Consolidated Statements of Capitalization (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Common Equity	$ 4,419.7		$ 4,233.0
Preferred Stock	30.4		30.4
Obligations under capital leases	84.5		104.3
Unamortized discount, net and other	(26.4)		(25.6)
Long-term debt due currently	(424.1)		(342.2)
Total Long-Term Debt	4,186.4		4,363.2
Total Capitalization	8,636.5		8,626.6
Debentures (unsecured), 6.00% due 2014 [Member]
Long-Term debt, Unsecured	0		300.0
Debentures (unsecured), 5.20% due 2015 [Member]
Long-Term debt, Unsecured	125.0		125.0
Debentures (unsecured), 6.25% due 2015 [Member]
Long-Term debt, Unsecured	250.0		250.0
Debentures (unsecured), 1.70% due 2018 [Member]
Long-Term debt, Unsecured	250.0		250.0
Debentures (unsecured), 4.25% due 2019 [Member]
Long-Term debt, Unsecured	250.0		250.0
Debentures (unsecured) 2.95% due 2021 [Member]
Long-Term debt, Unsecured	300.0		300.0
Debentures (unsecured), 6-1/2% due 2028 [Member]
Long-Term debt, Unsecured	150.0		150.0
Debentures (unsecured), 5.625% due 2033 [Member]
Long-Term debt, Unsecured	335.0		335.0
Debentures (unsecured), 5.90% due 2035 [Member]
Long-Term debt, Unsecured	90.0		90.0
Notes (secured, nonrecourse), 4.91% due 2014-2030 [Member] [Member]
Long-Term debt, Secured	117.2	[1]	122.1	[1]
Debentures (unsecured), 5.70% due 2036 [Member]
Long-Term debt, Unsecured	300.0		300.0
Debentures (unsecured), 3.65% due 2042 [Member]
Long-Term debt, Unsecured	250.0		250.0
Debentures (unsecured), 4.25% due 2044 [Member]
Long-Term debt, Unsecured	250.0		0
Debentures (unsecured), 6-7/8% due 2095 [Member]
Long-Term debt, Unsecured	100.0		100.0
Notes (secured, nonrecourse), 4.81% effective rate due 2030 [Member]
Long-Term debt, Secured	2.0		2.0
Notes (secured, nonrecourse), 5.209% due 2014-2030 [Member] [Member]
Long-Term debt, Secured	223.9	[2]	231.5	[2]
Notes (secured, nonrecourse), 4.673% due 2014-2031 [Member] [Member]
Long-Term debt, Secured	184.7	[2]	190.9	[2]
Notes (secured, nonrecourse), 6.00% due 2014-2033 [Member] [Member]
Long-Term debt, Secured	134.6	[1]	138.4	[1]
Notes (secured, nonrecourse), 6.09% due 2030-2040 [Member]
Long-Term debt, Secured	275.0	[2]	275.0	[2]
Notes (secured, nonrecourse), 5.848% due 2031-2041 [Member]
Long-Term debt, Secured	215.0	[2]	215.0	[2]
Notes (secured, nonrecourse) 6.00% due 2021 [Member]
Long-Term debt, Secured	0		1.8
Notes (unsecured), 6.94% due 2028 [Member]
Long-Term debt, Unsecured	50.0		50.0
Notes (unsecured), 6.20% due 2033 [Member]
Long-Term debt, Unsecured	200.0		200.0
Junior Notes (unsecured), 6.25% due 2067 [Member]
Long-Term debt, Unsecured	500.0		500.0
Wisconsin Energy Corporation [Member]
Preferred Stock	0		0
Wisconsin Electric [Member]
Preferred Stock	30.4		30.4
Long-Term debt, Unsecured	147.0
Six Per Cent. Preferred Stock [Member]
Preferred Stock	4.4
Six Per Cent. Preferred Stock [Member] | Wisconsin Electric [Member]
Preferred Stock			4.4
Serial preferred stock, 3.60% Series Redeemable [Member]
Preferred Stock	26.0
Serial preferred stock, 3.60% Series Redeemable [Member] | Wisconsin Electric [Member]
Preferred Stock			26.0
Serial preferred stock, $25 par value; authorized 5,000,000 shares; none outstanding [Member]
Preferred Stock	0
Serial preferred stock, $25 par value; authorized 5,000,000 shares; none outstanding [Member] | Wisconsin Electric [Member]
Preferred Stock			$ 0

[1] (a) Senior notes are secured by a collateral assignment of the leases between PWGS and Wisconsin Electric related to PWGS 1 and 2.

[2] (b) Senior notes are secured by a collateral assignment of the leases between ERGSS and Wisconsin Electric related to OC 1 and 2.