Summarized Statements of Operations for Unconsolidated Investments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Investments in and Advances to Affiliates [Line Items]
Total expenses	$ 28,998	$ 32,119
Net loss	(2,480)	(880)
Statements Of Operations
Investments in and Advances to Affiliates [Line Items]
Total expenses	332	248
Net loss	$ (332)	$ (248)