Reportable Segments (Net Income (Loss) Reconciliation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation from Segment Totals to Consolidated
Gain on sale of third party management and leasing business	$ 0	$ (4,577)	$ (7,459)
Interest expense	(185)	(520)	(1,985)
Reimbursed Expenses	(3,652)	(5,215)	(7,063)
Gains (Losses) on Extinguishment of Debt			(94)
Dividends, Preferred Stock	(2,955)	(10,008)	(12,907)
Net income available to common stockholders	45,519	109,097	32,821
Total Assets	2,667,330	2,273,206
Office
Reconciliation from Segment Totals to Consolidated
Net operating income	206,551	122,503	80,907
Fee income	0	0	0
Sales less costs of sales	0	0	0
Other income	0	0	0
Gain on sale of third party management and leasing business	0	0	0
Gain on sale of third party management and leasing	0		0
Interest expense	0	0	0
Third party management and leasing expenses	0	0	0
Reimbursed Expenses	0	0	0
Separation expenses	0	0	0
Interest expense			0
Gains (Losses) on Extinguishment of Debt			0
Reimbursed expenses	0	0	0
Dividends, Preferred Stock	0	0	0
Funds from operations available to common stockholders	206,551	122,503	80,907
Total Assets	2,576,449	2,163,123	736,867
Retail
Reconciliation from Segment Totals to Consolidated
Net operating income	4,479	13,278	29,429
Fee income	0	0	0
Sales less costs of sales	0	0	0
Other income	0	0	0
Gain on sale of third party management and leasing business	0	0	0
Gain on sale of third party management and leasing	0		0
Interest expense	0	0	0
Third party management and leasing expenses	0	0	0
Reimbursed Expenses	0	0	0
Separation expenses	0	0	0
Interest expense			0
Gains (Losses) on Extinguishment of Debt			0
Reimbursed expenses	0	0	0
Dividends, Preferred Stock	0	0	0
Funds from operations available to common stockholders	4,479	13,278	29,429
Total Assets	5,587	18,112	151,417
Land
Reconciliation from Segment Totals to Consolidated
Net operating income	0	0	0
Fee income	3,868	1,273	4,915
Sales less costs of sales	0	0	0
Other income	0	0	0
Gain on sale of third party management and leasing business	0	0	0
Gain on sale of third party management and leasing	0		0
Interest expense	0	0	0
Third party management and leasing expenses	0	0	0
Reimbursed Expenses	0	0	0
Separation expenses	0	0	0
Interest expense			0
Gains (Losses) on Extinguishment of Debt			0
Reimbursed expenses	0	0	0
Dividends, Preferred Stock	0	0	0
Funds from operations available to common stockholders	3,868	1,273	4,915
Total Assets	34,799	47,235	50,520
Third Party Management and Leasing
Reconciliation from Segment Totals to Consolidated
Net operating income		0	0
Fee income		0	0
Sales less costs of sales		76	16,365
Other income		0	0
Gain on sale of third party management and leasing business		4,576	7,459
Gain on sale of third party management and leasing		(97)	(13,675)
Interest expense		0	0
Third party management and leasing expenses		0	0
Reimbursed Expenses		0	0
Separation expenses		0	0
Interest expense			0
Gains (Losses) on Extinguishment of Debt			0
Reimbursed expenses		0	0
Dividends, Preferred Stock		0	0
Funds from operations available to common stockholders		4,555	10,149
Total Assets			0
Other
Reconciliation from Segment Totals to Consolidated
Net operating income	4,643	2,299	121
Fee income	42	191	309
Sales less costs of sales	12,519	10,891	17,797
Other income	5,404	3,528	5,153
Gain on sale of third party management and leasing business	(3)	0	0
Gain on sale of third party management and leasing	(2)	0	0
Interest expense	(210)	(520)	(1,985)
Third party management and leasing expenses	(19,784)	(21,940)	(23,208)
Reimbursed Expenses	(3,652)	(5,215)	(7,063)
Separation expenses	(36,474)	(29,672)	(28,154)
Interest expense			(488)
Gains (Losses) on Extinguishment of Debt			(94)
Reimbursed expenses	(5,692)	(11,373)	(8,389)
Dividends, Preferred Stock	(6,485)	(12,664)	(12,907)
Funds from operations available to common stockholders	(49,694)	(64,475)	(58,908)
Total Assets	50,495	44,736	185,438
Total
Reconciliation from Segment Totals to Consolidated
Net operating income	215,673	138,080	110,457
Fee income	3,910	1,464	5,224
Sales less costs of sales	12,519	10,967	34,162
Other income	5,404	3,528	5,153
Gain on sale of third party management and leasing business	(3)	4,576	7,459
Gain on sale of third party management and leasing	(2)	(97)	(13,675)
Interest expense	(210)	(520)	(1,985)
Third party management and leasing expenses	(19,784)	(21,940)	(23,208)
Reimbursed Expenses	(3,652)	(5,215)	(7,063)
Separation expenses	(36,474)	(29,672)	(28,154)
Interest expense			(488)
Gains (Losses) on Extinguishment of Debt			(94)
Reimbursed expenses	(5,692)	(11,373)	(8,389)
Dividends, Preferred Stock	(6,485)	(12,664)	(12,907)
Funds from operations available to common stockholders	165,204	77,134	66,492
Real estate depreciation and amortization, including Company's share of joint ventures	(151,066)	(92,041)	(62,043)
Gain on sale of depreciated investment properties, including Company's share of joint ventures			(11,748)
Non-controlling interest related to the sale of depreciated properties	31,955	127,401	41,944
Other adjustments			(1,824)
Noncontrolling Interest Related to Gain on Sale of Depreciated Investment Properties	(574)	(3,397)
Net income available to common stockholders	45,519	109,097	32,821
Total Assets	$ 2,667,330	$ 2,273,206	$ 1,124,242