REGULATORY ENVIRONMENT - WI 2020 AND 2021 RATES - MARCH APPLICATION (Details) - Public Service Commission of Wisconsin (PSCW) - March 2019 Rate Application $ in Millions	1 Months Ended
Mar. 31, 2019 USD ($) utility solar_projects
WE \| 2020 and 2021 rates
Public Utilities, General Disclosures [Line Items]
Requested return on equity (as a percent)	10.35%
Requested common equity component average (as a percent)	52.00%
WE \| Electric rates \| 2020 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 83
Requested rate increase (as a percent)	2.90%
WE \| Electric rates \| 2020 rates \| Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures [Line Items]
Amortization of regulatory liabilities	$ 94
WE \| Electric rates \| 2021 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 83
Requested rate increase (as a percent)	2.90%
WE \| Electric rates \| 2021 rates \| Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures [Line Items]
Amortization of regulatory liabilities	$ 17
WE \| Natural gas rates \| 2020 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 15
Requested rate increase (as a percent)	3.90%
WE \| Steam rates \| 2020 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 1
Requested rate increase (as a percent)	4.50%
WG \| 2020 and 2021 rates
Public Utilities, General Disclosures [Line Items]
Requested return on equity (as a percent)	10.30%
Requested common equity component average (as a percent)	52.00%
WG \| Natural gas rates \| 2020 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 11
Requested rate increase (as a percent)	1.80%
WPS \| 2020 and 2021 rates
Public Utilities, General Disclosures [Line Items]
Requested return on equity (as a percent)	10.35%
Requested common equity component average (as a percent)	52.00%
WPS \| Electric rates \| 2020 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 49
Requested rate increase (as a percent)	4.90%
WPS \| Electric rates \| 2020 rates \| Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures [Line Items]
Amortization of regulatory liabilities	$ 16
WPS \| Electric rates \| 2020 rates \| Earnings sharing mechanisms
Public Utilities, General Disclosures [Line Items]
Amortization of regulatory liabilities	21
WPS \| Electric rates \| 2021 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 49
Requested rate increase (as a percent)	4.90%
WPS \| Electric rates \| 2021 rates \| Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures [Line Items]
Amortization of regulatory liabilities	$ 24
WPS \| Electric rates \| 2020 and 2021 rates
Public Utilities, General Disclosures [Line Items]
Number of solar projects \| solar_projects	2
WPS \| Natural gas rates \| 2020 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 7
Requested rate increase (as a percent)	2.40%
WPS \| Natural gas rates \| 2020 rates \| Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures [Line Items]
Amortization of regulatory liabilities	$ 7
WPS \| Natural gas rates \| 2021 rates
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 7
Requested rate increase (as a percent)	2.40%
WE, WG, and WPS \| 2020 and 2021 rates
Public Utilities, General Disclosures [Line Items]
Number of utilities with earnings sharing mechanism \| utility	3
Percentage of first 25 basis points of additional earnings retained by the utility	100.00%
Return on equity in excess of authorized amount (as a percent)	0.25%
Percentage of additional earnings between 25 and 75 basis points refunded to customers	50.00%
Return on equity in excess of first 25 basis points above authorized amount (as a percent)	0.50%
Percentage of earnings in excess of 75 basis points refunded to customers	100.00%

The increase (decrease) during the reporting period in regulated liabilities. Regulated liabilities are created when regulatory agency permits an entity to defer revenues to the balance sheet.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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The number of solar projects for which acquisition approval has been requested from a regulatory agency.

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