Consolidated Statements of Capitalization - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Common equity	$ 8,960.2	$ 8,685.2
Preferred stock of subsidiary	30.4	30.4
Obligations under capital leases	29.6	59.9
Total	9,352.0	9,314.6
Integrys acquisition fair value adjustment	33.3	41.1
Unamortized debt issuance costs	(38.1)	(37.8)
Unamortized discount, net and other	31.8	36.1
Total long-term debt, including current portion	9,315.4	9,281.8
Current portion of long-term debt and capital lease obligations	(157.2)	(157.7)
Total long-term debt	9,158.2	9,124.1
Total long-term capitalization	$ 18,118.4	$ 17,809.3
WEC Senior Notes due June 15, 2018 [Member]
Debt Instrument, Interest Rate, Stated Percentage	1.65%
WEC Senior Notes due June 15, 2020 [Member]
Debt Instrument, Interest Rate, Stated Percentage	2.45%
WEC Senior Notes due June 15, 2025 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.55%
Notes (unsecured), 6.20% due 2033 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.20%
Junior Notes (unsecured), 6.25% due 2067 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Debentures (unsecured), 1.70% due 2018 [Member]
Debt Instrument, Interest Rate, Stated Percentage	1.70%
Debentures (unsecured), 4.25% due 2019 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.25%
Debentures (unsecured) 2.95% due 2021 [Member]
Debt Instrument, Interest Rate, Stated Percentage	2.95%
Wis Elec Debenture due June 1, 2025 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.10%
Debentures (unsecured), 6-1/2% due 2028 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Debentures (unsecured), 5.625% due 2033 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.625%
Debentures (unsecured), 5.70% due 2036 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.70%
Debentures (unsecured), 3.65% due 2042 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.65%
Debentures (unsecured), 4.25% due 2044 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.25%
Wis Elec Debenture due December 15, 2045 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.30%
Debentures (unsecured), 6-7/8% due 2095 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.875%
Long Term Debt 5.65 Percent Series, Due 2017 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.65%
Long Term Debt 1.65% Series, Due 2018 [Member]
Debt Instrument, Interest Rate, Stated Percentage	1.65%
Long Term Debt 6.08 Percent Series, Due 2028 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.08%
Long Term Debt 5.55 Percent Series, Due 2036 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.55%
Long Term Debt 3.671% Series, Year Due, 2042 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.671%
Long Term debt 4.752% Series, Year Due 2044 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.752%
Wis Gas Debenture due September 30, 2025 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.53%
Debentures (unsecured), 5.90% due 2035 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.90%
Debentures (unsecured), 3.71% due 2046 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.71%
Fixed First and Refunding Mortgage XX Series 2.21 Percent Bonds, Due 2016 [Member]
Debt Instrument, Interest Rate, Stated Percentage	2.21%
Fixed First and Refunding Mortgage TT Series 8 Percent Bonds, Due 2018 [Member]
Debt Instrument, Interest Rate, Stated Percentage	8.00%
Fixed First and Refunding Mortgage UU Series 4.63 Percent Bonds, Due 2019 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.63%
Fixed First and Refunding Mortgage VV Series 3.900 Percent Bonds, Due 2030 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.90%
Fixed First and Refunding Mortgage WW Series 1.875 Percent Bonds, Due 2033 [Member]
Debt Instrument, Interest Rate, Stated Percentage	1.875%
First and Refunding Mortgage Bonds, Series ZZ, 4.0% bonds due 2033 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.00%
Fixed First and Refunding Mortgage RR Series 4.3 Percent Bonds, Due 2035 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.30%
Fixed First and Refunding Mortgage YY Series 3.98 Percent Bonds Due 2042 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.98%
First and Refunding Mortgage Bonds, Series AAA, 3.96% bonds due 2043 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.96%
First and Refunding Mortgage Bonds, Series BBB, 4.21% bonds due 2044 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.21%
Bonds, Series CCC, 3.65%, due 2046 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.65%
Bonds, Series DDD, 3.65%, due 2046 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.65%
First Mortgage Bonds P Series 3.43 Percent Bonds [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.43%
First Mortgage Series Q, 3.96% bonds due 2043 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.96%
Notes (secured, nonrecourse), 4.91% due 2015-2030 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.91%
Notes (secured, nonrecourse), 5.209% due 2015-2030 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.209%
Notes (secured, nonrecourse), 4.673% due 2015-2031 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.673%
Notes (secured, nonrecourse), 6.00% due 2015-2033 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Notes (secured, nonrecourse), 6.09% due 2030-2040 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.09%
Notes (secured, nonrecourse), 5.848% due 2031-2041 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.848%
Notes (unsecured), 6.94% due 2028 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.94%
Unsecured Senior Notes 8 Percent, Due 2016 [Member]
Debt Instrument, Interest Rate, Stated Percentage	8.00%
Unsecured Senior Notes 4.17 Percent, Due 2020 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.17%
TEG Junior Subordinated Notes, 6.11% due 2066 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.05%	6.11%
TEG Junior Subordinated Notes, 6.00% due 2073 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Notes (secured, nonrecourse), 4.81% effective rate due 2030 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.81%
WEC Energy Group
Common equity	$ 8,929.8	$ 8,654.8
WEC Energy Group | WEC Senior Notes due June 15, 2018 [Member]
Long-Term debt, Unsecured	300.0	300.0
WEC Energy Group | WEC Senior Notes due June 15, 2020 [Member]
Long-Term debt, Unsecured	400.0	400.0
WEC Energy Group | WEC Senior Notes due June 15, 2025 [Member]
Long-Term debt, Unsecured	$ 500.0	500.0
WEC Energy Group | Notes (unsecured), 6.20% due 2033 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.20%
Long-Term debt, Unsecured	$ 200.0	200.0
WEC Energy Group | Junior Notes (unsecured), 6.25% due 2067 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Long-Term debt, Unsecured	$ 500.0	500.0
WE | Debentures (unsecured), 1.70% due 2018 [Member]
Long-Term debt, Unsecured	250.0	250.0
WE | Debentures (unsecured), 4.25% due 2019 [Member]
Long-Term debt, Unsecured	250.0	250.0
WE | Debentures (unsecured) 2.95% due 2021 [Member]
Long-Term debt, Unsecured	300.0	300.0
WE | Wis Elec Debenture due June 1, 2025 [Member]
Long-Term debt, Unsecured	250.0	250.0
WE | Debentures (unsecured), 6-1/2% due 2028 [Member]
Long-Term debt, Unsecured	150.0	150.0
WE | Debentures (unsecured), 5.625% due 2033 [Member]
Long-Term debt, Unsecured	335.0	335.0
WE | Debentures (unsecured), 5.70% due 2036 [Member]
Long-Term debt, Unsecured	300.0	300.0
WE | Debentures (unsecured), 3.65% due 2042 [Member]
Long-Term debt, Unsecured	250.0	250.0
WE | Debentures (unsecured), 4.25% due 2044 [Member]
Long-Term debt, Unsecured	250.0	250.0
WE | Wis Elec Debenture due December 15, 2045 [Member]
Long-Term debt, Unsecured	250.0	250.0
WE | Debentures (unsecured), 6-7/8% due 2095 [Member]
Long-Term debt, Unsecured	100.0	100.0
WG | Wis Gas Debenture due September 30, 2025 [Member] [Member]
Long-Term debt, Unsecured	200.0	200.0
