Income Taxes Income Taxes (Tables)

6 Months Ended

Jun. 30, 2019

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The following table summarizes the significant factors impacting the difference between our effective tax rate and the federal statutory rate for the three and six months ended June 30 (dollars in thousands):

	Three months ended June 30,										Six months ended June 30,
	2019					2018					2019					2018
Federal income taxes at statutory rates	$	4,874		21.0	%	$	6,479		21.0	%	$	35,513		21.0	%	$	20,269		21.0	%
Increase (decrease) in tax resulting from:
Tax effect of regulatory treatment of utility plant differences	(2,139		)	(9.2	)	(1,981		)	(6.4	)	(4,219		)	(2.5	)	(2,999		)	(3.1	)
State income tax expense	(8		)	—		60			0.2		1,651			1.0		1,024			1.1
Acquisition costs	112			0.5		73			0.2		(1,712		)	(1.0	)	119			0.1
Non-plant excess deferred turnaround (1)	(5,091		)	(21.9	)	(11		)	—		(5,601		)	(3.3	)	(11		)	—
Tax loss on sale of METALfx	(1,259		)	(5.4	)	—			—		(1,259		)	(0.8	)	—			—
Valuation allowance	1,245			5.3		—			—		1,245			0.7		—			—
Settlement of equity awards	—			—		—			—		612			0.4		(990		)	(1.0	)
Other	525			2.2		589			1.9		2,046			1.2		(1,493		)	(1.6	)
Total income tax expense (benefit)	$	(1,741	)	(7.5	)%	$	5,209		16.9	%	$	28,276		16.7	%	$	15,919		16.5	%

(1)

In March 2019, the IPUC approved an all-party settlement agreement related to electric tax benefits that were set aside for Colstrip in the 2017 general rate case order. In the approved settlement agreement, the parties agreed to utilize approximately $6.4 million ($5.1 million when tax-effected) of the electric tax benefits to offset costs associated with accelerating the depreciation of Colstrip Units 3 & 4, to reflect a remaining useful life of those units through December 31, 2027. In the second quarter 2019, the Company recorded a one-time charge to depreciation expense with an offsetting amount included in income tax expense.