INVESTMENT SECURITIES - OTTI Losses on Available-for-Sale Debt Securities (Detail) - USD ($) $ in Thousands		3 Months Ended					9 Months Ended
		Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule Of Available For Sale Securities [Line Items]
Total other-than-temporary impairment losses		$ 0			$ 0		$ (1,845)	$ (29,521)
Credit losses on debt securities for which an OTTI was no previously recognized		0			0		0	12,856
Portion of loss previously recognized in other comprehensive income		0			231		4,842	(16,037)
Net impairment losses recognized in earnings	[1]	0			(231)		(6,687)	(13,484)
Mortgage Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Credit losses on debt securities for which an OTTI was no previously recognized		0
Mortgage Backed Securities Issued By Private Enterprises [Member]
Schedule Of Available For Sale Securities [Line Items]
Credit losses on debt securities for which an OTTI was no previously recognized					0		0	0
Net impairment losses recognized in earnings							(400)	(600)
US States And Political Subdivisions Member [Member]
Schedule Of Available For Sale Securities [Line Items]
Credit losses on debt securities for which an OTTI was no previously recognized		$ 0			$ 0		0	12,856
Net impairment losses recognized in earnings			$ (6,300)	$ (3,000)		$ (12,900)	$ (6,300)	$ (12,900)

[1] For the nine-month periods ended September 30, 2016 and 2015, approximately $6.3 million and $12.9 million, respectively, of the credit impairment recognized in earnings consisted of credit losses on Puerto Rico Government debt securities and $0.4 million and $0.6 million, respectively, was associated with credit losses on private label MBS.