Investments in Affiliates and Other Entities (Details) mile in Thousands, $ in Millions	1 Months Ended	3 Months Ended			9 Months Ended	12 Months Ended
	Mar. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2020 mile	Dec. 01, 2022 USD ($)	Dec. 31, 2021 USD ($)	Oct. 31, 2021
Summary Of Significant Accounting Policies [Line Items]
Equity method investments		$ 135.4			$ 135.4			$ 101.2
Length of electric transmission and distribution system | mile						18
Investment balance		27.8			27.8			130.2
Investment in real estate		26.3		$ 23.5	26.3
LUMA Energy, LLC
Summary Of Significant Accounting Policies [Line Items]
Term of operation and maintenance agreement						15 years
LUMA Energy, LLC | Forecast
Summary Of Significant Accounting Policies [Line Items]
Fee due in the event of expiration of service agreement							$ 115.0
Integral Affiliates
Summary Of Significant Accounting Policies [Line Items]
Equity method investments		82.2			82.2			67.8
Due from related parties		83.0			83.0			49.0
Due to related parties		23.2			23.2			56.3
Revenue from related parties		38.2			89.7
Related party cost of sales		38.8			111.1
LUMA Energy, LLC
Summary Of Significant Accounting Policies [Line Items]
Equity method investments		$ 40.3			$ 40.3			30.6
Equity interest		50.00%			50.00%
Integral Affiliate Offering Right-of-way Solutions
Summary Of Significant Accounting Policies [Line Items]
Equity method investments		$ 27.0			$ 27.0			28.5
Equity interest									44.00%
Non-Integral Unconsolidated Affiliates
Summary Of Significant Accounting Policies [Line Items]
Equity method investments		53.2			53.2			$ 33.4
Broadband Technology Provider
Summary Of Significant Accounting Policies [Line Items]
Preferred non-controlling interest				$ 90.0
Starry Group Holdings, Inc.
Summary Of Significant Accounting Policies [Line Items]
Equity security fair value		15.0			15.0
Payments to acquire equity securities	$ 1.5
Decrease in fair value		$ (26.5)			$ (76.5)
Technology Incubation Company
Summary Of Significant Accounting Policies [Line Items]
Cost method investments, gain on sale			$ 6.7
Cost method investments, gain on sale, after tax			$ 5.0