Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	May 31, 2012	May 31, 2012 Defendants	Sep. 30, 2011
Securities Class Action (Policeman's Annuity and Benefit Fund of Chicago) [Member]
Number of defendants		2
Agreement in principle settlement amount			$ 145.0
Settlement payment	145.0
Securities Class Action (Policeman's Annuity and Benefit Fund of Chicago) [Member] | Insurance claims - defense costs [Member]
Maximum possible loss	$ 23.2	23.2
Securities Class Action (Apollo Institutional Investors Group) [Member]
Number of plaintiffs		3
Adoma Wage and Hour Class Action [Member]
Number of current and former employees		1,500
Shareholder Derivative Actions and Demand Letters [Member]
Number of shareholders		2
Number of lawsuits		2