BUSINESS COMBINATION (Details) (USD $)	3 Months Ended			0 Months Ended	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Jan. 17, 2014 MetroCorp	Mar. 31, 2014 MetroCorp item
Business combination
Number of branches					19
Number of subsidiaries					2
Percentage of purchase consideration satisfied in stock				66.67%
Percentage of purchase consideration satisfied in cash				33.33%
Fair value of the consideration transferred				$ 291,400,000
Consideration transferred in the acquisition (in shares)	5,583,093			5,583,093
Fair value of common stock issued as part of consideration transferred	190,830,000			190,800,000
Consideration transferred in cash				89,400,000
Additional cash given to acquiree's stock option holders as part of consideration transferred				2,400,000
Amount given for warrant's assumed as part of consideration transferred				8,800,000
Goodwill recorded as a result of the business combination	458,467,000	337,438,000	337,438,000	121,000,000
Fair value of assets acquired				1,700,000,000
Cash and due from banks				230,300,000
Investment securities available for sale				64,300,000
FHLB stock				2,700,000
Loans receivable				1,190,000,000	1,190,000,000
Fixed assets				8,600,000
Premiums on deposits acquired				8,600,000
OREO				9,400,000
Bank owned life insurance				30,000,000
Deferred tax assets				13,000,000
Other assets				16,700,000
Fair value of liabilities acquired				1,410,000,000
Deposits				1,320,000,000
FHLB advances				10,000,000
Repurchase agreements				25,900,000
Junior subordinated debts				29,100,000
Other liabilities				$ 22,700,000