Investments in Partnerships - Summary of Equity Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Investments in real estate, at cost:
Operating properties	$ 814,056	$ 824,328
Construction in progress	33,319	20,632
Total investments in real estate	847,375	844,960
Accumulated depreciation	(230,320)	(224,641)
Net investments in real estate	617,055	620,319
Cash and cash equivalents	34,698	28,060
Deferred costs and other assets, net	155,057	161,465
Total assets	806,810	809,844
LIABILITIES AND PARTNERS’ INVESTMENT:
Mortgage loans payable, net	488,803	491,119
FDP Term Loan, net	201,000	201,000
Partnership Loan	106,066	100,000
Other liabilities	133,396	132,715
Total liabilities	929,265	924,834
Net investment	(122,455)	(114,990)
Partners’ share	(62,672)	(59,080)
PREIT’s share	(59,783)	(55,910)
Excess investment	6,333	6,390
Net investments and advances	(53,450)	(49,520)
Investment in partnerships, at equity	21,597	27,066
Distributions in excess of partnership investments	$ (75,047)	$ (76,586)