FI - Roll-forward of liabilities measured at fair value on recurring basis (Details 6) - Recurring basis - Due to banks and customer deposits - CHF (SFr) SFr in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Liabilities measured at fair value on a recurring basis for level 3
Fair value, liabilities	SFr 433	SFr 474	SFr 495	SFr 453
Bank
Liabilities measured at fair value on a recurring basis for level 3
Fair value, liabilities	SFr 433	SFr 474	SFr 495	SFr 453

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant