Consolidated statements of changes in equity (Parenthetical) SFr in Millions	12 Months Ended
Dec. 31, 2017 CHF (SFr)
Bank
Additional paid-in capital increase, capital contribution	SFr 4,100

The amount of the increase in additional paid-in capital due to capital contributions.

No definition available.

Name:	cs_AdditionalPaidinCapitalIncreaseCapitalContribution
Namespace Prefix:	cs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration