Schedule 1 - Guarantees (Details) $ in Millions	Dec. 31, 2023 USD ($)
Notes to parent company financial statements
Total guarantees	$ 167.6
Guarantees expiring in less than one year	58.3
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	109.3
Standby letters of credit
Notes to parent company financial statements
Total guarantees	122.4
Guarantees expiring in less than one year	24.7
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	97.7
Surety bonds
Notes to parent company financial statements
Total guarantees	33.6
Guarantees expiring in less than one year	33.6
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	0.0
Other guarantees
Notes to parent company financial statements
Total guarantees	11.6
Guarantees expiring in less than one year	0.0
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	11.6
WEC Energy Group
Notes to parent company financial statements
Total guarantees	312.0
Guarantees expiring in less than one year	72.5
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	239.5
WEC Energy Group | WECI
Notes to parent company financial statements
Total guarantees	177.3
WEC Energy Group | Bluewater
Notes to parent company financial statements
Total guarantees	10.2
WEC Energy Group | UMERC
Notes to parent company financial statements
Total guarantees	4.2
WEC Energy Group | Guarantees supporting business operations
Notes to parent company financial statements
Total guarantees	191.7
Guarantees expiring in less than one year	14.4
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	177.3
WEC Energy Group | Standby letters of credit
Notes to parent company financial statements
Total guarantees	75.1
Guarantees expiring in less than one year	24.5
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	50.6
WEC Energy Group | Surety bonds
Notes to parent company financial statements
Total guarantees	33.6
Guarantees expiring in less than one year	33.6
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	0.0
WEC Energy Group | Other guarantees
Notes to parent company financial statements
Total guarantees	11.6
Guarantees expiring in less than one year	0.0
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	$ 11.6