Consolidated Statements of Shareholders' Equity (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Class A [Member]
Shares of treasury stock purchased (in shares)	87,203	218,344	132,836
Shares of common stock issued for the exercise of stock option (in shares)	227,902	468,318	197,784
Issuance of restricted common shares, net of forfeitures (in shares)	6,005	3,496	19,314
Dividends declared per common share (in dollars per share)	$ 0.78	$ 1.13	$ 0.40
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
Common Class B [Member]
Shares of treasury stock purchased (in shares)		3,677	15,074
Shares of common stock issued for the exercise of stock option (in shares)		9,296	13,600
Issuance of restricted common shares, net of forfeitures (in shares)			3,219
Dividends declared per common share (in dollars per share)		$ 0.60	$ 2.40
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