Temporary Equity - Additional Information (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Apr. 01, 2012	Aug. 05, 2011	May 13, 2011
Temporary Equity [Line Items]
Aggregate gross proceeds at issuance				$ 400.0
Temporary equity liquidation preference, minimum threshold rate					150.00%
Preferred stock, dividend rate	8.00%
Preferred stock, paid in kind dividend rate		0.00%	2.00%		4.00%
Bifurcation of embedded derivative upon issuance				(103.3)
Carrying value of Preferred Stock	329.4	319.2		282.6
Issuance costs				(14.1)
Temporary equity discount upon issuance				117.4
Temporary equity, expected contractual term					7 years
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Temporary equity, shares issued				120	280
Aggregate gross proceeds at issuance					280.0
Preferred stock conversion price (in dollars per share)					$ 6.50
Shares converted at conversion	6
Bifurcation of embedded derivative upon issuance					(85.7)
Carrying value of Preferred Stock	224.4
Issuance costs					(11.1)
Common Stock
Temporary Equity [Line Items]
Shares issued at conversion	852
Series A-2 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Aggregate gross proceeds at issuance				120.0
Preferred stock conversion price (in dollars per share)				$ 7.00
Bifurcation of embedded derivative upon issuance				(17.6)
Carrying value of Preferred Stock	104.9
Issuance costs				(3.0)
NAV Threshold 1
Temporary Equity [Line Items]
Preferred stock, paid in kind dividend rate					4.00%
NAV Threshold 2
Temporary Equity [Line Items]
Preferred stock, paid in kind dividend rate					2.00%
NAV Threshold 3
Temporary Equity [Line Items]
Preferred stock, paid in kind dividend rate					0.00%
Inclusive of Issuance Costs
Temporary Equity [Line Items]
Carrying value of Preferred Stock				296.7
EXCO/HGI JV | Class B Redeemable Common Units [Member]
Temporary Equity [Line Items]
Carrying value of Preferred Stock	$ 0.1