XML 103 R64.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Reinsurance - Schedule of the Effect of Reinsurance on Premiums Written and Earned (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Premiums Written And Earned [Abstract] |  |  |
Gross Written | $ 372,177 | $ 328,823 | $ 272,101
Ceded Written | (18,425) | (16,305) | (13,881)
Net premiums Written | 353,752 | 312,518 | 258,220
Gross Earned | 348,408 | 306,994 | 264,896
Ceded Earned | (18,425) | (16,305) | (13,881)
Net premiums Earned | $ 329,983 | $ 290,689 | $ 251,015

X
- Definition Amount, before premiums ceded to other entities of premiums earned. + References No definition available. + Details
Name: | amsf_PremiumsEarnedGross
Namespace Prefix: | amsf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of earned premiums ceded to other entities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 17 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17) -URI http://asc.fasb.org/extlink&oid=6588446&loc=d3e574992-122915 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.1) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c)(2) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 1 -Article 7 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6486662&loc=d3e27175-158546 + Details
Name: | us-gaap_CededPremiumsEarned
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of written premiums ceded to other entities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 17 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c)(2) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_CededPremiumsWritten
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, after premiums ceded to other entities and premiums assumed by the entity, of property and casualty premiums earned. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.1) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 1 -Article 7 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6486662&loc=d3e27175-158546 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_PremiumsEarnedNetPropertyAndCasualty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition Amount of direct and assumed premiums written. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_PremiumsWrittenGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums written. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 17 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_PremiumsWrittenNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration