Investments in Partnerships - Summary of Equity Investments (Detail) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Total assets		$ 755,675	$ 763,870
Investments in real estate, at cost:
Operating properties		563,525	612,689
Construction in progress		334,579	293,102
Total investments in real estate		898,104	905,791
Accumulated depreciation		(200,286)	(202,424)
Net investments in real estate		697,818	703,367
Cash and cash equivalents		26,391	26,158
Deferred costs and other assets, net		31,466	34,345
Total assets		755,675	763,870
LIABILITIES AND PARTNERS’ INVESTMENT:
Mortgage loans payable, net		512,772	513,139
Long Term Debt Equity Method Investment, net		247,517	0
Other liabilities		36,359	37,971
Total liabilities		796,648	551,110
Net investment		(40,973)	212,760
Partners’ share		(20,396)	106,886
PREIT’s share		(20,577)	105,874
Excess investment	[1]	13,870	13,081
Net investments and advances		(6,707)	118,955
Investment in partnerships, at equity		90,188	216,823
Distributions in excess of partnership investments		$ (96,895)	$ (97,868)

[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.”