Loans (Details) (USD $)	3 Months Ended
	Mar. 31, 2014 Item	Dec. 31, 2013	Mar. 31, 2013
Loans Receivable
Total	$ 2,907,684,000	$ 2,872,263,000	$ 2,189,468,000
Unearned Income	(8,254,000)	(7,864,000)
Total loans	2,899,430,000	2,864,399,000
Allowance for loan losses	(53,464,000)	(53,563,000)	(58,577,000)
Net loans	2,845,966,000	2,810,836,000
Held-for-sale loans included above	27,791,000	47,557,000	134,100,000
Covered loans, number of loan pool categories	4
Covered loans:
Gross loans	71,236,000	77,666,000	107,968,000
Allowance for loan losses	(1,926,000)	(3,943,000)	(4,326,000)
Net loans	69,310,000	73,723,000	103,642,000
Allowance for loan losses
Balances at beginning of period	53,563,000	52,397,000	63,285,000
Charge-offs	1,637,000	1,551,000	5,589,000
Recoveries on loans previously charged off	1,538,000	2,717,000	881,000
Net loan charge-offs	99,000	(1,166,000)	4,708,000
Balances at end of period	53,464,000	53,563,000	58,577,000
Net charge-offs of covered loans	1,600,000
Gross covered loan charge-offs	2,400,000
FDIC receivable portions on covered loans	768,000
Allowance for loan commitments
Balances at beginning of period	1,023,000	1,023,000	1,023,000
Balances at end of period	1,023,000	1,023,000	1,023,000
Ratios:
Net loan charge-offs to average net loans (annualized) (as a percent)	0.01%	(0.18%)	0.89%
Allowance for loan losses to gross loans at end of period (excluding loans held-for-sale) (as a percent)	1.86%	1.90%	2.85%
Net loan charge-offs to allowance for loan losses at end of period (as a percent)	0.19%	2.18%	8.04%
Net loan charge-offs to credit for loan losses and loan commitments (as a percent)	0.00%	0.00%	0.00%
ASC 310-30 loans
Covered loans:
Gross loans	2,451,000	2,686,000	775,000
Non-ASC 310-30 loans
Covered loans:
Gross loans	590,912,000	616,500,000	107,193,000
Loans with evidence of deterioration in credit quality
Covered loans:
Unpaid principal balance, before discount	13,400,000	14,900,000
Gross loans	2,451,000	2,686,000
Allowance for loan losses	(386,000)
Legacy Wilshire Loans
Loans Receivable
Total	2,314,321,000	2,253,077,000
Unearned Income	(8,254,000)	(7,864,000)
Total loans	2,306,067,000	2,245,213,000
Allowance for loan losses	(50,963,000)	(49,620,000)
Net loans	2,255,104,000	2,195,593,000
Held-for-sale loans included above	27,345,000	45,505,000
Allowance for loan losses
Balances at end of period	50,963,000	49,620,000
Loans Held-for-Sale
Loans Receivable
Total	27,800,000	47,600,000
Mirae Bank
Changes to the total discount related to loans acquired from Mirae Bank
Balance at beginning of period	34,201,000		3,448,000
Discount accretion income recognized	(2,816,000)		(228,000)
Disposals related to charge-offs	(172,000)		(74,000)
Balance at end of period	31,213,000		3,146,000
Changes to the accretable portion of the discount related to covered loans
Balance at beginning of period	31,450,000		3,275,000
Discount accretion income recognized	(2,791,000)		(228,000)
Disposals related to charge-offs	(2,000)		(74,000)
Balance at end of period	28,657,000		2,973,000
Mirae Bank | Acquired Loans
Loans Receivable
Total	71,236,000	77,812,000
Total loans	71,236,000	77,812,000
Allowance for loan losses	(1,926,000)	(3,943,000)
Net loans	69,310,000	73,869,000
Allowance for loan losses
Balances at end of period	1,926,000	3,943,000
BankAsiana | Acquired Loans
Loans Receivable
Total	151,667,000	161,640,000
Total loans	151,667,000	161,640,000
Allowance for loan losses	(346,000)
Net loans	151,321,000	161,640,000
Held-for-sale loans included above	257,000	2,052,000
Allowance for loan losses
Balances at end of period	346,000
Saehan Bancorp | Acquired Loans
Loans Receivable
Total	370,460,000	379,734,000
