REGULATORY ASSETS AND LIABILITIES (Tables)

9 Months Ended

Sep. 30, 2018

SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]

SCHEDULE OF REGULATED ASSETS AND LIABILITIES

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

	September 30, 2018
	Current			Noncurrent			Total
	(Thousands of dollars)
Under-recovered purchased-gas costs	$	16,727		$	—		$	16,727
Pension and postemployment benefit costs	25,109			357,723			382,832
Reacquired debt costs	812			6,690			7,502
MGP remediation costs	—			7,724			7,724
Ad valorem tax	1,029			—			1,029
Other	5,362			2,922			8,284
Total regulatory assets, net of amortization	49,039			375,059			424,098
Federal income tax rate changes (a)	(19,447		)	(521,717		)	(541,164		)
Over-recovered purchased-gas costs	(22,218		)	—			(22,218		)
Total regulatory liabilities	(41,665		)	(521,717		)	(563,382		)
Net regulatory assets (liabilities)	$	7,374		$	(146,658	)	$	(139,284	)

(a)See Note 10 for additional information regarding our federal income tax rate changes to regulatory liabilities.

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

(a)See Note 10 for additional information regarding our federal income tax rate changes to regulatory liabilities.