Name:	cbre_LoanReceivableMortgageWarehouseLendingCurrent
Namespace Prefix:	cbre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Net increase (decrease) in mortgage servicing rights included in warehouse receivables.

No definition available.

Name:	cbre_NetIncreaseDecreaseInMortgageServicingRightsIncludedInWarehouseReceivables
Namespace Prefix:	cbre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Sale of mortgage loans held for sale.

No definition available.

Name:	cbre_SaleOfMortgageLoansHeldForSale
Namespace Prefix:	cbre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Warehouse receivables and warehouse lines of credit.

No definition available.

Name:	cbre_WarehouseReceivablesAndWarehouseLinesOfCreditAbstract
Namespace Prefix:	cbre_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Net gain (loss) resulting from the sales of securitized, pay-through debt securities collateralized by real estate mortgage loans (mortgages).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13)(h))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

Name:	us-gaap_GainLossOnSalesOfMortgageBackedSecuritiesMBS
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount of cash paid for the origination of mortgages that are held for sale.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-21

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 25
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-25

Name:	us-gaap_PaymentsForOriginationOfMortgageLoansHeldForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

Name:	us-gaap_ProceedsFromCollectionOfLoansHeldForSaleAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The cash inflow from collection of repayments from borrowers on loans that are secured with real estate mortgages and are held with the intention to resell in the near future.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-21

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 16
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-16

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

The cash inflow from sales of loans that are secured with real estate mortgages and are held with the intention to resell in the near future.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 25
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-25

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-21