Income Taxes Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Effective tax rate reconciliation
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ 72,771	$ 60,221
Income tax calculated at federal statutory rate	15,282	12,646
State income tax, net of federal provisions	959	400
Flow-through repairs deductions	(5,845)	(6,801)
Production tax credits	3,199	3,824
Amortization of excess deferred income tax	(799)	(411)
Reduction to previously claimed alternative minimum tax credit	3,186	0
Plant and depreciation of flow-through items	688	(255)
Share-based compensation	388	(253)
Other, net	(419)	(391)
Total Other Reconciling Items	(5,041)	(11,535)
Income tax expense	$ 10,241	$ 1,111
Income tax calculated at federal statutory rate	21.00%	21.00%
State income tax, net of federal provisions	1.30%	0.70%
Flow-through repairs deductions	(8.00%)	(11.30%)
Production tax credits	(4.40%)	(6.40%)
Reduction to previously claimed alternative minimum tax credit	4.40%	0.00%
Amortization of excess deferred income tax	(1.10%)	(0.70%)
Plant and depreciation of flow-through items	0.90%	(0.40%)
Share-based compensation	0.50%	(0.40%)
Other, net	(0.50%)	(0.70%)
Total Other Reconciling Items	(6.90%)	(19.20%)
Income tax expense	14.10%	1.80%