WG | Debentures (unsecured), 5.90% due 2035 [Member]
Long-Term debt, Unsecured	90.0	90.0
WG | Debentures (unsecured), 3.71% due 2046 [Member]
Long-Term debt, Unsecured	200.0	0.0
WPS | Long Term Debt 5.65 Percent Series, Due 2017 [Member]
Long-Term debt, Unsecured	125.0	125.0
WPS | Long Term Debt 1.65% Series, Due 2018 [Member]
Long-Term debt, Unsecured	250.0	250.0
WPS | Long Term Debt 6.08 Percent Series, Due 2028 [Member]
Long-Term debt, Unsecured	50.0	50.0
WPS | Long Term Debt 5.55 Percent Series, Due 2036 [Member]
Long-Term debt, Unsecured	125.0	125.0
WPS | Long Term Debt 3.671% Series, Year Due, 2042 [Member]
Long-Term debt, Unsecured	300.0	300.0
WPS | Long Term debt 4.752% Series, Year Due 2044 [Member]
Long-Term debt, Unsecured	450.0	450.0
PGL | Fixed First and Refunding Mortgage XX Series 2.21 Percent Bonds, Due 2016 [Member]
Long-Term debt, Secured	0.0	50.0
PGL | Fixed First and Refunding Mortgage TT Series 8 Percent Bonds, Due 2018 [Member]
Long-Term debt, Secured	5.0	5.0
PGL | Fixed First and Refunding Mortgage UU Series 4.63 Percent Bonds, Due 2019 [Member]
Long-Term debt, Secured	75.0	75.0
PGL | Fixed First and Refunding Mortgage VV Series 3.900 Percent Bonds, Due 2030 [Member]
Long-Term debt, Secured	50.0	50.0
PGL | Fixed First and Refunding Mortgage WW Series 1.875 Percent Bonds, Due 2033 [Member]
Long-Term debt, Secured	50.0	50.0
PGL | First and Refunding Mortgage Bonds, Series ZZ, 4.0% bonds due 2033 [Member]
Long-Term debt, Secured	50.0	50.0
PGL | Fixed First and Refunding Mortgage RR Series 4.3 Percent Bonds, Due 2035 [Member]
Long-Term debt, Secured	0.0	50.0
PGL | Fixed First and Refunding Mortgage YY Series 3.98 Percent Bonds Due 2042 [Member]
Long-Term debt, Secured	100.0	100.0
PGL | First and Refunding Mortgage Bonds, Series AAA, 3.96% bonds due 2043 [Member]
Long-Term debt, Secured	220.0	220.0
PGL | First and Refunding Mortgage Bonds, Series BBB, 4.21% bonds due 2044 [Member]
Long-Term debt, Secured	200.0	200.0
PGL | Bonds, Series CCC, 3.65%, due 2046 [Member]
Long-Term debt, Secured	50.0	0.0
PGL | Bonds, Series DDD, 3.65%, due 2046 [Member]
Long-Term debt, Secured	150.0	0.0
NSG | First Mortgage Bonds P Series 3.43 Percent Bonds [Member]
Long-Term debt, Secured	28.0	28.0
NSG | First Mortgage Series Q, 3.96% bonds due 2043 [Member]
Long-Term debt, Secured	$ 54.0	54.0
We Power | Notes (secured, nonrecourse), 4.91% due 2015-2030 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.91%
Long-Term debt, Secured	$ 106.7	112.1
We Power | Notes (secured, nonrecourse), 5.209% due 2015-2030 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.209%
Long-Term debt, Secured	$ 204.8	215.0
We Power | Notes (secured, nonrecourse), 4.673% due 2015-2031 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.673%
Long-Term debt, Secured	$ 170.9	178.3
We Power | Notes (secured, nonrecourse), 6.00% due 2015-2033 [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Long-Term debt, Secured	$ 126.1	130.5
We Power | Notes (secured, nonrecourse), 6.09% due 2030-2040 [Member]
Long-Term debt, Secured	275.0	275.0
We Power | Notes (secured, nonrecourse), 5.848% due 2031-2041 [Member]
Long-Term debt, Secured	215.0	215.0
WECC | Notes (unsecured), 6.94% due 2028 [Member]
Long-Term debt, Unsecured	50.0	50.0
Integrys Holding Inc | Unsecured Senior Notes 8 Percent, Due 2016 [Member]
Long-Term debt, Unsecured	0.0	50.0
Integrys Holding Inc | Unsecured Senior Notes 4.17 Percent, Due 2020 [Member]
Long-Term debt, Unsecured	250.0	250.0
Integrys Holding Inc | TEG Junior Subordinated Notes, 6.11% due 2066 [Member]
Long-Term debt, Unsecured	$ 114.9	269.8
Integrys Holding Inc | TEG Junior Subordinated Notes, 6.00% due 2073 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Long-Term debt, Unsecured	$ 400.0	400.0
Bostco | Notes (secured, nonrecourse), 4.81% effective rate due 2030 [Member]
Long-Term debt, Secured	2.0	2.0
Total Common Shareholders' Equity
Common equity	$ 8,929.8	$ 8,654.8