Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping [Table Text Block]

All financial instruments of the Company are reflected in the accompanying Consolidated Balance Sheets at amounts which, in management's estimation, reasonably approximate their fair values, except for the following as of June 30, 2013 and December 31, 2012 (in thousands):

		2013			2012
		Carrying Amount	Fair Value		Carrying Amount	Fair Value
Financial assets:
Notes receivable	$	18,502	18,153	$	23,751	23,677
Financial liabilities:
Notes payable	$	1,767,124	1,924,578	$	1,771,891	2,000,000
Unsecured credit facilities	$	125,000	125,240	$	170,000	170,200

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

he following table presents the placement in the fair value hierarchy of assets and liabilities that are measured at fair value on a recurring basis as of June 30, 2013 and December 31, 2012 (in thousands):

		Fair Value Measurements as of June 30, 2013
				Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs		Significant Unobservable Inputs
Assets		Balance		(Level 1)	(Level 2)		(Level 3)
Trading securities held in trust	$	24,457		24,457	—		—
Interest rate derivatives		26,011		—	26,011		—
Total	$	50,468		24,457	26,011		—
Liabilities
Interest rate derivatives	$	(51	)	—	(51	)	—

		Fair Value Measurements as of December 31, 2012
				Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs		Significant Unobservable Inputs
Assets		Balance		(Level 1)	(Level 2)		(Level 3)
Trading securities held in trust	$	23,429		23,429	—		—
Interest rate derivatives		4,307		—	4,307		—
Total	$	27,736		23,429	4,307		—
Liabilities
Interest rate derivatives	$	(76	)	—	(76	)	—

Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Table Text Block]

The following table presents fair value measurements that were measured at fair value on a nonrecurring basis as of December 31, 2012 (in thousands):

		Fair Value Measurements as of December 31, 2012
			Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs	Significant Unobservable Inputs	Total Gains (Losses) (1)
Assets		Balance	(Level 1)	(Level 2)	(Level 3)
Long-lived assets held and used
Operating and development properties	$	49,673	—	—	49,673	(54,500	)

⁽¹⁾ Excludes impairments for properties sold during the year ended December 31, 2012.

Ranges Of Key Inputs Used In Determining The Fair Value Of Real Estate [Table Text Block]

The following are ranges of key inputs used in determining the fair value of real estate measured using Level 3 inputs as of December 31, 2012:

	2012
	Low		High
Overall cap rates	8.3	%	8.5	%
Rental growth rates	(8.3	)%	2.5	%
Discount rates	10.5	%	10.5	%
Terminal cap rates	8.8	%	8.8	%