Significant Accounting Policies and Practices and Recent Accounting Pronouncements - Proven and Unproven Oil and Gas Properties (Details) (USD $) In Millions, unless otherwise specified	7 Months Ended	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2013 Gas Gathering Assets	Sep. 30, 2013 EXCO/HGI JV HGI Energy Holdings, LLC	Sep. 30, 2013 Unproved Oil and Natural Gas Properties and Development Costs Not Being Amortized EXCO/HGI JV	Feb. 14, 2013 Unproved Oil and Natural Gas Properties and Development Costs Not Being Amortized EXCO/HGI JV
Reserve Quantities [Line Items]
Capitalized Costs, Unproved Properties							$ 36.5	$ 48.5
Impairment of unproved oil and natural gas properties	10.3
Unamortized costs exceed ceiling limitations						222.0
Impairment of proved oil and natural gas properties		$ 54.3	$ 0	$ 0
Property, Plant and Equipment, Estimated Useful Lives					14 years