Summary of Significant Accounting Policies, Equity Ownership (Details)	Sep. 30, 2011
Enogex Holdings [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	86.70%
Atoka [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	50.00%