Debt (Tables)

6 Months Ended

Jun. 30, 2014

Debt [Abstract]

Schedule of Debt [Table Text Block]

		Interest Rate at		Balance at
(Amounts in thousands)		June 30, 2014		June 30, 2014		December 31, 2013
Mortgages Payable:
	Fixed rate		4.48%	$	7,623,049	$	7,563,133
	Variable rate		2.31%		1,365,794		768,860
			4.15%	$	8,988,843	$	8,331,993
Unsecured Debt:
	Senior unsecured notes		4.88%	$	1,791,814	$	1,350,855
	Revolving credit facility debt		1.30%		88,138		295,870
			4.71%	$	1,879,952	$	1,646,725