Description of Business and Accounting Policies - Narrative (Details)		1 Months Ended	3 Months Ended			8 Months Ended	12 Months Ended
	Sep. 08, 2021	Sep. 30, 2021	Dec. 31, 2024 USD ($) Employee	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 06, 2021 USD ($)	Dec. 31, 2024 USD ($) Employee	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Aug. 31, 2023 USD ($)	Mar. 31, 2023 Facility
Description of Business and Accounting Policies [Line Items]
Entity number of employees | Employee			2,200				2,200
Company employees participating in collective bargaining agreement, percentage			44.00%				44.00%
Trade receivables due from customers, range, minimum							21 days
Trade receivables due from customers, range, maximum							90 days
Unbilled receivables, current			$ 2,700,000				$ 2,700,000	$ 2,800,000
Allowance for uncollectible accounts			15,000,000				15,000,000	14,800,000
Goodwill, impairment loss							0	0	$ 0
Impairment losses on Indefinite-lived intangible assets							0	0	0
Loss on impairment of long-lived assets					$ 2,700,000		3,100,000	0	2,700,000
Cost method investments			10,100,000				10,100,000	10,000,000
Impairment losses on cost method investments							$ 0	0	0
Service delivery period, indefeasible right of use contracts, upper range, in years							25 years
Advertising expense							$ 21,700,000	25,000,000.0	23,500,000
Regulatory taxes included in revenue							30,500,000	34,000,000	32,900,000
Regulatory taxes included in expense							34,800,000	38,000,000	36,900,000
Capital contributions committed by parent										$ 600,000,000
Capital contributions received from parent							200,000,000	400,000,000
Number of receivable facility | Facility											2
Cash-settled awards, vesting period	6 months	4 years
Cash-settled awards, remaining vesting percentage	20.00%
Cash-settled awards, vesting expiration period	8 years
Remaining cash settled awards vesting period	18 months
Expense incurred for cash-payment awards								300,000	3,300,000
Officers and Key Employees [Member]
Description of Business and Accounting Policies [Line Items]
Compensation expense							0	0	$ 0
Cash-settled awards, granted value						$ 10,500,000
Additional Paid-in Capital [Member]
Description of Business and Accounting Policies [Line Items]
Capital contributions received from parent			$ 200,000,000	$ 400,000,000			$ 200,000,000	$ 400,000,000