BUSINESS COMBINATIONS (Details Textual) $ in Thousands		1 Months Ended		9 Months Ended
	Jun. 12, 2015 USD ($)	May. 22, 2015 USD ($)	Jun. 30, 2014 USD ($) shares	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Goodwill, excess of the merger consideration over fair value of net assets			$ 28,100	$ 87,701	$ 58,879	$ 63,547
Issuance of common stock, fair value				$ 0	$ 34,474
Coastal Bank share Inc [Member]
Shares to receive for each share of Prosperity common stock pursuant to the merger agreement			0.4671
Issuance of common stock, shares | shares			1,598,998
Issuance of common stock, fair value			$ 34,500
Fair value of loans acquired			279,400
Net of loans acquired			$ 16,700
Estimated discount			5.64%
Accretable yield			$ 29,300
Coastal Bank share Inc [Member] | Warrant [Member]
Cash in exchange for outstanding warrants			$ 2,800
Merchants and Southern Banks of Florida [Member]
Number of banking locations		13
Goodwill, excess of the merger consideration over fair value of net assets		$ 0
Fair value of loans acquired		191,500
Net of loans acquired		$ 8,500
Estimated discount		4.25%
Accretable yield		$ 17,400
Payments to Acquire Businesses, Gross		50,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		14,614
Business Combination, Consideration Transferred		50,000
Merchants and Southern Banks of Florida [Member] | Scenario, Previously Reported [Member]
Goodwill, excess of the merger consideration over fair value of net assets		12,917
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		10,934
Business Combination, Consideration Transferred		$ 50,000
Bank Of America [Member]
Goodwill, excess of the merger consideration over fair value of net assets	$ 0
Fair value of loans acquired	4,400
Net of loans acquired	$ 4,400
Number Of Bank Branches	18
Deposit Premium On Deposits Assumed	3.00%
Average Daily Deposits Period	15 days
Payments to Acquire Businesses, Gross	$ 20,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	10,348
Business Combination, Consideration Transferred	20,002
Bank Of America [Member] | Scenario, Previously Reported [Member]
Goodwill, excess of the merger consideration over fair value of net assets	10,582
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	$ 10,917