Net Income (Loss) Per Share - Potentially Dilutive Securities Not Included in Computation of Diluted Net Loss Per Share (Detail) - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
DSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Units, potentially dilutive securities not included in the computation of diluted net loss per share (in shares)	17	39	17	39
Weighted Average Price per Share, anti-dilutive securities excluded from computation of earnings per share (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00
SARs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Units, potentially dilutive securities not included in the computation of diluted net loss per share (in shares)	307	483	307	483
Weighted Average Price per Share, anti-dilutive securities excluded from computation of earnings per share (in dollars per share)	$ 11.28	$ 10.62	$ 11.28	$ 10.62
Restricted stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Units, potentially dilutive securities not included in the computation of diluted net loss per share (in shares)	2,101	2,676	2,101	2,676
Weighted Average Price per Share, anti-dilutive securities excluded from computation of earnings per share (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00