INVESTMENT SECURITIES - Available-For-Sale Investments' Fair Value And Gross Unrealized Losses (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	$ 48,474	$ 1,232,981
Unrealized Losses Less than 12 months	79	59,230
Fair Value 12 months or more	1,010,786	143,119
Unrealized Losses 12 months or more	42,467	33,875
Total Fair Value	1,059,260	1,376,100
Total Unrealized Losses	42,546	93,105
Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months		33
Unrealized Losses Less than 12 months		2
Fair Value 12 months or more		0
Unrealized Losses 12 months or more		0
Total Fair Value		33
Total Unrealized Losses		2
Debt Securities [Member] | Puerto Rico Government Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	0	23,156
Unrealized Losses Less than 12 months	0	5,977
Fair Value 12 months or more	42,335	28,174
Unrealized Losses 12 months or more	17,990	13,701
Total Fair Value	42,335	51,330
Total Unrealized Losses	17,990	19,678
Debt Securities [Member] | US States And Political Subdivisions [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair Value Less than 12 months	46,436	175,369
Unrealized Losses Less than 12 months	74	8,913
Fair Value 12 months or more	257,996	74,126
Unrealized Losses 12 months or more	6,222	5,863
Total Fair Value	304,432	249,495
Total Unrealized Losses	6,296	14,776
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		81
Unrealized Losses 12 months or more		1
Total Fair Value		81
Total Unrealized Losses		1
Mortgage Backed Securities [Member] | Mortgage Backed Securities Issued By Private Enterprises [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	33,536	40,738
Unrealized Losses 12 months or more	12,141	14,310
Total Fair Value	33,536	40,738
Total Unrealized Losses	12,141	14,310
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	2,038	748,215
Unrealized Losses Less than 12 months	5	33,626
Fair Value 12 months or more	541,642	0
Unrealized Losses 12 months or more	4,854	0
Total Fair Value	543,680	748,215
Total Unrealized Losses	4,859	33,626
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	0	286,208
Unrealized Losses Less than 12 months	0	10,712
Fair Value 12 months or more	135,277	0
Unrealized Losses 12 months or more	1,260	0
Total Fair Value	135,277	286,208
Total Unrealized Losses	$ 1,260	$ 10,712