Dispositions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Total Income on Discontinued Operations as Presented on the Statements of Income	$ 0.0	$ 10.5
Corporate and Other [Member]
Other Revenues		127.7
Other Operation Expense		85.0
Maintenance Expense		8.3
Depreciation and Amortization Expense		9.1
Taxes Other Than Income Taxes		4.0
Total Expense		106.4
Other Expense		(4.4)
Pretax Income of Discontinued Operations		16.9
Income Tax Expense		6.3
Equity Earnings of Unconsolidated Subsidiaries		(0.1)
Total Income on Discontinued Operations as Presented on the Statements of Income		$ 10.5