RLI (RLI) 10-K 21 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 07, 2020	Jun. 30, 2019
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2019
Entity File Number	001-09463
Entity Registrant Name	RLI CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	37-0889946
Entity Address, Address Line One	9025 North Lindbergh Drive
Entity Address, City or Town	Peoria
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	61615
City Area Code	309
Local Phone Number	692-1000
Title of 12(b) Security	Common Stock $0.01 par value
Trading Symbol	RLI
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 3,450,441,098
Entity Common Stock, Shares Outstanding		44,919,277
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0000084246
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investments:
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	$ 1,983,086	$ 1,760,515
Equity securities, at fair value (cost - $262,131 in 2019 and $220,373 in 2018)	460,630	340,483
Short-term investments, at cost which approximates fair value		11,550
Other invested assets	70,441	51,542
Cash	46,203	30,140
Total investments and cash	2,560,360	2,194,230
Accrued investment income	14,587	14,033
Premiums and reinsurance balances receivable, net of allowances for uncollectible amounts of $16,682 in 2019 and $16,967 in 2018	160,369	152,576
Ceded unearned premium	93,656	71,174
Reinsurance balances recoverable on unpaid losses and settlement expenses, net of allowances for uncollectible amounts of $9,402 in 2019 and $9,793 in 2018	384,517	364,999
Deferred policy acquisition costs	85,044	84,934
Property and equipment, at cost, net of accumulated depreciation of $62,703 in 2019 and $54,275 in 2018	53,121	54,692
Investment in unconsolidated investees	103,836	94,967
Goodwill and intangibles	54,127	54,534
Other assets	36,104	18,926
TOTAL ASSETS	3,545,721	3,105,065
Liabilities:
Unpaid losses and settlement expenses	1,574,352	1,461,348
Unearned premiums	540,213	496,505
Reinsurance balances payable	25,691	22,591
Funds held	83,358	72,309
Income taxes - deferred	56,727	24,238
Bonds payable, long-term debt	149,302	149,115
Accrued expenses	66,626	45,124
Other liabilities	54,064	26,993
TOTAL LIABILITIES	2,550,333	2,298,223
Shareholders' Equity
Common stock ($0.01 par value, 100,000,000 shares authorized; 67,799,229 shares issued, 44,869,015 shares outstanding in 2019; 67,434,257 shares issued, 44,504,043 shares outstanding in 2018)	678	674
Paid-in capital	321,190	305,660
Accumulated other comprehensive earnings (loss)	52,473	(14,572)
Retained earnings	1,014,046	908,079
Deferred compensation	7,980	8,354
Less: Treasury shares at cost (22,930,214 shares in 2019 and 2018)	(400,979)	(401,353)
TOTAL SHAREHOLDERS' EQUITY	995,388	806,842
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 3,545,721	$ 3,105,065

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Condensed Consolidated Balance Sheets
Available-for-sale, amortized cost	$ 1,915,278	$ 1,776,465
Equity securities, cost	262,131	220,373
Premiums and reinsurance balances receivable, allowances for uncollectible amounts	16,682	16,967
Reinsurance balances recoverable on unpaid losses and settlement expenses, allowances for uncollectible amounts	9,402	9,793
Property and equipment, accumulated depreciation	$ 62,703	$ 54,275
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	67,799,229	67,434,257
Common stock, shares outstanding (in shares)	44,869,015	44,504,043
Treasury stock, shares (in shares)	22,930,214	22,930,214

Condensed Consolidated Statemen

Condensed Consolidated Statements of Earnings and Comprehensive Earnings - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Consolidated Statements of Earnings and Comprehensive Earnings
Net premiums earned	$ 839,111,000	$ 791,366,000	$ 737,937,000
Net investment income	68,870,000	62,085,000	54,876,000
Net realized gains	17,520,000	63,624,000	6,970,000
Other-than-temporary-impairment (OTTI) losses on investments	0	(217,000)	(2,559,000)
Net unrealized gains (losses) on equity securities	78,090,000	(98,735,000)
Consolidated revenue	1,003,591,000	818,123,000	797,224,000
Losses and settlement expenses	413,416,000	428,193,000	401,584,000
Policy acquisition costs	288,697,000	267,738,000	252,515,000
Insurance operating expenses	69,430,000	53,803,000	56,994,000
Interest expense on debt	7,588,000	7,437,000	7,426,000
General corporate expenses	12,686,000	9,427,000	11,340,000
Total expenses	791,817,000	766,598,000	729,859,000
Equity in earnings of unconsolidated investees	20,960,000	16,056,000	17,224,000
Earnings before income taxes	232,734,000	67,581,000	84,589,000
Income tax expense:
Current	26,426,000	23,917,000	9,302,000
Deferred income tax expense (benefit)	14,666,000	(20,515,000)	(29,741,000)
Income tax expense	41,092,000	3,402,000	(20,439,000)
Net earnings	191,642,000	64,179,000	105,028,000
Other comprehensive earnings (loss), net of tax	67,045,000	(33,997,000)	35,309,000
Comprehensive earnings	$ 258,687,000	$ 30,182,000	$ 140,337,000
Basic:
Net earnings per share (in dollars per share)	$ 4.28	$ 1.45	$ 2.39
Comprehensive earnings per share (in dollars per share)	5.78	0.68	3.19
Diluted:
Net earnings per share (in dollars per share)	4.23	1.43	2.36
Comprehensive earnings per share (in dollars per share)	$ 5.72	$ 0.67	$ 3.15
Weighted average number of common shares outstanding
Basic (in shares)	44,734	44,358	44,033
Diluted (in shares)	45,257	44,835	44,500
Cash dividends paid per common share	$ 1.91	$ 1.87	$ 2.58

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Common stock	Paid-in Capital	Accumulated Other Comprehensive Earnings (Loss)	Retained Earnings	Deferred Compensation	Treasury Stock at Cost	Total
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2016	$ 66,875	$ 229,779	$ 122,610	$ 797,307	$ 11,496	$ (404,495)	$ 823,572
Balance (in shares) at Dec. 31, 2016	43,944,697
Increase (Decrease) in Shareholders' Equity
Net earnings				105,028			105,028
Other comprehensive earnings (loss), net of tax			35,309				35,309
Deferred compensation					(2,856)	2,856
Share-based compensation	$ 204	3,298					3,502
Share-based compensation (in shares)	203,658
Dividends and dividend equivalents				(113,813)			(113,813)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2017	$ 67,079	233,077	157,919	788,522	8,640	(401,639)	853,598
Balance (in shares) at Dec. 31, 2017	44,148,355
Increase (Decrease) in Shareholders' Equity
Par value conversion from $1.00 per share to $0.01 per share	$ (66,409)	66,409
Net earnings				64,179			64,179
Other comprehensive earnings (loss), net of tax			(33,997)				(33,997)
Deferred compensation					(286)	286
Share-based compensation	$ 4	6,174					6,178
Share-based compensation (in shares)	355,688
Dividends and dividend equivalents				(83,202)			(83,202)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2018	$ 674	305,660	(14,572)	908,079	8,354	(401,353)	806,842
Balance (in shares) at Dec. 31, 2018	44,504,043
Increase (Decrease) in Shareholders' Equity
Cumulative-effect adjustment from ASU 2016-01 and 2018-02			(138,494)	138,580			86
Net earnings				191,642			191,642
Other comprehensive earnings (loss), net of tax			67,045				67,045
Deferred compensation					(374)	374
Share-based compensation	$ 4	15,530					15,534
Share-based compensation (in shares)	364,972
Dividends and dividend equivalents				(85,675)			(85,675)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2019	$ 678	$ 321,190	$ 52,473	$ 1,014,046	$ 7,980	$ (400,979)	$ 995,388
Balance (in shares) at Dec. 31, 2019	44,869,015

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Consolidated Statements of Shareholders' Equity
Cash dividends paid per common share	$ 1.91	$ 1.87	$ 2.58
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 1

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Earnings (loss) before equity in net earnings of subsidiaries	$ 191,642,000	$ 64,179,000	$ 105,028,000
Adjustments to reconcile net earnings to net cash provided by operating activities
Net realized gains	(17,520,000)	(63,407,000)	(4,411,000)
Net unrealized (gains) losses on equity securities	(78,090,000)	98,735,000
Depreciation	8,164,000	7,042,000	6,944,000
Deferred income tax expense (benefit)	14,666,000	(20,515,000)	(29,741,000)
Other items, net	25,341,000	6,171,000	16,368,000
Change in:
Accrued investment income	(552,000)	1,132,000	(573,000)
Premiums and reinsurance balances receivable (net of direct write-offs and commutations)	(7,793,000)	(18,225,000)	(7,964,000)
Reinsurance balances payable	3,100,000	967,000	3,696,000
Funds held	11,049,000	(2,251,000)	1,818,000
Ceded unearned premium	(22,482,000)	(13,246,000)	(5,755,000)
Reinsurance balances recoverable on unpaid losses	(19,518,000)	(63,008,000)	(13,767,000)
Deferred policy acquisition costs	(110,000)	(7,218,000)	(4,569,000)
Accrued expenses	21,502,000	(7,724,000)	856,000
Unpaid losses and settlement expenses	113,004,000	189,845,000	132,166,000
Unearned premiums	43,708,000	45,056,000	17,672,000
Current income taxes payable	(1,434,000)	5,725,000	(3,019,000)
Changes in investment in unconsolidated investees:
Undistributed earnings	(20,960,000)	(16,056,000)	(17,224,000)
Dividends received	13,200,000	9,900,000	0
Net Cash Provided by (Used in) Operating Activities, Total	276,917,000	217,102,000	197,525,000
Purchase of:
Fixed income, available-for-sale	(539,726,000)	(725,675,000)	(430,727,000)
Equity securities	(89,486,000)	(115,921,000)	(20,719,000)
Property and equipment	(6,955,000)	(6,087,000)	(9,238,000)
Other	(22,751,000)	(18,754,000)	(19,112,000)
Proceeds from sale of:
Fixed income, available-for-sale	196,558,000	395,019,000	168,760,000
Proceeds from sale of equity securities	62,172,000	147,838,000	36,573,000
Property and equipment		167,000	128,000
Subsidiary or agency			408,000
Other	2,502,000	3,394,000	2,063,000
Proceeds from call or maturity of:
Fixed income, available-for-sale	201,383,000	187,380,000	195,617,000
Payments for (Proceeds from) Short-term Investments
Net proceeds from sale (purchase) of short-term investments	11,550,000	(1,570,000)	(4,965,000)
Net cash used in investing activities	(184,753,000)	(134,209,000)	(81,212,000)
Cash Flows from Financing Activities
Proceeds from stock option exercises	9,490,000	6,076,000	3,502,000
Cash dividends paid	(85,591,000)	(83,100,000)	(113,813,000)
Net cash used in financing activities	(76,101,000)	(77,024,000)	(110,311,000)
Net increase (decrease) in cash	16,063,000	5,869,000	6,002,000
Cash at the beginning of the period	30,140,000	24,271,000	18,269,000
Cash at the end of the period	$ 46,203,000	$ 30,140,000	$ 24,271,000

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	1.   SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES ​ A. DESCRIPTION OF BUSINESS ​ RLI Corp. is an insurance holding company. References to “the Company,” “we,” “our,” “us” or like terms refer to the business of RLI Corp. and its subsidiaries. We underwrite select property and casualty insurance coverages through major subsidiaries collectively known as RLI Insurance Group. We conduct operations principally through three insurance companies. RLI Insurance Company (RLI Ins.), a subsidiary of RLI Corp. and our principal insurance subsidiary, writes multiple lines of insurance on an admitted basis in all 50 states, the District of Columbia, Puerto Rico, the Virgin Islands and Guam. Mt. Hawley Insurance Company (Mt. Hawley), a subsidiary of RLI Ins., writes excess and surplus lines insurance on a non-admitted basis in all 50 states, the District of Columbia, Puerto Rico, the Virgin Islands and Guam. Contractors Bonding and Insurance Company (CBIC), a subsidiary of RLI Ins., writes multiple lines of insurance on an admitted basis in all 50 states and the District of Columbia. ​ On May 4, 2018, RLI Corp. changed its state of incorporation from the State of Illinois to the State of Delaware (the Reincorporation). The Reincorporation was effected by merging RLI Corp., an Illinois corporation (RLI Illinois), into RLI Corp., a Delaware corporation (RLI Delaware). The separate corporate existence of RLI Illinois ceased and RLI Delaware continues in existence as the surviving corporation and possesses all rights, privileges, powers and franchises of RLI Illinois. The Reincorporation did not result in any change in the name, business, management, fiscal year, location of the principal executive offices, assets or liabilities of the Company. Each outstanding share of RLI Illinois common stock, which had a par value of $1.00 per share, was automatically converted into one outstanding share of RLI Delaware common stock, with a par value of $0.01 per share. In order to reflect the new par value of common stock on the balance sheet, a $66.4 million reclassification from common stock to paid -in-capital was made. ​ B. PRINCIPLES OF CONSOLIDATION AND BASIS OF PRESENTATION ​ The accompanying consolidated financial statements were prepared in conformity with generally accepted accounting principles in the United States of America (GAAP), which differ in some respects from those followed in reports to insurance regulatory authorities. The consolidated financial statements include the accounts of our holding company and our subsidiaries. Intercompany balances and transactions have been eliminated. Certain reclassifications were made to 2018 and 2017 to conform to the classifications used in the current year. The Company has evaluated subsequent events through the date these consolidated financial statements were issued. There were no subsequent events requiring adjustment to the financial statements or disclosure. ​ C. ADOPTED ACCOUNTING STANDARDS ​ ASU 2016-02, Leases (Topic 842) ​ ASU 2016-02 was issued to improve the financial reporting of leasing transactions. Under previous guidance for lessees, leases were only included on the balance sheet if certain criteria, classifying the agreement as a capital lease, were met. This update requires the recognition of a right-of-use asset and a corresponding lease liability, discounted to the present value, for all leases that extend beyond 12 months. For operating leases, the asset and liability are expensed over the lease term on a straight-line basis, with all cash flows included in the operating section of the statement of cash flows. For finance leases, interest on the lease liability is recognized separately from the amortization of the right-of-use asset in the statement of earnings and the repayment of the principal portion of the lease liability is classified as a financing activity while the interest component is included in the operating section of the statement of cash flows. ​ We adopted ASU 2016-02, ASU 2018-10 Codification Improvements to Topic 842: Leases and ASU 2018-11 Leases (Topic 842): Targeted Improvements on January 1, 2019. We applied the standards using the alternative transition method provided by ASU 2018-11 under which leases were recognized at the date of adoption and a cumulative-effect adjustment to the opening balance of retained earnings would have been recognized in the period of adoption. As the standard did not have an impact on our net earnings, no adjustment to the opening balance of retained earnings was required. As of December 31, 2019, $22.3 million of right-of-use assets and $24.5 million of lease liabilities were included in the other assets and other liabilities line items of the consolidated balance sheet, respectively, as a result of the adoption of these updates. We implemented controls for the adoption of the standard and the ongoing monitoring of the right-of-use asset and lease liability, but they did not materially affect our internal control over financial reporting. ASU 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities ​ Under previous guidance, the amortization period for callable debt securities held at a premium was generally the contractual life of the instrument. However, if an entity had a large number of similar loans, it could consider estimates of future principal prepayments. For those who chose not to incorporate an estimate of future prepayments, ASU 2017-08 shortens the amortization period for premium on debt securities to the earliest call date, rather than the maturity date, to align the amortization method with how the securities are quoted, priced and traded. After the earliest call date, if the call option is not exercised, the entity shall reset the effective yield using the payment terms of the debt security. Any excess of the amortized cost basis over the amount payable will be amortized to the next call date or to maturity if there are no other call dates. The method of accounting for a discount does not change and will continue to be amortized over the life of the bond. ​ We adopted ASU 2017-08 on January 1, 2019 using a modified-retrospective approach. As we had been incorporating estimates of future principal prepayments when calculating the effective yield for bonds carrying a premium under the old guidance, the adoption of this update did not have a material impact on our financial statements. ​ ASU 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ​ ASU 2018-07 was issued to simplify the accounting for share-based transactions by expanding the scope of Topic 718 from only being applicable to share-based payments to employees to include share-based payment transactions for acquiring goods and services from nonemployees. As a result, nonemployee share-based transactions will be measured by estimating the fair value of the equity instruments at the grant date, taking into consideration the probability of satisfying performance conditions. We adopted ASU 2018-07 on January 1, 2019. Our long-term incentive plan limits the awards of share-based payments to employees and directors of the Company. As our share-based compensation expense to nonemployee directors was $0.6 million in 2019, the standard did not have a material impact on our financial statements. ​ D. PROSPECTIVE ACCOUNTING STANDARDS ​ ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) ​ ASU 2016-13 was issued to provide more decision-useful information about the expected credit losses on financial instruments. Current GAAP delays the recognition of credit losses until it is probable a loss has been incurred. The update will require a financial asset measured at amortized cost, including reinsurance balances recoverable, to be presented at the net amount expected to be collected by means of an allowance for credit losses that runs through net earnings. Credit losses relating to available-for-sale debt securities will also be recorded through an allowance for credit losses. However, the amendments would limit the amount of the allowance to the amount by which fair value is below amortized cost. The measurement of credit losses on available-for-sale securities is similar under current GAAP, but the update requires the use of the allowance account through which amounts can be reversed, rather than through an irreversible write-down. ​ This ASU is effective for annual and interim reporting periods beginning after December 15, 2019. Early adoption is permitted beginning after December 15, 2018. Upon adoption, the update will be applied using the modified-retrospective approach, by which a cumulative-effect adjustment will be made to retained earnings as of the beginning of the first reporting period in which the guidance is effective. This update will have the most impact on our available-for-sale fixed income portfolio and reinsurance balances recoverable. However, as our fixed income portfolio is weighted towards higher rated bonds (85 percent rated A or better at December 31, 2019) and we purchase reinsurance from financially strong reinsurers for which we already have an allowance for uncollectible reinsurance amounts, the effect of adoption will not have a material impact on our financial statements. ​ ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement ​ ASU 2018-13 modifies the disclosure requirements for assets and liabilities measured at fair value. The requirements to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, the policy for timing of transfers between levels and the valuation processes for Level 3 fair value measurements have all been removed. However, the changes in unrealized gains and losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period must be disclosed along with the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements (or other quantitative information if it is more reasonable). Finally, for investments measured at net asset value, the requirements have been modified so that the timing of liquidation and the date when restrictions from redemption might lapse are only disclosed if the investee has communicated the timing to the entity or announced the timing publicly. ​ This ASU is effective for annual and interim reporting periods beginning after December 15, 2019. As the amendments are only disclosure related, the effect of adoption will not have a material impact on our financial statements. ​ E. INVESTMENTS ​ Equity securities are carried at fair value with unrealized gains and losses recorded within net earnings in 2019 and 2018. Prior to 2018, unrealized gains and losses on equity securities were recognized through other comprehensive earnings. Investments in fixed income securities are classified into one of three categories: trading, held-to-maturity or available-for-sale. All of our fixed income securities are classified as available-for-sale and reported at fair value. Unrealized gains and losses on these securities are excluded from net earnings but are recorded as a separate component of comprehensive earnings and shareholders’ equity, net of deferred income taxes. ​ Other-than-Temporary Impairment ​ We regularly evaluate our fixed income securities using quantitative and qualitative criteria to determine impairment losses for other-than-temporary declines in the fair value of the investments. The following are the key factors for determining if a security is other-than-temporarily impaired: ​ ● The length of time and the extent to which the fair value has been less than amortized cost, ​ ● The probability of significant adverse changes to the cash flows, ​ ● The occurrence of a discrete credit event resulting in the issuer defaulting on a material obligation, the issuer seeking protection from creditors under the bankruptcy laws, the issuer proposing a voluntary reorganization under which creditors are asked to exchange their claims for cash or securities having a fair value substantially lower than par value of their claims or ​ ● The probability that we will recover the entire amortized cost basis of our fixed income securities prior to maturity. ​ Quantitative criteria considered during this process include, but are not limited to: the degree and duration of current fair value as compared to the amortized cost of the security, degree and duration of the security’s fair value being below cost and whether the issuer is in compliance with terms and covenants of the security. Qualitative criteria include the credit quality, current economic conditions, the anticipated speed of cost recovery, the financial health of and specific prospects for the issuer, as well as our absence of intent to sell or requirement to sell fixed income securities prior to recovery. In addition, we consider price declines in our other-than-temporary impairment (OTTI) analysis when they provide evidence of declining credit quality, and we distinguish between price changes caused by credit deterioration, as opposed to rising interest rates. See note 2 for further discussion of OTTI. ​ Interest on fixed maturities and short-term investments is credited to earnings on an accrual basis. Premiums and discounts are amortized or accreted over the lives of the related fixed maturities. Dividends on equity securities are credited to earnings on the ex-dividend date. Realized gains and losses on disposition of investments are based on specific identification of the investments sold on the settlement date. ​ F. CASH, SHORT-TERM INVESTMENTS AND OTHER INVESTED ASSETS ​ Cash consists of uninvested balances in bank accounts. Short-term investments consist of investments with original maturities of 90 days or less, primarily AAA-rated prime and government money market funds. Short-term investments are carried at cost. We have not experienced losses on these instruments. Other invested assets include investments in low income housing tax credit partnerships (LIHTC), membership in the Federal Home Loan Bank of Chicago (FHLBC) and investments in private funds. Our LIHTC investments are carried at amortized cost, and our investment in FHLBC stock is carried at cost. Due to the nature of cash, short-term investments, the LIHTC and our membership in the FHLBC, their carrying amounts approximate fair value. The private funds are carried at fair value, using each investment’s net asset value. ​ G. REINSURANCE ​ Ceded unearned premiums and reinsurance balances recoverable on paid and unpaid losses and settlement expenses are reported separately as assets, instead of being netted with the related liabilities, since reinsurance does not relieve the Company of our legal liability to our policyholders. ​ We continuously monitor the financial condition of our reinsurers. As part of our monitoring efforts, we review their annual financial statements, quarterly disclosures and Securities and Exchange Commission (SEC) filings for reinsurers that are publicly traded. We also review insurance industry developments that may impact the financial condition of our reinsurers. We analyze the credit risk associated with our reinsurance balances recoverable by monitoring the AM Best and Standard & Poor’s (S&P) ratings of our reinsurers. In addition, we subject our reinsurance recoverables to detailed recoverable tests, including one based on average default by S&P rating. Based upon our review and testing, our policy is to charge to earnings, in the form of an allowance, an estimate of unrecoverable amounts from reinsurers. This allowance is reviewed on an ongoing basis to ensure that the amount makes a reasonable provision for reinsurance balances that we may be unable to recover. ​ H. POLICY ACQUISITION COSTS ​ We defer incremental direct costs that relate to the successful acquisition of new or renewal insurance contracts, including commissions and premium taxes. Acquisition-related costs may be deemed ineligible for deferral when they are based on contingent or performance criteria beyond the basic acquisition of the insurance contract or when efforts to obtain or renew the insurance contract are unsuccessful. All eligible costs are capitalized and charged to expense in proportion to premium revenue recognized. The method followed in computing deferred policy acquisition costs limits the amount of such deferred costs to their estimated realizable value. This process contemplates the premiums to be earned, anticipated losses and settlement expenses and certain other costs expected to be incurred, but does not consider investment income. Judgments as to the ultimate recoverability of such deferred costs are reviewed on a segment basis and are highly dependent upon estimated future loss costs associated with the premiums written. This deferral methodology applies to both gross and ceded premiums and acquisition costs. ​ I. PROPERTY AND EQUIPMENT ​ Property and equipment are presented at cost less accumulated depreciation and are depreciated on a straight-line basis for financial statement purposes over periods ranging from 3 to 10 years for equipment and up to 30 years for buildings and improvements. ​ J. INVESTMENTS IN UNCONSOLIDATED INVESTEES ​ We maintain a 40 percent interest in the equity and earnings of Maui Jim, Inc. (Maui Jim), a manufacturer of high-quality sunglasses, which is accounted for under the equity method. We also maintain a similar minority representation on their board of directors. Maui Jim’s chief executive officer owns a controlling majority of the outstanding shares of Maui Jim. We carry this investment at the holding company level as it is not core to our insurance operations. Our investment in Maui Jim was $79.6 million at December 31, 2019 and $79.5 million at December 31, 2018. In 2019, we recorded $13.6 million in investee earnings for Maui Jim, compared to $12.5 million in 2018 and $14.4 million in 2017. Maui Jim recorded net income of $35.6 million in 2019, $30.3 million in 2018 and $34.4 million in 2017. Additional summarized financial information for Maui Jim for 2019 and 2018 is outlined in the following table: ​ ​ ​ ​ ​ ​ ​ ​ ​ (in millions) 2019 2018 Total assets ​ $ 282.2 ​ $ 265.6 ​ Total liabilities ​ 104.8 ​ 90.4 ​ Total equity ​ 177.4 ​ 175.2 ​ ​ Approximately $69.3 million of undistributed earnings from Maui Jim are included in our retained earnings as of December 31, 2019. We received dividends of $13.2 million and $9.9 million from Maui Jim in 2019 and 2018, respectively. No dividends were received in 2017. ​ As of December 31, 2019, we had a 23 percent interest in the equity and earnings of Prime Holdings Insurance Services, Inc. (Prime), which is accounted for under the equity method. Prime writes business through two Illinois domiciled insurance carriers, Prime Insurance Company, an excess and surplus lines company, and Prime Property and Casualty Insurance Inc., an admitted insurance company. Our investment in Prime was $24.2 million at December 31, 2019 and $15.4 million at December 31, 2018. In 2019, we recorded $7.4 million in investee earnings for Prime, compared to $3.6 million in 2018 and $2.8 million in 2017. Additionally, we maintain a quota share reinsurance treaty with Prime, which contributed $13.1 million of gross premiums written and $28.7 million of net premiums earned during 2019, compared to $41.1 million of gross premiums written and $34.2 million of net premiums earned during 2018 and $29.6 million of gross premiums written and $21.0 million of net premiums earned during 2017. The decrease in gross written premium is reflective of our decreased quota share participation with Prime. ​ We perform annual impairment reviews of our investments in unconsolidated investees, which take into consideration current valuation and operating results. Based upon the most recent reviews, the assets were not impaired. ​ K. INTANGIBLE ASSETS ​ Goodwill and intangibles totaled $54.1 million and $54.5 million at December 31, 2019 and 2018, respectively, as detailed in the following table: ​ ​ ​ ​ ​ ​ ​ ​ Goodwill and Intangible Assets ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ 2019 ​ ​ 2018 Goodwill ​ ​ ​ ​ ​ ​ Energy surety ​ $ 25,706 ​ $ 25,706 Miscellaneous and contract surety ​ ​ 15,110 ​ ​ 15,110 Small commercial ​ ​ 5,246 ​ ​ 5,246 Total goodwill ​ $ 46,062 ​ $ 46,062 ​ ​ ​ ​ ​ ​ ​ Intangibles ​ ​ ​ ​ ​ ​ State insurance licenses ​ $ 7,500 ​ $ 7,500 Definite-lived intangibles, net of accumulated amortization of $3,470 ​ ​ 565 ​ ​ 972 Total intangibles ​ $ 8,065 ​ $ 8,472 ​ ​ ​ ​ ​ ​ ​ Total goodwill and intangibles ​ $ 54,127 ​ $ 54,534 ​ As the amortization of goodwill and indefinite-lived intangible assets is not permitted, the assets are tested for impairment on an annual basis, or earlier if there is reason to suspect that their values may have been diminished or impaired. Annual impairment testing was performed on each of our goodwill and indefinite-lived intangible assets during 2019. Based upon these reviews, our energy surety goodwill, miscellaneous and contract surety goodwill, small commercial goodwill and state insurance license indefinite-lived intangible asset were not impaired. In addition, as of December 31, 2019, there were no triggering events on the above-mentioned goodwill and intangible assets that would suggest an updated review was necessary. ​ During the first quarter of 2018 and the second quarter of 2017, adverse loss experience triggered the need to test the medical professional liability reporting unit. The testing resulted in a $4.4 million non-cash impairment charge on goodwill and intangible assets in 2018 and a $3.4 million non-cash impairment charge on goodwill and intangible assets in 2017. In each instance, the fair value for the medical professional liability reporting unit’s agency relationships, carried as a definite-lived intangible asset, was determined by using a discounted cash flow valuation. In 2018, the carrying value exceeded the fair value, resulting in a $0.8 million non-cash impairment charge. In 2017, the resulting non-cash impairment charge on definite-lived intangibles was $1.8 million. The fair value for the medical professional liability reporting unit’s goodwill was determined by using a weighted average of a market approach and discounted cash flow valuation. The carrying value exceeded the fair value in each year, resulting in a $3.6 million non-cash impairment charge in 2018 and a $1.6 million non-cash impairment charge during 2017. Subsequent to the 2018 impairment, the medical professional liability reporting unit had no remaining goodwill or intangible assets. All impairment charges were recorded as net realized losses in the respective period’s consolidated statement of earnings. ​ The definite-lived intangible assets are amortized against future operating results based on their estimated useful lives. Amortization of intangible assets was $0.4 million, $0.4 million and $0.7 million for 2019, 2018 and 2017, respectively. We anticipate we will recognize amortization expense of $0.4 million in 2020, $0.1 million in 2021 and less than $0.1 million in 2022. ​ L. UNPAID LOSSES AND SETTLEMENT EXPENSES ​ The liability for unpaid losses and settlement expenses represents estimates of amounts needed to pay reported and unreported claims and related expenses. The estimates are based on certain actuarial and other assumptions related to the ultimate cost to settle such claims. Such assumptions are subject to occasional changes due to evolving economic, social and political conditions. All estimates are periodically reviewed and, as experience develops and new information becomes known, the reserves are adjusted as necessary. Such adjustments are reflected in the results of operations in the period in which they are determined. Due to the inherent uncertainty in estimating reserves for losses and settlement expenses, there can be no assurance that the ultimate liability will not exceed recorded amounts. If actual liabilities do exceed recorded amounts, there will be an adverse effect. Furthermore, we may determine that recorded reserves are more than adequate to cover expected losses, which would lead to a reduction in our reserves. ​ M. INSURANCE REVENUE RECOGNITION ​ Insurance premiums are recognized ratably over the term of the contracts, net of ceded reinsurance. Unearned premiums are calculated on a monthly pro rata basis. ​ N. INCOME TAXES ​ We file a consolidated federal income tax return. Federal income taxes are accounted for using the asset and liability method under which deferred income taxes are recognized for the tax consequences of temporary differences by applying enacted statutory tax rates applicable to future years to differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities, operating losses and tax credit carry forwards. The effect on deferred taxes for a change in tax rates is recognized in income in the period that includes the enactment date. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some of the deferred tax assets will not be realized. ​ We consider uncertainties in income taxes and recognize those in our financial statements as required. As it relates to uncertainties in income taxes, our unrecognized tax benefits, including interest and penalty accruals, are not considered material to the consolidated financial statements. Also, no tax uncertainties are expected to result in significant increases or decreases to unrecognized tax benefits within the next 12-month period. Penalties and interest related to income tax uncertainties, should they occur, would be included in income tax expense in the period in which they are incurred. ​ As an insurance company, we are subject to minimal state income tax liabilities. On a state basis, since the majority of our income is from insurance operations, we pay premium taxes which are calculated as a percentage of gross premiums written in lieu of state income taxes. Premium taxes are a component of policy acquisition costs. ​ O. EARNINGS PER SHARE ​ Basic earnings per share (EPS) is computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted EPS reflects the dilution that could occur if securities or other contracts to issue common stock or common stock equivalents were exercised or converted into common stock. When inclusion of these items increases the earnings per share or reduces the loss per share, the effect on earnings is anti-dilutive. Under these circumstances, the diluted net earnings or net loss per share is computed excluding these items. The following represents a reconciliation of the numerator and denominator of the basic and diluted EPS computations contained in the consolidated financial statements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average ​ ​ ​ ​ Income ​ Shares ​ Per Share (in thousands, except per share data) ​ (Numerator) ​ (Denominator) ​ Amount For the year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 191,642 44,734 ​ $ 4.28 ​ Stock options ​ — 523 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 191,642 45,257 ​ $ 4.23 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 64,179 44,358 ​ $ 1.45 ​ Stock options ​ — 477 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 64,179 44,835 ​ $ 1.43 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 105,028 44,033 ​ $ 2.39 ​ Stock options ​ — 467 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 105,028 44,500 ​ $ 2.36 ​ ​ P. COMPREHENSIVE EARNINGS ​ Financial Instruments – Overall (subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, ​ The table below illustrates the changes in the balance of each component of accumulated other comprehensive earnings for each period presented in the consolidated financial statements. The 2017 activity and balances include the net unrealized gain and loss activity on both fixed income and equity securities, while the 2019 and 2018 activity and ending balance reflect only the net unrealized gain and loss activity on fixed income securities due to the aforementioned adoption of ASU 2016-01. The changes in accumulated other comprehensive earnings also reflect adjustments from the adoption of two accounting standards. ASU 2016-01 necessitated a cumulative-effect adjustment in the beginning of 2018, which moved $142.2 million of net unrealized gains and losses on equity securities from accumulated other comprehensive earnings to retained earnings. ​ ASU 2018-02 addressed issues arising from the enactment of the Tax Cuts and Jobs Act of 2017. Deferred tax items are required to be revalued based on new tax laws with changes included in earnings. Since other comprehensive earnings was not affected by the revaluation of deferred tax items, the accumulated other comprehensive earnings balance was reflective of the historic tax rate instead of the newly enacted rate, which created a stranded tax effect. ASU 2018-02 allowed for the reclassification of our $3.7 million stranded tax effect out of accumulated other comprehensive earnings into retained earnings. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains/Losses on Available-for-Sale Securities ​ For the Year Ended December 31, (in thousands) 2019 2018 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning balance ​ $ (14,572) $ 157,919 $ 122,610 ​ Cumulative effect adjustment of ASU 2016-01 ​ ​ — ​ ​ (142,219) ​ ​ — ​ Adjusted beginning balance ​ $ (14,572) ​ $ 15,700 ​ $ 122,610 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive earnings before reclassifications ​ 69,560 (35,763) 40,887 ​ Amounts reclassified from accumulated other comprehensive earnings ​ (2,515) 1,766 (5,578) ​ Net current-period other comprehensive earnings (loss) ​ $ 67,045 $ (33,997) $ 35,309 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification of stranded tax effect from implementation of Tax Cuts and Jobs Act of 2017 ​ ​ — ​ ​ 3,725 ​ ​ — ​ Ending balance ​ $ 52,473 $ (14,572) $ 157,919 ​ ​ The sale or other-than-temporary impairment of an available-for-sale security results in amounts being reclassified from accumulated other comprehensive earnings to current period net earnings. The effects of reclassifications out of accumulated other comprehensive earnings by the respective line items of net earnings are presented in the following table. As previously mentioned, 2019 and 2018 reflect activity on available-for-sale fixed income securities, while 2017 also includes activity from the equity portfolio. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount Reclassified from Accumulated Other Comprehensive Earnings (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Component of Accumulated ​ For the Year Ended December 31, ​ Affected line item in the Other Comprehensive Earnings 2019 2018 2017 Consolidated Statement of Earnings ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized gains and losses on available-for-sale securities ​ $ 3,184 $ (2,018) $ 11,141 Net ​ ​ ​ — (217) (2,559) Other-than-temporary impairment losses on investments ​ ​ ​ $ 3,184 $ (2,235) $ 8,582 Earnings before income taxes ​ ​ ​ (669) 469 (3,004) Income tax expense ​ ​ ​ $ 2,515 $ (1,766) $ 5,578 Net earnings ​ ​ Q. FAIR VALUE DISCLOSURES ​ Fair value is defined as the price in the principal market that would be received for an asset to facilitate an orderly transaction between market participants on the measurement date. We determined the fair value of certain financial instruments based on their underlying characteristics and relevant transactions in the marketplace. We maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. ​ The following are the levels of the fair value hierarchy and a brief description of the type of valuation inputs that are used to establish each level. Financial assets are classified based upon the lowest level of significant input that is used to determine fair value. ​ ● Pricing Lev

INVESTMENTS

INVESTMENTS	12 Months Ended
	Dec. 31, 2019
INVESTMENTS
INVESTMENTS	2. INVESTMENTS ​ A summary of net investment income is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NET INVESTMENT INCOME ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Interest on fixed income securities $ 60,364 $ 54,491 $ 48,343 ​ Dividends on equity securities ​ 9,950 ​ 9,814 ​ 10,506 ​ Interest on cash, short-term investments and other invested assets ​ 3,674 ​ 2,309 ​ 945 ​ Gross investment income ​ $ 73,988 ​ $ 66,614 ​ $ 59,794 ​ Less investment expenses ​ (5,118) ​ (4,529) ​ (4,918) ​ Net investment income $ 68,870 ​ $ 62,085 ​ $ 54,876 ​ ​ Pretax net realized gains (losses) and net changes in unrealized gains (losses) on investments for the years ended December 31 are summarized below. As discussed in note 1.P., unrealized gains and losses on equity securities were recognized in net earnings in 2019 and 2018, after the adoption of ASU 2016-01, and were recognized in other comprehensive earnings in 2017. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ REALIZED/UNREALIZED GAINS (LOSSES) ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Net realized gains (losses): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed income: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 3,184 ​ $ (2,018) ​ $ 859 ​ Equity securities ​ 14,445 ​ 69,868 ​ 10,282 ​ Other ​ (109) ​ (4,226) ​ (4,171) ​ Total net realized gains (losses) ​ $ 17,520 ​ $ 63,624 ​ $ 6,970 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other-than-temporary-impairment losses on investments ​ $ — ​ $ (217) ​ $ (2,559) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net changes in unrealized gains (losses) on investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities ​ $ 78,389 ​ $ (98,380) ​ $ — ​ Other invested assets ​ ​ (299) ​ ​ (355) ​ ​ — ​ Total unrealized gains (losses) on equity securities recognized in net earnings ​ $ 78,090 ​ $ (98,735) ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed income: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 83,758 ​ $ (41,778) ​ $ 16,846 ​ Equity securities ​ ​ — ​ ​ — ​ ​ 36,844 ​ Other invested assets ​ ​ — ​ ​ — ​ ​ 29 ​ Investment in unconsolidated investees ​ ​ 1,109 ​ ​ (1,257) ​ ​ 604 ​ Total unrealized gains (losses) recognized in other comprehensive earnings ​ $ 84,867 ​ $ (43,035) ​ $ 54,323 ​ Net realized gains (losses) and changes in unrealized gains (losses) on investments ​ $ 180,477 ​ $ (78,363) ​ $ 58,734 ​ ​ During 2019, we recorded $17.5 million in net realized gains and $163.0 million of net unrealized gains. The majority of our net realized gains were due to sales of equity securities. The change in unrealized gain (loss) position was due to declining interest rates, increasing the fair value of fixed income securities, as well as strong equity market returns during 2019. For 2019, the net realized gains (losses) and changes in unrealized gains (losses) on investments totaled $180.5 million. ​ The following is a summary of the disposition of fixed income securities and equities for the years ended December 31, with separate presentations for sales and calls/maturities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net SALES ​ ​ ​ Gross Realized ​ Realized (in thousands) Proceeds Gains Losses Gain (Loss) ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 196,799 ​ $ 4,368 ​ $ (2,167) ​ $ 2,201 ​ Equities ​ 62,172 ​ 16,938 ​ (2,493) ​ 14,445 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 394,318 ​ $ 3,131 ​ $ (5,349) ​ $ (2,218) ​ Equities ​ 147,838 ​ 71,065 ​ (1,197) ​ 69,868 ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 169,002 ​ $ 2,406 ​ $ (1,670) ​ $ 736 ​ Equities ​ 36,573 ​ 13,178 ​ (2,896) ​ 10,282 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net CALLS/MATURITIES ​ ​ ​ ​ Gross Realized ​ Realized (in thousands) Proceeds Gains Losses Gain (Loss) 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 201,698 ​ $ 1,004 ​ $ (21) ​ $ 983 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 187,380 ​ $ 311 ​ $ (111) ​ $ 200 ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 195,617 ​ $ 262 ​ $ (139) ​ $ 123 ​ ​ FAIR VALUE MEASUREMENTS ​ Assets measured at fair value on a recurring basis as of December 31, 2019, are summarized below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted in Active ​ Significant Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ ​ ​ (in thousands) ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Total Fixed income securities - available-for-sale ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ — ​ $ 193,661 ​ $ — ​ $ 193,661 ​ U.S. agency ​ ​ — ​ ​ 38,855 ​ ​ — ​ ​ 38,855 ​ Non-U.S. government & agency ​ — ​ 7,628 ​ — ​ 7,628 ​ Agency MBS ​ — ​ 420,165 ​ — ​ 420,165 ​ ABS/CMBS/MBS* ​ — ​ 224,870 ​ — ​ 224,870 ​ Corporate ​ — ​ 690,297 ​ 1,770 ​ 692,067 ​ Municipal ​ — ​ 405,840 ​ — ​ 405,840 ​ Total fixed income securities - available-for-sale ​ $ — ​ $ 1,981,316 ​ $ 1,770 ​ $ 1,983,086 ​ Equity securities ​ 460,630 ​ — ​ — ​ 460,630 ​ Total ​ $ 460,630 ​ $ 1,981,316 ​ $ 1,770 ​ $ 2,443,716 ​ *Non-agency asset-backed, commercial mortgage-backed and mortgage-backed ​ Assets measured at fair value on a recurring basis as of December 31, 2018, are summarized below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted in Active ​ Significant Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ ​ ​ (in thousands) ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Total Fixed income securities - available-for-sale ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ — ​ $ 200,229 ​ $ — ​ $ 200,229 ​ U.S. agency ​ ​ — ​ ​ 31,904 ​ ​ — ​ ​ 31,904 ​ Non-U.S. government & agency ​ — ​ 7,639 ​ — ​ 7,639 ​ Agency MBS ​ — ​ 395,253 ​ — ​ 395,253 ​ ABS/CMBS/MBS* ​ — ​ 136,723 ​ — ​ 136,723 ​ Corporate ​ — ​ 668,679 ​ — ​ 668,679 ​ Municipal ​ — ​ 320,088 ​ — ​ 320,088 ​ Total fixed income securities - available-for-sale ​ $ — ​ $ 1,760,515 ​ $ — ​ $ 1,760,515 ​ Equity securities ​ 339,985 ​ 498 ​ — ​ 340,483 ​ Total ​ $ 339,985 ​ $ 1,761,013 ​ $ — ​ $ 2,100,998 ​ *Non-agency asset-backed, commercial mortgage-backed and mortgage-backed ​ As of December 31, 2019, we had $1.8 million of fixed income securities whose fair value was measured using significant unobservable inputs (Level 3). We did not own any Level 3 securities during 2018. Additionally, there were no securities transferred in or out of Levels 1, 2 or 3 during 2019 or 2018. ​ The amortized cost and estimated fair value of fixed income securities at December 31, 2019, by contractual maturity, are shown as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Amortized Cost Fair Value Available-for-sale ​ ​ ​ ​ ​ ​ ​ Due in one year or less ​ $ 49,951 ​ $ 50,170 ​ Due after one year through five years ​ 395,056 ​ 407,007 ​ Due after five years through 10 years ​ 580,310 ​ 613,099 ​ Due after 10 years ​ 255,321 ​ 267,775 ​ Mtge/ABS/CMBS* ​ 634,640 ​ 645,035 ​ Total available-for-sale ​ $ 1,915,278 ​ $ 1,983,086 ​ * ​ Expected maturities may differ from contractual maturities due to call provisions on some existing securities. At December 31, 2019, the net unrealized gains of available-for-sale fixed income securities totaled $67.8 million pretax. At December 31, 2018, the net unrealized losses of available-for-sale fixed maturities securities totaled $16.0 million pretax. ​ The following table is a schedule of amortized costs and estimated fair values of investments in fixed income securities as of December 31, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 ​ Amortized ​ ​ ​ ​ Gross Unrealized (in thousands) Cost Fair Value Gains Losses Available-for-sale ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ 186,699 ​ $ 193,661 ​ $ 6,994 ​ $ (32) ​ U.S. agency ​ 36,535 ​ 38,855 ​ 2,362 ​ (42) ​ Non-U.S. government & agency ​ 7,333 ​ 7,628 ​ 295 ​ — ​ Agency MBS ​ 411,808 ​ 420,165 ​ 8,920 ​ (563) ​ ABS/CMBS/MBS* ​ ​ 222,832 ​ ​ 224,870 ​ ​ 2,514 ​ ​ (476) ​ Corporate ​ 659,640 ​ 692,067 ​ 33,245 ​ (818) ​ Municipal ​ 390,431 ​ 405,840 ​ 16,131 ​ (722) ​ Total fixed income ​ $ 1,915,278 ​ $ 1,983,086 ​ $ 70,461 ​ $ (2,653) ​ * ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2018 ​ Amortized ​ ​ ​ ​ Gross Unrealized (in thousands) Cost Fair Value Gains Losses Available-for-sale ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ 199,982 ​ $ 200,229 ​ $ 1,232 ​ $ (985) ​ U.S. agency ​ 31,716 ​ 31,904 ​ 403 ​ (215) ​ Non-U.S. government & agency ​ 8,170 ​ 7,639 ​ — ​ (531) ​ Agency MBS ​ 402,992 ​ 395,253 ​ 1,709 ​ (9,448) ​ ABS/CMBS/MBS* ​ ​ 137,224 ​ ​ 136,723 ​ ​ 375 ​ ​ (876) ​ Corporate ​ 681,909 ​ 668,679 ​ 2,894 ​ (16,124) ​ Municipal ​ 314,472 ​ 320,088 ​ 6,926 ​ (1,310) ​ Total fixed income ​ $ 1,776,465 ​ $ 1,760,515 ​ $ 13,539 ​ $ (29,489) ​ * ​ Asset-Backed, Commercial Mortgage-Backed and Mortgage-Backed Securities ​ Gross unrealized losses in the collateralized securities bond portfolio decreased to $1.0 million in 2019 as interest rates declined during the year. Ninety-seven percent of our collateralized securities carry the highest credit rating by one or more major rating agencies and continue to pay according to contractual terms. ​ For all fixed income securities at an unrealized loss at December 31, 2019, we believe it is probable that we will receive all contractual payments in the form of principal and interest. In addition, we are not required to, nor do we intend to, sell these investments prior to recovering the entire amortized cost basis of each security, which may be at maturity. We do not consider these investments to be other-than-temporarily impaired at December 31, 2019. ​ Corporate Bonds ​ Gross unrealized losses in the corporate bond portfolio fell to $0.8 million in 2019 from $16.1 million at the end of 2018 as interest rates and credit spreads declined during the year. The corporate bond portfolio has an overall rating of BBB+. ​ Municipal Bonds ​ As of December 31, 2019, municipal bonds totaled $405.8 million with gross unrealized losses of $0.7 million, down from $1.3 million the previous year. As of December 31, 2019, approximately 42 percent of the municipal fixed income securities in the investment portfolio were general obligations of state and local governments and the remaining 58 percent were revenue based. Eighty-six percent of our municipal fixed income securities were rated AA or better while 99 percent were rated A or better. ​ Equity Securities ​ Our equity portfolio consists of common stocks and exchange traded funds (ETF). Gross unrealized losses in the equity portfolio decreased $8.1 million to $2.0 million in 2019 as equity markets improved during the year. ​ Impairment Analysis ​ Under current accounting standards, an OTTI write-down of debt securities, where fair value is below amortized cost, is triggered by circumstances where: (1) an entity has the intent to sell a security, (2) it is more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis or (3) the entity does not expect to recover the entire amortized cost basis of the security. If an entity intends to sell a security or if it is more likely than not the entity will be required to sell the security before recovery, an OTTI write-down is recognized in earnings equal to the difference between the security’s amortized cost and its fair value. If an entity does not intend to sell the security or it is not more likely than not that it will be required to sell the security before recovery, the OTTI write-down is separated into an amount representing the credit loss, which is recognized in net earnings, and the amount related to all other factors, which is recognized in other comprehensive income. ​ As part of our evaluation of whether particular securities are other-than-temporarily impaired, we consider our intent to sell a security (which is determined on a security-by-security basis) and whether it is more likely than not we will be required to sell the security before the recovery of our amortized cost basis. Significant changes in these factors could result in a charge to net earnings for impairment losses. Impairment losses result in a reduction of the underlying investment’s cost basis. ​ The following table is also used as part of our impairment analysis and displays the total value of debt securities that were in an unrealized loss position as of December 31, 2019, and December 31, 2018. The table segregates the securities based on type, noting the fair value, amortized cost and unrealized loss on each category of investment as well as in total. The table further classifies the securities based on the length of time they have been in an unrealized loss position. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 ​ December 31, 2018 ​ ​ ​ 12 Mos. ​ ​ ​ ​ 12 Mos. ​ ​ (in thousands) ​ < 12 Mos. ​ & Greater ​ Total ​ < 12 Mos. ​ & Greater ​ Total U.S. government ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 2,505 ​ $ 8,463 ​ $ 10,968 ​ $ 7,249 ​ $ 76,073 ​ $ 83,322 ​ Amortized cost ​ 2,506 ​ 8,494 ​ 11,000 ​ 7,270 ​ 77,037 ​ 84,307 ​ Unrealized loss ​ $ (1) ​ $ (31) ​ $ (32) ​ $ (21) ​ $ (964) ​ $ (985) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. agency ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 6,794 ​ $ — ​ $ 6,794 ​ $ — ​ $ 8,843 ​ $ 8,843 ​ Amortized cost ​ 6,836 ​ — ​ 6,836 ​ — ​ 9,058 ​ 9,058 ​ Unrealized loss ​ $ (42) ​ $ — ​ $ (42) ​ $ — ​ $ (215) ​ $ (215) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-U.S. government & agency ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ — ​ $ — ​ $ — ​ $ 5,432 ​ $ 2,207 ​ $ 7,639 ​ Amortized cost ​ — ​ — ​ — ​ 5,571 ​ 2,599 ​ 8,170 ​ Unrealized loss ​ $ — ​ $ — ​ $ — ​ $ (139) ​ $ (392) ​ $ (531) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Agency MBS ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 21,548 ​ $ 41,718 ​ $ 63,266 ​ $ 25,345 ​ $ 261,325 ​ $ 286,670 ​ Amortized cost ​ 21,664 ​ 42,165 ​ 63,829 ​ 25,486 ​ 270,632 ​ 296,118 ​ Unrealized loss ​ $ (116) ​ $ (447) ​ $ (563) ​ $ (141) ​ $ (9,307) ​ $ (9,448) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ABS/CMBS/MBS* ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 74,968 ​ $ 18,036 ​ $ 93,004 ​ $ 46,918 ​ $ 32,137 ​ $ 79,055 ​ Amortized cost ​ 75,332 ​ 18,148 ​ 93,480 ​ 47,146 ​ 32,785 ​ 79,931 ​ Unrealized loss ​ $ (364) ​ $ (112) ​ $ (476) ​ $ (228) ​ $ (648) ​ $ (876) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 16,478 ​ $ 9,348 ​ $ 25,826 ​ $ 306,177 ​ $ 147,751 ​ $ 453,928 ​ Amortized cost ​ 16,950 ​ 9,694 ​ 26,644 ​ 315,428 ​ 154,624 ​ 470,052 ​ Unrealized loss ​ $ (472) ​ $ (346) ​ $ (818) ​ $ (9,251) ​ $ (6,873) ​ $ (16,124) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Municipal ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 47,018 ​ $ — ​ $ 47,018 ​ $ 6,036 ​ $ 55,681 ​ $ 61,717 ​ Amortized cost ​ 47,740 ​ — ​ 47,740 ​ 6,052 ​ 56,975 ​ 63,027 ​ Unrealized loss ​ $ (722) ​ $ — ​ $ (722) ​ $ (16) ​ $ (1,294) ​ $ (1,310) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed income ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 169,311 ​ $ 77,565 ​ $ 246,876 ​ $ 397,157 ​ $ 584,017 ​ $ 981,174 ​ Amortized cost ​ 171,028 ​ 78,501 ​ 249,529 ​ 406,953 ​ 603,710 ​ 1,010,663 ​ Unrealized loss ​ $ (1,717) ​ $ (936) ​ $ (2,653) ​ $ (9,796) ​ $ (19,693) ​ $ (29,489) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ *Non-agency asset-backed and commercial mortgage-backed ​ The fixed income portfolio contained 154 securities in an unrealized loss position as of December 31, 2019. Of these 154 securities, 65 have been in an unrealized loss position for 12 consecutive months or longer and represent $0.9 million in unrealized losses. All fixed income securities continue to pay the expected coupon payments under the contractual terms of the securities. Credit-related impairments on fixed income securities that we do not plan to sell, and for which we are not more likely than not to be required to sell, are recognized in net earnings. Any non-credit related impairment is recognized in comprehensive earnings. Based on our analysis, our fixed income portfolio is of a high credit quality and we believe we will recover the amortized cost basis of our fixed income securities. We continually monitor the credit quality of our fixed income investments to assess if it is probable that we will receive our contractual or estimated cash flows in the form of principal and interest. Key factors that we consider in the evaluation of credit quality include: ​ ● Changes in technology that may impair the earnings potential of the investment, ● The discontinuance of a segment of business that may affect future earnings potential, ● Reduction or elimination of dividends, ● Specific concerns related to the issuer’s industry or geographic area of operation, ● Significant or recurring operating losses, poor cash flows and/or deteriorating liquidity ratios and ● Downgrades in credit quality by a major rating agency. ​ Based on our analysis, we concluded that the securities in an unrealized loss position were not other-than-temporarily impaired at December 31, 2019 and 2018, but were related to changes in interest rates and other related factors. There were no losses associated with OTTI in 2019. There were $0.2 million and $2.6 million in losses associated with OTTI of securities in 2018 and 2017, respectively, that we no longer had the intent to hold. ​ Unrealized Gains and Losses on Equity Securities ​ Net unrealized gains recognized during 2019 on equity securities still held as of December 31, 2019 were $92.8 million. Net unrealized losses recognized during 2018 on equity securities still held as of December 31, 2018 were $28.7 million. Net unrealized gains recognized during 2017 on equity securities still held as of December 31, 2017 were $47.2 million. ​ Other Invested Assets ​ We had $70.4 million of other invested assets at December 31, 2019, compared to $51.5 million at the end of 2018. Other invested assets include investments in low income housing tax credit (LIHTC) partnerships, membership stock in the Federal Home Loan Bank of Chicago (FHLBC) and investments in private funds. Our LIHTC investments are carried at amortized cost and our investment in FHLBC stock is carried at cost. Due to the nature of the LIHTC and our membership in the FHLBC, their carrying amounts approximate fair value. The private funds are carried at fair value, using each investments’ net asset value. ​ Our LIHTC interests had a balance of $23.3 million at December 31, 2019, compared to $20.3 million at December 31, 2018, and recognized a total tax benefit of $2.5 million during 2019, compared to $2.2 million during 2018 and $2.4 million during 2017. Our unfunded commitment for our LIHTC investments totaled $8.6 million at December 31, 2019 and will be paid out in installments through 2035. ​ Our investments in private funds totaled $46.0 million at December 31, 2019, compared to $30.3 million at December 31, 2018, and we had $15.5 million of associated unfunded commitments at December 31, 2019. Our interest in these investments is generally restricted from being transferred or otherwise redeemed without prior consent by the respective entities. An initial public offering would allow for the transfer of interest in some situations, while the timed dissolution of the partnership would trigger redemption in others. ​ Restricted Assets ​ As of December 31, 2019, $15.5 million of investments were pledged as collateral with the FHLBC to ensure timely access to the secured lending facility that ownership of the FHLBC stock provides. As of and during year ended December 31, 2019, there were no outstanding borrowings with the FHLBC. ​ As of December 31, 2019, fixed income securities with a carrying value of $69.6 million were on deposit with regulatory authorities as required by law.

POLICY ACQUISITION COSTS

POLICY ACQUISITION COSTS	12 Months Ended
	Dec. 31, 2019
POLICY ACQUISITION COSTS
POLICY ACQUISITION COSTS	3. POLICY ACQUISITION COSTS ​ Policy acquisition costs deferred and amortized to income for the years ended December 31 are summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Deferred policy acquisition costs (DAC), beginning of year ​ $ 84,934 ​ $ 77,716 ​ $ 73,147 ​ Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Direct commissions ​ $ 185,164 ​ $ 175,697 ​ $ 157,723 ​ Premium taxes ​ 14,395 ​ 12,654 ​ 11,651 ​ Ceding commissions ​ (31,140) ​ (22,190) ​ (18,096) ​ Net deferred ​ $ 168,419 ​ $ 166,161 ​ $ 151,278 ​ Amortized ​ 168,309 ​ 158,943 ​ 146,709 ​ DAC, end of year ​ $ 85,044 ​ $ 84,934 ​ $ 77,716 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Policy acquisition costs: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized to expense - DAC ​ $ 168,309 ​ $ 158,943 ​ $ 146,709 ​ Period costs: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ceding commission - contingent ​ (3,034) ​ (2,241) ​ (3,575) ​ Other underwriting expenses ​ 123,422 ​ 111,036 ​ 109,381 ​ Total policy acquisition costs ​ $ 288,697 ​ $ 267,738 ​ $ 252,515 ​ ​

DEBT

DEBT	12 Months Ended
	Dec. 31, 2019
DEBT
DEBT	4. DEBT ​ As of December 31, 2019, outstanding debt balances totaled $149.3 million, net of unamortized discount and debt issuance costs, all of which were our long-term senior notes. ​ On October 2, 2013, we completed a public debt offering, issuing $150.0 million in senior notes maturing September 15, 2023, and paying interest semi-annually at the rate of 4.875 percent. The notes were issued at a discount resulting in proceeds, net of discount and commission, of $148.6 million. The amount of the discount is being charged to income over the life of the debt on an effective-yield basis. The estimated fair value for the senior note was $161.2 million as of December 31, 2019. The fair value of our long-term debt is based on the limited observable prices that reflect thinly traded securities and is therefore classified as a Level 2 liability within the fair value hierarchy. ​ We paid $7.3 million of interest on our senior notes in each of the last three years. The average rate on debt was 4.91 percent in 2019, 2018 and 2017. ​ We maintain a revolving line of credit with JP Morgan Chase Bank N.A., which permits the Company to borrow up to an aggregate principal amount of $50.0 million. Under certain conditions, the line may be increased up to an aggregate principal amount of $75.0 million. This facility has a two-year term that expires on May 24, 2020. As of and during the years ended December 31, 2019, 2018 and 2017, no amounts were outstanding on these facilities.

REINSURANCE

REINSURANCE	12 Months Ended
	Dec. 31, 2019
REINSURANCE
REINSURANCE	5. REINSURANCE ​ In the ordinary course of business, our insurance subsidiaries assume and cede premiums and selected insured risks with other insurance companies, known as reinsurance. A large portion of the reinsurance is put into effect under contracts known as treaties and, in some instances, by negotiation on each individual risk (known as facultative reinsurance). In addition, there are several types of treaties including quota share, excess of loss and catastrophe reinsurance contracts that protect against losses over stipulated amounts arising from any one occurrence or event. The arrangements allow the Company to pursue greater diversification of business and serve to limit the maximum net loss to a single event, such as a catastrophe. Through the quantification of exposed policy limits in each region and the extensive use of computer-assisted modeling techniques, we monitor the concentration of risks exposed to catastrophic events. ​ Through the purchase of reinsurance, we also generally limit our net loss on any individual risk to a maximum of $3.0 million, although retentions can vary. ​ Premiums written and earned along with losses and settlement expenses incurred for the years ended December 31 are summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 WRITTEN ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Direct $ 1,039,955 $ 934,913 $ 848,153 ​ Reinsurance assumed ​ 25,047 ​ 48,303 ​ 37,159 ​ Reinsurance ceded ​ (204,665) ​ (160,041) ​ (135,458) ​ Net ​ $ 860,337 ​ $ 823,175 ​ $ 749,854 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ EARNED ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Direct ​ $ 981,121 ​ $ 896,234 ​ $ 835,118 ​ Reinsurance assumed ​ 40,173 ​ 41,926 ​ 32,521 ​ Reinsurance ceded ​ (182,183) ​ (146,794) ​ (129,702) ​ Net ​ $ 839,111 ​ $ 791,366 ​ $ 737,937 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ LOSSES AND SETTLEMENT EXPENSES INCURRED ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Direct ​ $ 521,055 ​ $ 560,421 ​ $ 486,986 ​ Reinsurance assumed ​ 21,951 ​ 20,376 ​ 16,072 ​ Reinsurance ceded ​ (129,590) ​ (152,604) ​ (101,474) ​ Net ​ $ 413,416 ​ $ 428,193 ​ $ 401,584 ​ ​ At December 31, 2019, we had unearned reinsurance premiums and recoverables on paid and unpaid losses and settlement expenses totaling $469.2 million, net of collateral. More than 94 percent of our reinsurance recoverables are due from companies with financial strength ratings of A or better by AM Best and S&P rating services. ​ The following table displays net reinsurance balances recoverable, after consideration of collateral, from our top reinsurers as of December 31, 2019. These reinsurers all have financial strength ratings of A or better by AM Best and S&P’s ratings services. Also shown are the amounts of written premium ceded to these reinsurers during the calendar year 2019. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Reinsurer ​ Ceded ​ ​ AM Best ​ S & P ​ Exposure as of ​ Percent of ​ ​ Premiums ​ Percent of (dollars in thousands) ​ Rating ​ Rating ​ 12/31/2019 ​ Total ​ ​ Written ​ Total Munich Re / HSB A+, Superior AA-, Very Strong ​ $ 68,368 14.6 % ​ $ 22,536 11.0 % Swiss Re / Westport Ins. Corp. A+, Superior AA-, Very Strong ​ 34,777 7.4 % ​ 2,801 1.4 % Endurance Re A+, Superior A+, Strong ​ 32,233 6.9 % ​ 9,173 4.5 % Aspen UK Ltd. A, Excellent A, Strong ​ 31,622 6.7 % ​ 8,270 4.0 % Berkley Insurance Co. A+, Superior A+, Strong ​ 28,798 6.1 % ​ 8,667 4.2 % Renaissance Re ​ A+, Superior A+, Strong ​ ​ 25,841 ​ 5.5 % ​ ​ 15,754 ​ 7.7 % Hannover Ruckversicherung A+, Superior AA-, Very Strong ​ 24,758 5.3 % ​ 12,491 6.1 % Toa Re ​ A, Excellent ​ A+, Strong ​ 23,734 5.1 % ​ 7,757 3.8 % Transatlantic Re A+, Superior A+, Strong ​ 22,873 4.9 % ​ 6,635 3.2 % General Re A++, Superior AA+, Very Strong ​ 19,736 4.2 % ​ 6,240 3.0 % Liberty Mutual ​ A, Excellent ​ A, Strong ​ ​ 19,171 ​ 4.1 % ​ ​ 6,696 ​ 3.3 % All other reinsurers* ​ ​ ​ ​ ​ 137,240 29.2 % ​ 97,645 47.8 % Total ceded exposure ​ ​ ​ ​ ​ $ 469,151 100.0 % ​ $ 204,665 100.0 % * ​ Ceded unearned premiums and reinsurance balances recoverable on unpaid losses and settlement expenses are reported separately as an asset, rather than being netted with the related liability, since reinsurance does not relieve the Company of our liability to policyholders. Such balances are subject to the credit risk associated with the individual reinsurer. We continually monitor the financial condition of our reinsurers and actively follow up on any past due or disputed amounts. As part of our monitoring efforts, we review their annual financial statements and SEC filings for those reinsurers that are publicly traded. We also review insurance industry developments that may impact the financial condition of our reinsurers. We analyze the credit risk associated with our reinsurance balances recoverable by monitoring the AM Best and S&P ratings of our reinsurers. In addition, we subject our reinsurance recoverables to detailed recoverability tests, including a segment-based analysis using the average default rating percentage by S&P rating, which assists the Company in assessing the sufficiency of the existing allowance. Additionally, we perform an in-depth reinsurer financial condition analysis prior to the renewal of our reinsurance placements. ​ Our policy is to charge to earnings, in the form of an allowance, an estimate of unrecoverable amounts from reinsurers. This allowance is reviewed on an ongoing basis to ensure that the amount makes a reasonable provision for reinsurance balances that we may be unable to recover. Once regulatory action (such as receivership, finding of insolvency, order of conservation or order of liquidation) is taken against a reinsurer, the paid and unpaid recoverable for the reinsurer are specifically identified and written off through the use of our allowance for estimated unrecoverable amounts from reinsurers. When we write-off such a balance, it is done in full. We then re-evaluate the remaining allowance and determine whether the balance is sufficient as detailed above and if needed, an additional allowance is recognized and income charged. The amounts of allowances for uncollectible amounts on paid and unpaid recoverables were $15.7 million and $9.4 million, respectively, at December 31, 2019. At December 31, 2018, the amounts were $16.1 million and $9.8 million, respectively. We have no receivables with a due date that extends beyond one year that are not included in our allowance for uncollectible amounts.

HISTORICAL LOSS AND LAE DEVELOP

HISTORICAL LOSS AND LAE DEVELOPMENT	12 Months Ended
	Dec. 31, 2019
HISTORICAL LOSS AND LAE DEVELOPMENT
HISTORICAL LOSS AND LAE DEVELOPMENT	6. HISTORICAL LOSS AND LAE DEVELOPMENT ​ The following table is a reconciliation of our unpaid losses and settlement expenses (LAE) for the years 2019, 2018 and 2017: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Unpaid losses and LAE at beginning of year: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ $ 1,461,348 ​ $ 1,271,503 ​ $ 1,139,337 ​ Ceded ​ (364,999) ​ (301,991) ​ (288,224) ​ Net ​ $ 1,096,349 ​ $ 969,512 ​ $ 851,113 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Increase (decrease) in incurred losses and LAE: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current accident year ​ $ 488,700 ​ $ 478,143 ​ $ 440,452 ​ Prior accident years ​ (75,284) ​ (49,950) ​ (38,868) ​ Total incurred ​ $ 413,416 ​ $ 428,193 ​ $ 401,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss and LAE payments for claims incurred: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current accident year ​ $ (80,055) ​ $ (76,050) ​ $ (73,392) ​ Prior accident year ​ (239,875) ​ (225,306) ​ (209,793) ​ Total paid ​ $ (319,930) ​ $ (301,356) ​ $ (283,185) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unpaid losses and LAE at end of year ​ $ 1,189,835 ​ $ 1,096,349 ​ $ 969,512 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unpaid losses and LAE at end of year: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ $ 1,574,352 ​ $ 1,461,348 ​ $ 1,271,503 ​ Ceded ​ (384,517) ​ (364,999) ​ (301,991) ​ Net ​ $ 1,189,835 ​ $ 1,096,349 ​ $ 969,512 ​ ​ Loss development occurs when our current estimate of ultimate losses, established through our reserve analysis processes, differs from the initial reserve estimate. The recognition of the changes in initial reserve estimates occurred over time as claims were reported, initial case reserves were established, initial reserves were reviewed in light of additional information and ultimate payments were made on the collective set of claims incurred as of that evaluation date. The new information on the ultimate settlement value of claims is continually updated until all claims in a defined set are settled. As a small specialty insurer with a diversified product portfolio, our experience will ordinarily exhibit fluctuations from period to period. While we attempt to identify and react to systematic changes in the loss environment, we also must consider the volume of claim experience directly available to the Company and interpret any particular period’s indications with a realistic technical understanding of the reliability of those observations. ​ The following is information about incurred and paid loss development as of December 31, 2019, net of reinsurance, as well as cumulative claim frequency, the total of IBNR liabilities included within the net incurred loss amounts and average historical claims duration as of December 31, 2019. The loss information has been disaggregated so that only losses that are expected to develop in a similar manner are grouped together. This has resulted in the presentation of loss information for our property and surety segments at the segment level, while information for our casualty segment has been separated in four groupings: primary occurrence, excess occurrence, claims made and transportation. Primary occurrence includes select lines within the professional services product along with general liability, small commercial and other casualty products. Excess occurrence encompasses commercial excess and personal umbrella, while claims made includes select lines within the professional services product, executive products and other casualty. Reported claim counts represent claim events on a specified policy rather than individual claimants and includes claims that did not or are not expected to result in an incurred loss. The information about incurred and paid claims development for the years ended December 31, 2010 to 2018 is presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty - Primary Occurrence ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 87,875 $ 96,582 $ 93,589 $ 88,820 $ 85,034 $ 80,289 $ 78,685 $ 78,991 $ 80,216 $ 79,656 ​ $ 1,922 ​ 6,128 2011 ​ ​ ​ ​ 91,139 ​ 98,428 ​ 94,145 ​ 89,622 ​ 86,342 ​ 83,181 ​ 82,193 ​ 82,248 ​ 81,579 ​ ​ 2,546 ​ 5,862 2012 ​ ​ ​ ​ ​ ​ 91,807 ​ 78,406 ​ 65,893 ​ 61,072 ​ 59,028 ​ 59,488 ​ 60,328 ​ 60,465 ​ ​ 2,922 ​ 5,179 2013 ​ ​ ​ ​ ​ ​ ​ ​ 80,823 ​ 67,297 ​ 62,882 ​ 60,329 ​ 60,162 ​ 59,556 ​ 59,116 ​ ​ 4,917 ​ 4,307 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 88,092 ​ 79,497 ​ 71,592 ​ 67,237 ​ 66,389 ​ 66,702 ​ ​ 8,251 ​ 4,266 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 94,835 ​ 84,975 ​ 83,579 ​ 78,675 ​ 76,398 ​ ​ 14,891 ​ 4,362 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 101,950 ​ 96,753 ​ 90,611 ​ 85,449 ​ ​ 24,712 ​ 4,240 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 119,741 ​ 111,391 ​ 102,583 ​ ​ 46,557 ​ 4,336 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 141,513 ​ 130,281 ​ ​ 79,489 ​ 4,490 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 146,011 ​ ​ 119,051 ​ 4,193 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 888,240 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 2,587 $ 13,025 $ 29,312 $ 44,051 $ 55,992 $ 61,929 $ 66,399 $ 69,514 $ 73,318 $ 75,007 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 5,924 ​ 17,124 ​ 32,978 ​ 48,822 ​ 60,769 ​ 67,358 ​ 71,413 ​ 74,814 ​ 76,318 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 5,897 ​ 14,539 ​ 23,889 ​ 33,822 ​ 43,276 ​ 47,970 ​ 51,611 ​ 54,391 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 6,334 ​ 13,021 ​ 22,366 ​ 34,786 ​ 40,609 ​ 45,753 ​ 47,783 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 11,436 ​ 18,771 ​ 29,545 ​ 40,270 ​ 47,343 ​ 52,387 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,157 ​ 19,902 ​ 33,020 ​ 45,056 ​ 54,270 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,142 ​ 24,186 ​ 35,764 ​ 48,042 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 13,154 ​ 25,933 ​ 38,783 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 15,066 ​ 32,365 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 15,698 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 495,044 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 10,714 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 403,910 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 10.8 % 13.2 % 16.3 % 17.4 % 13.0 % 7.9 % 5.0 % 4.2 % 3.3 % 2.1 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty - Excess Occurrence ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 29,314 $ 24,244 $ 22,111 $ 18,932 $ 20,044 $ 22,044 $ 21,018 $ 20,530 $ 20,527 $ 20,579 ​ $ 315 ​ 503 2011 ​ ​ ​ ​ 26,272 ​ 17,148 ​ 17,443 ​ 18,641 ​ 19,160 ​ 20,959 ​ 21,295 ​ 22,032 ​ 21,825 ​ ​ 625 ​ 581 2012 ​ ​ ​ ​ ​ ​ 29,042 ​ 21,558 ​ 21,021 ​ 21,885 ​ 21,231 ​ 22,433 ​ 23,020 ​ 25,286 ​ ​ 1,016 ​ 858 2013 ​ ​ ​ ​ ​ ​ ​ ​ 39,984 ​ 34,824 ​ 26,857 ​ 25,425 ​ 25,599 ​ 24,922 ​ 25,496 ​ ​ 2,220 ​ 939 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 50,889 ​ 39,095 ​ 35,119 ​ 32,274 ​ 33,372 ​ 33,458 ​ ​ 6,322 ​ 887 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 53,672 ​ 50,857 ​ 47,392 ​ 42,840 ​ 43,328 ​ ​ 10,833 ​ 685 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 56,341 ​ 49,385 ​ 37,676 ​ 33,125 ​ ​ 18,457 ​ 624 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 62,863 ​ 55,868 ​ 48,363 ​ ​ 31,333 ​ 563 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 69,362 ​ 62,646 ​ ​ 51,501 ​ 452 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 88,078 ​ ​ 66,592 ​ 293 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 402,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 7 $ 6,002 $ 10,705 $ 13,282 $ 15,512 $ 17,302 $ 19,175 $ 19,256 $ 19,308 $ 19,390 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 2,169 ​ 5,145 ​ 6,981 ​ 8,793 ​ 10,772 ​ 16,494 ​ 17,769 ​ 20,214 ​ 21,036 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 1,315 ​ 3,573 ​ 8,843 ​ 15,380 ​ 16,879 ​ 17,747 ​ 19,310 ​ 21,993 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 1,060 ​ 5,701 ​ 10,967 ​ 14,545 ​ 16,967 ​ 17,956 ​ 18,524 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,899 ​ 4,006 ​ 11,002 ​ 18,852 ​ 22,541 ​ 23,376 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,048 ​ 10,127 ​ 19,571 ​ 23,184 ​ 28,756 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,068 ​ 3,396 ​ 7,441 ​ 10,054 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 17 ​ 5,679 ​ 9,275 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,506 ​ 5,823 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,213 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 162,440 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 16,409 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 256,153 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 4.2 % 13.2 % 16.9 % 14.3 % 9.9 % 8.9 % 5.8 % 7.4 % 2.0 % 0.4 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty - Claims Made ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 13,690 $ 15,556 $ 9,776 $ 10,429 $ 11,689 $ 10,581 $ 9,175 $ 9,024 $ 8,735 $ 8,680 ​ $ 160 ​ 502 2011 ​ ​ ​ ​ 17,416 ​ 17,454 ​ 12,260 ​ 10,619 ​ 8,510 ​ 7,720 ​ 7,852 ​ 11,506 ​ 14,031 ​ ​ 592 ​ 682 2012 ​ ​ ​ ​ ​ ​ 27,576 ​ 26,144 ​ 20,727 ​ 19,590 ​ 18,022 ​ 17,612 ​ 17,569 ​ 20,785 ​ ​ 1,781 ​ 803 2013 ​ ​ ​ ​ ​ ​ ​ ​ 40,095 ​ 41,488 ​ 44,054 ​ 40,288 ​ 38,473 ​ 37,959 ​ 38,352 ​ ​ 2,255 ​ 1,042 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 53,929 ​ 55,386 ​ 58,152 ​ 55,350 ​ 51,554 ​ 53,841 ​ ​ 4,391 ​ 1,305 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 55,006 ​ 47,831 ​ 42,206 ​ 39,906 ​ 39,653 ​ ​ 6,376 ​ 1,336 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 59,992 ​ 67,760 ​ 69,493 ​ 67,728 ​ ​ 16,541 ​ 1,506 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 60,572 ​ 62,450 ​ 62,714 ​ ​ 24,377 ​ 1,633 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 66,128 ​ 62,416 ​ ​ 37,809 ​ 1,381 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 62,918 ​ ​ 50,178 ​ 1,411 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 431,118 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 259 $ 1,548 $ 2,308 $ 3,626 $ 5,733 $ 5,749 $ 6,956 $ 8,485 $ 8,512 $ 8,515 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 330 ​ 1,949 ​ 4,508 ​ 5,947 ​ 5,637 ​ 6,209 ​ 6,835 ​ 7,132 ​ 7,239 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 433 ​ 4,086 ​ 6,898 ​ 9,218 ​ 10,968 ​ 14,378 ​ 15,621 ​ 16,450 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 792 ​ 7,073 ​ 18,425 ​ 26,121 ​ 29,678 ​ 32,789 ​ 34,535 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,705 ​ 9,775 ​ 27,923 ​ 35,755 ​ 40,080 ​ 44,127 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,215 ​ 10,738 ​ 16,774 ​ 20,920 ​ 28,795 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,060 ​ 14,558 ​ 27,465 ​ 39,370 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,455 ​ 11,350 ​ 22,728 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,964 ​ 11,965 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,839 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 215,563 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 2,399 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 217,954 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 3.1 % 16.2 % 19.5 % 14.2 % 11.3 % 7.3 % 7.2 % 7.9 % 0.5 % 0.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty - Transportation ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 27,239 $ 23,390 $ 24,912 $ 25,593 $ 23,981 $ 23,625 $ 23,701 $ 23,786 $ 23,776 $ 23,860 ​ $ 23 ​ 2,843 2011 ​ ​ ​ ​ 22,957 ​ 23,479 ​ 25,747 ​ 25,272 ​ 25,431 ​ 25,376 ​ 25,167 ​ 25,614 ​ 25,827 ​ ​ 41 ​ 2,469 2012 ​ ​ ​ ​ ​ ​ 21,452 ​ 22,203 ​ 22,924 ​ 23,511 ​ 23,689 ​ 23,620 ​ 23,305 ​ 23,731 ​ ​ 47 ​ 2,285 2013 ​ ​ ​ ​ ​ ​ ​ ​ 32,742 ​ 32,853 ​ 32,989 ​ 37,673 ​ 38,811 ​ 39,974 ​ 39,309 ​ ​ 140 ​ 2,853 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 38,361 ​ 33,015 ​ 36,452 ​ 38,590 ​ 40,202 ​ 40,508 ​ ​ 458 ​ 3,099 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 38,561 ​ 46,258 ​ 47,021 ​ 46,395 ​ 45,162 ​ ​ 1,574 ​ 3,183 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 50,430 ​ 53,519 ​ 54,105 ​ 52,277 ​ ​ 4,241 ​ 3,935 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 55,640 ​ 53,641 ​ 45,017 ​ ​ 7,476 ​ 3,625 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 57,597 ​ 54,592 ​ ​ 24,385 ​ 3,376 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 58,297 ​ ​ 17,932 ​ 3,082 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 408,580 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 6,296 $ 10,116 $ 15,475 $ 20,045 $ 21,792 $ 23,063 $ 23,488 $ 23,533 $ 23,556 $ 23,635 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 5,295 ​ 9,485 ​ 14,477 ​ 19,443 ​ 22,375 ​ 23,537 ​ 23,941 ​ 24,377 ​ 25,052 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 4,466 ​ 8,533 ​ 12,394 ​ 17,318 ​ 20,931 ​ 22,566 ​ 22,730 ​ 23,180 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 5,306 ​ 11,978 ​ 19,761 ​ 28,220 ​ 33,480 ​ 35,923 ​ 37,327 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,125 ​ 13,933 ​ 19,676 ​ 27,457 ​ 33,190 ​ 38,282 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6,984 ​ 20,709 ​ 29,554 ​ 37,222 ​ 39,339 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8,923 ​ 18,354 ​ 30,354 ​ 38,001 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,979 ​ 17,070 ​ 24,090 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6,980 ​ 12,827 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,148 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 268,881 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 252 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 139,951 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 17.2 % 18.1 % 18.8 % 18.8 % 11.0 % 7.1 % 1.9 % 1.3 % 1.4 % 0.3 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Property ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 63,194 $ 59,145 $ 55,427 $ 53,937 $ 54,153 $ 52,927 $ 52,964 $ 52,952 $ 52,903 $ 52,548 ​ $ 10 ​ 2,850 2011 ​ ​ ​ ​ 70,246 ​ 66,924 ​ 64,976 ​ 63,724 ​ 62,770 ​ 62,570 ​ 62,456 ​ 62,875 ​ 62,799 ​ ​ 65 ​ 3,028 2012 ​ ​ ​ ​ ​ ​ 85,485 ​ 80,155 ​ 79,181 ​ 77,569 ​ 79,175 ​ 78,125 ​ 78,161 ​ 78,002 ​ ​ 97 ​ 2,640 2013 ​ ​ ​ ​ ​ ​ ​ ​ 63,864 ​ 62,090 ​ 62,173 ​ 62,114 ​ 61,914 ​ 61,834 ​ 61,776 ​ ​ 183 ​ 2,995 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 56,587 ​ 49,441 ​ 48,801 ​ 48,761 ​ 49,217 ​ 49,444 ​ ​ 158 ​ 4,561 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 59,863 ​ 56,103 ​ 53,958 ​ 52,720 ​ 53,111 ​ ​ 403 ​ 4,075 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 62,900 ​ 55,594 ​ 55,384 ​ 55,930 ​ ​ 1,418 ​ 3,371 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 90,803 ​ 83,273 ​ 84,961 ​ ​ 5,861 ​ 2,883 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 89,091 ​ 83,457 ​ ​ 10,867 ​ 2,321 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 71,232 ​ ​ 27,090 ​ 2,098 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 653,260 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 25,274 $ 43,091 $ 47,743 $ 50,055 $ 52,729 $ 52,426 $ 52,719 $ 52,851 $ 52,855 $ 52,538 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 27,676 ​ 48,756 ​ 55,778 ​ 59,099 ​ 60,272 ​ 61,428 ​ 61,834 ​ 62,729 ​ 62,730 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 39,074 ​ 66,509 ​ 72,057 ​ 73,705 ​ 75,640 ​ 76,152 ​ 77,159 ​ 77,323 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 32,208 ​ 50,840 ​ 57,407 ​ 59,259 ​ 60,520 ​ 61,195 ​ 61,325 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 30,550 ​ 43,380 ​ 46,148 ​ 46,528 ​ 47,799 ​ 49,027 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 32,184 ​ 49,348 ​ 50,197 ​ 51,290 ​ 52,078 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 33,134 ​ 46,921 ​ 51,371 ​ 53,006 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 41,314 ​ 66,818 ​ 74,415 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 37,048 ​ 68,264 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 30,703 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 581,409 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 114 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 71,965 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 51.2 % 31.5 % 7.7 % 2.9 % 2.6 % 1.1 % 0.7 % 0.6 % 0.0 % (0.6) % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Surety ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 13,961 $ 8,205 $ 6,630 $ 7,076 $ 6,810 $ 7,136 $ 7,645 $ 6,244 $ 6,580 $ 6,743 ​ $ 47 ​ 1,543 2011 ​ ​ ​ ​ 13,842 ​ 17,832 ​ 17,792 ​ 17,321 ​ 16,766 ​ 16,695 ​ 16,480 ​ 18,281 ​ 18,293 ​ ​ 35 ​ 1,679 2012 ​ ​ ​ ​ ​ ​ 17,114 ​ 11,452 ​ 8,667 ​ 8,180 ​ 7,867 ​ 7,471 ​ 7,099 ​ 7,082 ​ ​ 38 ​ 1,474 2013 ​ ​ ​ ​ ​ ​ ​ ​ 16,080 ​ 7,516 ​ 6,170 ​ 5,399 ​ 5,271 ​ 5,231 ​ 5,209 ​ ​ 65 ​ 1,406 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 16,450 ​ 8,106 ​ 5,225 ​ 4,427 ​ 4,267 ​ 4,319 ​ ​ 67 ​ 1,346 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 16,958 ​ 12,957 ​ 11,113 ​ 10,456 ​ 9,792 ​ ​ 384 ​ 1,217 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 18,928 ​ 11,062 ​ 9,351 ​ 8,895 ​ ​ 742 ​ 1,359 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 16,127 ​ 8,641 ​ 8,798 ​ ​ 1,469 ​ 1,645 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 16,765 ​ 7,227 ​ ​ 3,965 ​ 1,157 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14,785 ​ ​ 14,035 ​ 607 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 91,143 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 1,724 $ 3,205 $ 5,702 $ 7,092 $ 7,151 $ 7,285 $ 7,822 $ 6,663 $ 6,637 $ 6,733 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 8,160 ​ 16,932 ​ 17,151 ​ 17,403 ​ 17,212 ​ 17,086 ​ 17,086 ​ 17,013 ​ 18,251 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 1,883 ​ 6,680 ​ 6,726 ​ 7,416 ​ 7,536 ​ 7,406 ​ 7,065 ​ 6,996 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 1,116 ​ 2,856 ​ 4,701 ​ 4,911 ​ 5,098 ​ 5,150 ​ 5,128 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 722 ​ 4,283 ​ 4,166 ​ 4,059 ​ 4,131 ​ 4,234 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 3,192 ​ 6,719 ​ 7,695 ​ 9,436 ​ 9,183 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 3,087 ​ 5,817 ​ 6,299 ​ 7,640 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 979 ​ 2,862 ​ 7,062 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,835 ​ 2,588 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 336 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 68,151 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 1,996 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 24,988 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 24.1 % 39.1 % 16.8 % 9.4 % 0.7 % 0.6 % 0.7 % (6.2) % 3.2 % 1.4 % ​ ​ ​ ​ ​ The following is a reconciliation of the net incurred and paid loss development tables to the liability for unpaid losses and settlement expenses in the consolidated balance sheet: ​ ​ ​ ​ ​ ​ ​ ​ Reconciliation of Incurred and Paid Loss Development to the Liability for Unpaid Losses and Settlement Expenses (in thousands) ​ December 31, 2019 ​ December 31, 2018 Net outstanding liabilities: ​ ​ ​ ​ ​ ​ Casualty - Primary Occurrence ​ $ 403,910 ​ $ 372,450 Casualty - Excess Occurrence ​ ​ 256,153 ​ ​ 209,683 Casualty - Claims Made ​ ​ 217,954 ​ ​ 204,501 Casualty - Transportation ​ ​ 139,951 ​ ​ 133,558 Property ​ ​ 71,965 ​ ​ 77,238 Surety ​ ​ 24,988 ​ ​ 28,237 Unallocated loss adjustment expenses ​ ​ 52,275 ​ ​ 50,891 Allowance for uncollectible reinsurance balances recoverable on unpaid losses and settlement expenses ​ ​ 9,402 ​ ​ 9,793 Other ​ ​ 13,237 ​ ​ 9,998 Liabilities for unpaid loss and settlement expenses, net of reinsurance ​ $ 1,189,835 ​ $ 1,096,349 ​ ​ ​ ​ ​ ​ ​ Reinsurance recoverable on unpaid claims: ​ ​ ​ ​ ​ ​ Casualty - Primary Occurrence ​ $ 31,122 ​ $ 34,742 Casualty - Excess Occurrence ​ ​ 98,518 ​ ​ 81,072 Casualty - Claims Made ​ ​ 176,936 ​ ​ 144,921 Casualty - Transportation ​ ​ 53,724 ​ ​ 50,748 Property ​ ​ 21,438 ​ ​ 50,495 Surety ​ ​ 11,199 ​ ​ 11,834 Allowance for uncollectible reinsurance balances recoverable on unpaid losses and settlement expenses ​ ​ (9,402) ​ ​ (9,793) Other ​ ​ 982 ​ ​ 980 Total reinsurance balances recoverable on unpaid losses and settlement expenses ​ $ 384,517 ​ $ 364,999 ​ ​ ​ ​ ​ ​ ​ Total gross liability for unpaid loss and settlement expenses ​ $ 1,574,352 ​ $ 1,461,348 ​ DETERMINATION OF IBNR ​ Initial carried IBNR reserves are determined through a reserve estimation process. For most casualty and surety products, this process involves the use of an initial loss and allocated loss adjustment expense (ALAE) ratio that is applied to the earned premium for a given period. Payments and case reserves are subtracted from this initial estimate of ultimate loss and ALAE to determine a carried IBNR reserve. For most property products, the IBNR reserves are determined by IBNR percentages applied to premium earned. The percentages are determined based on historical reporting patterns and are updated periodically. No deductions for paid or case reserves are made. Shortly after natural or man-made catastrophes, we review insured locations exposed to the event and model losses based on our own exposures and industry loss estimates of the event. We also consider our knowledge of frequency and severity from early claim reports to determine an appropriate reserve for the catastrophe. Adjustments to the initial loss ratio by product and segment are made where necessary and reflect updated assumptions regarding loss experience, loss trends, price changes and prevailing risk factors. ​ Actuaries perform a ground-up reserve study of the expected value of the unpaid loss and LAE derived using multiple standard actuarial methodologies on a quarterly basis. Each method produces an estimate of ultimate loss by accident year. We review all of these various estimates and assign weights to each based on the characteristics of the product being reviewed. These estimates are then compared to the carried loss reserves to determine the appropriateness of the current reserve balance. In addition, an emergence analysis is completed quarterly to determine if further adjustments are necessary. ​ Upon completion of our loss and LAE estimation analysis, a review of the resulting variance between the indicated reserves and the carried reserves takes place. Our actuaries make a recommendation to management in regards to booked reserves that reflect their analytical assessment and view of estimation risk. After discussion of these analyses and all relevant risk factors, the Loss Reserve Committee, a panel of management including the lead reserving actuary, chief executive officer, chief operating officer, chief financial officer and other executives, confirms the appropriateness of the reserve balances. ​ DEVELOPMENT OF IBNR RESERVES ​ The following table summarizes our prior accident years’ loss reserve development by segment for 2019, 2018 and 2017: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (FAVORABLE)/UNFAVORABLE RESERVE DEVELOPMENT BY SEGMENT ​ (in thousands) 2019 2018 2017 ​ Casualty ​ $ (62,497) ​ $ (33,252) ​ $ (17,462) ​ Property ​ (4,461) ​ (10,813) ​ (12,134) ​ Surety ​ (8,326) ​ (5,885) ​ (9,272) ​ Total ​ $ (75,284) ​ $ (49,950) ​ $ (38,868) ​ ​ A discussion of significant components of reserve development for the three most recent calendar years follows: ​ 2019. We experienced favorable emergence relative to prior years’ reserve estimates in all of our segments during 2019. The casualty segment contributed $62.5 million in favorable development, inclusive of unallocated loss and adjustment expenses (ULAE) , which is excluded from the incurred loss and loss adjustment expense tables above . Accident years 2017 and 2018 contributed the majority of the favorable development, with earlier years developing favorably in aggregate to a lesser extent. Risk selection by our underwriters continued to provide better results than estimated in our reserving process. Within the primary occurrence grouping, the general liability product contributed $11.8 million to our favorable development. Small commercial products were favorable by $6.3 million. Within the excess occurrence grouping, commercial excess was favorable by $6.8 million and our personal umbrella product developed favorably by $7.8 million. Within the claims made grouping, professional services coverages developed favorably by $10.2 million, which was offset by adverse development of $7.3 million on executive products and $2.3 million on medical professional liability coverages. Transportation experienced favorable development of $16.6 million, primarily on accident years 2016 through 2018. ​ Marine contributed $2.4 million of the $4.5 million total favorable property development, inclusive of ULAE. Accident years 2017 and 2018 contributed to the marine products’ favorable development. Homeowners contributed $1.1 million of favorable development with other commercial property insurance and assumed reinsurance products contributing the balance. ​ The surety segment experienced favorable development of $8.3 million, inclusive of ULAE. The majority of the favorable development was from accident year 2018, while earlier accident years developed slightly adversely. The commercial surety product was the main contributor with favorable development of $5.8 million. Contract surety had favorable development of $4.2 million, which offset $1.7 million of adverse development on miscellaneous surety. ​ 2018. We experienced favorable emergence relative to prior years’ reserve estimates in all of our segments during 2018. Development from the casualty segment totaled $33.3 million, inclusive of ULAE . The largest amounts of favorable development came from accident years 2015 through 2017. We continued to experience emergence that was generally better than previously estimated. We attribute the favorable emergence to loss trends in most lines outperforming our long-term expectations. Further, we believe our underwriters’ risk selection contributed to the Company experiencing less loss cost inflation than originally anticipated. The primary occurrence grouping had favorable development of $15.6 million, driven by our general liability product with $6.7 million of favorable development. The excess occurrence grouping had favorable development of $21.4 million, with commercial insureds contributing $10.8 million and personal insureds contributing the remainder. Claims made exposures had adverse development of $3.9 million driven by medical errors and omissions coverages. Transportation had $0.5 million of favorable development. ​ Our marine product was the predominant driver of the favorable development in the property segment, accounting for $5.0 million of the $10.8 million total favorable development for the segment, inclusive of ULAE. Accident years 2015 through 2017 made the largest contribution. Our excess and surplus lines commercial property product and assumed reinsurance products also contributed $2.0 million and $2.8 million of favorable development, respectively. ​ The surety segment experienced $5.9 million of favorable development, inclusive of ULAE. The majority of the favorable development came from the 2017 accident year, which served to offset the unfavorable development from accident years 2011 and 2016. Commercial surety contributed favorable development of $6.3 million. Miscellaneous surety experienced adverse development totaling $0.8 million. ​ 2017. We experienced favorable emergence relative to prior years’ reserve estimates in all of our segments during 2017. The casualty segment contributed $17.5 million in favorable development, inclusive of ULAE . Accident years 2014, 2015 and 2016 contributed significantly to the favorable development. This was predominantly caused by favorable frequency and severity trends that continued to be better than our long-term expectations. In addition, we believe this to be the result of our underwriters’ risk selection, which has mostly offset price declines and loss cost inflation. Nearly all of our casualty products contributed to the favorable development. Within the primary occurrence grouping, the general liability product contributed $4.6 million to our favorable development with a

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2019
INCOME TAXES
INCOME TAXES	7. INCOME TAXES ​ The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities are summarized below. The adoption of ASU 2016-02, as described in note 1.C., required a right-of-use asset and lease liability be recognized for operating leases in 2019, which resulted in a corresponding deferred tax liability and deferred tax asset. ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Tax discounting of unpaid losses and settlement expenses ​ $ 19,143 ​ $ 18,327 ​ Unearned premium offset ​ 18,755 ​ 17,864 ​ Deferred compensation ​ 2,981 ​ 2,700 ​ Stock option expense ​ 2,728 ​ 2,702 ​ Lease liability ​ 5,140 ​ — ​ Other ​ 275 ​ 616 ​ Deferred tax assets before allowance ​ $ 49,022 ​ $ 42,209 ​ Less valuation allowance ​ — ​ — ​ Total deferred tax assets ​ $ 49,022 ​ $ 42,209 ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Net unrealized appreciation of securities ​ $ 56,532 ​ $ 22,177 ​ Deferred policy acquisition costs ​ 17,859 ​ 17,836 ​ Lease asset ​ ​ 4,690 ​ ​ — ​ Discounting of unpaid losses and settlement expenses - Tax Cuts and Jobs Act (TCJA) implementation offset ​ ​ 3,817 ​ ​ 5,203 ​ Book/tax depreciation ​ 3,008 ​ 3,133 ​ Intangible assets ​ 1,634 ​ 1,711 ​ Undistributed earnings of unconsolidated investees ​ 17,673 ​ 15,811 ​ Other ​ 536 ​ 576 ​ Total deferred tax liabilities ​ $ 105,749 ​ $ 66,447 ​ Net deferred tax liability ​ $ (56,727) ​ $ (24,238) ​ ​ Income tax expense (benefit) attributable to income from operations for the years ended December 31, 2019, 2018 and 2017, differed from the amounts computed by applying the U.S. federal tax rate of 21 percent, 21 percent and 35 percent, respectively, to pretax income from continuing operations as demonstrated in the following table: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Provision for income taxes at the statutory federal tax rates ​ $ 48,874 ​ 21.0 % ​ $ 14,192 ​ 21.0 % ​ $ 29,606 ​ 35.0 % ​ Increase (reduction) in taxes resulting from: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Enactment of TCJA ​ ​ — ​ — % ​ ​ (2,268) ​ (3.4) % ​ ​ (32,821) ​ (38.8) % ​ Excess tax benefit on share-based compensation ​ ​ (3,958) ​ (1.7) % ​ ​ (4,533) ​ (6.7) % ​ ​ (5,798) ​ (6.9) % ​ Dividends received deduction ​ (823) ​ (0.4) % ​ (775) ​ (1.1) % ​ (2,025) ​ (2.4) % ​ ESOP dividends paid deduction ​ (1,122) ​ (0.5) % ​ (1,184) ​ (1.8) % ​ (2,905) ​ (3.4) % ​ Tax-exempt interest income ​ (1,238) ​ (0.5) % ​ (1,795) ​ (2.7) % ​ (4,671) ​ (5.5) % ​ Unconsolidated investee dividends ​ (1,802) ​ (0.8) % ​ — ​ — % ​ (1,351) ​ (1.6) % ​ Nondeductible expenses ​ ​ 1,649 ​ 0.7 % ​ ​ 389 ​ 0.6 % ​ ​ 276 ​ 0.3 % ​ Other items, net ​ (488) ​ (0.1) % ​ (624) ​ (0.9) % ​ (750) ​ (0.9) % ​ Total ​ $ 41,092    ​ 17.7 % ​ $ 3,402    ​ 5.0 % ​ $ (20,439)    ​ (24.2) % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Our effective tax rates were 17.7 percent, 5.0 percent and -24.2 percent for 2019, 2018 and 2017, respectively. Effective rates are dependent upon components of pretax earnings and the related tax effects. The effective rate was higher in 2019 primarily due to higher levels of pretax earnings, which caused the tax-favored adjustments to be smaller on a percentage basis in 2019 compared to 2018. The effective rate was significantly lower in 2017 as a result of the impact of tax reform. ​ Among other provisions, the TCJA lowered the federal corporate tax rate from 35 percent to 21 percent effective January 1, 2018. Our deferred tax items were revalued as of year-end 2017 to reflect the lower rate, which reduced our net deferred tax liability and income tax expense by $32.8 million and decreased the effective tax rate by 38.8 percent. ​ Except for two aspects, the accounting for the tax effects of the enactment of the TCJA were completed as of December 31, 2017. The first provisional item recorded in 2017 was related to an expected disallowance of deductions for certain performance based compensation, including bonuses and stock options. At the time of enactment, there was a lack of clarity on whether some amounts could be grandfathered in as deductible. The Internal Revenue Service (IRS) and Treasury Department provided additional guidance and we were able to finalize the accounting in 2018 by recording a $2.3 million deferred tax benefit to restore the deferred tax assets related to those performance based compensation amounts. The second provisional item related to discount factors on loss reserves that the IRS had not yet published. The IRS published the factors in the fourth quarter of 2018 and we were able to complete the accounting for the effects of the enactment of the TCJA. While there was no net impact to the deferred tax amount that was recorded at December 31, 2017, we implemented the new discounting methodology and will recognize the adjustment ratably over the allowed eight-year period beginning in 2018. ​ Our net earnings include equity in earnings of unconsolidated investees, Maui Jim and Prime. The investees do not have a policy or pattern of paying dividends. As a result, we record a deferred tax liability on the earnings at the recently revised corporate capital gains rate of 21 percent in anticipation of recovering our investments through means other than through the receipt of dividends, such as a sale. We received a $13.2 million dividend from Maui Jim in 2019 and recognized a $1.8 million tax benefit from applying the lower tax rate applicable to affiliated dividends ( 7.4 percent in 2019), as compared to the corporate capital gains rate on which the deferred tax liabilities were based. In the fourth quarter of 2017, Maui Jim gave notification that a $9.9 million dividend would be paid in January 2018. Even though no dividend was received in 2017, we were aware that the lower tax rate applicable to affiliated dividends ( 7.4 percent in 2018) would be applied when the dividend was paid in 2018 and we therefore recorded a $1.4 million tax benefit in 2017. Standing alone, the dividends resulted in a 0.8 percent and 1.6 percent reduction to the 2019 and 2017 effective tax rates, respectively. As no additional dividends were declared from unconsolidated investees in 2018, there was no impact to the 2018 effective tax rate. ​ Dividends paid to our Employee Stock Ownership Plan (ESOP) also result in a tax deduction. Dividends paid to the ESOP in 2019, 2018 and 2017 resulted in tax benefits of $1.1 million, $1.2 million and $2.9 million, respectively. These tax benefits reduced the effective tax rate for 2019, 2018 and 2017 by 0.5 percent, 1.8 percent and 3.4 percent, respectively. ​ We have recorded our deferred tax assets and liabilities using the statutory federal tax rate of 21 percent. We believe it is more likely than not that all deferred tax assets will be recovered, given the carry back availability as well as the results of future operations, which will generate sufficient taxable income to realize the deferred tax asset. In addition, we believe when these deferred items reverse in future years, our taxable income will be taxed at an effective rate of 21 percent. ​ Federal and state income taxes paid in 2019, 2018 and 2017 amounted to $25.6 million, $16.4 million and $10.4 million, respectively. ​ Although we are not currently under audit by the IRS, tax years 2016 through 2019 remain open and are subject to examination.

EMPLOYEE BENEFITS

EMPLOYEE BENEFITS	12 Months Ended
	Dec. 31, 2019
EMPLOYEE BENEFITS
EMPLOYEE BENEFITS	8. EMPLOYEE BENEFITS ​ EMPLOYEE STOCK OWNERSHIP, 401(K) AND INCENTIVE PLANS ​ We maintain ESOP, 401(k) and incentive plans covering executives, managers and associates. Funding of these plans is primarily dependent upon reaching predetermined levels of operating return on equity, combined ratio and Market Value Potential (MVP). MVP is a compensation model that measures components of comprehensive earnings against a minimum required return on our capital. Bonuses are earned as we generate earnings in excess of this required return. While some management incentive plans may be affected somewhat by other performance factors, the larger influence of corporate performance ensures that the interests of our executives, managers and associates align with those of our shareholders. ​ Our 401(k) plan allows voluntary contributions by employees and permits ESOP diversification transfers for employees meeting certain age and service requirements. We provide a basic 401(k) contribution of 3 percent of eligible compensation. Participants are 100 percent vested in both voluntary and basic contributions. Additionally, an annual discretionary profit-sharing contribution may be made to the ESOP and 401(k), subject to the achievement of certain overall financial goals and board approval. Profit-sharing contributions vest after three years of plan service. ​ Our ESOP and 401(k) cover all employees meeting eligibility requirements. ESOP and 401(k) profit-sharing contributions are approved annually by our board of directors and are expensed in the year earned. ESOP and 401(k)-related expenses (basic and profit-sharing) were $15.7 million, $8.8 million and $12.5 million for 2019, 2018 and 2017, respectively. ​ During 2019, the ESOP purchased 60,768 shares of RLI Corp. stock on the open market at an average price of $69.99 ( $4.3 million) relating to the contribution for plan year 2018. Shares held by the ESOP as of December 31, 2019, totaled 2,758,290 and are treated as outstanding in computing our earnings per share. During 2018, the ESOP purchased 98,717 shares of RLI Corp. stock on the open market at an average price of $62.80 ( $6.2 million) relating to the contribution for plan year 2017. During 2017, the ESOP purchased 124,186 shares of RLI Corp. stock on the open market at an average price of $58.02 ( $7.2 million) relating to the contribution for plan year 2016. The above-mentioned ESOP purchases relate only to our annual contributions to the plan and do not include amounts or shares resulting from the reinvestment of dividends. ​ Annual awards are provided to executives, managers and associates through our incentive plans, provided certain strategic and financial goals are met. Annual expenses for these incentive plans totaled $30.1 million, $11.9 million and $19.7 million for 2019, 2018 and 2017, respectively. ​ DEFERRED COMPENSATION ​ We maintain rabbi trusts for deferred compensation plans for directors, key employees and executive officers through which our shares are purchased. The employer stock in the plan is classified and accounted for as equity, in a manner consistent with the accounting for treasury stock. ​ In 2019, the trusts purchased 6,569 shares of our common stock on the open market at an average price of $81.77 ($0.5 million). In 2018, the trusts purchased 7,049 shares of our common stock on the open market at an average price of $68.36 ($0.5 million). In 2017, the trusts purchased 7,464 shares of our common stock on the open market at an average price of $58.66 ($0.4 million). At December 31, 2019, the trusts’ assets were valued at $44.5 million. ​ STOCK PLANS ​ Our RLI Corp. Long-Term Incentive Plan (2010 LTIP) was in place from 2010 to 2015. The 2010 LTIP provided for equity-based compensation, including stock options, up to a maximum of ​ In 2015, our shareholders approved the 2015 RLI Corp. Long-Term Incentive Plan (2015 LTIP), which provides for equity-based compensation and replaced the 2010 LTIP. In conjunction with the adoption of the 2015 LTIP, effective May 7, 2015, options were no longer granted under the 2010 LTIP. Awards under the 2015 LTIP may be in the form of restricted stock, restricted stock units, stock options (non-qualified only), stock appreciation rights, performance units as well as other stock-based awards. Eligibility under the 2015 LTIP is limited to employees and directors of the Company or any affiliate. The granting of awards under the 2015 LTIP is solely at the discretion of the board of directors. The maximum number of shares of common stock available for distribution under the 2015 LTIP is 4,000,000 shares (subject to adjustment for changes in our capitalization and other events). Since the plan’s approval in 2015, we have granted 2,282,460 awards under the 2015 LTIP, including 378,830 in 2019. ​ Stock Options ​ Under the 2015 LTIP, as under the 2010 LTIP, we grant stock options for shares with an exercise price equal to the fair market value of the shares at the date of grant (subject to adjustments for changes in our capitalization, including special dividends and other events as set forth in such plans). Options generally vest and become exercisable ratably over a five-year period and expire eight years after grant. ​ For most participants, the requisite service period and vesting period will be the same. For participants who are retirement eligible, defined by the plan as those individuals whose age and years of service equals 75 , the requisite service period is deemed to be met and options are immediately expensed on the date of grant. For participants who will become retirement eligible during the vesting period, the requisite service period over which expense is recognized is the period between the grant date and the attainment of retirement eligibility. Shares issued upon option exercise are newly issued shares. ​ The following tables summarize option activity in 2019, 2018 and 2017: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Weighted ​ Average ​ Aggregate ​ ​ Number of ​ Average ​ Remaining ​ Intrinsic ​ ​ Options ​ Exercise ​ Contractual ​ Value ​ ​ Outstanding ​ Price ​ Life ​ (in 000’s) Outstanding options at January 1, 2019 ​ 1,964,880 ​ $ 54.24 ​ ​ ​ ​ ​ ​ Options granted ​ 356,900 ​ $ 82.63 ​ ​ ​ ​ ​ ​ Options exercised ​ (533,940) ​ $ 45.96 ​ ​ ​ $ 20,033 ​ Options canceled/forfeited ​ (120,550) ​ $ 60.48 ​ ​ ​ ​ ​ ​ Outstanding options at December 31, 2019 ​ 1,667,290 ​ $ 62.52 5.20 ​ $ 46,051 ​ Exercisable options at December 31, 2019 ​ 642,365 ​ $ 53.93 3.80 ​ $ 23,197 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Weighted ​ Average ​ Aggregate ​ ​ Number of ​ Average ​ Remaining ​ Intrinsic ​ ​ Options ​ Exercise ​ Contractual ​ Value ​ ​ Outstanding ​ Price ​ Life ​ (in 000’s) Outstanding options at January 1, 2018 2,257,015 ​ $ 46.80 ​ ​ ​ ​ ​ ​ Options granted 432,000 ​ $ 64.91 ​ ​ ​ ​ ​ ​ Options exercised (705,785) ​ $ 36.81 ​ ​ ​ $ 24,304 ​ Options canceled/forfeited (18,350) ​ $ 60.84 ​ ​ ​ ​ ​ ​ Outstanding options at December 31, 2018 1,964,880 ​ $ 54.24 5.25 ​ $ 29,317 ​ Exercisable options at December 31, 2018 724,730 ​ $ 46.62 3.79 ​ $ 16,212 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average ​ Aggregate ​ ​ Number of ​ Average Remaining ​ Intrinsic ​ ​ Options ​ Exercise Contractual ​ Value ​ ​ Outstanding Price Life (in 000’s) Outstanding options at January 1, 2017 2,207,110 ​ $ 40.90 ​ ​ ​ ​ ​ ​ Options granted 482,375 ​ $ 57.12 ​ ​ ​ ​ ​ ​ Options exercised (390,870) ​ $ 26.07 ​ ​ ​ $ 12,779 ​ Options canceled/forfeited (41,600) ​ $ 48.30 ​ ​ ​ ​ ​ ​ Outstanding options at December 31, 2017 2,257,015 ​ $ 46.80 4.88 ​ $ 32,620 ​ Exercisable options at December 31, 2017 975,055 ​ $ 38.66 3.25 ​ $ 21,780 ​ ​ The majority of our stock options are granted annually at our regular board meeting in May. In addition, options are approved at the May meeting for quarterly grants to certain retirement eligible employees. Since stock option grants to retirement eligible employees are fully expensed when granted, the approach allows for a more even expense distribution throughout the year. ​ In 2019, 356,900 options were granted with an average exercise price of $82.63 and an average fair value of $13.49 . Of these grants, 251,400 were granted at the board meeting in May with a calculated fair value of $13.65 . We recognized $4.5 million of expense during 2019 related to options vesting. Since options granted under our plan are non-qualified, we recorded a deferred tax benefit of $0.9 million related to this compensation expense. Total unrecognized compensation expense relating to outstanding and unvested options was $4.8 million, which will be recognized over the remainder of the vesting period. ​ In 2018, 432,000 options were granted with an average exercise price of $64.91 and an average fair value of $10.58 . Of these grants, 330,750 were granted at the board meeting in May with a calculated fair value of $10.31 . We recognized $4.5 million of expense during 2018 related to options vesting. Since options granted under our plan are non-qualified, we recorded a deferred tax benefit of $0.9 million related to this compensation expense. Total unrecognized compensation expense relating to outstanding and unvested options was $5.6 million, which will be recognized over the remainder of the vesting period. ​ In 2017, 482,375 options were granted with an average exercise price of $57.12 and an average fair value of $8.00 . Of these grants, 384,750 were granted at the board meeting in May with a calculated fair value of $7.91 . We recognized $4.4 million of expense during 2017 related to options vesting. Since options granted under our plan are non-qualified, we recorded a deferred tax benefit of $1.5 million related to this compensation expense. Total unrecognized compensation expense relating to outstanding and unvested options was $5.7 million, which will be recognized over the remainder of the vesting period. ​ The fair value of options were estimated using a Black-Scholes based option pricing model with the following weighted-average grant-date assumptions and weighted-average fair values as of December 31: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 2018 2017 Weighted-average fair value of grants ​ $ 13.49 ​ $ 10.58 ​ $ 8.00 ​ Risk-free interest rates ​ 2.26 % 2.72 % 1.90 % Dividend yield ​ 2.69 % 2.98 % 3.60 % Expected volatility ​ 22.71 % 22.87 % 22.95 % Expected option life ​ 4.96 years 5.07 years 5.05 years ​ The risk-free rate was determined based on U.S. treasury yields that most closely approximated the option’s expected life. The dividend yield was determined based on the average annualized quarterly dividends paid during the most recent five-year period and incorporated a consideration for special dividends paid in recent history. The expected volatility was calculated based on the median of the rolling volatilities for the expected life of the options. The expected option life was determined based on historical exercise behavior and the assumption that all outstanding options will be exercised at the midpoint of the current date and remaining contractual term, adjusted for the demographics of the current year’s grant. ​ Restricted Stock Units ​ In addition to stock options, restricted stock units (RSUs) are granted with a value equal to the closing stock price of the Company’s stock on the dates the units are granted. These units generally have a three-year cliff vesting, but have an accelerated vesting feature for participants who are retirement eligible, defined by the plan as those individuals whose age and years of service equals 75 . In addition, the RSUs have dividend participation, which accrue as additional units and are settled with granted stock units at the end of the vesting period. ​ As of December 31, 2019, 45,350 RSUs have been granted to employees under the 2015 LTIP, including 15,275 during 2019, and 43,681 remain outstanding. We recognized $0.9 million, $0.6 million and $0.4 million of expense on these units during 2019, 2018 and 2017, respectively. Total unrecognized compensation expense relating to outstanding and unvested employee RSUs was $0.9 million, which will be recognized over the remainder of the vesting period. ​ In 2019 and 2018, each outside director received RSUs with a fair value of $50,000 on the date of grant as part of annual director compensation. Director RSUs vest one year from the date of grant. As of December 31, 2019, 15,085 RSUs were granted to directors under the 2015 LTIP, including 6,655 in 2019, and 6,162 director RSUs remain outstanding. We recognized $0.6 million and $0.3 million of compensation expense on these units during 2019 and 2018, respectively. Total unrecognized compensation expense relating to outstanding and unvested director RSUs was $0.2 million, which will be recognized over the remainder of the vesting period.

STATUTORY INFORMATION AND DIVID

STATUTORY INFORMATION AND DIVIDEND RESTRICTIONS	12 Months Ended
	Dec. 31, 2019
STATUTORY INFORMATION AND DIVIDEND RESTRICTIONS
STATUTORY INFORMATION AND DIVIDEND RESTRICTIONS	9.   STATUTORY INFORMATION AND DIVIDEND RESTRICTIONS ​ The statutory financial statements of our three insurance companies are presented on the basis of accounting practices prescribed or permitted by the Illinois Department of Insurance (IDOI), which has adopted the NAIC statutory accounting principles as the basis of its statutory accounting principles. We do not use any permitted statutory accounting principles that differ from NAIC prescribed statutory accounting principles. In converting from statutory to GAAP, typical adjustments include deferral of policy acquisition costs, the inclusion of statutory non-admitted assets and the inclusion of net unrealized holding gains or losses in shareholders’ equity relating to fixed income securities. ​ The NAIC has risk based capital (RBC) requirements for insurance companies to calculate and report information under a risk-based formula, which measures statutory capital and surplus needs based upon a regulatory definition of risk relative to the company’s balance sheet and mix of products. As of December 31, 2019, each of our insurance subsidiaries had an RBC amount in excess of the authorized control level RBC, as defined by the NAIC. RLI Insurance Company (RLI Ins.), our principal insurance company subsidiary, had an authorized control level RBC of $191.0 million, $170.9 million and $157.7 million as of December 31, 2019, 2018 and 2017, respectively, compared to actual statutory capital and surplus of $1,029.7 million, $829.8 million and $864.6 million, respectively, for these same periods. ​ Year-end statutory surplus for 2019 presented in the table below includes $190.9 million of RLI Corp. stock (cost basis of $64.6 million) held by Mt. Hawley Insurance Company, compared to $132.8 million and $106.9 million in 2018 and 2017, respectively. The Securities Valuation Office provides specific guidance for valuing this investment, which is eliminated in our GAAP consolidated financial statements. ​ The following table includes selected information for our insurance subsidiaries for the year ended and as of December 31: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Consolidated net income, statutory basis ​ $ 129,625 ​ $ 135,791 ​ $ 72,889 ​ Consolidated surplus, statutory basis ​ $ 1,029,671 ​ $ 829,775 ​ $ 864,554 ​ ​ As discussed in note 1.A., our three insurance companies are subsidiaries of RLI Corp., with RLI Ins. as the first-level, or principal, insurance subsidiary. At the holding company (RLI Corp.) level, we rely largely on dividends from our insurance company subsidiaries to meet our obligations for paying principal and interest on outstanding debt, corporate expenses and dividends to RLI Corp. shareholders. As discussed further below, dividend payments to RLI Corp. from our principal insurance subsidiary are restricted by state insurance laws as to the amount that may be paid without prior approval of the insurance regulatory authorities of Illinois. As a result, we may not be able to receive dividends from such subsidiary at times and in amounts necessary to pay desired dividends to RLI Corp. shareholders. On a GAAP basis, as of December 31, 2019, our holding company had $995.4 million in equity. This includes amounts related to the equity of our insurance subsidiaries, which is subject to regulatory restrictions under state insurance laws. The unrestricted portion of holding company net assets is comprised primarily of investments and cash, including $45.9 million in liquid assets . Unrestricted funds at the holding company are available to fund debt interest, general corporate obligations and regular dividend payments to our shareholders. If necessary, the holding company also has other potential sources of liquidity that could provide for additional funding to meet corporate obligations or pay shareholder dividends, which include a revolving line of credit, as well as access to capital markets. ​ Ordinary dividends, which may be paid by our principal insurance subsidiary without prior regulatory approval, are subject to certain limitations based upon statutory income, surplus and earned surplus. The maximum ordinary dividend distribution from our principal insurance subsidiary in a rolling 12-month period is limited by Illinois law to the greater of 10 percent of RLI Ins. policyholder surplus, as of December 31 of the preceding year, or the net income of RLI Ins. for the 12-month period ending December 31 of the preceding year. Ordinary dividends are further restricted by the requirement that they be paid from earned surplus. In 2019, 2018 and 2017, our principal insurance subsidiary paid ordinary dividends totaling $59.0 million, $13.0 million and $107.0 million, respectively, to RLI Corp. Any dividend distribution in excess of the ordinary dividend limits is deemed extraordinary and requires prior approval from the IDOI. In 2018, our principal insurance subsidiary sought and received regulatory approval prior to the payment of extraordinary dividends totaling $110.0 million. No extraordinary dividends were paid in 2019 or 2017. As of December 31, 2019, $65.3 million of the net assets of our principal insurance subsidiary are not restricted and could be distributed to RLI Corp. as ordinary dividends. Because the limitations are based upon a rolling 12-month period, the amount and impact of these restrictions vary over time. In addition to restrictions from our principal subsidiary’s insurance regulator, we also consider internal models and how capital adequacy is defined by our rating agencies in determining amounts available for distribution.

COMMITMENTS AND CONTINGENT LIAB

COMMITMENTS AND CONTINGENT LIABILITIES	12 Months Ended
	Dec. 31, 2019
COMMITMENTS AND CONTINGENT LIABILITIES
COMMITMENTS AND CONTINGENT LIABILITIES	10.   COMMITMENTS AND CONTINGENT LIABILITIES ​ LITIGATION ​ We are party to numerous claims, losses and litigation matters that arise in the normal course of our business. Many of such claims, losses or litigation matters involve claims under policies that we underwrite as an insurer. We believe that the resolution of these claims and losses will not have a material adverse effect on our financial condition, results of operations or cash flows. We are also involved in various other legal proceedings and litigation unrelated to our insurance business that arise in the ordinary course of business operations. Management believes that any liabilities that may arise as a result of these legal matters is not reasonably likely to have a material adverse effect on our financial condition, results of operations or cash flows. ​ COMMITMENTS ​ As of December 31, 2019, we had $15.5 million of unfunded commitments related to our investments in private funds and $8.6 million of unfunded commitments related to our low income housing tax credit investments. See note 2 for more information on these investments.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2019
Leases
LEASES	11. LEASES ​ We adopted ASU 2016-02, Leases on January 1, 2019, which resulted in the recognition of operating leases on the balance sheet in 2019 and forward. See note 1.C. for more information on the adoption of the ASU. Right-of-use assets are included in the other assets line item and lease liabilities are included in the other liabilities line item of the consolidated balance sheet. We determine if a contract contains a lease at inception and recognize operating lease right-of-use assets and operating lease liabilities based on the present value of the future minimum lease payments at the commencement date. Collateralized advance rates from an existing borrowing facility are obtained at the commencement date of each lease and serve as our incremental borrowing rate to determine the present value of future payments. Lease agreements may include options to extend or terminate. The options are exercised at our discretion and are included in operating lease liabilities if it is reasonably certain the option will be exercised. Lease agreements have lease and non-lease components, which are accounted for as a single lease component. Lease expense is recognized on a straight-line basis over the lease term. ​ The Company’s operating lease obligations are for branch office facilities. Our leases have remaining terms of one to 15 years . Expenses associated with leases totaled $6.9 million in 2018 and $6.8 million in 2017. The components of lease expense and other lease information as of and during the year ended December 31, 2019 are as follows: ​ ​ ​ ​ ​ ​ (in thousands) ​ 2019 Operating lease cost ​ $ 5,772 ​ ​ ​ ​ ​ ​ Cash paid for amounts included in measurement of lease liabilities ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 5,711 ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for new operating lease liabilities ​ $ 1,388 ​ ​ ​ ​ ​ ​ Reduction to right-of-use assets resulting from reduction to lease liabilities ​ $ 1,279 ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2019 Operating lease right-of-use assets ​ $ 22,335 ​ ​ ​ ​ ​ ​ Operating lease liabilities ​ $ 24,475 ​ ​ ​ ​ ​ ​ Weighted-average remaining lease term - operating leases ​ ​ 4.69 years ​ ​ ​ ​ ​ Weighted-average discount rate - operating leases ​ ​ 2.33 % ​ Future minimum lease payments under non-cancellable leases as of December 31, 2019 and 2018 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2019 ​ (in thousands) ​ 2018 2020 ​ $ 5,983 ​ 2019 ​ $ 5,911 2021 ​ ​ 5,968 ​ 2020 ​ ​ 6,019 2022 ​ ​ 5,904 ​ 2021 ​ ​ 5,924 2023 ​ ​ 4,386 ​ 2022 ​ ​ 5,884 2024 ​ ​ 2,334 ​ 2023 ​ ​ 4,459 Thereafter ​ ​ 1,366 ​ Thereafter ​ ​ 3,968 Total future minimum lease payments ​ $ 25,941 ​ Total future minimum lease payments ​ $ 32,165 Less imputed interest ​ ​ (1,466) ​ ​ ​ ​ ​ Total operating lease liability ​ $ 24,475 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

OPERATING SEGMENT INFORMATION

OPERATING SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2019
OPERATING SEGMENT INFORMATION
OPERATING SEGMENT INFORMATION	12. OPERATING SEGMENT INFORMATION ​ The segments of our insurance operations include casualty, property and surety. The casualty portion of our business consists largely of commercial excess, personal umbrella, general liability, transportation and executive products coverages, as well as package business and other specialty coverages, such as professional liability and workers’ compensation for office-based professionals. We also assume a limited amount of hard-to-place risks through a quota share reinsurance agreement. We provided medical and healthcare professional liability coverage in the excess and surplus market, but exited these businesses on a runoff basis in 2019. The casualty business is subject to the risk of estimating losses and related loss reserves because the ultimate settlement of a casualty claim may take several years to fully develop. The casualty segment is also subject to inflation risk and may be affected by evolving legislation and court decisions that define the extent of coverage and the amount of compensation due for injuries or losses. ​ Our property segment is comprised primarily of commercial fire, earthquake, difference in conditions and marine coverages. We also offer select personal lines policies, including homeowners’ coverages. Property insurance results are subject to the variability introduced by perils such as earthquakes, fires and hurricanes. Our major catastrophe exposure is to losses caused by earthquakes, primarily on the West Coast. Our second largest catastrophe exposure is to losses caused by wind storms to commercial properties throughout the Gulf and East Coast, as well as to homes we insure in Hawaii. We limit our net aggregate exposure to a catastrophic event by minimizing the total policy limits written in a particular region, purchasing reinsurance and maintaining policy terms and conditions throughout market cycles. We also use computer-assisted modeling techniques to provide estimates that help the Company carefully manage the concentration of risks exposed to catastrophic events. ​ The surety segment specializes in writing small to large-sized commercial and contract surety coverages, including payment and performance bonds. We also offer miscellaneous bonds including license and permit, notary and court bonds. Often, our surety coverages involve a statutory requirement for bonds. While these bonds typically maintain a relatively low loss ratio, losses may fluctuate due to adverse economic conditions affecting the financial viability of our insureds. The contract surety product guarantees the construction work of a commercial contractor for a specific project. Generally, losses occur due to the deterioration of a contractor’s financial condition. This line has historically produced marginally higher loss ratios than other surety lines during economic downturns. ​ Net investment income consists of the interest and dividend income streams from our investments in fixed income and equity securities. Interest and general corporate expenses include the cost of debt, other director and shareholder relations costs and other compensation-related expenses incurred for the benefit of the corporation, but not attributable to the operations of our insurance segments. Investee earnings represent our share in Maui Jim and Prime earnings. We own 40 percent of Maui Jim, a privately-held company which operates in the sunglass and optical goods industries, and 23 percent of Prime Holdings Insurance Services, Inc., a privately-held insurance company which specializes in hard-to-place risks. Our investment in Maui Jim, which is carried at the holding company, is unrelated to our core insurance operations. ​ The following table summarizes our segment data based on the internal structure and reporting of information as it is used by management. The net earnings of each segment are before taxes and include revenues (if applicable), direct product or segment costs (such as commissions and claims costs), as well as allocated support costs from various support departments. While depreciation and amortization charges have been included in these measures via our expense allocation system, the related assets are not allocated for management use and, therefore, are not included in this schedule. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ REVENUES ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Casualty ​ $ 558,458 ​ $ 523,472 ​ $ 478,603 ​ Property ​ 164,022 ​ 149,261 ​ 138,346 ​ Surety ​ 116,631 ​ 118,633 ​ 120,988 ​ Net premiums earned ​ $ 839,111 ​ $ 791,366 ​ $ 737,937 ​ Net investment income ​ 68,870 ​ 62,085 ​ 54,876 ​ Net realized gains ​ 17,520 ​ 63,407 ​ 4,411 ​ Net unrealized gains (losses) on equity securities ​ ​ 78,090 ​ ​ (98,735) ​ ​ — ​ Total ​ $ 1,003,591 ​ $ 818,123 ​ $ 797,224 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ INSURANCE EXPENSES ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Loss and settlement expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty ​ $ 330,156 ​ $ 329,763 ​ $ 305,679 ​ Property ​ 73,614 ​ 83,822 ​ 85,027 ​ Surety ​ 9,646 ​ 14,608 ​ 10,878 ​ Total loss and settlement expenses ​ $ 413,416 ​ $ 428,193 ​ $ 401,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Policy acquisition costs: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty ​ $ 166,499 ​ $ 151,007 ​ $ 136,135 ​ Property ​ 55,986 ​ 51,830 ​ 51,070 ​ Surety ​ 66,212 ​ 64,901 ​ 65,310 ​ Total policy acquisition costs ​ $ 288,697 ​ $ 267,738 ​ $ 252,515 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other insurance expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty ​ $ 41,202 ​ $ 31,562 ​ $ 32,885 ​ Property ​ 16,279 ​ 12,725 ​ 14,108 ​ Surety ​ 11,949 ​ 9,516 ​ 10,001 ​ Total other insurance expenses ​ $ 69,430 ​ $ 53,803 ​ $ 56,994 ​ Total ​ $ 771,543 ​ $ 749,734 ​ $ 711,093 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NET EARNINGS (LOSSES) ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Casualty ​ $ 20,601 ​ $ 11,140 ​ $ 3,904 ​ Property ​ 18,143 ​ 884 ​ (11,859) ​ Surety ​ 28,824 ​ 29,608 ​ 34,799 ​ Net underwriting income ​ $ 67,568 ​ $ 41,632 ​ $ 26,844 ​ Net investment income ​ 68,870 ​ 62,085 ​ 54,876 ​ Net realized gains ​ 17,520 ​ 63,407 ​ 4,411 ​ Net unrealized gains (losses) on equity securities ​ ​ 78,090 ​ ​ (98,735) ​ ​ — ​ General corporate expense and interest on debt ​ (20,274) ​ (16,864) ​ (18,766) ​ Equity in earnings of unconsolidated investees ​ 20,960 ​ 16,056 ​ 17,224 ​ Total earnings before incomes taxes ​ $ 232,734 ​ $ 67,581 ​ $ 84,589 ​ Income tax expense (benefit) ​ $ 41,092 ​ $ 3,402 ​ $ (20,439) ​ Total ​ $ 191,642 ​ $ 64,179 ​ $ 105,028 ​ ​ The following table further summarizes revenues by major product type within each segment: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NET PREMIUMS EARNED ​ Year ended December 31, (in thousands) 2019 2018 2017 CASUALTY ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial excess and personal umbrella ​ $ 140,483 ​ $ 124,350 ​ $ 115,543 ​ General liability ​ 98,880 ​ 93,928 ​ 90,283 ​ Commercial transportation ​ 83,213 ​ 81,053 ​ 78,061 ​ Professional services ​ 81,329 ​ 79,951 ​ 78,508 ​ Small commercial ​ 55,701 ​ 51,519 ​ 49,601 ​ Executive products ​ 27,088 ​ 21,326 ​ 18,086 ​ Other casualty ​ 71,764 ​ 71,345 ​ 48,521 ​ Total ​ $ 558,458 ​ $ 523,472 ​ $ 478,603 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ PROPERTY ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Marine ​ $ 74,887 ​ $ 59,795 ​ $ 50,931 ​ Commercial property ​ ​ 68,310 ​ ​ 71,501 ​ ​ 63,117 ​ Specialty personal ​ ​ 19,316 ​ ​ 16,901 ​ ​ 20,793 ​ Other property ​ 1,509 ​ 1,064 ​ 3,505 ​ Total ​ $ 164,022 ​ $ 149,261 ​ $ 138,346 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SURETY ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Miscellaneous ​ $ 44,721 ​ $ 46,968 ​ $ 47,237 ​ Commercial ​ 43,553 ​ 43,469 ​ 45,178 ​ Contract ​ 28,357 ​ 28,196 ​ 28,573 ​ Total ​ $ 116,631 ​ $ 118,633 ​ $ 120,988 ​ Grand total ​ $ 839,111 ​ $ 791,366 ​ $ 737,937 ​ ​

UNAUDITED INTERIM FINANCIAL INF

UNAUDITED INTERIM FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2019
UNAUDITED INTERIM FINANCIAL INFORMATION
UNAUDITED INTERIM FINANCIAL INFORMATION	13. UNAUDITED INTERIM FINANCIAL INFORMATION ​ Select unaudited quarterly information is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands, except per share data) First Second Third Fourth Year ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net premiums earned ​ $ 204,689 ​ $ 207,541 ​ $ 211,255 ​ $ 215,626 ​ $ 839,111 ​ Net investment income ​ 16,565 ​ 16,998 ​ 17,532 ​ 17,775 ​ 68,870 ​ Net realized gains ​ 9,068 ​ 4,764 ​ 3,211 ​ 477 ​ 17,520 ​ Net unrealized gains (losses) on equity securities ​ ​ 33,498 ​ ​ 8,810 ​ ​ 4,906 ​ ​ 30,876 ​ ​ 78,090 ​ Earnings (losses) before income taxes ​ 81,741 ​ 48,828 ​ 38,947 ​ 63,218 ​ 232,734 ​ Net earnings (loss) ​ 65,473 ​ 40,467 ​ 32,324 ​ 53,378 ​ 191,642 ​ Basic earnings per share(1) ​ $ 1.47 ​ $ 0.91 ​ $ 0.72 ​ $ 1.19 ​ $ 4.28 ​ Diluted earnings per share(1) ​ $ 1.46 ​ $ 0.89 ​ $ 0.71 ​ $ 1.18 ​ $ 4.23 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net premiums earned ​ $ 190,027 ​ $ 196,522 ​ $ 200,815 ​ $ 204,002 ​ $ 791,366 ​ Net investment income ​ 14,232 ​ 14,577 ​ 16,314 ​ 16,962 ​ 62,085 ​ Net realized gains ​ 8,404 ​ 20,849 ​ 18,647 ​ 15,507 ​ 63,407 ​ Net unrealized gains (losses) on equity securities ​ ​ (26,772) ​ ​ (12,611) ​ ​ 4,848 ​ ​ (64,200) ​ ​ (98,735) ​ Earnings (losses) before income taxes ​ 14,378 ​ 39,562 ​ 46,349 ​ (32,708) ​ 67,581 ​ Net earnings (loss) ​ 12,216 ​ 33,251 ​ 39,372 ​ (20,660) ​ 64,179 ​ Basic earnings per share(1) ​ $ 0.28 ​ $ 0.75 ​ $ 0.89 ​ $ (0.46) ​ $ 1.45 ​ Diluted earnings per share(1) ​ $ 0.27 ​ $ 0.74 ​ $ 0.88 ​ $ (0.46) ​ $ 1.43 ​ (1) Since the weighted-average shares for the quarters are calculated independently of the weighted-average shares for the year, quarterly earnings per share may not total to annual earnings per share.

SCHEDULE I-SUMMARY OF INVESTMEN

SCHEDULE I-SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES	12 Months Ended
	Dec. 31, 2019
SCHEDULE I-SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
SCHEDULE I-SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES	RLI CORP. AND SUBSIDIARIES ​ SCHEDULE I—SUMMARY OF INVESTMENTS—OTHER THAN INVESTMENTS IN RELATED PARTIES ​ December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Column A Column B Column C Column D ​ ​ ​ ​ ​ ​ ​ ​ Amount at (in thousands) ​ ​ ​ ​ ​ ​ ​ which shown in Type of Investment ​ Cost (1) ​ Fair Value ​ the balance sheet Fixed maturities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Bonds: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ 186,699 ​ $ 193,661 ​ $ 193,661 ​ U.S. agency ​ 36,535 ​ 38,855 ​ 38,855 ​ Non-U.S. government & agency ​ 7,333 ​ 7,628 ​ 7,628 ​ Agency MBS ​ 411,808 ​ ​ 420,165 ​ ​ 420,165 ​ ABS/CMBS/MBS* ​ ​ 222,832 ​ 224,870 ​ 224,870 ​ Corporate ​ 659,640 ​ 692,067 ​ 692,067 ​ Municipal ​ 390,431 ​ 405,840 ​ 405,840 ​ Total available-for-sale ​ $ 1,915,278 ​ $ 1,983,086 ​ $ 1,983,086 ​ Total fixed maturities ​ $ 1,915,278 ​ $ 1,983,086 ​ $ 1,983,086 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Common stock: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ind Misc and all other ​ $ 139,588 ​ $ 250,831 ​ $ 250,831 ​ ETFs (Ind/misc) ​ 122,543 ​ 209,799 ​ 209,799 ​ Total equity securities ​ $ 262,131 ​ $ 460,630 ​ $ 460,630 ​ Cash and short-term investments ​ ​ 46,203 ​ ​ 46,203 ​ ​ 46,203 ​ Other invested assets ​ ​ 70,725 ​ ​ 70,441 ​ ​ 70,441 ​ Total investments and cash ​ $ 2,294,337 ​ $ 2,560,360 ​ $ 2,560,360 ​ * ​ Note: See notes 1E and 2 of Notes to Consolidated Financial Statements. See also the accompanying report of independent registered public accounting firm on page 101 of this report. ​ (1) Original cost of equity securities and, as to fixed maturities, original cost reduced by repayments and adjusted for amortization of premiums or accrual of discounts.

SCHEDULE II-CONDENSED FINANCIAL

SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY)	12 Months Ended
	Dec. 31, 2019
SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY)
SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY)	RLI CORP. AND SUBSIDIARIES ​ SCHEDULE II—CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) CONDENSED BALANCE SHEETS ​ December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands, except share data) 2019 2018 Assets ​ ​ ​ ​ ​ ​ ​ Cash ​ $ 350 ​ $ 3,214 ​ Investments in subsidiaries ​ 1,034,679 ​ 828,806 ​ Investments in unconsolidated investee ​ 79,597 ​ 79,521 ​ Fixed income: ​ ​ ​ ​ ​ ​ ​ Available-for-sale, at fair value (amortized cost - $42,747 in 2019 and $58,812 in 2018) ​ 45,538 ​ 59,878 ​ Property and equipment, at cost, net of accumulated depreciation of $1,562 in 2019 and $1,494 in 2018 ​ 1,846 ​ 1,914 ​ Income taxes receivable - current ​ 842 ​ — ​ Other assets ​ 400 ​ 547 ​ Total assets ​ $ 1,163,252 ​ $ 973,880 ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities and Shareholders' Equity ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ Accounts payable, affiliates ​ $ 1,310 ​ $ 130 ​ Income taxes payable - current ​ ​ — ​ ​ 32 ​ Income taxes - deferred ​ ​ 14,578 ​ ​ 15,081 ​ Bonds payable, long-term debt ​ 149,302 ​ 149,115 ​ Interest payable, long-term debt ​ 2,153 ​ 2,153 ​ Other liabilities ​ 521 ​ 527 ​ Total liabilities ​ $ 167,864 ​ $ 167,038 ​ ​ ​ ​ ​ ​ ​ ​ ​ Shareholders’ equity: ​ ​ ​ ​ ​ ​ ​ Common stock ($0.01 par value 100,000,000 share authorized) ​ ​ ​ ​ ​ ​ ​ (67,799,229 shares issued and 44,869,015 shares outstanding in 2019) ​ ​ ​ ​ ​ ​ ​ (67,434,257 shares issued and 44,504,043 shares outstanding in 2018) ​ $ 678 ​ $ 674 ​ Paid-in capital ​ 321,190 ​ 305,660 ​ Accumulated other comprehensive earnings, net of tax ​ 52,473 ​ (14,572) ​ Retained earnings ​ 1,014,046 ​ 908,079 ​ Deferred compensation ​ 7,980 ​ 8,354 ​ Treasury stock, at cost (22,930,214 shares in 2019 and 2018) ​ (400,979) ​ (401,353) ​ Total shareholders’ equity ​ $ 995,388 ​ $ 806,842 ​ Total liabilities and shareholders’ equity ​ $ 1,163,252 ​ $ 973,880 ​ ​ See Notes to Consolidated Financial Statements. See also the accompanying report of independent registered public accounting firm on page 101 of this report. ​ ​ RLI CORP. AND SUBSIDIARIES ​ SCHEDULE II—CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY)—(continued) CONDENSED STATEMENTS OF EARNINGS AND COMPREHENSIVE EARNINGS ​ Years ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Net investment income ​ $ 1,656 ​ $ 648 ​ $ 647 ​ Net realized gains (losses) ​ 463 ​ (142) ​ (36) ​ Equity in earnings of unconsolidated investee ​ 13,592 ​ 12,471 ​ 14,436 ​ Selling, general and administrative expenses ​ (12,686) ​ (9,427) ​ (11,340) ​ Interest expense on debt ​ (7,588) ​ (7,437) ​ (7,426) ​ Loss before income taxes ​ $ (4,563) ​ $ (3,887) ​ $ (3,719) ​ Income tax benefit ​ (4,989) ​ (2,359) ​ (16,601) ​ Net earnings (loss) before equity in net earnings of subsidiaries ​ $ 426 ​ $ (1,528) ​ $ 12,882 ​ Equity in net earnings of subsidiaries ​ 191,216 ​ 65,707 ​ 92,146 ​ Net earnings ​ $ 191,642 ​ $ 64,179 ​ $ 105,028 ​ Other comprehensive earnings (loss), net of tax ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized gains (losses) on securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized holding gains arising during the period ​ $ 1,727 ​ $ 710 ​ $ 21 ​ Less: reclassification adjustment for (gains) losses included in net earnings ​ (365) ​ 112 ​ 6 ​ Other comprehensive earnings - parent only ​ $ 1,362 ​ $ 822 ​ $ 27 ​ Equity in other comprehensive earnings (loss) of subsidiaries/investees ​ 65,683 ​ (34,819) ​ 35,282 ​ Other comprehensive earnings (loss) ​ $ 67,045 ​ $ (33,997) ​ $ 35,309 ​ Comprehensive earnings ​ $ 258,687 ​ $ 30,182 ​ $ 140,337 ​ ​ See Notes to Consolidated Financial Statements. See also the accompanying report of independent registered public accounting firm on page 101 of this report. ​ ​ RLI CORP. AND SUBSIDIARIES ​ SCHEDULE II—CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY)—(continued) CONDENSED STATEMENTS OF CASH FLOWS ​ Years ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Cash flows from operating activities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings (loss) before equity in net earnings of subsidiaries ​ $ 426 ​ $ (1,528) ​ $ 12,882 ​ Adjustments to reconcile net losses to net cash provided by (used in) operating activities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized (gains) losses ​ (463) ​ 142 ​ 36 ​ Depreciation ​ 68 ​ 68 ​ 77 ​ Other items, net ​ 2,487 ​ (471) ​ 595 ​ Change in: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Affiliate balances receivable/payable ​ 1,180 ​ 1,187 ​ (930) ​ Federal income taxes ​ (1,673) ​ 3,430 ​ (6,874) ​ Changes in investment in unconsolidated investee: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Undistributed earnings ​ (13,592) ​ (12,471) ​ (14,436) ​ Dividends received ​ 13,200 ​ 9,900 ​ — ​ Net cash provided by (used in) operating activities ​ $ 1,633 ​ $ 257 ​ $ (8,650) ​ Cash flows from investing activities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Purchase of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed income, available-for-sale ​ $ (2,507) ​ $ (73,812) ​ $ (5,773) ​ Sale of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed income, available-for-sale ​ 14,273 ​ 12,056 ​ 24,771 ​ Property and equipment ​ — ​ — ​ 128 ​ Call or maturity of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed income, available-for-sale ​ 29,501 ​ 75,662 ​ 3,499 ​ Net proceeds from sale (purchase) of short-term investments ​ ​ — ​ ​ 70 ​ ​ (47) ​ Cash dividends received-subsidiaries ​ 34,003 ​ 73,363 ​ 107,000 ​ Net cash provided by investing activities ​ $ 75,270 ​ $ 87,339 ​ $ 129,578 ​ Cash flows from financing activities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Proceeds from stock option exercises ​ $ 9,490 ​ $ 6,076 ​ $ 3,502 ​ Cash dividends paid ​ (93,315) ​ (90,662) ​ (124,247) ​ Other ​ ​ 4,058 ​ ​ — ​ ​ — ​ Net cash used in financing activities ​ $ (79,767) ​ $ (84,586) ​ $ (120,745) ​ Net increase (decrease) in cash ​ $ (2,864) ​ $ 3,010 ​ $ 183 ​ Cash at beginning of year ​ 3,214 ​ 204 ​ 21 ​ Cash at end of year ​ $ 350 ​ $ 3,214 ​ $ 204 ​ ​ Interest paid on outstanding debt amounted to $7.3 million for 2019, 2018 and 2017, respectively. See Notes to Consolidated Financial Statements. See also the accompanying report of independent registered public accounting firm on page 101 of this report.

