CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Allowance for doubtful accounts	$ 5,156	$ 4,797
Preferred stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	3,707,256	3,707,256
Preferred stock, shares outstanding (in shares)	3,567,543	3,677,318
Treasury stock, at cost (in shares)	144,594	99,446
Class A Common Stock
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	14,771,878	14,478,999
Common stock, shares outstanding (in shares)	14,627,284	14,379,553
Class B Common Stock
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	60,000,000	60,000,000
Common stock, shares issued (in shares)	20,800,000	20,800,000
Common stock, shares outstanding (in shares)	20,800,000	20,800,000