Period of restriction of forfeiture.

No definition available.

Name:	pets_RestrictionPeriod
Namespace Prefix:	pets_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

+ References

+ Details

Name:	us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Aggregate number of common shares reserved for future issuance.

+ 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 210.5-02.29)
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Per share or unit weighted-average intrinsic value of award granted under share-based payment arrangement. Excludes share and unit options.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cash paid to settle liability for award under share-based payment arrangement.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI https://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=pets_The2016EmployeeEquityCompensationRestrictedStockPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=srt_ChiefExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=srt_ChiefFinancialOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=pets_PerformanceRestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=pets_OutsideDirectorEquityCompensationRestrictedStockPlan2015DirectorPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=pets_EmployeeAndDirectorPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=pets_A2022EmployeePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=pets_TwoThousandSixteenEmployeeEquityCompensationRestrictedStockPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Accounting for Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended		3 Months Ended		6 Months Ended
	Aug. 03, 2022	Jul. 31, 2022	Aug. 31, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
2016 Employee Plan \| Restricted Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Restricted common shares issued (in shares)				57,640		958,998
Restriction period			3 years
2016 Employee Plan \| Restricted Stock \| Chief Executive Officer
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issued restricted shares (in shares)			90,000
Issued restricted share price (in dollars per share)			$ 28.70
2016 Employee Plan \| Restricted Stock \| Chief Financial Officer
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issued restricted shares (in shares)	13,000
2016 Employee Plan \| Performance Restricted Stock \| Chief Executive Officer
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issued restricted shares (in shares)			510,000
Value of shares			$ 9.7
Issued restricted share price (in dollars per share)			$ 19.06
2016 Employee Plan \| Performance Restricted Stock \| Chief Financial Officer
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issued restricted shares (in shares)	3,000
2015 Director Plan \| Restricted Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Restricted common shares issued (in shares)				30,000		240,755
2015 Director Plan \| Restricted Stock \| Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Restriction period						1 year
2015 Director Plan \| Restricted Stock \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Restriction period						3 years
2016 Employee Plan and 2015 Director Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Compensation expense				$ 1.7	$ 0.9	$ 3.2	$ 1.6
2016 Employee Plan and 2015 Director Plan \| Restricted Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation cost				$ 12.2	$ 15.8	$ 12.2	$ 15.8
Nonvested restricted shares issued and outstanding (in shares)				776,928	734,669	776,928	734,669
2016 Employee Plan and 2015 Director Plan \| Restricted Stock \| Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Recognition period						1 year
2016 Employee Plan and 2015 Director Plan \| Restricted Stock \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Recognition period						3 years
2022 Employee Plan \| Restricted Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Restricted common shares issued (in shares)				0
Shares available for issuance (in shares)		1,000,000
2022 Employee Plan \| Restricted Stock \| Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Restriction period		1 year
2022 Employee Plan \| Restricted Stock \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Restriction period		10 years
2016 Employee Equity Compensation Restricted Stock Plan \| Chief Financial Officer
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Grant release restriction period	3 years