Net Income (Loss) Per Share - Calculations of Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Basic:
Net income (loss)	$ (19,022)	$ (7,348)	$ (33,625)	$ 23,971
Weighted average common shares outstanding (in shares)	20,895	20,771	20,878	21,226
Net income (loss) per share (in dollars per share)	$ (0.91)	$ (0.35)	$ (1.61)	$ 1.13
Diluted:
Interest on convertible senior debentures	$ 0	$ 0	$ 0	$ 2,103
Net income (loss) attributable to parent, diluted	$ (19,022)	$ (7,348)	$ (33,625)	$ 26,074
Number of shares used in basic per share computation (in shares)	20,895	20,771	20,878	21,226
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	0	0	0	3,034
Weighted average common shares outstanding (in shares)	20,895	20,771	20,878	24,653
Net income (loss) per share (in dollars per share)	$ (0.91)	$ (0.35)	$ (1.61)	$ 1.06
Restricted Stock Unit And Performance Stock Unit And Deferred Stock Unit [Member]
Diluted:
Stock options (in shares)	0	0	0	22
Employee stock options [Member]
Diluted:
Stock options (in shares)	0	0	0	371