Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Allowance for doubtful accounts	$ 532	$ 489
Accumulated depreciation	32,480	30,387
Accumulated amortization	71,638	68,456
Current portion of long-term debt, net of financing fees	1,279	1,279
Non current portion of long-term debt, net of financing fees	$ 1,417	$ 1,486
Treasury stock, shares	204,393	160,733
Customer Relationships
Accumulated amortization	$ 59,862	$ 57,540
Other Intangible Assets
Accumulated amortization	$ 11,776	$ 10,916
Class A
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	25,731,640	25,609,758
Common stock, shares outstanding	25,527,247	25,449,025