Long-Term Debt - Convertible Debt (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 2024 USD ($) d $ / shares	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Long-term debt
Unamortized debt issuance costs		$ 103,200,000	$ 80,200,000
Net carrying amount		18,907,100,000	16,631,100,000
WEC Energy Group
Long-term debt
Senior notes		6,045,000,000	5,320,000,000
Interest expense		333,600,000	$ 260,800,000	$ 109,600,000
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2027
Long-term debt
Issuance of debt	$ 862,500,000
Interest rate	4.375%
Principal amount conversion rate applied to	$ 1,000
Initial conversion ratio	10.1243
Initial conversion price. per share | $ / shares	$ 98.77
Senior notes		862,500,000
Unamortized debt issuance costs		(8,000,000.0)
Net carrying amount		854,500,000
Fair value amount		920,600,000
Contractual interest expense		22,300,000
Amortization of debt issuance costs		1,900,000
Interest expense		24,200,000
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2027 | Early Redemption Terms
Long-term debt
Debt instrument, redemption price, percentage	100.00%
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2027 | Debt Conversion Terms One
Long-term debt
Threshold percentage of trigger	130.00%
Trading days | d	20
Consecutive trading days | d	30
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2027 | Debt Conversion Terms Two
Long-term debt
Threshold percentage of trigger	98.00%
Trading days | d	5
Consecutive trading days | d	10
Principal amount conversion rate applied to	$ 1,000
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2027 | Debt Conversion Terms Four
Long-term debt
Trading days prior to maturity | d	2
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2029
Long-term debt
Issuance of debt	$ 862,500,000
Interest rate	4.375%
Principal amount conversion rate applied to	$ 1,000
Initial conversion ratio	10.1243
Initial conversion price. per share | $ / shares	$ 98.77
Senior notes		862,500,000
Unamortized debt issuance costs		(8,800,000)
Net carrying amount		853,700,000
Fair value amount		929,100,000
Contractual interest expense		22,300,000
Amortization of debt issuance costs		1,200,000
Interest expense		$ 23,500,000
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2029 | Early Redemption Terms
Long-term debt
Trading days prior to early redemption | d	41
Threshold percentage of trigger	130.00%
Trading days | d	20
Consecutive trading days | d	30
Debt instrument, redemption price, percentage	100.00%
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2029 | Debt Conversion Terms One
Long-term debt
Threshold percentage of trigger	130.00%
Trading days | d	20
Consecutive trading days | d	30
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2029 | Debt Conversion Terms Two
Long-term debt
Threshold percentage of trigger	98.00%
Trading days | d	5
Consecutive trading days | d	10
Principal amount conversion rate applied to	$ 1,000
WEC Energy Group | WEC 4.375% Convertible Notes due June 1, 2029 | Debt Conversion Terms Three
Long-term debt
Trading days prior to redemption | d	2