Selected Quarterly Financial Data (unaudited) - Summary of Certain Unaudited Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Aug. 31, 2020	May 31, 2020	Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018
Quarterly Financial Data [Abstract]
Sales	$ 5,528	$ 2,812	$ 19,388	$ 17,440	$ 18,753	$ 16,955	$ 15,117	$ 13,420	$ 45,168	$ 64,245	$ 51,744
Operating income (loss)	(6,839)	(8,028)	(240)	(1,391)	965	834	282	(420)	(16,498)	1,661	1,863
Net income (loss)	$ (6,849)	$ (9,152)	$ (133)	$ (1,224)	$ 916	$ 719	$ 212	$ (391)	$ (17,358)	$ 1,456	$ 1,742
Basic income (loss) per share of Class A and Class B common stock	$ (0.82)	$ (1.10)	$ (0.02)	$ (0.15)	$ 0.15	$ 0.14	$ 0.04	$ (0.08)	$ (2.08)	$ 0.28	$ 0.35
Diluted income (loss) per share of Class A and Class B common stock	$ (0.82)	$ (1.10)	$ (0.02)	$ (0.15)	$ 0.15	$ 0.14	$ 0.04	$ (0.08)	$ (2.08)	$ 0.26	$ 0.34