Investments in Unconsolidated Joint Ventures - Combined Condensed Statements of Operations of Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Leasing revenue									$ 740,323	$ 858,874	$ 883,996
Total revenues	$ 194,643	$ 185,844	$ 178,587	$ 226,952	$ 241,841	$ 231,127	$ 227,972	$ 226,522	786,026	927,462	960,351
Expenses:
Leasing expense									25,191	29,611
Interest expense									75,550	138,254	182,962
Depreciation and amortization									319,619	330,726	327,436
Total expenses									773,487	859,918	934,931
Loss on sale or write down of assets, net									(68,112)	(11,909)	(31,825)
Net (loss) income									(245,462)	102,554	68,972
Company's equity in net loss									(27,038)	48,508	71,773
Other
Revenues:
Revenues									22,242	27,879	32,875
Shopping center and operating expenses
Expenses:
Operating expenses									257,212	271,547	277,470
Joint venture
Expenses:
Company's equity in net loss									(27,038)	48,508	71,773
Joint venture | PPR Portfolio
Expenses:
Loss on sale or write down of assets, net									(120)	(452)	(140)
Company's equity in net loss									(10,371)	(590)	(16)
Joint venture | Other Joint Ventures
Expenses:
Loss on sale or write down of assets, net									157	(380)	14,471
Company's equity in net loss									(16,667)	49,098	71,789
Joint venture | PPR Portfolio
Revenues:
Leasing revenue									171,505	187,789	186,924
Total revenues									172,119	189,387	187,829
Expenses:
Leasing expense									1,325	1,598
Interest expense									64,460	67,354	67,117
Depreciation and amortization									102,788	100,490	97,885
Total expenses									205,591	206,970	204,285
Net (loss) income									(33,592)	(18,035)	(16,596)
Joint venture | PPR Portfolio | Other
Revenues:
Revenues									614	1,598	905
Joint venture | PPR Portfolio | Shopping center and operating expenses
Expenses:
Operating expenses									37,018	37,528	39,283
Joint venture | Other Joint Ventures
Revenues:
Leasing revenue									633,357	712,860	727,328
Total revenues									651,796	762,044	768,748
Expenses:
Leasing expense									4,173	6,695
Interest expense									151,857	150,111	145,915
Depreciation and amortization									285,948	273,565	248,778
Total expenses									682,117	680,969	641,345
Net (loss) income									(30,164)	80,695	141,874
Joint venture | Other Joint Ventures | Other
Revenues:
Revenues									18,439	49,184	41,420
Joint venture | Other Joint Ventures | Shopping center and operating expenses
Expenses:
Operating expenses									240,139	250,598	246,652
Joint venture | Total
Revenues:
Leasing revenue									804,862	900,649	914,252
Total revenues									823,915	951,431	956,577
Expenses:
Leasing expense									5,498	8,293
Interest expense									216,317	217,465	213,032
Depreciation and amortization									388,736	374,055	346,663
Total expenses									887,708	887,939	845,630
Loss on sale or write down of assets, net									37	(832)	14,331
Net (loss) income									(63,756)	62,660	125,278
Joint venture | Total | Other
Revenues:
Revenues									19,053	50,782	42,325
Joint venture | Total | Shopping center and operating expenses
Expenses:
Operating expenses									$ 277,157	$ 288,126	285,935
Affiliated entity | Northwestern Mutual Life (NML)
Expenses:
Interest expense											$ 20,197