Subsequent Events - Narrative (Details) $ / shares in Units, ft² in Millions						3 Months Ended		12 Months Ended
	May 13, 2019 USD ($) shares	May 01, 2019 shares	Apr. 30, 2019 USD ($) ft² property state building $ / shares shares	Mar. 13, 2019 $ / shares	May 09, 2018 $ / shares	Mar. 31, 2019 USD ($) state Property building $ / shares	Mar. 31, 2018 USD ($) $ / shares	Dec. 31, 2018 USD ($)	May 06, 2019 USD ($) $ / shares	Apr. 29, 2019 shares
Subsequent Event [Line Item]
Issuance of shares for distribution reinvestment plan | $						$ 3,323,000	$ 5,483,000	$ 0
Distributions declared, daily accrual (usd per share)					$ 0.0015068493	$ 0.14	$ 0.14
Number of buildings (building) | building						35
Number of properties (property) | Property						27
Number of states (state) | state						17
Debt finance costs paid | $						$ 0	$ 5,275,000
Subsequent Event
Subsequent Event [Line Item]
Distributions declared, daily accrual (usd per share)			$ 0.00150684932
Stock distribution declared (in usd per share)			$ 0.000273973
Partnership units issued upon conversion (shares) | shares			1
Number of buildings (building) | building			124
Number of properties (property) | property			101
Number of states (state) | state			25
Rentable area (in sq ft) | ft²			27.2
Weighted average remaining lease term			7 years 5 months 23 days
Subsequent Event | Distribution Reinvestment Plan
Subsequent Event [Line Item]
Issuance of shares for distribution reinvestment plan (shares) | shares	7,396,052
Issuance of shares for distribution reinvestment plan | $	$ 70,300,000
Subsequent Event | Follow-on Offering
Subsequent Event [Line Item]
Issuance of shares for distribution reinvestment plan (shares) | shares	1,030,404
Issuance of shares for distribution reinvestment plan | $	$ 10,000,000
Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Common stock, par value (in USD per share)									$ 0.001
Self-tender offer amount | $									$ 100,000,000
Griffin Capital Essential Asset REIT, Inc. | Subsequent Event
Subsequent Event [Line Item]
Common stock, par value (in USD per share)			$ 0.001
Common Class E | Subsequent Event
Subsequent Event [Line Item]
Common stock, par value (in USD per share)			$ 0.001
New shares issued upon conversion (shares)			1.04807
New partnership units issued upon conversion (shares)			1.04807
Common Class E | Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Cash purchase price (in usd per share)									$ 9.56
Series A Preferred Stock | Subsequent Event
Subsequent Event [Line Item]
Shares issued upon conversion (shares) | shares			1
Preferred stock authorized (shares) | shares										10,000,000
Preferred stock issued (shares) | shares			5,000,000
Preferred stock annual distribution rate (percent)			6.55%
Class A
Subsequent Event [Line Item]
Distributions declared, daily accrual (usd per share)				$ 0.0015068493
Class A | Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Cash purchase price (in usd per share)									9.56
Class AA
Subsequent Event [Line Item]
Distributions declared, daily accrual (usd per share)				0.0015068493
Class AA | Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Cash purchase price (in usd per share)									9.56
Class AAA
Subsequent Event [Line Item]
Distributions declared, daily accrual (usd per share)				0.0015068493
Class AAA | Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Cash purchase price (in usd per share)									9.56
Class T
Subsequent Event [Line Item]
Distributions declared, daily accrual (usd per share)				0.00150684932
Class T | Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Cash purchase price (in usd per share)									9.66
Class D
Subsequent Event [Line Item]
Distributions declared, daily accrual (usd per share)				0.0015068493
Class D | Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Cash purchase price (in usd per share)									9.64
Class S | Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Cash purchase price (in usd per share)									9.65
Class I
Subsequent Event [Line Item]
Distributions declared, daily accrual (usd per share)				$ 0.0015068493
Class I | Subsequent Event | the Company Offer
Subsequent Event [Line Item]
Cash purchase price (in usd per share)									$ 9.64
Revolving Credit Facility | 2026 Term Commitment | Subsequent Event
Subsequent Event [Line Item]
Revolving credit facility current borrowing capacity | $			$ 150,000,000
Revolving Credit Facility | 2024 Term Commitment | Subsequent Event
Subsequent Event [Line Item]
Revolving credit facility current borrowing capacity | $			$ 400,000,000
Revolving Credit Facility | 2024 Term Loan | Subsequent Event
Subsequent Event [Line Item]
Initial term of debt instrument			5 years
Revolving Credit Facility | 2023 Term Loan | Subsequent Event
Subsequent Event [Line Item]
Initial term of debt instrument			5 years
Revolving Credit Facility | 2023 Term Commitment | Subsequent Event
Subsequent Event [Line Item]
Commitment fee (percent)			0.25%
Revolving credit facility current borrowing capacity | $			$ 200,000,000
Revolving Credit Facility | Revolving Commitment | Subsequent Event
Subsequent Event [Line Item]
Debt finance costs paid | $			$ 5,700,000
Revolving credit facility, extension term			1 year
Revolving credit facility, maximum borrowing capacity | $			$ 2,000,000,000.0
Minimum increment to commitment amount authorized | $			25,000,000
Authorized decrease in commitment amount | $			50,000,000
Minimum borrowing capacity | $			150,000,000
Revolving credit facility current borrowing capacity | $			$ 750,000,000
Initial term of debt instrument			3 years
Number of pool properties called by debt covenant | property			15
Maximum aggregate pool value to be contributed by single pool property or tenant (percent)			15.00%
Maximum aggregate pool value that may be contributed by Pool Properties subject to ground leases (percent)			15.00%
Maximum aggregate pool value that may be contributed by Pool Properties under development (percent)			20.00%
Minimum aggregate leasing percentage of all Pool Properties (percent)			90.00%
Asset pool leverage ratio (percent)			60.00%
Debt service coverage ratio			200.00%
Commitment fee | $			$ 25,000
Percentage of commitment (percent)			50.00%
Consolidated leverage ratio			60.00%
Consolidated tangible net worth (percent)			75.00%
Consolidated tangible net worth | $			$ 2,000,000,000
Consolidated net worth as a percentage of future equity issuances (percent)			75.00%
Consolidated fixed charge ratio			1.50
Maximum total secured debt ratio (percent)			40.00%
Increase to maximum total secured debt ratio upon closing of a material acquisition financed with secured debt (percent)			5.00%
Minimum unsecured interest coverage ratio			2.00
Maximum total secured recourse debt ratio			10.00%
Maximum unhedged variable rate debt as a percent of total asset value			30.00%
Maximum payout ratio			95.00%
Maximum unimproved land as a percentage of total asset value (percent)			5.00%
Maximum pre-leased assets under development as a percentage of total asset value (percent)			20.00%
Maximum investments in unconsolidated affiliates as a percentage of total asset value (percent)			10.00%
Maximum investments in mortgages receivable as a percentage of total asset value (percent)			15.00%
Maximum leased assets under renovation as a percentage of total asset value (percent)			10.00%
Maximum aggregate investments as a percentage of total asset value (percent)			25.00%
Revolving Credit Facility | Swingline advances | Subsequent Event
Subsequent Event [Line Item]
Revolving credit facility, maximum borrowing capacity | $			$ 125,000,000
Initial term of debt instrument			10 days
Revolving Credit Facility | 2026 Term Loan | Subsequent Event
Subsequent Event [Line Item]
Initial term of debt instrument			7 years
Minimum | Revolving Credit Facility | Revolving Commitment | Subsequent Event
Subsequent Event [Line Item]
Commitment fee (percent)			0.15%
Maximum | Revolving Credit Facility | Revolving Commitment | Subsequent Event
Subsequent Event [Line Item]
Commitment fee (percent)			0.20%
Consolidated leverage ratio			65.00%
Restricted Stock Units (RSUs) | Mr. Escalante | Executive Officers | Time-Based Restricted Stock Unit Agreements | Subsequent Event
Subsequent Event [Line Item]
RSUs issued (shares) | shares		732,218
Restricted Stock Units (RSUs) | Mr. Bitar | Executive Officers | Time-Based Restricted Stock Unit Agreements | Subsequent Event
Subsequent Event [Line Item]
RSUs issued (shares) | shares		104,603
Restricted Stock Units (RSUs) | Mr. Hirsch | Executive Officers | Time-Based Restricted Stock Unit Agreements | Subsequent Event
Subsequent Event [Line Item]
RSUs issued (shares) | shares		67,992
Restricted Stock Units (RSUs) | Mr. Sohn | Executive Officers | Time-Based Restricted Stock Unit Agreements | Subsequent Event
Subsequent Event [Line Item]
RSUs issued (shares) | shares		52,301
Restricted Stock Units (RSUs) | Mr. Tausk | Executive Officers | Time-Based Restricted Stock Unit Agreements | Subsequent Event
Subsequent Event [Line Item]
RSUs issued (shares) | shares		52,301