Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. This element represents information relating to other investments.

No definition available.

+ Details

Name:	cs_InvestmentOtherLineItems
Namespace Prefix:	cs_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The charge against earnings in the period to reduce the carrying amount of real property to fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2921-110230

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of investments classified as other.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(f,g))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated depreciation pertaining to real estate investments for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28.FN4)
-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04.(c) Schedule III)
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

+ Details

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

- Details

Name:	cs_FundsInOtherInvestmentsCategoriesAxis=us-gaap_EquityMethodInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cs_FundsInOtherInvestmentsCategoriesAxis=cs_NonmarketableEquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cs_FundsInOtherInvestmentsCategoriesAxis=cs_RealEstateHeldForInvestmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cs_RealEstateHeldForInvestmentTypeAxis=cs_ForeclosedOrRepossessedRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cs_RealEstateHeldForInvestmentTypeAxis=cs_ResidentialForeclosedOrRepossessedRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cs_FundsInOtherInvestmentsCategoriesAxis=us-gaap_LifeAndAnnuityInsuranceProductLineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=cs_ConsolidatedBankMember
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Period Type:

Other investments (Details) - CHF (SFr) SFr in Millions	12 Months Ended
Other investments (Details) - CHF (SFr) SFr in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other investments
Other investments	SFr 5,964	SFr 6,777
Equity method investments
Other investments
Other investments	3,066	3,121
Non-marketable equity securities
Other investments
Other investments	1,292	1,731
Real estate held for investment
Other investments
Other investments	232	268
Accumulated depreciation, real estate held for investment	389	386	SFr 365
Impairment charges	16	31	21
Real estate held for investment \| Foreclosed or Repossessed, Real Estate [Member]
Other investments
Other investments	41	29
Real estate held for investment \| Residential Foreclosed or Repossessed Real Estate [Member]
Other investments
Other investments	21	27
Life finance instruments
Other investments
Other investments	1,374	1,657
Bank
Other investments
Other investments	5,893	6,717
Bank \| Equity method investments
Other investments
Other investments	3,027	3,095
Bank \| Non-marketable equity securities
Other investments
Other investments	1,283	1,721
Bank \| Real estate held for investment
Other investments
Other investments	209	244
Accumulated depreciation, real estate held for investment	385	382	360
Impairment charges	16	31	SFr 21
Bank \| Real estate held for investment \| Foreclosed or Repossessed, Real Estate [Member]
Other investments
Other investments	41	29
Bank \| Real estate held for investment \| Residential Foreclosed or Repossessed Real Estate [Member]
Other investments
Other investments	21	27
Bank \| Life finance instruments
Other investments
Other investments	SFr 1,374	SFr 1,657