Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Allowance for accounts receivable	$ 560	$ 664
Accumulated amortization on other intangibles, deferred costs and investments	$ 12,031	$ 11,336
Preferred Stock, Shares Authorized	1,500	1,500
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Treasury stock, shares (in shares)	1,625	1,612
Common Class A [Member]
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	35,000	35,000
Common Stock, Shares, Issued	6,638	6,603
Common Class B [Member]
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	3,500	3,500
Common Stock, Shares, Issued	878	865
Common Stock, Shares, Outstanding	878	865