NON-COVERED LOANS AND ALLOWANCE FOR LOAN LOSSES (Details 3) (USD $)	9 Months Ended			3 Months Ended			9 Months Ended							0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Non-covered loans		Sep. 30, 2013 Non-covered loans	Sep. 30, 2014 Non-covered loans		Sep. 30, 2013 Non-covered loans	Dec. 31, 2013 Non-covered loans		Jan. 17, 2014 MetroCorp	Sep. 30, 2014 MetroCorp Non-covered loans	Jan. 17, 2014 MetroCorp Covered Loans under ASC 310-30 Subject to Allowance for Loan Losses Non-covered loans	Sep. 30, 2014 Residential Non-covered loans	Dec. 31, 2013 Residential Non-covered loans	Sep. 30, 2014 Commercial Real Estate ("CRE") Non-covered loans	Dec. 31, 2013 Commercial Real Estate ("CRE") Non-covered loans
Credit Risk and Concentrations
Percentage of non-covered commercial real estate loans and non-covered residential loans secured by real properties located in California				80.00%			80.00%
Non-Covered Loans				$ 19,351,556,000	[1]		$ 19,351,556,000	[1]		$ 15,678,317,000	[1]				$ 4,649,295,000	$ 4,185,309,000	$ 5,949,350,000	$ 4,585,077,000
Purchased Loans
Loans purchased during the period							108,900,000
Acquired Loans
Loans acquired during the period												1,190,000,000
Acquired loans accounted (as a percent)														6.00%
PCI loans													55,500,000
Loans Held for Sale
Total loans held for sale	239,649,000		204,970,000	239,600,000			239,600,000			205,000,000
Proceeds from the sales of Loans held for sale, including loans reclassified to loans held for sale				232,000,000		0	558,300,000		6,300,000
Net gain from sale of loans held for sale during the period				6,200,000			14,700,000		1,000
Loans receivable reclassified to loans held for sale	$ 460,828,000	$ 13,912,000		$ 0			$ 460,800,000

[1] Loans net of ASC 310-30 discount.