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Stock Redeemed or Called During Period, Weighted Average Price per Share

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Stock Repurchased During Period, Average Cost per Share

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Net asset value per share or per unit of investments in certain entities that calculate net asset value per share. Includes, but is not limited to, by unit, membership interest, or other ownership interest. Investment includes, but is not limited to, investment in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds. Excludes fair value disclosure.

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Cash received for fees during the current period. This element excludes cash proceeds from license fees.

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Amount of cash inflow from capital contributions to an entity associated with a dividend reinvestment plan.

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Cash received for the sale of real estate that is not part of an investing activity during the current period.

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Amount of real estate investments, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; (7) other real estate investments; (8) real estate joint ventures; and (9) unconsolidated real estate and other joint ventures not separately presented.

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Amount of transactions with related party during the financial reporting period.

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Number of shares issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the shareholders to reinvest dividends paid to them by the entity on new issues of stock by the entity.

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Value of stock issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the holder of the stock to reinvest dividends paid to them by the entity on new issues of stock by the entity.

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Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

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Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands									1 Months Ended	3 Months Ended		9 Months Ended			12 Months Ended			24 Months Ended
	Nov. 07, 2018	Nov. 02, 2018	Oct. 31, 2018	Oct. 03, 2018	Sep. 12, 2018	Mar. 08, 2018	Feb. 16, 2018	Jan. 31, 2018	Nov. 07, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Mar. 07, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Oct. 24, 2018
Subsequent Event [Line Items]
Common stock issued pursuant to the distribution reinvestment plan												$ 0
Stock redeemed during period (in shares)												2,791,262			790,941
Value of shares redeemed												$ 5,292
Dividends per share declared (in usd per share)					$ 0.0015068493					$ 0.14	$ 0.14	$ 0.42		$ 0.42
Subsequent Event
Subsequent Event [Line Items]
Dividends per share declared (in usd per share)						$ 0.00150684932
Subsequent Event \| Distribution Reinvestment Plan
Subsequent Event [Line Items]
Stock Issued During Period, Shares, Dividend Reinvestment Plan	7,372,224												4,818,911
Common stock issued pursuant to the distribution reinvestment plan	$ 70,200
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan													$ 45,600
Subsequent Event \| Follow-on Offering [Member]
Subsequent Event [Line Items]
Stock Issued During Period, Shares, Dividend Reinvestment Plan													299,515
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan													$ 2,800
Share Redemption Program
Subsequent Event [Line Items]
Stock redeemed during period (in shares)										585,525	146,083	1,306,834		413,842	623,499	167,442		790,941
Value of shares redeemed												$ 12,200			$ 5,700	$ 1,600		$ 7,400
Stock Redeemed or Called During Period, Weighted Average Price per Share										$ 9.65	$ 9.06	$ 9.36		$ 9.18	$ 9.21	$ 9.72		$ 9.32
Share Redemption Program \| Subsequent Event
Subsequent Event [Line Items]
Stock redeemed during period (in shares)								217,088
Value of shares redeemed				$ 6,700				$ 2,000
Stock Redeemed or Called During Period, Weighted Average Price per Share				$ 9.62				$ 9.09
Griffin Capital Essential Asset REIT, Inc. [Member]
Subsequent Event [Line Items]
Common stock issued pursuant to the distribution reinvestment plan												$ 33,667		$ 37,438	$ 49,541	$ 52,174	$ 52,557
Dividends per share declared (in usd per share)					$ 0.001901096					$ 0.17	$ 0.17	$ 0.51		$ 0.51
Griffin Capital Essential Asset REIT, Inc. [Member] \| Subsequent Event
Subsequent Event [Line Items]
Stock Issued During Period, Shares, Dividend Reinvestment Plan													19,135,619
Estimated net asset value per share (in usd per share)																			$ 10.05
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan													$ 196,500
Dividends per share declared (in usd per share)													$ 0.001901096
Griffin Capital Essential Asset REIT, Inc. [Member] \| Subsequent Event \| Distribution Reinvestment Plan
Subsequent Event [Line Items]
Number of shares issued (in shares)									22,100,900
Common stock issued pursuant to the distribution reinvestment plan									$ 226,300
Griffin Capital Essential Asset REIT, Inc. [Member] \| Share Redemption Program
Subsequent Event [Line Items]
Stock redeemed during period (in shares)										1,311,582	2,936,150	8,013,521		6,155,290	9,931,245	4,164,955
Value of shares redeemed												$ 76,900			$ 98,900	$ 41,400
Weighted average price per share (in dollars per share)										$ 9.63	$ 9.97	$ 9.60		$ 9.98	$ 9.96	$ 9.95
Griffin Capital Essential Asset REIT, Inc. [Member] \| Share Redemption Program \| Subsequent Event
Subsequent Event [Line Items]
Stock redeemed during period (in shares)			681,757
Value of shares redeemed			$ 6,700
Weighted average price per share (in dollars per share)			$ 9.76
Griffin Capital Essential Asset REIT, Inc. [Member] \| Quad Graphics Property \| Subsequent Event
Subsequent Event [Line Items]
Proceeds from sale of property		$ 10,700
Proceeds from termination fees, net closing costs and credits		3,900
Carrying value of property sold		$ 9,900
Advisor and Property Manager Fees - Performance Distribution [Member]
Subsequent Event [Line Items]
Performance Distribution, Percentage Of Total Return												12.50%			12.50%
Related Party Transaction, Amounts of Transaction							$ 1,200
Advisor and Property Manager Fees - Performance Distribution [Member] \| Subsequent Event
Subsequent Event [Line Items]
Related Party Transaction, Amounts of Transaction							1,200
Limited Partnership Units [Member] \| Advisor and Property Manager Fees - Performance Distribution [Member]
Subsequent Event [Line Items]
Related Party Transaction, Amounts of Transaction							1,200
Limited Partnership Units [Member] \| Advisor and Property Manager Fees - Performance Distribution [Member] \| Subsequent Event
Subsequent Event [Line Items]
Related Party Transaction, Amounts of Transaction							$ 1,200