FVM - Valuation adjustments: Own credit adjustments on financial liabilities designated at fair value (Detail) - Included in Other comprehensive income - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Recognized during the period
Realized gain / (loss)	$ 8	$ 1	$ 6	$ 9	$ 6
Unrealized gain / (loss)	(1,103)	1,156	66	53	(260)
Total gain / (loss), before tax	(1,095)	1,156	72	62	(254)
Recognized on the balance sheet as of the end of the period
Unrealized life-to-date gain / (loss)	$ (31)	$ 1,069	$ 60	$ (31)	$ 60

The amount of other comprehensive income, before tax, related to change in the fair value of financial liability attributable to change in the credit risk of the liability. [Refer: Other comprehensive income, before tax; Credit risk [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 7
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_7&doctype=Standard
-URIDate 2019-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 91
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_91_b&doctype=Standard
-URIDate 2019-03-27

+ Details

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

- Definition

A component of equity representing the accumulated change in fair value of financial liabilities attributable to change in the credit risk of the liabilities. [Refer: Credit risk [member]; Financial liabilities]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 78
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_78_e&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_ReserveOfChangeInFairValueOfFinancialLiabilityAttributableToChangeInCreditRiskOfLiability
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The realized amount of other comprehensive income, before tax, related to change in the fair value of financial liability attributable to change in the credit risk of the liability.

+ References

No definition available.

+ Details

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

- Definition

The unrealized amount of other comprehensive income, before tax, related to change in the fair value of financial liability attributable to change in the credit risk of the liability.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	ubs_AccountingTreatmentAxis=ubs_IncludedInOtherComprehensiveIncomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: