Note 3 - Investment Securities Available-for-Sale (Details) - Securities Available-for-sale - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Note 3 - Investment Securities Available-for-Sale (Details) - Securities Available-for-sale [Line Items]
Amortized Cost	$ 518,807	$ 377,933
Gross Unrealized gains	6,912	7,087
Gross unrealized losses	524,326	382,343
US Government Agencies Debt Securities [Member]
Note 3 - Investment Securities Available-for-Sale (Details) - Securities Available-for-sale [Line Items]
Amortized Cost	68,289	29,434
Gross Unrealized gains	879	500
Gross unrealized losses	69,078	29,894
Residential Mortgage Backed Securities [Member]
Note 3 - Investment Securities Available-for-Sale (Details) - Securities Available-for-sale [Line Items]
Amortized Cost	320,978	241,120
Gross Unrealized gains	2,172	1,716
Gross unrealized losses	322,020	240,320
US States and Political Subdivisions Debt Securities [Member]
Note 3 - Investment Securities Available-for-Sale (Details) - Securities Available-for-sale [Line Items]
Amortized Cost	114,137	106,983
Gross Unrealized gains	3,824	4,850
Gross unrealized losses	117,866	111,712
Corporate Debt Securities [Member]
Note 3 - Investment Securities Available-for-Sale (Details) - Securities Available-for-sale [Line Items]
Amortized Cost	15,096
Gross unrealized losses	15,018
Equity Investment Other [Member]
Note 3 - Investment Securities Available-for-Sale (Details) - Securities Available-for-sale [Line Items]
Amortized Cost	307	396
Gross Unrealized gains	37	21
Gross unrealized losses	$ 344	$ 417

No definition available.

Name:	egbn_Note3InvestmentSecuritiesAvailableforSaleDetailsSecuritiesAvailableforsaleLineItems
Namespace Prefix:	egbn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

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

- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

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

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=egbn_EquityInvestmentOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: