Investments in Unconsolidated Entities - Summary of Properties Contributed In Unconsolidated Entities (Parenthetical) (Detail) - USD ($)			3 Months Ended		12 Months Ended
		Mar. 20, 2018	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Sep. 27, 2019
Related Party Transaction [Line Items]
Gain on sale of real estate			$ 24,208,000	$ 20,788,000
Mark 302 JV [Member]
Related Party Transaction [Line Items]
Contribution Date	[1]		Mar. 20, 2018
Cockeysville JV [Member]
Related Party Transaction [Line Items]
Contribution Date	[2]		Mar. 29, 2019
Tech Ridge JV [Member]
Related Party Transaction [Line Items]
Contribution Date	[3]		Sep. 27, 2019
Invesco Real Estate [Member] | Santa Monica, CA [Member] | Mark 302 JV [Member]
Related Party Transaction [Line Items]
Accounts Payable On Sale Of Investment Real Estate On Final Contribution Value					$ 15,000,000.0
Real estate fee paid on sale of real estate based on final contribution value					$ 1,100,000
Invesco Real Estate [Member] | Santa Monica, CA [Member] | Mark 302 JV [Member] | Maximum [Member]
Related Party Transaction [Line Items]
Contribution Date		Dec. 31, 2020			Sep. 30, 2021
Final contribution value		$ 105,000,000.0			$ 90,000,000.0
Gain or loss on sale of real estate based on final contribution value		53,800,000			30,000,000.0
Contribution value		105,000,000.0			90,000,000.0
Invesco Real Estate [Member] | Santa Monica, CA [Member] | Mark 302 JV [Member] | Minimum [Member]
Related Party Transaction [Line Items]
Final contribution value		60,000,000.0			60,000,000.0
Gain or loss on sale of real estate based on final contribution value		8,800,000
Reduction in Final contribution value					15,000,000.0
Contribution value		$ 60,000,000.0			$ 60,000,000.0
Invesco Real Estate [Member] | West Hartford, CT [Member] | Tech Ridge JV [Member] | Minimum [Member]
Related Party Transaction [Line Items]
Final contribution value						$ 2,750,000
Contribution value						$ 2,750,000

[1] The Mark 302 JV is subject to a revaluation upon the earlier of the first anniversary of project stabilization or December 31, 2020. The primary inputs in determining the Contribution Value for the Mark 302 JV are property operating income based on signed leases and total project costs and the Contribution Value will be recalculated to yield a pre-determined rate of return to the investment fund managed by Invesco Real Estate.  The Contribution Value cannot be more than $105.0 million or less than $60.0 million, and the Gain (Loss) will not be more than $53.8 million or less than $8.8 million. During the year ended December 31, 2020 the Company adjusted the Contribution Value down to $60.0 million and reduced the Gain (Loss) by $30.0 million which is included in gain on sale of real estate on the consolidated statements of operations. The Company also recorded a $15.0 million reduction to the Mark 302 JV investment value and a $15.0 million payable related to the amounts due to its partner which is included in accounts payable, accrued expenses and other liabilities on the consolidated balance sheets.  In addition, 2020, the Company and its partner entered into an agreement to extend the revaluation date for the Mark 302 JV to September 30, 2021. Pursuant to the terms of this agreement, the Company will pay its partner a fee of $1.1 million and the Contribution Value cannot be more than $90.0 million or less than $60.0 million. The Company will continue to re-evaluate the expected amount on a periodic basis through the final determination date

[2] The Cockeysville JV is subject to revaluation if an affiliate of Greenberg Gibbons contributes another adjacent parcel of land (the “Additional Land Parcel”) to the joint venture which was conditioned on certain milestones being met with respect to entitling the Additional Land Parcel for residential use. The Additional Land Parcel has been entitled for residential use. The Company has not reflected the contribution value of the Additional Land Parcel in the value of its investment in the Cockeysville JV based on uncertainty related to a potential alternative transaction with respect to the Additional Land Parcel. The Company will record an increased investment in the Cockeysville JV and additional gain in an amount equal to 50% of the fair value of the Additional Land Parcel at the earlier of when it becomes probable that the Additional Land Parcel will be contributed or upon an alternate outcome.

[3] The Tech Ridge JV is subject to a revaluation primarily based upon the number of residential units constructed by the Tech Ridge JV.  The Contribution Value cannot be less than $2.75 million.