AMERISAFE (AMSF) 10-Q 27 Apr 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 25, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	AMSF
Entity Registrant Name	AMERISAFE INC
Entity Central Index Key	1,018,979
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		19,260,915

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investments:
Fixed maturity securities—held-to-maturity, at amortized cost (fair value $620,936 and $639,309 in 2018 and 2017, respectively)	$ 619,400	$ 629,668
Fixed maturity securities—available-for-sale, at fair value (cost $462,033 and $461,236 in 2018 and 2017, respectively)	459,264	465,594
Equity securities—available-for-sale, at fair value (cost $11,425 and $8,503 in 2018 and 2017, respectively)	11,425	9,282
Short-term investments	44,704	25,770
Total investments	1,134,793	1,130,314
Cash and cash equivalents	36,072	55,559
Amounts recoverable from reinsurers	94,173	90,133
Premiums receivable, net of allowance	186,798	174,234
Deferred income taxes	20,499	19,262
Accrued interest receivable	11,332	10,635
Property and equipment, net	6,774	6,128
Deferred policy acquisition costs	21,287	20,251
Federal income tax recoverable		1,761
Other assets	18,937	9,959
Total assets	1,530,665	1,518,236
Liabilities:
Reserves for loss and loss adjustment expenses	777,298	771,845
Unearned premiums	164,972	157,270
Amounts held for others	37,343	36,908
Policyholder deposits	48,331	48,364
Insurance-related assessments	28,389	28,246
Federal income tax payable	1,387
Accounts payable and other liabilities	37,767	37,076
Payable for investments purchased	3,110	13,104
Total liabilities	1,098,597	1,092,813
Shareholders’ equity:
Common stock: voting—$0.01 par value authorized shares—50,000,000 in 2018 and 2017; 20,519,165 and 20,504,165 shares issued and 19,260,915 and 19,245,915 shares outstanding in 2018 and 2017, respectively	205	204
Additional paid-in capital	210,441	210,081
Treasury stock at cost (1,258,250 shares in 2018 and 2017)	(22,370)	(22,370)
Accumulated earnings	246,028	233,896
Accumulated other comprehensive income (loss), net	(2,236)	3,612
Total shareholders’ equity	432,068	425,423
Total liabilities and shareholders’ equity	$ 1,530,665	$ 1,518,236

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Fixed maturity securities, fair value	$ 620,936	$ 639,309
Fixed maturity securities, cost	462,033	461,236
Equity securities, cost	$ 11,425	$ 8,503
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	20,519,165	20,504,165
Common stock, shares outstanding	19,260,915	19,245,915
Treasury stock, shares	1,258,250	1,258,250

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Gross premiums written	$ 97,342	$ 95,078
Ceded premiums written	(2,330)	(2,391)
Net premiums written	95,012	92,687
Net premiums earned	87,310	90,912
Net investment income	7,209	6,710
Net realized losses on investments	(31)	(181)
Net unrealized losses on equity securities	(390)
Fee and other income	77	101
Total revenues	94,175	97,542
Expenses
Loss and loss adjustment expenses incurred	53,162	56,216
Underwriting and certain other operating costs	7,846	8,500
Commissions	6,494	6,410
Salaries and benefits	5,926	6,312
Policyholder dividends	1,333	1,371
Total expenses	74,761	78,809
Income before income taxes	19,414	18,733
Income tax expense	3,245	5,209
Net income	$ 16,169	$ 13,524
Earnings per share
Basic	$ 0.84	$ 0.71
Diluted	$ 0.84	$ 0.70
Shares used in computing earnings per share
Basic	19,187,136	19,150,400
Diluted	19,262,237	19,230,125
Cash dividends declared per common share	$ 0.22	$ 0.20

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 16,169	$ 13,524
Other comprehensive income:
Unrealized gain (loss) on securities, net of tax	[1]	(5,848)	952
Comprehensive income		$ 10,321	$ 14,476
[1]	Data presented for 2018 includes debt securities only compared to 2017 which includes both debt and equity securities.

Condensed Consolidated Stateme6

Condensed Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2016						$ (492)
Comprehensive income	$ 14,476
Common stock issued upon exercise of options, Shares	0
Ending Balance at Mar. 31, 2017						460
Beginning Balance at Dec. 31, 2017	$ 425,423	$ 204	$ 210,081	$ (22,370)	$ 233,896	3,612
Beginning Balance, Shares at Dec. 31, 2017	20,504,165	20,504,165
Treasury Stock Beginning Balance, Shares at Dec. 31, 2017	(1,258,250)			(1,258,250)
Comprehensive income	$ 10,321				16,169	(5,848)
Impact of adoption of ASU | ASU 2016-01 [Member]	615				615
Impact of adoption of ASU | ASU 2018-02 [Member]	(414)				(414)
Common stock issued upon exercise of options	$ 68	$ 1	67
Common stock issued upon exercise of options, Shares	15,000	15,000
Share-based compensation	$ 293		293
Dividends to shareholders	(4,238)				(4,238)
Ending Balance at Mar. 31, 2018	$ 432,068	$ 205	$ 210,441	$ (22,370)	$ 246,028	$ (2,236)
Ending Balance, Shares at Mar. 31, 2018	20,519,165	20,519,165
Treasury Stock Ending Balance, Shares at Mar. 31, 2018	(1,258,250)			(1,258,250)

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net income	$ 16,169	$ 13,524
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	222	266
Net amortization of investments	3,151	3,769
Deferred income taxes	264	(13)
Net realized losses on investments	31	181
Net unrealized losses on equity securities	390
Net realized losses on disposal of assets		2
Share-based compensation	18	416
Changes in operating assets and liabilities:
Premiums receivable, net	(12,564)	(8,271)
Accrued interest receivable	(697)	(547)
Deferred policy acquisition costs	(1,036)	(566)
Amounts held by others	(7,855)
Other assets	2,438	(1,148)
Reserves for loss and loss adjustment expenses	5,453	6,720
Unearned premiums	7,702	1,775
Reinsurance balances	(4,040)	741
Amounts held for others and policyholder deposits	402	414
Accounts payable and other liabilities	2,618	6,531
Net cash provided by operating activities	12,666	23,794
Investing activities
Purchases of investments held-to-maturity	(17,925)	(53,640)
Purchases of investments available-for-sale	(28,510)	(34,081)
Purchases of short-term investments	(28,688)	(4,907)
Proceeds from maturities of investments held-to-maturity	19,127	19,752
Proceeds from sales and maturities of investments available-for-sale	25,004	29,851
Proceeds from sales and maturities of short-term investments	4,000	1,630
Proceeds from redemptions of other investments		2,000
Purchases of property and equipment	(868)	(73)
Net cash used in investing activities	(27,860)	(39,468)
Financing activities
Proceeds from stock option exercises	68
Dividends to shareholders	(4,361)	(3,909)
Net cash used in financing activities	(4,293)	(3,909)
Change in cash and cash equivalents	(19,487)	(19,583)
Cash and cash equivalents at beginning of period	55,559	58,936
Cash and cash equivalents at end of period	$ 36,072	$ 39,353

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	Note 1. Basis of Presentation AMERISAFE, Inc. (the “Company”) is an insurance holding company incorporated in the state of Texas. The accompanying unaudited condensed 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, and agriculture. Assets and revenues of AIIC represent at least 95% of comparable consolidated amounts of the Company for each of the three months ended March 31, 2018 and 2017. In the opinion of management of the Company, the accompanying unaudited condensed 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 condensed 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 condensed consolidated financial statements contained herein should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2017. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Adopted Accounting Guidance In January 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. This guidance requires fair value measurement for equity investments (not including those that result in consolidation of the investee or use the equity method of accounting) and the recognition of changes in fair value to be presented as a component of net income. The guidance also revises the disclosure requirements related to fair value changes of liabilities presented in comprehensive income, eliminates disclosure related to the methods and assumptions underlying fair value for financial instruments measured at amortized cost, and simplifies impairment assessments for equity investments without readily determinable fair values. The adoption of this new guidance in the first quarter of 2018 resulted in an immaterial decrease in net income of $390 thousand or a $0.02 decrease in our diluted earnings per common share. In May 2014, the FASB issued ASU 2014-09 (Topic 606): Revenue from Contract s In February 2018, the FASB issued ASU 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220). This ASU provided new guidance on reclassification from Other Comprehensive Income (“OCI”) of tax effects related to recently passed tax reform legislation. The guidance gives entities the option to reclassify to retained earnings tax effects related to items in accumulated OCI deemed to be stranded as a result of tax reform. The guidance was effective for us in the first quarter of 2018 and was applied retrospectively. The Company’s policy for releasing income tax effects from accumulated OCI was the individual securities approach for available-for-sale securities. The adoption of this guidance did not have a material impact on our financial condition and results of operations. In December 2017, the SEC issued Staff Accounting Bulletin (SAB) 118 which provided guidance on accounting for tax effects of the Tax Act. Among many changes of the Tax Act which affected Property and Casualty Insurers, the Tax Act required property and casualty taxpayers to discount loss reserves based solely on IRS factors and no longer by reference to historical payment patterns. As the IRS has yet to release the 2018 discount factors, we have used the 2017 IRS discount factors to estimate the impact of the change in loss reserve discounting factors and have adjusted our deferred tax balances at March 31, 2018 for the impact of these changes. As prescribed by SAB 118, we continue to utilize the discount factors based on existing accounting guidance and the provisions of the tax laws that were in effect immediately prior to enactment of the Tax Act. Once the IRS has released the 2018 loss reserve discount factors, we will complete our analysis and include the effect of the difference in the reserve discount factors in the period the analysis is complete or the impact is reasonably estimable. Prospective Accounting Guidance In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). Under current guidance for lessees, leases are only included on the balance sheet if certain criteria, classifying the contract as a capital lease, are met. The new guidance requires a lessee to recognize a lease liability and a right of use asset for all leases extending beyond twelve months. The new guidance is effective for us in the first quarter of 2019. Upon adoption, leases will be recognized and measured at the beginning of the earliest period presented using a modified retrospective approach. Adoption of the guidance is not expected to have a material effect on the Company’s consolidated financial statements as the Company does not have any significant leases. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses. The new guidance replaces the methodology of credit loss impairment, which currently, delays the recognition of credit losses until a probable loss has been incurred. The new guidance requires credit losses for securities measured at amortized cost to be determined using current expected credit loss estimates. These estimates are to be derived from historical, current and reasonable supporting forecasts, including prepayments and estimates, and will be recorded through a valuation allowance account that will run through the income statement. The same method will be used for available-for-sale securities, but the valuation allowance will be limited to the amount by which the fair value is below amortized cost. The standard is effective for us in the first quarter of 2020. The Company will continue to monitor and evaluate the impact as the implementation date approaches. All other issued but not yet effective accounting and reporting standards as of March 31, 2018 are either not applicable to the Company or are not expected to have a material impact on the Company.

Stock Options and Restricted St

Stock Options and Restricted Stock	3 Months Ended
	Mar. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options and Restricted Stock	Note 2. Stock Options and Restricted Stock As of March 31, 2018, the Company has three equity incentive plans: the AMERISAFE 2005 Equity Incentive Plan (the “2005 Incentive Plan”), the AMERISAFE Non-Employee Director Restricted Stock Plan (the “Restricted Stock Plan”) and the AMERISAFE 2012 Equity and Incentive Compensation Plan (the “2012 Incentive Plan”). In connection with the approval of the 2012 Incentive Plan by the Company’s shareholders, no further grants will be made under the 2005 Incentive Plan. All grants made under the 2005 Incentive plan continue in effect, subject to the terms and conditions of the 2005 Incentive Plan. See Note 12 to our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2017 for additional information regarding the Company’s incentive plans. During the three months ended March 31, 2018, options to purchase 15,000 shares of common stock were exercised. In connection with these exercises, the Company received $ 0.1 million of stock option proceeds. During the three months ended March 31, 2017, no options to purchase shares of common stock were exercised. The Company recognized share-based compensation expense of $18,000 in the three months ended March 31, 2018 and $0.4 million for the same period of 2017.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Note 3. Earnings Per Share The Company computes earnings per share (“EPS”) in accordance with FASB Accounting Standards Codification (“ASC”) Topic 260, Earnings Per Share Basic EPS is calculated by dividing net income by the weighted-average number of common shares outstanding during the period. The diluted EPS calculation includes potential common shares assumed issued under the treasury stock method, which reflects the potential dilution that would occur if any outstanding options were exercised or restricted stock becomes vested. Three Months Ended March 31, 2018 2017 (in thousands, except share and per share amounts) Basic EPS Net income - basic $ 16,169 $ 13,524 Basic weighted average common shares 19,187,136 19,150,400 Basic earnings per common share $ 0.84 $ 0.71 Diluted EPS Net income - diluted $ 16,169 $ 13,524 Diluted weighted average common shares: Weighted average common shares 19,187,136 19,150,400 Stock options and restricted stock 75,101 79,725 Diluted weighted average common shares 19,262,237 19,230,125 Diluted earnings per common share $ 0.84 $ 0.70

Investments

Investments	3 Months Ended
	Mar. 31, 2018
Investments Debt And Equity Securities [Abstract]
Investments	Note 4. Investments The gross unrealized gains and losses on, and the amortized cost and fair value of, those investments classified as held-to-maturity at March 31, 2018 are summarized as follows: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) States and political subdivisions $ 450,553 $ 5,041 $ (3,248 ) $ 452,346 Corporate bonds 99,368 29 (650 ) 98,747 U.S. agency-based mortgage-backed securities 9,400 503 (72 ) 9,831 U.S. Treasury securities and obligations of U.S. government agencies 58,857 456 (542 ) 58,771 Asset-backed securities 1,222 26 (7 ) 1,241 Totals $ 619,400 $ 6,055 $ (4,519 ) $ 620,936 The gross unrealized gains and losses on, and the cost or amortized cost and fair value of, those investments classified as available-for-sale at March 31, 2018 are summarized as follows: Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Fixed maturity: States and political subdivisions $ 232,778 $ 3,730 $ (2,410 ) $ 234,098 Corporate bonds 143,712 5 (943 ) 142,774 U.S. agency-based mortgage-backed securities 18,260 — (1,275 ) 16,985 U.S. Treasury securities and obligations of U.S. government agencies 67,283 — (1,876 ) 65,407 Total fixed maturity 462,033 3,735 (6,504 ) 459,264 Equity securities 11,425 — — 11,425 Totals $ 473,458 $ 3,735 $ (6,504 ) $ 470,689 The gross unrealized gains and losses on, and the amortized cost and fair value of, those investments classified as held-to-maturity at December 31, 2017 are summarized as follows: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) States and political subdivisions $ 460,428 $ 9,628 $ (955 ) $ 469,101 Corporate bonds 100,024 190 (167 ) 100,047 U.S. agency-based mortgage-backed securities 10,260 625 (40 ) 10,845 U.S. Treasury securities and obligations of U.S. government agencies 57,657 548 (198 ) 58,007 Asset-backed securities 1,299 25 (15 ) 1,309 Totals $ 629,668 $ 11,016 $ (1,375 ) $ 639,309 The gross unrealized gains and losses on, and the cost or amortized cost and fair value of, those investments classified as available-for-sale at December 31, 2017 are summarized as follows: Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Fixed maturity: States and political subdivisions $ 244,898 $ 6,819 $ (577 ) $ 251,140 Corporate bonds 130,210 224 (212 ) 130,222 U.S. agency-based mortgage-backed securities 18,813 — (799 ) 18,014 U.S. Treasury securities and obligations of U.S. government agencies 67,315 29 (1,126 ) 66,218 Total fixed maturity 461,236 7,072 (2,714 ) 465,594 Equity securities 8,503 779 — 9,282 Totals $ 469,739 $ 7,851 $ (2,714 ) $ 474,876 A summary of the amortized cost and fair value of investments in fixed maturity securities, classified as held-to-maturity at March 31, 2018, by contractual maturity, is as follows: Amortized Cost Fair Value (in thousands) Maturity: Within one year $ 97,545 $ 97,835 After one year through five years 255,343 255,678 After five years through ten years 94,872 95,139 After ten years 161,018 161,212 U.S. agency-based mortgage-backed securities 9,400 9,831 Asset-backed securities 1,222 1,241 Totals $ 619,400 $ 620,936 A summary of the amortized cost and fair value of investments in fixed maturity securities, classified as available-for-sale at March 31, 2018, by contractual maturity, is as follows: Amortized Cost Fair Value (in thousands) Maturity: Within one year $ 71,596 $ 71,476 After one year through five years 164,449 162,658 After five years through ten years 38,945 38,371 After ten years 168,783 169,774 U.S. agency-based mortgage-backed securities 18,260 16,985 Totals $ 462,033 $ 459,264 The following table summarizes the fair value and gross unrealized losses on securities, aggregated by major investment category and length of time that the individual securities have been in a continuous unrealized loss position: Less Than 12 Months 12 Months or Greater Total Fair Value of Investments with Unrealized Losses Gross Unrealized Losses Fair Value of Investments with Unrealized Losses Gross Unrealized Losses Fair Value of Investments with Unrealized Losses Gross Unrealized Losses (in thousands) March 31, 2018 Held-to-Maturity Fixed maturity securities: States and political subdivisions $ 212,693 $ 2,810 $ 14,513 $ 438 $ 227,206 $ 3,248 Corporate bonds 89,227 629 2,259 21 91,486 650 U.S. agency-based mortgage-backed securities 2,613 72 — — 2,613 72 U.S. Treasury securities and obligations of U.S. government agencies 48,489 439 4,468 103 52,957 542 Asset-backed securities 535 5 47 2 582 7 Total held-to-maturity securities 353,557 3,955 21,287 564 374,844 4,519 Available-for Sale Fixed maturity securities: States and political subdivisions $ 89,896 $ 1,620 $ 8,892 $ 790 $ 98,788 $ 2,410 Corporate bonds 138,600 943 — — 138,600 943 U.S. agency-based mortgage-backed securities 14,477 451 2,508 824 16,985 1,275 U.S. Treasury securities and obligations of U.S. government agencies 25,022 713 40,385 1,163 65,407 1,876 Total available-for-sale securities 267,995 3,727 51,785 2,777 319,780 6,504 Total $ 621,552 $ 7,682 $ 73,072 $ 3,341 $ 694,624 $ 11,023 Less Than 12 Months 12 Months or Greater Total Fair Value of Investments with Unrealized Losses Gross Unrealized Losses Fair Value of Investments with Unrealized Losses Gross Unrealized Losses Fair Value of Investments with Unrealized Losses Gross Unrealized Losses (in thousands) December 31, 2017 Held-to-Maturity Fixed maturity securities: States and political subdivisions $ 110,698 $ 654 $ 19,895 $ 301 $ 130,593 $ 955 Corporate bonds 56,425 156 4,121 11 60,546 167 U.S. agency-based mortgage-backed securities 2,798 40 — — 2,798 40 U.S. Treasury securities and obligations of U.S. government agencies 48,153 122 3,948 76 52,101 198 Asset-backed securities — — 967 15 967 15 Total held-to-maturity securities 218,074 972 28,931 403 247,005 1,375 Available-for Sale Fixed maturity securities: States and political subdivisions $ 23,365 $ 86 $ 19,153 $ 491 $ 42,518 $ 577 Corporate bonds 82,795 171 5,888 41 88,683 212 U.S. agency-based mortgage-backed securities 14,686 59 3,328 740 18,014 799 U.S. Treasury securities and obligations of U.S. government agencies 14,730 204 47,716 922 62,446 1,126 Total available-for-sale securities 135,576 520 76,085 2,194 211,661 2,714 Total $ 353,650 $ 1,492 $ 105,016 $ 2,597 $ 458,666 $ 4,089 At March 31, 2018, the Company held 448 individual fixed maturity securities that were in an unrealized loss position, of which 44 individual fixed maturity securities were in a continuous unrealized loss position for longer than 12 months. Investment income is recognized as it is earned. The discount or premium on fixed maturity securities is amortized using the “constant yield” method. Anticipated prepayments, where applicable, are considered when determining the amortization of premiums or discounts. Realized investment gains and losses are determined using the specific identification method. We regularly review our investment portfolio to evaluate the necessity of recording impairment losses for other-than-temporary declines in the fair value of specific investments. We consider various factors in determining if a decline in the fair value of an individual security is other-than-temporary. The key factors we consider are: • any reduction or elimination of preferred dividends, or nonpayment of scheduled principal or interest payments; • the financial condition and near-term prospects of the issuer of the applicable security, including any specific events that may affect its operations or earnings; • how long and by how much the fair value of the security has been below its cost or amortized cost; • any downgrades of the security by a rating agency; • our intent not to sell the security for a sufficient time period for it to recover its value; • the likelihood of being forced to sell the security before the recovery of its value; and • an evaluation as to whether there are any credit losses on debt securities. We reviewed all securities with unrealized losses in accordance with the impairment policy described above. The Company determined that the unrealized losses in the fixed maturity securities portfolio related primarily to changes in market interest rates since the date of purchase, current conditions in the capital markets and the impact of those conditions on market liquidity and prices generally. We expect to recover the carrying value of these securities as it is not more likely than not that we will be required to sell the securities before the recovery of the amortized cost basis. During the three months ended March 31, 2018 and 2017, there were no impairment losses recognized for other-than-temporary declines in the fair value of our investments Net realized losses in the three months ended March 31, 2018 were immaterial. Net realized losses in the three months ended March 31, 2017 were $0.2 million resulting from called fixed maturity securities.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 5. Income Taxes In accordance with FASB ASC Topic 740, “Income Taxes,” we provide for the recognition and measurement of deferred income tax benefits based on the likelihood of their realization in future years. As of March 31, 2018, the Company had no material unrecognized tax benefits and no adjustments to liabilities or operations were required. In December 2017, the Tax Act was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017. As a result, we recorded a decrease to our net deferred tax assets revalued at the new lower rate of 21% in the fourth quarter of 2017, the period in which the legislation was enacted. The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. There were no uncertain tax positions recognized for the periods ended March 31, 2018 and 2017. Tax years 2014 through 2017 are subject to examination by the federal and state taxing authorities.

Loss Reserves

Loss Reserves	3 Months Ended
	Mar. 31, 2018
Insurance [Abstract]
Loss Reserves	Note 6. Loss Reserves We record reserves for estimated losses under insurance policies that we write and for loss adjustment expenses related to the investigation and settlement of policy claims. Our reserves for loss and loss adjustment expenses represent the estimated cost of all reported and unreported loss and loss adjustment expenses incurred and unpaid as of a given point in time. The reserves for loss and loss adjustment expenses are estimated using individual case-basis valuations, statistical analyses and estimates based upon experience for unreported claims and their associated loss and loss adjustment expenses. Such estimates may be more or less than the amounts ultimately paid when the claims are settled. The estimates are subject to the effects of trends in loss severity and frequency. Although considerable variability is inherent in these estimates, management believes that the reserves for loss and loss adjustment expenses are adequate. The estimates are continually reviewed and adjusted as necessary as experience develops or new information becomes known. Any adjustments are included in current operations. See Note 9 to our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2017 for additional information regarding the Company’s loss and loss adjustment expense development. The following table provides the Company’s liability for unpaid loss and loss adjustment expenses, net of related amounts recoverable from reinsurers, for the three months ended March 31, 2018 and 2017: Three Months Ended March 31, 2018 2017 (in thousands) Balance, beginning of period $ 771,845 $ 742,776 Less amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses 84,889 78,256 Net balance, beginning of period 686,956 664,520 Add incurred related to: Current accident year 62,426 62,729 Prior accident years (9,264 ) (6,513 ) Total incurred 53,162 56,216 Less paid related to: Current accident year 4,686 3,206 Prior accident years 47,354 45,498 Total paid 52,040 48,704 Net balance, end of period 688,078 672,032 Add amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses 89,220 77,464 Balance, end of period $ 777,298 $ 749,496 The foregoing reconciliation reflects favorable development of the net reserves at March 31, 2018 and March 31, 2017. The favorable development reduced loss and loss adjustment expenses incurred by $9.3 million and $6.5 million in 2018 and 2017, respectively. The revisions to the Company’s reserves reflect new information gained by claims adjusters in the normal course of adjusting claims and is reflected in the financial statements when the information becomes available. It is typical for more serious claims to take several years or longer to settle and the Company continually revises estimates as more information about claimants’ medical conditions and potential disability becomes known and the claims get closer to being settled. Multiple factors can cause loss development both unfavorable and favorable. The favorable loss development we experienced across accident years was largely due to favorable case reserve development from closed claims and claims where the worker had reached maximum medical improvement.

