Note FDIC loss share expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure F D I C Loss Share Expense Income [Abstract]
Amortization of loss share indemnification asset		$ (934)
80% mirror accounting on credit impairment losses		104
80% mirror accounting on reimbursable expenses		537
80% mirror accounting on recoveries on covered assets, including rental income on OREOs, subject to reimbursement to the FDIC		(1,658)
Change in true-up payment obligation		(6,112)
Other		36
FDIC loss share (expense) income	$ 0	$ (8,027)