REGULATORY ASSETS AND LIABILITIES (Notes)

3 Months Ended

Mar. 31, 2015

SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]

Schedule of Regulatory Assets and Liabilities

2. REGULATORY ASSETS AND LIABILITIES

The tables below present a summary of regulatory assets, net of amortization, and liabilities for the periods indicated:

	March 31, 2015
	Current			Noncurrent			Total
	(Thousands of dollars)
Pension and postretirement benefit costs (see Note 7)	$	20,218		$	453,382		$	473,600
Reacquired debt costs	812			9,527			10,339
Other	1,292			2,140			3,432
Total regulatory assets, net of amortization	22,322			465,049			487,371
Accumulated removal costs (a)	—			(15,038		)	(15,038		)
Weather normalization	(8,740		)	—			(8,740		)
Over-recovered purchased-gas costs	(44,015		)	—			(44,015		)
Ad valorem tax	(1,497		)	—			(1,497		)
Total regulatory liabilities	(54,252		)	(15,038		)	(69,290		)
Net regulatory assets (liabilities)	$	(31,930	)	$	450,011		$	418,081

(a) Included in other deferred credits in our Balance Sheets.

	December 31, 2014
	Current			Noncurrent			Total
	(Thousands of dollars)
Under-recovered purchased-gas costs	$	28,712		$	—		$	28,712
Pension and postretirement benefit costs	18,108			466,684			484,792
Reacquired debt costs	812			9,730			10,542
Other	2,561			2,309			4,870
Total regulatory assets, net of amortization	50,193			478,723			528,916
Accumulated removal costs (a)	—			(15,451		)	(15,451		)
Weather normalization	(16,516		)	—			(16,516		)
Over-recovered purchased-gas costs	(13,055		)	—			(13,055		)
Ad valorem tax	(2,896		)	—			(2,896		)
Total regulatory liabilities	(32,467		)	(15,451		)	(47,918		)
Net regulatory assets (liabilities)	$	17,726		$	463,272		$	480,998

(a) Included in other deferred credits in our Balance Sheets.

Regulatory assets on our Balance Sheets, as authorized by the various regulatory commissions, are probable of recovery. Base rates are designed to provide a recovery of costs during the period rates are in effect, but do not generally provide for a return on investment for amounts we have deferred as regulatory assets. All of our regulatory assets recoverable through base rates are subject to review by the respective regulatory authorities during future rate proceedings. We are not aware of any evidence that these costs will not be recoverable through either riders or base rates, and we believe that we will be able to recover such costs, consistent with our historical recoveries.

Purchased-gas costs include the costs that have been over- or under-recovered from customers through the purchased-gas cost adjustment mechanisms and also include natural gas utilized in our operations, premiums paid and any cash settlements received from our purchased natural gas call options.