INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

The components of income tax expense were as follows:

Year Ended December 31,	2016			2015			2014
(millions)
Current:
Federal	$	1.2		$	(16.0	)	$	(11.9	)
State	0.2			(2.0		)	(1.9		)
Total current expense (benefit)	1.4			(18.0		)	(13.8		)
Deferred:
Federal	29.9			48.8			42.4
State	5.9			4.2			3.6
Investment tax credits	(0.1		)	(0.2		)	(0.2		)
Total deferred expense	35.7			52.8			45.8
Total income tax expense	$	37.1		$	34.8		$	32.0

Schedule of Effective Income Tax Rate Reconciliation

The difference between the statutory federal income tax rate and Questar Gas' effective income tax rate is explained as follows:

Year Ended December 31,	2016		2015		2014
Federal income taxes statutory rate	35.0	%	35.0	%	35.0	%
Increases (reductions) resulting from:
State taxes, net of federal benefit	4.2		1.4		1.3
Amortization of investment tax credits related to rate-regulated assets	(0.1	)	(0.2	)	(0.2	)
Other	0.2		(1.1	)	0.6
Effective income tax rate	39.3	%	35.1	%	36.7	%

Schedule of Deferred Tax Assets and Liabilities

Significant components of Questar Gas' deferred income taxes were as follows:

At December 31,	2016			2015
(millions)
Deferred income taxes:
Total deferred income tax assets	$	2.0		$	3.4
Total deferred income tax liabilities	477.8			440.1
Total deferred income tax liabilities	475.8			436.7
Total deferred income taxes:
Property, plant and equipment	$	448.2		$	403.0
Employee benefits	27.9			28.0
Deferred compensation	(0.6		)	(0.9		)
Purchased gas costs	0.1			8.5
Other	0.2			(1.9		)
Total net deferred income tax liabilities	475.8			436.7