Significant Accounting Policies and Practices and Recent Accounting Pronouncements - Overhead Reimbursement Fees (Details) (HGI Energy Holdings, LLC, Compass, USD $) In Millions, unless otherwise specified	7 Months Ended	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2014
HGI Energy Holdings, LLC | Compass
Subsidiary or Equity Method Investee [Line Items]
Results of Operations, General and Administrative Related to Oil and Gas Producing Activities	$ 4.3	$ 7.5