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This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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The number of derivative instruments of a particular derivative asset or group of derivative assets held by the entity.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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FAIR VALUE MEASUREMENTS - Recurring Basis (Details)	12 Months Ended
FAIR VALUE MEASUREMENTS - Recurring Basis (Details)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) derivative_instrument	Dec. 31, 2014 USD ($)
Liabilities:
Interest rate swaps		$ 434,000
Net realized gains and losses on sale of available-for-sale securities	$ 0	16,560,000	$ 0
Proceeds from sale of available-for-sale securities		20,755,000
Fair value of mortgage and other indebtedness	4,737,077,000	4,945,622,000
Mortgage and other indebtedness	$ 4,465,294,000	4,710,628,000
Common Stock
Liabilities:
Adjusted cost		$ 4,195,000
Interest Rate Swap \| Fair Value, Measurements, Recurring
Liabilities:
Number of instruments held \| derivative_instrument		4
Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Interest rate swaps		$ 0
Significant Other Observable Inputs (Level 2)
Liabilities:
Interest rate swaps		434,000
Significant Unobservable Inputs (Level 3)
Liabilities:
Interest rate swaps		$ 0