Supplemental Cash Flow Information of the Company (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Significant Noncash Transactions [Line Items]
Interest Paid, Net	$ 54,747	$ 58,944	$ 65,157
Capital Expenditures Incurred but Not yet Paid	109,715	77,091	73,482
Tenant improvements funded directly by tenants to third parties	13,837	42,906	7,633
Noncash or Part Noncash Acquisition, Debt Assumed	0	0	95,496
Noncash or Part Noncash Acquisition, Other Liabilities Assumed	6,254	14,917	1,811
Release of Holdback Funds to Third Party	9,279	0	0
Noncash or Part Noncash Acquisition, Land Contributed, Net of Liabilities Assumed	0	0	(4,885)
Common Stockholders And Unitholders Dividends And Distributions Declared But Not Paid	(33,336)	(31,243)	(29,378)
Preferred Stockholders And Unitholders Dividends And Distributions Declared But Not Paid	1,656	1,656	1,694
purchase price, value of shares issued to acquire land	0	21,631	0
Conversion of Stock, Amount Converted	$ 1,223	$ 28	$ 450