Consolidated Statements of Capitalization (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Debentures (unsecured), 4.50% due 2013 [Member]
Debt instrument stated interest rate (percentage)	4.50%	4.50%
Debentures (unsecured), 6.60% due 2013 [Member]
Debt instrument stated interest rate (percentage)	6.60%	6.60%
Debentures (unsecured), 6.00% due 2014 [Member]
Debt instrument stated interest rate (percentage)	6.00%	6.00%
Debentures (unsecured), 5.20% due 2015 [Member]
Debt instrument stated interest rate (percentage)	5.20%	5.20%
Debentures (unsecured), 6.25% due 2015 [Member]
Debt instrument stated interest rate (percentage)	6.25%	6.25%
Debentures (unsecured), 4.25% due 2019 [Member]
Debt instrument stated interest rate (percentage)	4.25%	4.25%
Debentures (unsecured) 2.95% due 2021 [Member]
Debt instrument stated interest rate (percentage)	2.95%	2.95%
Debentures (unsecured), 6-1/2% due 2028 [Member]
Debt instrument stated interest rate (percentage)	6.50%	6.50%
Debentures (unsecured), 5.625% due 2033 [Member]
Debt instrument stated interest rate (percentage)	5.625%	5.625%
Debentures (unsecured), 5.90% due 2035 [Member]
Debt instrument stated interest rate (percentage)	5.90%	5.90%
Debentures (unsecured), 5.70% due 2036 [Member]
Debt instrument stated interest rate (percentage)	5.70%	5.70%
Debentures (unsecured), 6-7/8% due 2095 [Member]
Debt instrument stated interest rate (percentage)	6.875%	6.875%
Notes (secured, nonrecourse), 4.81% effective rate due 2030 [Member]
Debt instrument stated interest rate (percentage)	4.81%	4.81%
Notes (secured, nonrecourse), 4.91% due 2010-2030 [Member]
Debt instrument stated interest rate (percentage)	4.91%	4.91%
Notes (secured, nonrecourse), 5.209% due 2010-2030 [Member]
Debt instrument stated interest rate (percentage)	5.209%	5.209%
Notes (secured, nonrecourse), 4.673% due 2011-2031 [Member]
Debt instrument stated interest rate (percentage)	4.673%	4.673%
Notes (secured, nonrecourse), 6.00% due 2011-2033 [Member]
Debt instrument stated interest rate (percentage)	6.00%	6.00%
Notes (secured, nonrecourse), 6.09% due 2030-2040 [Member]
Debt instrument stated interest rate (percentage)	6.09%	6.09%
Notes (secured, nonrecourse), 5.848% due 2031-2041 [Member]
Debt instrument stated interest rate (percentage)	5.848%	5.848%
Notes (unsecured), 6.50% due 2011 [Member]
Debt instrument stated interest rate (percentage)	6.50%	6.50%
Notes (unsecured), 6.51% due 2013 [Member]
Debt instrument stated interest rate (percentage)	6.51%	6.51%
Notes (unsecured), 6.94% due 2028 [Member]
Debt instrument stated interest rate (percentage)	6.94%	6.94%
Notes (unsecured), 0.504% variable rate due 2016 [Member]
Long-term debt, percentage bearing variable interest rate	0.504%	0.504%
Notes (unsecured), 0.504% variable rate due 2030 [Member]
Long-term debt, percentage bearing variable interest rate	0.504%	0.504%
Notes (unsecured), 6.20% due 2033 [Member]
Debt instrument stated interest rate (percentage)	6.20%	6.20%
Junior Notes (unsecured), 6.25% due 2067 [Member]
Debt instrument stated interest rate (percentage)	6.25%	6.25%
Wisconsin Energy Corporation [Member]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	15,000,000	15,000,000
Preferred stock, shares outstanding	0	0
Wisconsin Electric [Member]
Preferred stock, par value	$ 25	$ 25
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares outstanding	0	0
Six Per Cent. Preferred Stock [Member] | Wisconsin Electric [Member]
Preferred stock, par value	$ 100	$ 100
Preferred stock, shares authorized	45,000	45,000
Preferred stock, shares outstanding	44,498	44,498
Preferred stock dividend rate, percentage	6.00%	6.00%
Serial preferred stock, 3.60% Series Redeemable [Member] | Wisconsin Electric [Member]
Preferred stock, par value	$ 100	$ 100
Preferred stock, shares authorized	2,286,500	2,286,500
Preferred stock, shares outstanding	260,000	260,000
Preferred stock dividend rate, percentage	3.60%	3.60%
Preferred stock, redeemable per share	$ 101	$ 101