Related-Party Transactions Related-Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Dividends, Common Stock		$ 185.0	$ 105.0
Operating Costs Charged [Member] \| OG&E [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party	$ 149.8	140.9	134.4
OG&E [Member] \| Enable Midstream Partners [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	15.9	16.3	14.0
OG&E [Member] \| Natural Gas Transportation [Member] \| Enable Midstream Partners [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	41.2	37.9	35.0
OG&E [Member] \| Natural Gas Purchases [Member] \| Enable Midstream Partners [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	(6.0)	(3.2)	(2.1)
Retained Earnings [Member]
Related Party Transaction [Line Items]
Dividends, Common Stock	$ 0.0	$ 185.0	$ 105.0

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 405
-Section 45
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 220
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