Debt - Summary of Consolidated Indebtedness (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,819,738	$ 1,713,274
Net unamortized debt issuance costs		(7,946)	(5,978)
Unamortized Premium		446	548
Secured Debt, Total		1,140,293	1,148,586
Unsecured notes payable, net		559,040	420,858
Total Indebtedness		$ 1,812,238	1,707,844
SOFR | Fund IV
Debt Instrument [Line Items]
Basis spread on variable rate		2.01%
Fund Portfolio | Fund II
Debt Instrument [Line Items]
Long-term debt, gross		$ 255,978	228,282
Fund Portfolio | LIBOR | Fund V | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		2.20%
Fund Portfolio | LIBOR | Fund V | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Variable Rate
Debt Instrument [Line Items]
Long-term debt, gross	[1]	$ 780,935	589,019
Mortgages
Debt Instrument [Line Items]
Net unamortized debt issuance costs		(3,958)	(5,722)
Unamortized Premium		446	548
Secured Debt, Total		1,140,293	1,148,586
Mortgages | Core Portfolio
Debt Instrument [Line Items]
Long-term debt, gross		218,421	228,310
Mortgages | Fund Portfolio | Fund II
Debt Instrument [Line Items]
Long-term debt, gross		255,978	247,085
Mortgages | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Long-term debt, gross		246,268	306,740
Mortgages | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Long-term debt, gross		388,410	335,677
Unsecured Debt
Debt Instrument [Line Items]
Net unamortized debt issuance costs		(3,988)	(256)
Unsecured notes payable, net		559,040	420,858
Unsecured Debt | Core Portfolio
Debt Instrument [Line Items]
Long-term debt, gross		400,000	380,000
Line of Credit
Debt Instrument [Line Items]
Unsecured notes payable, net		112,905	138,400
Fixed Rate
Debt Instrument [Line Items]
Long-term debt, gross	[2],[3]	1,038,803	1,124,255
Fixed Rate | Mortgages | Core Portfolio
Debt Instrument [Line Items]
Long-term debt, gross		$ 145,464	$ 147,810
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%
Maturity Date		2025-10
Long-term debt, gross		$ 1,120	$ 6,726
Fixed Rate | Mortgages | Fund Portfolio | Fund IV | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage			4.50%
Fixed Rate | Mortgages | Fund Portfolio | Fund IV | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage			3.40%
Fixed Rate | Mortgages | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Interest rate, stated percentage		3.35%
Maturity Date		2023-05
Long-term debt, gross		$ 31,801
Variable Rate Debt | Core Portfolio | LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		1.90%
Variable Rate Debt | Core Portfolio | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Variable Rate Debt | Fund Portfolio | LIBOR | Fund III | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		2.75%
Variable Rate Debt | Mortgages | Fund Portfolio | Fund II
Debt Instrument [Line Items]
Maturity Date		2022-08
Variable Rate Debt | Mortgages | Fund Portfolio | Fund III
Debt Instrument [Line Items]
Long-term debt, gross		$ 34,728	35,948
Variable Rate Debt | Mortgages | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Long-term debt, gross		$ 221,832	$ 252,324
Variable Rate Debt | Mortgages | Fund Portfolio | Fund IV | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		3.65%	3.40%
Maturity Date		2026-06
Variable Rate Debt | Mortgages | Fund Portfolio | Fund IV | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.60%	1.60%
Maturity Date		2022-02
Variable Rate Debt | Mortgages | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Long-term debt, gross		$ 58,878	$ 1,354
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%	3.00%
Maturity Date		2022-03
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund III | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		2.75%	2.75%
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund III | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		2.75%	2.75%
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			2.20%
Maturity Date		2026-11
Variable Rate Debt | Mortgages | Fund Portfolio | LIBOR | Fund V | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			1.50%
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]	$ 72,957	$ 80,500
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]	2023-01
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund II
Debt Instrument [Line Items]
Interest rate, stated percentage			2.88%
Long-term debt, gross		$ 0	$ 18,803
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Long-term debt, gross	[4]	$ 23,316	$ 47,690
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund IV | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	[4]	4.61%	4.61%
Maturity Date	[4]	2022-12
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund IV | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	[4]	3.48%	3.48%
Maturity Date	[4]	2022-04
Variable Rate - Swapped | Mortgages | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Long-term debt, gross	[4]	$ 297,731	$ 334,323
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]	2022-02
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	$ 350,000
Variable Rate Unsecured Term Loans - Swapped | Unsecured Debt | Core Portfolio | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	5.32%	5.02%
Variable Rate Unsecured Term Loans - Swapped | Unsecured Debt | Core Portfolio | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	3.65%	2.49%
Variable Rate Unsecured Term Loans - Swapped | Line of Credit | Core Portfolio
Debt Instrument [Line Items]
Maturity Date		2025-06
Long-term debt, gross		$ 46,491	$ 0
Variable Rate Unsecured Term Loans - Swapped | Line of Credit | Core Portfolio | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		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%	1.65%
Maturity Date		2022-09
Term Loan Subscription Facility | Unsecured Debt | Fund Portfolio | Fund IV
Debt Instrument [Line Items]
Long-term debt, gross			$ 864
Term Loan Subscription Facility | Unsecured Debt | Fund Portfolio | LIBOR | Fund IV
Debt Instrument [Line Items]
Basis spread on variable rate		2.01%	1.90%
Maturity Date		2022-12
Subscription Line | Unsecured Debt | Fund V
Debt Instrument [Line Items]
Maturity Date		2022-05
Subscription Line | Unsecured Debt | Fund Portfolio | Fund V
Debt Instrument [Line Items]
Long-term debt, gross		$ 118,028	$ 250
Subscription Line | Unsecured Debt | Fund Portfolio | LIBOR | Fund V
Debt Instrument [Line Items]
Basis spread on variable rate		1.90%	1.60%
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]	$ 66,414	$ 138,400
Unsecured Line of Credit - Swapped | Line of Credit | Core Portfolio | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	5.32%	5.02%
Unsecured Line of Credit - Swapped | Line of Credit | Core Portfolio | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	[4]	3.65%	2.49%
Variable Rate Credit Facility [Member] | Unsecured Debt | Core Portfolio
Debt Instrument [Line Items]
Long-term debt, gross			$ 30,000
Variable Rate Credit Facility [Member] | Unsecured Debt | Core Portfolio | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate			2.55%

[1] Includes $110.5 million and $103.2 million, respectively, of variable-rate debt that is subject to interest cap agreements.

[2] Fixed-rate debt at December 31, 2021 and 2020 includes $0.0 million and $3.2 million, respectively of Core swaps that may be used to hedge debt instruments of the Funds.

[3] Includes $860.4 million and $969.7 million, respectively, of variable-rate debt that has been fixed with interest rate swap agreements as of the periods presented.

[4] At December 31, 2021, the stated rates ranged from LIBOR + 1.50% to LIBOR +1.90% for Core variable-rate debt; LIBOR + 2.75% for Fund III variable-rate debt; LIBOR +2.00% 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.