Real Estate Investments (Purchase Price Allocation of Properties Acquired) (Details) $ in Thousands	Mar. 31, 2018 USD ($)
Assets
Land	$ 3,867
Building and improvements	15,470
Assets acquired	$ 19,337

Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Assets

No definition available.

Name:	roic_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
Namespace Prefix:	roic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant