Stockholders' Equity - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Numerator:
Net income (loss)	$ 15,103	$ (15,298)	$ 13,224	$ 21,569	$ (3,619)	$ (14,312)	$ 8,339	$ 12,311	$ 34,598	$ 2,720	$ (11,588)
Denominator:
Basic weighted average shares outstanding									16,794,841	16,123,592	15,388,456
Effect of dilutive securities:
SARS and options									255,353	406,482
Restricted stock									86,557	51,799
Convertible notes										482,983
Diluted weighted average shares outstanding									17,136,751	17,064,856	15,388,456
Basic earnings (loss) per share	$ 0.91	$ (0.91)	$ 0.78	$ 1.28	$ (0.22)	$ (0.86)	$ 0.54	$ 0.80	$ 2.06	$ 0.17	$ (0.75)
Diluted earnings (loss) per share	$ 0.90	$ (0.91)	$ 0.76	$ 1.25	$ (0.22)	$ (0.86)	$ 0.48	$ 0.74	$ 2.02	$ 0.16	$ (0.75)