INVESTMENT SECURITIES - Available-For-Sale Investments' Fair Value And Gross Unrealized Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	$ 426,813	$ 48,474
Unrealized Losses Less than 12 months	1,547	79
Fair Value 12 months or more	450,633	1,010,786
Unrealized Losses 12 months or more	39,616	42,467
Total Fair Value	877,446	1,059,260
Total Unrealized Losses	41,163	42,546
Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	0	0
Unrealized Losses Less than 12 months	0	0
Fair Value 12 months or more	0	0
Unrealized Losses 12 months or more	0	0
Total Fair Value	0	0
Total Unrealized Losses	0	0
Debt Securities [Member] | Puerto Rico Government Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	0	0
Unrealized Losses Less than 12 months	0	0
Fair Value 12 months or more	36,314	42,335
Unrealized Losses 12 months or more	24,070	17,990
Total Fair Value	36,314	42,335
Total Unrealized Losses	24,070	17,990
Debt Securities [Member] | US States And Political Subdivisions Member [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	4,999	46,436
Unrealized Losses Less than 12 months	0	74
Fair Value 12 months or more	261,252	257,996
Unrealized Losses 12 months or more	2,955	6,222
Total Fair Value	266,251	304,432
Total Unrealized Losses	2,955	6,296
Mortgage Backed Securities [Member] | Collateralized Mortgage Obligations Member
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months		0
Unrealized Losses Less than 12 months		0
Fair Value 12 months or more		0
Unrealized Losses 12 months or more		0
Total Fair Value		0
Total Unrealized Losses		0
Mortgage Backed Securities [Member] | Other-mortgage pass-through trust certificates [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	0	0
Unrealized Losses Less than 12 months	0	0
Fair Value 12 months or more	31,716	33,536
Unrealized Losses 12 months or more	11,296	12,141
Total Fair Value	31,716	33,536
Total Unrealized Losses	11,296	12,141
Mortgage Backed Securities [Member] | Federal National Mortgage Association Certificates And Obligations F N M A [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	311,339	2,038
Unrealized Losses Less than 12 months	1,195	5
Fair Value 12 months or more	99,932	541,642
Unrealized Losses 12 months or more	1,087	4,854
Total Fair Value	411,271	543,680
Total Unrealized Losses	2,282	4,859
Mortgage Backed Securities [Member] | Federal Home Loan Mortgage Corporation Certificates And Obligations F H L M C [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	110,475	0
Unrealized Losses Less than 12 months	352	0
Fair Value 12 months or more	21,419	135,277
Unrealized Losses 12 months or more	208	1,260
Total Fair Value	131,894	135,277
Total Unrealized Losses	$ 560	$ 1,260