Note Other Real Estate Owned (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Write Downs	$ 3,071	$ 5,792	[1]	$ 11,299	$ 22,376	[1]
Hurricane
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Write Downs		2,700			2,700
Mortgages | Hurricane
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Write Downs		1,400			1,400
Commercial / Construction | Hurricane
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Write Downs		$ 1,300			$ 1,300

[1] Includes $2.7 million related to the damages from Hurricane Maria, of which $1.3 million were for commercial and $1.4 million for residential.