Stockholders' Equity - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Numerator:
Net income available to common shareholders	$ 12,295	$ 21,569
Denominator:
Basic weighted average shares outstanding	16,564,338	16,883,111
Effect of dilutive securities:
SARs and options	151,457	330,075
Restricted stock	83,924	67,259
Diluted weighted average shares outstanding	16,799,719	17,280,445
Basic earnings per share	$ 0.74	$ 1.28
Diluted earnings per share	$ 0.73	$ 1.25