Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Receivables, reserve	$ 60	$ 84
Treasury Stock, Common, Shares	8,405,003	7,515,773
Class A [Member]
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	20,000	20,000
Common stock, shares issued	9,000	9,000
Common stock, shares outstanding	9,000	9,000
Class B [Member]
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	900,000,000	900,000,000
Common stock, shares issued	109,505,456	109,505,456
Common stock, shares outstanding	101,100,453	101,989,683