Subsequent Event - Additional Information (Detail) - Argo Underwriting Agency Limited - Disposal Group, Disposed of by Sale, Not Discontinued Operations - USD ($) $ in Millions	Feb. 02, 2023	Sep. 08, 2022
Subsequent Event [Line Items]
Cash consideration received from sale		$ 125.0
Subsequent Event
Subsequent Event [Line Items]
Cash consideration received from sale	$ 155.6
Consideration placed in escrow	30.6
Proceeds from sale of business unit	$ 125.0
Period for which consideration can be released to Seller	2 years

Disposal Group, Including Discontinued Operation, Consideration Placed in Escrow

No definition available.

Name:	argo_DisposalGroupIncludingDiscontinuedOperationConsiderationPlacedInEscrow
Namespace Prefix:	argo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Disposal Group, Including Discontinued Operation, Consideration Placed in Escrow, Term

+ References

No definition available.

+ Details

Name:	argo_DisposalGroupIncludingDiscontinuedOperationConsiderationPlacedInEscrowTerm
Namespace Prefix:	argo_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3179-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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