Loan Receivable and Allowance for Loan and Lease Losses Impaired loans with an allowance recorded (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Mar. 31, 2012
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	$ 619	$ 1,142
Impaired Financing Receivable, Recorded Investment	25,780		36,247
Impaired Financing Receivable, Unpaid Principal Balance	27,745		39,309
Impaired Financing Receivable, Related Allowance	2,281		949
Impaired Financing Receivable, Average Recorded Investment	29,252	56,430
Multifamily Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	0	70
Impaired Financing Receivable, Recorded Investment	678		814
Impaired Financing Receivable, Unpaid Principal Balance	871		879
Impaired Financing Receivable, Related Allowance	49		61
Impaired Financing Receivable, Average Recorded Investment	742	8,010
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	115	99
Impaired Financing Receivable, Recorded Investment	6,225		14,469
Impaired Financing Receivable, Unpaid Principal Balance	6,772		15,068
Impaired Financing Receivable, Related Allowance	435		532
Impaired Financing Receivable, Average Recorded Investment	8,182	8,622
Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, Recorded Investment	0		681
Impaired Financing Receivable, Unpaid Principal Balance	0		1,613
Impaired Financing Receivable, Related Allowance	0		48
Impaired Financing Receivable, Average Recorded Investment	0	4,497
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	199	71
Impaired Financing Receivable, Recorded Investment	4,616		1,089
Impaired Financing Receivable, Unpaid Principal Balance	4,616		1,776
Impaired Financing Receivable, Related Allowance	1,670		101
Impaired Financing Receivable, Average Recorded Investment	3,242	1,607
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method		0
Impaired Financing Receivable, Recorded Investment			0
Impaired Financing Receivable, Unpaid Principal Balance			0
Impaired Financing Receivable, Related Allowance			0
Impaired Financing Receivable, Average Recorded Investment	0
One- to four family loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	28	61
Impaired Financing Receivable, Recorded Investment	2,718		1,679
Impaired Financing Receivable, Unpaid Principal Balance	2,800		1,760
Impaired Financing Receivable, Related Allowance	127		207
Impaired Financing Receivable, Average Recorded Investment	2,552	7,624
Impaired Financing Receivable with Related Allowance [Domain]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	342	301
Impaired Financing Receivable, Recorded Investment	14,237		18,732
Impaired Financing Receivable, Unpaid Principal Balance	15,059		21,096
Impaired Financing Receivable, Related Allowance	2,281		949
Impaired Financing Receivable, Average Recorded Investment	14,718	30,360
Class of Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	277	841
Impaired Financing Receivable, Recorded Investment	11,543		17,515
Impaired Financing Receivable, Unpaid Principal Balance	12,686		18,213
Impaired Financing Receivable, Related Allowance	0
Impaired Financing Receivable, Average Recorded Investment	14,534	26,070
One- to four family loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	27	36
Impaired Financing Receivable, Recorded Investment	206		628
Impaired Financing Receivable, Unpaid Principal Balance	1,080		628
Impaired Financing Receivable, Related Allowance	0		0
Impaired Financing Receivable, Average Recorded Investment	467	2,173
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method		0
Impaired Financing Receivable, Recorded Investment	0		0
Impaired Financing Receivable, Unpaid Principal Balance	0		0
Impaired Financing Receivable, Related Allowance	0		0
Impaired Financing Receivable, Average Recorded Investment	0	0
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	41	106
Impaired Financing Receivable, Recorded Investment	936		4,983
Impaired Financing Receivable, Unpaid Principal Balance	936		5,417
Impaired Financing Receivable, Related Allowance	0		0
Impaired Financing Receivable, Average Recorded Investment	2,536	2,435
Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	53	680
Impaired Financing Receivable, Recorded Investment	4,258		5,406
Impaired Financing Receivable, Unpaid Principal Balance	4,527		5,670
Impaired Financing Receivable, Related Allowance	0		0
Impaired Financing Receivable, Average Recorded Investment	5,293	17,307
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	151	4
Impaired Financing Receivable, Recorded Investment	6,143		6,304
Impaired Financing Receivable, Unpaid Principal Balance	6,143		6,304
Impaired Financing Receivable, Related Allowance	0		0
Impaired Financing Receivable, Average Recorded Investment	6,141	3,958
Multifamily Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	5	15
Impaired Financing Receivable, Recorded Investment	0		194
Impaired Financing Receivable, Unpaid Principal Balance	0		194
Impaired Financing Receivable, Related Allowance	0		0
Impaired Financing Receivable, Average Recorded Investment	97	197
Multifamily Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	5	85
Impaired Financing Receivable, Recorded Investment	678		1,008
Impaired Financing Receivable, Unpaid Principal Balance	871		1,073
Impaired Financing Receivable, Related Allowance	49		61
Impaired Financing Receivable, Average Recorded Investment	839	8,207
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	266	103
Impaired Financing Receivable, Recorded Investment	12,368		20,773
Impaired Financing Receivable, Unpaid Principal Balance	12,915		21,372
Impaired Financing Receivable, Related Allowance	435		532
Impaired Financing Receivable, Average Recorded Investment	14,323	12,580
Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	53	680
Impaired Financing Receivable, Recorded Investment	4,258		6,087
Impaired Financing Receivable, Unpaid Principal Balance	4,527		7,283
Impaired Financing Receivable, Related Allowance	0		48
Impaired Financing Receivable, Average Recorded Investment	5,293	21,804
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	240	177
Impaired Financing Receivable, Recorded Investment	5,552		6,072
Impaired Financing Receivable, Unpaid Principal Balance	5,552		7,193
Impaired Financing Receivable, Related Allowance	1,670		101
Impaired Financing Receivable, Average Recorded Investment	5,778	4,042
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	0	0
Impaired Financing Receivable, Recorded Investment	0		0
Impaired Financing Receivable, Unpaid Principal Balance	0		0
Impaired Financing Receivable, Related Allowance	0		0
Impaired Financing Receivable, Average Recorded Investment	0	0
One- to four family loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	55	97
Impaired Financing Receivable, Recorded Investment	2,924		2,307
Impaired Financing Receivable, Unpaid Principal Balance	3,880		2,388
Impaired Financing Receivable, Related Allowance	127		207
Impaired Financing Receivable, Average Recorded Investment	$ 3,019	$ 9,797