Hedge accounting (Detail 6.2) - Hedges of net investments in foreign operations - Currency swap contract - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Gain Loss On Cash Flow Hedges Of Forecast Transactions Recognized In Earnings [Line Items]
Changes in fair value of hedging instruments	$ (142)	$ 205
Changes in fair value of hedged items	134	(205)
Effective portion of changes in fair value of hedging instruments recognised in Foreign currency translation OCI	(134)	181
Net gains / (losses) related to hedge ineffectiveness recognized in Other net income from financial instruments measured at fair value through profit or loss	(8)	24
UBS AG
Gain Loss On Cash Flow Hedges Of Forecast Transactions Recognized In Earnings [Line Items]
Changes in fair value of hedging instruments	(153)	199
Changes in fair value of hedged items	144	(199)
Effective portion of changes in fair value of hedging instruments recognised in Foreign currency translation OCI	(144)	181
Net gains / (losses) related to hedge ineffectiveness recognized in Other net income from financial instruments measured at fair value through profit or loss	$ (8)	$ 18

The gain (loss) on the change in fair value of the hedged item used as a basis for recognising hedge ineffectiveness. Hedge ineffectiveness is the extent to which the changes in the fair value or the cash flows of the hedging instrument are greater or less than those on the hedged item.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 24B
-Subparagraph a
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_24B_a_iv&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 24B
-Subparagraph b
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_24B_b_i&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_GainLossOnChangeInFairValueOfHedgedItemUsedAsBasisForRecognisingHedgeIneffectiveness
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The gain (loss) on the change in fair value of the hedging instrument used as a basis for recognising hedge ineffectiveness. Hedge ineffectiveness is the extent to which the changes in the fair value or the cash flows of the hedging instrument are greater or less than those on the hedged item.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 24A
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_24A_c&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_GainLossOnChangeInFairValueOfHedgingInstrumentUsedAsBasisForRecognisingHedgeIneffectiveness
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The gain (loss) recognised in profit or loss on hedge ineffectiveness. [Refer: Gain (loss) on hedge ineffectiveness]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 24C
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_24C_a_i&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 24C
-Subparagraph b
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_24C_b_ii&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_GainLossOnHedgeIneffectivenessRecognisedInProfitOrLoss
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	ubs_GainLossOnCashFlowHedgesOfForecastTransactionsRecognizedInEarningsLineItems
Namespace Prefix:	ubs_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the effective portion of changes in fair value of hedging instruments recognised in Foreign currency translation OCI

+ References

No definition available.

+ Details

Name:	ubs_GainLossOnHedgeIneffectivenessRecognisedInForeignCurrencyTranslationOtherComprehensiveIncome
Namespace Prefix:	ubs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	ifrs-full_TypesOfHedgesAxis=ifrs-full_HedgesOfNetInvestmentInForeignOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_HedgingInstrumentsAxis=ifrs-full_CurrencySwapContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ubs_UBSAGMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: