Common Stock of ROIC (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Feb. 20, 2020	Jul. 31, 2013
Class of Stock [Line Items]
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001	$ 0.0001
Proceeds from issuance of common stock		$ 69,602,000	$ 0	$ 34,162,000
Stock issuance costs		$ 740,000	$ 567,000	$ 478,000
Stock repurchase program, authorized amount						$ 50,000,000
Repurchase of common stock (in shares)		0
Sales Agreement
Class of Stock [Line Items]
Common stock, par value (in usd per share)					$ 0.0001
Common shares that may be sold under a sales agreement aggregate offering price, maximum					$ 500,000,000
Common stock issued (in shares)	1,261,650	3,788,035
Proceeds from issuance of common stock	$ 23,500,000	$ 69,600,000
Stock issuance costs	$ 235,000	$ 696,000