Quarterly Financial Data (Unaudited) - Quarterly Financial Data (Detail) - USD ($)
$ / shares in Units, $ 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
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]                      
Contract revenue $ 217,660 $ 222,191 $ 218,789 $ 250,354 $ 344,953 $ 448,134 $ 423,154 $ 378,129 $ 908,994 $ 1,594,370 $ 1,495,125
Contract income 7,990 13,336 11,578 7,850 18,612 38,631 21,448 18,061 40,754 96,752  
Operating income (loss) (5,408) (12,367) (13,038) (21,285) (15,437) 3,175 (6,307) (9,878) (52,098) (28,447) 2,836
Income (loss) from continuing operations before income taxes (13,658) (19,454) (19,920) (65,548) (37,282) (4,643) (14,889) (17,565) (118,580) (74,379) (40,690)
Loss from continuing operations 19,209 (19,411) (19,403) (44,944) (42,439) 15,305 (5,058) (42,416) (64,549) (74,608) (36,698)
Income (loss) from discontinued operations, net of provision for income taxes 58,183 2,212 517 35,120 6,472 (18,664) (10,453) 17,426 96,032 (5,219) 20,831
Net loss $ 77,392 $ (17,199) $ (18,886) $ (9,824) $ (35,967) $ (3,359) $ (15,511) $ (24,990) $ 31,483 $ (79,827) $ (15,867)
Basic income (loss) per share attributable to Company shareholders:                      
Loss from continuing operations (in dollar per share) $ 0.32 $ (0.32) $ (0.33) $ (0.90) $ (0.86) $ 0.31 $ (0.11) $ (0.87) $ (1.12) $ (1.51) $ (0.76)
Income (loss) from discontinued operations (in dollar per share) 0.96 0.03 0.01 0.70 0.14 (0.38) (0.21) 0.36 1.66 (0.11) 0.44
Net income (loss) (in dollar per share) 1.28 (0.29) (0.32) (0.20) (0.72) (0.07) (0.32) (0.51) 0.54 (1.62) (0.32)
Diluted income (loss) per share attributable to Company shareholders:                      
Loss from continuing operations (in dollar per share) 0.31 (0.32) (0.33) (0.90) (0.86) 0.30 (0.11) (0.87) (1.12) (1.51) (0.76)
Income (loss) from discontinued operations (in dollar per share) 0.95 0.03 0.01 0.70 0.14 (0.37) (0.21) 0.36 1.66 (0.11) 0.44
Net income (loss) (in dollar per share) $ 1.26 $ (0.29) $ (0.32) $ (0.20) $ (0.72) $ (0.07) $ (0.32) $ (0.51) $ 0.54 $ (1.62) $ (0.32)
Weighted average number of common shares outstanding                      
Basic (in shares) 60,510,199 60,335,717 60,227,495 49,819,388 49,630,085 49,414,847 49,336,581 48,847,349 57,759,988 49,310,044 48,560,167
Diluted (in shares) 61,091,783 60,335,717 60,227,495 49,819,388 49,630,085 50,226,661 49,336,581 48,847,349 57,759,988 49,310,044 48,560,167