Covered Loans - Additional Information (Detail) (USD $)	6 Months Ended			6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Jun. 30, 2014 Expected Indemnification Payments [Member]	Jun. 30, 2013 Expected Indemnification Payments [Member]	Jun. 30, 2014 To Be Amortized Against Future Accreted Interest Income [Member]	Jun. 30, 2013 To Be Amortized Against Future Accreted Interest Income [Member]
Covered Loans [Line Items]
Covered loans	$ 171,148,000	$ 217,832,000	$ 288,577,000
Allowance for loan losses related to the acquired loans	0
Outstanding covered loans including principal, interest, fees and penalties	290,600,000	406,300,000
Percentage of prospective yield adjustments offset	80.00%
Loss sharing asset	51,400,000
Loss sharing asset, FDIC indemnification asset	45,900,000			17,000,000	63,800,000	28,900,000	25,800,000
Loss sharing asset, loss share receivable	$ 5,500,000
Percentage of increase in indemnification asset measured as a result of impairment	80.00%