Amortized cost, gross unrealized gains and losses, approximate fair value, weighted average yield and contractual maturities of investment securities held-to-maturity (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 112,893	$ 140,496
Gross Unrealized Gains	1,382	264
Gross Unrealized Losses	11,155	20,072
Investment securities held-to-maturity, fair value	103,120	120,688
Weighted Average Yield	3.35%	3.40%
US Treasury Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
US Treasury Securities [Member] | Within One Year From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
US Treasury Securities [Member] | More Than One And Within Five Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
US Treasury Securities [Member] | More Than Five And Within Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
US Treasury Securities [Member] | More Than Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
Collateralized Mortgage Obligations Issued By Private Enterprise [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
Collateralized Mortgage Obligations Issued By Private Enterprise [Member] | Within One Year From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
Collateralized Mortgage Obligations Issued By Private Enterprise [Member] | More Than One And Within Five Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
Collateralized Mortgage Obligations Issued By Private Enterprise [Member] | More Than Five And Within Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
Collateralized Mortgage Obligations Issued By Private Enterprise [Member] | More Than Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	101	115
Gross Unrealized Gains	6	7
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	107	122
Weighted Average Yield	5.45%	5.45%
Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member] | More Than Five And Within Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	101
Gross Unrealized Gains	6
Gross Unrealized Losses	0
Investment securities held-to-maturity, fair value	107
Weighted Average Yield	5.45%
Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member] | More Than Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	115
Gross Unrealized Gains	0	7
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	122
Weighted Average Yield	0.00%	5.45%
Other Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,500	26,500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	646
Investment securities held-to-maturity, fair value	1,500	25,854
Weighted Average Yield	1.13%	3.37%
Other Securities [Member] | Within One Year From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	250	26,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	645
Investment securities held-to-maturity, fair value	250	25,355
Weighted Average Yield	1.20%	3.41%
Other Securities [Member] | More Than One And Within Five Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,250	500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	1
Investment securities held-to-maturity, fair value	1,250	499
Weighted Average Yield	1.12%	1.33%
Other Securities [Member] | More Than Five And Within Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
Other Securities [Member] | More Than Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Investment securities held-to-maturity, fair value	0	0
Weighted Average Yield	0.00%	0.00%
US Government Sponsored Enterprises Debt Securities Member
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Investment securities held-to-maturity, fair value	0
Weighted Average Yield	0.00%
US Government Sponsored Enterprises Debt Securities Member | Within One Year From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Investment securities held-to-maturity, fair value	0
Weighted Average Yield	0.00%
US Government Sponsored Enterprises Debt Securities Member | More Than One And Within Five Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Investment securities held-to-maturity, fair value	0
Weighted Average Yield	0.00%
US Government Sponsored Enterprises Debt Securities Member | More Than Five And Within Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Investment securities held-to-maturity, fair value	0
Weighted Average Yield	0.00%
US Government Sponsored Enterprises Debt Securities Member | More Than Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Investment securities held-to-maturity, fair value	0
Weighted Average Yield	0.00%
Puerto Rico States And Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	111,292	113,881
Gross Unrealized Gains	1,376	257
Gross Unrealized Losses	11,155	19,426
Investment securities held-to-maturity, fair value	101,513	94,712
Weighted Average Yield	3.38%	3.40%
Puerto Rico States And Political Subdivisions Debt Securities [Member] | Within One Year From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	12,740	12,570
Gross Unrealized Gains	0	0
Gross Unrealized Losses	5	12
Investment securities held-to-maturity, fair value	12,735	12,558
Weighted Average Yield	2.11%	2.06%
Puerto Rico States And Political Subdivisions Debt Securities [Member] | More Than One And Within Five Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	12,830	12,060
Gross Unrealized Gains	0	0
Gross Unrealized Losses	412	984
Investment securities held-to-maturity, fair value	12,418	11,076
Weighted Average Yield	5.95%	5.91%
Puerto Rico States And Political Subdivisions Debt Securities [Member] | More Than Five And Within Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	21,325	20,015
Gross Unrealized Gains	0	0
Gross Unrealized Losses	5,240	5,251
Investment securities held-to-maturity, fair value	16,085	14,764
Weighted Average Yield	6.09%	6.06%
Puerto Rico States And Political Subdivisions Debt Securities [Member] | More Than Ten Years From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	64,397	69,236
Gross Unrealized Gains	1,376	257
Gross Unrealized Losses	5,498	13,179
Investment securities held-to-maturity, fair value	$ 60,275	$ 56,314
Weighted Average Yield	2.22%	2.43%