Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Retained earnings (Accumulated deficit)	Accumulated other comprehensive loss	Non- controlling interests	Officer [Member]	Officer [Member] Retained earnings (Accumulated deficit)	Two Thousand and Nine Stock Plan [Member] Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total (in shares)	99,531,034	99,531,034
Balance (in shares) at Dec. 31, 2015	99,531,034	99,531,034
Balance at Dec. 31, 2015	$ 1,131,342	$ 10	$ 1,166,395	$ (122,991)	$ (6,743)	$ 94,671
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under the 2009 Plan (in shares)									337,556
Repurchase of common stock (in shares)		(76,262)
Repurchase of common stock	(1,368)		(1,368)
Cancellation of restricted stock (in shares)		(7,332)
Stock based compensation expense	3,650		3,650
Issuance of OP Units to non-controlling interests	$ 48,175					48,175
OP Unit redemption (in shares)	613,762	613,762
OP Unit redemption	$ 12,982		12,982			(12,982)
Cash redemption for non-controlling interests	(7,182)					(7,182)
Adjustment to non-controlling interests ownership in Operating Partnership	0		(3,940)			3,940
Proceeds from the issuance of common stock (in shares)		8,757,254
Proceeds from the issuance of common stock	184,881	$ 1	184,880
Registration expenditures	(7,076)		(7,076)
Cash dividends	(62,125)			(55,863)		(6,262)	$ (133)	$ (133)
Net income attributable to Retail Opportunity Investments Corp.	23,133			23,133
Net income attributable to non-controlling interests	2,645					2,645
Other comprehensive income	$ 1,459				1,459
Total (in shares)	99,531,034	99,531,034
Proceeds on repayment of promissory note receivable secured by equity	$ 6,710					6,710
Balance (in shares) at Sep. 30, 2016	109,156,012	109,156,012
Balance at Sep. 30, 2016	$ 1,324,111	$ 11	1,355,523	(155,854)	(5,284)	129,715
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total (in shares)	109,156,012	109,156,012
Total	$ 1,317,401	$ 11	$ 1,355,523	$ (155,854)	$ (5,284)	$ 123,005