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Other Equity Instruments - Summary of Coupon Details - Summary of Perpetual Contingent Convertible (Parenthetical) (Detail) - EUR (€)
Dec. 31, 2019
Dec. 31, 2018
EUR 500 million [member] | Aegon N.V [member] | Perpetual contingent convertible securities [member]    
Disclosure of other equity instruments [line items]    
Principal amount € 500,000,000 € 500,000,000