Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Guarantees Issued and Outstanding

The following table presents the guarantee issued and outstanding for NSP-Wisconsin:

(Millions of Dollars)	March 31, 2018		Dec. 31, 2017
Guarantee issued and outstanding	$	1.0	$	1.0
Current exposure under this guarantee	—		—