Revenue - Narrative (Details) $ in Thousands	Nov. 22, 2023 USD ($) mi² term	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)
Disaggregation of Revenue [Line Items]
Prepayments received		$ 107,060	$ 80,265	$ 60,759	$ 61,367	$ 53,945	$ 54,678
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Disaggregation of Revenue [Line Items]
Remaining performance obligation, amount		$ 188,500
Remaining performance obligation, expected timing of satisfaction, period		30 years
Tampa Electric Company | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Disaggregation of Revenue [Line Items]
Agreement term	20 years
Number of agreement extension terms | term	2
Agreement extension term	10 years
Service area | mi²	2,000
Total scheduled prepayments	$ 34,500
Prepayments received		$ 6,900