Consolidated Balance Sheets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Document Period End Date	Dec. 31, 2019
Assets
Real estate investments, net of accumulated depreciation of $989,254 and $883,174 at December 31, 2019 and 2018, respectively	$ 5,197,308	$ 5,024,057
Land held for development	28,080	34,177
Property under development	36,756	287,546
Operating Lease, Right-of-Use Asset	211,187	0
Mortgage Notes and Related Accrued Interest Receivable, Net	357,391	517,467
Investment in direct financing leases, net	0	20,558
Investment in joint ventures	34,317	34,486
Cash and cash equivalents	528,763	5,872
Restricted cash	2,677	12,635
Accounts receivable, net	86,858	98,369
Other assets	94,174	96,223
Total assets	6,577,511	6,131,390
Liabilities:
Accounts payable and accrued liabilities	122,939	168,463
Operating Lease, Liability	235,650	0
Dividends Payable, Current	29,424	26,765
Preferred dividends payable	6,034	6,034
Unearned rents and interest	74,829	79,051
Debt	3,102,830	2,986,054
Total liabilities	3,571,706	3,266,367
Equity:
Common Shares, $.01 par value; 100,000,000 shares authorized; and 81,588,489 and 77,226,443 shares issued at December 31, 2019 and 2018, respectively	816	772
Preferred shares, $.01 par value; 25,000,000 shares authorized:
Additional paid-in-capital	3,834,858	3,504,494
Treasury shares at cost: 3,125,569 and 2,878,587 common shares at December 31, 2019 and 2018, respectively	(147,435)	(130,728)
Accumulated other comprehensive income	7,275	12,085
Distributions in excess of net income	(689,857)	(521,748)
Equity	3,005,805	2,865,023
Total liabilities and equity	6,577,511	6,131,390
Series C Preferred Shares [Member]
Preferred shares, $.01 par value; 25,000,000 shares authorized:
Preferred shares	54	54
Series E Preferred Shares [Member]
Preferred shares, $.01 par value; 25,000,000 shares authorized:
Preferred shares	34	34
Series G Preferred Stock [Member]
Preferred shares, $.01 par value; 25,000,000 shares authorized:
Preferred shares	$ 60	$ 60