Income Taxes (Tables)

9 Months Ended

Sep. 30, 2016

Income Tax Disclosure [Abstract]

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

The following table summarizes the significant differences in income tax expense based on the differences between our effective tax rate and the federal statutory rate (in thousands):

	Three Months Ended September 30,
	2016					2015
Income Before Income Taxes	$	34,946				$	30,187
Income tax calculated at 35% federal statutory rate	12,231			35.0	%	10,565			35.0	%
Permanent or flow through adjustments:
State income, net of federal provisions	(615		)	(1.8	)	(857		)	(2.8	)
Flow-through repairs deductions	(18,995		)	(54.4	)	(2,779		)	(9.2	)
Production tax credits	(2,218		)	(6.3	)	(733		)	(2.4	)
Plant and depreciation of flow through items	(243		)	(0.7	)	(374		)	(1.2	)
Prior year permanent return to accrual adjustments	—			—		1,025			3.4
Other, net	181			0.6		(458		)	(1.6	)
	(21,890		)	(62.6	)	(4,176		)	(13.8	)
	$	(9,659	)	(27.6	)%	$	6,389		21.2	%

	Nine Months Ended September 30,
	2016					2015
Income Before Income Taxes	$	113,988				$	130,812
Income tax calculated at 35% federal statutory rate	39,896			35.0	%	45,784			35.0	%
Permanent or flow through adjustments:
State income, net of federal provisions	(2,740		)	(2.4	)	(329		)	(0.3	)
Flow-through repairs deductions	(32,640		)	(28.6	)	(17,240		)	(13.2	)
Production tax credits	(7,317		)	(6.4	)	(2,645		)	(2.0	)
Plant and depreciation of flow through items	(1,427		)	(1.3	)	(1,000		)	(0.8	)
Prior year permanent return to accrual adjustments	(128		)	(0.1	)	1,025			0.8
Other, net	116			0.1		(979		)	(0.7	)
	(44,136		)	(38.7	)	(21,168		)	(16.2	)
	$	(4,240	)	(3.7	)%	$	24,616		18.8	%