Related Party Transactions - Schedule of Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	$ 25,244	$ 45,084	$ 44,013
Payable as of December 31,	10,883	42,406
Operating expenses
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	0	3,594	2,652
Payable as of December 31,	0	74
Asset management fees
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	0	23,668	23,499
Payable as of December 31,	0	0
Property management fees
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	0	9,479	9,782
Payable as of December 31,	0	875
Disposition fees
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	641	177	1,950
Payable as of December 31,	0	0
Costs advanced by the advisor
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	3,771	546	587
Payable as of December 31,	1,164	341
Consulting fee - shared services
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	2,500	0	0
Payable as of December 31,	441	0
Acquisition fees
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	942	5,331	3,791
Payable as of December 31,	0	0
Leasing commissions
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	2,540	2,289	1,752
Payable as of December 31,	0	0
Earn-out
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	0	0	0
Payable as of December 31,	2,919	29,380
Other Fees
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	20	0	0
Payable as of December 31,	0	11,734
Revenue from Related Parties	0	0	0
Receivable as of December 31,	352	11,734
Stockholder Servicing Fee
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	692	0	0
Payable as of December 31,	4,994	0
Distributions
Related Party Transaction [Line Items]
Incurred for the Year Ended December 31,	14,138	0	0
Payable as of December 31,	1,365	2
Cash to be received from an affiliate related to deferred compensation and other payroll costs
Related Party Transaction [Line Items]
Revenue from Related Parties	658	0	0
Receivable as of December 31,	0	7,951
Griffin Capital Corporation | Payroll/Expense Allocation
Related Party Transaction [Line Items]
Revenue from Related Parties	481	0	0
Receivable as of December 31,	481	0
Griffin Capital Corporation | Reimbursable Expense Allocation
Related Party Transaction [Line Items]
Revenue from Related Parties	4	0	0
Receivable as of December 31,	4	0
Griffin Capital Essential Asset REIT II
Related Party Transaction [Line Items]
Revenue from Related Parties	8,892	0	0
Receivable as of December 31,	837	19,685
Griffin Capital Essential Asset REIT II | Payroll/Expense Allocation
Related Party Transaction [Line Items]
Revenue from Related Parties	1,217	0	0
Receivable as of December 31,	0	0
Griffin Capital Essential Asset REIT II | O&O Costs (including payroll allocated to O&O)
Related Party Transaction [Line Items]
Revenue from Related Parties	157	0	0
Receivable as of December 31,	0	0
Griffin Capital Essential Asset REIT II | Other Fees
Related Party Transaction [Line Items]
Revenue from Related Parties	6,375	0	$ 0
Receivable as of December 31,	$ 0	$ 0