Investment in Unconsolidated Affiliates Summarized Income Statement of Equity Method Investment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Summarized Income Statement of Equity Method Investment [Abstract]
Operating revenues	$ 826.7	$ 502.0	$ 1,828.3	$ 502.0
Cost of sales	478.2	294.6	1,110.8	294.6
Operating income	138.6	75.0	300.5	75.0
Net income attributable to Enable	$ 120.2	$ 65.1	$ 269.4	$ 65.1