CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY (Parenthetical) - $ / shares	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018
CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY
Dividends on common stock	$ 1.00	$ 1.00

Aggregate special dividends declared per share of common stock.

No definition available.

Name:	dit_SpecialDividendsDeclaredOnCommonStock
Namespace Prefix:	dit_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration