Investments in Partnerships - Summary of Equity Investments (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Total assets		$ 754,043	$ 668,020
Investments in real estate, at cost:
Operating properties		612,623	649,960
Construction in progress		261,735	160,699
Total investments in real estate		874,358	810,659
Accumulated depreciation		(201,964)	(207,987)
Net investments in real estate		672,394	602,672
Cash and cash equivalents		47,431	27,643
Deferred costs and other assets, net		34,218	37,705
Total assets		754,043	668,020
LIABILITIES AND PARTNERS’ INVESTMENT:
Mortgage loans payable, net		440,315	445,224
Other liabilities		54,079	23,945
Total liabilities		494,394	469,169
Net investment		259,649	198,851
Partners’ share		130,627	101,045
PREIT’s share		129,022	97,806
Excess investment	[1]	12,107	8,969
Net investments and advances		141,129	106,775
Investment in partnerships, at equity		201,000	168,608
Distributions in excess of partnership investments		$ (59,871)	$ (61,833)

[1] Excess investment represents the unamortized difference between our investment and our share of the equity in the underlying net investment in the unconsolidated partnerships. The excess investment is amortized over the life of the properties, and the amortization is included in “Equity in income of partnerships.”