Schedule I - Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 37.5	$ 49.8	$ 61.9	$ 26.0
Other	97.5	58.8
Current assets	2,168.7	2,206.8
Long-term assets
Other	461.0	489.7
Long-term assets	27,954.5	27,148.4
Total assets	30,123.2	29,355.2	14,905.0
Current liabilities
Short-term debt	860.2	1,095.0
Other	388.9	471.2
Current liabilities	2,431.6	2,709.0
Long-term liabilities
Long-term debt	9,158.2	9,124.1
Other	1,164.4	1,071.7
Long-term liabilities	18,731.4	17,961.0
Equity
Common shareholders' equity	8,960.2	8,685.2	4,450.1	4,263.4
Total liabilities and equity	30,123.2	29,355.2
WEC Energy Group
Current assets
Cash and cash equivalents	1.2	1.3	$ 37.3	$ 0.3
Accounts receivable from related parties	1.8	13.2
Notes receivable from related parties	76.4	123.2
Prepaid taxes	47.6	0.0
Other	0.5	2.2
Current assets	127.5	139.9
Long-term assets
Investments in subsidiaries	11,155.4	10,792.6
Other	134.7	254.0
Long-term assets	11,290.1	11,046.6
Total assets	11,417.6	11,186.5
Current liabilities
Short-term debt	321.8	307.9
Accounts payable to related parties	3.2	1.7
Notes payable to related parties	241.3	119.0
Accrued taxes	0.0	75.6
Other	10.3	17.5
Current liabilities	576.6	521.7
Long-term liabilities
Long-term debt	1,890.0	1,887.2
Other	21.2	122.8
Long-term liabilities	1,911.2	2,010.0
Equity
Common shareholders' equity	8,929.8	8,654.8
Total liabilities and equity	$ 11,417.6	$ 11,186.5