Allowance for loan losses ending balance and the loan balance by portfolio segments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Jun. 30, 2012	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	$ 761,172		$ 766,030	$ 815,308		$ 772,921	$ 746,847	$ 793,225
Loans held-in-portfolio:
Loans held-in-portfolio	24,657,720			24,951,299
Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	107,424			58,986
Ending balance: loans collectively evaluated for impairment	528,875			631,377
Allowance for loan losses	636,299			690,363
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	1,269,975			1,226,021
Ending balance: loans collectively evaluated for impairment	19,483,878			19,376,575
Loans held-in-portfolio	20,753,853	[1]		20,602,596	[1]
Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	15,294			27,086
Ending balance: loans collectively evaluated for impairment	109,579			97,859
Allowance for loan losses	124,873			124,945
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	120,510			76,798
Ending balance: loans collectively evaluated for impairment	3,783,357			4,271,905
Loans held-in-portfolio	3,903,867			4,348,703
PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	570,127			578,347
Loans held-in-portfolio:
Loans held-in-portfolio	18,947,626			19,188,842
PUERTO RICO | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	91,008			43,348
Ending balance: loans collectively evaluated for impairment	354,246			410,054
Allowance for loan losses	445,254		446,557	453,402		443,590	414,903	455,431
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	1,084,260			929,868
Ending balance: loans collectively evaluated for impairment	13,959,499			13,910,271
Loans held-in-portfolio	15,043,759			14,840,139
PUERTO RICO | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	15,294			27,086
Ending balance: loans collectively evaluated for impairment	109,579			97,859
Allowance for loan losses	124,873		117,495	124,945		80,419	57,169	0
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	120,510			76,798
Ending balance: loans collectively evaluated for impairment	3,783,357			4,271,905
Loans held-in-portfolio	3,903,867			4,348,703
UNITED STATES | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	16,416			15,638
Ending balance: loans collectively evaluated for impairment	174,629			221,323
Allowance for loan losses	191,045		201,978	236,961		248,912	274,775	337,794
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	185,715			296,153
Ending balance: loans collectively evaluated for impairment	5,524,379			5,466,304
Loans held-in-portfolio	5,710,094			5,762,457
Commercial Portfolio Segment Member
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	365,628		372,356	463,904		407,999	391,774	399,924
Loans held-in-portfolio:
Loans held-in-portfolio	11,952,993			12,486,069
Commercial Portfolio Segment Member | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	22,239			11,738
Ending balance: loans collectively evaluated for impairment	263,769			357,694
Allowance for loan losses	286,008			369,432
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	497,224			556,329
Ending balance: loans collectively evaluated for impairment	9,131,407			9,416,998
Loans held-in-portfolio	9,628,631			9,973,327
Commercial Portfolio Segment Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	15,294			27,086
Ending balance: loans collectively evaluated for impairment	64,326			67,386
Allowance for loan losses	79,620			94,472
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	120,510			76,798
Ending balance: loans collectively evaluated for impairment	2,203,852			2,435,944
Loans held-in-portfolio	2,324,362			2,512,742
Commercial Portfolio Segment Member | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	281,044			349,925
Loans held-in-portfolio:
Loans held-in-portfolio	8,508,177			8,983,324
Commercial Portfolio Segment Member | PUERTO RICO | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	21,246			10,407
Ending balance: loans collectively evaluated for impairment	180,178			245,046
Allowance for loan losses	201,424		203,846	255,453		245,747	227,133	256,643
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	404,375			403,089
Ending balance: loans collectively evaluated for impairment	5,779,440			6,067,493
Loans held-in-portfolio	6,183,815			6,470,582
Commercial Portfolio Segment Member | PUERTO RICO | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	15,294			27,086
Ending balance: loans collectively evaluated for impairment	64,326			67,386
Allowance for loan losses	79,620		75,592	94,472		63,475	47,829	0
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	120,510			76,798
Ending balance: loans collectively evaluated for impairment	2,203,852			2,435,944
Loans held-in-portfolio	2,324,362			2,512,742
Commercial Portfolio Segment Member | UNITED STATES | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	993			1,331
Ending balance: loans collectively evaluated for impairment	83,591			112,648
Allowance for loan losses	84,584		92,918	113,979		98,777	116,812	143,281
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	92,849			153,240
Ending balance: loans collectively evaluated for impairment	3,351,967			3,349,505
Loans held-in-portfolio	3,444,816			3,502,745
Commercial Real Estate Construction Financing Receivable Member
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	36,359		32,770	28,916		21,075	24,076	39,785
Loans held-in-portfolio:
Loans held-in-portfolio	651,554			786,765
Commercial Real Estate Construction Financing Receivable Member | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	191			289
Ending balance: loans collectively evaluated for impairment	8,945			8,192
Allowance for loan losses	9,136			8,481
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	47,897			91,710
Ending balance: loans collectively evaluated for impairment	210,556			148,229
Loans held-in-portfolio	258,453			239,939
Commercial Real Estate Construction Financing Receivable Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	27,223			20,435
Allowance for loan losses	27,223			20,435
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	393,101			546,826
Loans held-in-portfolio	393,101			546,826
Commercial Real Estate Construction Financing Receivable Member | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	34,622			26,285
Loans held-in-portfolio:
Loans held-in-portfolio	603,857			707,767
Commercial Real Estate Construction Financing Receivable Member | PUERTO RICO | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	191			289
Ending balance: loans collectively evaluated for impairment	7,208			5,561
Allowance for loan losses	7,399		7,464	5,850		5,007	7,073	16,074
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	35,757			49,747
Ending balance: loans collectively evaluated for impairment	174,999			111,194
Loans held-in-portfolio	210,756			160,941
Commercial Real Estate Construction Financing Receivable Member | PUERTO RICO | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	27,223			20,435
Allowance for loan losses	27,223		23,628	20,435		9,926	9,291	0
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	393,101			546,826
Loans held-in-portfolio	393,101			546,826
Commercial Real Estate Construction Financing Receivable Member | UNITED STATES | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	1,737			2,631
Allowance for loan losses	1,737		1,678	2,631		6,142	7,712	23,711
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	12,140			41,963
Ending balance: loans collectively evaluated for impairment	35,557			37,035
Loans held-in-portfolio	47,697			78,998
Mortgages
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	167,718		161,439	107,571		98,177	78,007	70,868
Loans held-in-portfolio:
Loans held-in-portfolio	7,129,273			6,691,414
Mortgages | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	62,823			29,063
Ending balance: loans collectively evaluated for impairment	92,009			73,198
Allowance for loan losses	154,832			102,261
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	560,441			382,880
Ending balance: loans collectively evaluated for impairment	5,461,981			5,135,580
Loans held-in-portfolio	6,022,422			5,518,460
Mortgages | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	12,886			5,310
Allowance for loan losses	12,886			5,310
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	1,106,851			1,172,954
Loans held-in-portfolio	1,106,851			1,172,954
Mortgages | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	137,976			77,632
Loans held-in-portfolio:
Loans held-in-portfolio	6,025,736			5,862,437
Mortgages | PUERTO RICO | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	47,523			14,944
Ending balance: loans collectively evaluated for impairment	77,567			57,378
Allowance for loan losses	125,090		120,339	72,322		65,430	55,140	42,029
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	506,723			333,346
Ending balance: loans collectively evaluated for impairment	4,412,162			4,356,137
Loans held-in-portfolio	4,918,885			4,689,483
Mortgages | PUERTO RICO | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	12,886			5,310
Allowance for loan losses	12,886		11,617	5,310		2,295	35	0
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	1,106,851			1,172,954
Loans held-in-portfolio	1,106,851			1,172,954
Mortgages | UNITED STATES | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	15,300			14,119
Ending balance: loans collectively evaluated for impairment	14,442			15,820
Allowance for loan losses	29,742		29,483	29,939		30,452	22,832	28,839
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	53,718			49,534
Ending balance: loans collectively evaluated for impairment	1,049,819			779,443
Loans held-in-portfolio	1,103,537			828,977
Legacy [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	39,871		44,011	46,228		65,553	73,545	76,405
Loans held-in-portfolio:
Loans held-in-portfolio	465,848			648,409
Legacy [Member] | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			57
Ending balance: loans collectively evaluated for impairment	39,871			46,171
Allowance for loan losses	39,871			46,228
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	24,276			48,890
Ending balance: loans collectively evaluated for impairment	441,572			599,519
Loans held-in-portfolio	465,848	[2]		648,409	[2]
Legacy [Member] | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	0			0
Allowance for loan losses	0			0
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	0			0
Loans held-in-portfolio	0			0
Legacy [Member] | UNITED STATES | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			57
Ending balance: loans collectively evaluated for impairment	39,871			46,171
Allowance for loan losses	39,871		44,011	46,228		65,553	73,545	76,405
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	24,276			48,890
Ending balance: loans collectively evaluated for impairment	441,572			599,519
Loans held-in-portfolio	465,848			648,409
Finance Leases Portfolio Segment Member
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	2,581		2,957	4,651		3,904	5,045	7,154
Loans held-in-portfolio:
Loans held-in-portfolio	538,014			548,706
Finance Leases Portfolio Segment Member | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	978			793
Ending balance: loans collectively evaluated for impairment	1,603			3,858
Allowance for loan losses	2,581			4,651
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	4,933			6,104
Ending balance: loans collectively evaluated for impairment	533,081			542,602
Loans held-in-portfolio	538,014			548,706
Finance Leases Portfolio Segment Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	0			0
Allowance for loan losses	0			0
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	0			0
Loans held-in-portfolio	0			0
Finance Leases Portfolio Segment Member | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	2,581			4,651
Loans held-in-portfolio:
Loans held-in-portfolio	538,014			548,706
Finance Leases Portfolio Segment Member | PUERTO RICO | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	978			793
Ending balance: loans collectively evaluated for impairment	1,603			3,858
Allowance for loan losses	2,581		2,957	4,651		3,904	5,045	7,154
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	4,933			6,104
Ending balance: loans collectively evaluated for impairment	533,081			542,602
Loans held-in-portfolio	538,014			548,706
Finance Leases Portfolio Segment Member | PUERTO RICO | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	0			0
Allowance for loan losses	0		0	0		0	0	0
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	0			0
Loans held-in-portfolio	0			0
Consumer Portfolio Segment Member
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	149,015		152,497	164,038		176,213	174,400	199,089
Loans held-in-portfolio:
Loans held-in-portfolio	3,920,038			3,789,936
Consumer Portfolio Segment Member | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	21,193			17,046
Ending balance: loans collectively evaluated for impairment	122,678			142,264
Allowance for loan losses	143,871			159,310
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	135,204			140,108
Ending balance: loans collectively evaluated for impairment	3,705,281			3,533,647
Loans held-in-portfolio	3,840,485			3,673,755
Consumer Portfolio Segment Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	5,144			4,728
Allowance for loan losses	5,144			4,728
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	79,553			116,181
Loans held-in-portfolio	79,553			116,181
Consumer Portfolio Segment Member | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Allowance for loan losses	113,904			119,854
Loans held-in-portfolio:
Loans held-in-portfolio	3,271,842			3,086,608
Consumer Portfolio Segment Member | PUERTO RICO | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	21,070			16,915
Ending balance: loans collectively evaluated for impairment	87,690			98,211
Allowance for loan losses	108,760		111,951	115,126		123,502	120,512	133,531
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	132,472			137,582
Ending balance: loans collectively evaluated for impairment	3,059,817			2,832,845
Loans held-in-portfolio	3,192,289			2,970,427
Consumer Portfolio Segment Member | PUERTO RICO | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	5,144			4,728
Allowance for loan losses	5,144		6,658	4,728		4,723	14	0
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	0			0
Ending balance: loans collectively evaluated for impairment	79,553			116,181
Loans held-in-portfolio	79,553			116,181
Consumer Portfolio Segment Member | UNITED STATES | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Ending balance: loans individually evaluated for impairment	123			131
Ending balance: loans collectively evaluated for impairment	34,988			44,053
Allowance for loan losses	35,111		33,888	44,184		47,988	53,874	65,558
Loans held-in-portfolio:
Ending balance: loans individually evaluated for impairment	2,732			2,526
Ending balance: loans collectively evaluated for impairment	645,464			700,802
Loans held-in-portfolio	$ 648,196			$ 703,328

[1] Non-covered loans held-in-portfolio at September 30, 2012 are net of $97 million in unearned income and exclude $337 million in loans held-for-sale. (December 31, 2011 - $101 million in unearned income and $363 million in loans held-for-sale.)

[2] The legacy portfolio is comprised of commercial loans, construction loans and lease financings related to certain lending products exited by the Corporation as part of restructuring efforts carried out in prior years at the BPNA reportable segment.