Defined Benefit Plans - Summary of Target Allocation of Plan Assets for Retirement Benefit Plans for the Next Annual Period (Detail)	Dec. 31, 2021	Dec. 31, 2020
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
Equity instruments	0.00%	3.00%
Debt instruments	21.00%	26.00%
Aegon United Kingdom [member] \| Actuarial assumption of expected rates of pension increases [member] \| Defined benefit plans [member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
Equity instruments	16.70%
Debt instruments	83.30%

The percentage instruments representing debt (rather than equity) contribute to the fair value of defined benefit plan assets. [Refer: Plan assets, at fair value; Defined benefit plans [member]] [Contrast: Debt instruments, amount contributed to fair value of plan assets]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 142
-Subparagraph c
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-URIDate 2021-03-24

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- Definition

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

+ References

No definition available.

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- Definition

The percentage equity instruments contribute to the fair value of defined benefit plan assets. [Refer: Plan assets, at fair value; Defined benefit plans [member]] [Contrast: Equity instruments, amount contributed to fair value of plan assets]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 142
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_142_b&doctype=Standard
-URIDate 2021-03-24

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