Parent Company Only Condensed Financial Statements - Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2011
ASSETS
Other assets	$ 2,673	$ 2,494
Total assets	701,497	652,962
LIABILITIES AND STOCKHOLDERS' EQUITY
Stockholders' equity	87,159	83,659	87,160	93,516
Total liabilities and stockholders' equity	701,497	652,962
Hampden Bancorp, Inc.
ASSETS
Cash on hand	4,920	967
Short-term investments	0	65
Cash and cash equivalents	4,920	1,032	3,435	7,873
Deferred tax asset	700	1,221
Other assets	4,257	4,305
Total assets	87,159	83,659
LIABILITIES AND STOCKHOLDERS' EQUITY
Stockholders' equity	87,159	83,659
Total liabilities and stockholders' equity	87,159	83,659
Hampden Bancorp, Inc. | Hampden Bank
ASSETS
Investment in common stock of subsidiary	75,289	75,339
Hampden Bancorp, Inc. | Hampden LS, Inc.
ASSETS
Investment in common stock of subsidiary	$ 1,993	$ 1,762