Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accounts and notes receivable, allowance	$ 11,235	$ 11,724
Property and equipment, accumulated depreciation	$ 15,835	$ 14,731
Common Class A
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	180,000,000	180,000,000
Common stock, shares issued	18,719,665	18,390,691
Common stock, shares outstanding	18,719,665	18,390,691
Common Class B
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,000	1,000
Common stock, shares issued	1	1
Common stock, shares outstanding	1	1