Note 5 - Loans and Allowance for Credit Losses (Details) - Impaired Loans (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	$ 35,527	$ 45,512	$ 37,420
Recorded Investment With No Allowance	19,773	17,272	20,454
Recorded Investment With Allowance	13,238	26,992	15,491
Total Recorded Investment	33,011	44,264	35,945
Related Allowance	7,583	7,888	8,064
Commercial Loan [Member] \| Year to Date [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	12,116	12,213	13,681
Interest Income Recognized			251
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	13,080	17,646	14,075
Recorded Investment With No Allowance	1,464	6,409	1,603
Recorded Investment With Allowance	9,793	11,237	11,372
Total Recorded Investment	11,257	17,646	12,975
Related Allowance	5,771	3,810	5,334
Commercial Real Estate Investment [Member] \| Year to Date [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	10,235	5,771	7,021
Interest Income Recognized	35	35	203
Commercial Real Estate Investment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	10,668	6,016	10,869
Recorded Investment With No Allowance	8,753	1,106	8,952
Recorded Investment With Allowance	1,222	4,535	1,542
Total Recorded Investment	9,975	5,641	10,494
Related Allowance	568	732	751
Commercial Real Estate Owner Occupied [Member] \| Year to Date [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,878	6,388	3,986
Interest Income Recognized			6
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	1,867	7,323	1,889
Recorded Investment With No Allowance	1,025	4,191	1,038
Recorded Investment With Allowance	842	3,132	851
Total Recorded Investment	1,867	7,323	1,889
Related Allowance	400	1,105	577
Residential Mortgage [Member] \| Year to Date [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	344	829	529
Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	342	771	346
Recorded Investment With No Allowance	342	658	346
Recorded Investment With Allowance		113
Total Recorded Investment	342	771	346
Related Allowance		30
Home Equity Line of Credit [Member] \| Year to Date [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,144	611	747
Interest Income Recognized			36
Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	889	598	1,398
Recorded Investment With No Allowance	118	125	339
Recorded Investment With Allowance	771	473	1,059
Total Recorded Investment	889	598	1,398
Related Allowance	289	378	430
Consumer, Other [Member] \| Year to Date [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	34	65	30
Interest Income Recognized			7
Consumer, Other [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	10	60	58
Recorded Investment With Allowance	10	60	58
Total Recorded Investment	10	60	58
Related Allowance	5	58	45
Year to Date [Member] \| Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	8,728	12,580	10,967
Interest Income Recognized	99	503	1,147
Year to Date [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	34,479	38,457	36,961
Interest Income Recognized	134	538	1,650
Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	8,671	13,098	8,785
Recorded Investment With No Allowance	8,071	4,783	8,176
Recorded Investment With Allowance	600	7,442	609
Total Recorded Investment	8,671	12,225	8,785
Related Allowance	$ 550	$ 1,775	$ 927

Name:	us-gaap_FinancingReceivableImpairedLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5258-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=egbn_CommercialRealEstateInvestmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=egbn_CommercialRealEstateOwnerOccupiedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=egbn_ConsumerOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_HomeEquityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=egbn_YearToDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: