Equity - Additional Information (Detail) - USD ($)									3 Months Ended	6 Months Ended
		Jun. 22, 2021	May 20, 2021	May 19, 2021	Mar. 17, 2021	Jan. 04, 2021	Dec. 20, 2019	Mar. 04, 2019	Jun. 30, 2021	Jun. 30, 2021
Stockholders Equity Note Disclosure [Line Items]
Unrecognized compensation expense									$ 8,900,000	$ 8,900,000
Contribution of property for common units, partial consideration			975,452
2015 Equity Incentive Plan [Member] | Employee [Member]
Stockholders Equity Note Disclosure [Line Items]
Grant of unvested restricted stock (in shares)					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
2021 ATM Programs [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
Number of Shares Sold									0	0
Gross sale of common stock available for grant									$ 300,000,000.0	$ 300,000,000.0
March 2019 ATM Program [Member]
Stockholders Equity Note Disclosure [Line Items]
Gross sale of common stock available for grant									0	0
December 2019 ATM Program [Member]
Stockholders Equity Note Disclosure [Line Items]
Gross sale of common stock available for grant									$ 111,800,000	$ 111,800,000
Restricted Common Stock [Member]
Stockholders Equity Note Disclosure [Line Items]
Aggregate Service-based units granted	[1]									284,528
Shares Issued, Shares, Share-based Payment Arrangement, Forfeited									32,385	32,385	[1]
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] | 2015 Equity Incentive Plan [Member] | Non-employee Director [Member]
Stockholders Equity Note Disclosure [Line Items]
Grant of unvested restricted stock (in shares)				6,647
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
Restricted Shares [Member]
Stockholders Equity Note Disclosure [Line Items]
Aggregate Service-based units granted										27,222
Grant of unvested restricted stock (in shares)				22,760
Shares Issued, Shares, Share-based Payment Arrangement, Forfeited									2,423	2,423
2015 Equity Incentive Plan [Member]
Stockholders Equity Note Disclosure [Line Items]
Compensation expense recognized										$ 2,400,000

[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.