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	Sep. 30, 2013	Dec. 31, 2012
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 140,355	$ 142,817
Gross Unrealized Gains	61	1,878
Gross Unrealized Losses	21,167	462
Fair Value	119,249	144,233
Weighted Average Yield	3.40%	4.82%
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
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
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
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
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
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
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
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
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
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
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	122	140
Gross Unrealized Gains	7	4
Gross Unrealized Losses	0	0
Fair Value	129	144
Weighted Average Yield	5.45%	5.00%
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	122	140
Gross Unrealized Gains	7	4
Gross Unrealized Losses	0	0
Fair Value	129	144
Weighted Average Yield	5.45%	5.00%
Other Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	26,500	26,500
Gross Unrealized Gains	0	31
Gross Unrealized Losses	916	0
Fair Value	25,584	26,531
Weighted Average Yield	3.37%	3.38%
Other Securities [Member] | Within One Year From Balance Sheet Date [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	26,000	250
Gross Unrealized Gains	0	0
Gross Unrealized Losses	913	0
Fair Value	25,087	250
Weighted Average Yield	3.41%	0.86%
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	500	26,250
Gross Unrealized Gains	0	31
Gross Unrealized Losses	3	0
Fair Value	497	26,281
Weighted Average Yield	1.39%	3.40%
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
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
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
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
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
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
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
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	113,733	116,177
Gross Unrealized Gains	54	1,843
Gross Unrealized Losses	20,251	462
Fair Value	93,536	117,558
Weighted Average Yield	3.40%	5.15%
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	2,570	2,420
Gross Unrealized Gains	0	8
Gross Unrealized Losses	33	0
Fair Value	2,537	2,428
Weighted Average Yield	5.80%	5.74%
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	22,060	21,335
Gross Unrealized Gains	0	520
Gross Unrealized Losses	1,143	19
Fair Value	20,917	21,836
Weighted Average Yield	3.73%	3.63%
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	20,015	18,780
Gross Unrealized Gains	0	866
Gross Unrealized Losses	5,354	5
Fair Value	14,661	19,641
Weighted Average Yield	6.06%	6.03%
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	69,088	73,642
Gross Unrealized Gains	54	449
Gross Unrealized Losses	13,721	438
Fair Value	$ 55,421	$ 73,653
Weighted Average Yield	2.43%	5.35%