Represents the credit facility term.

No definition available.

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Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be increased to, at the Company's option.

+ References

No definition available.

+ Details

Name:	cigi_LineOfCreditFacilityAdditionalBorrowingCapacity
Namespace Prefix:	cigi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	cigi_Note12LongtermDebtDetailsLineItems
Namespace Prefix:	cigi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

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-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ 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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

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-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

+ Details

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

- Details

Name:	us-gaap_StatementOperatingActivitiesSegmentAxis=us-gaap_SegmentContinuingOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cigi_FivePoint44PercentSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=cigi_OldFSVMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=cigi_SixPoint40PercentSeniorNotesMember
Namespace Prefix:
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Balance Type:
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- Details

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Note 12 - Long-term Debt (Details) - USD ($) $ in Thousands		1 Months Ended		12 Months Ended
Note 12 - Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 01, 2015	May. 31, 2015	Apr. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Note 12 - Long-term Debt (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity (in Dollars)	$ 525,000
Credit Facility Term	5 years
Debt Instrument, Interest Rate, Effective Percentage				3.60%	4.50%
Debt, Weighted Average Interest Rate				2.30%	2.00%
Line of Credit Facility, Remaining Borrowing Capacity (in Dollars)				$ 248,485
Letters of Credit Outstanding, Amount (in Dollars)				17,232	$ 7,770
Line of Credit Facility, Additional Borrowing Capacity (in Dollars)				$ 150,000
Continuing Operations [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Debt and Capital Lease Obligations (in Dollars)					253,991
FirstService [Member] \| Discontinued Operations [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Debt and Capital Lease Obligations (in Dollars)					$ 239,357
5.44% Senior Notes [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					5.44%
5.44% Senior Notes [Member] \| Old FSV [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Repayments of Secured Debt (in Dollars)			$ 20,000
Debt Instrument, Interest Rate, Stated Percentage			5.44%
6.40% Senior Notes [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.40%
6.40% Senior Notes [Member] \| Old FSV [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Repayments of Secured Debt (in Dollars)		$ 12,500
Debt Instrument, Interest Rate, Stated Percentage		6.40%
3.84% Notes [Member] \| FirstService [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.84%
Debt Instrument, Face Amount (in Dollars)	$ 150,000
Minimum [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	1.50%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.30%
Maximum [Member]
Note 12 - Long-term Debt (Details) [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.75%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.55%