Long-Term Debt Schedule of current maturities of long-term debt (Details) $ in Millions	Dec. 31, 2019 USD ($)
Current maturities of long-term debt [Line Items]
Total	$ 686.9
WEC Energy Group
Current maturities of long-term debt [Line Items]
Total	$ 400.0
WEC Energy Group Senior Notes (unsecured) \| WEC Energy Group
Current maturities of long-term debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.45%
Senior Notes, Current	$ 400.0
Integrys Senior Notes (unsecured) \| Integrys Holding Inc
Current maturities of long-term debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.17%
Senior Notes, Current	$ 250.0
Bluewater Gas Storage Senior Notes (unsecured) \| Bluewater Gas Storage, LLC
Current maturities of long-term debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.76%
Senior Notes, Current	$ 2.5
4.91% We Power Subsidiaries Notes - PWGS (secured, nonrecourse) \| We Power
Current maturities of long-term debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.91%
Secured Debt, Current	$ 6.6
5.209%We Power Subsidiaries Notes - ERGS (secured, nonrecourse) \| We Power
Current maturities of long-term debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.209%
Secured Debt, Current	$ 12.6
4.673% We Power Subsidiaries Notes - ERGS (secured, nonrecourse) \| We Power
Current maturities of long-term debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.673%
Secured Debt, Current	$ 9.7
6.00% We Power Subsidiaries Notes - PWGS (secured, nonrecourse) \| We Power
Current maturities of long-term debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Secured Debt, Current	$ 5.5

Contractual interest rate for funds borrowed, under the debt agreement.

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