Fair Value Of Financial Instruments (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes and debentures, carrying value	$ 1,694,764,000us-gaap_SeniorNotes	$ 1,483,813,000us-gaap_SeniorNotes
Notional amount of interest rate swap agreements	275,000,000
Interest rate cash flow hedge to be reclassified within next 12 months, net	3,800,000
Other comprehensive income (loss) - change in value of interest rate swaps	(2,461,000)
Interest expense reclassified from other comprehensive loss	1,100,000
Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term Loan	275,000,000
Derivative, fixed interest rate	1.72%
Fair value of interest rate swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Number of interest rate swap agreements	2
Fair value of interest rate swaps \| Fair value, measurements, recurring \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of interest rate swaps	0	0
Fair value of interest rate swaps \| Fair value, measurements, recurring \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of interest rate swaps	5,976,000	3,515,000
Fair value of interest rate swaps \| Fair value, measurements, recurring \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of interest rate swaps	0	0
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, carrying value	870,329,000	854,217,000
Senior notes and debentures, carrying value	1,694,764,000	1,483,813,000
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgages and notes payable, fair value	894,258,000	880,866,000
Senior notes and debentures, fair value	$ 1,814,913,000	$ 1,579,868,000

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Mortgages and Notes Payable, Fair Value Disclosure

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Senior Notes and Debentures, Fair Value Disclosure

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- Definition

Fixed interest rate related to the interest rate derivative.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Nominal or face amount used to calculate payments on the derivative liability.

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The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.

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The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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Number of interest rate derivative instruments held by the entity at the reporting date.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Including the current and noncurrent portions, the carrying value of notes payable which were initially due after one year or beyond the normal operating cycle, if longer, and which are not otherwise defined in the taxonomy.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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