Total loans	370,460,000	379,734,000
Allowance for loan losses	(229,000)
Net loans	370,231,000	379,734,000
Held-for-sale loans included above	189,000
Allowance for loan losses
Balances at end of period	229,000
Construction loans
Loans Receivable
Total	43,277,000	40,367,000	34,030,000
Allowance for loan losses	(791,000)	(814,000)
Allowance for loan losses
Balances at end of period	791,000	814,000
Construction loans | Legacy Wilshire Loans
Loans Receivable
Total	37,505,000	35,337,000
Construction loans | Loans Receivable
Loans Receivable
Total	43,277,000	40,367,000
Construction loans | BankAsiana | Acquired Loans
Loans Receivable
Total	5,772,000	5,030,000
Real estate secured loans
Summary of loans
Loan maturity period	7 years
Loan principal and interest amortization period	25 years
Loans Receivable
Total	2,423,459,000	2,367,530,000	1,815,351,000
Allowance for loan losses	(39,164,000)	(41,401,000)
Allowance for loan losses
Balances at beginning of period	41,401,000
Charge-offs	672,000	552,000	4,405,000
Recoveries on loans previously charged off	1,028,000	2,038,000	215,000
Balances at end of period	39,164,000	41,401,000
Real estate secured loans | Minimum
Summary of loans
Loan-to-value ratio (as a percent)	60.00%
Prepayment penalty period from the date of the loan	3 years
Real estate secured loans | Maximum
Summary of loans
Loan-to-value ratio (as a percent)	70.00%
Prepayment penalty period from the date of the loan	5 years
Real estate secured loans | ASC 310-30 loans
Covered loans:
Gross loans	2,038,000	2,254,000	660,000
Real estate secured loans | Legacy Wilshire Loans
Loans Receivable
Total	1,907,761,000	1,837,985,000
Real estate secured loans | Mirae Bank | Acquired Loans
Loans Receivable
Total	66,387,000	71,493,000
Real estate secured loans | BankAsiana | Acquired Loans
Loans Receivable
Total	112,703,000	117,050,000
Real estate secured loans | Saehan Bancorp | Acquired Loans
Loans Receivable
Total	336,608,000	341,002,000
Commercial and industrial
Loans Receivable
Total	424,848,000	449,672,000	328,403,000
Allowance for loan losses	(13,353,000)	(11,238,000)
Allowance for loan losses
Balances at beginning of period	11,238,000
Charge-offs	964,000	997,000	1,183,000
Recoveries on loans previously charged off	510,000	679,000	658,000
Balances at end of period	13,353,000	11,238,000
Commercial and industrial | ASC 310-30 loans
Covered loans:
Gross loans	413,000	432,000	115,000
Commercial and industrial | Legacy Wilshire Loans
Loans Receivable
Total	354,274,000	367,450,000
Commercial and industrial | Mirae Bank | Acquired Loans
Loans Receivable
Total	4,847,000	6,316,000
Commercial and industrial | BankAsiana | Acquired Loans
Loans Receivable
Total	33,183,000	39,550,000
Commercial and industrial | Saehan Bancorp | Acquired Loans
Loans Receivable
Total	32,544,000	36,356,000
Lines of credit loans | Maximum
Summary of loans
Loan maturity period	1 year
Business term loans | Minimum
Summary of loans
Loan maturity period	1 year
Business term loans | Maximum
Summary of loans
Loan maturity period	7 years
Consumer loans
Loans Receivable
Total	16,100,000	14,694,000	11,684,000
Allowance for loan losses	(156,000)	(110,000)
Allowance for loan losses
Balances at beginning of period	110,000
Charge-offs	1,000	2,000	1,000
Recoveries on loans previously charged off			8,000
Balances at end of period	156,000	110,000
Consumer loans | Legacy Wilshire Loans
Loans Receivable
Total	14,781,000	12,305,000
Consumer loans | Mirae Bank | Acquired Loans
Loans Receivable
Total	2,000	3,000
Consumer loans | BankAsiana | Acquired Loans
Loans Receivable
Total	9,000	10,000
Consumer loans | Saehan Bancorp | Acquired Loans
Loans Receivable
Total	$ 1,308,000	$ 2,376,000