Operating Leases - Schedule of Maturities of Lease Liabilities (Parenthetical) (Detail) $ in Thousands	12 Months Ended
Jan. 31, 2026 USD ($)
Leases [Abstract]
Minimum operating lease payments for leases signed but not taken possession	$ 0

Minimum operating lease payments for leases signed but not taken possession.

No definition available.

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