Assets and Liabilities Held-For-Sale and Dispositions (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 15, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		$ (119.9)	$ (793.3)	$ (231.4)
Fixed-asset impairment (Note 15)	$ 623.5	175.8	859.0	0.0
Proceeds from sale of business		70.1	75.5	1.3
Miami Fort and Zimmer [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		25.7	(13.5)	5.6
Fixed-asset impairment (Note 15)			294.1
Proceeds from sale of business		50.0
Proceeds from Purchase Price Adjustment		20.1
Gain (Loss) on Disposition of Business		14.0
AES Ohio Generation peakers [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		16.9	20.0	23.9
Accounts receivable, net		3.8
Fixed-asset impairment (Note 15)		109.4	$ 1.3	$ 0.0
Inventory, Net		7.6
Disposal Group, Including Discontinued Operations, Taxes Applicable to Subsequent Years		4.9
Property, plant & equipment, net		233.7
Other assets		0.3
Total assets of the disposal group classified as held for sale in the balance sheets		250.3
Accounts payable		3.9
Disposal Group, Including Discontinued Operation, Accrued Income Tax Payable		3.6
Disposal Group, Including Discontinued Operation, Taxes Payable		4.9
Asset Retirement Obligation, Held for Sale		0.6
Other liabilities		0.2
Total liabilities of the disposal group classified as held for sale in the balance sheets		$ 13.2
Asset Purchase Agreement Sale Price, Cash					$ 241.0