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Leases - Schedule of Supplemental Balance Sheet Information Related to Leases (Detail) $ in Thousands | Mar. 31, 2019 USD ($)
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Leases [Abstract] |
Operating lease right-of-use assets | $ 539
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] | us-gaap:OtherAssets
Operating lease liabilities | $ 539
Operating Lease, Liability, Statement of Financial Position [Extensible List] | amsf:AccountsPayableAndOtherLiabilities
Finance lease right-of-use assets | $ 185
Finance lease accumulated amortization right-of-use assets | (133)
Property and equipment, net | $ 52
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] | us-gaap:PropertyPlantAndEquipmentNet
Finance lease liabilities | $ 90
Finance Lease, Liability, Statement of Financial Position [Extensible List] | amsf:AccountsPayableAndOtherLiabilities

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- Definition Accumulated amortization of finance lease right of use assets. + References No definition available. + Details
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- Definition Finance lease right of use asset, net. + References No definition available. + Details
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- Definition Present value of lessee's discounted obligation for lease payments from finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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- Definition Indicates line item in statement of financial position that includes finance lease liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918631-209977 + Details
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- Definition Amount of lessee's right to use underlying asset under finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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- Definition Indicates line item in statement of financial position that includes finance lease right-of-use asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918631-209977 + Details
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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- Definition Indicates line item in statement of financial position that includes operating lease liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918631-209977 + Details
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- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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