Consolidated Statements of Cash Flow(Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Consolidated Statements of Cash Flows
Transfer securities from AFS to HTM, amortized cost	$ 20,228

Transfer securities from AFS to HTM, amortized cost

No definition available.

Name:	dnbf_TransferSecuritiesFromAfsToHtmAmortizedCost
Namespace Prefix:	dnbf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration