Debt - Term Loan (Detail) - Amendment [Member]		3 Months Ended
May 08, 2015	Oct. 31, 2020
Debt Instrument [Line Items]
Debt instrument, interest rate description		The maturity date of the Amended Existing Term Loan Agreement continues to be May 8, 2022. Loans under the Amended Existing Term Loan Agreement continue to accrue interest at LIBOR plus 5.00%, with a minimum LIBOR per annum of 1.00%, with the interest payable on a quarterly basis. The Company may alternatively elect to accrue interest at a Base Rate (as defined in the Amended Existing Term Loan Agreement) plus 4.00%
Debt instrument, maturity date	May 08, 2022
Debt instrument, minimum LIBOR	1.00%
Debt instrument, periodic payment term	quarterly
Maximum percentage offer to repurchase existing term loans	100.00%
Existimg term loans offers accepted, percentage	97.90%
LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread rate	5.00%
Debt instrument, additional basis spread rate	4.00%

Debt instrument additional basis spread on variable rate.

No definition available.

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Namespace Prefix:	jill_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Existing term loan offers accepted, percentage.

+ References

No definition available.

+ Details

Name:	jill_ExistingTermLoanOffersAcceptedPercentage
Namespace Prefix:	jill_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

London interbank offered rate minimum percentage.

+ References

No definition available.

+ Details

Name:	jill_LondonInterbankOfferedRateMinimumPercentage
Namespace Prefix:	jill_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum percentage offered to repurchase existing term loans.

+ References

No definition available.

+ Details

Name:	jill_MaximumPercentageOfferedToRepurchaseExistingTermLoans
Namespace Prefix:	jill_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the frequency of periodic payments (monthly, quarterly, annual).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Period Type: