Net Income (Loss) Per Share - Summary of Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Loss from continuing operations	$ (13,784)	$ (3,480)	$ (44,277)	$ (27,961)
Income from discontinued operations, net of tax (Note 2)	0	129,441	0	140,195
Net income (loss)	$ (13,784)	$ 125,961	$ (44,277)	$ 112,234
Weighted average shares outstanding	28,688	27,544	27,784	27,403
Effect of dilutive stock options	0	0	0	0
Diluted shares outstanding	28,688	27,544	27,784	27,403
Basic loss from continuing operations per share	$ (0.48)	$ (0.13)	$ (1.59)	$ (1.02)
Basic income from discontinued operations per share	0.00	4.70	0.00	5.12
Net income (loss) per share	(0.48)	4.57	(1.59)	4.10
Diluted loss from continuing operations per share	(0.48)	(0.13)	(1.59)	(1.02)
Diluted income from discontinued operations per share	0.00	4.70	0.00	5.12
Net income (loss) per share	(0.48)	4.57	(1.59)	4.10
Cash dividends declared per common share	$ 0.07	$ 0.07	$ 0.21	$ 0.21