RELATED-PARTY TRANSACTIONS - Due to Related Parties (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Due to related parties	$ 9,423	$ 6,706
Asset management fees | Affiliated Entity
Related Party Transaction [Line Items]
Due to related parties	4,515	2,386
Property management fees and reimbursements | Affiliated Entity | CIM Management Entities
Related Party Transaction [Line Items]
Due to related parties	538	1,662
Expense reimbursements | Affiliated Entity | Non-segment
Related Party Transaction [Line Items]
Due to related parties	1,050	647
Expense reimbursements | Affiliated Entity | Operating Segments
Related Party Transaction [Line Items]
Due to related parties	1,880	690
Upfront dealer manager and trailing dealer manager fees | Affiliated Entity
Related Party Transaction [Line Items]
Due to related parties	679	493
Non-issuance specific offering costs | Affiliated Entity
Related Party Transaction [Line Items]
Due to related parties	698	668
Other amounts due to the CIM Management Entities and certain of its affiliates | Affiliated Entity | CIM Management Entities And Related Parties
Related Party Transaction [Line Items]
Due to related parties	$ 63	$ 160