Pension and Postretirement Plans - Narrative (Details) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2025 USD ($)	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) Plan	Sep. 30, 2024 USD ($)
Cincinnati Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Number of noncontributory defined benefit pension plans \| Plan					3
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Pension curtailment gain					$ 0.0	$ 0.0
Pension settlement gain	$ 2.0			$ 2.8	3.8	3.2
Pension Plans, Defined Benefit [Member] \| Hawaii Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement	4.6	$ 6.5	$ 8.0
Decrease in benefit obligations	4.6	6.5	8.0
Pension settlement gain	0.5	0.6	1.0
Pension Plans, Defined Benefit [Member] \| Cincinnati Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement		10.6	0.7
Decrease in benefit obligations		10.6	0.7
Pension settlement gain	1.5	$ 0.2
Pension Plans, Defined Benefit [Member] \| Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Contributions to pension plans					1.7	0.6
Expected future employer contributions, next fiscal year	2.0				2.0
Pension Plans, Defined Benefit [Member] \| Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Contributions to pension plans					1.8	1.4
Expected future employer contributions, next fiscal year	2.0				2.0
Pension Plans, Defined Benefit [Member] \| Management Employees [Member] \| Cincinnati Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement	1.4
Decrease in benefit obligations	1.4
Pension Plans, Defined Benefit [Member] \| Union Employees [Member] \| Cincinnati Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement	3.9
Decrease in benefit obligations	3.9
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Expected future employer contributions, next fiscal year	7.0				7.0
Contributions to postretirement plans					4.7	5.0
Pension curtailment gain			$ 0.2		0.2	0.0
Pension settlement gain	$ 0.0			$ 0.0	$ 0.0	$ 0.0

CINCINNATI BELL INC 10-Q