Income Taxes (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Valuation Allowance
Valuation allowance	$ 232.7	$ 385.8
Tax benefit from the release of a valuation allowance against a deferred tax asset in a Luxembourg	129.5
Net operating losses in Luxembourg subsidiaries
Valuation Allowance
Valuation allowance	225.5	379.6
Number of Luxembourg domiciled subsidiaries related to which tax benefit is recorded from release of valuation allowances against deferred tax assets	2
Term of longest dated note of notes having staggered maturity dates (in years)	30
U.S. losses and other federal deferred tax benefits
Valuation Allowance
Valuation allowance	$ 6.9	$ 6.2