Parent Company Only Condensed Financial Statements - Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 4,515	$ 2,974	$ 3,016
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	46	503	926
Deferred tax provision (benefit)	522	(179)	1,296
Net change in:
Other assets	(219)	1,031	(461)
Accrued expenses	(1,437)	539	(893)
Net cash provided by operating activities	6,133	6,740	4,492
Cash flows from investing activities:
Sales	0	3,189	1,308
Maturities	6,626	178	1,000
Net cash provided by investing activities	(63,998)	(43,297)	(46,450)
Cash flows from financing activities:
Common stock repurchased	(454)	(5,271)	(10,410)
Payment of dividends on common stock	(1,268)	(997)	(820)
Net cash used by financing activities	44,914	34,252	38,734
Net increase (decrease) in cash and cash equivalents	(12,951)	(2,305)	(3,224)
Hampden Bancorp, Inc.
Cash flows from operating activities:
Net income	4,515	2,974	3,016
Adjustments to reconcile net income to net cash provided by operating activities:
Dividends in excess of earnings of subsidiaries	5,600	4,500	3,000
Stock-based compensation	46	503	926
Deferred tax provision (benefit)	521	(69)	(30)
Net change in:
Accrued interest receivable	0	0	9
Other assets	(429)	(1,822)	16
Accrued expenses	477	1,508	1,168
Net cash provided by operating activities	5,514	3,475	3,540
Cash flows from investing activities:
Sales	0	15	1,309
Maturities	0	0	1,933
Net cash provided by investing activities	0	15	3,242
Cash flows from financing activities:
Common stock repurchased	(454)	(5,271)	(10,410)
Payment of dividends on common stock	(1,268)	(997)	(820)
Other, net	(656)	(377)	(742)
Net cash used by financing activities	(1,626)	(5,893)	(11,220)
Net increase (decrease) in cash and cash equivalents	3,888	(2,403)	(4,438)
Cash and cash equivalents at beginning of year	1,032	3,435	7,873
Cash and cash equivalents at end of year	4,920	1,032	3,435
Hampden Bancorp, Inc. | Hampden Bank
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed net income of subsidiary	(4,986)	(3,878)	(4,320)
Hampden Bancorp, Inc. | Hampden LS, Inc.
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed net income of subsidiary	(230)	(241)	(245)
Cash flows from financing activities:
Payment of loan from Hampden LS, Inc.	$ 752	$ 752	$ 752