This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
-Paragraph 1
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- Definition

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

+ References

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-Name Accounting Standards Codification
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-SubTopic 10
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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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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Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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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) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) derivative_instrument	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized gain on available-for-sale securities, reclassified		$ 16,560
Proceeds from sale of available-for-sale securities	$ 20,755	20,755
Fair value of mortgage and other indebtedness	$ 4,737,077		$ 4,199,357
Interest Rate Swap \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of instruments held \| derivative_instrument	4
Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Adjusted cost		$ 4,195