Equity - Additional Information (Details) - USD ($)														1 Months Ended		3 Months Ended						9 Months Ended		12 Months Ended
	Nov. 03, 2020	Oct. 15, 2020	Oct. 08, 2020	Oct. 02, 2020	Aug. 20, 2020	Jul. 30, 2020	Jul. 01, 2020	Jun. 30, 2020	Apr. 30, 2020	Mar. 10, 2020	Feb. 20, 2020	Nov. 06, 2019	Aug. 06, 2019	Oct. 31, 2020	Jun. 30, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Aug. 17, 2020	Jul. 02, 2020
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)																100,000,000						100,000,000		100,000,000
Net proceeds from issuance of common and preferred stock																$ 1,622,000	$ 4,416,000	$ 1,349,000	$ 34,045,000	$ 7,498,000	$ 30,206,000
Preferred stock, par value (in dollars per share)																$ 0.01						$ 0.01		$ 0.01
Percentage of operating partnership held																73.80%						73.80%		72.60%
Acquisition of noncontrolling interest in real estate entity																	6,130,000
Aggregate Distribution (in thousands)																						$ 36,058,000	$ 43,537,000
Dividends per Share																$ 0.11		$ 0.22	$ 0.21	$ 0.21	$ 0.21
Class A units
Class of Stock [Line Items]
Class A Units not held by Company (in shares)																20,522,484						20,522,484
Additional paid-in capital
Class of Stock [Line Items]
Net proceeds from issuance of common and preferred stock																$ 1,620,000	4,411,000	$ 1,348,000	$ 34,025,000	$ 7,494,000	$ 30,185,000
Acquisition of noncontrolling interest in real estate entity																	2,386,000
Common stock
Class of Stock [Line Items]
Net proceeds from issuance of common and preferred stock																$ 2,000	5,000	1,000	$ 20,000	4,000	$ 21,000
Prior At-The-Market Program
Class of Stock [Line Items]
Consideration received on transaction																		$ 1,700,000
Prior At-The-Market Program | Common stock
Class of Stock [Line Items]
Maximum aggregate offering price of shares to be sold (up to)													$ 180,700,000
Shares issued (in shares)																		92,577
Weighted average price (in dollars per share)																		$ 18.23
The Amendments | Preferred stock
Class of Stock [Line Items]
Shares issued (in shares)																709,588
Consideration received on transaction																$ 16,000,000.0
Sale of stock, weighted average price per share																$ 22.87
The Amendments | Common stock
Class of Stock [Line Items]
Shares issued (in shares)																166,630						653,357
Consideration received on transaction																$ 1,700,000						$ 6,100,000
Sale of stock, weighted average price per share																$ 10.16						$ 9.50
Noncontrolling interests in investment entities
Class of Stock [Line Items]
Liquidation preference																$ 171,100,000						$ 171,100,000
Noncontrolling interests in investment entities | Operating Partnership
Class of Stock [Line Items]
Ownership interest percentage in properties																$ 500,000						$ 500,000
Consolidated Entities Under Development Or Construction | Operating Partnership
Class of Stock [Line Items]
Ownership interest percentage in properties																								$ 4,500,000
Redeemable convertible preferred stock
Class of Stock [Line Items]
Preferred stock, shares issued																6,843,418						6,843,418		2,530,000
Additonal shares authorized (in shares)																									3,600,000	3,450,000
Preferred stock, shares authorized (in shares)																9,980,000						9,980,000		2,930,000	9,980,000	6,380,000
Net proceeds from issuance of common and preferred stock																$ 101,369,000	91,000			61,001,000
Preferred Stock dividend rate percentage																						6.75%		6.75%
Redeemable convertible preferred stock | Additional paid-in capital
Class of Stock [Line Items]
Net proceeds from issuance of common and preferred stock																(6,370,000)	(5,000)			(2,249,000)
Redeemable convertible preferred stock | Preferred stock
Class of Stock [Line Items]
Net proceeds from issuance of common and preferred stock																$ 107,739,000	$ 96,000			$ 63,250,000
Redeemable convertible preferred stock | At The Market Program
Class of Stock [Line Items]
Maximum aggregate offering price of shares to be sold (up to)										$ 300,000,000.0
Preferred Stock dividend rate percentage										6.75%
Series A Preferred Stock
Class of Stock [Line Items]
Dividends per Share						$ 0.421875			$ 0.421875		$ 0.421875	$ 0.421875
Series A Preferred Stock | The Amendments
Class of Stock [Line Items]
Shares issued (in shares)																						713,418
Consideration received on transaction																						$ 16,100,000
Sale of stock, weighted average price per share																$ 22.88
Series A Preferred Stock | Public Stock Offering
Class of Stock [Line Items]
Weighted average price (in dollars per share)					$ 24.75
Consideration received on transaction					$ 86,100,000
Sale of stock, number of shares issued in transaction					3,600,000
Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued					3,600,000
Preferred Stock dividend rate percentage					6.75%
Common Class A
Class of Stock [Line Items]
Dividends per Share						$ 0.11					$ 0.22	$ 0.21
Common Class A | Common stock
Class of Stock [Line Items]
Shares issued (in shares)							756,697
1405 Point
Class of Stock [Line Items]
Percentage of voting interests acquired								21.00%							21.00%		21.00%
Note balance at assumption								$ 6,100,000
Remaining lease term								42 years							42 years		42 years
1405 Point | Additional paid-in capital
Class of Stock [Line Items]
Acquisition of noncontrolling interest in real estate entity															$ 2,400,000
Construction loans
Class of Stock [Line Items]
Borrowings under construction loans																						$ 38,200,000
Subsequent Event
Class of Stock [Line Items]
Percentage of voting interests acquired				20.00%
Note balance at assumption				$ 1,500,000
Subsequent Event | Class A units | Operating Partnership
Class of Stock [Line Items]
Aggregate Distribution (in thousands)			$ 2,300,000
Subsequent Event | Redeemable convertible preferred stock
Class of Stock [Line Items]
Aggregate Distribution (in thousands)		$ 2,900,000
Subsequent Event | Series A Preferred Stock | The Amendments
Class of Stock [Line Items]
Maximum aggregate offering price of shares to be sold (up to)	$ 277,500,000
Subsequent Event | Common Class A
Class of Stock [Line Items]
Aggregate Distribution (in thousands)			$ 6,400,000
Subsequent Event | Construction loans
Class of Stock [Line Items]
Borrowings under construction loans														$ 800,000