Investment in Unconsolidated Affiliates Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended				9 Months Ended				3 Months Ended		9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Operating Costs Charged [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Operating Costs Charged [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Operating Costs Charged [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Operating Costs Charged [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Natural Gas Transportation [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Natural Gas Transportation [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Natural Gas Transportation [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Natural Gas Transportation [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Natural Gas Storage [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Natural Gas Storage [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Natural Gas Storage [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Natural Gas Storage [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Natural Gas Purchases [Member] Enable Midstream Partners [Member] OG&E [Member]		Sep. 30, 2013 Natural Gas Purchases [Member] Enable Midstream Partners [Member] OG&E [Member]		Sep. 30, 2014 Natural Gas Purchases [Member] Enable Midstream Partners [Member] OG&E [Member]		Sep. 30, 2013 Natural Gas Purchases [Member] Enable Midstream Partners [Member] OG&E [Member]		Sep. 30, 2014 Employment Costs [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Employment Costs [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2014 Employment Costs [Member] Enable Midstream Partners [Member] OG&E [Member]	Sep. 30, 2013 Employment Costs [Member] Enable Midstream Partners [Member] OG&E [Member]
Related Party Transaction [Line Items]
Operating expenses							$ 3.3	$ 6.6	$ 13.1	$ 10.9																	$ 25.0	$ 24.0	$ 78.0	$ 40.8
Electricity to power electric compression assets			4.1	3.9	10.1	5.2
Related Party Transaction, Purchases from Related Party											8.8	8.7	26.2	14.5	0.1	3.1	4.5	5.4	3.4	[1]	9.4	[1]	6.9	[1]	11.9	[1]
Accounts receivable - unconsolidated affiliates	$ 6.9	$ 12.4

[1] OG&E entered into a new contract with Enable to provide transportation services effective May 1, 2014 which also eliminated the natural gas storage services. In accordance with the cash-out provision of the contract, OG&E purchases gas from Enable when Enable's deliveries exceed OG&E's pipeline receipts. Enable purchases gas from OG&E when OG&E's pipeline receipts exceed Enable's deliveries.