Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 0	$ 0
Class A Common Stock [Member]
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	16,657,135	16,182,151
Common stock, shares outstanding (in shares)	16,657,135	16,182,151
Class B Common Stock [Member]
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,409,738	2,409,738
Common stock, shares issued (in shares)	1,802,606	1,862,608
Common stock, shares outstanding (in shares)	1,802,606	1,862,608