Fair Value Disclosures (Assets and Liabilities Measured At Fair Value On A Recurring Basis) (Details) $ in Thousands		6 Months Ended	9 Months Ended	12 Months Ended
		Jun. 30, 2021	Sep. 30, 2021 USD ($) years	Dec. 31, 2020 USD ($) years
Long-term Debt			$ 2,684,063	$ 3,694,443
Derivative Liability, Fair Value, Gross Liability			(4,400)	(14,000)
Financing Receivable, after Allowance for Credit Loss, Current			369,134	365,628
Real Estate Investment Property, Net			4,800,561	4,851,302
Operating Lease, Right-of-Use Asset			175,987	163,766
Investment in joint ventures			38,729	28,208
Other assets			$ 64,639	$ 70,223
Number of impaired properties			2
Right-of-Use Assets, Operating Lease [Member]
Number of impaired properties | years				2
Fair Value, Recurring [Member] | Cross Currency Swaps [Member]
Derivative Liability, Fair Value, Gross Liability	[1]		$ (3,781)	$ (4,271)
Fair Value, Recurring [Member] | Cross Currency Swaps [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Liability, Fair Value, Gross Liability	[1]		(3,781)	(4,271)
Fair Value, Recurring [Member] | Interest Rate Swap [Member]
Derivative Liability, Fair Value, Gross Liability	[1]		(610)	(9,723)
Fair Value, Recurring [Member] | Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Liability, Fair Value, Gross Liability	[1]		(610)	(9,723)
Fair Value, Nonrecurring [Member]
Real Estate Investment Property, Net			6,956	39,544
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Real Estate Investment Property, Net			$ 6,956	$ 29,684
Number of impaired properties | years			2	6
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Real Estate Investment Property, Net			$ 0	$ 9,860
Operating Lease, Right-of-Use Asset				12,953
Investment in joint ventures				771
Other assets				$ 0
Number of impaired properties | years				3
Variable Rate Converted to Fixed Rate [Member]
Long-term Debt			25,000	$ 425,000
Fixed Rate Mortgage Notes Receivable Member
Financing Receivable, after Allowance for Credit Loss, Current			$ 369,100	$ 365,600
Mortgage Receivable Weighted Average Interest Rate			9.02%	9.03%
Receivable Interest Rate Stated Percentage Rate Range Minimum			7.01%	7.01%
Receivable Interest Rate Stated Percentage Rate Range Maximum			11.96%	11.78%
Notes Receivable, Fair Value Disclosure			$ 406,000	$ 394,000
Weighted Average Market Rate Used As Discount Factor To Determine Fair Value Of Notes			7.80%	8.11%
Fixed Rate Mortgage Notes Receivable Member | Minimum [Member]
market rate used as discount factor to determine fair value of notes			7.25%	7.50%
Fixed Rate Mortgage Notes Receivable Member | Maximum [Member]
market rate used as discount factor to determine fair value of notes			9.00%	10.00%
Variable Rate Debt Member
Long-term Debt			$ 25,000	$ 1,000,000
Long-term Debt, Weighted Average Interest Rate, at Point in Time			0.13%	2.23%
Fixed Rate Debt Member
Long-term Debt			$ 2,690,000	$ 2,720,000
Long-term Debt, Weighted Average Interest Rate, at Point in Time			4.54%	4.70%
Long-term Debt, Fair Value			$ 2,860,000	$ 2,690,000
Weighted Average Market Rate Used As Discount Factor To Determine Fair Value Of Debt		4.70%	3.04%
Fixed Rate Debt Member | Minimum [Member]
market rate used as discount factor to determine fair value of debt		4.09%	1.91%
Fixed Rate Debt Member | Maximum [Member]
market rate used as discount factor to determine fair value of debt		5.81%	4.56%

[1] Included in "Accounts payable and accrued liabilities" in the accompanying consolidated balance sheets.