Carrying or notional amounts and estimated fair values for financial instruments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2014 Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Dec. 31, 2013 Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Sep. 30, 2014 Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]		Dec. 31, 2013 Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]		Sep. 30, 2014 Fixed Rate 700 Percent Notes Due July 2019 [Member]	Jun. 30, 2014 Fixed Rate 700 Percent Notes Due July 2019 [Member]	Dec. 31, 2013 Fixed Rate 700 Percent Notes Due July 2019 [Member]	Sep. 30, 2014 Puerto Rico States And Political Subdivisions Debt Securities [Member]	Dec. 31, 2013 Puerto Rico States And Political Subdivisions Debt Securities [Member]	Sep. 30, 2014 Collateralized Mortgage Obligations Issued By Private Enterprise [Member]	Dec. 31, 2013 Collateralized Mortgage Obligations Issued By Private Enterprise [Member]	Sep. 30, 2014 Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Dec. 31, 2013 Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Sep. 30, 2014 Other Securities [Member]	Dec. 31, 2013 Other Securities [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2013 Fair Value, Inputs, Level 1 [Member]		Sep. 30, 2014 Fair Value, Inputs, Level 1 [Member] Structured Finance [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 1 [Member] Structured Finance [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 1 [Member] Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 1 [Member] Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Sep. 30, 2014 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]	Dec. 31, 2013 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]	Sep. 30, 2014 Fair Value, Inputs, Level 1 [Member] Puerto Rico States And Political Subdivisions Debt Securities [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 1 [Member] Puerto Rico States And Political Subdivisions Debt Securities [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 1 [Member] Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 1 [Member] Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 1 [Member] Other Securities [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 1 [Member] Other Securities [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member]		Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member] Structured Finance [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] Structured Finance [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member] Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Sep. 30, 2014 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]	Dec. 31, 2013 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]	Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member] Puerto Rico States And Political Subdivisions Debt Securities [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] Puerto Rico States And Political Subdivisions Debt Securities [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member] Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member] Other Securities [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] Other Securities [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member]		Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member] Structured Finance [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Structured Finance [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member] Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Sep. 30, 2014 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]	Dec. 31, 2013 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]	Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member] Puerto Rico States And Political Subdivisions Debt Securities [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Puerto Rico States And Political Subdivisions Debt Securities [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member] Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member] Other Securities [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Other Securities [Member]	Sep. 30, 2014 Non Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2013 Non Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2014 Non Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2013 Non Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2014 Non Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2013 Non Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2014 Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2013 Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2014 Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2013 Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2014 Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2013 Covered Under Loss Sharing Agreements With F D I C [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2014 Carrying (Reported) Amount, Fair Value Disclosure		Dec. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure		Sep. 30, 2014 Carrying (Reported) Amount, Fair Value Disclosure Structured Finance [Member]	Dec. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure Structured Finance [Member]	Sep. 30, 2014 Carrying (Reported) Amount, Fair Value Disclosure Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Dec. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Sep. 30, 2014 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]	Dec. 31, 2013 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]	Sep. 30, 2014 Carrying (Reported) Amount, Fair Value Disclosure Puerto Rico States And Political Subdivisions Debt Securities [Member]	Dec. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure Puerto Rico States And Political Subdivisions Debt Securities [Member]	Sep. 30, 2014 Carrying (Reported) Amount, Fair Value Disclosure Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Dec. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Sep. 30, 2014 Carrying (Reported) Amount, Fair Value Disclosure Other Securities [Member]	Dec. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure Other Securities [Member]	Sep. 30, 2014 Carrying (Reported) Amount, Fair Value Disclosure Non Covered Under Loss Sharing Agreements With F D I C [Member]	Dec. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure Non Covered Under Loss Sharing Agreements With F D I C [Member]	Sep. 30, 2014 Carrying (Reported) Amount, Fair Value Disclosure Covered Under Loss Sharing Agreements With F D I C [Member]	Dec. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure Covered Under Loss Sharing Agreements With F D I C [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure		Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure		Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Structured Finance [Member]	Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure Structured Finance [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure Fixed Rate 6125 To 8327 Percent Junior Subordinated Deferrable Interest Debentures Due 2027 To 2034 [Member]	Sep. 30, 2014 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]	Dec. 31, 2013 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]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Puerto Rico States And Political Subdivisions Debt Securities [Member]	Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure Puerto Rico States And Political Subdivisions Debt Securities [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure Collateralized Mortgage Obligations Issued By U S Government Sponsored Enterprises And U S Government [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Other Securities [Member]	Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure Other Securities [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Non Covered Under Loss Sharing Agreements With F D I C [Member]	Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure Non Covered Under Loss Sharing Agreements With F D I C [Member]	Sep. 30, 2014 Estimate of Fair Value, Fair Value Disclosure Covered Under Loss Sharing Agreements With F D I C [Member]	Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure Covered Under Loss Sharing Agreements With F D I C [Member]	Sep. 30, 2014 Notional Amount [Member]	Dec. 31, 2013 Notional Amount [Member]
Assets, Fair Value Disclosure [Abstract]
Cash And Due From Banks	$ 321,914	$ 423,211	$ 368,590	$ 439,363																		$ 321,914		$ 423,211														$ 0		$ 0														$ 0		$ 0																										$ 321,914		$ 423,211																		$ 321,914		$ 423,211
Money market investments	1,053,121	858,453																				906,314		677,033														146,807		181,420														0		0																										1,053,121		858,453																		1,053,121		858,453
Trading account securities, at fair value	145,343	339,743																				0	[1]	0	[1]													135,009	[1]	326,509	[1]													10,334	[1]	13,151	[1]																									145,343	[1]	339,660	[1]																	145,343	[1]	339,660	[1]
Available For Sale Securities	5,727,766	5,294,800												66,118	66,377	6	513	2,135,074	2,418,296	11,543	12,170	303	[1]	412	[1]													5,721,537	[1]	5,287,865	[1]													5,926	[1]	6,523	[1]																									5,727,766	[1]	5,294,800	[1]																	5,727,766	[1]	5,294,800	[1]
Held To Maturity Securities Fair Value	103,120	120,688												101,513	94,712	0	0	107	122	1,500	25,854	0		0								0	0	0	0	0	0	1,500		1,500								0	0	0	0	1,500	1,500	101,620		119,188								101,513	94,712	107	122	0	24,354													112,893		140,496								111,292	113,881	101	115	1,500	26,500					103,120		120,688								101,513	94,712	107	122	1,500	25,854
Marketable Securities, Alternative [Abstract]
Federal Home Loan Bank Stock																						0		0														66,233		85,245														0		0																										66,233		85,245																		66,233		85,245
Federal Reserve Bank Stock																						0		0														79,826		80,385														0		0																										79,826		80,385																		79,826		80,385
Trust Preferred Securities																						0		0														12,197		13,197														1,000		1,000																										13,197		14,197																		13,197		14,197
Other Investments																						0		0														0		0														4,519		4,699																										1,912		1,925																		4,519		4,699
Total other investment securities																						0		0														158,256		178,827														5,519		5,699																										161,168		181,752																		163,775		184,526
Loans held-for-sale																						0		0														92,459		3,155														92,327		109,405																										178,008		110,426																		184,786		112,560
FDIC loss share asset																						0		0														0		0														540,889		837,131																										681,106		948,608																		540,889		837,131
Loans held-in-portfolio, net																																																																						0	0	0	0	17,629,704	19,070,337	0	0	0	0	2,999,580	3,404,128																	18,837,529	21,073,403	2,564,575	2,882,335																				17,629,704	19,070,337	2,999,580	3,404,128
Servicing Asset At Fair Value Amount	152,282	161,099	161,445	154,430																		0		0														0		0														152,282		161,099																										152,282		161,099																		152,282		161,099
Derivative Asset, Fair Value, Gross Asset	25,850	34,710																				0		0														25,850		34,793														0		0																										25,850		34,793																		25,850		34,793
Deposits, by Type [Abstract]
Demand Deposit Accounts																						0		0														16,964,395		18,399,793														0		0																										16,964,395		18,399,793																		16,964,395		18,399,793
Time Deposits	7,501,711	8,311,352																				0		0														7,542,808		8,367,410														0		0																										7,501,710		8,311,352																		7,542,808		8,367,410
Deposits																						0		0														24,507,203		26,767,203														0		0																										24,466,105		26,711,145																		24,507,203		26,767,203
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase																						0		0		0	0											1,654,179		1,025,628		0	694,422											0		0		0	0																							1,650,712		1,021,102		0	638,190															1,654,179		1,025,628		0	694,422
Assets sold under agreements to repurchase																						0		0														1,654,179		1,720,050														0		0																										1,650,712		1,659,292																		1,654,179		1,720,050
Other short-term borrowings																						0	[2]	0	[2]													1,200	[2]	401,200	[2]													0	[2]	0	[2]																									1,200	[2]	401,200	[2]																	1,200	[2]	401,200	[2]
Notes Payable [Abstract]
Federal Home Loan Bank Advances Long Term																						0		0														823,243		604,976														0		0																										810,202		589,229																		823,243		604,976
Medium-term Notes																						0		0														0		0														691		716																										679		689																		691		716
Senior Long Term Notes											450,000	450,000	0																																																																					450,000																				455,423																0	455,423	0
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust					439,800	439,800	0	[3]	531,540	[3]																		0	0	0	0													376,031	348,222	0	0													0	0	0	1,006,638																									439,800	439,800	0	531,540																	376,031	348,222	0	1,006,638
Other Notes Payable	22,892	23,496																				0		0														0		0														22,892		23,496																										22,892		23,496																		22,892		23,496
Notes payable																						0		0														1,654,696		953,198														23,583		1,030,850																										1,723,573		1,584,754																		1,678,280		1,984,048
Derivative Financial Instruments Liabilities Fair Value Disclosure																						0		0														23,796		32,378														0		0																										23,796		32,378																		23,796		32,378
Business Combination Contingent Consideration Liability																						0		0														0		0														126,473		128,299																										126,473		128,299																		126,473		128,299
Fair Value Off Balance Sheet [Abstract]
Commitments to extend credit																						0		0														0		0														1,680		2,571																																														1,680		2,571																					7,033,358	7,490,927
Letters of credit Fair Value Disclosure																						$ 0		$ 0														$ 0		$ 0														$ 544		$ 901																																														$ 544		$ 901																					$ 47,296	$ 82,007

[1] Refer to Note 27 to the consolidated financial statements for the fair value by class of financial asset and its hierarchy level.

[2] Refer to Note 18 to the consolidated financial statements for the composition of short-term borrowings.

[3] 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 was being amortized over an estimated 30-year term that started in August 2009. During the quarter ended June 30, 2014, in connection with the repayment of these Notes completed on July 2, 2014, the Corporation accelerated the related amortization of the discount and deferred costs amounting to $414.1 million, which is reflected as interest expense in the consolidated statement of operations. The effective interest rate, including the discount accretion, was approximately 16% at December 31, 2013.