Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2014

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 approximates their fair values, except for the following (in thousands):     

	December 31,
	2014			2013
	Carrying Amount		Fair Value	Carrying Amount		Fair Value
Financial assets:
Notes receivable	$	12,132	11,980	$	11,960	11,600
Financial liabilities:
Notes payable	$	1,946,357	2,116,000	$	1,779,697	1,936,400
Unsecured credit facilities	$	75,000	75,000	$	75,000	75,400

Fair Value, Interest rate ranges [Table Text Block]

he following interest rates were used by the Company to estimate the fair value of its financial instruments:

	December 31,
	2014		2013
	Low	High	Low	High
Notes receivable	7.4%	7.4%	7.8%	7.8%
Notes payable	0.9%	3.4%	3.0%	3.5%
Unsecured credit facilities	1.3%	1.3%	1.4%	1.4%

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

The following table presents the placement in the fair value hierarchy of assets and liabilities that are measured at fair value on a recurring basis (in thousands):

	Fair Value Measurements as of December 31, 2014
				Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs		Significant Unobservable Inputs
	Balance			(Level 1)	(Level 2)		(Level 3)
Assets:
Trading securities held in trust	$	28,134		28,134	—		—
Interest rate derivatives	—			—	—		—
Total	$	28,134		28,134	—		—
Liabilities:
Interest rate derivatives	$	(18,794	)	—	(18,794	)	—

	Fair Value Measurements as of December 31, 2013
				Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs		Significant Unobservable Inputs
	Balance			(Level 1)	(Level 2)		(Level 3)
Assets:
Trading securities held in trust	$	26,681		26,681	—		—
Interest rate derivatives	35,237			—	35,237		—
Total	61,918			26,681	35,237		—
Liabilities:
Interest rate derivatives	$	(34	)	—	(34	)	—

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

	Fair Value Measurements during the
	year ended December 31, 2014
			Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs	Significant Unobservable Inputs	Total Gains (Losses)
Assets:	Balance		(Level 1)	(Level 2)	(Level 3)
Long-lived asset held and used
Land	$	397	—	—	397	(175	)

	Fair Value Measurements during the
	year ended December 31, 2013
			Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs	Significant Unobservable Inputs	Total Gains (Losses)
Assets:	Balance		(Level 1)	(Level 2)	(Level 3)
Long-lived asset held and used
Operating and development properties	$	4,686	—	—	4,686	(6,000	)

Fair Value Inputs, Assets, Quantitative Information [Table Text Block]

During the year ended December 31, 2013, the Company recognized a $6 million impairment on a single operating property as a result of an unoccupied anchor declaring bankruptcy, and the inability of the Company, at that time, to re-lease the anchor space. The following are the key inputs used in determining the fair value of real estate measured using Level 3 inputs during the year ended December 31, 2013:

	2013
Overall cap rates	8.0%
Rental growth rates	0.0%
Discount rates	9.0%
Terminal cap rates	8.5%