Annual report pursuant to Section 13 and 15(d)

Earnings (Loss) Per Share (EPS) - Summary of Reconciliation of Income and Number of Shares Used to Calculate Basic and Diluted Earnings per Share (EPS) (Detail)

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Earnings (Loss) Per Share (EPS) - Summary of Reconciliation of Income and Number of Shares Used to Calculate Basic and Diluted Earnings per Share (EPS) (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Earnings Per Share [Abstract]                      
Basic earnings (loss) per common share $ (29,599) $ (21,217) $ (31,127) $ (39,809) $ (48,929) $ (46,228) $ (39,822) $ (95,835) $ (121,752) $ (230,814) $ (95,073)
Diluted earnings (loss) per common share                 $ (121,752) $ (230,814) $ (95,073)
Basic earnings (loss) per common share (in shares)                 136,266,843 124,130,004 122,562,187
Diluted earnings (loss) per common share                 136,266,843 124,130,004 122,562,187
Basic earnings (loss) per common share (in dollars per share) $ (0.21) $ (0.15) $ (0.23) $ (0.31) $ (0.39) $ (0.37) $ (0.32) $ (0.78) $ (0.89) $ (1.86) $ (0.78)
Restricted stock units (in shares)                 0 0 0
Restricted stock units (in dollars per share) 0.00       0.00       $ 0.00 $ 0.00 $ 0.00
Diluted earnings (loss) per common share (in dollars per share) $ (0.21) $ (0.15) $ (0.23) $ (0.31) $ (0.39) $ (0.37) $ (0.32) $ (0.78) $ (0.89) $ (1.86) $ (0.78)
Shares excluded from the computation of diluted EPS                 23,809,500