Summarized Financial Information for Unconsolidated Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012	Dec. 31, 2011
Investment In Unconsolidated Affiliates [Line Items]
Investment in real estate	$ 370,935		$ 370,647
Cash and cash equivalents	168,652		165,980		165,689	162,391
Other assets	22,475		20,639
Total assets	651,321		645,521
Accounts payable and other liabilities	47,345		42,352
Total liabilities and equity	651,321		645,521
Other Affiliates
Investment In Unconsolidated Affiliates [Line Items]
Investment in real estate	12,381		12,381
Cash and cash equivalents	18,098		18,523
Other assets	357		130
Total assets	30,836		31,034
Accounts payable and other liabilities	827		761
Equity	30,009	[1]	30,273	[1]
Total liabilities and equity	$ 30,836		$ 31,034

[1] The majority of the equity in unconsolidated investments relates to ALP Liquidating Trust ("The Trust). In 2008, the Company wrote-off its investment in the Trust as a result of the Trust reserving its assets to satisfy potential claims and obligations in accordance with its publicly reported liquidation basis of accounting. Subsequently, the Trust changed its method of accounting to a going concern basis and reinstated its equity and stated it would report certain expenses as they are incurred. The Company has not recorded any additional equity income as a result of the trust's change in accounting.