Goodwill (Table) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 1,690.7	$ 1,690.7
Gas Distribution Operations
Goodwill [Line Items]
Goodwill	1,690.7
Electric Operations
Goodwill [Line Items]
Goodwill	0.0
Corporate and Other
Goodwill [Line Items]
Goodwill	$ 0.0