CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
CURRENT ASSETS
Cash and cash equivalents	$ 0.0	$ 1.1	$ 67.5	$ 0.0
Accounts Receivable, after Allowance for Credit Loss, Current	173.2	157.8
Accrued unbilled revenues	94.7	67.6
Fuel inventories	(46.1)	(36.5)
Income taxes receivable	4.1	8.1
Materials and supplies, at average cost	119.0	116.2
Fuel clause under recoveries	0.4	0.0
Other	47.1	41.2
Total current assets	484.6	428.5
OTHER PROPERTY AND INVESTMENTS
Investment in unconsolidated affiliates	451.7	397.4	376.5
Other	90.3	86.7
Total other property and investments	542.0	484.1
PROPERTY, PLANT AND EQUIPMENT
In service	13,582.7	13,296.7
Construction work in progress	181.0	145.5
Total property, plant and equipment	13,763.7	13,442.2
Less: accumulated depreciation	4,188.5	4,067.6
Property, Plant and Equipment, Net	9,575.2	9,374.6
DEFERRED CHARGES AND OTHER ASSETS
Regulatory assets	1,278.3	415.6
Other	19.4	16.0
Total deferred charges and other assets	1,297.7	431.6
TOTAL ASSETS	11,899.5	10,718.8	10,439.1
CURRENT LIABILITIES
Short-term Debt	384.5	95.0
Accounts payable	189.8	251.5
Dividends payable	80.6	80.5
Customer deposits	80.9	81.1
Accrued taxes	56.5	55.7
Accrued interest	40.8	40.2
Accrued compensation	36.0	31.1
Fuel clause over recoveries	4.7	28.6
Other	37.5	33.7
Total current liabilities	911.3	697.4
LONG-TERM DEBT	4,495.2	3,494.4
DEFERRED CREDITS AND OTHER LIABILITIES
Accrued benefit obligations	179.8	231.4
Deferred income taxes	1,206.5	1,268.6
Deferred investment tax credits	10.9	10.9
Regulatory liabilities	1,259.7	1,188.9
Other	195.3	195.4
Total deferred credits and other liabilities	2,852.2	2,895.2
Total liabilities	8,258.7	7,087.0
COMMITMENTS AND CONTINGENCIES (NOTE 14)
STOCKHOLDERS' EQUITY
Common stockholders' equity	1,120.9	1,124.6
Retained earnings	2,547.9	2,544.6
Accumulated other comprehensive loss, net of tax	(27.9)	(32.1)	(27.9)	(27.9)
Total stockholders' equity	3,640.8	3,631.8
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	11,899.5	10,718.8
Treasury Stock, Carrying Basis	(0.1)	(5.3)
Accounts Receivable, Allowance for Credit Loss	1.8	2.6
OG&E [Member]
CURRENT ASSETS
Cash and cash equivalents	0.0	0.0	67.5	0.0
Accounts Receivable, after Allowance for Credit Loss, Current	173.2	156.3
Accrued unbilled revenues	94.7	67.7
Advances to parent	118.0	272.0
Fuel inventories	(46.1)	(36.5)
Materials and supplies, at average cost	119.0	116.2
Fuel clause under recoveries	0.4	0.0
Other	38.3	36.9
Total current assets	589.7	685.6
OTHER PROPERTY AND INVESTMENTS
Total other property and investments	3.9	4.1
PROPERTY, PLANT AND EQUIPMENT
In service	13,576.6	13,290.6
Construction work in progress	181.0	145.5
Total property, plant and equipment	13,757.6	13,436.1
Less: accumulated depreciation	4,188.5	4,067.6
Property, Plant and Equipment, Net	9,569.1	9,368.5
DEFERRED CHARGES AND OTHER ASSETS
Regulatory assets	1,278.3	415.6
Other	18.3	15.2
Total deferred charges and other assets	1,296.6	430.8
TOTAL ASSETS	11,459.3	10,489.0
CURRENT LIABILITIES
Accounts payable	178.9	236.7
Customer deposits	80.9	81.1
Accrued taxes	53.4	53.3
Accrued interest	40.5	40.2
Accrued compensation	26.6	22.5
Fuel clause over recoveries	4.7	28.6
Other	37.4	33.5
Total current liabilities	422.4	495.9
LONG-TERM DEBT	3,995.4	3,494.4
DEFERRED CREDITS AND OTHER LIABILITIES
Accrued benefit obligations	98.0	135.4
Deferred income taxes	951.2	1,020.8
Deferred investment tax credits	10.9	10.9
Regulatory liabilities	1,259.7	1,188.9
Other	163.7	167.1
Total deferred credits and other liabilities	2,483.5	2,523.1
Total liabilities	6,901.3	6,513.4
STOCKHOLDERS' EQUITY
Common stockholders' equity	1,570.6	1,039.5
Retained earnings	2,987.4	2,936.1
Total stockholders' equity	4,558.0	3,975.6	$ 3,983.7	$ 3,958.3
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 11,459.3	$ 10,489.0