Limited Partners' Capital Account, Number of Common Shares That Can Be Issued for Each Partnership Unit Redeemed

No definition available.

Name:	gcnl_LimitedPartnersCapitalAccountNumberofCommonSharesThatCanBeIssuedforEachPartnershipUnitRedeemed
Namespace Prefix:	gcnl_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of limited partner units issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

+ Details

Name:	us-gaap_LimitedPartnersCapitalAccountUnitsIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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

- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=gcnl_GriffinCapitalEssentialAssetOperatingPartnershipL.P.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=us-gaap_LimitedPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=gcnl_SharesOutstandingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=gcnl_WeightedAverageSharesOutstandingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=gcnl_GriffinCapitalEssentialAssetAdvisorIILLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Noncontrolling Interests - Narrative (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Feb. 16, 2018	Feb. 11, 2014
Operating Partnership
Noncontrolling Interest [Line Items]
Number of common shares that can be issued by Operating Partnership upon redemption of each limited partnership units (shares)	1
Operating Partnership \| Limited Partner
Noncontrolling Interest [Line Items]
Limited partnership units issued (in shares)			20,000
Price per partnership unit (in USD per share)			$ 10
Shares Outstanding \| Operating Partnership
Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners (percent)	0.19%
Weighted Average Shares Outstanding \| Operating Partnership
Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners (percent)	0.10%
The Advisor
Noncontrolling Interest [Line Items]
Limited partnership units issued (in shares)		123,779
Price per partnership unit (in USD per share)		$ 9.57