EMPLOYEE BENEFITS - AMOUNTS NOT YET RECOGNIZED IN NET PERIODIC BENEFIT COST (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits
Net regulatory assets (liabilities)
Net actuarial loss (gain)	$ 87.3	$ 179.9
Prior service credits	0.0	0.0
Total	87.3	179.9
OPEB Benefits
Net regulatory assets (liabilities)
Net actuarial loss (gain)	(64.6)	(67.7)
Prior service credits	(41.4)	(54.6)
Total	$ (106.0)	$ (122.3)

The net amount of prior service cost or credit relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost, and that are recognized as net regulatory assets.

No definition available.

Name:	wps_DefinedBenefitPlanNetRegulatoryAssetsPriorServiceCostCredit
Namespace Prefix:	wps_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant