Earnings Per Share - Summary of Calculation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Numerator
Net income	$ 9,607	$ 7,890
Denominator
Weighted average number of shares - basic	56,751	61,847
Effect of dilutive securities
Stock options	602	162
Restricted stock and restricted stock units	15	21
Weighted average number of shares - diluted	57,368	62,030
Net income per share - basic	$ 0.17	$ 0.13
Net income per share - diluted	$ 0.17	$ 0.13