INVESTMENTS - Investment at fair value (Details) - PEN (S/)
S/ in Thousands
Dec. 31, 2019
Dec. 31, 2018
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss S/ 3,850,762 S/ 3,512,445
Government Treasury Bonds [Member]    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 1,276,573 1,318,311
Colombian Treasury bonds    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 1,102,865 1,259,516
Peruvian treasury bonds [Member]    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 95,308 58,795
U.S. treasury and federal agency bonds    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 78,400  
Mutual funds    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 593,552 397,918
Restricted mutual funds [Member]    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 460,086 407,350
Corporate bonds    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 326,673 160,006
Investment funds    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 327,659 179,015
Participation in RAL Fund [Member]    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 300,398 445,039
Central Bank of Chile bonds    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 182,540 30,382
Shares    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 83,085 101,068
Subordinated bonds    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 80,084 94,413
Royalty Pharma    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 68,584 56,787
Multilateral organization bonds [Member]    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 53,353 193,395
Others    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 93,204 123,892
Accrued interest    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss 4,971 4,869
Financial assets at fair value through profit or loss, classified as held for trading, category [Member]    
Disclosure of Investments [Line Items]    
Non-current financial assets at fair value through profit or loss S/ 3,845,791 S/ 3,507,576