NATURE OF OPERATIONS (Details)	9 Months Ended
Sep. 30, 2016 RetailBranch
NATURE OF OPERATIONS [Abstract]
Number of retail banking offices	25

The number of full service retail banking offices at period end.

No definition available.

Name:	dcom_NumberOfRetailOffices
Namespace Prefix:	dcom_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration