Condensed Consolidated Statements of Shareholders' Equity (Unaudited) (Parentheticals)	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Common Stock [Member] | Common Class B [Member]
Shares of treasury stock purchased (in shares)	3,677
Shares of common stock issued for the exercise of stock options (in shares)	9,296
Settlement of class B common shares in connection with recapitalization, shares exchanged (in shares)	3,527,246
Retirement of class B common shares in connection with recapitalization, shares retired | $	$ 4,328,552
Dividends declared per common share (in dollars per share) | $ / shares	$ 0.60
Common Stock [Member]
Shares of treasury stock purchased (in shares)	156,797
Shares of common stock issued for the exercise of stock options (in shares)	344,958
Issuance of restricted common shares, net of forfeitures (in shares)	3,496
Settlement of restricted common shares and stock options in connection with recapitalization, shares (in shares)	90,369
Settlement of class B common shares in connection with recapitalization, shares issued (in shares)	3,527,246
Dividends declared per common share (in dollars per share) | $ / shares	$ 0.27
Shares of common stock issued for the exercise of stock options (in shares)	276,716