Earnings and Dividends per Share - Computational Components of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Basic net income and earnings per share, Numerator (Income)	$ 4,493	$ 3,043	$ 7,514	$ 5,251
Common stock equivalents arising from stock options and employee stock purchase plan, Numerator (Income)	0		0
Diluted earnings and earnings per share, Numerator (Income)	$ 4,493	$ 3,043	$ 7,514	$ 5,251
Basic net income and earnings per share, Denominator (Shares)	25,643,508	17,750,512	25,625,033	17,416,118
Common stock equivalents arising from stock options and employee stock purchase plan, Denominator (Shares)	464,000	604,000	487,000	651,000
Diluted earnings and earnings per share, Denominator (Shares)	26,107,648	18,355,496	26,111,683	18,066,539
Basic net income and earnings per share, Per Share Amount	$ 0.18	$ 0.17	$ 0.29	$ 0.30
Common stock equivalents arising from stock options and employee stock purchase plan, Per share amount	$ (0.01)		$ 0.00	$ (0.01)
Diluted earnings and earnings per share, Per Share Amount	$ 0.17	$ 0.17	$ 0.29	$ 0.29