Debt - Summary of Consolidated Indebtedness (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,826,271	$ 1,819,738
Net unamortized debt issuance costs		(7,045)	(7,946)
Unamortized premium		420	446
Mortgage and other notes payable, net		1,095,445	1,140,293
Unsecured notes payable, net		529,796	559,040
Total Indebtedness		1,819,646	1,812,238
Fund Portfolio | Fund II
Debt Instrument [Line Items]
Long-term debt, gross		256,212	255,978
Fund Portfolio | Fund III
Debt Instrument [Line Items]
Long-term debt, gross		35,970	34,728
Variable Rate
Debt Instrument [Line Items]
Long-term debt, gross	[1]	850,330	780,935
Mortgages
Debt Instrument [Line Items]
Net unamortized debt issuance costs		(3,315)	(3,958)
Unamortized premium		420	446
Mortgage and other notes payable, net		1,095,445	1,140,293
Mortgages | Core Portfolio
Debt Instrument [Line Items]
Long-term debt, gross		205,397	218,421
Mortgages | Fund Portfolio
Debt Instrument [Line Items]
Long-term debt, gross		386,653	388,410
Mortgages | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Long-term debt, gross		214,108	246,268
Unsecured Debt
Debt Instrument [Line Items]
Net unamortized debt issuance costs		(3,730)	(3,988)
Unsecured notes payable, net		529,796	559,040
Line of Credit
Debt Instrument [Line Items]
Unsecured notes payable, net		194,405	112,905
Fixed Rate
Debt Instrument [Line Items]
Long-term debt, gross	[2],[3]	975,941	1,038,803
Fixed Rate | Mortgages | Core Portfolio
Debt Instrument [Line Items]
Long-term debt, gross		$ 144,867	$ 145,464
Fixed Rate | Mortgages | Core Portfolio | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage		5.89%	5.89%
Maturity Date		2035-04
Fixed Rate | Mortgages | Core Portfolio | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage		3.88%	3.88%
Maturity Date		2024-02
Fixed Rate | Mortgages | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Interest rate, stated percentage		4.50%	4.50%
Maturity Date		2025-10
Long-term debt, gross		$ 1,120	$ 1,120
Fixed Rate | Mortgages | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Interest rate, stated percentage		3.35%	3.35%
Maturity Date		2023-05
Long-term debt, gross		$ 31,801	$ 31,801
Variable Rate Debt | Core Portfolio | LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		1.70%
Variable Rate Debt | Core Portfolio | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Variable Rate Debt | Fund Portfolio | Prime rate | Fund II
Debt Instrument [Line Items]
Basis spread on variable rate		2.00%
Variable Rate Debt | Fund Portfolio | LIBOR | Fund II
Debt Instrument [Line Items]
Basis spread on variable rate		2.75%
Variable Rate Debt | Fund Portfolio | LIBOR | Fund III
Debt Instrument [Line Items]
Basis spread on variable rate		3.10%
Variable Rate Debt | Fund Portfolio | LIBOR | Fund IV | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		3.65%
Variable Rate Debt | Fund Portfolio | LIBOR | Fund IV | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%
Variable Rate Debt | Fund Portfolio | LIBOR | Fund V | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		2.20%
Variable Rate Debt | Fund Portfolio | LIBOR | Fund V | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Variable Rate Debt | Mortgages | Fund Portfolio | Fund II
Debt Instrument [Line Items]
Maturity Date		2023-03
Variable Rate Debt | Mortgages | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Long-term debt, gross		$ 212,988	221,832
Variable Rate Debt | Mortgages | Fund Portfolio | Fund IV | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		3.65%
Variable Rate Debt | Mortgages | Fund Portfolio | Fund IV | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%
Variable Rate Debt | Mortgages | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Long-term debt, gross		$ 58,583	$ 58,878
Variable Rate Debt | Mortgages | Fund Portfolio | Prime rate | Fund II
Debt Instrument [Line Items]
Basis spread on variable rate		2.00%	2.00%
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund II
Debt Instrument [Line Items]
Basis spread on variable rate		2.75%	2.75%
Maturity Date		2022-08
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund III | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		3.10%	2.75%
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund III | Minimum
Debt Instrument [Line Items]
Maturity Date		2022-07
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund IV | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate			3.65%
Maturity Date		2026-06
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund IV | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			1.60%
Maturity Date		2022-06
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund V
Debt Instrument [Line Items]
Basis spread on variable rate		1.85%
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund V | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		2.76%
Maturity Date		2026-11
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund V | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			1.85%
Maturity Date		2022-06
Variable Rate Debt | Mortgages | Fund Portfolio | SOFR | Fund V
Debt Instrument [Line Items]
Basis spread on variable rate		2.76%
Variable Rate - Swapped | Mortgages | Core Portfolio
Debt Instrument [Line Items]
Long-term debt, gross	[4]	$ 60,530	$ 72,957
Variable Rate - Swapped | Mortgages | Core Portfolio | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	4.54%	4.54%
Maturity Date	[4]	2028-11
Variable Rate - Swapped | Mortgages | Core Portfolio | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	3.41%	3.41%
Maturity Date	[4]	2026-06
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Long-term debt, gross			$ 23,316
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund IV | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate			4.61%
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund IV | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			3.48%
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Long-term debt, gross	[4]	$ 296,269	$ 297,731
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund V | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	4.78%	4.78%
Maturity Date	[4]	2024-12
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund V | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	2.43%	2.95%
Maturity Date	[4]	2022-06
Variable Rate Unsecured Term Loans - Swapped | Unsecured Debt | Core Portfolio
Debt Instrument [Line Items]
Maturity Date	[4]	2026-06
Long-term debt, gross	[4]	$ 400,000	$ 400,000
Variable Rate Unsecured Term Loans - Swapped | Unsecured Debt | Core Portfolio | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	5.32%	5.32%
Variable Rate Unsecured Term Loans - Swapped | Unsecured Debt | Core Portfolio | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	3.65%	3.65%
Variable Rate Unsecured Term Loans - Swapped | Line of Credit | Core Portfolio
Debt Instrument [Line Items]
Maturity Date		2025-06
Long-term debt, gross		$ 153,051	$ 46,491
Variable Rate Unsecured Term Loans - Swapped | Line of Credit | Core Portfolio | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.40%	1.40%
Unsecured Notes Payable | Core Portfolio | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.55%
Unsecured Notes Payable | Unsecured Debt | Fund Portfolio | Fund II
Debt Instrument [Line Items]
Long-term debt, gross		$ 40,000	$ 40,000
Unsecured Notes Payable | Unsecured Debt | Fund Portfolio | LIBOR | Fund II
Debt Instrument [Line Items]
Basis spread on variable rate		2.25%	2.25%
Maturity Date		2022-09
Term Loan Subscription Facility | Unsecured Debt | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Long-term debt, gross		$ 0	$ 5,000
Term Loan Subscription Facility | Unsecured Debt | Fund Portfolio | SOFR | Fund IV
Debt Instrument [Line Items]
Basis spread on variable rate		2.01%	2.01%
Maturity Date		2022-12
Subscription Line | Unsecured Debt | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Long-term debt, gross		$ 93,526	$ 118,028
Subscription Line | Unsecured Debt | Fund Portfolio | LIBOR | Fund V
Debt Instrument [Line Items]
Basis spread on variable rate		1.90%	1.90%
Maturity Date		2022-05
Unsecured Line of Credit - Swapped | Line of Credit | Core Portfolio
Debt Instrument [Line Items]
Maturity Date	[4]	2025-06
Long-term debt, gross	[4]	$ 41,354	$ 66,414
Unsecured Line of Credit - Swapped | Line of Credit | Core Portfolio | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	5.32%	5.32%
Unsecured Line of Credit - Swapped | Line of Credit | Core Portfolio | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	3.65%	3.65%

[1] Includes $107.3 million and $110.5 million, respectively, of variable-rate debt that is subject to interest cap agreements.

[2] Fixed-rate debt at March 31, 2022 and December 31, 2021 includes $0.0 million and $0.0 million, respectively of Core swaps that may be used to hedge debt instruments of the Funds.

[3] Includes $798.2 million and $860.4 million, respectively, of variable-rate debt that has been fixed with interest rate swap agreements as of the periods presented.

[4] At March 31, 2022, the stated rates ranged from LIBOR + 1.50% to LIBOR +1.70% for Core variable-rate debt; LIBOR + 2.75% to PRIME + 2.00% for Fund II variable-rate debt; LIBOR + 3.10% for Fund III variable-rate debt; LIBOR 1.75% to LIBOR + 3.65% for Fund IV variable-rate debt; LIBOR + 1.50% to LIBOR + 2.20% for Fund V variable-rate debt; LIBOR + 1.55% for Core variable-rate unsecured term loans; and LIBOR + 1.40% for Core variable-rate unsecured lines of credit.