Net Income (Loss) Per Share - Calculations of Net Income (Loss) Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Basic:
Net income (loss)	$ (14,603)	$ 31,319
Weighted average common shares outstanding (in shares)	20,861	21,687
Net income (loss) per share (in dollars per share)	$ (0.70)	$ 1.44
Diluted:
Interest on convertible senior debentures	0	1,051
Net income (loss) attributable to parent, diluted	$ (14,603)	$ 32,370
Number of shares used in basic per share computation (in shares)	20,861	21,687
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	0	3,044
Weighted average common shares outstanding (in shares)	20,861	25,121
Net income (loss) per share (in dollars per share)	$ (0.70)	$ 1.29
Restricted Stock Unit And Performance Stock Unit And Deferred Stock Unit [Member]
Diluted:
Stock options (in shares)	0	23
Employee stock options [Member]
Diluted:
Stock options (in shares)	0	367