Net Gain (Loss) on Disposition of Partial Interests in Rental Properties (Details Textual) (USD $)	11 Months Ended		12 Months Ended		11 Months Ended	12 Months Ended			11 Months Ended	12 Months Ended			11 Months Ended	12 Months Ended			1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2013	Jan. 31, 2012	Dec. 31, 2013 QIC Joint Venture [Member] properties property	Jan. 31, 2013 QIC Joint Venture [Member]	Jan. 31, 2012 QIC Joint Venture [Member]	Sep. 30, 2013 QIC Joint Venture [Member] properties	Dec. 31, 2013 New York Retail Joint Venture [Member]	Jan. 31, 2013 New York Retail Joint Venture [Member]	Jan. 31, 2012 New York Retail Joint Venture [Member]	Mar. 31, 2011 New York Retail Joint Venture [Member] properties	Dec. 31, 2013 Stonecrest Mall Joint Venture [Member]	Jan. 31, 2013 Stonecrest Mall Joint Venture [Member]	Jan. 31, 2012 Stonecrest Mall Joint Venture [Member]	Oct. 31, 2011 Stonecrest Mall Joint Venture [Member]	Dec. 31, 2011 Annex building adjacent to the Dallas Wilson Building [Member] rentals	Dec. 31, 2013 Annex building adjacent to the Dallas Wilson Building [Member]	Jan. 31, 2013 Annex building adjacent to the Dallas Wilson Building [Member]	Jan. 31, 2012 Annex building adjacent to the Dallas Wilson Building [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of ownership sold					49.00%							49.00%				49.00%
Number of properties held by newly formed joint venture					8							15
Number of fully consolidated assets								7
Number of equity method investments					1
Debt assumed by the outside partner					$ 477,100,000							$ 244,952,000				$ 49,464,000
Proceeds received, net of transaction costs					421,700,000
Cash proceeds					187,700,000
Net gain on disposition of partial interests in rental properties	496,092,000	0	0	17,665,000	381,627,000	0	0		114,465,000	0	9,561,000		0	0	5,849,000			0	0	2,255,000
Gain on disposition of partial interests in equity method investments	27,080,000		0	0	27,080,000
Number of regional retail malls in which Company acquired noncontrolling interests					2
Acquisitions of noncontrolling interests	98,687,000		27,335,000	0	92,400,000
Proceeds in the form of loan from the joint venture											178,286,000
Outside partner's minimum initial investment requirement											20.00%
Transaction costs											11,776,000
Participation payment made to the ground lessor of two properties											5,779,000
Deferred gain										114,465,000
Contingent consideration													3,750,000
Number of units sold																	8
Proceeds from sale of buildings																	$ 2,800,000
Remaining units wholly-owned by the Company																	135