Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Activity in the Allowance for Covered Loan Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Allowance for Covered Loan Losses [Roll Forward]
Balance at beginning of period	$ 2,507	$ 1,878	$ 3,026	$ 2,131
Provision for covered loan losses before benefit attributable to FDIC loss share agreements	(702)	(1,094)	(2,648)	(1,623)
Benefit attributable to FDIC loss share agreements	562	875	2,119	1,298
Net provision for covered loan losses	(140)	(219)	(529)	(325)
Increase/decrease in FDIC indemnification liability/asset	(562)	(875)	(2,119)	(1,298)
Loans charged-off	(143)	(140)	(373)	(377)
Recoveries of loans charged-off	750	1,571	2,407	2,084
Net recoveries	607	1,431	2,034	1,707
Balance at end of period	$ 2,412	$ 2,215	$ 2,412	$ 2,215