Property, Plant, and Equipment - Balances (Details) $ in Millions	Dec. 31, 2023 USD ($)	Sep. 30, 2023 MW	Jun. 30, 2023 MW	Dec. 31, 2022 USD ($)
Property, plant, and equipment
Accumulated depreciation	$ 11,073.1			$ 10,383.8
Net property, plant, and equipment	31,581.5			29,113.8
WE | West Riverside Energy Center
Property, plant, and equipment
Capacity of generation unit | MW		100	100
OCPP Units 5-8 | WE
Property, plant, and equipment
Net book value of plant to be retired	783.7
Columbia Energy Center Units 1 and 2 | WPS
Property, plant, and equipment
Net book value of plant to be retired	259.8
Regulated operations
Property, plant, and equipment
Accumulated depreciation	8,907.9			8,416.2
Net	24,215.3			22,889.2
CWIP	1,118.3			972.1
Net property, plant, and equipment	25,333.6			23,861.3
Regulated operations | Electric - generation
Property, plant, and equipment
Property, plant, and equipment	6,190.4			5,480.5
Regulated operations | Electric - distribution
Property, plant, and equipment
Property, plant, and equipment	8,688.0			8,233.3
Regulated operations | Natural gas - distribution, storage, and transmission
Property, plant, and equipment
Property, plant, and equipment	14,851.3			14,203.3
Regulated operations | Property, plant, and equipment to be retired, net
Property, plant, and equipment
Property, plant, and equipment to be retired, net	1,043.5			1,085.6
Regulated operations | Other
Property, plant, and equipment
Property, plant, and equipment	2,350.0			2,302.7
Non-regulated operations
Property, plant, and equipment
Accumulated depreciation	1,227.5			1,082.3
Net	6,211.8			5,170.9
CWIP	36.1			81.6
Net property, plant, and equipment	6,247.9			5,252.5
Non-regulated operations | Other
Property, plant, and equipment
Property, plant, and equipment	14.3			23.8
Non-regulated operations | We Power generation
Property, plant, and equipment
Property, plant, and equipment	3,295.9			3,237.1
Non-regulated operations | Renewable generation
Property, plant, and equipment
Property, plant, and equipment	3,667.7			2,537.1
Non-regulated operations | Natural gas storage
Property, plant, and equipment
Property, plant, and equipment	291.6			292.2
Non-regulated operations | Corporate services
Property, plant, and equipment
Property, plant, and equipment	169.8			163.0
Non-Utility Energy Infrastructure | Non-regulated operations
Property, plant, and equipment
Property, plant, and equipment	$ 7,255.2			$ 6,066.4