Interests in subsidiaries (Narrative) (Detail) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Notes Interests In Subsidiaries [Line Items]
Description of terms of contractual arrangements that could require parent or subsidiaries to provide financial support to consolidated structured entity	In 2019 and 2018, the Group did not enter into any contractual obligation that could require the Group to provide financial support to consolidated SEs.	In 2019 and 2018, the Group did not enter into any contractual obligation that could require the Group to provide financial support to consolidated SEs.
Support provided to consolidated structured entity without having contractual obligation to do so	$ 0	$ 0
Description of intentions to provide support to consolidated structured entity	In 2019 and 2018, the Group did not provide support, financial or otherwise, to an unconsolidated SE when not contractually obligated to do so, nor has the Group an intention to do so in the future.	In 2019 and 2018, the Group did not provide support, financial or otherwise, to an unconsolidated SE when not contractually obligated to do so, nor has the Group an intention to do so in the future.
UBS AG
Notes Interests In Subsidiaries [Line Items]
Support provided to consolidated structured entity without having contractual obligation to do so	$ 0	$ 0
Description of intentions to provide support to consolidated structured entity	The maximum exposure to loss disclosed in the table on the previous page does not reflect UBS AG’s risk management activities, including effects from financial instruments that may be used to economically hedge the risks inherent in the unconsolidated SE or the risk-reducing effects of collateral or other credit enhancements.	The maximum exposure to loss disclosed in the table on the previous page does not reflect UBS AG’s risk management activities, including effects from financial instruments that may be used to economically hedge the risks inherent in the unconsolidated SE or the risk-reducing effects of collateral or other credit enhancements.

The description of the entity's current intentions to provide financial or other support to a structured entity, including intentions to assist the structured entity in obtaining financial support.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2018-01-01
-Paragraph 17
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_17&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2018-01-01
-Paragraph 31
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_31&doctype=Standard
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The description of the terms of contractual arrangements that could require the parent or its subsidiaries to provide financial support to a structured entity, including events or circumstances that could expose the reporting entity to a loss (for example, liquidity arrangements or credit rating triggers associated with obligations to purchase assets of the structured entity or provide financial support). [Refer: Subsidiaries [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2018-01-01
-Paragraph 14
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_14&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/exampleRef
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The amount of financial or other support (for example, purchasing assets of, or instruments issued by, the structured entity) provided to a structured entity without having a contractual obligation to do so, including assistance in obtaining financial support. [Refer: Subsidiaries [member]; Unconsolidated structured entities [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-IssueDate 2018-01-01
-Paragraph 15
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-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_15_a&doctype=Standard
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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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.

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