Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Class A Voting [Member]
Shareholders' equity:
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	3,000,000	3,000,000
Common stock, shares outstanding (in shares)	2,608,819	2,615,339
Class B Non-voting [Member]
Shareholders' equity:
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, shares outstanding (in shares)	11,738,578	12,253,922