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RELATED-PARTY TRANSACTIONS (Details) - USD ($)				3 Months Ended		9 Months Ended
RELATED-PARTY TRANSACTIONS (Details) - USD ($)	Dec. 18, 2017	Jun. 12, 2017	Sep. 14, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Oct. 01, 2015
Related-party transactions
Due to related parties				$ 10,838,000		$ 10,838,000		$ 8,814,000
Wholesaling agreement, percent of selling price fee per share						2.75%
Deferred costs				65,000		$ 65,000
Share repurchase							$ 576,000,000
CIM Urban REIT Management, L.P. \| Asset Management Fees
Related-party transactions
Fees				4,475,000	$ 4,971,000	13,350,000	17,515,000
Due to related parties				4,484,000		4,484,000		4,714,000
CIM Urban REIT Management, L.P. \| Property Management Fees
Related-party transactions
Fees				$ 1,084,000	1,229,000	$ 3,289,000	3,967,000
CIM Urban REIT Management, L.P. \| 0 - 500,000,000
Related-party transactions
Quarterly fee percentage				0.25%		0.25%
CIM Urban REIT Management, L.P. \| 0 - 500,000,000 \| Minimum
Related-party transactions
Daily average adjusted fair value of investments				$ 0		$ 0
CIM Urban REIT Management, L.P. \| 0 - 500,000,000 \| Maximum
Related-party transactions
Daily average adjusted fair value of investments				$ 500,000,000		$ 500,000,000
CIM Urban REIT Management, L.P. \| 500,000,000 - 1,000,000,000
Related-party transactions
Quarterly fee percentage				0.2375%		0.2375%
CIM Urban REIT Management, L.P. \| 500,000,000 - 1,000,000,000 \| Minimum
Related-party transactions
Daily average adjusted fair value of investments				$ 500,000,000		$ 500,000,000
CIM Urban REIT Management, L.P. \| 500,000,000 - 1,000,000,000 \| Maximum
Related-party transactions
Daily average adjusted fair value of investments				$ 1,000,000,000		$ 1,000,000,000
CIM Urban REIT Management, L.P. \| 1,000,000,000 - 1,500,000,000
Related-party transactions
Quarterly fee percentage				0.225%		0.225%
CIM Urban REIT Management, L.P. \| 1,000,000,000 - 1,500,000,000 \| Minimum
Related-party transactions
Daily average adjusted fair value of investments				$ 1,000,000,000		$ 1,000,000,000
CIM Urban REIT Management, L.P. \| 1,000,000,000 - 1,500,000,000 \| Maximum
Related-party transactions
Daily average adjusted fair value of investments				$ 1,500,000,000		$ 1,500,000,000
CIM Urban REIT Management, L.P. \| 1,500,000,000 - 4,000,000,000
Related-party transactions
Quarterly fee percentage				0.2125%		0.2125%
CIM Urban REIT Management, L.P. \| 1,500,000,000 - 4,000,000,000 \| Minimum
Related-party transactions
Daily average adjusted fair value of investments				$ 1,500,000,000		$ 1,500,000,000
CIM Urban REIT Management, L.P. \| 1,500,000,000 - 4,000,000,000 \| Maximum
Related-party transactions
Daily average adjusted fair value of investments				$ 4,000,000,000		$ 4,000,000,000
CIM Urban REIT Management, L.P. \| 4,000,000,000 - 20,000,000,000
Related-party transactions
Quarterly fee percentage				0.10%		0.10%
CIM Urban REIT Management, L.P. \| 4,000,000,000 - 20,000,000,000 \| Minimum
Related-party transactions
Daily average adjusted fair value of investments				$ 4,000,000,000		$ 4,000,000,000
CIM Urban REIT Management, L.P. \| 4,000,000,000 - 20,000,000,000 \| Maximum
Related-party transactions
Daily average adjusted fair value of investments				20,000,000,000		20,000,000,000
CIM Management Entities
Related-party transactions
Due to related parties				2,599,000		2,599,000		2,986,000
CIM Management Entities \| Personnel Fees
Related-party transactions
Fees				1,256,000	2,018,000	4,523,000	6,704,000
CIM Management Entities \| Lease Commission Fees
Related-party transactions
Fees				67,000	437,000	286,000	808,000
CIM Management Entities \| Construction Management Fees
Related-party transactions
Fees				65,000	233,000	506,000	508,000
CIM Management Entities And Related Parties
Related-party transactions
Due to related parties				1,098,000		1,098,000
Due from related parties								849,000
CIM Service Provider, LLC \| Base Service Fee
Related-party transactions
Fees				270,000	265,000	809,000	795,000
Fees payable per year under agreement				1,000,000		1,000,000
CIM Service Provider, LLC \| Master Services Agreement
Related-party transactions
Due to related parties				1,226,000		1,226,000		$ 1,963,000
Compensation expensed for performing other services				583,000	735,000	2,138,000	2,357,000
CIM SBA Staffing, LLC \| Personnel Fees
Related-party transactions
Due to related parties				1,388,000		1,388,000
Deferred personnel costs				97,000	154,000	233,000	308,000
CIM SBA Staffing, LLC \| Expenses Related to Lending Segment Subject to Reimbursement
Related-party transactions
Fees				740,000	845,000	1,980,000	2,473,000
CIM SBA Staffing, LLC \| Expenses Related to Corporate Services Subject to Reimbursement
Related-party transactions
Fees				53,000	80,000	198,000	319,000
CIM Management Entities Affiliate
Related-party transactions
Lease renewal term									5 years
Rental and other property income				27,000	$ 27,000	81,000	$ 81,000
December 2017 Share Repurchase \| Urban Partners II, LLC \| Common Stock
Related-party transactions
Stock repurchased and retired (in shares)	14,090,909	26,181,818	3,628,116
Share repurchase	$ 310,000,000	$ 576,000,000	$ 79,819,000
Aggregate purchase price (in usd per share)	$ 22	$ 22	$ 22
CCO Capital, LLC \| Wholesaling Agreement
Related-party transactions
Due to related parties				$ 43,000		$ 43,000