Common Stock of ROIC (Details Textual) - USD ($)	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020	Feb. 20, 2020	Dec. 31, 2019	Jul. 31, 2013
Class of Stock [Line Items]
Common stock, par value (in dollars per share)		$ 0.0001		$ 0.0001
Stock repurchase program, authorized amount					$ 50,000,000.0
Repurchase of common stock (in shares)		673,868
Repurchase of common stock	$ 8,846,000	$ 8,800,000
Sales Agreement
Class of Stock [Line Items]
Common stock, par value (in dollars per share)			$ 0.0001
Common shares that may be sold under a sales agreement, aggregate offering price, maximum			$ 500,000,000.0
Shares sold during the period (in shares)		0