CASH COLLATERAL, REVERSE REPURCHASE AGREEMENTS AND SECURITIES BORROWING AND PAYABLES FROM REPURCHASE AGREEMENTS AND SECURITIES LENDING - Payables on repurchase agreements and securities lending (Details) - PEN (S/)
S/ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Jan. 01, 2018
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities     S/ 139,747,905
Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities S/ 7,678,016 S/ 9,415,357  
Financial liabilities, at fair value 8,067,239 10,049,889  
Debt instruments [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 6,331,465 7,944,790  
Debt instruments [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 6,331,465 7,944,790  
Financial liabilities, at fair value S/ 6,709,182 S/ 8,572,837  
Instruments issued by the Colombian Government [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Description of presentation currency Colombian pesos    
Borrowings, interest rate 5.49% 5.97%  
Financial liabilities S/ 1,077,428 S/ 1,234,763  
Financial liabilities, at fair value S/ 1,077,917 S/ 1,235,472  
Instruments issued by the Chilean Government [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Description of presentation currency Chilean pesos    
Borrowings, interest rate 0.20% 0.26%  
Financial liabilities S/ 174,962 S/ 24,912  
Financial liabilities, at fair value S/ 175,054 S/ 27,529  
Other instruments [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Borrowings, interest rate 2.07% 1.88%  
Financial liabilities S/ 94,161 S/ 210,892  
Financial liabilities, at fair value 105,086 214,051  
Not later than three days [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 402,445 329,150  
Not later than three days [Member] | Debt instruments [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 64,900 159,570  
Not later than three days [Member] | Instruments issued by the Colombian Government [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 135,997 0  
Not later than three days [Member] | Instruments issued by the Chilean Government [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 130,551 24,912  
Not later than three days [Member] | Other instruments [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 70,997 144,668  
Later than three and not later than thirty days [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 1,028,350 1,663,064  
Later than three and not later than thirty days [Member] | Debt instruments [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 25,699 365,201  
Later than three and not later than thirty days [Member] | Instruments issued by the Colombian Government [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 941,431 1,231,639  
Later than three and not later than thirty days [Member] | Instruments issued by the Chilean Government [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 44,411 0  
Later than three and not later than thirty days [Member] | Other instruments [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 16,809 66,224  
Later than thirty days [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 6,247,221 7,423,143  
Later than thirty days [Member] | Debt instruments [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 6,240,866 7,420,019  
Later than thirty days [Member] | Instruments issued by the Colombian Government [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 0 3,124  
Later than thirty days [Member] | Instruments issued by the Chilean Government [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities 0 0  
Later than thirty days [Member] | Other instruments [Member] | Payables from repurchase agreements and security lendings [Member]      
Disclosure of Cash Collateral, Reverse Repurchase Agreements And Securities Borrowings And Payables From Repurchase Agreements And Security Lendings [Line Items]      
Financial liabilities S/ 6,355 S/ 0