Comprehensive Income and Accumu

Comprehensive Income and Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Comprehensive Income and Accumulated Other Comprehensive Income	Note 7. Comprehensive Income and Accumulated Other Comprehensive Income Comprehensive income was $10.3 million for the three months ended March 31, 2018, compared to $14.5 million for the three months ended March 31, 2017. The difference between net income as reported and comprehensive income was due to changes in unrealized gains and losses, net of tax on available-for-sale debt securities. Comprehensive income includes net income plus unrealized gains (losses) on our available-for-sale debt securities, net of tax. In reporting comprehensive income on a net basis in the statements of comprehensive income, we used a 21 percent tax rate in 2018 and a 35 percent tax rate in 2017. The following table illustrates the changes in the balance of each component of accumulated other comprehensive income for each period presented in the interim financial statements. Three Months Ended March 31, 2018 2017 (in thousands) Beginning balance $ 3,612 $ (492 ) Other comprehensive income (loss) before reclassification (5,634 ) 978 Amounts reclassified from accumulated other comprehensive income (214 ) (26 ) Net current period other comprehensive income (loss) (5,848 ) 952 Ending balance $ (2,236 ) $ 460 The sale or other-than-temporary impairment of an available-for-sale security results in amounts being reclassified from accumulated other comprehensive income to current period net income. The effects of reclassifications out of accumulated other comprehensive income by the respective line items of net income are presented in the following table. Component of Accumulated Other Comprehensive Income Three Months Ended March 31, Affected line item in the statement of income 2018 2017 (in thousands) Unrealized gains on available-for- sale securities $ 17 $ 40 Net realized losses on investments 17 40 Income before income taxes (57 ) (14 ) Income tax expense $ (40 ) $ 26 Net income

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 8. 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. Fair value is defined in ASC Topic 820 as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is the price to sell an asset or transfer a liability and, therefore, represents an exit price, not an entry price. Fair value is the exit price in the principal market (or, if lacking a principal market, the most advantageous market) in which the reporting entity would transact. Fair value is a market-based measurement, not an entity-specific measurement, and, as such, is determined based on the assumptions that market participants would use in pricing the asset or liability. The exit price objective of a fair value measurement applies regardless of the reporting entity’s intent and/or ability to sell the asset or transfer the liability at the measurement date. ASC Topic 820 requires the use of valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities. The income approach uses valuation techniques to convert future amounts, such as cash flows or earnings, to a single present value amount on a discounted basis. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset, also known as current replacement cost. Valuation techniques used to measure fair value are to be consistently applied. In ASC Topic 820, inputs refer broadly to the assumptions that market participants would use in pricing the asset or liability, including assumptions about risk, for example, the risk inherent in a particular valuation technique used to measure fair value (such as a pricing model) and/or the risk inherent in the inputs to the valuation technique. Inputs may be observable or unobservable: • Observable inputs are inputs that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from sources independent of the reporting entity. • Unobservable inputs are inputs that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. Valuation techniques used to measure fair value are intended to maximize the use of observable inputs and minimize the use of unobservable inputs. ASC Topic 820 establishes a fair value hierarchy that prioritizes the use of inputs used in valuation techniques into the following three levels: • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability, or inputs that are derived principally from or corroborated by observable market data. • Level 3 inputs are unobservable inputs for the asset or liability. Unobservable inputs are to be used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally developed models that primarily use, as inputs, observable market-based parameters. The fair values of the Company’s investments are based upon prices provided by an independent pricing service. The Company has reviewed these prices for reasonableness and has not adjusted any prices received from the independent provider. Securities reported at fair value utilizing Level 1 inputs represent assets whose fair value is determined based upon observable unadjusted quoted market prices for identical assets in active markets. Level 2 securities represent assets whose fair value is determined using observable market information such as previous day trade prices, quotes from less active markets or quoted prices of securities with similar characteristics. There were no transfers between Level 1 and Level 2 during the three months ended March 31, 2018. At March 31, 2018, assets measured at fair value on a recurring basis are summarized below: March 31, 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 $ — $ 234,098 $ — $ 234,098 Corporate bonds — 142,774 — 142,774 U.S. agency-based mortgage-backed securities — 16,985 — 16,985 U.S. Treasury securities 65,407 — — 65,407 Total securities available-for-sale—fixed maturity 65,407 393,857 — 459,264 Securities available-for-sale—equity: Domestic common stock 11,391 — 34 11,425 Total available-for-sale $ 76,798 $ 393,857 $ 34 $ 470,689 At March 31, 2018, assets measured at amortized cost are summarized below: March 31, 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 $ — $ 452,346 $ — $ 452,346 Corporate bonds — 98,747 — 98,747 U.S. agency-based mortgage-backed securities — 9,831 — 9,831 U.S. Treasury securities 4,912 — — 4,912 Obligations of U.S. government agencies — 53,859 — 53,859 Asset-backed securities — 1,241 — 1,241 Total held-to-maturity $ 4,912 $ 616,024 $ — $ 620,936 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 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 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 The Company determines fair value amounts for financial instruments using available third-party market information. When such information is not available, the Company determines the fair value amounts using appropriate valuation methodologies. Nonfinancial instruments such as real estate, property and equipment, deferred policy acquisition costs, deferred income taxes and loss and loss adjustment expense reserves are excluded from the fair value disclosure. The following table presents summary information regarding changes in the fair value of assets measured at fair value using Level 3 input. Three Months Ended Twelve Months Ended March 31, 2018 December 31, 2017 (in thousands) Balance, beginning of period $ 34 $ — Transfer into Level 3 — 34 Balance, end of period $ 34 $ 34 At March 31, 2018, the Company held one security measured at fair value on a nonrecurring basis due to a recognized impairment of $0.1 million. The security is valued using Level 2 inputs and had a value of $12,000 at March 31, 2018. The security was valued at fair value at the time of impairment and is currently being carried at the adjusted amortized cost. The fair value of the security was $33,000 at March 31, 2018. Cash and Cash Equivalents —The carrying amounts reported in the accompanying consolidated balance sheets for these financial instruments approximate their fair values, which are characterized as Level 1 assets. Investments —The fair values for fixed maturity and equity securities are based on prices obtained from an independent pricing service. Equity and treasury securities are characterized as Level 1 assets, as their fair values are based on quoted prices in active markets. Fixed maturity securities, other than treasury securities, are characterized as Level 2 assets, as their fair values are determined using observable market inputs. Short Term Investments —The carrying amounts reported in the accompanying consolidated balance sheets for these financial instruments approximate their fair values. These securities are characterized as Level 2 assets in the fair value hierarchy. The following table summarizes the carrying values and corresponding fair values for financial instruments: As of March 31, 2018 As of December 31, 2017 Carrying Amount Fair Value Carrying Amount Fair Value (in thousands) Assets: Fixed maturity securities—held-to-maturity $ 619,400 $ 620,936 $ 629,668 $ 639,309 Fixed maturity securities—available-for-sale 459,264 459,264 465,594 465,594 Equity securities 11,425 11,425 9,282 9,282 Short-term investments 44,704 44,704 25,770 25,770 Cash and cash equivalents 36,072 36,072 55,559 55,559

Treasury Stock

Treasury Stock	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Treasury Stock	Note 9. Treasury Stock The Company’s Board of Directors initiated a share repurchase program in February 2010. In October 2016, the Board reauthorized this program with a limit of $25.0 million with no expiration date. There were no shares repurchased under this program in the three months ended March 31, 2018 and 2017.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Note 10. Subsequent Events On April 24, 2018, the Company’s Board of Directors declared a quarterly cash dividend of $0.22 per share payable on June 22, 2018 to shareholders of record as of June 8, 2018. The Board considers the payment of a regular cash dividend each calendar quarter.

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Adopted Accounting Guidance	Adopted Accounting Guidance In January 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. This guidance requires fair value measurement for equity investments (not including those that result in consolidation of the investee or use the equity method of accounting) and the recognition of changes in fair value to be presented as a component of net income. The guidance also revises the disclosure requirements related to fair value changes of liabilities presented in comprehensive income, eliminates disclosure related to the methods and assumptions underlying fair value for financial instruments measured at amortized cost, and simplifies impairment assessments for equity investments without readily determinable fair values. The adoption of this new guidance in the first quarter of 2018 resulted in an immaterial decrease in net income of $390 thousand or a $0.02 decrease in our diluted earnings per common share. In May 2014, the FASB issued ASU 2014-09 (Topic 606): Revenue from Contract s In February 2018, the FASB issued ASU 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220). This ASU provided new guidance on reclassification from Other Comprehensive Income (“OCI”) of tax effects related to recently passed tax reform legislation. The guidance gives entities the option to reclassify to retained earnings tax effects related to items in accumulated OCI deemed to be stranded as a result of tax reform. The guidance was effective for us in the first quarter of 2018 and was applied retrospectively. The Company’s policy for releasing income tax effects from accumulated OCI was the individual securities approach for available-for-sale securities. The adoption of this guidance did not have a material impact on our financial condition and results of operations. In December 2017, the SEC issued Staff Accounting Bulletin (SAB) 118 which provided guidance on accounting for tax effects of the Tax Act. Among many changes of the Tax Act which affected Property and Casualty Insurers, the Tax Act required property and casualty taxpayers to discount loss reserves based solely on IRS factors and no longer by reference to historical payment patterns. As the IRS has yet to release the 2018 discount factors, we have used the 2017 IRS discount factors to estimate the impact of the change in loss reserve discounting factors and have adjusted our deferred tax balances at March 31, 2018 for the impact of these changes. As prescribed by SAB 118, we continue to utilize the discount factors based on existing accounting guidance and the provisions of the tax laws that were in effect immediately prior to enactment of the Tax Act. Once the IRS has released the 2018 loss reserve discount factors, we will complete our analysis and include the effect of the difference in the reserve discount factors in the period the analysis is complete or the impact is reasonably estimable.
Prospective Accounting Guidance	Prospective Accounting Guidance In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). Under current guidance for lessees, leases are only included on the balance sheet if certain criteria, classifying the contract as a capital lease, are met. The new guidance requires a lessee to recognize a lease liability and a right of use asset for all leases extending beyond twelve months. The new guidance is effective for us in the first quarter of 2019. Upon adoption, leases will be recognized and measured at the beginning of the earliest period presented using a modified retrospective approach. Adoption of the guidance is not expected to have a material effect on the Company’s consolidated financial statements as the Company does not have any significant leases. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses. The new guidance replaces the methodology of credit loss impairment, which currently, delays the recognition of credit losses until a probable loss has been incurred. The new guidance requires credit losses for securities measured at amortized cost to be determined using current expected credit loss estimates. These estimates are to be derived from historical, current and reasonable supporting forecasts, including prepayments and estimates, and will be recorded through a valuation allowance account that will run through the income statement. The same method will be used for available-for-sale securities, but the valuation allowance will be limited to the amount by which the fair value is below amortized cost. The standard is effective for us in the first quarter of 2020. The Company will continue to monitor and evaluate the impact as the implementation date approaches. All other issued but not yet effective accounting and reporting standards as of March 31, 2018 are either not applicable to the Company or are not expected to have a material impact on the Company.

Fair Value Measurements (Polici

Fair Value Measurements (Policies)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
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.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Calculation of Basic and Diluted Earnings Per Share	The diluted EPS calculation includes potential common shares assumed issued under the treasury stock method, which reflects the potential dilution that would occur if any outstanding options were exercised or restricted stock becomes vested. Three Months Ended March 31, 2018 2017 (in thousands, except share and per share amounts) Basic EPS Net income - basic $ 16,169 $ 13,524 Basic weighted average common shares 19,187,136 19,150,400 Basic earnings per common share $ 0.84 $ 0.71 Diluted EPS Net income - diluted $ 16,169 $ 13,524 Diluted weighted average common shares: Weighted average common shares 19,187,136 19,150,400 Stock options and restricted stock 75,101 79,725 Diluted weighted average common shares 19,262,237 19,230,125 Diluted earnings per common share $ 0.84 $ 0.70

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2018
Gross Unrealized Gains and Losses and Amortized Cost and Fair Value of Investments Classified as Held-to-maturity	The gross unrealized gains and losses on, and the amortized cost and fair value of, those investments classified as held-to-maturity at March 31, 2018 are summarized as follows: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) States and political subdivisions $ 450,553 $ 5,041 $ (3,248 ) $ 452,346 Corporate bonds 99,368 29 (650 ) 98,747 U.S. agency-based mortgage-backed securities 9,400 503 (72 ) 9,831 U.S. Treasury securities and obligations of U.S. government agencies 58,857 456 (542 ) 58,771 Asset-backed securities 1,222 26 (7 ) 1,241 Totals $ 619,400 $ 6,055 $ (4,519 ) $ 620,936 The gross unrealized gains and losses on, and the amortized cost and fair value of, those investments classified as held-to-maturity at December 31, 2017 are summarized as follows: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) States and political subdivisions $ 460,428 $ 9,628 $ (955 ) $ 469,101 Corporate bonds 100,024 190 (167 ) 100,047 U.S. agency-based mortgage-backed securities 10,260 625 (40 ) 10,845 U.S. Treasury securities and obligations of U.S. government agencies 57,657 548 (198 ) 58,007 Asset-backed securities 1,299 25 (15 ) 1,309 Totals $ 629,668 $ 11,016 $ (1,375 ) $ 639,309
Gross Unrealized Gains and Losses and Cost or Amortized Cost and Fair Value of Investments Classified as Available-for-sale	The gross unrealized gains and losses on, and the cost or amortized cost and fair value of, those investments classified as available-for-sale at March 31, 2018 are summarized as follows: Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Fixed maturity: States and political subdivisions $ 232,778 $ 3,730 $ (2,410 ) $ 234,098 Corporate bonds 143,712 5 (943 ) 142,774 U.S. agency-based mortgage-backed securities 18,260 — (1,275 ) 16,985 U.S. Treasury securities and obligations of U.S. government agencies 67,283 — (1,876 ) 65,407 Total fixed maturity 462,033 3,735 (6,504 ) 459,264 Equity securities 11,425 — — 11,425 Totals $ 473,458 $ 3,735 $ (6,504 ) $ 470,689 The gross unrealized gains and losses on, and the cost or amortized cost and fair value of, those investments classified as available-for-sale at December 31, 2017 are summarized as follows: Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Fixed maturity: States and political subdivisions $ 244,898 $ 6,819 $ (577 ) $ 251,140 Corporate bonds 130,210 224 (212 ) 130,222 U.S. agency-based mortgage-backed securities 18,813 — (799 ) 18,014 U.S. Treasury securities and obligations of U.S. government agencies 67,315 29 (1,126 ) 66,218 Total fixed maturity 461,236 7,072 (2,714 ) 465,594 Equity securities 8,503 779 — 9,282 Totals $ 469,739 $ 7,851 $ (2,714 ) $ 474,876
Investment Securities Continuous Unrealized Loss Position	The following table summarizes the fair value and gross unrealized losses on securities, aggregated by major investment category and length of time that the individual securities have been in a continuous unrealized loss position: Less Than 12 Months 12 Months or Greater Total Fair Value of Investments with Unrealized Losses Gross Unrealized Losses Fair Value of Investments with Unrealized Losses Gross Unrealized Losses Fair Value of Investments with Unrealized Losses Gross Unrealized Losses (in thousands) March 31, 2018 Held-to-Maturity Fixed maturity securities: States and political subdivisions $ 212,693 $ 2,810 $ 14,513 $ 438 $ 227,206 $ 3,248 Corporate bonds 89,227 629 2,259 21 91,486 650 U.S. agency-based mortgage-backed securities 2,613 72 — — 2,613 72 U.S. Treasury securities and obligations of U.S. government agencies 48,489 439 4,468 103 52,957 542 Asset-backed securities 535 5 47 2 582 7 Total held-to-maturity securities 353,557 3,955 21,287 564 374,844 4,519 Available-for Sale Fixed maturity securities: States and political subdivisions $ 89,896 $ 1,620 $ 8,892 $ 790 $ 98,788 $ 2,410 Corporate bonds 138,600 943 — — 138,600 943 U.S. agency-based mortgage-backed securities 14,477 451 2,508 824 16,985 1,275 U.S. Treasury securities and obligations of U.S. government agencies 25,022 713 40,385 1,163 65,407 1,876 Total available-for-sale securities 267,995 3,727 51,785 2,777 319,780 6,504 Total $ 621,552 $ 7,682 $ 73,072 $ 3,341 $ 694,624 $ 11,023 Less Than 12 Months 12 Months or Greater Total Fair Value of Investments with Unrealized Losses Gross Unrealized Losses Fair Value of Investments with Unrealized Losses Gross Unrealized Losses Fair Value of Investments with Unrealized Losses Gross Unrealized Losses (in thousands) December 31, 2017 Held-to-Maturity Fixed maturity securities: States and political subdivisions $ 110,698 $ 654 $ 19,895 $ 301 $ 130,593 $ 955 Corporate bonds 56,425 156 4,121 11 60,546 167 U.S. agency-based mortgage-backed securities 2,798 40 — — 2,798 40 U.S. Treasury securities and obligations of U.S. government agencies 48,153 122 3,948 76 52,101 198 Asset-backed securities — — 967 15 967 15 Total held-to-maturity securities 218,074 972 28,931 403 247,005 1,375 Available-for Sale Fixed maturity securities: States and political subdivisions $ 23,365 $ 86 $ 19,153 $ 491 $ 42,518 $ 577 Corporate bonds 82,795 171 5,888 41 88,683 212 U.S. agency-based mortgage-backed securities 14,686 59 3,328 740 18,014 799 U.S. Treasury securities and obligations of U.S. government agencies 14,730 204 47,716 922 62,446 1,126 Total available-for-sale securities 135,576 520 76,085 2,194 211,661 2,714 Total $ 353,650 $ 1,492 $ 105,016 $ 2,597 $ 458,666 $ 4,089
Held-to-Maturity Securities [Member]
Summary of Amortized Cost and Fair Value of Investments in Fixed Maturity Securities, by Contractual Maturity	A summary of the amortized cost and fair value of investments in fixed maturity securities, classified as held-to-maturity at March 31, 2018, by contractual maturity, is as follows: Amortized Cost Fair Value (in thousands) Maturity: Within one year $ 97,545 $ 97,835 After one year through five years 255,343 255,678 After five years through ten years 94,872 95,139 After ten years 161,018 161,212 U.S. agency-based mortgage-backed securities 9,400 9,831 Asset-backed securities 1,222 1,241 Totals $ 619,400 $ 620,936
Available-for-Sale Securities [Member]
Summary of Amortized Cost and Fair Value of Investments in Fixed Maturity Securities, by Contractual Maturity	A summary of the amortized cost and fair value of investments in fixed maturity securities, classified as available-for-sale at March 31, 2018, by contractual maturity, is as follows: Amortized Cost Fair Value (in thousands) Maturity: Within one year $ 71,596 $ 71,476 After one year through five years 164,449 162,658 After five years through ten years 38,945 38,371 After ten years 168,783 169,774 U.S. agency-based mortgage-backed securities 18,260 16,985 Totals $ 462,033 $ 459,264

Loss Reserves (Tables)

Loss Reserves (Tables)	3 Months Ended
	Mar. 31, 2018
Insurance [Abstract]
Liability for Unpaid Loss and Loss Adjustment Expenses, Net of Related Amounts Recoverable from Reinsurers	The following table provides the Company’s liability for unpaid loss and loss adjustment expenses, net of related amounts recoverable from reinsurers, for the three months ended March 31, 2018 and 2017: Three Months Ended March 31, 2018 2017 (in thousands) Balance, beginning of period $ 771,845 $ 742,776 Less amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses 84,889 78,256 Net balance, beginning of period 686,956 664,520 Add incurred related to: Current accident year 62,426 62,729 Prior accident years (9,264 ) (6,513 ) Total incurred 53,162 56,216 Less paid related to: Current accident year 4,686 3,206 Prior accident years 47,354 45,498 Total paid 52,040 48,704 Net balance, end of period 688,078 672,032 Add amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses 89,220 77,464 Balance, end of period $ 777,298 $ 749,496

Comprehensive Income and Accu23

Comprehensive Income and Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Income (AOCI)	The following table illustrates the changes in the balance of each component of accumulated other comprehensive income for each period presented in the interim financial statements. Three Months Ended March 31, 2018 2017 (in thousands) Beginning balance $ 3,612 $ (492 ) Other comprehensive income (loss) before reclassification (5,634 ) 978 Amounts reclassified from accumulated other comprehensive income (214 ) (26 ) Net current period other comprehensive income (loss) (5,848 ) 952 Ending balance $ (2,236 ) $ 460
Reclassification Out of Accumulated Other Comprehensive Income	The effects of reclassifications out of accumulated other comprehensive income by the respective line items of net income are presented in the following table. Component of Accumulated Other Comprehensive Income Three Months Ended March 31, Affected line item in the statement of income 2018 2017 (in thousands) Unrealized gains on available-for- sale securities $ 17 $ 40 Net realized losses on investments 17 40 Income before income taxes (57 ) (14 ) Income tax expense $ (40 ) $ 26 Net income

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Assets Measured at Fair Value on Recurring Basis	At March 31, 2018, assets measured at fair value on a recurring basis are summarized below: March 31, 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 $ — $ 234,098 $ — $ 234,098 Corporate bonds — 142,774 — 142,774 U.S. agency-based mortgage-backed securities — 16,985 — 16,985 U.S. Treasury securities 65,407 — — 65,407 Total securities available-for-sale—fixed maturity 65,407 393,857 — 459,264 Securities available-for-sale—equity: Domestic common stock 11,391 — 34 11,425 Total available-for-sale $ 76,798 $ 393,857 $ 34 $ 470,689 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 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 March 31, 2018, assets measured at amortized cost are summarized below: March 31, 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 $ — $ 452,346 $ — $ 452,346 Corporate bonds — 98,747 — 98,747 U.S. agency-based mortgage-backed securities — 9,831 — 9,831 U.S. Treasury securities 4,912 — — 4,912 Obligations of U.S. government agencies — 53,859 — 53,859 Asset-backed securities — 1,241 — 1,241 Total held-to-maturity $ 4,912 $ 616,024 $ — $ 620,936 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. Three Months Ended Twelve Months Ended March 31, 2018 December 31, 2017 (in thousands) Balance, beginning of period $ 34 $ — Transfer into Level 3 — 34 Balance, end of period $ 34 $ 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 March 31, 2018 As of December 31, 2017 Carrying Amount Fair Value Carrying Amount Fair Value (in thousands) Assets: Fixed maturity securities—held-to-maturity $ 619,400 $ 620,936 $ 629,668 $ 639,309 Fixed maturity securities—available-for-sale 459,264 459,264 465,594 465,594 Equity securities 11,425 11,425 9,282 9,282 Short-term investments 44,704 44,704 25,770 25,770 Cash and cash equivalents 36,072 36,072 55,559 55,559

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Percentage of comparable consolidated amounts	95.00%	95.00%
ASU 2016-01 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Decrease in net income	$ 390
ASU 2016-01 [Member] | Common Shares [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Decrease in diluted earnings per common share	$ 0.02

Stock Options and Restricted 26

Stock Options and Restricted Stock - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)Incentive_Planshares	Mar. 31, 2017USD ($)shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of equity incentive plans | Incentive_Plan	3
Stock options exercised, Shares | shares	15,000	0
Proceeds from stock option exercises	$ 68,000
Share-based compensation expense	$ 18,000	$ 400,000

Earnings Per Share - Calculatio

Earnings Per Share - Calculation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share Basic [Abstract]
Net income - basic	$ 16,169	$ 13,524
Basic weighted average common shares	19,187,136	19,150,400
Basic earnings per common share	$ 0.84	$ 0.71
Net income - diluted	$ 16,169	$ 13,524
Weighted average common shares	19,187,136	19,150,400
Stock options and restricted stock	75,101	79,725
Diluted weighted average common shares	19,262,237	19,230,125
Diluted earnings per common share	$ 0.84	$ 0.70

Investments - Gross Unrealized

Investments - Gross Unrealized Gains and Losses and Amortized Cost and Fair Value of Investments Classified as Held-to-Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment [Line Items]
Held-to-maturity, Amortized Cost, Totals	$ 619,400	$ 629,668
Held-to-Maturity, Gross Unrealized Gains	6,055	11,016
Held-to-Maturity, Gross Unrealized Losses	(4,519)	(1,375)
Held-to-Maturity, Fair Value	620,936	639,309
States and Political Subdivisions [Member]
Investment [Line Items]
Held-to-maturity, Amortized Cost, Totals	450,553	460,428
Held-to-Maturity, Gross Unrealized Gains	5,041	9,628
Held-to-Maturity, Gross Unrealized Losses	(3,248)	(955)
Held-to-Maturity, Fair Value	452,346	469,101
Corporate Bonds [Member]
Investment [Line Items]
Held-to-maturity, Amortized Cost, Totals	99,368	100,024
Held-to-Maturity, Gross Unrealized Gains	29	190
Held-to-Maturity, Gross Unrealized Losses	(650)	(167)
Held-to-Maturity, Fair Value	98,747	100,047
U.S. Agency-Based Mortgage-Backed Securities [Member]
Investment [Line Items]
Held-to-maturity, Amortized Cost, Totals	9,400	10,260
Held-to-Maturity, Gross Unrealized Gains	503	625
Held-to-Maturity, Gross Unrealized Losses	(72)	(40)
Held-to-Maturity, Fair Value	9,831	10,845
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Investment [Line Items]
Held-to-maturity, Amortized Cost, Totals	58,857	57,657
Held-to-Maturity, Gross Unrealized Gains	456	548
Held-to-Maturity, Gross Unrealized Losses	(542)	(198)
Held-to-Maturity, Fair Value	58,771	58,007
Asset-Backed Securities [Member]
Investment [Line Items]
Held-to-maturity, Amortized Cost, Totals	1,222	1,299
Held-to-Maturity, Gross Unrealized Gains	26	25
Held-to-Maturity, Gross Unrealized Losses	(7)	(15)
Held-to-Maturity, Fair Value	$ 1,241	$ 1,309

Investments - Gross Unrealize29

Investments - Gross Unrealized Gains and Losses and Cost or Amortized Cost and Fair Value of Investments Classified as Available-for-Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment [Line Items]
Available-for-Sale, Cost or Amortized Cost	$ 473,458	$ 469,739
Available-for-Sale, Gross Unrealized Gains	3,735	7,851
Available-for-Sale, Gross Unrealized Losses	(6,504)	(2,714)
Available-for-Sale, Fair Value	470,689	474,876
Total Fixed Maturity [Member]
Investment [Line Items]
Available-for-Sale, Cost or Amortized Cost	462,033	461,236
Available-for-Sale, Gross Unrealized Gains	3,735	7,072
Available-for-Sale, Gross Unrealized Losses	(6,504)	(2,714)
Available-for-Sale, Fair Value	459,264	465,594
States and Political Subdivisions [Member]
Investment [Line Items]
Available-for-Sale, Cost or Amortized Cost	232,778	244,898
Available-for-Sale, Gross Unrealized Gains	3,730	6,819
Available-for-Sale, Gross Unrealized Losses	(2,410)	(577)
Available-for-Sale, Fair Value	234,098	251,140
Corporate Bonds [Member]
Investment [Line Items]
Available-for-Sale, Cost or Amortized Cost	143,712	130,210
Available-for-Sale, Gross Unrealized Gains	5	224
Available-for-Sale, Gross Unrealized Losses	(943)	(212)
Available-for-Sale, Fair Value	142,774	130,222
U.S. Agency-Based Mortgage-Backed Securities [Member]
Investment [Line Items]
Available-for-Sale, Cost or Amortized Cost	18,260	18,813
Available-for-Sale, Gross Unrealized Losses	(1,275)	(799)
Available-for-Sale, Fair Value	16,985	18,014
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Investment [Line Items]
Available-for-Sale, Cost or Amortized Cost	67,283	67,315
Available-for-Sale, Gross Unrealized Gains		29
Available-for-Sale, Gross Unrealized Losses	(1,876)	(1,126)
Available-for-Sale, Fair Value	65,407	66,218
Equity Securities [Member]
Investment [Line Items]
Available-for-Sale, Cost or Amortized Cost	11,425	8,503
Available-for-Sale, Gross Unrealized Gains		779
Available-for-Sale, Fair Value	$ 11,425	$ 9,282

Investments - Summary of Amorti

Investments - Summary of Amortized Cost and Fair Value of Investments in Fixed Maturity Securities, Classified as Held-to-Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment [Line Items]
Within one year, Amortized Cost	$ 97,545
After one year through five years, Amortized Cost	255,343
After five years through ten years, Amortized Cost	94,872
After ten years, Amortized Cost	161,018
Held-to-maturity, Amortized Cost, Totals	619,400	$ 629,668
Within one year, Fair Value	97,835
After one year through five years, Fair Value	255,678
After five years through ten years, Fair Value	95,139
After ten years, Fair Value	161,212
Held-to-maturity, Fair Value, Totals	620,936	$ 639,309
U.S. Agency-Based Mortgage-Backed Securities [Member]
Investment [Line Items]
Held-to-maturity, Amortized Cost	9,400
Held-to-maturity, Fair Value	9,831
Asset-Backed Securities [Member]
Investment [Line Items]
Held-to-maturity, Amortized Cost	1,222
Held-to-maturity, Fair Value	$ 1,241

Investments - Summary of Amor31

Investments - Summary of Amortized Cost and Fair Value of Investments in Fixed Maturity Securities, Classified as Available-for-Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment [Line Items]
Within one year, Amortized Cost	$ 71,596
After one year through five years, Amortized Cost	164,449
After five years through ten years, Amortized Cost	38,945
After ten years, Amortized Cost	168,783
Total, Amortized Cost	462,033	$ 461,236
Within one year, Fair Value	71,476
After one year through five years, Fair Value	162,658
After five years through ten years, Fair Value	38,371
After ten years, Fair Value	169,774
Total, Fair Value	459,264	$ 465,594
U.S. Agency-Based Mortgage-Backed Securities [Member]
Investment [Line Items]
Available-for-sale securities, Amortized Cost	18,260
Available-for-sale securities, Fair value	$ 16,985

Investments - Investment Securi

Investments - Investment Securities Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment [Line Items]
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	$ 353,557	$ 218,074
Held-to-maturity securities, Gross Unrealized Losses, Less Than 12 Months	3,955	972
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	21,287	28,931
Held-to-maturity securities, Gross Unrealized Losses, 12 Months or Greater	564	403
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Total	374,844	247,005
Held-to-maturity securities, Gross Unrealized Losses, Total	4,519	1,375
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	267,995	135,576
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	3,727	520
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	51,785	76,085
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	2,777	2,194
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	319,780	211,661
Available-for Sale, Gross Unrealized Losses, Total	6,504	2,714
Fair Value of Investments with Unrealized Losses, Less Than 12 months	621,552	353,650
Gross Unrealized Loss, Less Than 12 Months	7,682	1,492
Fair Value of Investments with Unrealized Losses, 12 Months or Greater	73,072	105,016
Gross Unrealized Losses, 12 Months or Greater	3,341	2,597
Fair Value of Investments with Unrealized Losses, Total	694,624	458,666
Gross Unrealized Losses, Total	11,023	4,089
States and Political Subdivisions [Member]
Investment [Line Items]
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	212,693	110,698
Held-to-maturity securities, Gross Unrealized Losses, Less Than 12 Months	2,810	654
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	14,513	19,895
Held-to-maturity securities, Gross Unrealized Losses, 12 Months or Greater	438	301
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Total	227,206	130,593
Held-to-maturity securities, Gross Unrealized Losses, Total	3,248	955
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	89,896	23,365
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	1,620	86
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	8,892	19,153
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	790	491
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	98,788	42,518
Available-for Sale, Gross Unrealized Losses, Total	2,410	577
Corporate Bonds [Member]
Investment [Line Items]
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	89,227	56,425
Held-to-maturity securities, Gross Unrealized Losses, Less Than 12 Months	629	156
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	2,259	4,121
Held-to-maturity securities, Gross Unrealized Losses, 12 Months or Greater	21	11
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Total	91,486	60,546
Held-to-maturity securities, Gross Unrealized Losses, Total	650	167
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	138,600	82,795
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	943	171
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater		5,888
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater		41
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	138,600	88,683
Available-for Sale, Gross Unrealized Losses, Total	943	212
U.S. Agency-Based Mortgage-Backed Securities [Member]
Investment [Line Items]
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	2,613	2,798
Held-to-maturity securities, Gross Unrealized Losses, Less Than 12 Months	72	40
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Total	2,613	2,798
Held-to-maturity securities, Gross Unrealized Losses, Total	72	40
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	14,477	14,686
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	451	59
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	2,508	3,328
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	824	740
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	16,985	18,014
Available-for Sale, Gross Unrealized Losses, Total	1,275	799
Asset-Backed Securities [Member]
Investment [Line Items]
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	535
Held-to-maturity securities, Gross Unrealized Losses, Less Than 12 Months	5
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	47	967
Held-to-maturity securities, Gross Unrealized Losses, 12 Months or Greater	2	15
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Total	582	967
Held-to-maturity securities, Gross Unrealized Losses, Total	7	15
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Investment [Line Items]
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	48,489	48,153
Held-to-maturity securities, Gross Unrealized Losses, Less Than 12 Months	439	122
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	4,468	3,948
Held-to-maturity securities, Gross Unrealized Losses, 12 Months or Greater	103	76
Held-to-maturity securities, Fair Value of Investments with Unrealized Losses, Total	52,957	52,101
Held-to-maturity securities, Gross Unrealized Losses, Total	542	198
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	25,022	14,730
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	713	204
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	40,385	47,716
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	1,163	922
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	65,407	62,446
Available-for Sale, Gross Unrealized Losses, Total	$ 1,876	$ 1,126

Investments - Additional Inform

Investments - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)Security	Mar. 31, 2017USD ($)
Investments Schedule [Abstract]
Individual fixed maturity held in unrealized loss position | Security	448
Individual fixed maturity held in unrealized loss position longer than 12 months | Security	44
Impairment losses recognized | $	$ 0	$ 0
Net realized losses on investments | $	$ (31,000)	$ (181,000)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended			12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 0
U.S. federal income tax statutory rate	21.00%	21.00%		35.00%
Company recognized uncertain tax positions	$ 0		$ 0

Loss Reserves - Liability for U

Loss Reserves - Liability for Unpaid Loss and Loss Adjustment Expenses, Net of Related Amounts Recoverable from Reinsurers (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Roll Forward In Liability For Unpaid Claims And Claims Adjustment Expense [Abstract]
Balance, beginning of period	$ 771,845	$ 742,776
Less amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses	84,889	78,256
Net balance, beginning of period	686,956	664,520
Add incurred related to:
Current accident year	62,426	62,729
Prior accident years	(9,264)	(6,513)
Total incurred	53,162	56,216
Less paid related to:
Current accident year	4,686	3,206
Prior accident years	47,354	45,498
Total paid	52,040	48,704
Net balance, end of period	688,078	672,032
Add amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses	89,220	77,464
Balance, end of period	$ 777,298	$ 749,496

Loss Reserves - Additional Info

Loss Reserves - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Insurance [Abstract]
Loss and LAE Related to Prior Periods	$ 9,264	$ 6,513

Comprehensive Income and Accu37

Comprehensive Income and Accumulated Other Comprehensive Income - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Comprehensive income	$ 10,321	$ 14,476
Comprehensive income tax rate	21.00%	35.00%

Comprehensive Income and Accu38

Comprehensive Income and Accumulated Other Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Income (AOCI) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 425,423
Ending Balance	432,068
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	3,612	$ (492)
Other comprehensive income (loss) before reclassification	(5,634)	978
Amounts reclassified from accumulated other comprehensive income	(214)	(26)
Net current period other comprehensive income (loss)	(5,848)	952
Ending Balance	$ (2,236)	$ 460

Comprehensive Income and Accu39

Comprehensive Income and Accumulated Other Comprehensive Income - Reclassification Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 19,414	$ 18,733
Income tax expense	(3,245)	(5,209)
Net income	16,169	13,524
Unrealized Gains on Available-for-Sale Securities [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains on available-for- sale securities	17	40
Income before income taxes	17	40
Income tax expense	(57)	(14)
Net income	$ (40)	$ 26

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	$ 470,689	$ 474,876
Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	11,425	9,282
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	470,689	474,876
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	459,264	465,594
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	76,798	75,466
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	65,407	66,218
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	393,857	399,376
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	393,857	399,376
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	34	34
Fair Value, Measurements, Recurring [Member] | Common Stock [Member] | Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	11,425	9,282
Fair Value, Measurements, Recurring [Member] | Common Stock [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	11,391	9,248
Fair Value, Measurements, Recurring [Member] | Common Stock [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	34	34
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	234,098	251,140
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	234,098	251,140
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	142,774	130,222
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	142,774	130,222
Fair Value, Measurements, Recurring [Member] | U.S. Agency-Based Mortgage-Backed Securities [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	16,985	18,014
Fair Value, Measurements, Recurring [Member] | U.S. Agency-Based Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	16,985	18,014
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	65,407	66,218
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-Sale, Fair Value	$ 65,407	$ 66,218

Fair Value Measurements - Sch41

Fair Value Measurements - Schedule of Assets Measured at Amortized Cost (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	$ 620,936	$ 639,309
States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	452,346	469,101
Corporate Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	98,747	100,047
U.S. Agency-Based Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	9,831	10,845
U.S. Treasury Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	4,912	6,750
Obligations of U.S. Government Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	53,859	51,257
Asset-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	1,241	1,309
Fair Value, Inputs, Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	4,912	6,750
Fair Value, Inputs, Level 1 [Member] | U.S. Treasury Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	4,912	6,750
Fair Value, Inputs, Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	616,024	632,559
Fair Value, Inputs, Level 2 [Member] | States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	452,346	469,101
Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	98,747	100,047
Fair Value, Inputs, Level 2 [Member] | U.S. Agency-Based Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	9,831	10,845
Fair Value, Inputs, Level 2 [Member] | Obligations of U.S. Government Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	53,859	51,257
Fair Value, Inputs, Level 2 [Member] | Asset-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held-to-maturity-fixed maturity, Fair Value	$ 1,241	$ 1,309

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Information Regarding Changes in Fair Value of Assets Measured at Fair Value (Detail) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 34
Transfer into Level 3		$ 34
Balance, end of period	$ 34	$ 34

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities held to maturity, carrying value	$ 619,400,000	$ 629,668,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Recognized impairment	100,000
Securities held to maturity, carrying value	12,000
Securities held to maturity, fair value	$ 33,000

Fair Value Measurements - Sum44

Fair Value Measurements - Summary of Carrying Values and Corresponding Fair Values for Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-held-to-maturity	$ 619,400	$ 629,668
Fixed maturity securities-held-to-maturity	620,936	639,309
Fixed maturity securities-available-for-sale	459,264	465,594
Equity securities	11,425	9,282
Short-term investments	44,704	25,770
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-held-to-maturity	620,936	639,309
Fixed maturity securities-available-for-sale	459,264	465,594
Equity securities	11,425	9,282
Short-term investments	44,704	25,770
Cash and cash equivalents	36,072	55,559
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-available-for-sale	459,264	465,594
Equity securities	11,425	9,282
Short-term investments	44,704	25,770
Cash and cash equivalents	$ 36,072	$ 55,559

Treasury Stock - Additional Inf

Treasury Stock - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Oct. 31, 2016
Equity [Abstract]
Share repurchase program, new limit amount			$ 25,000,000
Shares repurchased under the program	0	0

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - Subsequent Event [Member] - Dividend Declared [Member]	Apr. 24, 2018$ / shares
Subsequent Event [Line Items]
Cash dividend per share	$ 0.22
Date of payment to shareholders entitled to dividends	Jun. 22, 2018
Date of record of shareholders entitled to dividends	Jun. 8, 2018