SUBSEQUENT EVENT (Details) (USD $) In Thousands, unless otherwise specified	Mar. 15, 2015
SUBSEQUENT EVENT [Abstract]
Unaudited estimated reduction in actuarial projected benefit obligation	$ 2,300

Unaudited estimated reduction in actuarial projected benefit obligation due to a plan curtailment.

No definition available.

Name:	dcom_UnauditedEstimatedReductionInActuarialProjectedBenefitObligation
Namespace Prefix:	dcom_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant