Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated dividends in excess of earnings	Accumulated other comprehensive income (loss)	Non- controlling interests	Officer	Officer Accumulated dividends in excess of earnings	Officer Non- controlling interests
Balance (in shares) at Dec. 31, 2017		112,347,451
Balance at Dec. 31, 2017	$ 1,329,641	$ 11	$ 1,412,590	$ (210,490)	$ 1,856	$ 125,674
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the Equity Incentive Plan (in shares)		373,861
Shares issued under the Equity Incentive Plan	0		0
Shares withheld for employee taxes (in shares)		(70,168)
Shares withheld for employee taxes	(1,400)		(1,400)
Cancellation of restricted stock (in shares)		(4,999)
Stock based compensation expense	1,428		1,428
Adjustment to non-controlling interests ownership in Operating Partnership			(191)			191
Proceeds from the issuance of common stock (in shares)		75,314
Proceeds from the issuance of common stock	1,508	$ 0	1,508
Registration expenditures	(48)		(48)
Cash dividends	(24,258)			(21,981)		(2,277)	$ (72)	$ (72)
Net income attributable to Retail Opportunity Investments Corp.	10,702			10,702
Net income attributable to non-controlling interests	1,122					1,122
Other comprehensive income (loss)	3,808				3,808
Balance (in shares) at Mar. 31, 2018		112,721,459
Balance at Mar. 31, 2018	1,322,431	$ 11	1,413,887	(221,841)	5,664	124,710
Balance (in shares) at Dec. 31, 2017		112,347,451
Balance at Dec. 31, 2017	1,329,641	$ 11	1,412,590	(210,490)	1,856	125,674
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to Retail Opportunity Investments Corp.	32,235
Net income attributable to non-controlling interests	3,338
Balance (in shares) at Sep. 30, 2018		113,984,835
Balance at Sep. 30, 2018	1,325,583	$ 11	1,439,548	(244,690)	7,980	122,734
Balance (in shares) at Mar. 31, 2018		112,721,459
Balance at Mar. 31, 2018	1,322,431	$ 11	1,413,887	(221,841)	5,664	124,710
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of restricted stock (in shares)		(2,000)
Stock based compensation expense	1,991		1,991
Cash redemption for non-controlling interests	(560)					(560)
Adjustment to non-controlling interests ownership in Operating Partnership			(522)			522
Registration expenditures	(70)		(70)
Cash dividends	(24,256)			(21,980)		(2,276)	(88)	(88)
Net income attributable to Retail Opportunity Investments Corp.	7,339			7,339
Net income attributable to non-controlling interests	763					763
Other comprehensive income (loss)	1,571				1,571
Balance (in shares) at Jun. 30, 2018		112,719,459
Balance at Jun. 30, 2018	1,309,121	$ 11	1,415,286	(236,570)	7,235	123,159
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the Equity Incentive Plan (in shares)		14,000
Shares issued under the Equity Incentive Plan	145		145
Stock based compensation expense	1,996		1,996
Cash redemption for non-controlling interests	(1,432)					(1,432)
Adjustment to non-controlling interests ownership in Operating Partnership			(1,816)			1,816
Proceeds from the issuance of common stock (in shares)		1,251,376
Proceeds from the issuance of common stock	24,195	$ 0	24,195
Registration expenditures	(258)		(258)
Cash dividends	(24,489)			(22,227)		(2,262)	(87)	(87)
Net income attributable to Retail Opportunity Investments Corp.	14,194			14,194
Net income attributable to non-controlling interests	1,453					1,453
Other comprehensive income (loss)	745				745
Balance (in shares) at Sep. 30, 2018		113,984,835
Balance at Sep. 30, 2018	$ 1,325,583	$ 11	1,439,548	(244,690)	7,980	122,734
Balance (in shares) at Dec. 31, 2018	113,992,837	113,992,837
Balance at Dec. 31, 2018	$ 1,308,428	$ 11	1,441,080	(256,438)	3,561	120,214
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the Equity Incentive Plan (in shares)		445,022
Shares issued under the Equity Incentive Plan	0		0
Shares withheld for employee taxes (in shares)		(125,072)
Shares withheld for employee taxes	(1,986)		(1,986)
Cancellation of restricted stock (in shares)		(999)
Stock based compensation expense	1,651		1,651
Cash redemption for non-controlling interests	(1,246)					(1,246)
Adjustment to non-controlling interests ownership in Operating Partnership			56			(56)
Registration expenditures	(47)		(47)
Cash dividends	(24,766)			(22,519)		(2,247)	142	142
Net income attributable to Retail Opportunity Investments Corp.	13,250			13,250
Net income attributable to non-controlling interests	1,333					1,333
Other comprehensive income (loss)	(2,810)				(2,810)
Balance (in shares) at Mar. 31, 2019		114,311,788
Balance at Mar. 31, 2019	$ 1,293,949	$ 11	1,440,754	(265,565)	751	117,998
Balance (in shares) at Dec. 31, 2018	113,992,837	113,992,837
Balance at Dec. 31, 2018	$ 1,308,428	$ 11	1,441,080	(256,438)	3,561	120,214
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity redemption of OP units (in shares)	80,000	80,000
Equity redemption of OP Units	$ 1,472
Net income attributable to Retail Opportunity Investments Corp.	38,693
Net income attributable to non-controlling interests	$ 3,864
Balance (in shares) at Sep. 30, 2019	115,324,655	115,324,655
Balance at Sep. 30, 2019	$ 1,285,152	$ 12	1,461,432	(285,221)	(5,649)	114,578
Balance (in shares) at Mar. 31, 2019		114,311,788
Balance at Mar. 31, 2019	1,293,949	$ 11	1,440,754	(265,565)	751	117,998
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of restricted stock (in shares)		(3,999)
Stock based compensation expense	2,239		1,852			387
Adjustment to non-controlling interests ownership in Operating Partnership			592			(592)
Registration expenditures	(33)		(33)
Cash dividends	(24,764)			(22,517)		(2,247)	(65)	9	$ (74)
Net income attributable to Retail Opportunity Investments Corp.	7,585			7,585
Net income attributable to non-controlling interests	761					761
Other comprehensive income (loss)	(5,078)				(5,078)
Balance (in shares) at Jun. 30, 2019		114,307,789
Balance at Jun. 30, 2019	1,274,594	$ 11	1,443,165	(280,488)	(4,327)	116,233
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the Equity Incentive Plan (in shares)		50,000
Shares issued under the Equity Incentive Plan	512		512
Cancellation of restricted stock (in shares)		(1,999)
Stock based compensation expense	2,234		1,920			314
Equity redemption of OP units (in shares)		80,000
Equity redemption of OP Units			1,472			(1,472)
Cash redemption for non-controlling interests	(1,782)					(1,782)
Adjustment to non-controlling interests ownership in Operating Partnership			(1,780)			1,780
Proceeds from the issuance of common stock (in shares)		888,865
Proceeds from the issuance of common stock	16,351	$ 1	16,350
Registration expenditures	(207)		(207)
Cash dividends	(24,792)			(22,564)		(2,228)	$ (64)	$ (27)	$ (37)
Net income attributable to Retail Opportunity Investments Corp.	17,858			17,858
Net income attributable to non-controlling interests	1,770					1,770
Other comprehensive income (loss)	$ (1,322)				(1,322)
Balance (in shares) at Sep. 30, 2019	115,324,655	115,324,655
Balance at Sep. 30, 2019	$ 1,285,152	$ 12	$ 1,461,432	$ (285,221)	$ (5,649)	$ 114,578