Carrying or notional amounts and estimated fair values for financial instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011		Dec. 31, 2010
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	$ 472,806		$ 535,282		$ 464,555		$ 452,373
Money market investments	1,304,263		1,376,174		961,565
Marketable Securities, Alternative [Abstract]
Servicing Asset At Fair Value Amount	156,331		151,323		167,416		166,907
Derivative Fair Value Of Derivative Asset	58,604		61,886		65,169
Deposits, by Type [Abstract]
Time Deposits	9,923,591		10,710,040		11,017,332
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase	2,113,557		2,141,097		2,642,800
Notes Payable [Abstract]
Other Notes Payable	24,896		25,070		25,206
Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	439,800		439,800		439,800
Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	476,957	[1]	470,037	[1]	450,872	[1]
Fair Value, Inputs, Level 1 [Member]
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	472,806
Money market investments	0
Trading account securities	0	[2]
Available For Sale Securities Fair Value Disclosure	3,846	[2]
Held To Maturity Securities Fair Value Disclosure	0
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	0
Federal Reserve Bank Stock	0
Trust Preferred Securities	0
Other Investments	0
Total other investment securities	0
Loans held-for-sale	0
FDIC loss share asset	0
Servicing Asset At Fair Value Amount	0
Derivative Fair Value Of Derivative Asset	0
Deposits, by Type [Abstract]
Demand Deposit Accounts	0
Time Deposits	0
Deposits	0
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Federal Funds Purchased	0
Securities Sold under Agreements to Repurchase	0
Assets sold under agreements to repurchase	0
Other short-term borrowings	0	[3]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term	0
Medium-term Notes	0
Other Notes Payable	0
Notes payable	0
Derivative Financial Instruments Liabilities Fair Value Disclosure	0
Business Acquisition, Contingent Consideration, at Fair Value	0
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	0
Lines Of Credit Fair Value Disclosure	0
Fair Value, Inputs, Level 1 [Member] | Structured Finance [Member]
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase	0
Fair Value, Inputs, Level 1 [Member] | Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	0
Fair Value, Inputs, Level 1 [Member] | Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	0
Fair Value, Inputs, Level 1 [Member] | Obligations of Puerto Rico, States and political subdivisions
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	0
Fair Value, Inputs, Level 1 [Member] | Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	0
Fair Value, Inputs, Level 1 [Member] | Other
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member]
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	0
Money market investments	1,304,263
Trading account securities	381,105	[2]
Available For Sale Securities Fair Value Disclosure	5,127,544	[2]
Held To Maturity Securities Fair Value Disclosure	2,900
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	100,240
Federal Reserve Bank Stock	79,369
Trust Preferred Securities	(13,197)
Other Investments	0
Total other investment securities	192,806
Loans held-for-sale	3,229
FDIC loss share asset	0
Servicing Asset At Fair Value Amount	0
Derivative Fair Value Of Derivative Asset	58,691
Deposits, by Type [Abstract]
Demand Deposit Accounts	17,274,145
Time Deposits	10,015,038
Deposits	27,289,183
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Federal Funds Purchased	0
Securities Sold under Agreements to Repurchase	1,131,082
Assets sold under agreements to repurchase	2,233,418
Other short-term borrowings	751,200	[3]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term	654,941
Medium-term Notes	283,965
Other Notes Payable	0
Notes payable	1,282,182
Derivative Financial Instruments Liabilities Fair Value Disclosure	62,717
Business Acquisition, Contingent Consideration, at Fair Value	0
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	0
Lines Of Credit Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member] | Structured Finance [Member]
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase	1,102,336
Fair Value, Inputs, Level 2 [Member] | Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	343,276
Fair Value, Inputs, Level 2 [Member] | Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	0
Fair Value, Inputs, Level 2 [Member] | Obligations of Puerto Rico, States and political subdivisions
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	1,400
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member] | Other
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	1,500
Fair Value, Inputs, Level 3 [Member]
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	0
Money market investments	0
Trading account securities	23,101	[2]
Available For Sale Securities Fair Value Disclosure	7,226	[2]
Held To Maturity Securities Fair Value Disclosure	121,929
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	0
Federal Reserve Bank Stock	0
Trust Preferred Securities	(1,000)
Other Investments	3,566
Total other investment securities	4,566
Loans held-for-sale	375,794
FDIC loss share asset	1,734,507
Servicing Asset At Fair Value Amount	156,331
Derivative Fair Value Of Derivative Asset	0
Deposits, by Type [Abstract]
Demand Deposit Accounts	0
Time Deposits	0
Deposits	0
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Federal Funds Purchased	0
Securities Sold under Agreements to Repurchase	0
Assets sold under agreements to repurchase	0
Other short-term borrowings	0	[3]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term	0
Medium-term Notes	4,053
Other Notes Payable	24,896
Notes payable	758,300
Derivative Financial Instruments Liabilities Fair Value Disclosure	0
Business Acquisition, Contingent Consideration, at Fair Value	100,834
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	1,796
Lines Of Credit Fair Value Disclosure	3,450
Fair Value, Inputs, Level 3 [Member] | Structured Finance [Member]
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase	0
Fair Value, Inputs, Level 3 [Member] | Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	0
Fair Value, Inputs, Level 3 [Member] | Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	729,351
Fair Value, Inputs, Level 3 [Member] | Obligations of Puerto Rico, States and political subdivisions
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	96,739
Fair Value, Inputs, Level 3 [Member] | Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	161
Fair Value, Inputs, Level 3 [Member] | Other
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	25,029
Non Covered Under Loss Sharing Agreements With F D I C [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	0
Non Covered Under Loss Sharing Agreements With F D I C [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	0
Non Covered Under Loss Sharing Agreements With F D I C [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	16,749,026
Covered Under Loss Sharing Agreements With F D I C [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	0
Covered Under Loss Sharing Agreements With F D I C [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	0
Covered Under Loss Sharing Agreements With F D I C [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	4,665,129
Carrying (Reported) Amount, Fair Value Disclosure
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	472,806		535,282
Money market investments	1,304,263		1,376,174
Trading account securities	404,206	[2]	436,330	[2]
Available For Sale Securities Fair Value Disclosure	5,138,616	[2]	5,009,823	[2]
Held To Maturity Securities Fair Value Disclosure	124,372		125,383
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	100,240		84,133
Federal Reserve Bank Stock	79,369		79,648
Trust Preferred Securities	(14,197)		(14,197)
Other Investments	1,902		1,902
Total other investment securities	195,708		179,880
Loans held-for-sale	361,596		363,093
FDIC loss share asset	1,880,357		1,915,128
Servicing Asset At Fair Value Amount	156,331		151,323
Derivative Fair Value Of Derivative Asset	58,691		61,887
Deposits, by Type [Abstract]
Demand Deposit Accounts	17,274,145		17,232,087
Time Deposits	9,923,591		10,710,040
Deposits	27,197,736		27,942,127
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Federal Funds Purchased	0		0
Securities Sold under Agreements to Repurchase	1,125,367		1,102,907
Assets sold under agreements to repurchase	2,113,557		2,141,097
Other short-term borrowings	751,200	[3]	296,200	[3]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term	623,286		642,568
Medium-term Notes	278,815		278,897
Other Notes Payable	24,896		25,070
Notes payable	1,843,754		1,856,372
Derivative Financial Instruments Liabilities Fair Value Disclosure	62,717		66,700
Business Acquisition, Contingent Consideration, at Fair Value	100,834		99,762
Carrying (Reported) Amount, Fair Value Disclosure | Structured Finance [Member]
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase	988,190		1,038,190
Carrying (Reported) Amount, Fair Value Disclosure | Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	439,800		439,800
Carrying (Reported) Amount, Fair Value Disclosure | Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	476,957		470,037
Carrying (Reported) Amount, Fair Value Disclosure | Obligations of Puerto Rico, States and political subdivisions
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	97,717		98,973
Carrying (Reported) Amount, Fair Value Disclosure | Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	155		160
Carrying (Reported) Amount, Fair Value Disclosure | Other
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	26,500		26,250
Carrying (Reported) Amount, Fair Value Disclosure | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	19,813,906		19,912,233
Carrying (Reported) Amount, Fair Value Disclosure | Covered Under Loss Sharing Agreements With F D I C [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	4,083,292		4,223,758
Estimate of Fair Value, Fair Value Disclosure
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	472,806		535,282
Money market investments	1,304,263		1,376,174
Trading account securities	404,206	[2]	436,330	[2]
Available For Sale Securities Fair Value Disclosure	5,138,616	[2]	5,009,823	[2]
Held To Maturity Securities Fair Value Disclosure	124,829		125,254
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	100,240		84,133
Federal Reserve Bank Stock	79,369		79,648
Trust Preferred Securities	(14,197)		(14,197)
Other Investments	3,566		3,605
Total other investment securities	197,372		181,583
Loans held-for-sale	379,023		390,783
FDIC loss share asset	1,734,507		1,755,295
Servicing Asset At Fair Value Amount	156,331		151,323
Derivative Fair Value Of Derivative Asset	58,691		61,887
Deposits, by Type [Abstract]
Demand Deposit Accounts	17,274,145		17,232,087
Time Deposits	10,015,038		10,825,256
Deposits	27,289,183		28,057,343
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Federal Funds Purchased	0		0
Securities Sold under Agreements to Repurchase	1,131,082		1,107,314
Assets sold under agreements to repurchase	2,233,418		2,273,802
Other short-term borrowings	751,200	[3]	296,200	[3]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term	654,941		673,505
Medium-term Notes	288,018		282,898
Other Notes Payable	24,896		25,070
Notes payable	2,040,482		1,722,831
Derivative Financial Instruments Liabilities Fair Value Disclosure	62,717		66,700
Business Acquisition, Contingent Consideration, at Fair Value	100,834		99,762
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	1,796		2,062
Lines Of Credit Fair Value Disclosure	3,450		2,339
Estimate of Fair Value, Fair Value Disclosure | Structured Finance [Member]
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase	1,102,336		1,166,488
Estimate of Fair Value, Fair Value Disclosure | Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	343,276		284,238
Estimate of Fair Value, Fair Value Disclosure | Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]
Notes Payable [Abstract]
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust	729,351		457,120
Estimate of Fair Value, Fair Value Disclosure | Obligations of Puerto Rico, States and political subdivisions
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	98,139		98,770
Estimate of Fair Value, Fair Value Disclosure | Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	161		151
Estimate of Fair Value, Fair Value Disclosure | Other
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	26,529		26,333
Estimate of Fair Value, Fair Value Disclosure | Non Covered Under Loss Sharing Agreements With F D I C [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	16,749,026		16,753,889
Estimate of Fair Value, Fair Value Disclosure | Covered Under Loss Sharing Agreements With F D I C [Member]
Marketable Securities, Alternative [Abstract]
Loans held-in-portfolio, net	4,665,129		4,663,327
Notional Amount [Member]
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	6,821,833		6,231,213
Lines Of Credit Fair Value Disclosure	$ 143,485		$ 136,341

[1] The debentures are perpetual and may be redeemed by the Corporation at any time, subject to the consent of the Board of Governors of the Federal Reserve System. The discount on the debentures is being amortized over an estimated 30-year term that started in August 2009. The effective interest rate, including the discount accretion, was approximately 16% at March 31, 2012 and 2011.

[2] Refer to Note 21 to the consolidated financial statements for the fair value by class of financial asset and its hierarchy level.

[3] Refer to Note 14 to the consolidated financial statements for the composition of short-term borrowings.