Note 24 - Parent Company Financial Information (Details) - Condensed Statements of Cash Flows (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows From Operating Activities
Net Income	$ 54,258,000us-gaap_NetIncomeLoss	$ 47,007,000us-gaap_NetIncomeLoss	$ 35,289,000us-gaap_NetIncomeLoss
Excess tax benefit on stock-based compensation	(978,000)	(410,000)	(369,000)
(Increase) decrease in other assets	(12,631,000)	(26,000)	3,797,000
Increase (decrease) in other liabilities	1,856,000	10,850,000	1,818,000
Net cash (used in) operating activities	59,507,000	258,677,000	15,820,000
Cash Flows From Investing Activities
Net cash used in investing activities	(725,725,000)	(600,736,000)	(446,567,000)
Cash Flows From Financing Activities
Issuance of common stock	144,093,000		42,956,000
Issuance of Series C Preferred Stock	15,300,000
Cash paid in lieu of fractional shares		11,000egbn_PaymentsInLieuOfFractionalShares
Proceeds from exercise of stock options	2,313,000	1,984,000	1,685,000
Preferred stock dividends	(614,000)us-gaap_DividendsPreferredStock	(566,000)us-gaap_DividendsPreferredStock	(566,000)us-gaap_DividendsPreferredStock
Excess tax benefit on stock-based compensation	978,000	410,000	369,000
Proceeds from employee stock purchase plan	621,000us-gaap_ProceedsFromStockPlans	543,000us-gaap_ProceedsFromStockPlans	447,000us-gaap_ProceedsFromStockPlans
Net cash provided by financing activities	615,283,000	309,685,000	537,670,000
Net Increase in Cash	(50,935,000)	(32,374,000)	106,923,000
Cash and Cash Equivalents	256,025,000	306,960,000	339,334,000
Beginning of Period [Member] \| Parent Company [Member]
Cash Flows From Financing Activities
Cash and Cash Equivalents	25,833,000	25,518,000	16,498,000
End of Period [Member] \| Parent Company [Member]
Cash Flows From Financing Activities
Cash and Cash Equivalents	51,549,000	25,833,000	25,518,000
Parent Company [Member]
Cash Flows From Operating Activities
Net Income	54,258,000	47,007,000	35,289,000
Equity in undistributed income of subsidiary	(56,545,000)	(48,252,000)	(36,564,000)
Excess tax benefit on stock-based compensation	(978,000)	(410,000)	(369,000)
(Increase) decrease in other assets	(1,731,000)	353,000	(34,000)
Increase (decrease) in other liabilities	1,803,000	67,000	(50,000)
Net cash (used in) operating activities	(3,193,000)	(1,235,000)	(1,728,000)
Cash Flows From Investing Activities
Investment in subsidiary (net)	(203,782,000)	(810,000)	(34,143,000)
Net cash used in investing activities	(203,782,000)	(810,000)	(34,143,000)
Cash Flows From Financing Activities
Issuance of common stock	144,093,000		42,956,000
Issuance of Series C Preferred Stock	15,300,000
Issuance in long-term borrowings	70,000,000
Cash paid in lieu of fractional shares		(11,000)
Proceeds from exercise of stock options	2,313,000	1,984,000	1,685,000
Preferred stock dividends	(614,000)	(566,000)	(566,000)
Excess tax benefit on stock-based compensation	978,000	410,000	369,000
Proceeds from employee stock purchase plan	621,000	543,000	447,000
Net cash provided by financing activities	232,691,000	2,360,000	44,891,000
Net Increase in Cash	25,716,000	315,000	9,020,000
Cash and Cash Equivalents	$ 8,739,000	$ 8,693,000

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