Supplemental Disclosures for the Statement of Consolidated Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Accrued capital expenditures and deferred lease costs	$ 33,199	$ 16,380
Change in accrued dividends and discount on dividend reinvestments	(25,682)	(26,427)
Change in accrued share repurchases as part of an announced plan	(685)	0
Accrued stock issuance costs	26	0
Cash and cash equivalents	8,122	36,469	$ 7,331	$ 13,545
Restricted cash and escrows	1,578	1,769	1,883	1,841
Cash, cash equivalents, and restricted cash and escrows, beginning of period, as presented in the accompanying consolidated statement of cash flows	$ 9,700	$ 38,238	$ 9,214	$ 15,386