XML 81 R65.htm IDEA: XBRL DOCUMENT v3.24.0.1
Benefit Plans (Fair Value Measurements for Pension Plan Assets) (Details) - Pension [Member] - USD ($)
$ in Millions
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets $ 268.4 $ 274.4 $ 363.5
Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 1.8 1.9  
Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 266.6 272.5  
Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 0.0 0.0  
Defined Benefit Plan, Common Collective Trust      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 266.6 272.5  
Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 0.0 0.0  
Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 266.6 272.5  
Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 0.0 0.0  
THE DAYTON POWER AND LIGHT COMPANY [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 268.4 274.4 $ 363.5
THE DAYTON POWER AND LIGHT COMPANY [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 1.8 1.9  
THE DAYTON POWER AND LIGHT COMPANY [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 266.6 272.5  
THE DAYTON POWER AND LIGHT COMPANY [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 0.0 0.0  
THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 266.6 272.5  
THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 0.0 0.0  
THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 266.6 272.5  
THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Pension Plan Assets 0.0 0.0  
Debt Securities [Member] | Defined Benefit Plan, Common Collective Trust      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 121.1 125.7  
Debt Securities [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
Debt Securities [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 121.1 125.7  
Debt Securities [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
Debt Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 121.1 125.7  
Debt Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
Debt Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 121.1 125.7  
Debt Securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
U.S. Equities [Member] | Defined Benefit Plan, Common Collective Trust      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 84.5 88.5  
U.S. Equities [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
U.S. Equities [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 84.5 88.5  
U.S. Equities [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
U.S. Equities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 84.5 88.5  
U.S. Equities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
U.S. Equities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 84.5 88.5  
U.S. Equities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 1.8 1.9  
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 1.8 1.9  
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
Cash and Cash Equivalents [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 1.8 1.9  
Cash and Cash Equivalents [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 1.8 1.9  
Cash and Cash Equivalents [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
Cash and Cash Equivalents [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
US Government Debt Securities | Defined Benefit Plan, Common Collective Trust      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 61.0 58.3  
US Government Debt Securities | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
US Government Debt Securities | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 61.0 58.3  
US Government Debt Securities | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
US Government Debt Securities | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 61.0 58.3  
US Government Debt Securities | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 0.0 0.0  
US Government Debt Securities | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities 61.0 58.3  
US Government Debt Securities | THE DAYTON POWER AND LIGHT COMPANY [Member] | Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Total Equity Securities $ 0.0 $ 0.0