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Income tax expense (benefit) statutory rate versus actual rate (Details 7) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Computed tax at federal statutory rate |  |  |  |
Computed tax at federal statutory rate |  | $ 83,674 | $ 66,543 | $ 122,509
Federal statutory rate |  | 21.00% | 21.00% | 35.00%
Increases (reductions) resulting from: |  |  |  |
State income taxes, net of federal income tax |  | $ 14,029 | $ 12,190 | $ 10,724
State income tax, rate |  | 3.50% | 3.80% | 3.10%
Federal renewable energy credit |  | $ (15,843) | $ (11,759) | $ (13,958)
Federal renewable energy credit, rate |  | (4.00%) | (3.70%) | (4.00%)
Tax compliance and uncertain tax positions |  | $ (2,739) | $ (2,725) | $ (643)
Tax compliance and uncertain tax positions, rate |  | (0.70%) | (0.90%) | (0.20%)
Domestic production deduction |  | $ 0 | $ 0 | $ (6,849)
Domestic production deduction, rate |  | 0.00% | 0.00% | (2.00%)
Excess deferred income tax amortization |  | $ (11,904) | $ (9,319) | $ (397)
Excess deferred income tax amortization, rate |  | (3.00%) | (2.90%) | 0.00%
TCJA revaluation |  | $ 0 | $ (5,947) | $ (47,242)
TCJA revaluation, rate |  | 0.00% | (1.90%) | (13.50%)
TCJA revaluation related to accumulated other comprehensive loss balance | $ 39,500 | $ 0 | $ (42) | $ 7,735
TCJA revaluation related to accumulated other comprehensive loss balance, rate |  | 0.00% | 0.00% | 2.20%
Other |  | $ (3,938) | $ (1,456) | $ (6,838)
Other, rate |  | (0.90%) | (0.40%) | (2.00%)
Income taxes |  | $ 63,279 | $ 47,485 | $ 65,041
Total income tax expense, rate |  | 15.90% | 15.00% | 18.60%

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