Credit Facility Number of Extension Options

No definition available.

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Period Type:	instant

- Definition

Debt Instrument, Extension, Term

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Represents line of credit fronting fee.

+ References

No definition available.

+ Details

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Namespace Prefix:	roic_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of additional borrowing capacity under the term loan.

+ References

No definition available.

+ Details

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

- 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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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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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-Section 50
-Paragraph 4
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

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

- Definition

The average effective interest rate during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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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Namespace Prefix:	us-gaap_
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

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.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

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

- Details

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- Details

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- Details

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Mortgage Notes Payable, Credit Facilities and Senior Notes (Details Textual)		3 Months Ended
	Sep. 08, 2017 USD ($) credit_facility_extension	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Nov. 10, 2017 USD ($)	Jun. 30, 2017 USD ($)	Jul. 26, 2016 USD ($)	Sep. 29, 2015 USD ($)	Dec. 03, 2014 USD ($)	Dec. 09, 2013 USD ($)
Term Loan Agreement
Debt Instrument [Line Items]
Debt instrument, face amount		$ 300,000,000	$ 300,000,000				$ 300,000,000.0
Additional borrowing capacity							$ 200,000,000
Long term debt		$ 300,000,000
Interest rate during period (percentage)		3.60%
Remaining borrowing capacity		$ 0
Senior Notes Due 2027 \| Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount		250,000,000	250,000,000	$ 250,000,000
Interest rate (percentage)				4.19%
Senior Notes Due 2026 \| Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount		200,000,000	200,000,000			$ 200,000,000.0
Interest rate (percentage)						3.95%
Senior Notes Due 2024 \| Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount		250,000,000	250,000,000					$ 250,000,000.0
Interest rate (percentage)								4.00%
Senior Notes Due 2023 \| Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount		$ 250,000,000	250,000,000						$ 250,000,000.0
Interest rate (percentage)									5.00%
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	$ 600,000,000				$ 500,000,000.0
Credit facility, number of extension options \| credit_facility_extension	2
Debt instrument, extension, term	6 months
Commitment fee (percentage)		0.20%
Fronting fee (percentage)		0.125%
Long-term, line of credit		$ 142,000,000	$ 156,000,000
Line of credit facility, interest rate during the period (percentage)		3.50%
Remaining borrowing capacity		$ 458,000,000
Revolving Credit Facility \| Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Variable rate (percentage)		0.50%
Revolving Credit Facility \| Eurodollar
Debt Instrument [Line Items]
Variable rate (percentage)		1.00%
Revolving Credit Facility \| Accordion Feature
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 1,200,000,000.0