Quarterly Financial Data (Unaudited) - Schedule of Historical Consolidated Statements of Income (Parenthetical) (Detail) $ in Millions	3 Months Ended
Feb. 02, 2019 USD ($)
Quarterly Financial Data [Abstract]
Tax benefit related to TCJA	$ 24.0

Tax cuts and jobs act of 2017, incomplete accounting, provisional income tax expense (benefit).

No definition available.

Name:	jill_TaxCutsAndJobsActOf2017IncompleteAccountingProvisionalIncomeTaxExpenseBenefit
Namespace Prefix:	jill_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration