Special Items - Additional Information (Detail) (Mr. J. Mike Walker [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Dec. 31, 2011
Mr. J. Mike Walker [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Pre-tax expense	$ 4.7
Salary and bonus including payroll taxes	3.3
Pre-tax non-cash expenses	$ 1.4

The aggregate amount of expenditures for salaries, wages, profit sharing and incentive compensation, and other employee benefits, including equity-based compensation, and pension and other postretirement benefit expense.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.4)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration