Note Fair value of financial instruments (Carrying or notional amounts and estimated fair values for financial instruments) (Detail) - USD ($) $ in Thousands		Sep. 30, 2017		Dec. 31, 2016		Sep. 30, 2016	Dec. 31, 2015
Financial Assets:
Cash And Due From Banks		$ 517,437		$ 362,394
Money market investments		5,488,212		2,890,217
Trading account securities, excluding derivatives		45,951		59,805
Available For Sale Securities		9,061,001	[1]	8,209,806	[2]
Investment securities held-to-maturity, at amortized cost		93,438	[3]	98,101	[4]
Held To Maturity Securities Fair Value		74,512	[3]	75,576	[4]
Other investment securities
FDIC loss-share asset		48,470		69,334
Mortgage servicing rights		180,157		196,889		$ 200,354	$ 211,405
Derivatives		14,234		14,094
Deposits
Time deposits		7,612,523		7,709,542
Total deposits		34,248,936		30,496,224
Notes payable:
Others		17,294		18,071
Notes Payable		1,532,061		1,574,852
Carrying amount
Financial Assets:
Cash And Due From Banks		517,437		362,394
Money market investments		5,488,212		2,890,217
Trading account securities, excluding derivatives	[5]	45,951		59,796
Available For Sale Securities	[5]	9,061,001		8,209,806
Investment securities held-to-maturity, at amortized cost		93,438		98,101
Other investment securities
FHLB Stock		64,208		58,033
FRB stock		94,644		94,672
Trust preferred securities fair value		13,198		13,198
Other investments		1,915		1,915
Total other investment securities		173,965		167,818
Loans held-for-sale		68,864		88,821
Loans covered under loss sharing agreements with the FDIC		491,797		542,528
FDIC loss-share asset		48,470		69,334
Mortgage servicing rights		180,157		196,889
Derivatives		14,234		14,094
Deposits
Demand deposits		26,636,413		22,786,682
Time deposits		7,612,523		7,709,542
Total deposits		34,248,936		30,496,224
Federal funds purchased and assets sold under agreements to repurchase		374,405		479,425
Other short-term borrowings	[6]	240,598		1,200
Notes payable:
Advances with the FHLB		629,072		672,670
Senior Long Term Notes		446,351		444,788
Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust		439,344		439,323
Others		17,294		18,071
Notes Payable		1,532,061		1,574,852
Derivatives		12,841		12,842
Contingent consideration		166,876		153,158
Fair Value
Financial Assets:
Cash And Cash Equivalents Fair Value Disclosure		517,437		362,394
Money Market Investments Fair Value		5,488,212		2,890,217
Trading account securities, excluding derivatives		45,951		59,796
Available For Sale Securities		9,061,001		8,209,806
Held To Maturity Securities Fair Value		74,512		75,576
Other investment securities
FHLB Stock		64,208		58,033
FRB stock		94,644		94,672
Trust preferred securities		13,198		13,198
Other investments		5,091		4,987
Total other investment securities		177,141		170,890
Loans held-for-sale		70,499		90,013
F D I C Indemnification Asset Fair Value Portion		37,703		63,187
Mortgage servicing rights		180,157		196,889
Derivatives		14,234		14,094
Deposits
Demand deposits		26,636,413		22,786,682
Time deposits		7,504,546		7,708,724
Deposits		34,140,959		30,495,406
Federal funds purchased and assets sold under agreements to repurchase		374,377		479,439
Other short-term borrowings		240,598		1,200
Notes payable:
FHLB advances		629,538		671,872
Unsecured senior debt securities		470,043		466,263
Junior subordinated deferrable interest debentures		411,776		399,370
Others		17,294		18,071
Notes payable		1,528,651		1,555,576
Derivatives		12,841		12,842
Contingent consideration		166,876		153,158
Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Available For Sale Securities		6,615		22,771
Investment securities held-to-maturity, at amortized cost		92,369		96,027
Held To Maturity Securities Fair Value		73,460		73,540
Obligations of Puerto Rico, States and political subdivisions | Carrying amount
Financial Assets:
Investment securities held-to-maturity, at amortized cost		92,369		96,027
Obligations of Puerto Rico, States and political subdivisions | Fair Value
Financial Assets:
Held To Maturity Securities Fair Value		73,460		73,540
Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Available For Sale Securities		1,015,597		1,221,526
Investment securities held-to-maturity, at amortized cost		69		74
Held To Maturity Securities Fair Value		73		78
Collateralized Mortgage Obligations - Federal agencies | Carrying amount
Financial Assets:
Investment securities held-to-maturity, at amortized cost		69		74
Collateralized Mortgage Obligations - Federal agencies | Fair Value
Financial Assets:
Held To Maturity Securities Fair Value		73		78
Other
Financial Assets:
Available For Sale Securities		869		9,585
Investment securities held-to-maturity, at amortized cost		1,000		2,000
Held To Maturity Securities Fair Value		979		1,958
Other | Carrying amount
Financial Assets:
Investment securities held-to-maturity, at amortized cost		1,000		2,000
Other | Fair Value
Financial Assets:
Held To Maturity Securities Fair Value		979		1,958
Level 1
Financial Assets:
Cash And Cash Equivalents Fair Value Disclosure		517,437		362,394
Money Market Investments Fair Value		5,479,268		2,854,777
Trading account securities, excluding derivatives	[5]	0		0
Available For Sale Securities	[5]	0		0
Held To Maturity Securities Fair Value		0		0
Other investment securities
FHLB Stock		0		0
FRB stock		0		0
Trust preferred securities		0		0
Other investments		0		0
Total other investment securities		0		0
Loans held-for-sale		0		0
F D I C Indemnification Asset Fair Value Portion		0		0
Mortgage servicing rights		0		0
Derivatives		0		0
Deposits
Demand deposits		0		0
Time deposits		0		0
Deposits		0		0
Federal funds purchased and assets sold under agreements to repurchase		0		0
Other short-term borrowings	[6]	0		0
Notes payable:
FHLB advances		0		0
Unsecured senior debt securities		0		0
Junior subordinated deferrable interest debentures		0		0
Others		0		0
Notes payable		0		0
Derivatives		0		0
Contingent consideration		0		0
Level 1 | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Held To Maturity Securities Fair Value		0		0
Level 1 | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Held To Maturity Securities Fair Value		0		0
Level 1 | Other
Financial Assets:
Held To Maturity Securities Fair Value		0		0
Level 2
Financial Assets:
Cash And Cash Equivalents Fair Value Disclosure		0		0
Money Market Investments Fair Value		8,944		35,440
Trading account securities, excluding derivatives	[5]	44,787		53,118
Available For Sale Securities	[5]	9,059,713		8,208,414
Held To Maturity Securities Fair Value		742		1,738
Other investment securities
FHLB Stock		64,208		58,033
FRB stock		94,644		94,672
Trust preferred securities		13,198		13,198
Other investments		0		0
Total other investment securities		172,050		165,903
Loans held-for-sale		0		504
F D I C Indemnification Asset Fair Value Portion		0		0
Mortgage servicing rights		0		0
Derivatives		14,234		14,094
Deposits
Demand deposits		26,636,413		22,786,682
Time deposits		7,504,546		7,708,724
Deposits		34,140,959		30,495,406
Federal funds purchased and assets sold under agreements to repurchase		374,377		479,439
Other short-term borrowings	[6]	240,598		1,200
Notes payable:
FHLB advances		629,538		671,872
Unsecured senior debt securities		470,043		466,263
Junior subordinated deferrable interest debentures		411,776		399,370
Others		0		0
Notes payable		1,511,357		1,537,505
Derivatives		12,841		12,842
Contingent consideration		0		0
Level 2 | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Held To Maturity Securities Fair Value		0		0
Level 2 | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Held To Maturity Securities Fair Value		0		0
Level 2 | Other
Financial Assets:
Held To Maturity Securities Fair Value		742		1,738
Level 3
Financial Assets:
Cash And Cash Equivalents Fair Value Disclosure		0		0
Money Market Investments Fair Value		0		0
Trading account securities, excluding derivatives	[5]	1,164		6,678
Available For Sale Securities	[5]	1,288		1,392
Held To Maturity Securities Fair Value		73,770		73,838
Other investment securities
FHLB Stock		0		0
FRB stock		0		0
Trust preferred securities		0		0
Other investments		5,091		4,987
Total other investment securities		5,091		4,987
Loans held-for-sale		70,499		89,509
F D I C Indemnification Asset Fair Value Portion		37,703		63,187
Mortgage servicing rights		180,157		196,889
Derivatives		0		0
Deposits
Demand deposits		0		0
Time deposits		0		0
Deposits		0		0
Federal funds purchased and assets sold under agreements to repurchase		0		0
Other short-term borrowings	[6]	0		0
Notes payable:
FHLB advances		0		0
Unsecured senior debt securities		0		0
Junior subordinated deferrable interest debentures		0		0
Others		17,294		18,071
Notes payable		17,294		18,071
Derivatives		0		0
Contingent consideration		166,876		153,158
Level 3 | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Held To Maturity Securities Fair Value		73,460		73,540
Level 3 | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Held To Maturity Securities Fair Value		73		78
Level 3 | Other
Financial Assets:
Held To Maturity Securities Fair Value		237		220
Non-covered loans | Carrying amount
Other investment securities
Loans held in portfolio, net		22,559,594		22,263,446
Non-covered loans | Fair Value
Other investment securities
Loans Receivable, Fair Value Disclosure		20,896,277		20,578,904
Non-covered loans | Level 1
Other investment securities
Loans Receivable, Fair Value Disclosure		0		0
Non-covered loans | Level 2
Other investment securities
Loans Receivable, Fair Value Disclosure		0		0
Non-covered loans | Level 3
Other investment securities
Loans Receivable, Fair Value Disclosure		20,896,277		20,578,904
Covered loans | Fair Value
Other investment securities
Loans Receivable, Fair Value Disclosure		483,155		515,808
Covered loans | Level 1
Other investment securities
Loans Receivable, Fair Value Disclosure		0		0
Covered loans | Level 2
Other investment securities
Loans Receivable, Fair Value Disclosure		0		0
Covered loans | Level 3
Other investment securities
Loans Receivable, Fair Value Disclosure		$ 483,155		$ 515,808

[1] Includes $6.7 billion pledged to secure public and trust deposits, assets sold under agreements to repurchase, credit facilities and loan servicing agreements that the secured parties are not permitted to sell or repledge the collateral, of which $5.7 billion serve as collateral for public funds.

[2] Includes $4.1 billion pledged to secure public and trust deposits, assets sold under agreements to repurchase, credit facilities and loan servicing agreements that the secured parties are not permitted to sell or repledge the collateral, of which $3.4 billion serve as collateral for public funds.

[3] Includes $92.4 million pledged to secure public and trust deposits that the secured parties are not permitted to sell or repledge the collateral.

[4] Includes $53.1 million pledged to secure public and trust deposits that the secured parties are not permitted to sell or repledge the collateral.

[5] Refer to Note 25 to the C onsolidated F inancial S tatements for the fair value by class of financial asset and its hierarchy level.

[6] Refer to Note 17 to the Consolidated F inancial S tatements for the composition of other short-term borrowings.