SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	6 Months Ended
Jun. 30, 2018
Accounting Policies [Abstract]
Minimum period of past due for loans to be placed on non accrual status	30 days

Represents the minimum period of past due for loans to be placed on non-accrual status.

No definition available.

Name:	acre_MinimumPeriodOfPastDueForLoansToBePlacedOnNonAccrual
Namespace Prefix:	acre_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration