Short-Term Debt and Lines of Credit - Outstanding Amounts (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Commercial paper	$ 1,440.1	$ 1,444.6
WE
Short-term Debt [Line Items]
Maximum debt to capitalization ratio	65.00%
WPS
Short-term Debt [Line Items]
Maximum debt to capitalization ratio	65.00%
WG
Short-term Debt [Line Items]
Maximum debt to capitalization ratio	65.00%
PGL
Short-term Debt [Line Items]
Maximum debt to capitalization ratio	65.00%
WEC Energy Group
Short-term Debt [Line Items]
Commercial paper	$ 548.4	494.8
Maximum debt to capitalization ratio	70.00%
Commercial paper
Short-term Debt [Line Items]
Commercial paper	$ 1,440.1	$ 1,444.6
Average interest rate on amount outstanding	2.92%	1.77%
Average amount outstanding during the year	$ 1,350.7
Weighted Average interest rate during the year	2.32%

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13)(2))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 210
-Section S99
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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