Federally Assisted Acquisition of San Joaquin Bank - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Business Combinations [Abstract]
Remaining discount associated with SJB loans	$ 20.9
Expected cash flows	13.2
Remaining average lives of loan	4 years 10 months 24 days
Remaining average lives of loan	10 months 24 days
FDIC loss sharing asset	$ 14.2
Maximum contract life	1 year 6 months