Business Combination, Number of Loans Assumed

No definition available.

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- Definition

Additional borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents line of credit fee rate.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of liabilities incurred by the acquirer as part of consideration transferred in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The average effective interest rate during the reporting period.

+ References

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+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
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-Section S99
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Glossary Financing Activities
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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- Details

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- Details

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Period Type:

- Details

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- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=roic_MagnoliaShoppingCenterMember
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Balance Type:
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- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=roic_CasitasPlazaShoppingCenterMember
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Balance Type:
Period Type:

- Details

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- Details

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- Details

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Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=roic_LoanAgreementsMember
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Balance Type:
Period Type:

- Details

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Balance Type:
Period Type:

- Details

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- Details

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Mortgage Notes Payable, Credit Facilities and Senior Notes (Details Textual)			3 Months Ended		9 Months Ended
	Apr. 01, 2016 USD ($)	Mar. 10, 2016 USD ($) loan	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Jul. 26, 2016	Dec. 31, 2015 USD ($)	Sep. 29, 2015 USD ($)	Dec. 03, 2014 USD ($)	Dec. 09, 2013 USD ($)
Debt Instrument [Line Items]
Long term debt			$ 70,869,000		$ 70,869,000			$ 61,683,000
Number of loans assumed \| loan		2
Principal repayments on mortgages					7,630,000	$ 65,156,000
Term Loan Agreement
Debt Instrument [Line Items]
Long term debt			300,000,000		300,000,000			300,000,000	$ 300,000,000
Additional borrowing capacity									$ 200,000,000.0
Remaining borrowing capacity			$ 0		0
Interest rate during period (percentage)			1.60%
Senior Notes Due 2024
Debt Instrument [Line Items]
Long term debt			$ 250,000,000		250,000,000			250,000,000
Debt instrument, face amount										$ 250,000,000.0
Interest rate (percentage)										4.00%
Interest expense, debt			2,500,000	$ 2,500,000	7,500,000	7,500,000
Amortization of debt discount (premium)			75,000	72,000	224,000	215,000
Debt issuance costs, gross										$ 2,200,000
Senior Notes Due 2023
Debt Instrument [Line Items]
Long term debt			250,000,000		250,000,000			250,000,000
Debt instrument, face amount											$ 250,000,000.0
Interest rate (percentage)											5.00%
Interest expense, debt			3,100,000	3,100,000	9,400,000	9,400,000
Amortization of debt discount (premium)			91,000	$ 87,000	270,000	$ 256,000
Debt issuance costs, gross											$ 2,600,000
Gateway Shopping Center WA
Debt Instrument [Line Items]
Principal repayments on mortgages	$ 7,100,000
Magnolia Shopping Center
Debt Instrument [Line Items]
Long term debt			$ 9,179,000		$ 9,179,000			0
Loan incurred for acquisition		$ 9,300,000
Interest rate (percentage)			5.50%		5.50%
Casitas Plaza Shopping Center
Debt Instrument [Line Items]
Long term debt			$ 7,483,000		$ 7,483,000			0
Loan incurred for acquisition		$ 7,600,000
Interest rate (percentage)			5.32%		5.32%
Federal Funds Effective Swap Rate \| Term Loan Agreement
Debt Instrument [Line Items]
Variable rate (percentage)					0.50%
Eurodollar \| Term Loan Agreement
Debt Instrument [Line Items]
Variable rate (percentage)					1.10%
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 500,000,000.0		$ 500,000,000.0
Long-term, line of credit			8,000,000		8,000,000			135,500,000
Remaining borrowing capacity			$ 492,000,000		$ 492,000,000
Line of credit facility, interest rate during the period ( percentage)			1.50%
Revolving Credit Facility \| Federal Funds Effective Swap Rate \| Loan Agreements
Debt Instrument [Line Items]
Variable rate (percentage)					0.50%
Revolving Credit Facility \| Eurodollar \| Loan Agreements
Debt Instrument [Line Items]
Variable rate (percentage)					1.00%
Loan Agreements
Debt Instrument [Line Items]
Commitment fee (percentage)					0.20%
Fronting fee (percentage)			0.125%		0.125%
Accordion Feature \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 1,000,000,000.0		$ 1,000,000,000.0
Senior Notes \| Senior Notes Due 2026
Debt Instrument [Line Items]
Long term debt								$ 0
Debt instrument, face amount			200,000,000.0		200,000,000.0
Interest rate (percentage)							3.95%
Interest expense, debt			200,000		200,000
Debt issuance costs, gross			$ 300,000		$ 300,000