XML 82 R66.htm IDEA: XBRL DOCUMENT
v3.22.4

Reinsurance - Schedule of Unsecured Reinsurance Recoverables from Reinsurers (Detail) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Ceded Credit Risk [Line Items] |  |  |
Total reinsurance recoverables |  | $ 125,677 | $ 120,561
Allowance for credit losses |  | (372) | $ (440)
Funds withheld and letters of credit related to the above recoverables |  | (80,549) |
Total unsecured amounts recoverable from reinsurers |  | 45,128 |
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk |  |  |
Ceded Credit Risk [Line Items] |  |  |
Total reinsurance recoverables |  | 125,677 |
Total amounts recoverable from reinsurers |  | 126,049 |
Allowance for credit losses |  | (372) |
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Hannover Reinsurance (Ireland) Limited [Member] | A.M. Best Rating, A+ [Member] |  |  |
Ceded Credit Risk [Line Items] |  |  |
Total reinsurance recoverables | [1] | 63,987 |
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Arch Reinsurance Company |  |  |
Ceded Credit Risk [Line Items] |  |  |
Total reinsurance recoverables | [1] | 11,358 |
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Allianz Risk Transfer AG (Bermuda) [Member] | A.M. Best Rating, A+ [Member] |  |  |
Ceded Credit Risk [Line Items] |  |  |
Total reinsurance recoverables |  | 9,489 |
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Minnesota Workers' Compensation Reinsurance Association [Member] |  |  |
Ceded Credit Risk [Line Items] |  |  |
Total reinsurance recoverables | [1] | 8,567 |
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Odyssey America Reinsurance Corporation [Member] | A.M. Best Rating, A [Member] |  |  |
Ceded Credit Risk [Line Items] |  |  |
Total reinsurance recoverables |  | 6,516 |
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Other Reinsurers [Member] |  |  |
Ceded Credit Risk [Line Items] |  |  |
Total reinsurance recoverables |  | $ 26,132 |
[1] | Current participant in our 2023 reinsurance program.

X
- Definition Letters of credit from the reinsurer and Amount of the reinsurer's funds held on its behalf by the ceding insurer, including funds held in trust, under reinsurance treaties or contracts with the assuming insurer as security for the payment of the obligations there under. + References No definition available. + Details
Name: | amsf_FundsHeldAndLettersOfCredit
Namespace Prefix: | amsf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Unsecured amounts recoverables from reinsurance net. + References No definition available. + Details
Name: | amsf_UnsecuredAmountsRecoverablesFromReinsuranceNet
Namespace Prefix: | amsf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_CededCreditRiskLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(6)) -URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 45 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489 + Details
Name: | us-gaap_ReinsuranceRecoverables
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of allowance for credit loss on reinsurance recoverable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446 + Details
Name: | us-gaap_ReinsuranceRecoverablesAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before valuation allowance recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919253-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953401-111524 + Details
Name: | us-gaap_ReinsuranceRecoverablesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_ReinsuranceRecoverableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByTypeAxis=us-gaap_ReinsurerConcentrationRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=amsf_HannoverReinsuranceIrelandLimitedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CreditRatingAMBestAxis=srt_AMBestAPlusRatingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=amsf_ArchReinsuranceCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=amsf_AllianzRiskTransferAGBermudaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=amsf_MinnesotaWorkersCompensationReinsuranceAssociationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=amsf_OdysseyAmericaReinsuranceCorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CreditRatingAMBestAxis=srt_AMBestARatingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=amsf_OtherReinsurersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |