Allowance for loan losses ending balance and the loan balance by portfolio segments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011	Dec. 31, 2010
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	$ 803,264		$ 815,308		$ 736,505	$ 793,225
Loans held-in-portfolio:
Loans held-in-portfolio	19,082,387		24,951,299		25,406,339
Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	664,768		690,363
Ending balance: loans individually evaluated for impairment	76,056		58,986		17,892
Ending balance: loans collectively evaluated for impairment	588,712		631,377		709,454
Loans held-in-portfolio:
Loans held-in-portfolio	20,478,674	[1]	20,602,596	[1]
Financing Receivable, Individually Evaluated for Impairment	1,258,398		1,226,021		824,946
Financing Receivable, Collectively Evaluated for Impairment	19,220,276		19,376,575		19,851,843
Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	138,496		124,945		4,729,550
Ending balance: loans individually evaluated for impairment	32,489		27,086		0
Ending balance: loans collectively evaluated for impairment	106,007		97,859		9,159
Loans held-in-portfolio:
Loans held-in-portfolio	4,221,788		4,348,703
Financing Receivable, Individually Evaluated for Impairment	85,855		76,798		0
Financing Receivable, Collectively Evaluated for Impairment	4,135,933		4,271,905		4,729,550
PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	586,032		578,347		432,470
Loans held-in-portfolio:
Loans held-in-portfolio			19,188,842		18,991,341
PUERTO RICO | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	447,536		453,402		423,311	455,431
Ending balance: loans individually evaluated for impairment	59,455		43,348		15,095
Ending balance: loans collectively evaluated for impairment	388,081		410,054		408,216
Loans held-in-portfolio:
Loans held-in-portfolio			14,840,139		14,261,791
Financing Receivable, Individually Evaluated for Impairment	991,131		929,868		523,501
Financing Receivable, Collectively Evaluated for Impairment	13,869,468		13,910,271		13,738,290
PUERTO RICO | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	138,496		124,945		9,159	0
Ending balance: loans individually evaluated for impairment	32,489		27,086		0
Ending balance: loans collectively evaluated for impairment	106,007		97,859		9,159
Loans held-in-portfolio:
Loans held-in-portfolio	4,221,788		4,348,703		4,729,550
Financing Receivable, Individually Evaluated for Impairment	85,855		76,798		0
Financing Receivable, Collectively Evaluated for Impairment	4,135,933		4,271,905		4,729,550
UNITED STATES | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	217,232		236,961		304,035	337,794
Ending balance: loans individually evaluated for impairment	16,601		15,638		2,797
Ending balance: loans collectively evaluated for impairment	200,631		221,323		301,238
Loans held-in-portfolio:
Loans held-in-portfolio	5,618,075		5,762,457		6,414,998
Financing Receivable, Individually Evaluated for Impairment	267,267		296,153		301,445
Financing Receivable, Collectively Evaluated for Impairment	5,350,808		5,466,304		6,113,553
Commercial Portfolio Segment Member
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	403,649		463,904		349,226	399,924
Loans held-in-portfolio:
Loans held-in-portfolio	12,299,943		12,486,069		13,110,415
Commercial Portfolio Segment Member | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	313,579		369,432		347,291
Ending balance: loans individually evaluated for impairment	12,998		11,738		9,726
Ending balance: loans collectively evaluated for impairment	300,581		357,694		337,565
Loans held-in-portfolio:
Loans held-in-portfolio	9,868,242		9,973,327		10,401,285
Financing Receivable, Individually Evaluated for Impairment	552,152		556,329		449,079
Financing Receivable, Collectively Evaluated for Impairment	9,316,090		9,416,998		9,952,206
Commercial Portfolio Segment Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	90,070		94,472		1,935
Ending balance: loans individually evaluated for impairment	32,489		27,086		0
Ending balance: loans collectively evaluated for impairment	57,581		67,386		1,935
Loans held-in-portfolio:
Loans held-in-portfolio	2,431,701		2,512,742		2,709,130
Financing Receivable, Individually Evaluated for Impairment	85,855		76,798		0
Financing Receivable, Collectively Evaluated for Impairment	2,345,846		2,435,944		2,709,130
Commercial Portfolio Segment Member | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	311,399		349,925		221,149
Loans held-in-portfolio:
Loans held-in-portfolio	8,861,370		8,983,324		9,371,716
