Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Allowance	$ 153	$ 157
Class A common stock
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	140,000,000	140,000,000
Common stock, shares issued (in shares)	34,541,507	33,981,185
Common stock, shares outstanding (in shares)	34,541,507	33,981,185
Common Class B [Member]
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	35,000,000	35,000,000
Common stock, shares issued (in shares)	15,687,089	15,647,095
Common stock, shares outstanding (in shares)	15,687,089	15,647,095