REGULATORY ASSETS AND LIABILITIES (Notes)

6 Months Ended

Jun. 30, 2017

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:

	June 30, 2017
	Current			Noncurrent		Total
	(Thousands of dollars)
Under-recovered purchased-gas costs	$	26,500		$	—	$	26,500
Pension and postemployment benefit costs	31,498			408,593		440,091
Weather normalization	20,311			—		20,311
Reacquired debt costs	812			7,703		8,515
Other	3,181			4,798		7,979
Total regulatory assets, net of amortization	82,302			421,094		503,396
Over-recovered purchased-gas costs	(14,049		)	—		(14,049		)
Ad valorem tax	(606		)	—		(606		)
Total regulatory liabilities (a)	(14,655		)	—		(14,655		)
Net regulatory assets (liabilities)	$	67,647		$	421,094	$	488,741

(a) Included in other current liabilities in our Balance Sheets.

	December 31, 2016
	Current			Noncurrent		Total
	(Thousands of dollars)
Under-recovered purchased-gas costs	$	29,901		$	—	$	29,901
Pension and postemployment benefit costs	31,498			427,448		458,946
Weather normalization	17,661			—		17,661
Reacquired debt costs	812			8,108		8,920
Other	3,274			4,966		8,240
Total regulatory assets, net of amortization	83,146			440,522		523,668
Over-recovered purchased-gas costs	(10,154		)	—		(10,154		)
Ad valorem tax	(1,768		)	—		(1,768		)
Total regulatory liabilities (a)	(11,922		)	—		(11,922		)
Net regulatory assets (liabilities)	$	71,224		$	440,522	$	511,746

(a) Included in other current liabilities in our Balance Sheets.

Regulatory assets on our Balance Sheets, as authorized by various regulatory authorities, 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 are subject to review by the respective regulatory authorities during future regulatory 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.