v2.4.0.6

Segments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 9 Months Ended
--- | ---
Sep. 30, 2012
Specialty Risk and Extended Warranty |
Segment Reporting Information [Line Items] |
Gross written premium | $ 125,900
Specialty Program |
Segment Reporting Information [Line Items] |
Gross written premium | $ 87,150

X
- Definition Premiums Written, Gross, from Broker + References No definition available. + Details
Name: | afsi_PremiumsWrittenGrossFromBroker
Namespace Prefix: | afsi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration