Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

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:



	December 31,
	2017			2016
(in thousands)	Carrying Amount		Fair Value	Carrying Amount		Fair Value
Financial assets:
Notes receivable	$	15,803	15,660	$	10,481	10,380
Financial liabilities:
Notes payable	$	2,971,715	3,058,044	$	1,363,925	1,435,000
Unsecured credit facilities	$	623,262	625,000	$	278,495	279,700

Fair Value, Interest rate ranges [Table Text Block]

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



	December 31,
	2017		2016
	Low	High	Low	High
Notes receivable	3.8%	7.8%	7.2%	7.2%
Notes payable	3.0%	3.9%	2.9%	3.9%
Unsecured credit facilities	2.0%	3.0%	1.5%	1.6%

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:



	Fair Value Measurements as of December 31, 2017
				Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs		Significant Unobservable Inputs
(in thousands)	Balance			(Level 1)	(Level 2)		(Level 3)
Assets:
Trading securities held in trust	$	31,662		31,662	—		—
Available-for-sale securities	9,974			—	9,974		—
Interest rate derivatives	14,515			—	14,515		—
Total	$	56,151		31,662	24,489		—
Liabilities:
Interest rate derivatives	$	(177	)	—	(177	)	—



	Fair Value Measurements as of December 31, 2016
				Quoted Prices in Active Markets for Identical Assets	Significant Other Observable Inputs		Significant Unobservable Inputs
(in thousands)	Balance			(Level 1)	(Level 2)		(Level 3)
Assets:
Trading securities held in trust	$	28,588		28,588	—		—
Available-for-sale securities	7,420			—	7,420		—
Interest rate derivatives	11,622			—	11,622		—
Total	$	47,630		28,588	19,042		—
Liabilities:
Interest rate derivatives	$	(580	)	—	(580	)	—