Note Other Real Estate Owned (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Other Real Estate Owned Rollforward [Line Items]
Balance at beginning of the period	$ 168,394		$ 188,855	$ 215,762	$ 188,855		$ 212,573
Write-downs in value	(4,773)			(11,798)	(8,228)		(16,584)
Additions	5,184			31,852	12,571		66,753
Sales	(26,684)			(28,837)	(50,660)		(55,636)
Other adjustments	(58)			(533)	(475)		(660)
Transfer to non-covered status	0	[1]	15,300		0	[2]
Ending balance	142,063		168,394	206,446	142,063		206,446
Non-covered loans | Mortgages
Other Real Estate Owned Rollforward [Line Items]
Balance at beginning of the period	127,426		147,849	163,282	147,849		160,044
Write-downs in value	(4,025)			(9,104)	(6,539)		(11,859)
Additions	2,546			24,662	5,530		50,916
Sales	(24,450)			(22,474)	(44,755)		(42,883)
Other adjustments	(29)			781	(617)		929
Transfer to non-covered status	15,333	[1]			15,333	[2]
Ending balance	116,801		127,426	157,147	116,801		157,147
Non-covered loans | Commercial / Construction
Other Real Estate Owned Rollforward [Line Items]
Balance at beginning of the period	25,635		21,411	22,554	21,411		20,401
Write-downs in value	(748)			(720)	(1,402)		(1,979)
Additions	2,638			3,084	7,041		7,622
Sales	(2,234)			(971)	(2,623)		(1,964)
Other adjustments	(29)			2	835		(131)
Transfer to non-covered status	0	[1]			0	[2]
Ending balance	25,262		25,635	23,949	25,262		23,949
Covered loans | Mortgages
Other Real Estate Owned Rollforward [Line Items]
Balance at beginning of the period	15,333		19,595	29,926	19,595		32,128
Write-downs in value	0			(1,974)	(287)		(2,746)
Additions	0			4,106	0		8,215
Sales	0			(5,392)	(3,282)		(10,789)
Other adjustments	0			(1,316)	(693)		(1,458)
Transfer to non-covered status	(15,333)	[1]			(15,333)	[2]
Ending balance	$ 0		$ 15,333	$ 25,350	$ 0		$ 25,350

[1] Represents the reclassification of OREOs to the non-covered category, pursuant to the Termination Agreement of all shared-loss agreements with the Federal Deposit Insurance Corporation related to loans acquired from Westernbank, that was completed on May 22, 2018.

[2] Represents the reclassification of OREOs to the non-covered category, pursuant to the Termination Agreement of all shared-loss agreements with the Federal Deposit Insurance Corporation related to loans acquired from Westernbank, that was completed on May 22, 2018.