Condensed Consolidated Statements of Shareholders' Equity (Unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Treasury Stock [Member]
Shares of stock (in shares)	2,977	28,657
Common Stock [Member]
Shares of common stock for the exercise of stock options (in shares)	18,000	86,247
Shares of restricted common shares, net of (forfeitures) (in shares)		6,005
Dividends declared per common share (in dollars per share)	$ 0.19	$ 0.19
Common Class A [Member]
Shares of stock (in shares)			126,617	30,180
Shares of common stock for the exercise of stock options (in shares)			270,189	74,769
Shares of restricted common shares, net of (forfeitures) (in shares)				6,793
Dividends declared per common share (in dollars per share)			$ 0.17	$ 0.10
Forfeitures of class A restricted common shares (in shares)			10,289
Settlement of class B restricted common shares and stock options in connection with Recapitalization, number of shares (in shares)			90,369
Settlement of common shares in connection with Recapitalization, number of shares received (in shares)			3,527,246
Common Class B [Member]
Shares of stock (in shares)				3,677
Shares of common stock for the exercise of stock options (in shares)				9,296
Dividends declared per common share (in dollars per share)				$ 0.60
Settlement of class B restricted common shares and stock options in connection with Recapitalization, cash exchanged			$ 3,271
Settlement of common shares in connection with Recapitalization, number of shares settled (in shares)			3,527,246
Settlement of common shares in connection with Recapitalization, value of cash			$ 69,099
Retirement in connection with recapitalization, shares (in shares)			4,328,552