Investment in Unconsolidated Affiliates Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended				6 Months Ended				3 Months Ended		6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Operating Costs Charged [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Operating Costs Charged [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Operating Costs Charged [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Operating Costs Charged [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Natural Gas Transportation [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Natural Gas Transportation [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Natural Gas Transportation [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Natural Gas Transportation [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Natural Gas Storage [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Natural Gas Storage [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Natural Gas Storage [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Natural Gas Storage [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Natural Gas Purchases [Member] Enable Midstream Partners [Member] Og and E [Member]		Jun. 30, 2013 Natural Gas Purchases [Member] Enable Midstream Partners [Member] Og and E [Member]		Jun. 30, 2014 Natural Gas Purchases [Member] Enable Midstream Partners [Member] Og and E [Member]		Jun. 30, 2013 Natural Gas Purchases [Member] Enable Midstream Partners [Member] Og and E [Member]		Jun. 30, 2014 Employment Costs [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Employment Costs [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2014 Employment Costs [Member] Enable Midstream Partners [Member] Og and E [Member]	Jun. 30, 2013 Employment Costs [Member] Enable Midstream Partners [Member] Og and E [Member]
Related Party Transaction [Line Items]
Operating expenses							$ 3.8	$ 4.3	$ 9.8	$ 4.3																	$ 22.2	$ 16.8	$ 53.0	$ 16.8
Electricity to power electric compression assets			3.3	1.3	6.0	1.3
Related Party Transaction, Purchases from Related Party											8.7	5.8	17.4	5.8	1.1	2.3	4.4	2.3	(1.4)	[1]	2.5	[1]	3.5	[1]	2.5	[1]
Accounts receivable - unconsolidated affiliates	$ 7.4	$ 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.