Schedule 1 - Guarantees (Details) $ in Millions	Dec. 31, 2022 USD ($)
Notes to parent company financial statements
Total guarantees	$ 159.1
Guarantees expiring in less than one year	41.9
Guarantees expiring within one to three years	0.3
Guarantees with expiration over three years	116.9
Standby letters of credit (1)
Notes to parent company financial statements
Total guarantees	115.7
Guarantees expiring in less than one year	8.0
Guarantees expiring within one to three years	0.2
Guarantees with expiration over three years	107.5
Surety bonds (2)
Notes to parent company financial statements
Total guarantees	34.0
Guarantees expiring in less than one year	33.9
Guarantees expiring within one to three years	0.1
Guarantees with expiration over three years	0.0
Other guarantees (3)
Notes to parent company financial statements
Total guarantees	9.4
Guarantees expiring in less than one year	0.0
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	9.4
WEC Energy Group
Notes to parent company financial statements
Total guarantees	660.3
Guarantees expiring in less than one year	469.7
Guarantees expiring within one to three years	1.3
Guarantees with expiration over three years	189.3
WEC Energy Group | WECI
Notes to parent company financial statements
Total guarantees	532.0
WEC Energy Group | Bluewater
Notes to parent company financial statements
Total guarantees	11.3
WEC Energy Group | UMERC
Notes to parent company financial statements
Total guarantees	5.2
WEC Energy Group | Guarantees supporting business operations
Notes to parent company financial statements
Total guarantees	548.5
Guarantees expiring in less than one year	427.8
Guarantees expiring within one to three years	1.2
Guarantees with expiration over three years	119.5
WEC Energy Group | Standby letters of credit (1)
Notes to parent company financial statements
Total guarantees	68.4
Guarantees expiring in less than one year	8.0
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	60.4
WEC Energy Group | Surety bonds (2)
Notes to parent company financial statements
Total guarantees	34.0
Guarantees expiring in less than one year	33.9
Guarantees expiring within one to three years	0.1
Guarantees with expiration over three years	0.0
WEC Energy Group | Other guarantees (3)
Notes to parent company financial statements
Total guarantees	9.4
Guarantees expiring in less than one year	0.0
Guarantees expiring within one to three years	0.0
Guarantees with expiration over three years	$ 9.4