BUSINESS COMBINATION (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015 entity	Mar. 31, 2014 entity	Jan. 17, 2014	Dec. 31, 2014
Business combination
Number of business combinations	0	1
Purchase consideration
Consideration transferred in the acquisition (in shares)		5,583,093
Issuance of 5,583,093 shares pursuant to MetroCorp acquisition		$ 190,830,000
Assets acquired and liabilities assumed
Goodwill recorded as a result of the business combination	469,433,000	458,467,000		469,433,000
MetroCorp
Purchase consideration
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
Issuance of 5,583,093 shares pursuant to MetroCorp acquisition			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
Fair value of warrants assumed as part of consideration transferred			8,800,000
Assets acquired and liabilities assumed
Fair value of assets acquired			1,700,000,000
Fair value of liabilities acquired			1,410,000,000
Goodwill recorded as a result of the business combination			121,000,000	132,000,000
MetroCorp | Adjustments
Assets acquired and liabilities assumed
Deferred tax assets				(10,300,000)
Bank owned life insurance				$ (700,000)