Summary of Outstanding Notes Receivable from Affiliate Balances and Related Interest Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Investments in and Advances to Affiliates [Line Items]
Notes receivable from affiliate		$ 21,769
Interest income	$ 3	$ 59

For an unclassified balance sheet, amount of receivables due from an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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+ Details