Equity Items - Summary of Reconciliation of Changes in Stockholders' Equity (Parenthetical) (Details) - shares	3 Months Ended	6 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Equity [Abstract]
Common shares issued	208,564	93,738	279,025	234,352

Reconciliation of changes in stockholders equity stock issued during period shares new issues.

No definition available.

Name:	ash_ReconciliationOfChangesInStockholdersEquityStockIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	ash_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration