Fair value and gross unrealized losses of investment securities held-to-maturity, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	$ 86,131	$ 2,365
Less than 12 months Gross Unrealized Losses	14,431	35
12 months or more Fair Value	12,039	19,118
12 months or more Gross Unrealized Losses	6,736	427
Total Fair Value	98,170	21,483
Total Gross Unrealized Losses	21,167	462
Puerto Rico States And Political Subdivisions Debt Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	61,797	2,365
Less than 12 months Gross Unrealized Losses	13,515	35
12 months or more Fair Value	12,039	19,118
12 months or more Gross Unrealized Losses	6,736	427
Total Fair Value	73,836	21,483
Total Gross Unrealized Losses	20,251	462
Collateralized Mortgage Obligations Issued By Private Enterprise [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	0	0
Less than 12 months Gross Unrealized Losses	0	0
12 months or more Fair Value	0	0
12 months or more Gross Unrealized Losses	0	0
Total Fair Value	0	0
Total Gross Unrealized Losses	0	0
US Treasury Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	0	0
Less than 12 months Gross Unrealized Losses	0	0
12 months or more Fair Value	0	0
12 months or more Gross Unrealized Losses	0	0
Total Fair Value	0	0
Total Gross Unrealized Losses	0	0
Other Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	24,334	0
Less than 12 months Gross Unrealized Losses	916	0
12 months or more Fair Value	0	0
12 months or more Gross Unrealized Losses	0	0
Total Fair Value	24,334	0
Total Gross Unrealized Losses	$ 916	$ 0