Equity - Vesting Schedule of the Nonvested Shares of Restricted Stock Outstanding (Detail) - shares		9 Months Ended
	Dec. 15, 2017	Sep. 30, 2020	Dec. 31, 2019
Restricted Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		236,739	212,545
Restricted Common Stock | October 1, 2020 - December 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		1,527
Restricted Common Stock | 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		96,773
Restricted Common Stock | 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		65,965
Restricted Common Stock | 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		47,214
Restricted Common Stock | 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		25,260
LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		292,751	298,412
LTIP Units | October 1, 2020 - December 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		154,422
LTIP Units | 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		90,031
LTIP Units | 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		45,740
LTIP Units | 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		2,558
LTIP Units | 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		0
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		687,761	687,761
Performance period		3 years
Performance Units | October 1, 2020 - December 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		188,250
Performance Units | 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		204,517
Performance Units | 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		294,994
Performance Units | 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		0
Performance Units | 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares (in shares)		0
Executive Officer | Amended 2013 Incentive Award Plan | Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period	3 years