Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 21,049,222	$ 33,978,453	$ 7,892,613
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	58,434,981	40,397,895	29,074,709
Amortization of deferred financing costs and mortgage premiums, net	(432,327)	(144,313)	494,843
Gain on consolidation of joint venture		(20,381,849)	(2,144,696)
Gain on bargain purchase			(3,864,145)
Straight-line rent adjustment	(3,794,936)	(3,733,913)	(3,040,510)
Amortization of above and below market rent	(6,944,572)	(4,444,117)	(3,659,011)
Amortization relating to stock based compensation	3,662,034	2,856,391	3,393,439
Provisions for tenant credit losses	2,315,972	1,621,940	1,160,568
Equity earned in earnings from unconsolidated joint ventures		(2,389,937)	(1,697,980)
Other noncash interest expense	1,847,640
Gain on sale of real estate	(4,868,553)
Loss on sale of discontinued operations		713,529
Settlement of interest rate swap agreements	(3,230,000)	(8,750,000)
Distribution of cumulative earnings from unconsolidated joint ventures			686,017
Other		792,244
Change in operating assets and liabilities
Restricted cash	190,011	74,083	(225,245)
Tenant and other receivables	(1,604,811)	(4,820,044)	(3,679,442)
Prepaid expenses	(1,106,227)	(104,814)	(573,099)
Accounts payable and accrued expenses	(1,164,032)	2,942,797	(1,912,490)
Other asset and liabilities, net	852,525	(855,880)	2,814,995
Net cash provided by operating activities	65,206,927	37,752,465	24,720,566
CASH FLOWS FROM INVESTING ACTIVITIES
Investments in real estate	(398,205,203)	(289,399,034)	(255,851,952)
Acquisition of entities		(43,378,106)
Proceeds from sale of real estate	27,622,089	5,607,612
Investments in mortgage notes receivables		(294,000)
Investments in unconsolidated joint ventures			(735,000)
Return of capital from unconsolidated joint ventures			8,661,211
Improvements to properties	(26,142,347)	(19,066,525)	(11,404,098)
Deposits on real estate acquisitions	(3,725,100)	1,225,000	(2,000,000)
Construction escrows and other	594,736	327,943	(244,639)
Net cash used in investing activities	(399,855,825)	(344,977,110)	(261,574,478)
CASH FLOWS FROM FINANCING ACTIVITIES
Principal repayment on mortgages	(21,981,922)	(14,902,386)	(7,874,618)
Proceeds from the draw on term loan/credit facility	549,300,000	342,950,000	209,000,000
Payments on credit facility	(449,750,000)	(405,000,000)
Payments on term loan	(200,000,000)
Payment of contingent consideration		(1,864,370)
Proceeds from exercise of warrants	70,723,391	226,529,778	12,000
Payments to acquire warrants		(32,785,921)
Proceeds from the sale of stock	214,906,251		37,811,658
Purchase of Non-controlling interest		(2,389)
Redemption of Operating Partnership Units	(3,280,000)	(2,189,779)
Distributions to Operating Partnership	(2,008,636)	(747,230)
Deferred financing and other costs	(3,188,618)	(4,097,377)	(2,792,050)
Registration expenditures	(9,512,944)	(69,245)	(1,162,787)
Dividends paid to common shareholders	(53,574,020)	(42,512,597)	(27,057,495)
Repurchase of common stock	(630,895)	(406,542)	(708,176)
Common shares issued under the 2009 Plan			22
Retirement of options		(274,830)
Net cash provided by financing activities	337,502,607	310,452,112	207,228,554
Net increase (decrease) in cash and cash equivalents	2,853,709	3,227,467	(29,625,358)
Cash and cash equivalents at beginning of period	7,919,697	4,692,230	34,317,588
Cash and cash equivalents at end of period	10,773,406	7,919,697	4,692,230
Supplemental disclosure of cash activities:
Cash paid on gross receipts and income for federal and state purposes	331,902	241,603	310,406
Interest paid	26,005,827	14,579,450	10,910,587
Other non-cash investing and financing activities – increase (decrease):
Issuance of OP Units in connection with acquisitions of entities	16,342,775	45,372,731
Assumed mortgage at fair value		62,749,675	19,668,352
Intangible lease liabilities	44,287,149	35,039,360	16,280,503
Transfer of equity investment in property to real estate investment		15,990,769	4,008,350
Interest rate swap asset	(1,948,243)	1,948,243
Accrued interest rate swap liabilities	(2,528,703)	6,733,812	4,156,096
Accrued real estate improvement costs	1,372,626	591,671	837,312
Senior Notes 2023 [Member] | Retail Opportunity Investments Partnership L.P. [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of Notes		245,825,000
Senior Notes 2023 [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of Notes		245,825,000
