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Income tax expense (benefit) statutory rate versus actual rate (Details 6) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Computed tax at federal statutory rate |  |  |
Computed tax at federal statutory rate | $ 99,775 | $ 83,674 | $ 66,543
Federal statutory rate | 21.00% | 21.00% | 21.00%
Increases (reductions) resulting from: |  |  |
State income taxes, net of federal income tax | $ 17,845 | $ 14,029 | $ 12,190
State income tax, rate | 3.80% | 3.50% | 3.80%
Federal renewable energy credit | $ (16,009) | $ (15,843) | $ (11,759)
Federal renewable energy credit, rate | (3.40%) | (4.00%) | (3.70%)
Tax compliance and uncertain tax positions | $ (3,543) | $ (2,739) | $ (2,725)
Tax compliance and uncertain tax positions, rate | (0.70%) | (0.70%) | (0.90%)
Excess deferred income tax amortization | $ (12,517) | $ (11,904) | $ (9,319)
Excess deferred income tax amortization, rate | (2.60%) | (3.00%) | (2.90%)
TCJA revaluation | $ 0 | $ 0 | $ (5,947)
TCJA revaluation, rate | 0.00% | 0.00% | (1.90%)
TCJA revaluation related to accumulated other comprehensive loss balance | $ 0 | $ 0 | $ (42)
TCJA revaluation related to accumulated other comprehensive loss balance, rate | 0.00% | 0.00% | 0.00%
Other | $ (961) | $ (3,938) | $ (1,456)
Other, rate | (0.30%) | (0.90%) | (0.40%)
Income taxes | $ 84,590 | $ 63,279 | $ 47,485
Total income tax expense, rate | 17.80% | 15.90% | 15.00%

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