Financial Risks - Summary of Maturity Analysis Gross Undiscounted Contractual Cash Flows (Detail) - EUR (€) € in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]
Trust pass-through securities	€ 133	€ 133
Subordinated loans	1,389	764
Borrowings	12,061	13,635
Investment contracts for account of policyholders	18,048	16,943
Contractual maturities of each category of financial liabilities [member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]
Trust pass-through securities	223	221
Subordinated loans	1,933	1,333
Borrowings	14,174	15,362
Investment contracts	19,077	17,448
Investment contracts for account of policyholders	49,166	36,478
Other financial liabilities	8,457	9,125
Total financial liabilities (excluding investment/ insurance contracts)	24,787	26,041
On demand [member] \| Contractual maturities of each category of financial liabilities [member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]
Investment contracts	13,305	12,189
Investment contracts for account of policyholders	29,360	33,738
Other financial liabilities	5,849	6,277
Total financial liabilities (excluding investment/ insurance contracts)	5,849	6,277
Not later than 1 year [member] \| Contractual maturities of each category of financial liabilities [member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]
Trust pass-through securities	9	9
Subordinated loans	66	28
Borrowings	1,713	1,888
Investment contracts	1,439	1,381
Investment contracts for account of policyholders	19,670	2,605
Other financial liabilities	2,445	2,002
Total financial liabilities (excluding investment/ insurance contracts)	4,234	3,926
1-5 years [member] \| Contractual maturities of each category of financial liabilities [member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]
Trust pass-through securities	36	34
Subordinated loans	266	112
Borrowings	8,136	8,396
Investment contracts	1,831	1,591
Investment contracts for account of policyholders	20	1
Other financial liabilities	81	791
Total financial liabilities (excluding investment/ insurance contracts)	8,519	9,333
Over 5 through 10 years [member] \| Contractual maturities of each category of financial liabilities [member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]
Trust pass-through securities	110	110
Subordinated loans	201	56
Borrowings	1,499	2,411
Investment contracts	985	577
Investment contracts for account of policyholders	26	1
Other financial liabilities	45	23
Total financial liabilities (excluding investment/ insurance contracts)	1,854	2,599
Over 10 years [member] \| Contractual maturities of each category of financial liabilities [member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]
Trust pass-through securities	69	68
Subordinated loans	1,400	1,137
Borrowings	2,825	2,668
Investment contracts	1,517	1,709
Investment contracts for account of policyholders	91	133
Other financial liabilities	38	32
Total financial liabilities (excluding investment/ insurance contracts)	€ 4,332	€ 3,905

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The amount of outstanding funds that the entity is obligated to repay.

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The amount of contractual undiscounted cash flows in relation to contractual amounts to be exchanged in a derivative financial instrument for which gross cash flows are exchanged. [Refer: Derivatives [member]]

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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No definition available.

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The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to deliver a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]]

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The amount of liabilities relating to investment contracts that fall within the scope of IAS 39 or IFRS 9.

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The amount of financial liabilities that the entity does not separately disclose in the same statement or note. [Refer: Financial liabilities]

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The amount of liabilities that are subordinate to other liabilities with respect to claims.

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