Senior Notes 2024 [Member] | Retail Opportunity Investments Partnership L.P. [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of Notes	246,500,000
Senior Notes 2024 [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of Notes	246,500,000
Retail Opportunity Investments Partnership L.P. [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	21,049,222	33,978,453	7,892,613
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	58,434,981	40,397,895	29,074,709
Amortization of deferred financing costs and mortgage premiums, net	(432,327)	(144,313)	494,843
Gain on consolidation of joint venture		(20,381,849)	(2,144,696)
Gain on bargain purchase			(3,864,145)
Straight-line rent adjustment	(3,794,936)	(3,733,913)	(3,040,510)
Amortization of above and below market rent	(6,944,572)	(4,444,117)	(3,659,011)
Amortization relating to stock based compensation	3,662,034	2,856,391	3,393,439
Provisions for tenant credit losses	2,315,972	1,621,940	1,160,568
Equity earned in earnings from unconsolidated joint ventures		(2,389,937)	(1,697,980)
Other noncash interest expense	1,847,640
Gain on sale of real estate	(4,868,553)
Loss on sale of discontinued operations		713,529
Settlement of interest rate swap agreements	(3,230,000)	(8,750,000)
Distribution of cumulative earnings from unconsolidated joint ventures			686,017
Other		792,244
Change in operating assets and liabilities
Restricted cash	190,011	74,083	(225,245)
Tenant and other receivables	(1,604,811)	(4,820,044)	(3,679,442)
Prepaid expenses	(1,106,227)	(104,814)	(573,099)
Accounts payable and accrued expenses	(1,164,032)	2,942,797	(1,912,490)
Other asset and liabilities, net	852,525	(855,880)	2,814,995
Net cash provided by operating activities	65,206,927	37,752,465	24,720,566
CASH FLOWS FROM INVESTING ACTIVITIES
Investments in real estate	(398,205,203)	(289,399,034)	(255,851,952)
Acquisition of entities		(43,378,106)
Proceeds from sale of real estate	27,622,089	5,607,612
Investments in mortgage notes receivables		(294,000)
Investments in unconsolidated joint ventures			(735,000)
Return of capital from unconsolidated joint ventures			8,661,211
Improvements to properties	(26,142,347)	(19,066,525)	(11,404,098)
Deposits on real estate acquisitions	(3,725,100)	1,225,000	(2,000,000)
Construction escrows and other	594,736	327,943	(244,639)
Net cash used in investing activities	(399,855,825)	(344,977,110)	(261,574,478)
CASH FLOWS FROM FINANCING ACTIVITIES
Principal repayment on mortgages	(21,981,922)	(14,902,386)	(7,874,618)
Proceeds from the draw on term loan/credit facility	549,300,000	342,950,000	209,000,000
Payments on credit facility	(449,750,000)	(405,000,000)
Payments on term loan	(200,000,000)
Payment of contingent consideration		(1,864,370)
Proceeds from exercise of warrants	70,723,391	226,529,778	12,000
Payments to acquire warrants		(32,785,921)
Proceeds from the sale of stock	214,906,251		37,811,658
Purchase of Non-controlling interest		(2,389)
Redemption of Operating Partnership Units	(3,280,000)	(2,189,779)
Distributions to Operating Partnership	(2,008,636)	(747,230)
Deferred financing and other costs	(3,188,618)	(4,097,377)	(2,792,050)
Registration expenditures	(9,512,944)	(69,245)	(1,162,787)
Dividends paid to common shareholders	(53,574,020)	(42,512,597)	(27,057,495)
Repurchase of common stock	(630,895)	(406,542)	(708,176)
Common shares issued under the 2009 Plan			22
Retirement of options		(274,830)
Net cash provided by financing activities	337,502,607	310,452,112	207,228,554
Net increase (decrease) in cash and cash equivalents	2,853,709	3,227,467	(29,625,358)
Cash and cash equivalents at beginning of period	7,919,697	4,692,230	34,317,588
Cash and cash equivalents at end of period	10,773,406	7,919,697	4,692,230
Supplemental disclosure of cash activities:
Cash paid on gross receipts and income for federal and state purposes	331,902	241,603	310,406
Interest paid	26,005,827	14,579,450	10,910,587
Other non-cash investing and financing activities – increase (decrease):
Issuance of OP Units in connection with acquisitions of entities	16,342,775	45,372,731
Assumed mortgage at fair value		62,749,675	19,668,352
Intangible lease liabilities	44,287,149	35,039,360	16,280,503
Transfer of equity investment in property to real estate investment		15,990,769	4,008,350
Interest rate swap asset	(1,948,243)	1,948,243
Accrued interest rate swap liabilities	(2,528,703)	6,733,812	4,156,096
Accrued real estate improvement costs	$ 1,372,626	$ 591,671	$ 837,312