REGULATORY ASSETS AND LIABILITIES (Tables)

12 Months Ended

Dec. 31, 2018

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



		December 31, 2018
	Remaining Recovery Period	Current			Noncurrent			Total
		(Thousands of dollars)
Under-recovered purchased-gas costs	1 year	$	25,083		$	—		$	25,083
Pension and other postemployment benefit costs	See Note 12	23,384			421,726			445,110
Reacquired debt costs	9 years	812			6,487			7,299
MGP remediation costs	15 years	—			7,724			7,724
Ad-valorem tax	1 year	1,070			—			1,070
Other	1 to 20 years	4,071			1,542			5,613
Total regulatory assets, net of amortization		54,420			437,479			491,899
Federal income tax rate changes (a)	See Note 13	(30,934		)	(520,866		)	(551,800		)
Over-recovered purchased-gas costs	1 year	(13,668		)	—			(13,668		)
Weather normalization	1 year	(3,792		)	—			(3,792		)
Total regulatory liabilities		(48,394		)	(520,866		)	(569,260		)
Net regulatory assets and liabilities		$	6,026		$	(83,387	)	$	(77,361	)

(a) See Note 13 for additional information regarding our federal income tax rate changes regulatory liabilities.



		December 31, 2017
	Remaining Recovery Period	Current			Noncurrent			Total
		(Thousands of dollars)
Under-recovered purchased-gas costs	1 year	$	41,238		$	—		$	41,238
Pension and other postemployment benefit costs	See Note 12	25,156			387,582			412,738
Weather normalization	1 year	17,461			—			17,461
Reacquired debt costs	10 years	812			7,298			8,110
MGP remediation costs	15 years	—			6,104			6,104
Other	1 to 21 years	3,513			4,205			7,718
Total regulatory assets, net of amortization		88,180			405,189			493,369
Federal income tax rate changes (a)	See Note 13	—			(519,421		)	(519,421		)
Over-recovered purchased-gas costs	1 year	(9,434		)	—			(9,434		)
Ad-valorem tax	1 year	(4		)	—			(4		)
Total regulatory liabilities		(9,438		)	(519,421		)	(528,859		)
Net regulatory assets and liabilities		$	78,742		$	(114,232	)	$	(35,490	)