Borrowings and Other Financing Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Borrowings and Other Financing Instruments [Abstract]

Credit Facilities

At Dec. 31, 2017, NSP-Wisconsin had the following committed credit facility available (in millions):

Credit Facility (a)		Drawn(b)		Available
$	150	$	11	$	139

^(a)  This credit facility matures in June 2021.

^(b)  Includes outstanding commercial paper.

Commercial Paper

Borrowings and Other Financing Instruments [Abstract]

Short-term Borrowings

Commercial paper outstanding for NSP-Wisconsin was as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended Dec. 31, 2017
Borrowing limit	$	150
Amount outstanding at period end	11
Average amount outstanding	70
Maximum amount outstanding	129
Weighted average interest rate, computed on a daily basis	1.38		%
Weighted average interest rate at period end	1.73

(Amounts in Millions, Except Interest Rates)	Twelve Months Ended Dec. 31, 2017			Twelve Months Ended Dec. 31, 2016			Twelve Months Ended Dec. 31, 2015
Borrowing limit	$	150		$	150		$	150
Amount outstanding at period end	11			60			10
Average amount outstanding	52			15			39
Maximum amount outstanding	129			64			122
Weighted average interest rate, computed on a daily basis	1.23		%	0.69		%	0.44		%
Weighted average interest rate at period end	1.73			0.95			0.70

Notes Payable, Other Payables

Borrowings and Other Financing Instruments [Abstract]

Short-term Borrowings

The following table presents the notes payable of Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, to Xcel Energy Inc.:

(Amounts in Millions, Except Interest Rates)	Dec. 31, 2017			Dec. 31, 2016
Notes payable to affiliates	$	0.5		$	0.5
Weighted average interest rate	1.73		%	0.95		%