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, 2018		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 gain (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
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]
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
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 gain (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
Cash redemption for non-controlling interests	(1,782)					(1,782)
Equity Redemption of OP Units (in shares)		80,000
Redemption of OP Units			1,472			(1,472)
Adjustment to non-controlling interests ownership in Operating Partnership			(1,780)			1,780
Proceeds from the issuance of common stock, 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 gain (loss)	(1,322)				(1,322)
Balance (in shares) at Sep. 30, 2019		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 Dec. 31, 2019	116,496,016	116,496,016
Balance at Dec. 31, 2019	$ 1,291,828	$ 12	1,481,466	(297,998)	(4,132)	112,480
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the Equity Incentive Plan (in shares)		428,170
Shares issued under the Equity Incentive Plan	0		0
Shares withheld for employee taxes (in shares)		(128,614)
Shares withheld for employee taxes	(2,272)		(2,272)
Cancellation of restricted stock (in shares)		(1,000)
Stock based compensation expense	1,856		1,636			220
Cash redemption for non-controlling interests	(1,999)					(1,999)
Adjustment to non-controlling interests ownership in Operating Partnership			652			(652)
Repurchase of common stock (in shares)		(673,868)
Repurchase of common stock	(8,846)		(8,846)
Registration expenditures	(90)		(90)
Cash dividends	(25,460)			(23,273)		(2,187)	$ (89)	$ (56)	$ (33)
Net income attributable to Retail Opportunity Investments Corp.	12,002			12,002
Net income attributable to non-controlling interests	1,134					1,134
Other comprehensive gain (loss)	(8,717)				(8,717)
Balance (in shares) at Mar. 31, 2020		116,120,704
Balance at Mar. 31, 2020	$ 1,259,347	$ 12	1,472,546	(309,325)	(12,849)	108,963
Balance (in shares) at Dec. 31, 2019	116,496,016	116,496,016
Balance at Dec. 31, 2019	$ 1,291,828	$ 12	1,481,466	(297,998)	(4,132)	112,480
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity Redemption of OP Units (in shares)	1,823,350	1,823,350
Redemption of OP Units	$ 18,287
Repurchase of common stock (in shares)	(673,868)
Repurchase of common stock	$ (8,800)
Net income attributable to Retail Opportunity Investments Corp.	23,115
Net income attributable to non-controlling interests	$ 2,026
Balance (in shares) at Sep. 30, 2020	117,940,155	117,940,155
Balance at Sep. 30, 2020	$ 1,277,674	$ 12	1,493,989	(298,212)	(10,230)	92,115
Balance (in shares) at Mar. 31, 2020		116,120,704
Balance at Mar. 31, 2020	1,259,347	$ 12	1,472,546	(309,325)	(12,849)	108,963
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of restricted stock (in shares)		(2,499)
Stock based compensation expense	2,168		2,081			87
Equity Redemption of OP Units (in shares)		1,521,833
Redemption of OP Units			15,211			(15,211)
Adjustment to non-controlling interests ownership in Operating Partnership			(1,064)			1,064
Registration expenditures	6		6
Net income attributable to Retail Opportunity Investments Corp.	4,647			4,647
Net income attributable to non-controlling interests	389					389
Other comprehensive gain (loss)	264				1,201	(937)
Balance (in shares) at Jun. 30, 2020		117,640,038
Balance at Jun. 30, 2020	1,266,821	$ 12	1,488,780	(304,678)	(11,648)	94,355
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of restricted stock (in shares)		(1,400)
Stock based compensation expense	2,341		2,086			255
Equity Redemption of OP Units (in shares)		301,517
Redemption of OP Units			3,076			(3,076)
Adjustment to non-controlling interests ownership in Operating Partnership			64			(64)
Registration expenditures	(17)		(17)
Net income attributable to Retail Opportunity Investments Corp.	6,466			6,466
Net income attributable to non-controlling interests	503					503
Other comprehensive gain (loss)	$ 1,560				1,418	142
Balance (in shares) at Sep. 30, 2020	117,940,155	117,940,155
Balance at Sep. 30, 2020	$ 1,277,674	$ 12	$ 1,493,989	$ (298,212)	$ (10,230)	$ 92,115