Deferred Charges Other Assets (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 31, 2019
Leasing costs	$ 59,552	$ 52,507
Accumulated amortization	(9,904)	(7,577)
Deferred Costs, Leasing, Net	49,648	44,930
In-place leases, net	1,766	3,122
Investment in Simon common shares (Note 17)		48,738
Revolving credit facilities' deferred financing costs, net	8,229	4,374
Insurance deposit (Note 17)	11,213	10,121
Deposits	956	975
Prepaid expenses	6,091	6,671
Deferred tax asset, net	5,032	6,380
Other, net	9,724	9,825
Deferred Costs and Other Assets	92,659	135,136
Gain on Simon common share conversion (Note 7)			$ (11,613)
SPG Common Shares [Member]
Conversion of Simon Property Group Limited Partnership Units to SPG Common Stock			340,124
Gain on Simon common share conversion (Note 7)			$ 11,600
Available-For-Sale Securities Held	0	290,124
Simon Property Group Common Shares Sold		300,000		290,124
SPG Common Shares Average Sales Price		$ 182.37		$ 179.52