Employee Benefits - Target Asset Allocations (Details)	Dec. 31, 2024
Pension Plan | Wisconsin Energy Corporation | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	25.00%
Pension Plan | Wisconsin Energy Corporation | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	55.00%
Pension Plan | Wisconsin Energy Corporation | Private equity and real estate
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	20.00%
Pension Plan | Integrys | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	25.00%
Pension Plan | Integrys | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	55.00%
Pension Plan | Integrys | Private equity and real estate
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	20.00%
OPEB Plan | Wisconsin Energy Corporation | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	45.00%
OPEB Plan | Wisconsin Energy Corporation | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	45.00%
OPEB Plan | Wisconsin Energy Corporation | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	10.00%
OPEB Plan | Integrys | Largest trust 1 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	45.00%
OPEB Plan | Integrys | Largest trust 1 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	45.00%
OPEB Plan | Integrys | Largest trust 1 | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	10.00%
OPEB Plan | Integrys | Largest trust 2 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	45.00%
OPEB Plan | Integrys | Largest trust 2 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	45.00%
OPEB Plan | Integrys | Largest trust 2 | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (as a percent)	10.00%