Transactions with Related Parties Transactions with Related Parties (Detail) - Kinetica [Member] $ in Millions	Dec. 31, 2013 USD ($)
Schedule Of Other Related Party Transactions [Line Items]
Surety bonds issued	$ 13
Percentage of investment ownership	10.00%

Percentage ownership by Board of Directors member in entity with which the company has a related party transaction.

No definition available.

Name:	argo_OwnershipPercentageByDirectorRelatedPartyTransaction
Namespace Prefix:	argo_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant