NON-COVERED LOANS AND ALLOWANCE FOR LOAN LOSSES (Details 3) (USD $)	3 Months Ended							0 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013		Mar. 31, 2014 MetroCorp	Jan. 17, 2014 MetroCorp	Jan. 17, 2014 MetroCorp Loans accounted for under ASC 310-30	Jan. 17, 2014 MetroCorp Loans accounted for under ASC 310-30	Mar. 31, 2014 Residential	Dec. 31, 2013 Residential	Mar. 31, 2014 Commercial Real Estate ("CRE")	Dec. 31, 2013 Commercial Real Estate ("CRE")
Credit Risk and Concentrations
Percentage of non-covered commercial real estate loans and non-covered residential loans secured by real properties located in California	81.00%
Loans receivable, excluding covered loans, gross	$ 17,308,411,000	[1]		$ 15,678,317,000	[1]					$ 4,349,486,000	$ 4,185,309,000	$ 5,519,920,000	$ 4,585,077,000
Purchased Loans
Loans purchased during the period	61,700,000
Carrying amount of loans purchased during the period	60,500,000
Acquired Loans
Loans acquired during the period						1,190,000,000	1,190,000,000
Acquired loans accounted (as a percent)								94.00%	6.00%
Loans Held for Sale
Total loans held for sale	577,353,000			204,970,000
Proceeds from the sales of Loans held for sale, including loans reclassified to loans held for sale	135,800,000		6,300,000
Net gain from sale of loans held for sale during the period	3,500,000		1,000
Loans receivable reclassified to loans held for sale	$ 433,841,000		$ 21,855,000

[1] Loans net of ASC 310-30 discount