Supplemental Disclosures for the Statement of Consolidated Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Accrued capital expenditures and deferred lease costs	$ 38,366	$ 10,854	$ 11,276
Change in accrued dividends and discount on dividend reinvestments	(545)	(74,828)	71,267
Change in accrued share repurchases as part of an announced plan	(4,417)	3,140	1,276
Investment in consolidated joint venture	0	0	63,026
Cash and cash equivalents	13,545	4,571	7,382	$ 6,992
Restricted cash and escrows	1,841	1,463	1,373	1,212
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows	$ 15,386	$ 6,034	$ 8,755	$ 8,204