Impairment Charges and Impairment of Joint Venture Investments - Impairment Charges on Consolidated Assets (Detail) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Investment Securities [Line Items]
Land held for development			$ 10,100,000	$ 54,200,000	$ 54,300,000
Undeveloped land			20,100,000	9,000,000	30,500,000
Assets marketed for sale			75,200,000	4,700,000	0
Total continuing operations			105,395,000	67,912,000	84,855,000
Sold assets			21,100,000	57,900,000	51,800,000
Assets formerly occupied by Mervyns			0	0	35,300,000
Total discontinued operations			21,076,000	57,932,000	87,045,000
Joint venture investments			26,671,000	2,921,000	227,000
Total impairment charges	$ 20,600,000	$ 47,400,000	$ 153,142,000	$ 128,765,000	$ 172,127,000