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v3.3.1.900

Property, plant and equipment (Details 4) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Property, plant and equipment [Line Items] |  |  |  |
Interest capitalized |  | $ 4,902 | $ 8,586 | $ 6,033
AFUDC - borrowed |  | 4,907 | 3,022 | 2,767
AFUDC - equity |  | 7,971 | 5,803 | 3,322
Property, plant and equipment |  | 6,817,668 | 6,294,778 |
Less accumulated depreciation, depletion and amortization |  | 2,506,571 | 2,386,113 | 2,284,169
Net property, plant and equipment |  | 4,311,097 | 3,908,665 | 3,461,553
Electric: |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment | [1] | 1,786,148 | 1,457,101 | 1,315,822
Natural gas distribution: |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment | [1] | 2,076,581 | 1,904,759 | 1,776,901
Pipeline and midstream: |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | 758,729 | 818,388 | 789,569
Construction materials and contracting: |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | 1,553,428 | 1,529,942 | 1,510,355
Construction services: |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | 163,279 | 144,395 | 134,948
Refining |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | 445,333 | 401,845 | 172,603
Other: |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | 49,537 | 50,937 | $ 49,997
Regulated: | Electric: | Generation |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 1,003,173 | 627,952 |
Weighted average depreciable life in years |  | 39 years |  |
Regulated: | Electric: | Distribution |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 375,612 | 343,692 |
Weighted average depreciable life in years |  | 44 years |  |
Regulated: | Electric: | Transmission |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 255,842 | 229,997 |
Weighted average depreciable life in years |  | 57 years |  |
Regulated: | Electric: | Construction in progress |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 42,436 | 150,445 |
Regulated: | Electric: | Other |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 109,085 | 105,015 |
Weighted average depreciable life in years |  | 14 years |  |
Regulated: | Natural gas distribution: | Distribution |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 1,624,645 | 1,481,390 |
Weighted average depreciable life in years |  | 35 years |  |
Regulated: | Natural gas distribution: | Construction in progress |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 20,530 | 59,310 |
Regulated: | Natural gas distribution: | Other |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 431,406 | 364,059 |
Weighted average depreciable life in years |  | 22 years |  |
Regulated: | Pipeline and midstream: | Transmission |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 460,305 | 449,276 |
Weighted average depreciable life in years |  | 53 years |  |
Regulated: | Pipeline and midstream: | Gathering |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 37,831 | 39,595 |
Weighted average depreciable life in years |  | 20 years |  |
Regulated: | Pipeline and midstream: | Storage |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 44,011 | 43,994 |
Weighted average depreciable life in years |  | 60 years |  |
Regulated: | Pipeline and midstream: | Construction in progress |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 7,549 | 5,386 |
Regulated: | Pipeline and midstream: | Other |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 40,168 | 39,910 |
Weighted average depreciable life in years |  | 33 years |  |
Nonregulated: | Eliminations |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ (15,367) | (12,589) |
Nonregulated: | Pipeline and midstream: | Gathering and processing |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 158,949 | 227,598 |
Weighted average depreciable life in years |  | 16 years |  |
Nonregulated: | Pipeline and midstream: | Construction in progress |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 89 | 691 |
Nonregulated: | Pipeline and midstream: | Other |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 9,827 | 11,938 |
Weighted average depreciable life in years |  | 10 years |  |
Nonregulated: | Construction materials and contracting: | Land |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 123,723 | 125,372 |
Nonregulated: | Construction materials and contracting: | Buildings and improvements |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 69,011 | 70,566 |
Weighted average depreciable life in years |  | 19 years |  |
Nonregulated: | Construction materials and contracting: | Machinery, vehicles and equipment |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 937,084 | 921,564 |
Weighted average depreciable life in years |  | 12 years |  |
Nonregulated: | Construction materials and contracting: | Construction in progress |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 18,615 | 8,709 |
Nonregulated: | Construction materials and contracting: | Aggregate reserves |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment | [2] | 404,995 | 403,731 |
Nonregulated: | Construction services: | Land |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | 6,460 | 5,265 |
Nonregulated: | Construction services: | Buildings and improvements |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 23,824 | 17,936 |
Weighted average depreciable life in years |  | 25 years |  |
Nonregulated: | Construction services: | Machinery, vehicles and equipment |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 121,940 | 112,973 |
Weighted average depreciable life in years |  | 6 years |  |
Nonregulated: | Construction services: | Other |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 11,055 | 8,221 |
Weighted average depreciable life in years |  | 3 years |  |
Nonregulated: | Refining | Construction in progress |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 135 | 313,613 |
Nonregulated: | Refining | Refinery |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 445,198 | 88,232 |
Weighted average depreciable life in years |  | 20 years |  |
Nonregulated: | Other: | Land |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 2,837 | 2,837 |
Nonregulated: | Other: | Other |  |  |  |
Property, plant and equipment [Line Items] |  |  |  |
Property, plant and equipment |  | $ 46,700 | $ 48,100 |
Weighted average depreciable life in years |  | 23 years |  |
[1] | Includes allocations of common utility property
[2] | Depleted on the units-of-production method.

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