Note 5 - Loans and Allowance for Credit Losses - Allowance for Credit Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Balance	$ 59,074	$ 52,687
Loans charged-off	(700)	(1,406)
Recoveries of loans previously charged-off	77	284
Net loans (charged-off) recoveries	(623)	(1,122)
Provision for credit losses	1,397	3,043
Balance	59,848	54,608
Individually evaluated for impairment			$ 5,268	$ 4,548
Collectively evaluated for impairment			54,580	50,060
Balance	59,848	54,608	59,848	54,608
Commercial Portfolio Segment [Member]
Balance	14,700	11,563
Loans charged-off	(137)	(805)
Recoveries of loans previously charged-off	13	72
Net loans (charged-off) recoveries	(124)	(733)
Provision for credit losses	7	2,792
Balance	14,583	13,622
Individually evaluated for impairment			3,030	2,922
Collectively evaluated for impairment			11,553	10,700
Balance	14,700	11,563	14,583	13,622
Income Producing Portfolio Segment [Member]
Balance	21,105	14,122
Loans charged-off	(500)	(590)
Recoveries of loans previously charged-off	50	4
Net loans (charged-off) recoveries	(450)	(586)
Provision for credit losses	729	2,258
Balance	21,384	15,794
Individually evaluated for impairment			1,488	868
Collectively evaluated for impairment			19,896	14,926
Balance	21,105	14,122	21,384	15,794
Owner Occupied Portfolio Segment [Member]
Balance	4,010	3,279
Loans charged-off
Recoveries of loans previously charged-off	1	1
Net loans (charged-off) recoveries	1	1
Provision for credit losses	15	651
Balance	4,026	3,931
Individually evaluated for impairment			350	360
Collectively evaluated for impairment			3,676	3,571
Balance	4,010	3,279	4,026	3,931
Residential Portfolio Segment [Member]
Balance	1,284	1,268
Loans charged-off
Recoveries of loans previously charged-off	2	2
Net loans (charged-off) recoveries	2	2
Provision for credit losses	(180)	(219)
Balance	1,106	1,051
Individually evaluated for impairment
Collectively evaluated for impairment			1,106	1,051
Balance	1,284	1,268	1,106	1,051
Construction Portfolio Segment [Member]
Balance	16,487	21,088
Loans charged-off
Recoveries of loans previously charged-off	3	196
Net loans (charged-off) recoveries	3	196
Provision for credit losses	866	(2,818)
Balance	17,356	18,466
Individually evaluated for impairment			350	310
Collectively evaluated for impairment			17,006	18,156
Balance	16,487	21,088	17,356	18,466
Home Equity Portfolio Segment [Member]
Balance	1,328	1,292
Loans charged-off		(4)
Recoveries of loans previously charged-off	1	1
Net loans (charged-off) recoveries	1	(3)
Provision for credit losses	(241)	194
Balance	1,088	1,483
Individually evaluated for impairment				88
Collectively evaluated for impairment			1,088	1,395
Balance	1,328	1,292	1,088	1,483
Other Consumer Portfolio Segment [Member]
Balance	160	75
Loans charged-off	(63)	(7)
Recoveries of loans previously charged-off	7	8
Net loans (charged-off) recoveries	(56)	1
Provision for credit losses	201	185
Balance	305	261
Individually evaluated for impairment			50
Collectively evaluated for impairment			255	261
Balance	$ 160	$ 75	$ 305	$ 261

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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

- Definition

Amount of other addition (reduction) in allowance reserve for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ References

+ Details

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

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

+ Details

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

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

+ Details

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

- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=egbn_IncomeProducingPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=egbn_OwnerOccupiedPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=egbn_ConstructionPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=egbn_HomeEquityPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=egbn_OtherConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: