Carrying or notional amounts and estimated fair values for financial instruments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011	Dec. 31, 2010
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	$ 477,342		$ 535,282		$ 567,141	$ 452,373
Money market investments	925,663		1,376,174
Marketable Securities, Alternative [Abstract]
Servicing Asset At Fair Value Amount	158,367		151,323		157,226	166,907
Derivative Fair Value Of Derivative Asset	49,879		61,886
Deposits, by Type [Abstract]
Time Deposits	8,726,196		10,710,040
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase	1,944,564		2,141,097
Notes Payable [Abstract]
Other Notes Payable	24,373		25,070
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
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	491,662	[1]	470,037	[1]
Fair Value, Inputs, Level 1 [Member]
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	477,342
Money market investments	611,796
Trading account securities	0	[2]
Available For Sale Securities Fair Value Disclosure	3,941	[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
Letters 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] | Puerto Rico States And Political Subdivisions Debt Securities [Member]
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 Securities [Member]
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	313,867
Trading account securities	209,323	[2]
Available For Sale Securities Fair Value Disclosure	5,109,217	[2]
Held To Maturity Securities Fair Value Disclosure	1,500
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	117,550
Federal Reserve Bank Stock	79,718
Trust Preferred Securities	13,197
Other Investments	0
Total other investment securities	210,465
Loans held-for-sale	9,387
FDIC loss share asset	0
Servicing Asset At Fair Value Amount	0
Derivative Fair Value Of Derivative Asset	49,881
Deposits, by Type [Abstract]
Demand Deposit Accounts	17,593,304
Time Deposits	8,808,199
Deposits	26,401,503
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Federal Funds Purchased	0
Securities Sold under Agreements to Repurchase	1,313,558
Assets sold under agreements to repurchase	2,041,401
Other short-term borrowings	1,206,200	[3]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term	664,250
Medium-term Notes	310,143
Other Notes Payable	0
Notes payable	1,344,666
Derivative Financial Instruments Liabilities Fair Value Disclosure	56,629
Business Acquisition, Contingent Consideration, at Fair Value	0
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	0
Letters 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	727,844
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	370,273
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] | Puerto Rico States And Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	0
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 Securities [Member]
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	17,593	[2]
Available For Sale Securities Fair Value Disclosure	7,143	[2]
Held To Maturity Securities Fair Value Disclosure	122,602
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	0
Federal Reserve Bank Stock	0
Trust Preferred Securities	1,000
Other Investments	3,675
Total other investment securities	4,675
Loans held-for-sale	342,287
FDIC loss share asset	1,450,671
Servicing Asset At Fair Value Amount	158,367
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	3,903
Other Notes Payable	24,373
Notes payable	756,372
Derivative Financial Instruments Liabilities Fair Value Disclosure	0
Business Acquisition, Contingent Consideration, at Fair Value	103,688
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	1,633
Letters of credit Fair Value Disclosure	2,285
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	728,096
Fair Value, Inputs, Level 3 [Member] | Puerto Rico States And Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	97,424
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	153
Fair Value, Inputs, Level 3 [Member] | Other Securities [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	25,025
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	16,926,290
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	4,380,019
Carrying (Reported) Amount, Fair Value Disclosure
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	477,342		535,282
Money market investments	925,663		1,376,174
Trading account securities	226,916	[2]	436,330	[2]
Available For Sale Securities Fair Value Disclosure	5,120,301	[2]	5,009,823	[2]
Held To Maturity Securities Fair Value Disclosure	122,072		125,383
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	117,550		84,133
Federal Reserve Bank Stock	79,718		79,648
Trust Preferred Securities	14,197		14,197
Other Investments	1,924		1,902
Total other investment securities	213,389		179,880
Loans held-for-sale	337,049		363,093
FDIC loss share asset	1,559,057		1,915,128
Servicing Asset At Fair Value Amount	158,367		151,323
Derivative Fair Value Of Derivative Asset	49,881		61,887
Deposits, by Type [Abstract]
Demand Deposit Accounts	17,593,304		17,232,087
Time Deposits	8,726,195		10,710,040
Deposits	26,319,499		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	1,306,374		1,102,907
Assets sold under agreements to repurchase	1,944,564		2,141,097
Other short-term borrowings	1,206,200	[3]	296,200	[3]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term	631,898		642,568
Medium-term Notes	278,644		278,897
Other Notes Payable	24,373		25,070
Notes payable	1,866,377		1,856,372
Derivative Financial Instruments Liabilities Fair Value Disclosure	56,629		66,700
Business Acquisition, Contingent Consideration, at Fair Value	103,688		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	638,190		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	491,662		470,037
Carrying (Reported) Amount, Fair Value Disclosure | Puerto Rico States And Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	95,425		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	147		160
Carrying (Reported) Amount, Fair Value Disclosure | Other Securities [Member]
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	20,117,554		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	3,778,994		4,223,758
Estimate of Fair Value, Fair Value Disclosure
Assets Fair Value Disclosure Abstract
Cash And Due From Banks	477,342		535,282
Money market investments	925,663		1,376,174
Trading account securities	226,916	[2]	436,330	[2]
Available For Sale Securities Fair Value Disclosure	5,120,301	[2]	5,009,823	[2]
Held To Maturity Securities Fair Value Disclosure	124,102		125,254
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock	117,550		84,133
Federal Reserve Bank Stock	79,718		79,648
Trust Preferred Securities	14,197		14,197
Other Investments	3,675		3,605
Total other investment securities	215,140		181,583
Loans held-for-sale	351,675		390,783
FDIC loss share asset	1,450,671		1,755,295
Servicing Asset At Fair Value Amount	158,367		151,323
Derivative Fair Value Of Derivative Asset	49,881		61,887
Deposits, by Type [Abstract]
Demand Deposit Accounts	17,593,304		17,232,087
Time Deposits	8,808,199		10,825,256
Deposits	26,401,503		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	1,313,558		1,107,314
Assets sold under agreements to repurchase	2,041,401		2,273,802
Other short-term borrowings	1,206,200	[3]	296,200	[3]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term	664,250		673,505
Medium-term Notes	314,045		282,898
Other Notes Payable	24,373		25,070
Notes payable	2,101,038		1,722,831
Derivative Financial Instruments Liabilities Fair Value Disclosure	56,629		66,700
Business Acquisition, Contingent Consideration, at Fair Value	103,688		99,762
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	1,633		2,062
Letters of credit Fair Value Disclosure	2,285		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	727,844		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	370,273		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	728,096		457,120
Estimate of Fair Value, Fair Value Disclosure | Puerto Rico States And Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	97,424		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	153		151
Estimate of Fair Value, Fair Value Disclosure | Other Securities [Member]
Assets Fair Value Disclosure Abstract
Held To Maturity Securities Fair Value Disclosure	26,525		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	16,926,290		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	4,380,019		4,663,327
Notional Amount [Member]
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit	7,327,865		6,695,956
Letters of credit Fair Value Disclosure	$ 154,745		$ 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 September 30, 2012 and December 31, 2011.

[2] Refer to Note 22 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.