Condensed Consolidated Unaudited Statements of Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended	6 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Condensed Consolidated Unaudited Statements of Shareholders' Equity
Dividends on common stock	$ 0.18	$ 0.18	$ 0.64	$ 0.64

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