Guarantees and commitments - Other guarantees (Details 2) - CHF (SFr) SFr in Billions	12 Months Ended
Jun. 30, 2020	Dec. 31, 2019
Guarantees
Amount jointly guaranteed by deposit-taking banks and securities dealers in Switzerland		SFr 6.0
Group's share in amount jointly guaranteed by deposit-taking banks and securities dealers in Switzerland	SFr 0.5

Represents the share of reporting entity in the total amount jointly guaranteed by deposit-taking banks and securities dealers in Switzerland in deposit insurance guarantee scheme.

No definition available.

Name:	cs_DepositInsuranceGuaranteeSchemeShareOfEntityInAmountGuaranteed
Namespace Prefix:	cs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration