XML 34 R24.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Fair Value Measurements (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2018
Fair Value Disclosures [Abstract] |
Schedule of Assets Measured at Fair Value on Recurring Basis | At September 30, 2018, assets measured at fair value on a recurring basis are summarized below:
|  | September 30, 2018 |
|  | Level 1 Inputs |  |  | Level 2 Inputs |  |  | Level 3 Inputs |  |  | Total Fair Value |
|  | (in thousands) |
Financial instruments carried at fair value, classified as a part of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Securities available-for-sale—fixed maturity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
States and political subdivisions |  | $ | — |  |  | $ | 227,487 |  |  | $ | — |  |  | $ | 227,487 |
Corporate bonds |  |  | — |  |  |  | 162,948 |  |  |  | — |  |  |  | 162,948 |
U.S. agency-based mortgage-backed securities |  |  | — |  |  |  | 12,780 |  |  |  | — |  |  |  | 12,780 |
U.S. Treasury securities |  |  | 64,804 |  |  |  | — |  |  |  | — |  |  |  | 64,804 |
Total securities available-for-sale—fixed maturity |  |  | 64,804 |  |  |  | 403,215 |  |  |  | — |  |  |  | 468,019 |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Domestic common stock |  |  | 14,789 |  |  |  | — |  |  |  | 2 |  |  |  | 14,791 |
Total |  | $ | 79,593 |  |  | $ | 403,215 |  |  | $ | 2 |  |  | $ | 482,810 |
At December 31, 2017, assets measured at fair value on a recurring basis are summarized below:
|  | December 31, 2017 |
|  | Level 1 Inputs |  |  | Level 2 Inputs |  |  | Level 3 Inputs |  |  | Total Fair Value |
|  | (in thousands) |
Financial instruments carried at fair value, classified as part of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Securities available-for-sale—fixed maturity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
States and political subdivisions |  | $ | — |  |  | $ | 251,140 |  |  | $ | — |  |  | $ | 251,140 |
Corporate bonds |  |  | — |  |  |  | 130,222 |  |  |  | — |  |  |  | 130,222 |
U.S. agency-based mortgage-backed securities |  |  | — |  |  |  | 18,014 |  |  |  | — |  |  |  | 18,014 |
U.S. Treasury securities and obligations of U.S. government agencies |  |  | 66,218 |  |  |  | — |  |  |  | — |  |  |  | 66,218 |
Total securities available-for-sale—fixed maturity |  | $ | 66,218 |  |  | $ | 399,376 |  |  | $ | — |  |  | $ | 465,594 |
Securities available-for-sale—Equity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Domestic common stock |  |  | 9,248 |  |  |  | — |  |  |  | 34 |  |  |  | 9,282 |
Total available-for-sale |  | $ | 75,466 |  |  | $ | 399,376 |  |  | $ | 34 |  |  | $ | 474,876 |
Schedule of Assets Measured at Amortized Cost | At September 30, 2018, assets measured at amortized cost are summarized below:
|  | September 30, 2018 |
|  | Level 1 Inputs |  |  | Level 2 Inputs |  |  | Level 3 Inputs |  |  | Total Fair Value |
|  | (in thousands) |
Securities held-to-maturity—fixed maturity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
States and political subdivisions |  | $ | — |  |  | $ | 428,688 |  |  | $ | — |  |  | $ | 428,688 |
Corporate bonds |  |  | — |  |  |  | 94,861 |  |  |  | — |  |  |  | 94,861 |
U.S. agency-based mortgage-backed securities |  |  | — |  |  |  | 8,807 |  |  |  | — |  |  |  | 8,807 |
U.S. Treasury securities |  |  | 7,057 |  |  |  | — |  |  |  | — |  |  |  | 7,057 |
Obligations of U.S. government agencies |  |  | — |  |  |  | 59,354 |  |  |  | — |  |  |  | 59,354 |
Asset-backed securities |  |  | — |  |  |  | 1,118 |  |  |  | — |  |  |  | 1,118 |
Total held-to-maturity |  | $ | 7,057 |  |  | $ | 592,828 |  |  | $ | — |  |  | $ | 599,885 |
At December 31, 2017, assets measured at amortized cost are summarized below:
|  | December 31, 2017 |
|  | Level 1 Inputs |  |  | Level 2 Inputs |  |  | Level 3 Inputs |  |  | Total Fair Value |
|  | (in thousands) |
Securities held-to-maturity—fixed maturity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
States and political subdivisions |  | $ | — |  |  | $ | 469,101 |  |  | $ | — |  |  | $ | 469,101 |
Corporate bonds |  |  | — |  |  |  | 100,047 |  |  |  | — |  |  |  | 100,047 |
U.S. agency-based mortgage-backed securities |  |  | — |  |  |  | 10,845 |  |  |  | — |  |  |  | 10,845 |
U.S. Treasury securities |  |  | 6,750 |  |  |  | — |  |  |  | — |  |  |  | 6,750 |
Obligations of U.S. government agencies |  |  | — |  |  |  | 51,257 |  |  |  | — |  |  |  | 51,257 |
Asset-backed securities |  |  | — |  |  |  | 1,309 |  |  |  | — |  |  |  | 1,309 |
Total held-to-maturity |  | $ | 6,750 |  |  | $ | 632,559 |  |  | $ | — |  |  | $ | 639,309 |
Summary of Information Regarding Changes in Fair Value of Assets Measured at Fair Value | The following table presents summary information regarding changes in the fair value of assets measured at fair value using Level 3 input.
|  | Nine Months Ended |  |  | Twelve Months Ended |
|  | September 30, 2018 |  |  | December 31, 2017 |
|  | (in thousands) |
Balance, beginning of period |  | $ | 34 |  |  | $ | — |
Transfer into Level 3 |  |  | — |  |  |  | 34 |
Unrealized loss on equity security |  |  | (32 | ) |  |  | — |
Balance, end of period |  | $ | 2 |  |  | $ | 34 |
Summary of Carrying Values and Corresponding Fair Values for Financial Instruments | The following table summarizes the carrying values and corresponding fair values for financial instruments:
|  | As of September 30, 2018 |  |  | As of December 31, 2017 |
|  | Carrying Amount |  |  | Fair Value |  |  | Carrying Amount |  |  | Fair Value |
|  | (in thousands) |
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed maturity securities—held-to-maturity |  | $ | 602,830 |  |  | $ | 599,885 |  |  | $ | 629,668 |  |  | $ | 639,309 |
Fixed maturity securities—available-for-sale |  |  | 468,019 |  |  |  | 468,019 |  |  |  | 465,594 |  |  |  | 465,594 |
Equity securities |  |  | 14,791 |  |  |  | 14,791 |  |  |  | 9,282 |  |  |  | 9,282 |
Short-term investments |  |  | 104,896 |  |  |  | 104,896 |  |  |  | 25,770 |  |  |  | 25,770 |
Cash and cash equivalents |  |  | 33,324 |  |  |  | 33,324 |  |  |  | 55,559 |  |  |  | 55,559 |

X
- Definition Fair value schedule of assets carried at amortized cost. + References No definition available. + Details
Name: | amsf_HeldToMaturitySecuritiesTableTextBlock
Namespace Prefix: | amsf_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19279-110258 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the fair value of financial instruments, including financial assets and financial liabilities, and the measurements of those instruments, assets, and liabilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13467-108611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueByBalanceSheetGroupingTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_FairValueDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19190-110258 + Details
Name: | us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration