Represents line of credit fronting fee.

No definition available.

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Namespace Prefix:	roic_
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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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Namespace Prefix:	roic_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
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
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
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-Paragraph 8
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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
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

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
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

+ Details

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Namespace Prefix:	us-gaap_
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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-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

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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Namespace Prefix:	us-gaap_
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

- 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
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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

- Details

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Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=roic_SeniorNotes2024Member
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- Details

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- Details

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- Details

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- Details

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Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
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Balance Type:
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- Details

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- Details

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Mortgage Notes Payable, Credit Facilities and Senior Notes (Details Textual) - USD ($)		3 Months Ended
	Feb. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Nov. 10, 2017	Sep. 08, 2017	Jun. 30, 2017	Jul. 26, 2016	Sep. 29, 2015	Dec. 03, 2014	Dec. 09, 2013
Debt Instrument [Line Items]
Repayments of secured debt		$ 10,317,000	$ 189,000
Term Loan Agreement
Debt Instrument [Line Items]
Debt instrument, face amount		300,000,000		$ 300,000,000					$ 300,000,000
Additional borrowing capacity									$ 200,000,000
Long term debt		$ 300,000,000
Interest rate during period (percentage)		2.70%
Remaining borrowing capacity		$ 0
Senior Notes Due 2024
Debt Instrument [Line Items]
Debt instrument, face amount		250,000,000		250,000,000						$ 250,000,000.0
Interest rate (percentage)										4.00%
Interest expense, debt		2,500,000	2,500,000
Debt issuance costs, gross										$ 2,200,000
Amortization of debt discount (premium)		80,000	77,000
Senior Notes Due 2023
Debt Instrument [Line Items]
Debt instrument, face amount		250,000,000		250,000,000							$ 250,000,000.0
Interest rate (percentage)											5.00%
Interest expense, debt		3,100,000	3,100,000
Debt issuance costs, gross											$ 2,600,000
Amortization of debt discount (premium)		$ 95,000	94,000
Santa Teresa Village
Debt Instrument [Line Items]
Repayments of secured debt	$ 10,100,000
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
Commitment fee (percentage)		0.20%
Fronting fee (percentage)		0.125%
Long-term, line of credit		$ 159,500,000		143,500,000
Line of credit facility, interest rate during the period (percentage)		2.60%
Remaining borrowing capacity		$ 440,500,000
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%
Senior Notes \| Senior Notes Due 2027
Debt Instrument [Line Items]
Debt instrument, face amount		$ 250,000,000		250,000,000	$ 250,000,000
Interest rate (percentage)					4.19%
Interest expense, debt		2,600,000
Debt issuance costs, gross					$ 1,300,000
Senior Notes \| Senior Notes Due 2026
Debt Instrument [Line Items]
Debt instrument, face amount		200,000,000		$ 200,000,000				$ 200,000,000.0
Interest rate (percentage)								3.95%
Interest expense, debt		2,000,000	$ 2,000,000
Debt issuance costs, gross								$ 283,000
Accordion Feature \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 1,200,000,000.0