Equity - Additional Information (Detail) - USD ($)						3 Months Ended
		Mar. 17, 2021	Jan. 04, 2021	Dec. 20, 2019	Mar. 04, 2019	Mar. 31, 2021
Stockholders Equity Note Disclosure [Line Items]
Unrecognized compensation expense						$ 10,100,000
2015 Equity Incentive Plan [Member]
Stockholders Equity Note Disclosure [Line Items]
Compensation expense recognized						$ 1,300,000
2015 Equity Incentive Plan [Member] | Employee [Member]
Stockholders Equity Note Disclosure [Line Items]
Grant of unvested restricted stock		4,462
Restricted common stock grants, vesting description						The shares of restricted common stock will vest upon the second anniversary of the grant date so long as the grantee remains an employee of the Company on such date
2017 and 2019 ATM Programs [Member]
Stockholders Equity Note Disclosure [Line Items]
Aggregate offering price of shares of common stock that the Company may issue and sell					$ 200,000,000.0
December 2019 ATM Program [Member]
Stockholders Equity Note Disclosure [Line Items]
Aggregate offering price of shares of common stock that the Company may issue and sell				$ 300,000,000.0
March 2019 ATM Program [Member]
Stockholders Equity Note Disclosure [Line Items]
Gross sale of common stock available for grant						$ 0
December 2019 ATM Program [Member]
Stockholders Equity Note Disclosure [Line Items]
Gross sale of common stock available for grant						$ 123,700,000
Restricted Common Stock [Member]
Stockholders Equity Note Disclosure [Line Items]
Aggregate Service-based units granted	[1]					277,881
Restricted Common Stock [Member] | 2015 Equity Incentive Plan [Member]
Stockholders Equity Note Disclosure [Line Items]
Aggregate performance-based units granted			164,178
Aggregate Service-based units granted			113,703
Restricted Common Stock [Member] | Tranche One [Member]
Stockholders Equity Note Disclosure [Line Items]
Aggregate performance-based units granted			82,070
Restricted Common Stock [Member] | Tranche Two [Member]
Stockholders Equity Note Disclosure [Line Items]
Aggregate performance-based units granted			82,108

[1] Reflects the number of LTIP units issued to the grantee on the grant date, which may be different from the number of LTIP units actually earned in the case of performance-based LTIP units.