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		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Allowance for Covered Loan Losses [Roll Forward]
Balance at beginning of period	$ 2,412	$ 2,215	$ 3,026	$ 2,131
Provision for covered loan losses before benefit attributable to FDIC loss share agreements	(847)	(1,716)	(3,495)	(3,339)
Benefit attributable to FDIC loss share agreements	677	1,373	2,796	2,671
Net provision for covered loan losses	(170)	(343)	(699)	(668)
Increase/decrease in FDIC indemnification liability/asset	(677)	(1,373)	(2,796)	(2,671)
Loans charged-off	(918)	(287)	(1,291)	(664)
Recoveries of loans charged-off	775	2,706	3,182	4,790
Net (charge-offs) recoveries	(143)	2,419	1,891	4,126
Balance at end of period	$ 1,422	$ 2,918	$ 1,422	$ 2,918