Consolidated Statements of Shareholders' Equity (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Class A [Member]
Shares of treasury stock purchased (in shares)	180,112	87,203	218,344
Shares of common stock issued for the exercise of stock option (in shares)	630,373	227,902	468,318
Issuance of restricted common shares, net of forfeitures (in shares)		6,005	3,496
Settlement of restricted common shares and stock options in connection with recapitalization (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)	$ 0.21	$ 0.78	$ 1.13
Forfeitures of restricted common shares (in shares)	6,793
Common Class B [Member]
Shares of treasury stock purchased (in shares)			3,677
Shares of common stock issued for the exercise of stock option (in shares)			9,296
Cash paid settlement of restricted common shares and stock options in connection with recapitalization			$ 3,271
Settlement of class B common shares in connection with recapitalization, shares exchanged (in shares)			3,527,246
Settlement of class B common shares in connection with Recapitalization, cash exchanged			$ 69,099
Retirement of class B common shares in connection with recapitalization, shares retired (in shares)			4,328,552
Dividends declared per common share (in dollars per share)			$ 0.60