock Exercisable Options, Outstanding Ending balance	3,608,972		3,615,191	2,188,011
Weighted average remaining years of contractual life	1 year 10 months 17 days		2 years 7 months 10 days	2 years 10 months 21 days