Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		$ 9,600,000	$ 98,000,000
Defined Benefit Plan, Amount Billed to Service Company		$ 900,000	1,700,000	$ 1,700,000
Defined contribution plan, maximum annual contributions per employee (percent)		85.00%
Employer contributions to defined contribution plan		$ 3,500,000	3,300,000	3,300,000
Accumulated benefit obligation for our defined benefit pension plans		290,000,000	301,300,000
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax		(1,300,000)	2,100,000	6,400,000
THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amount Billed to Service Company		$ 900,000	1,700,000	1,700,000
Defined contribution plan, maximum annual contributions per employee (percent)		85.00%
Employer contributions to defined contribution plan		$ 3,500,000	3,300,000	3,300,000
Accumulated benefit obligation for our defined benefit pension plans		290,000,000	301,300,000
Defined Benefit Plan, Funded (Unfunded) Status of Plan		(7,200,000)
Defined Benefit Plan, Amount Billed to AES Ohio Generation		200,000	900,000	1,900,000
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax		$ (1,200,000)	2,200,000	6,400,000
Defined Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan employee vested percentage		100.00%
Defined benefit plan, percent forfeited if terminated, other than by death or disability, prior to full vesting (percent)		100.00%
Defined Benefit Plan [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan employee vested percentage		100.00%
Defined benefit plan, percent forfeited if terminated, other than by death or disability, prior to full vesting (percent)		100.00%
Management Employees [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan employee vested percentage		100.00%
Defined benefit plan, percent forfeited if terminated, other than by death or disability, prior to full vesting (percent)		100.00%
Cash Balance Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan employee vested percentage		100.00%
Defined benefit plan, percent forfeited if terminated, other than by death or disability, prior to full vesting (percent)		100.00%
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		$ 9,600,000	(98,000,000.0)
Payment for Pension Benefits		$ 7,500,000	$ 7,500,000	$ 9,800,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets		5.40%	4.60%	4.55%
Discount rate for obligations		5.14%	5.41%	2.83%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate		5.41%	2.83%	2.44%
Defined Benefit Plan, Plan Assets, Amount		$ 268,400,000	$ 274,400,000	$ 363,500,000
Service cost		3,000,000.0	4,900,000	4,500,000
Interest cost		15,800,000	9,600,000	8,200,000
Defined Benefit Plan, Funded (Unfunded) Status of Plan		$ (30,200,000)	(34,600,000)
Defined benefit plan, amortization period for underfunding excess		7 years
Pension [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		$ 9,600,000	(98,000,000.0)
Payment for Pension Benefits		$ 7,500,000	$ 7,500,000	$ 9,800,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets		5.40%	4.60%	4.55%
Discount rate for obligations		5.14%	5.41%	2.83%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate		5.41%	2.83%	2.44%
Defined Benefit Plan, Plan Assets, Amount		$ 268,400,000	$ 274,400,000	$ 363,500,000
Service cost		3,000,000.0	4,900,000	4,500,000
Interest cost		15,800,000	9,600,000	$ 8,200,000
Defined Benefit Plan, Funded (Unfunded) Status of Plan		$ (30,200,000)	(34,600,000)
Defined benefit plan, amortization period for underfunding excess		7 years
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded (Unfunded) Status of Plan			7,000,000
Postretirement [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded (Unfunded) Status of Plan		$ 7,200,000	$ 7,000,000
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated contribution to the defined benefit plans next year		$ 200,000
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		32.00%
Equity Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		32.00%
Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.15%
Decrease in pension cost due to change in return on assets	$ (2,900,000)
Decrease in pension cost due to change in discount rate	$ (300,000)
Forecast [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.15%
Decrease in pension cost due to change in return on assets	$ (2,900,000)
Decrease in pension cost due to change in discount rate	(300,000)
Forecast [Member] | Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits	7,500,000
Service cost	5,100,000
Defined Benefit Plan, Plan Assets, Administration Expense	1,600,000
Forecast [Member] | Pension [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits	7,500,000
Service cost	5,100,000
Defined Benefit Plan, Plan Assets, Administration Expense	$ 1,600,000
Forecast [Member] | SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Allocation Percentage	100.00%
Forecast [Member] | SERP [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Allocation Percentage	100.00%
Estimated contribution to the defined benefit plans next year	$ 200,000
Increase in Expected Rate of Return [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in Expected rate of return on plan assets	1.00%
Increase in Expected Rate of Return [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in Expected rate of return on plan assets	1.00%
Expected Increase in Discount Rate [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in discount rate for plan assets	0.25%
Expected Increase in Discount Rate [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in discount rate for plan assets	0.25%
Non-union Participant [Member] | First 1% of Eligible Compensation [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution (percent)		100.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay (percent)		1.00%
Non-union Participant [Member] | First 1% of Eligible Compensation [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution (percent)		100.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay (percent)		1.00%
Non-union Participant [Member] | Next 5% of Eligible Compensation [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution (percent)		50.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay (percent)		5.00%
Non-union Participant [Member] | Next 5% of Eligible Compensation [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution (percent)		50.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay (percent)		5.00%
Union Participant [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay (percent)		150.00%
Defined contribution plan, employer matching contribution cap		$ 2,750
Union Participant [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay (percent)		150.00%
Defined contribution plan, employer matching contribution cap		$ 2,750
Minimum [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		30.00%
Minimum [Member] | Equity Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		30.00%
Minimum [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		60.00%
Minimum [Member] | Fixed Income Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		60.00%
Maximum [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		40.00%
Maximum [Member] | Equity Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		40.00%
Maximum [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		70.00%
Maximum [Member] | Fixed Income Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		70.00%