Other Borrowed Funds - Additional Information (Detail) (USD $)	1 Months Ended											9 Months Ended			12 Months Ended
	Dec. 21, 2012	Mar. 31, 2013		Mar. 31, 2012		Dec. 31, 2009	Sep. 30, 2009	Mar. 31, 2013 Minimum	Mar. 31, 2013 Maximum	Mar. 31, 2013 Line of Credit	Mar. 31, 2012 Line of Credit	Dec. 31, 2012 Bonds	Mar. 31, 2013 Federal Home Loan Bank Advances	Mar. 31, 2012 Federal Home Loan Bank Advances	Mar. 31, 2013 Federal Home Loan Bank Advances Mortgage Related Securities	Mar. 31, 2012 Federal Home Loan Bank Advances Mortgage Related Securities	Mar. 31, 2013 Federal Home Loan Bank Advances Call Features	Mar. 31, 2013 Credit Agreement	Mar. 31, 2012 Credit Agreement
Borrowings [Line Items]
Fair value of FHLB borrowings collateralized by mortgage-related securities															$ 152,100,000	$ 184,600,000	$ 181,000,000
Unpaid principal balance of pledged secure FHLB borrowings													717,000,000	744,600,000
Prepaid FHLB advances	150,000,000
Prepaid FHLB advances, interest type	Floating
Prepaid FHLB advances, maturity date	2015-01
Prepaid FHLB advances current weighted average rate	1.41%
Prepaid FHLB advances, early termination penalty	3,500,000
Short term line of credit to various lenders led by U.S. Bank		317,225,000		476,103,000						116,300,000	116,300,000							116,300,000	116,300,000
Weighted average rate on a short term line of credit		7.41%		5.53%						15.00%	15.00%							15.00%	15.00%
Total line of credit		116,300,000
Accrued interest																		53,300,000
Amendment fees payable																		6,900,000
Tier 1 leverage ratio of not less than		4.53%						4.00%
Total risk-based capital ratio		10.00%	[1]	10.00%	[1]	12.00%	11.00%	8.00%
Ratio of non-performing loans to gross loans not to exceed									13.00%
Issuance of bonds												$ 60,000,000
Interest at a fixed rate												2.74%
Maturity date of bonds												Feb. 11, 2012
Bonds issued under program and subsequent												Dec. 05, 2008

[1] Total risk-based capital divided by total risk-weighted assets.