Debt Instrument, Extended Term

No definition available.

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Namespace Prefix:	gcnl_
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- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ 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))
-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(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: 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(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
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

+ 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

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_DebtInstrumentLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: 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(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: 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(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

Debt - Schedule of Debt (Details) - USD ($)			9 Months Ended
Debt - Schedule of Debt (Details) - USD ($)	Apr. 01, 2017	Jul. 20, 2015	Sep. 30, 2016	Dec. 31, 2015	Jul. 09, 2015
Debt Instrument [Line Items]
Total principal			$ 1,462,975,000	$ 1,485,516,000
Unamortized Deferred Financing Costs and (Discounts) / Premiums			(10,555,000)	(12,089,000)
Total debt			1,452,420,000	1,473,427,000
Interest Rate Swap One
Debt Instrument [Line Items]
Derivative, notional amount			$ 825,000,000		$ 425,000,000
LIBOR
Debt Instrument [Line Items]
Effective interest rate (percent)			0.5311%
Revolving Credit Facility \| Term Loan (July 2015)
Debt Instrument [Line Items]
Total principal			$ 715,000,000	640,000,000
Effective interest rate (percent)			2.11%
Financing term (years)		4 years
Debt instrument, extended term (in years)		1 year
Revolving Credit Facility \| Term Loan (July 2015) \| LIBOR
Debt Instrument [Line Items]
Spread over variable rate (percent)			1.40%
Revolving Credit Facility \| Revolver Loan (July 2015)
Debt Instrument [Line Items]
Total principal			$ 382,409,000	481,653,000
Effective interest rate (percent)			2.30%
Revolving Credit Facility \| Revolver Loan (July 2015) \| LIBOR
Debt Instrument [Line Items]
Spread over variable rate (percent)			1.45%
Mortgages
Debt Instrument [Line Items]
Total principal			$ 365,566,000	363,863,000
Mortgages \| Plainfield mortgage loan
Debt Instrument [Line Items]
Total principal			$ 19,027,000	19,295,000
Contractual stated interest rate (percent)			6.65%
Effective interest rate (percent)			6.74%
Mortgages \| Emporia Partners mortgage loan
Debt Instrument [Line Items]
Total principal			$ 3,474,000	3,753,000
Contractual stated interest rate (percent)			5.88%
Effective interest rate (percent)			5.96%
Mortgages \| TransDigm mortgage loan
Debt Instrument [Line Items]
Total principal			$ 0	6,432,000
Contractual stated interest rate (percent)			5.98%
Effective interest rate (percent)			0.00%
Mortgages \| Ace Hardware mortgage loan
Debt Instrument [Line Items]
Total principal			$ 23,019,000	23,294,000
Contractual stated interest rate (percent)			5.588%
Effective interest rate (percent)			4.69%
Mortgages \| Highway 94 mortgage loan
Debt Instrument [Line Items]
Total principal			$ 18,376,000	18,968,000
Contractual stated interest rate (percent)			3.75%
Effective interest rate (percent)			5.07%
Mortgages \| DynCorp mortgage loan
Debt Instrument [Line Items]
Total principal			$ 0	11,162,000
Contractual stated interest rate (percent)			4.70%
Effective interest rate (percent)			0.00%
Mortgages \| Mercedes-Benz mortgage loan
Debt Instrument [Line Items]
Total principal			$ 18,618,000	18,945,000
Contractual stated interest rate (percent)			6.018%
Effective interest rate (percent)			6.10%
Mortgages \| Samsonite mortgage loan
Debt Instrument [Line Items]
Total principal			$ 23,984,000	24,561,000
Contractual stated interest rate (percent)			6.08%
Effective interest rate (percent)			4.96%
Mortgages \| HealthSpring mortgage loan
Debt Instrument [Line Items]
Total principal			$ 22,260,000	0
Contractual stated interest rate (percent)			4.18%
Effective interest rate (percent)			4.60%
Mortgages \| Midland Mortgage Loan
Debt Instrument [Line Items]
Total principal			$ 105,600,000	105,600,000
Contractual stated interest rate (percent)			3.94%
Effective interest rate (percent)			4.04%
Mortgages \| AIG Loan
Debt Instrument [Line Items]
Total principal			$ 110,640,000	110,640,000
Contractual stated interest rate (percent)			4.96%
Effective interest rate (percent)			5.14%
Mortgages \| TW Telecom Loan
Debt Instrument [Line Items]
Total principal			$ 20,568,000	$ 21,213,000
Effective interest rate (percent)			2.87%
Mortgages \| TW Telecom Loan \| LIBOR
Debt Instrument [Line Items]
Spread over variable rate (percent)			2.45%
Fixed and Variable Rate Debt
Debt Instrument [Line Items]
Weighted average interest rate			3.24%
Fixed Rate Debt
Debt Instrument [Line Items]
Weighted average interest rate			3.55%
Expected Reset \| Mortgages \| Ace Hardware mortgage loan
Debt Instrument [Line Items]
Contractual stated interest rate (percent)	8.90%
Expected Reset \| Mortgages \| Ace Hardware mortgage loan \| Ten Year Swap Rate
Debt Instrument [Line Items]
Spread over variable rate (percent)	5.00%