Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2013

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Assets

The components of regulatory assets shown on the consolidated balance sheets of NSP-Wisconsin at Dec. 31, 2013 and 2012 are:

(Thousands of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2013				Dec. 31, 2012
Regulatory Assets			Current		Noncurrent		Current		Noncurrent
Environmental remediation costs	1, 11	Various	$	4,376	$	117,684	$	2,521	$	109,162
Pension and retiree medical obligations (a)	7	Various	8,202		85,220		7,328		104,426
Recoverable deferred taxes on AFUDC recorded in plant	1	Plant lives	—		12,679		—		10,458
Losses on reacquired debt	4	Term of related debt	801		5,737		800		6,538
State commission adjustments	1	Plant lives	410		9,355		339		7,533
Conservation programs	1	Less than one year	404		—		691		—
Deferred income tax adjustment	1, 6	Typically plant lives	—		1,763		—		1,974
Recoverable purchased natural gas and electric energy costs		Less than one year	673		—		358		—
Other		Various	—		755		11		368
Total regulatory assets			$	14,866	$	233,193	$	12,048	$	240,459

^(a)  Includes the non-qualified pension plan.

Regulatory Liabilities

The components of regulatory liabilities shown on the consolidated balance sheets of NSP-Wisconsin at Dec. 31, 2013 and 2012 are:

(Thousands of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2013				Dec. 31, 2012
Regulatory Liabilities			Current		Noncurrent		Current		Noncurrent
Plant removal costs	11	Plant lives	$	—	$	116,293	$	—	$	113,949
DOE settlement	11	Less than one year	6,814		—		5,628		—
Investment tax credit deferrals	1, 6	Various	—		9,976		—		9,626
Conservation programs	1	Less than one year	1,187		—		73		—
Deferred electric production and natural gas costs	1	Less than one year	1,542		—		134		—
Other		Various	174		155		251		171
Total regulatory liabilities			$	9,717	$	126,424	$	6,086	$	123,746