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Summary of significant accounting policies (Tables) | 12 Months Ended
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Dec. 31, 2016
Accounting Policies [Abstract] |
Inventories | Inventories at December 31 consisted of:
| 2016 |  | 2015 |
| (In thousands)
Aggregates held for resale | $ | 115,471 |  | $ | 115,854 |
Asphalt oil | 29,103 |  | 36,498 |
Natural gas in storage (current) | 25,761 |  | 21,023 |
Materials and supplies | 18,372 |  | 16,997 |
Merchandise for resale | 16,437 |  | 15,318 |
Other | 33,129 |  | 34,861 |
Total | $ | 238,273 |  | $ | 240,551 |
AFUDC and interest capitailized | The amount of AFUDC and interest capitalized for the years ended December 31 were as follows:
| 2016 |  | 2015 |  | 2014 |
|  | (In thousands) |  |
Interest capitalized | $ | — |  | $ | 4,381 |  | $ | 7,046 |
AFUDC - borrowed | $ | 914 |  | $ | 4,907 |  | $ | 3,023 |
AFUDC - equity | $ | 565 |  | $ | 7,971 |  | $ | 5,803 |
Property, plant and equipment | Property, plant and equipment at December 31 was as follows:
| 2016 |  | 2015 |  | Weighted Average Depreciable Life in Years
| (Dollars in thousands, where applicable)
Regulated: |  |  |
Electric: |  |  |
Generation | $ | 1,036,373 |  | $ | 1,003,173 |  | 39
Distribution | 398,382 |  | 375,612 |  | 44
Transmission | 284,048 |  | 255,842 |  | 57
Construction in progress | 62,212 |  | 42,436 |  | -
Other | 107,598 |  | 109,085 |  | 14
Natural gas distribution: |  |  |
Distribution | 1,718,633 |  | 1,624,645 |  | 46
Construction in progress | 19,934 |  | 20,530 |  | -
Other | 440,846 |  | 431,406 |  | 18
Pipeline and midstream: |  |  |
Transmission | 490,143 |  | 460,305 |  | 54
Gathering | 37,831 |  | 37,831 |  | 20
Storage | 45,350 |  | 44,011 |  | 62
Construction in progress | 16,507 |  | 7,549 |  | -
Other | 40,873 |  | 40,168 |  | 33
Nonregulated: |  |  |
Pipeline and midstream: |  |  |
Gathering and processing | 31,682 |  | 158,949 |  | 19
Construction in progress | 13 |  | 89 |  | -
Other | 9,800 |  | 9,827 |  | 10
Construction materials and contracting: |  |  |
Land | 94,625 |  | 95,870 |  | -
Buildings and improvements | 102,347 |  | 96,864 |  | 19
Machinery, vehicles and equipment | 930,471 |  | 937,084 |  | 12
Construction in progress | 16,181 |  | 18,615 |  | -
Aggregate reserves | 405,751 |  | 404,995 |  | *
Construction services: |  |  |
Land | 5,346 |  | 5,025 |  | -
Buildings and improvements | 26,693 |  | 25,259 |  | 26
Machinery, vehicles and equipment | 132,217 |  | 121,940 |  | 6
Other | 7,105 |  | 11,055 |  | 4
Other: |  |  |
Land | 2,837 |  | 2,837 |  | -
Other | 46,431 |  | 46,700 |  | 23
Less accumulated depreciation, depletion and amortization | 2,578,902 |  | 2,489,322 |  |
Net property, plant and equipment | $ | 3,931,327 |  | $ | 3,898,380 |  |
* | Depleted on the units-of-production method based on recoverable aggregate reserves.
Percentage-of-completion method | Costs and estimated earnings in excess of billings and billings in excess of costs and estimated earnings on uncompleted contracts at December 31 were as follows:
| 2016 |  | 2015 |
| (In thousands)
Costs and estimated earnings in excess of billings on uncompleted contracts | $ | 64,558 |  | $ | 64,369 |
Billings in excess of costs and estimated earnings on uncompleted contracts | $ | 64,832 |  | $ | 68,048 |
Amounts representing balances billed but not paid by customers under retainage provisions in contracts at December 31 were as follows:
| 2016 |  | 2015 |
| (In thousands)
Short-term retainage* | $ | 45,109 |  | $ | 46,207 |
Long-term retainage** | 1,506 |  | 1,605 |
Total retainage | $ | 46,615 |  | $ | 47,812 |
* | Expected to be paid within one year or less and included in receivables, net.
** | Included in deferred charges and other assets - other.
Schedule of earnings per share reconciliation | A reconciliation of the weighted average common shares outstanding used in the basic and diluted earnings (loss) per share calculation was as follows:
| 2016 |  | 2015 |  | 2014 |
|  | (In thousands) |  |
Weighted average common shares outstanding - basic | 195,299 |  | 194,928 |  | 192,507 |
Effect of dilutive performance share awards | 319 |  | 58 |  | 80 |
Weighted average common shares outstanding - diluted | 195,618 |  | 194,986 |  | 192,587 |
Shares excluded from the calculation of diluted earnings per share | — |  | — |  | — |
After-tax changes in the components of accumulated other comprehensive income (loss) | The after-tax changes in the components of accumulated other comprehensive loss as of December 31, 2016, 2015 and 2014, were as follows:
| Net Unrealized Gain (Loss) on Derivative Instruments Qualifying as Hedges |  | Post- retirement Liability Adjustment |  | Foreign Currency Translation Adjustment |  | Net Unrealized Gain (Loss) on Available- for-sale Investments |  | Total Accumulated Other Comprehensive Loss |
|  |  | (In thousands) |  |  |
Balance at December 31, 2014 | $ | (3,071 | ) | $ | (38,218 | ) | $ | (829 | ) | $ | 15 |  | $ | (42,103 | )
Other comprehensive income (loss) before reclassifications | — |  | (88 | ) | (173 | ) | (170 | ) | (431 | )
Amounts reclassified from accumulated other comprehensive loss | 404 |  | 1,794 |  | 802 |  | 131 |  | 3,131 |
Amounts reclassified from accumulated other comprehensive loss to a regulatory asset | — |  | 2,255 |  | — |  | — |  | 2,255 |
Net current-period other comprehensive income (loss) | 404 |  | 3,961 |  | 629 |  | (39 | ) | 4,955 |
Balance at December 31, 2015 | (2,667 | ) | (34,257 | ) | (200 | ) | (24 | ) | (37,148 | )
Other comprehensive income (loss) before reclassifications | — |  | (1,470 | ) | 51 |  | (182 | ) | (1,601 | )
Amounts reclassified from accumulated other comprehensive loss | 367 |  | 2,506 |  | — |  | 143 |  | 3,016 |
Net current-period other comprehensive income (loss) | 367 |  | 1,036 |  | 51 |  | (39 | ) | 1,415 |
Balance at December 31, 2016 | $ | (2,300 | ) | $ | (33,221 | ) | $ | (149 | ) | $ | (63 | ) | $ | (35,733 | )
Reclassification out of accumulated other comprehensive income (loss) | Reclassifications out of accumulated other comprehensive loss for the years ended December 31 were as follows:
| 2016 |  | 2015 |  | Location on Consolidated Statements of Income
| (In thousands) |
Reclassification adjustment for loss on derivative instruments included in net income (loss): |  |  |
Interest rate derivative instruments | $ | (593 | ) | $ | (637 | ) | Interest expense
| 226 |  | 233 |  | Income taxes
| (367 | ) | (404 | ) |
Amortization of postretirement liability losses included in net periodic benefit cost (credit) | (3,931 | ) | (2,922 | ) | (a)
| 1,425 |  | 1,128 |  | Income taxes
| (2,506 | ) | (1,794 | ) |
Reclassification adjustment for loss on foreign currency translation adjustment included in net income (loss) | — |  | (1,292 | ) | Other income
| — |  | 490 |  | Income taxes
| — |  | (802 | ) |
Reclassification adjustment for loss on available-for-sale investments included in net income (loss) | (220 | ) | (201 | ) | Other income
| 77 |  | 70 |  | Income taxes
| (143 | ) | (131 | ) |
Total reclassifications | $ | (3,016 | ) | $ | (3,131 | ) |
(a) | Included in net periodic benefit cost (credit). For more information, see Note 14.

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