TREASURY STOCK (Details) (USD $)	Apr. 30, 2013	May 01, 2012	Apr. 30, 2012
TREASURY STOCK [Abstract]
Treasury stock issued attributable to restricted stock award grant (in shares)	145,925		141,289
Closing price of company stock (in dollars per share)	$ 14.27	$ 13.55	$ 13.86
Issuance of Treasury Stock for BMP award	15,049	10,729

Number of treasury shares (units) issued during the period used to satisfy a grant of restricted stock awards.

No definition available.

Name:	dcom_TreasuryStockIssuedAttributableToShareBasedPaymentArrangements
Namespace Prefix:	dcom_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant