Offsetting, Enforceable Master Netting Arrangements and Similar Agreements - Summary of Financial Instruments Set Off in Statement of Financial Position (Detail) - EUR (€) € in Millions	Dec. 31, 2021	Dec. 31, 2020
Disclosure of offsetting of financial assets and financial liabilities [line items]
Gross amounts of recognized financial assets	€ 8,811	€ 14,030
Gross amounts of recognized financial liabilities set off in the statement of financial position
Net amounts of financial assets presented in the statement of financial position	8,811	14,030
Related amounts not set off in the statements of financial position, Financial instruments	6,045	8,778
Related amounts not set off in the statements of financial position, Cash collateral received (excluding surplus collateral)	2,519	5,224
Net amount	247	27
Financial liabilities subject to offsetting, enforceable master netting arrangements and similar agreements
Gross amounts of recognized financial liabilities	7,043	9,633
Gross amounts of recognized financial assets set off in the statement of financial position	0	0
Net amounts of financial liabilities presented in the statement of financial position	7,043	9,633
Related amounts not set off in the statements of financial position, Financial instruments	6,768	9,436
Related amounts not set off in the statements of financial position, Cash collateral pledged (excluding surplus collateral)	224	170
Net amount	52	28
Derivatives [member]
Disclosure of offsetting of financial assets and financial liabilities [line items]
Gross amounts of recognized financial assets	8,811	14,030
Gross amounts of recognized financial liabilities set off in the statement of financial position
Net amounts of financial assets presented in the statement of financial position	8,811	14,030
Related amounts not set off in the statements of financial position, Financial instruments	6,045	8,778
Related amounts not set off in the statements of financial position, Cash collateral received (excluding surplus collateral)	2,519	5,224
Net amount	247	27
Financial liabilities subject to offsetting, enforceable master netting arrangements and similar agreements
Gross amounts of recognized financial liabilities	7,043	9,633
Gross amounts of recognized financial assets set off in the statement of financial position	0	0
Net amounts of financial liabilities presented in the statement of financial position	7,043	9,633
Related amounts not set off in the statements of financial position, Financial instruments	6,768	9,436
Related amounts not set off in the statements of financial position, Cash collateral pledged (excluding surplus collateral)	224	170
Net amount	€ 52	€ 28

Disclosure of offsetting of financial assets and financial liabilities line items.

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The amount of cash collateral pledged that is subject to an enforceable master netting arrangement or similar agreement and that is not set off against financial liabilities. [Refer: Financial liabilities]

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The amount of cash collateral received that is subject to an enforceable master netting arrangement or similar agreement and that is not set off against financial assets. [Refer: Financial assets]

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The amount of financial instruments subject to an enforceable master netting arrangement or similar agreement that are not set off against financial assets. [Refer: Financial assets]

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The amount of financial instruments subject to an enforceable master netting arrangement or similar agreement that are not set off against financial liabilities. [Refer: Financial liabilities]

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The amount of financial assets set off against financial liabilities when an entity: (a) currently has a legally enforceable right to set off the recognised amounts; and (b) intends either to settle on a net basis, or to realise the asset and settle the liability simultaneously. [Refer: Financial assets; Financial liabilities]

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The gross amount of recognised financial assets that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement. [Refer: Financial assets]

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The amount of financial liabilities set off against financial assets when an entity: (a) currently has a legally enforceable right to set off the recognised amounts; and (b) intends either to settle on a net basis or to realise the asset and settle the liability simultaneously. [Refer: Financial assets; Financial liabilities]

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The gross amount of recognised financial liabilities that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement. [Refer: Financial liabilities]

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The amount remaining after deducting the amounts subject to an enforceable master netting arrangement or similar agreement that were not set off against financial assets, from the net amount of financial assets subject to offsetting or subject to an enforceable master netting arrangement or similar agreement presented in the statement of financial position.

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The net amount of financial assets that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement, presented in the statement of financial position. [Refer: Financial assets]

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The amount remaining after deducting the amounts subject to an enforceable master netting arrangement or similar agreement that were not set off against financial liabilities, from the net amount of financial liabilities subject to offsetting or subject to an enforceable master netting arrangement or similar agreement presented in the statement of financial position.

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The net amount of financial liabilities that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement, presented in the statement of financial position. [Refer: Financial liabilities]

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