REGULATORY ASSETS AND LIABILITIES (Notes)

6 Months Ended

Jun. 30, 2019

SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]

Schedule of Regulatory Assets and Liabilities

3.

REGULATORY ASSETS AND LIABILITIES

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

	June 30, 2019
	Current			Noncurrent			Total
	(Thousands of dollars)
Under-recovered purchased-gas costs	$	767		$	—		$	767
Pension and postemployment benefit costs	22,966			406,441			429,407
Reacquired debt costs	812			6,082			6,894
Ad valorem tax	2,083			—			2,083
MGP remediation costs	98			9,758			9,856
Other	11,646			2,023			13,669
Total regulatory assets, net of amortization	38,372			424,304			462,676
Federal corporate income tax rate changes (a)	(15,755		)	(508,877		)	(524,632		)
Over-recovered purchased-gas costs	(22,616		)	—			(22,616		)
Weather normalization	(8,163		)	—			(8,163		)
Total regulatory liabilities	(46,534		)	(508,877		)	(555,411		)
Net regulatory liabilities	$	(8,162	)	$	(84,573	)	$	(92,735	)

(a) See Note 11 for additional information regarding our federal corporate income tax rate changes to regulatory liabilities.

	December 31, 2018
	Current			Noncurrent			Total
	(Thousands of dollars)
Under-recovered purchased-gas costs	$	25,083		$	—		$	25,083
Pension and postemployment benefit costs	23,384			421,726			445,110
Reacquired debt costs	812			6,487			7,299
MGP remediation costs	—			7,724			7,724
Ad valorem tax	1,070			—			1,070
Other	4,071			1,542			5,613
Total regulatory assets, net of amortization	54,420			437,479			491,899
Federal corporate income tax rate changes (a)	(30,934		)	(520,866		)	(551,800		)
Over-recovered purchased-gas costs	(13,668		)	—			(13,668		)
Weather normalization	(3,792		)	—			(3,792		)
Total regulatory liabilities	(48,394		)	(520,866		)	(569,260		)
Net regulatory assets (liabilities)	$	6,026		$	(83,387	)	$	(77,361	)

(a) See Note 11 for additional information regarding our federal corporate income tax rate changes to regulatory liabilities.

Regulatory assets in our consolidated balance sheets, as authorized by various regulatory authorities, are probable of recovery. Base rates and certain riders are designed to provide a recovery of costs during the period such 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.