Related Parties - Additional Information (Detail) (Director, USD $) In Millions, unless otherwise specified	12 Months Ended
Sep. 30, 2011
Director
Related Party Transaction [Line Items]
Total operating revenues from related parties	$ 172

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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