Basis of Presentation (Policies)	3 Months Ended
Mar. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation AMERISAFE, Inc. (the “Company”) is an insurance holding company incorporated in the state of Texas. The accompanying unaudited consolidated financial statements include the accounts of AMERISAFE and its subsidiaries: American Interstate Insurance Company (“AIIC”) and its insurance subsidiaries, Silver Oak Casualty, Inc. (“SOCI”) and American Interstate Insurance Company of Texas (“AIICTX”), Amerisafe Risk Services, Inc. (“RISK”) and Amerisafe General Agency, Inc. (“AGAI”). AIIC and SOCI are property and casualty insurance companies organized under the laws of the state of Nebraska. AIICTX is a property and casualty insurance company organized under the laws of the state of Texas. RISK, a wholly owned subsidiary of the Company, is a claims and safety service company currently servicing only affiliated insurance companies. AGAI, a wholly owned subsidiary of the Company, is a general agent for the Company. AGAI sells insurance, which is underwritten by AIIC, SOCI and AIICTX, as well as by nonaffiliated insurance carriers. The assets and operations of AGAI are not significant to that of the Company and its consolidated subsidiaries. The terms “AMERISAFE,” the “Company,” “we,” “us” or “our” refer to AMERISAFE, Inc. and its consolidated subsidiaries, as the context requires. The Company provides workers’ compensation insurance for small to mid-sized employers engaged in hazardous industries, principally construction, trucking, logging and lumber, manufacturing, agriculture, maritime, and oil and gas. Assets and revenues of AIIC and its subsidiaries represent at least 95 % of comparable consolidated amounts of the Company for each of the three months ended March 31, 2020 and 2019. In the opinion of management of the Company, the accompanying unaudited consolidated financial statements contain all adjustments (consisting of normal recurring accruals) necessary to present fairly the financial position, the results of operations and cash flows for the periods presented. The unaudited consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q under the Securities Exchange Act of 1934 and therefore do not include all information and footnotes to be in conformity with accounting principles generally accepted in the United States (“GAAP”). The results for the interim periods are not necessarily indicative of the results of operations that may be expected for the year. The unaudited consolidated financial statements contained herein should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2019. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of our assets, liabilities, revenues and expenses and related disclosures. Some of the estimates result from judgments that can be subjective and complex and, consequently, actual results in future periods might differ from these estimates.
Adopted Accounting Guidance	Adopted Accounting Guidance On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses (“CECL”). The prior guidance delays the recognition of credit losses until a probable loss has occurred. The new guidance requires credit losses for securities measured at amortized cost to be determined using current expected credit loss estimates. These estimates are derived from historical, current and reasonable supporting forecasts, including prepayments and estimates, and are recorded through a valuation account. The same method is used for available-for-sale securities, but the valuation account is limited to the amount by which the fair value is below amortized cost. The Company implemented the new standard using the modified retrospective approach. Results for reporting periods beginning after January 1, 2020 are presented under the new guidance while prior period amounts continue to be reported in accordance with previously applicable GAAP. The Company recorded a net decrease to Retained Earnings of $594 thousand as of January 1, 2020, for the cumulative effect of adopting ASU 2016-13. The transition adjustment includes a $243 thousand impact to establish a credit loss allowance for held-to-maturity securities. The remaining $351 thousand of the transition adjustment was due to the creation of the reinsurance recoverable credit allowance. The Company believes that under the standard there is no current expected credit allowance necessary for U.S. Government Securities in its judgment as: 1) Treasury securities typically are the most highly rated securities among rating agencies; 2) Treasury securities have a long history of no credit losses; 3) Treasury securities are guaranteed by a sovereign entity (the U.S. Government) that can print its own money and whose currency (the U.S. dollar) is the reserve currency. The Company believes that under the standard there is no current expected credit allowance necessary for GNMA Securities in its judgment as: 1) GNMA securities typically are the most highly rated securities among rating agencies; 2) GNMA securities have a long history of no credit losses and payments are explicitly guaranteed by the United States; 3) Underlying mortgage loans for GNMA securities are insured by the Federal Housing Administration or guaranteed by the U.S. Department of Veteran Affairs; 4) the U.S. Government can print its own money to retire GNMA obligations. The Company believes that under the standard there is no current expected credit allowance necessary for FNMA or Freddie Mac (FHLMC) Securities in its judgment as: 1) These securities typically are among the most highly rated securities among rating agencies; 2) There is a long history of no credit losses; 3) Principal and interest payments are guaranteed by the issuing agency; 4) There is an explicit guarantee by the U.S. Government that can print its own money and whose currency (the U.S. dollar) is the reserve currency. The Company researched various options and methodologies and has chosen to use Moody’s default rates and recovery rates for our held-to-maturity fixed income securities based on the current credit rating of the security and the time period to the stated maturity date. This is a probability of default (PD) and loss given default (LGD) methodology. The credit rating used for held-to-maturity fixed income securities is the rating for each security as published by Moody’s, S&P, and Fitch to determine the probability of default. If there are two ratings, the lower rating is used. If there are three ratings, the median rating is used. If there is one rating, that rating is used. This methodology provides additional conservatism in determining the credit loss allowance needed. For corporate fixed income securities, the probability of default (given a rating) comes from Moody’s annual study of Corporate Bond defaults published each February. This study also contains the average recovery rates based on the historical defaults in the Moody’s study. We have chosen to use the 1983-2018 data as more reflective of the current historical pattern of defaults (the study goes back to 1920). The maximum maturity using the default rate is 20 years (any maturity greater than 20 years will use the 20-year rate). For municipal fixed income securities the probability of default (given a rating) comes from Moody’s annual study of Municipal Bond defaults published each July/August. This study also contains the average recovery rates based on the historical defaults in the Moody’s study. This study covers 1970-2018 data, which we believe is reflective of the current historical pattern of defaults. The maximum maturity using the default rate is 20 years (any maturity greater than 20 years will use the 20-year rate). The Company did not record a credit allowance for available-for-sale securities. The available-for-sale portfolio is composed of highly rated securities, which carry a low risk of default. The Company’s concentrations in municipal bonds have helped lower default risk, as the historical default rates and recovery rates for municipal bonds has been much better than corporate bonds rated at the same level. The Company creates a watch list of available-for-sale securities that are below book value at the end of each quarter. This watch list excludes US Treasury securities, GNMA Securities, and government agency securities (FNMA, etc.) as none of those securities will have an expected credit loss. The watch list will also exclude those securities that are trading at least at $95 or above (par value $100) as the Company believes any slight difference between $95 and par likely reflect interest rate changes and liquidity only and are not a sign of credit impairment or market expectations for any current expected credit loss. The list is reviewed by the Management Investment Committee to evaluate any security where the discounted cash flows expected no longer exceed the book value of the security. If the Company intends to sell the security (or more likely than not be required to sell the security before recovery of the loss) the Company will write down the security to fair value through earnings. If the Company intends to hold the security, the Company will establish a credit loss allowance for the security through earnings, and adjust the allowance each quarter through earnings, as the security changes in value. In determining the amount the credit loss allowance, the Company will consider all of the following factors: 1. The extent to which the fair value is less than the amortized cost basis 2. Adverse conditions in the security, industry, or geography, including: a.) Changes in technology b.) Discontinuation of a segment of business that may affect future earnings c.) Changes in the quality of the credit enhancement, if any 3. Changes in the payment structure of the debt security 4. Failure of the issuer to make scheduled interest or principal payments 5. Any changes to the rating of the security by a rating agency The calculation of the credit loss allowance will not take into account the amount of time the security has been below book value or when the security might be expected to recover in value. The Company has researched various options and methodologies and has chosen to use Moody’s default rates and recovery rates for our unsecured reinsurance recoverables based on the current credit rating of the reinsurer and a time period of ten years. This is a probability of default (PD) and loss given default (LGD) methodology. The ten-year period is consistent with our current working layer reinsurance treaty where we have a three-year treaty, which must be commuted by the end of the tenth year. We believe this is an appropriate approach to our reinsurance recoverables. The credit rating used for reinsurance recoverables uses the average rating for each reinsurer as published by Moody’s, S&P, Fitch and A.M. Best to determine the probability of default. The median rating is used if there are three ratings. The probability of default (given a rating) comes from Moody’s annual study of Corporate Bond defaults published each February. This study also contains the average recovery rates based on the historical defaults in the Moody’s study. We have chosen to use the 1983-2018 data as more reflective of the current historical pattern of defaults (the study goes back to 1920). The Company does not hold any debt securities for which an other-than-temporary impairment has been recognized. Additionally, the Company does not hold any financial assets purchased with credit deterioration. The Company’s internal working group evaluated the existing allowance for doubtful accounts reserving methodology for premiums receivable and determined the calculation was consistent with the new credit loss guidance. There was no impact to the premiums receivable balance as a result of the adoption of the new standard. The Company has elected not to establish a credit allowance for interest receivable. The Company plans to continue use of the current policy for writing off balances receivable over ninety days old.
Prospective Accounting Guidance	Prospective Accounting Guidance All issued but not yet effective accounting and reporting standards as of March 31, 2020 are either not applicable to the Company or are not expected to have a material impact on the Company.
Fair Value Measurements	The Company carries available-for-sale securities at fair value in our consolidated financial statements and determines fair value measurements and disclosure in accordance with FASB ASC Topic 820, Fair Value Measurements and Disclosures. The Company determines the fair values of its financial instruments based on the fair value hierarchy established in ASC Topic 820, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard defines fair value, describes three levels of inputs that may be used to measure fair value, and expands disclosures about fair value measurements.

Basis of Presentation (Policies)

3 Months Ended

Mar. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

AMERISAFE, Inc. (the “Company”) is an insurance holding company incorporated in the state of Texas. The accompanying unaudited consolidated financial statements include the accounts of AMERISAFE and its subsidiaries: American Interstate Insurance Company (“AIIC”) and its insurance subsidiaries, Silver Oak Casualty, Inc. (“SOCI”) and American Interstate Insurance Company of Texas (“AIICTX”), Amerisafe Risk Services, Inc. (“RISK”) and Amerisafe General Agency, Inc. (“AGAI”). AIIC and SOCI are property and casualty insurance companies organized under the laws of the state of Nebraska. AIICTX is a property and casualty insurance company organized under the laws of the state of Texas. RISK, a wholly owned subsidiary of the Company, is a claims and safety service company currently servicing only affiliated insurance companies. AGAI, a wholly owned subsidiary of the Company, is a general agent for the Company. AGAI sells insurance, which is underwritten by AIIC, SOCI and AIICTX, as well as by nonaffiliated insurance carriers. The assets and operations of AGAI are not significant to that of the Company and its consolidated subsidiaries.

The terms “AMERISAFE,” the “Company,” “we,” “us” or “our” refer to AMERISAFE, Inc. and its consolidated subsidiaries, as the context requires.

The Company provides workers’ compensation insurance for small to mid-sized employers engaged in hazardous industries, principally construction, trucking, logging and lumber, manufacturing, agriculture, maritime, and oil and gas. Assets and revenues of AIIC and its subsidiaries represent at least 95 % of comparable consolidated amounts of the Company for each of the three months ended March 31, 2020 and 2019.

In the opinion of management of the Company, the accompanying unaudited consolidated financial statements contain all adjustments (consisting of normal recurring accruals) necessary to present fairly the financial position, the results of operations and cash flows for the periods presented. The unaudited consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q under the Securities Exchange Act of 1934 and therefore do not include all information and footnotes to be in conformity with accounting principles generally accepted in the United States (“GAAP”). The results for the interim periods are not necessarily indicative of the results of operations that may be expected for the year. The unaudited consolidated financial statements contained herein should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2019.

The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of our assets, liabilities, revenues and expenses and related disclosures. Some of the estimates result from judgments that can be subjective and complex and, consequently, actual results in future periods might differ from these estimates.

Adopted Accounting Guidance

On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses (“CECL”). The prior guidance delays the recognition of credit losses until a probable loss has occurred. The new guidance requires credit losses for securities measured at amortized cost to be determined using current expected credit loss estimates. These estimates are derived from historical, current and reasonable supporting forecasts, including prepayments and estimates, and are recorded through a valuation account. The same method is used for available-for-sale securities, but the valuation account is limited to the amount by which the fair value is below amortized cost.

The Company implemented the new standard using the modified retrospective approach. Results for reporting periods beginning after January 1, 2020 are presented under the new guidance while prior period amounts continue to be reported in accordance with previously applicable GAAP. The Company recorded a net decrease to Retained Earnings of $594 thousand as of January 1, 2020, for the cumulative effect of adopting ASU 2016-13. The transition adjustment includes a $243 thousand impact to establish a credit loss allowance for held-to-maturity securities. The remaining $351 thousand of the transition adjustment was due to the creation of the reinsurance recoverable credit allowance.

The Company believes that under the standard there is no current expected credit allowance necessary for U.S. Government Securities in its judgment as: 1) Treasury securities typically are the most highly rated securities among rating agencies; 2) Treasury securities have a long history of no credit losses; 3) Treasury securities are guaranteed by a sovereign entity (the U.S. Government) that can print its own money and whose currency (the U.S. dollar) is the reserve currency.

The Company believes that under the standard there is no current expected credit allowance necessary for GNMA Securities in its judgment as: 1) GNMA securities typically are the most highly rated securities among rating agencies; 2) GNMA securities have a long history of no credit losses and payments are explicitly guaranteed by the United States; 3) Underlying mortgage loans for GNMA securities are insured by the Federal Housing Administration or guaranteed by the U.S. Department of Veteran Affairs; 4) the U.S. Government can print its own money to retire GNMA obligations.

The Company believes that under the standard there is no current expected credit allowance necessary for FNMA or Freddie Mac (FHLMC) Securities in its judgment as: 1) These securities typically are among the most highly rated securities among rating agencies; 2) There is a long history of no credit losses; 3) Principal and interest payments are guaranteed by the issuing agency; 4) There is an explicit guarantee by the U.S. Government that can print its own money and whose currency (the U.S. dollar) is the reserve currency.

The Company researched various options and methodologies and has chosen to use Moody’s default rates and recovery rates for our held-to-maturity fixed income securities based on the current credit rating of the security and the time period to the stated maturity date. This is a probability of default (PD) and loss given default (LGD) methodology.

The credit rating used for held-to-maturity fixed income securities is the rating for each security as published by Moody’s, S&P, and Fitch to determine the probability of default. If there are two ratings, the lower rating is used. If there are three ratings, the median rating is used. If there is one rating, that rating is used. This methodology provides additional conservatism in determining the credit loss allowance needed.

For corporate fixed income securities, the probability of default (given a rating) comes from Moody’s annual study of Corporate Bond defaults published each February. This study also contains the average recovery rates based on the historical defaults in the Moody’s study. We have chosen to use the 1983-2018 data as more reflective of the current historical pattern of defaults (the study goes back to 1920). The maximum maturity using the default rate is 20 years (any maturity greater than 20 years will use the 20-year rate).

For municipal fixed income securities the probability of default (given a rating) comes from Moody’s annual study of Municipal Bond defaults published each July/August. This study also contains the average recovery rates based on the historical defaults in the Moody’s study. This study covers 1970-2018 data, which we believe is reflective of the current historical pattern of defaults. The maximum maturity using the default rate is 20 years (any maturity greater than 20 years will use the 20-year rate).

The Company did not record a credit allowance for available-for-sale securities. The available-for-sale portfolio is composed of highly rated securities, which carry a low risk of default. The Company’s concentrations in municipal bonds have helped lower default risk, as the historical default rates and recovery rates for municipal bonds has been much better than corporate bonds rated at the same level. The Company creates a watch list of available-for-sale securities that are below book value at the end of each quarter. This watch list excludes US Treasury securities, GNMA Securities, and government agency securities (FNMA, etc.) as none of those securities will have an expected credit loss. The watch list will also exclude those securities that are trading at least at $95 or above (par value $100) as the Company believes any slight difference between $95 and par likely reflect interest rate changes and liquidity only and are not a sign of credit impairment or market expectations for any current expected credit loss.

The list is reviewed by the Management Investment Committee to evaluate any security where the discounted cash flows expected no longer exceed the book value of the security. If the Company intends to sell the security (or more likely than not be required to sell the security before recovery of the loss) the Company will write down the security to fair value through earnings. If the Company intends to hold the security, the Company will establish a credit loss allowance for the security through earnings, and adjust the allowance each quarter through earnings, as the security changes in value.

In determining the amount the credit loss allowance, the Company will consider all of the following factors:

1. The extent to which the fair value is less than the amortized cost basis

2. Adverse conditions in the security, industry, or geography, including:

a.) Changes in technology

b.) Discontinuation of a segment of business that may affect future earnings

c.) Changes in the quality of the credit enhancement, if any

3. Changes in the payment structure of the debt security

4. Failure of the issuer to make scheduled interest or principal payments

5. Any changes to the rating of the security by a rating agency

The calculation of the credit loss allowance will not take into account the amount of time the security has been below book value or when the security might be expected to recover in value.

The Company has researched various options and methodologies and has chosen to use Moody’s default rates and recovery rates for our unsecured reinsurance recoverables based on the current credit rating of the reinsurer and a time period of ten years. This is a probability of default (PD) and loss given default (LGD) methodology. The ten-year period is consistent with our current working layer reinsurance treaty where we have a three-year treaty, which must be commuted by the end of the tenth year. We believe this is an appropriate approach to our reinsurance recoverables.

The credit rating used for reinsurance recoverables uses the average rating for each reinsurer as published by Moody’s, S&P, Fitch and A.M. Best to determine the probability of default. The median rating is used if there are three ratings. The probability of default (given a rating) comes from Moody’s annual study of Corporate Bond defaults published each February. This study also contains the average recovery rates based on the historical defaults in the Moody’s study. We have chosen to use the 1983-2018 data as more reflective of the current historical pattern of defaults (the study goes back to 1920).

The Company does not hold any debt securities for which an other-than-temporary impairment has been recognized. Additionally, the Company does not hold any financial assets purchased with credit deterioration.

The Company’s internal working group evaluated the existing allowance for doubtful accounts reserving methodology for premiums receivable and determined the calculation was consistent with the new credit loss guidance. There was no impact to the premiums receivable balance as a result of the adoption of the new standard.

The Company has elected not to establish a credit allowance for interest receivable. The Company plans to continue use of the current policy for writing off balances receivable over ninety days old.

Prospective Accounting Guidance

All issued but not yet effective accounting and reporting standards as of March 31, 2020 are either not applicable to the Company or are not expected to have a material impact on the Company.

Fair Value Measurements

The Company carries available-for-sale securities at fair value in our consolidated financial statements and determines fair value measurements and disclosure in accordance with FASB ASC Topic 820, Fair Value Measurements and Disclosures.

The Company determines the fair values of its financial instruments based on the fair value hierarchy established in ASC Topic 820, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard defines fair value, describes three levels of inputs that may be used to measure fair value, and expands disclosures about fair value measurements.