Regulated Operations (Details) - USD ($) $ in Millions		Jun. 30, 2022	Dec. 31, 2021
Schedule of Regulatory Assets and Liabilities [Line Items]
Fuel clause under recoveries		$ 271.7	$ 151.9
Current Regulatory Assets		1,041.0	182.6
Non-Current Regulatory Assets		505.1	1,230.8
Current Regulatory Liabilities		4.6	2.5
Non-Current Regulatory Liabilities		1,205.3	1,231.1
Other (B)
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Liabilities	[1]	4.6	2.5
Non-Current Regulatory Liabilities		3.1	3.6
Income taxes recoverable from customers, net
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Liabilities		918.5	930.7
Accrued removal obligations, net
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Liabilities		283.7	296.8
Winter Storm Uri costs | OKLAHOMA
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Assets		750.5	0.0
Non-Current Regulatory Assets		0.0	747.9
Winter Storm Uri costs | ARKANSAS
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		83.9	88.9
Benefit obligations regulatory asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		101.0	109.2
Oklahoma deferred storm expenses
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		210.5	172.8
Smart Grid
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		0.4	3.9
Dry Scrubber Regulatory Asset [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		18.5	18.9
Unamortized loss on reacquired debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		8.5	8.9
Deferred Pension Expenses [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		12.1	12.1
Other Regulatory Asset [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Assets	[2]	10.7	9.7
Non-Current Regulatory Assets		10.2	10.4
Pension tracker
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		45.7	42.9
SPP Cost Tracker Rider Under Recovery
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Assets	[2]	8.1	9.3
COVID-19 Deferred Expenses
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		8.3	8.2
Oklahoma Energy Efficiency Rider Under Recovery
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Assets	[2]	0.0	11.7
Deferred Plant Expense
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		$ 6.0	$ 6.7

[1] Included in Other Current Liabilities in the condensed balance sheets.

[2] Included in Other Current Assets in the condensed balance sheets. The Oklahoma Winter Storm Uri regulatory asset was reclassified as current at June 30, 2022, in anticipation of the securitization process being completed in July 2022 and OG&E receiving funds from the ODFA.