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The cash outflow due to repaying amounts of principal.

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Gross amount of debt extinguished.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The cash inflow from borrowings to finance the cost of construction.

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Debt - Mortgage and construction loans payable transactions occurred (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Long Term Debt Transactions [Roll Forward]
Balance, December 31, 2018	$ 3,397,850	$ 3,027,599
Additions:
Draws under advancing construction notes payable	31,611	100,882	$ 40,170
Deductions:
Balance, December 31, 2019	3,027,599
Gain from extinguishment of debt	20,992	7,867	$ 0
Mortgage loans payable
Long Term Debt Transactions [Roll Forward]
Balance, December 31, 2018	759,526	795,030
Deductions:
Pay-off and extinguishment of mortgage notes payable	(27,381)
Scheduled repayments of principal	(8,123)
Balance, December 31, 2019	795,030
Construction loans payable
Long Term Debt Transactions [Roll Forward]
Balance, December 31, 2018	0	$ 22,207
Additions:
Draws under advancing construction notes payable	31,611
Deductions:
Pay-off of debt	(53,818)
Balance, December 31, 2019	$ 22,207