Summary of Significant Accounting Policies - Narrative (Detail) (USD $)	12 Months Ended
	Jun. 30, 2014 Location	Jun. 30, 2013	Jun. 30, 2012
Significant Accounting Policies [Line Items]
Number of office locations (in locations)	10
Mortgage and commercial loans, number of days past due when accrual of interest is discontinued	90 days
Other personal loans, time period past due when loan is charged off	180 days
Period of acceptable repayment after which loans are reclassified to accrual status	6 months
Period during which performance must occur to return troubled debt to accrual status	6 months
Interest and penalties recorded as part of income tax expense	$ 0	$ 0	$ 0
One- to four-family
Significant Accounting Policies [Line Items]
Maximum loan-to-value ratio at time of origination	80.00%
Home equity:
Significant Accounting Policies [Line Items]
Maximum loan-to-value ratio at time of origination	85.00%
Home equity: | Minimum
Significant Accounting Policies [Line Items]
Contractual time period of availability for lines-of-credit to be drawn upon	10 years
Lines-of-credit converted to term loans, amortization period	5 years
Home equity: | Maximum
Significant Accounting Policies [Line Items]
Contractual time period of availability for lines-of-credit to be drawn upon	20 years
Lines-of-credit converted to term loans, amortization period	10 years
Federal Home Loan Bank of Boston
Significant Accounting Policies [Line Items]
Federal Home Loan Bank of Boston stock, par value per share (USD per share)	$ 100
Percentage of residential loans as one of two thresholds for calculating the amount of stock of FHLB the entity is required to acquire and hold	1.00%
Percentage of advances from FHLB as one of two thresholds for calculating the amount of stock of FHLB the entity is required to acquire and hold	5.00%
Hampden Bank
Significant Accounting Policies [Line Items]
Number of subsidiaries owned by Hampden Bank (in entities)	3