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
Balance at end of period	221,329		255,453		219,214	256,643
Ending balance: loans individually evaluated for impairment	11,115		10,407		8,212
Ending balance: loans collectively evaluated for impairment	210,214		245,046		211,002
Loans held-in-portfolio:
Loans held-in-portfolio	6,429,669		6,470,582		6,662,586
Financing Receivable, Individually Evaluated for Impairment	402,097		403,089		325,075
Financing Receivable, Collectively Evaluated for Impairment	6,027,572		6,067,493		6,337,511
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
Balance at end of period	90,070		94,472		1,935	0
Ending balance: loans individually evaluated for impairment	32,489		27,086		0
Ending balance: loans collectively evaluated for impairment	57,581		67,386		1,935
Loans held-in-portfolio:
Loans held-in-portfolio	2,431,701		2,512,742		2,709,130
Financing Receivable, Individually Evaluated for Impairment	85,855		76,798		0
Financing Receivable, Collectively Evaluated for Impairment	2,345,846		2,435,944		2,709,130
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
Balance at end of period	92,250		113,979		128,077	143,281
Ending balance: loans individually evaluated for impairment	1,883		1,331		1,514
Ending balance: loans collectively evaluated for impairment	90,367		112,648		126,563
Loans held-in-portfolio:
Loans held-in-portfolio	3,438,573		3,502,745		3,738,699
Financing Receivable, Individually Evaluated for Impairment	150,055		153,240		124,004
Financing Receivable, Collectively Evaluated for Impairment	3,288,518		3,349,505		3,614,695
Commercial Real Estate Construction Financing Receivable Member
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	38,860		28,916		40,511	39,785
Loans held-in-portfolio:
Loans held-in-portfolio			786,765		911,070
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
Balance at end of period	9,133		8,481
Ending balance: loans individually evaluated for impairment	1,013		289		0
Ending balance: loans collectively evaluated for impairment	8,120		8,192		33,577
Loans held-in-portfolio:
Loans held-in-portfolio	236,579		239,939
Financing Receivable, Individually Evaluated for Impairment	64,149		91,710		124,824
Financing Receivable, Collectively Evaluated for Impairment	172,430		148,229		165,059
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
Balance at end of period	29,727		20,435		621,187
Ending balance: loans individually evaluated for impairment	0		0		0
Ending balance: loans collectively evaluated for impairment	29,727		20,435		6,934
Loans held-in-portfolio:
Loans held-in-portfolio	532,433		546,826
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	532,433		546,826		621,187
Commercial Real Estate Construction Financing Receivable Member | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	36,398		26,285		18,372
Loans held-in-portfolio:
Loans held-in-portfolio	708,201		707,767		770,476
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
Balance at end of period	6,671		5,850		11,438	16,074
Ending balance: loans individually evaluated for impairment	1,013		289		0
Ending balance: loans collectively evaluated for impairment	5,658		5,561		11,438
Loans held-in-portfolio:
Loans held-in-portfolio			160,941		149,289
Financing Receivable, Individually Evaluated for Impairment	51,023		49,747		56,607
Financing Receivable, Collectively Evaluated for Impairment	124,745		111,194		92,682
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
Balance at end of period	29,727		20,435		6,934	0
Ending balance: loans individually evaluated for impairment	0		0		0
Ending balance: loans collectively evaluated for impairment	29,727		20,435		6,934
Loans held-in-portfolio:
Loans held-in-portfolio	532,433		546,826		621,187
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	532,433		546,826		621,187
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
Balance at end of period	2,462		2,631		22,139	23,711
Ending balance: loans individually evaluated for impairment	0		0		0
Ending balance: loans collectively evaluated for impairment	2,462		2,631		22,139
Loans held-in-portfolio:
Loans held-in-portfolio	60,811		78,998		140,594
Financing Receivable, Individually Evaluated for Impairment	13,126		41,963		68,217
Financing Receivable, Collectively Evaluated for Impairment	47,685		37,035		72,377
Mortgages
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	135,996		107,571		80,169	70,868
Loans held-in-portfolio:
Loans held-in-portfolio			6,691,414		6,143,158
Mortgages | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	125,479		102,261
Ending balance: loans individually evaluated for impairment	40,946		29,063		8,166
Ending balance: loans collectively evaluated for impairment	84,533		73,198		71,944
Loans held-in-portfolio:
Loans held-in-portfolio	5,591,745		5,518,460
Financing Receivable, Individually Evaluated for Impairment	450,754		382,880		147,026
Financing Receivable, Collectively Evaluated for Impairment	5,140,991		5,135,580		4,748,656
Mortgages | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	10,517		5,310		1,247,476
Ending balance: loans individually evaluated for impairment	0		0		0
Ending balance: loans collectively evaluated for impairment	10,517		5,310		59
Loans held-in-portfolio:
Loans held-in-portfolio	1,150,996		1,172,954
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	1,150,996		1,172,954		1,247,476
Mortgages | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	107,024		77,632		55,926
Loans held-in-portfolio:
Loans held-in-portfolio	5,911,341		5,862,437		5,278,656
Mortgages | PUERTO RICO | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	96,507		72,322		55,867	42,029
Ending balance: loans individually evaluated for impairment	27,096		14,944		6,883
Ending balance: loans collectively evaluated for impairment	69,411		57,378		48,984
Loans held-in-portfolio:
Loans held-in-portfolio			4,689,483		4,031,180
Financing Receivable, Individually Evaluated for Impairment	396,854		333,346		141,819
Financing Receivable, Collectively Evaluated for Impairment	4,363,491		4,356,137		3,889,361
Mortgages | PUERTO RICO | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	10,517		5,310		59	0
Ending balance: loans individually evaluated for impairment	0		0		0
Ending balance: loans collectively evaluated for impairment	10,517		5,310		59
Loans held-in-portfolio:
Loans held-in-portfolio	1,150,996		1,172,954		1,247,476
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	1,150,996		1,172,954		1,247,476
Mortgages | UNITED STATES | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	28,972		29,939		24,243	28,839
Ending balance: loans individually evaluated for impairment	13,850		14,119		1,283
Ending balance: loans collectively evaluated for impairment	15,122		15,820		22,960
Loans held-in-portfolio:
Loans held-in-portfolio	831,400		828,977		864,502
Financing Receivable, Individually Evaluated for Impairment	53,900		49,534		5,207
Financing Receivable, Collectively Evaluated for Impairment	777,500		779,443		859,295
Legacy [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	54,725		46,228		69,911	76,405
Loans held-in-portfolio:
Loans held-in-portfolio			648,409		898,772
Legacy [Member] | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	54,725		46,228
Ending balance: loans individually evaluated for impairment	765		57		0
Ending balance: loans collectively evaluated for impairment	53,960		46,171		69,911
Loans held-in-portfolio:
Loans held-in-portfolio	603,874	[2]	648,409	[2]
Financing Receivable, Individually Evaluated for Impairment	47,731		48,890		104,017
Financing Receivable, Collectively Evaluated for Impairment	556,143		599,519		794,755
Legacy [Member] | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	0		0		0
Ending balance: loans individually evaluated for impairment	0		0		0
Ending balance: loans collectively evaluated for impairment	0		0		0
Loans held-in-portfolio:
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	0		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
Balance at end of period	54,725		46,228		69,911	76,405
Ending balance: loans individually evaluated for impairment	765		57		0
Ending balance: loans collectively evaluated for impairment	53,960		46,171		69,911
Loans held-in-portfolio:
Loans held-in-portfolio	603,874		648,409		898,772
Financing Receivable, Individually Evaluated for Impairment	47,731		48,890		104,017
Financing Receivable, Collectively Evaluated for Impairment	556,143		599,519		794,755
Finance Leases Portfolio Segment Member
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	4,967		4,651		6,608	7,154
Loans held-in-portfolio:
Loans held-in-portfolio			548,706		565,881
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
Balance at end of period	4,967		4,651
Ending balance: loans individually evaluated for impairment	1,344		793		0
Ending balance: loans collectively evaluated for impairment	3,623		3,858		6,608
Loans held-in-portfolio:
Loans held-in-portfolio	543,314		548,706
Financing Receivable, Individually Evaluated for Impairment	5,412		6,104		0
Financing Receivable, Collectively Evaluated for Impairment	537,902		542,602		565,881
Finance Leases Portfolio Segment Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	0		0		0
Ending balance: loans individually evaluated for impairment	0		0		0
Ending balance: loans collectively evaluated for impairment	0		0		0
Loans held-in-portfolio:
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	0		0		0
Finance Leases Portfolio Segment Member | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	4,967		4,651		6,608
Loans held-in-portfolio:
Loans held-in-portfolio	543,314		548,706		565,881
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
Balance at end of period	4,967		4,651		6,608	7,154
Ending balance: loans individually evaluated for impairment	1,344		793		0
Ending balance: loans collectively evaluated for impairment	3,623		3,858		6,608
Loans held-in-portfolio:
Loans held-in-portfolio			548,706		565,881
Financing Receivable, Individually Evaluated for Impairment	5,412		6,104		0
Financing Receivable, Collectively Evaluated for Impairment	537,902		542,602		565,881
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
Balance at end of period	0		0		0	0
Ending balance: loans individually evaluated for impairment			0		0
Ending balance: loans collectively evaluated for impairment	0		0		0
Loans held-in-portfolio:
Loans held-in-portfolio	0		0		0
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	0		0		0
Consumer Portfolio Segment Member
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	165,067		164,038		190,080	199,089
Loans held-in-portfolio:
Loans held-in-portfolio	3,741,578		3,789,936		3,777,043
Consumer Portfolio Segment Member | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	156,885		159,310		189,849
Ending balance: loans individually evaluated for impairment	18,990		17,046		0
Ending balance: loans collectively evaluated for impairment	137,895		142,264		189,849
Loans held-in-portfolio:
Loans held-in-portfolio	3,634,920		3,673,755		3,625,286
Financing Receivable, Individually Evaluated for Impairment	138,200		140,108		0
Financing Receivable, Collectively Evaluated for Impairment	3,496,720		3,533,647		3,625,286
Consumer Portfolio Segment Member | Covered Under Loss Sharing Agreements With F D I C [Member]
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	8,182		4,728		231
Ending balance: loans individually evaluated for impairment	0		0		0
Ending balance: loans collectively evaluated for impairment	8,182		4,728		231
Loans held-in-portfolio:
Loans held-in-portfolio	106,658		116,181		151,757
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	106,658		116,181		151,757
Consumer Portfolio Segment Member | PUERTO RICO
Financing Receivable Allowance For Credit Losses Roll Forward
Balance at end of period	126,244		119,854		130,415
Loans held-in-portfolio:
Loans held-in-portfolio	3,058,161		3,086,608		3,004,612
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
Balance at end of period	118,062		115,126		130,184	133,531
Ending balance: loans individually evaluated for impairment	18,887		16,915		0
Ending balance: loans collectively evaluated for impairment	99,175		98,211		130,184
Loans held-in-portfolio:
Loans held-in-portfolio	2,951,503		2,970,427		2,852,855
Financing Receivable, Individually Evaluated for Impairment	135,745		137,582		0
Financing Receivable, Collectively Evaluated for Impairment	2,815,758		2,832,845		2,852,855
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
Balance at end of period	8,182		4,728		231	0
Ending balance: loans individually evaluated for impairment	0				0
Ending balance: loans collectively evaluated for impairment	8,182		4,728		231
Loans held-in-portfolio:
Loans held-in-portfolio	106,658		116,181		151,757
Financing Receivable, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Collectively Evaluated for Impairment	106,658		116,181		151,757
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
Balance at end of period	38,823		44,184		59,665	65,558
Ending balance: loans individually evaluated for impairment	103		131		0
Ending balance: loans collectively evaluated for impairment	38,720		44,053		59,665
Loans held-in-portfolio:
Loans held-in-portfolio	683,417		703,328		772,431
Financing Receivable, Individually Evaluated for Impairment	2,455		2,526		0
Financing Receivable, Collectively Evaluated for Impairment	$ 680,962		$ 700,802		$ 772,431

[1] Non-covered loans held-in-portfolio at March 31, 2012 are net of $99 million in unearned income and exclude $362 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.