EQUITY METHOD INVESTMENT - Equity investee's summarized financial data (Details) - USD ($)	6 Months Ended	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
EQUITY METHOD INVESTMENT
Total external revenue		$ 1,672,378,581	$ 1,521,278,763
Gross profit		100,548,776	87,733,932
Net income before income taxes		16,688,287	7,502,011
Net income attributable to AMCON, net of tax		3,357,978	$ 183,579
Team Sledd | Equity method investment
EQUITY METHOD INVESTMENT
Total external revenue	$ 350,685,407	684,539,392
Gross profit	14,218,204	34,962,326
Net income before income taxes	551,280	8,597,997
Net income attributable to AMCON, net of tax	$ 183,579	$ 3,357,978