FVM - Transfers between Level 1 and Level 2 (Narrative) (Detail) SFr in Billions	6 Months Ended
Jun. 30, 2018 CHF (SFr)
Disclosure Of Fair Value Measurement [Line Items]
Transfers Out Of Level 2 Into Level 1 Of Fair Value Hierarchy Assets	SFr 0.6
Description Of Reasons For Transfers Out Of Level 2 Into Level 1 Of Fair Value Hierarchy Assets	due to increased levels of trading activity observed within the market.

The description of the reasons for transfers out of Level 2 and into Level 1 of the fair value hierarchy of assets held at the end of the reporting period. [Refer: Level 1 of fair value hierarchy [member]; Level 2 of fair value hierarchy [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 13
-IssueDate 2016-01-13
-Paragraph 93
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=13&date=2016-03-30&anchor=para_93_c&doctype=Standard
-URIDate 2016-03-31

+ Details

Name:	ifrs-full_DescriptionOfReasonsForTransfersOutOfLevel2IntoLevel1OfFairValueHierarchyAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of transfers out of Level 2 and into Level 1 of the fair value hierarchy of assets held at the end of the reporting period. [Refer: Level 1 of fair value hierarchy [member]; Level 2 of fair value hierarchy [member]]

+ References

+ Details

Name:	ifrs-full_TransfersOutOfLevel2IntoLevel1OfFairValueHierarchyAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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