Schedule I - Short-Term Notes Receivable from Related Parties (Details) - WEC Energy Group - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Notes to parent company financial statements
Short-term notes receivable from related parties	$ 110.8	$ 22.5
Integrys
Notes to parent company financial statements
Short-term notes receivable from related parties	68.1	0.0
UMERC
Notes to parent company financial statements
Short-term notes receivable from related parties	30.7	9.0
Wispark
Notes to parent company financial statements
Short-term notes receivable from related parties	$ 12.0	$ 13.5

Amounts due from parties associated with the reporting entity as evidenced by a written promise to pay, due within 1 year (or 1 business cycle).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant