Income Taxes (Tables)

6 Months Ended

Jun. 30, 2021

Income Tax Disclosure [Abstract]

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

The following table summarizes the differences between our effective tax rate and the federal statutory rate (in thousands):

	Three Months Ended June 30,
	2021				2020
Income Before Income Taxes	$	38,602			$	20,776
Income tax calculated at federal statutory rate	8,107		21.0	%	4,363		21.0	%
Permanent or flow-through adjustments:
State income tax, net of federal provisions	222		0.6		5		0.0
Flow-through repairs deductions	(4,227)		(11.0)		(3,208)		(15.4)
Production tax credits	(2,262)		(5.9)		(1,737)		(8.5)
Plant and depreciation of flow-through items	(184)		(0.5)		59		0.3
Amortization of excess deferred income tax	(143)		(0.4)		(153)		(0.7)
Other, net	(148)		(0.4)		(47)		(0.2)
	(6,742)		(17.6)		(5,081)		(24.5)
Income tax expense (benefit)	$	1,365	3.4	%	$	(718)	(3.5)	%

	Six Months Ended June 30,
	2021				2020
Income Before Income Taxes	$	101,651			$	69,674
Income tax calculated at federal statutory rate	21,347		21.0	%	14,631		21.0	%
Permanent or flow through adjustments:
State income, net of federal provisions	277		0.3		27		0.1
Flow-through repairs deductions	(12,080)		(11.9)		(10,646)		(15.3)
Production tax credits	(6,569)		(6.5)		(5,348)		(7.7)
Plant and depreciation of flow through items	(524)		(0.5)		196		0.3
Amortization of excess deferred income tax	(408)		(0.4)		(509)		(0.7)
Share-based compensation	(261)		(0.3)		(609)		(0.9)
Other, net	(439)		(0.4)		(266)		(0.4)
	(20,004)		(19.7)		(17,155)		(24.6)
Income tax expense (benefit)	$	1,343	1.3	%	$	(2,524)	(3.6)	%