INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2019

Income tax [Line Items]

Reconciliation of Income Tax Provision

The following table sets forth our provision for income taxes for the periods indicated:

	Years Ended December 31,
	2019		2018		2017
	(Thousands of dollars)
Current income tax provision
Federal	$	24,537	$	—	$	—
State	5,008		289		750
Total current income tax provision	29,545		289		750
Deferred income tax provision
Federal	8,375		42,413		83,138
State	4,932		10,829		9,255
Total deferred income tax provision	13,307		53,242		92,393
Total provision for income taxes	$	42,852	$	53,531	$	93,143

Schedule of Effective Income Tax Rate Reconciliation

The following table is a reconciliation of our income tax provision for the periods indicated:

	Years Ended December 31,
	2019			2018			2017
	(Thousands of dollars)
Income before income taxes	$	229,601		$	225,765		$	256,138
Federal statutory income tax rate	21		%	21		%	35		%
Provision for federal income taxes	48,215			47,411			89,648
State income taxes, net of federal tax benefit	9,758			8,783			6,503
EDIT not recovered in rates	—			74			2,162
Amortization of EDIT regulatory liability	(12,828		)	—			—
Tax benefit of employee share-based compensation	(2,116		)	(2,770		)	(5,162		)
Other, net	(177		)	33			(8		)
Total provision for income taxes	$	42,852		$	53,531		$	93,143

Schedule of Deferred Tax Assets and Liabilities

The following table sets forth the tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities for the periods indicated:

	December 31,
	2019		2018
	(Thousands of dollars)
Deferred tax assets
Employee benefits and other accrued liabilities	$	32,036	$	48,243
Regulatory adjustments for enacted tax rate changes	124,680		129,201
Net operating loss	752		2,778
Lease obligation basis	8,599		—
Other	2,772		34
Total deferred tax assets	168,839		180,256
Deferred tax liabilities
Excess of tax over book depreciation	742,860		717,903
Purchased-gas cost adjustment	3,556		8,981
Other regulatory assets and liabilities, net	96,456		105,798
Right-of-use asset basis	8,599		—
Total deferred tax liabilities	851,471		832,682
Net deferred tax liabilities	$	682,632	$	652,426