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Long-Term Borrowings - Additional Information (Detail) - Aegon N.V [member] - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Disclosure of long-term borrowings [Line Items]    
Long-term borrowing, market value € 1,728 € 1,649
Bottom of range [member]    
Disclosure of long-term borrowings [Line Items]    
Borrowing maturity 4 years  
Long-term borrowing, interest rate 1.00%  
Top of range [member]    
Disclosure of long-term borrowings [Line Items]    
Borrowing maturity 19 years  
Long-term borrowing, interest rate 6.625%