Regulatory Assets and Liabilities

12 Months Ended

Dec. 31, 2019

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Assets and Liabilities

Regulatory assets and liabilities are created for amounts that regulators may allow to be collected or may require to be paid back to customers in future electric and natural gas rates. NSP-Wisconsin would be required to recognize the write-off of regulatory assets and liabilities in net income or other comprehensive income if changes in the utility industry no longer allow for the application of regulatory accounting guidance under GAAP.

Components of regulatory assets:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2019				Dec. 31, 2018
Regulatory Assets			Current		Noncurrent		Current		Noncurrent
Environmental remediation costs	1, 10	Various	$	35.2	$	107.9	$	16.0	$	135.2
Pension and retiree medical obligations	9	Various	11.8		69.8		5.5		85.1
State commission adjustments		Plant lives	0.9		18.6		0.8		16.8
Recoverable deferred taxes on AFUDC recorded in plant		Plant lives	—		17.1		—		16.9
Losses on reacquired debt		Term of related debt	0.2		2.3		0.2		2.4
Excess deferred taxes — TCJA	7	Various	23.4		—		—		25.2
Other		Various	0.4		8.7		0.1		3.9
Total regulatory assets			$	71.9	$	224.4	$	22.6	$	285.5

Components of regulatory liabilities:

(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2019				Dec. 31, 2018
Regulatory Liabilities			Current		Noncurrent		Current		Noncurrent
Deferred income tax adjustments and TCJA refunds (a)	7	Various	$	51.0	$	195.9	$	0.2	$	238.3
Plant removal costs	1, 10	Plant lives	—		171.2		—		157.7
Deferred electric production and natural gas costs		Less than one year	17.4		—		13.4		—
United States Department of Energy settlement		Less than one year	9.7		—		6.2		—
Other		Various	0.8		3.7		1.1		4.1
Total regulatory liabilities			$	78.9	$	370.8	$	20.9	$	400.1

^(a)  Includes the revaluation of recoverable/regulated plant ADIT and revaluation impact of non-plant ADIT due to the TCJA.

At Dec. 31, 2019 and 2018, NSP-Wisconsin’s regulatory assets not earning a return primarily included the unfunded portion of pension and retiree medical obligations. In addition, regulatory assets included $7.4 million and $7.6 million at Dec. 31, 2019 and 2018, respectively, of past expenditures not earning a return. Amounts related to funded pension obligations.