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Income tax expense (benefit) statutory rate versus actual rate (Details 6) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Computed tax at federal statutory rate |  |  |
Computed tax at federal statutory rate | $ 63,104,000 | $ 84,836,000 | $ 85,045,000
Federal statutory rate (in hundredths) | 35.00% | 35.00% | 35.00%
Increases (reductions) resulting from: |  |  |
State income taxes, net of federal income tax | $ 4,903,000 | $ 7,048,000 | $ 7,379,000
State income tax rate (in hundredths) | 2.70% | 2.90% | 3.00%
Noncontrolling interest | $ 12,340,000 | $ 1,363,000 | $ 0
Non-controlling interest (in hundredths) | 6.80% | 0.50% | (0.00%)
Federal renewable energy credit | $ (3,400,000) | $ (3,655,000) | $ (3,404,000)
Federal renewable energy credit rate (in hundreths) | (1.90%) | (1.50%) | (1.40%)
Tax compliance and uncertain tax positions | $ (194,000) | $ (8,987,000) | $ (3,902,000)
Tax compliance and uncertain tax positions (in hundredths) | (0.10%) | (3.70%) | (1.60%)
Domestic production activities | $ 0 | $ (3,993,000) | $ (666,000)
Domestic production activities (in hundredths) | (0.00%) | (1.60%) | (0.30%)
Other | $ (11,150,000) | $ (13,385,000) | $ (10,158,000)
Other rate (in hundredths) | (6.10%) | (5.50%) | (4.10%)
Total income tax expense | $ 65,603,000 | $ 63,227,000 | $ 74,294,000
Total income tax expense (benefit) rate (in hundredths) | 36.40% | 26.10% | 30.60%
Temporary differences [Abstract] |  |  |
Undistributed earnings from foreign operations | $ 2,400,000 |  |
Deferred tax liabilities, undistributed foreign earnings | $ 900,000 |  |

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