Summary of Other Borrowed Funds (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012
Line of Credit Facility [Line Items]
Weighted Average Rate, 2013 (three remaining months)	0.00%	4.12%
2014	1.93%	1.93%
2015	0.00%	1.62%
2018	3.36%	3.36%
2019	2.87%	2.87%
Other borrowings, Weighted Average Rate	7.41%	5.53%
2013		$ 10,000
2014	11,500	11,500
2015		150,000
2018	100,000	100,000
2019	86,000	86,000
Total FHLB advances	197,500	357,500
Credit agreement	317,225	476,103
Credit Agreement
Line of Credit Facility [Line Items]
Other borrowings, Weighted Average Rate	15.00%	15.00%
Credit agreement	116,300	116,300
Repurchase Agreements
Line of Credit Facility [Line Items]
Other borrowings, Weighted Average Rate	0.14%	0.21%
Credit agreement	$ 3,425	$ 2,303