v3.6.0.2

Quarterly Financial Data - Summary of Condensed Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract] |  |  |  |  |  |  |  |  |  |  |
Operating revenues, net | $ 144,853 | $ 158,093 | $ 167,136 | $ 164,016 | $ 186,751 | $ 214,733 | $ 198,547 | $ 204,197 | $ 634,098 | $ 804,228 | $ 836,270
(Loss) gain on disposition of assets, net | (504) | (85) | 4,298 | (359) | (577) | 165 | 66 | 7 | 3,350 | (339) | (848)
(Loss) earnings before income taxes | (12,012) | (7,766) | 117 | (7,488) | 938 | 14,290 | 11,044 | 16,984 | (27,149) | 43,256 | 53,115
Net (loss) earnings | (17,058) | (4,967) | 4,277 | (8,932) | 2,438 | 7,669 | 6,454 | 10,363 | (26,680) | 26,924 | 32,688
Net (loss) earnings per share |  |  |  |  |  |  |  |  |  |  |
Operating revenues, net | 144,853 | 158,093 | 167,136 | 164,016 | 186,751 | 214,733 | 198,547 | 204,197 | 634,098 | 804,228 | 836,270
Gain (loss) on disposition of assets, net | (504) | (85) | 4,298 | (359) | (577) | 165 | 66 | 7 | 3,350 | (339) | (848)
Earnings before income taxes | (12,012) | (7,766) | 117 | (7,488) | 938 | 14,290 | 11,044 | 16,984 | (27,149) | 43,256 | 53,115
Net earnings | $ (17,058) | $ (4,967) | $ 4,277 | $ (8,932) | $ 2,438 | $ 7,669 | $ 6,454 | $ 10,363 | $ (26,680) | $ 26,924 | $ 32,688
Basic | $ (1.08) | $ (0.32) | $ 0.27 | $ (0.57) | $ 0.16 | $ 0.49 | $ 0.41 | $ 0.67 |  |  |
Diluted | $ (1.08) | $ (0.32) | $ 0.27 | $ (0.57) | $ 0.16 | $ 0.49 | $ 0.41 | $ 0.66 |  |  |

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