Earnings Per Share - Reconciliation of Basic and Diluted Net Income Per Share Attributable to Common Stockholders (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Net income per share:
Net Income	$ 5,128	$ 2,769	$ 5,220	$ 2,172	$ 3,865	$ 1,422	$ 3,764	$ 2,201	$ 15,289	$ 11,252	$ 10,036
Preferred Stock Dividends, Income Statement Impact									0	0	13,141
Other Preferred Stock Dividends and Adjustments									0	0	(3,408)
Net income attributable to common stockholders									$ 15,289	$ 11,252	$ 303
Weighted average shares of common stock outstanding used in computing net income-basic	17,005,472	16,937,139	16,896,227	16,869,557	17,262,253	17,249,536	17,070,327	16,936,007	16,926,827	17,129,334	469,089
Weighted average shares of common stock outstanding used in computing net income-diluted	17,425,573	17,398,006	17,392,447	17,353,222	17,724,131	17,781,720	17,702,516	17,600,908	17,412,548	17,707,839	1,111,088
Earnings per share
-Basic (in dollars per share)	$ 0.30	$ 0.16	$ 0.31	$ 0.13	$ 0.22	$ 0.08	$ 0.22	$ 0.13	$ 0.90	$ 0.66	$ 0.65
-Diluted (in dollars per share)	$ 0.29	$ 0.16	$ 0.30	$ 0.13	$ 0.22	$ 0.08	$ 0.21	$ 0.12	$ 0.88	$ 0.64	$ 0.27
Stock Options
Net income per share:
Potential dilutive									467,146	570,210	641,999
Restricted Stock Units
Net income per share:
Potential dilutive									18,575	8,295	0