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v3.3.1.900

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Jun. 30, 2013 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Operating revenues | $ 1,062,485 | $ 1,280,500 | $ 986,215 | $ 862,349 | $ 1,048,288 | $ 1,213,203 | $ 952,564 | $ 900,761 |  | $ 4,191,549 | $ 4,114,816 | $ 3,920,171
Operating expenses | 1,007,092 | 1,170,757 | 940,887 | 818,680 | 973,720 | 1,094,310 | 890,210 | 837,153 |  | 3,937,416 | 3,795,393 | 3,599,469
Operating income | 55,393 | 109,743 | 45,328 | 43,669 | 74,568 | 118,893 | 62,354 | 63,608 |  | 254,133 | 319,423 | 320,702
Income from continuing operations | 32,077 | 53,400 | 14,057 | 15,160 | 55,051 | 63,639 | 29,446 | 31,027 |  | 114,694 | 179,163 | 168,691
Income (loss) from discontinued operations, net of tax | 6,261 | (202,626) | (251,415) | (324,605) | 27,700 | 38,482 | 23,881 | 25,112 |  | $ (772,385) | $ 115,175 | $ 109,879
Net income (loss) attributable to parent | $ 52,534 | $ (139,448) | $ (229,604) | $ (305,917) | $ 84,256 | $ 103,209 | $ 54,106 | $ 56,662 |  |  |  |
Earnings (loss) per common share - basic [Abstract] |  |  |  |  |  |  |  |  |  |  |  |
Earnings before discontinued operations | $ 0.24 | $ 0.32 | $ 0.11 | $ 0.10 | $ 0.29 | $ 0.33 | $ 0.16 | $ 0.17 |  | $ 0.77 | $ 0.95 | $ 0.89
Discontinued operations, net of tax | 0.03 | (1.04) | (1.29) | (1.67) | 0.14 | 0.20 | 0.12 | 0.13 |  | (3.97) | 0.60 | 0.58
Earnings (loss) per common share - basic | $ 0.27 | $ (0.72) | $ (1.18) | $ (1.57) | $ 0.43 | $ 0.53 | $ 0.28 | $ 0.30 |  | $ (3.20) | $ 1.55 | $ 1.47
Weighted average common shares outstanding - basic | 195,266 | 195,151 | 194,805 | 194,479 | 194,136 | 193,949 | 192,060 | 189,820 |  | 194,928 | 192,507 | 188,855
Earnings per common share - diluted [Abstract] |  |  |  |  |  |  |  |  |  |  |  |
Earnings before discontinued operations | $ 0.24 | $ 0.32 | $ 0.11 | $ 0.10 | $ 0.29 | $ 0.33 | $ 0.16 | $ 0.16 |  | $ 0.77 | $ 0.95 | $ 0.89
Discontinued operations, net of tax | 0.03 | (1.04) | (1.29) | (1.67) | 0.14 | 0.20 | 0.12 | 0.14 |  | (3.97) | 0.60 | 0.58
Earnings (loss) per common share - diluted | $ 0.27 | $ (0.72) | $ (1.18) | $ (1.57) | $ 0.43 | $ 0.53 | $ 0.28 | $ 0.30 |  | $ (3.20) | $ 1.55 | $ 1.47
Weighted average common shares outstanding - diluted | 195,324 | 195,169 | 194,838 | 194,566 | 194,219 | 194,300 | 192,659 | 190,432 |  | 194,986 | 192,587 | 189,693
Additional Information [Abstract] |  |  |  |  |  |  |  |  |  |  |  |
Asset impairment charges |  | $ 14,100 | $ 3,000 |  |  |  |  |  | $ 14,500 |  |  |
Withdrawal from multiemployer defined benefit plan [Member] | Operating Engineers Local 800 and WY Contractors Association Pension Plan for WY [Member] |  |  |  |  |  |  |  |  |  |  |  |
Additional Information [Abstract] |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer plan withdrawal obligation |  |  |  | $ 2,400 | $ 14,000 |  |  |  |  |  |  |

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