Rate Matters Rate Matters - NSP-Wisconsin (Details) - NSP-Wisconsin - USD ($) $ in Millions		1 Months Ended
	Oct. 26, 2016	Aug. 31, 2016	Jul. 31, 2016	Apr. 30, 2016
PSCW Proceeding - Wisconsin 2017 Electric and Gas Rate Case - Electric Rates 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 17.4
Public Utilities, Requested Rate Increase (Decrease), Percentage				2.40%
Public Utilities, Requested Rate Base, Amount				$ 1,188.0
Public Utilities, Requested Increase Related to Rate Base Investments				11.0
Public Utilities, Requested Increase Related to Generation and Transmission Expenses				6.8
Public Utilities, Requested Increase Related to Fuel and Purchased Power Expenses				11.0
Public Utilities, Total Requested Rate Increase Excluding Refunds				28.8
Public Utilities, Requested Decrease Related to Fuel Refunds				(9.5)
Public Utilities, Requested Decrease Related to Settlement Refund				(1.9)
PSCW Proceeding - Wisconsin 2017 Electric and Gas Rate Case - Gas Rates 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 4.8
Public Utilities, Requested Rate Increase (Decrease), Percentage				3.90%
PSCW Proceeding - Wisconsin 2017 Electric and Gas Rate Case
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage				10.00%
Public Utilities, Percentage of Excess Earnings to be Refunded due to Earnings Cap				100.00%
Public Service Commission of Wisconsin (PSCW) Staff | PSCW Proceeding - Wisconsin 2017 Electric and Gas Rate Case - Electric Rates 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 19.5
Public Utilities, Requested Rate Increase (Decrease), Percentage		2.70%
Public Utilities, Difference Between Filed Request and PSCW Staff Recommendation		$ 7.4
Public Utilities, Requested Increase Related to Rate Base Investments		7.6
Public Utilities, Requested Increase Related to Generation and Transmission Expenses		6.1
Public Utilities, Requested Increase Related to Fuel and Purchased Power Expenses		7.7
Public Utilities, Total Requested Rate Increase Excluding Refunds		21.4
Public Utilities, Requested Decrease Related to Fuel Refunds		0.0
Public Utilities, Requested Decrease Related to Settlement Refund		(1.9)
Public Service Commission of Wisconsin (PSCW) Staff | PSCW Proceeding - Wisconsin 2017 Electric and Gas Rate Case - Gas Rates 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 4.8
Public Utilities, Requested Rate Increase (Decrease), Percentage		3.90%
Public Service Commission of Wisconsin (PSCW) | PSCW Proceeding - Wisconsin 2017 Electric and Gas Rate Case - Electric Rates 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Adjustment to Rate Request Related to Fuel Refund			$ 9.5
Public Utilities, Revised Requested Rate Increase, Amount			$ 29.9
Public Utilities, Revised Requested Rate Increase, Percentage			4.20%
Subsequent Event [Member] | Public Service Commission of Wisconsin (PSCW) | PSCW Proceeding - Wisconsin 2017 Electric and Gas Rate Case - Electric Rates 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 22.5
Public Utilities, Approved Rate Increase (Decrease), Percentage	3.20%
Public Utilities, Approved Increase Related to Rate Base Investments	$ 7.6
Public Utilities, Approved Increase Related to Generation and Transmission Expenses	6.1
Public Utilities, Approved Increase Related to Fuel and Purchased Power Expenses	10.7
Public Utilities, Total Approved Rate Increase, Excluding Refunds	24.4
Public Utilities, Approved Decrease Related to Fuel Refunds	0.0
Public Utilities, Approved Decrease Related to Settlement Refund	(1.9)
Subsequent Event [Member] | Public Service Commission of Wisconsin (PSCW) | PSCW Proceeding - Wisconsin 2017 Electric and Gas Rate Case - Gas Rates 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 4.8
Public Utilities, Approved Rate Increase (Decrease), Percentage	3.90%