Subsequent Events (Details) - UA Connected Fitness, Inc. - Subsequent Event - Disposal Group, Not Discontinued Operations $ in Millions	Oct. 28, 2020 USD ($)
Subsequent Event [Line Items]
Aggregate purchase price	$ 345
Purchase price due at closing	215
Maximum earnout payments	$ 130
Earnout payment period	3 years
Earnout payment, payable in 2022	$ 35
Earnout payment, payable in 2023	45
Earnout payment, payable in 2024	$ 50

Disposal Group, Including Discontinued Operation, Consideration, Due At Closing

No definition available.

Name:	ua_DisposalGroupIncludingDiscontinuedOperationConsiderationDueAtClosing
Namespace Prefix:	ua_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Disposal Group, Including Discontinued Operation, Consideration, Maximum Earnout Payments

+ References

No definition available.

+ Details

Name:	ua_DisposalGroupIncludingDiscontinuedOperationConsiderationMaximumEarnoutPayments
Namespace Prefix:	ua_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Disposal Group, Including Discontinued Operation, Earnout Payment Due In Year One

+ References

No definition available.

+ Details

Name:	ua_DisposalGroupIncludingDiscontinuedOperationEarnoutPaymentDueInYearOne
Namespace Prefix:	ua_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Disposal Group, Including Discontinued Operation, Earnout Payment Due In Year Three

+ References

No definition available.

+ Details

Name:	ua_DisposalGroupIncludingDiscontinuedOperationEarnoutPaymentDueInYearThree
Namespace Prefix:	ua_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Disposal Group, Including Discontinued Operation, Earnout Payment Due In Year Two

+ References

No definition available.

+ Details

Name:	ua_DisposalGroupIncludingDiscontinuedOperationEarnoutPaymentDueInYearTwo
Namespace Prefix:	ua_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Disposal Group, Including Discontinued Operation, Potential Earnout Payment Period

+ References

No definition available.

+ Details

Name:	ua_DisposalGroupIncludingDiscontinuedOperationPotentialEarnoutPaymentPeriod
Namespace Prefix:	ua_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=ua_UAConnectedFitnessIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: