Fair Value Measurements and Fair Value of Financial Instruments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Mar. 31, 2013 loan	Jun. 30, 2012 loan	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	$ 363,021	$ 341,263
Allowance for Loan Losses, Ending Balance	6,922	6,177	6,764	5,967	5,617	5,069
Allowance for loan losses	6,922	6,177	6,764	5,967	5,617	5,069
Impaired Financing Receivable, Recorded Investment	7,941	4,707
Impaired Financing Receivable, Related Allowance	1,141	773
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	363,021	341,263
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	6,000	3,100
Allowance for Loan Losses, Ending Balance	1,100	773
Allowance for loan losses	1,100	773
Residential mortgage portfolio [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowance for Loan Losses, Ending Balance	2,490	2,163	2,429	2,098	2,147	1,767
Allowance for loan losses	2,490	2,163	2,429	2,098	2,147	1,767
Fair Value, Number of Loans in Portfolio	12	3
Impaired Financing Receivable, Recorded Investment	3,080	413
Impaired Financing Receivable, Related Allowance	363	10
Nonresidential mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowance for Loan Losses, Ending Balance	2,305	2,076	2,246
Allowance for loan losses	2,305	2,076	2,246
Fair Value, Number of Loans in Portfolio	6	5
Impaired Financing Receivable, Recorded Investment	2,341	1,796
Impaired Financing Receivable, Related Allowance	291	208
Multi-family [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowance for Loan Losses, Ending Balance	265	337	286	353	408	410
Allowance for loan losses	265	337	286	353	408	410
Fair Value, Number of Loans in Portfolio	2	1
Impaired Financing Receivable, Recorded Investment	886	861
Impaired Financing Receivable, Related Allowance	149	155
Commercial construction [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowance for Loan Losses, Ending Balance	415	407	391	480	78	89
Allowance for loan losses	415	407	391	480	78	89
Fair Value, Number of Loans in Portfolio	2	1
Impaired Financing Receivable, Recorded Investment	1,063	1,075
Impaired Financing Receivable, Related Allowance	335	365
Commercial loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowance for Loan Losses, Ending Balance	774	645	727	611	556	528
Allowance for loan losses	774	645	727	611	556	528
Fair Value, Number of Loans in Portfolio	3	1
Impaired Financing Receivable, Recorded Investment	571	562
Impaired Financing Receivable, Related Allowance	$ 3	$ 35