Federal Home Loan Bank Advances and Other Borrowings - Additional Information (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Fixed bank advances	$ 15,000,000	$ 25,000,000
Interest rate of Company's advances	0.82%	0.59%
Interest rate of Company's advances		0.82%
Weighted average rate of Company's advances		0.73%
Variable bank advances	380,000,000	225,000,000
Advances from FHLB that were variable, weighted average interest rate	0.11%	0.06%
Federal funds purchased	70,000,000
Advances from FHLB collateralized	1,670,000,000	740,100,000
Amount of additional available borrowing	509,000,000
Amount of available line of credit with Federal Reserve Bank	89,300,000
San Francisco
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
FHLB stock	$ 18,600,000	$ 14,400,000