SCHEDULE III-SUPPLEMENTARY INSU

SCHEDULE III-SUPPLEMENTARY INSURANCE INFORMATION	12 Months Ended
	Dec. 31, 2019
SCHEDULE III-SUPPLEMENTARY INSURANCE INFORMATION
SCHEDULE III-SUPPLEMENTARY INSURANCE INFORMATION	RLI CORP. AND SUBSIDIARIES ​ SCHEDULE III—SUPPLEMENTARY INSURANCE INFORMATION ​ As of and for the years ended December 31, 2019, 2018 and 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred losses ​ ​ Deferred policy ​ Unpaid losses ​ Unearned ​ Net ​ and settlement ​ ​ acquisition ​ and settlement ​ premiums, ​ premiums ​ expenses (in thousands) ​ costs ​ expenses, gross ​ gross ​ earned ​ current year Year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ 47,805 ​ $ 1,435,619 ​ $ 354,118 ​ $ 558,458 ​ $ 392,653 ​ Property segment ​ 17,057 ​ 100,000 ​ 116,624 ​ 164,022 ​ 78,075 ​ Surety segment ​ 20,182 ​ 38,733 ​ 69,471 ​ 116,631 ​ 17,972 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group ​ $ 85,044 ​ $ 1,574,352 ​ $ 540,213 ​ $ 839,111 ​ $ 488,700 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ 50,040 ​ $ 1,283,204 ​ $ 330,836 ​ $ 523,472 ​ $ 363,015 ​ Property segment ​ 14,090 ​ 134,822 ​ 93,032 ​ 149,261 ​ 94,635 ​ Surety segment ​ 20,804 ​ 43,322 ​ 72,637 ​ 118,633 ​ 20,493 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group ​ $ 84,934 ​ $ 1,461,348 ​ $ 496,505 ​ $ 791,366 ​ $ 478,143 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ 44,358 ​ $ 1,127,787 ​ $ 296,751 ​ $ 478,603 ​ $ 323,141 ​ Property segment ​ 13,029 ​ 107,304 ​ 84,010 ​ 138,346 ​ 97,161 ​ Surety segment ​ 20,329 ​ 36,412 ​ 70,688 ​ 120,988 ​ 20,150 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group ​ $ 77,716 ​ $ 1,271,503 ​ $ 451,449 ​ $ 737,937 ​ $ 440,452 ​ ​ NOTE 1: Investment income is not allocated to the segments, therefore, net investment income has not been provided. ​ See the accompanying report of independent registered public accounting firm on page 101 of this report. ​ ​ RLI CORP. AND SUBSIDIARIES ​ SCHEDULE III—SUPPLEMENTARY INSURANCE INFORMATION (continued) ​ As of and for the years ended December 31, 2019, 2018 and 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred ​ ​ ​ ​ ​ ​ ​ ​ losses and ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ settlement ​ Policy ​ Other ​ Net ​ ​ expenses ​ acquisition ​ operating ​ premiums (in thousands) ​ prior year ​ costs ​ expenses ​ written Year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ (62,497) ​ $ 166,499 ​ $ 41,202 ​ $ 564,979 ​ Property segment ​ (4,461) ​ 55,986 ​ 16,279 ​ 181,974 ​ Surety segment ​ (8,326) ​ 66,212 ​ 11,949 ​ 113,384 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group ​ $ (75,284) ​ $ 288,697 ​ $ 69,430 ​ $ 860,337 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ (33,252) ​ $ 151,007 ​ $ 31,562 ​ $ 547,177 ​ Property segment ​ (10,813) ​ 51,830 ​ 12,725 ​ 155,601 ​ Surety segment ​ (5,885) ​ 64,901 ​ 9,516 ​ 120,397 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group ​ $ (49,950) ​ $ 267,738 ​ $ 53,803 ​ $ 823,175 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ (17,462) ​ $ 136,135 ​ $ 32,885 ​ $ 494,649 ​ Property segment ​ (12,134) ​ 51,070 ​ 14,108 ​ 137,031 ​ Surety segment ​ (9,272) ​ 65,310 ​ 10,001 ​ 118,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group ​ $ (38,868) ​ $ 252,515 ​ $ 56,994 ​ $ 749,854 ​ ​ See the accompanying report of independent registered public accounting firm on page 101 of this report.

SCHEDULE IV-REINSURANCE

SCHEDULE IV-REINSURANCE	12 Months Ended
	Dec. 31, 2019
SCHEDULE IV-REINSURANCE
SCHEDULE IV-REINSURANCE	RLI CORP. AND SUBSIDIARIES ​ SCHEDULE IV—REINSURANCE ​ Years ended December 31, 2019, 2018 and 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Percentage ​ ​ ​ ​ ​ Ceded to ​ Assumed ​ ​ ​ ​ of amount ​ ​ Direct ​ other ​ from other ​ Net ​ assumed (in thousands) ​ amount ​ companies ​ companies ​ amount ​ to net 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ 641,159 ​ $ 122,452 ​ $ 39,751 ​ $ 558,458 7.1 % Property segment ​ 217,657 ​ 53,810 ​ 175 ​ 164,022 0.1 % Surety segment ​ 122,305 ​ 5,921 ​ 247 ​ 116,631 0.2 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group premiums earned ​ $ 981,121 ​ $ 182,183 ​ $ 40,173 ​ $ 839,111 4.8 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ 578,643 ​ $ 96,639 ​ $ 41,468 ​ $ 523,472 7.9 % Property segment ​ 193,855 ​ 44,634 ​ 40 ​ 149,261 0.0 % Surety segment ​ 123,736 ​ 5,521 ​ 418 ​ 118,633 0.4 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group premiums earned ​ $ 896,234 ​ $ 146,794 ​ $ 41,926 ​ $ 791,366 5.3 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty segment ​ $ 536,085 ​ $ 86,190 ​ $ 28,708 ​ $ 478,603 6.0 % Property segment ​ 172,668 ​ 37,607 ​ 3,285 ​ 138,346 2.4 % Surety segment ​ 126,365 ​ 5,905 ​ 528 ​ 120,988 0.4 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RLI Insurance Group premiums earned ​ $ 835,118 ​ $ 129,702 ​ $ 32,521 ​ $ 737,937 4.4 % ​ See the accompanying report of independent registered public accounting firm on page 101 of this report.

SCHEDULE V-VALUATION AND QUALIF

SCHEDULE V-VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2019
SCHEDULE V-VALUATION AND QUALIFYING ACCOUNTS
SCHEDULE V-VALUATION AND QUALIFYING ACCOUNTS	RLI CORP. AND SUBSIDIARIES ​ SCHEDULE V—VALUATION AND QUALIFYING ACCOUNTS ​ Years ended December 31, 2019, 2018 and 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance Amounts Amounts Balance ​ ​ at beginning ​ charged ​ recovered ​ at end of (in thousands) ​ of period ​ to expense ​ (written off) ​ period ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 Allowance for uncollectible reinsurance ​ $ 25,911 ​ $ (647) ​ $ (198) ​ $ 25,066 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2018 Allowance for uncollectible reinsurance ​ $ 25,911 ​ $ — ​ $ — ​ $ 25,911 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2017 Allowance for uncollectible reinsurance ​ $ 25,911 ​ $ — ​ $ — ​ $ 25,911 ​ ​ See the accompanying report of independent registered public accounting firm on page 101 of this report.

SCHEDULE VI-SUPPLEMENTARY INFOR

SCHEDULE VI-SUPPLEMENTARY INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS	12 Months Ended
	Dec. 31, 2019
SCHEDULE VI-SUPPLEMENTARY INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
SCHEDULE VI-SUPPLEMENTARY INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS	RLI CORP. AND SUBSIDIARIES ​ SCHEDULE VI—SUPPLEMENTARY INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS ​ Years ended December 31, 2019, 2018 and 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ Deferred policy ​ Claims and ​ Unearned ​ Net ​ Net Affiliation with ​ acquisition ​ claim adjustment ​ premiums, ​ premiums ​ investment Registrant (1) costs expense reserves gross earned income ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 ​ $ 85,044 ​ $ 1,574,352 ​ $ 540,213 ​ $ 839,111 ​ $ 68,870 ​ 2018 ​ $ 84,934 ​ $ 1,461,348 ​ $ 496,505 ​ $ 791,366 ​ $ 62,085 ​ 2017 ​ $ 77,716 ​ $ 1,271,503 ​ $ 451,449 ​ $ 737,937 ​ $ 54,876 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and claim adjustment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ expenses incurred related to: ​ Amortization ​ Paid claims and ​ Net ​ Current Prior of deferred claim adjustment premiums ​ ​ year ​ year ​ acquisition costs ​ expenses ​ written ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 ​ $ 488,700 ​ $ (75,284) ​ $ 288,697 ​ $ 319,930 ​ $ 860,337 ​ 2018 ​ $ 478,143 ​ $ (49,950) ​ $ 267,738 ​ $ 301,356 ​ $ 823,175 ​ 2017 ​ $ 440,452 ​ $ (38,868) ​ $ 252,515 ​ $ 283,185 ​ $ 749,854 ​ (1) Consolidated property-casualty insurance operations. ​ See the accompanying report of independent registered public accounting firm on page 101 of this report.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
DESCRIPTION OF BUSINESS	A. DESCRIPTION OF BUSINESS ​ RLI Corp. is an insurance holding company. References to “the Company,” “we,” “our,” “us” or like terms refer to the business of RLI Corp. and its subsidiaries. We underwrite select property and casualty insurance coverages through major subsidiaries collectively known as RLI Insurance Group. We conduct operations principally through three insurance companies. RLI Insurance Company (RLI Ins.), a subsidiary of RLI Corp. and our principal insurance subsidiary, writes multiple lines of insurance on an admitted basis in all 50 states, the District of Columbia, Puerto Rico, the Virgin Islands and Guam. Mt. Hawley Insurance Company (Mt. Hawley), a subsidiary of RLI Ins., writes excess and surplus lines insurance on a non-admitted basis in all 50 states, the District of Columbia, Puerto Rico, the Virgin Islands and Guam. Contractors Bonding and Insurance Company (CBIC), a subsidiary of RLI Ins., writes multiple lines of insurance on an admitted basis in all 50 states and the District of Columbia. ​ On May 4, 2018, RLI Corp. changed its state of incorporation from the State of Illinois to the State of Delaware (the Reincorporation). The Reincorporation was effected by merging RLI Corp., an Illinois corporation (RLI Illinois), into RLI Corp., a Delaware corporation (RLI Delaware). The separate corporate existence of RLI Illinois ceased and RLI Delaware continues in existence as the surviving corporation and possesses all rights, privileges, powers and franchises of RLI Illinois. The Reincorporation did not result in any change in the name, business, management, fiscal year, location of the principal executive offices, assets or liabilities of the Company. Each outstanding share of RLI Illinois common stock, which had a par value of $1.00 per share, was automatically converted into one outstanding share of RLI Delaware common stock, with a par value of $0.01 per share. In order to reflect the new par value of common stock on the balance sheet, a $66.4 million reclassification from common stock to paid -in-capital was made.
PRINCIPLES OF CONSOLIDATION AND BASIS OF PRESENTATION	B. PRINCIPLES OF CONSOLIDATION AND BASIS OF PRESENTATION ​ The accompanying consolidated financial statements were prepared in conformity with generally accepted accounting principles in the United States of America (GAAP), which differ in some respects from those followed in reports to insurance regulatory authorities. The consolidated financial statements include the accounts of our holding company and our subsidiaries. Intercompany balances and transactions have been eliminated. Certain reclassifications were made to 2018 and 2017 to conform to the classifications used in the current year. The Company has evaluated subsequent events through the date these consolidated financial statements were issued. There were no subsequent events requiring adjustment to the financial statements or disclosure.
ADOPTED ACCOUNTING STANDARDS	C. ADOPTED ACCOUNTING STANDARDS ​ ASU 2016-02, Leases (Topic 842) ​ ASU 2016-02 was issued to improve the financial reporting of leasing transactions. Under previous guidance for lessees, leases were only included on the balance sheet if certain criteria, classifying the agreement as a capital lease, were met. This update requires the recognition of a right-of-use asset and a corresponding lease liability, discounted to the present value, for all leases that extend beyond 12 months. For operating leases, the asset and liability are expensed over the lease term on a straight-line basis, with all cash flows included in the operating section of the statement of cash flows. For finance leases, interest on the lease liability is recognized separately from the amortization of the right-of-use asset in the statement of earnings and the repayment of the principal portion of the lease liability is classified as a financing activity while the interest component is included in the operating section of the statement of cash flows. ​ We adopted ASU 2016-02, ASU 2018-10 Codification Improvements to Topic 842: Leases and ASU 2018-11 Leases (Topic 842): Targeted Improvements on January 1, 2019. We applied the standards using the alternative transition method provided by ASU 2018-11 under which leases were recognized at the date of adoption and a cumulative-effect adjustment to the opening balance of retained earnings would have been recognized in the period of adoption. As the standard did not have an impact on our net earnings, no adjustment to the opening balance of retained earnings was required. As of December 31, 2019, $22.3 million of right-of-use assets and $24.5 million of lease liabilities were included in the other assets and other liabilities line items of the consolidated balance sheet, respectively, as a result of the adoption of these updates. We implemented controls for the adoption of the standard and the ongoing monitoring of the right-of-use asset and lease liability, but they did not materially affect our internal control over financial reporting. ASU 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities ​ Under previous guidance, the amortization period for callable debt securities held at a premium was generally the contractual life of the instrument. However, if an entity had a large number of similar loans, it could consider estimates of future principal prepayments. For those who chose not to incorporate an estimate of future prepayments, ASU 2017-08 shortens the amortization period for premium on debt securities to the earliest call date, rather than the maturity date, to align the amortization method with how the securities are quoted, priced and traded. After the earliest call date, if the call option is not exercised, the entity shall reset the effective yield using the payment terms of the debt security. Any excess of the amortized cost basis over the amount payable will be amortized to the next call date or to maturity if there are no other call dates. The method of accounting for a discount does not change and will continue to be amortized over the life of the bond. ​ We adopted ASU 2017-08 on January 1, 2019 using a modified-retrospective approach. As we had been incorporating estimates of future principal prepayments when calculating the effective yield for bonds carrying a premium under the old guidance, the adoption of this update did not have a material impact on our financial statements. ​ ASU 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ​ ASU 2018-07 was issued to simplify the accounting for share-based transactions by expanding the scope of Topic 718 from only being applicable to share-based payments to employees to include share-based payment transactions for acquiring goods and services from nonemployees. As a result, nonemployee share-based transactions will be measured by estimating the fair value of the equity instruments at the grant date, taking into consideration the probability of satisfying performance conditions. We adopted ASU 2018-07 on January 1, 2019. Our long-term incentive plan limits the awards of share-based payments to employees and directors of the Company. As our share-based compensation expense to nonemployee directors was $0.6 million in 2019, the standard did not have a material impact on our financial statements.
PROSPECTIVE ACCOUNTING STANDARDS	D. PROSPECTIVE ACCOUNTING STANDARDS ​ ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) ​ ASU 2016-13 was issued to provide more decision-useful information about the expected credit losses on financial instruments. Current GAAP delays the recognition of credit losses until it is probable a loss has been incurred. The update will require a financial asset measured at amortized cost, including reinsurance balances recoverable, to be presented at the net amount expected to be collected by means of an allowance for credit losses that runs through net earnings. Credit losses relating to available-for-sale debt securities will also be recorded through an allowance for credit losses. However, the amendments would limit the amount of the allowance to the amount by which fair value is below amortized cost. The measurement of credit losses on available-for-sale securities is similar under current GAAP, but the update requires the use of the allowance account through which amounts can be reversed, rather than through an irreversible write-down. ​ This ASU is effective for annual and interim reporting periods beginning after December 15, 2019. Early adoption is permitted beginning after December 15, 2018. Upon adoption, the update will be applied using the modified-retrospective approach, by which a cumulative-effect adjustment will be made to retained earnings as of the beginning of the first reporting period in which the guidance is effective. This update will have the most impact on our available-for-sale fixed income portfolio and reinsurance balances recoverable. However, as our fixed income portfolio is weighted towards higher rated bonds (85 percent rated A or better at December 31, 2019) and we purchase reinsurance from financially strong reinsurers for which we already have an allowance for uncollectible reinsurance amounts, the effect of adoption will not have a material impact on our financial statements. ​ ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement ​ ASU 2018-13 modifies the disclosure requirements for assets and liabilities measured at fair value. The requirements to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, the policy for timing of transfers between levels and the valuation processes for Level 3 fair value measurements have all been removed. However, the changes in unrealized gains and losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period must be disclosed along with the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements (or other quantitative information if it is more reasonable). Finally, for investments measured at net asset value, the requirements have been modified so that the timing of liquidation and the date when restrictions from redemption might lapse are only disclosed if the investee has communicated the timing to the entity or announced the timing publicly. ​ This ASU is effective for annual and interim reporting periods beginning after December 15, 2019. As the amendments are only disclosure related, the effect of adoption will not have a material impact on our financial statements.
INVESTMENTS	E. INVESTMENTS ​ Equity securities are carried at fair value with unrealized gains and losses recorded within net earnings in 2019 and 2018. Prior to 2018, unrealized gains and losses on equity securities were recognized through other comprehensive earnings. Investments in fixed income securities are classified into one of three categories: trading, held-to-maturity or available-for-sale. All of our fixed income securities are classified as available-for-sale and reported at fair value. Unrealized gains and losses on these securities are excluded from net earnings but are recorded as a separate component of comprehensive earnings and shareholders’ equity, net of deferred income taxes. ​ Other-than-Temporary Impairment ​ We regularly evaluate our fixed income securities using quantitative and qualitative criteria to determine impairment losses for other-than-temporary declines in the fair value of the investments. The following are the key factors for determining if a security is other-than-temporarily impaired: ​ ● The length of time and the extent to which the fair value has been less than amortized cost, ​ ● The probability of significant adverse changes to the cash flows, ​ ● The occurrence of a discrete credit event resulting in the issuer defaulting on a material obligation, the issuer seeking protection from creditors under the bankruptcy laws, the issuer proposing a voluntary reorganization under which creditors are asked to exchange their claims for cash or securities having a fair value substantially lower than par value of their claims or ​ ● The probability that we will recover the entire amortized cost basis of our fixed income securities prior to maturity. ​ Quantitative criteria considered during this process include, but are not limited to: the degree and duration of current fair value as compared to the amortized cost of the security, degree and duration of the security’s fair value being below cost and whether the issuer is in compliance with terms and covenants of the security. Qualitative criteria include the credit quality, current economic conditions, the anticipated speed of cost recovery, the financial health of and specific prospects for the issuer, as well as our absence of intent to sell or requirement to sell fixed income securities prior to recovery. In addition, we consider price declines in our other-than-temporary impairment (OTTI) analysis when they provide evidence of declining credit quality, and we distinguish between price changes caused by credit deterioration, as opposed to rising interest rates. See note 2 for further discussion of OTTI. ​ Interest on fixed maturities and short-term investments is credited to earnings on an accrual basis. Premiums and discounts are amortized or accreted over the lives of the related fixed maturities. Dividends on equity securities are credited to earnings on the ex-dividend date. Realized gains and losses on disposition of investments are based on specific identification of the investments sold on the settlement date.
CASH AND SHORT-TERM INVESTMENTS	F. CASH, SHORT-TERM INVESTMENTS AND OTHER INVESTED ASSETS ​ Cash consists of uninvested balances in bank accounts. Short-term investments consist of investments with original maturities of 90 days or less, primarily AAA-rated prime and government money market funds. Short-term investments are carried at cost. We have not experienced losses on these instruments. Other invested assets include investments in low income housing tax credit partnerships (LIHTC), membership in the Federal Home Loan Bank of Chicago (FHLBC) and investments in private funds. Our LIHTC investments are carried at amortized cost, and our investment in FHLBC stock is carried at cost. Due to the nature of cash, short-term investments, the LIHTC and our membership in the FHLBC, their carrying amounts approximate fair value. The private funds are carried at fair value, using each investment’s net asset value.
REINSURANCE	G. REINSURANCE ​ Ceded unearned premiums and reinsurance balances recoverable on paid and unpaid losses and settlement expenses are reported separately as assets, instead of being netted with the related liabilities, since reinsurance does not relieve the Company of our legal liability to our policyholders. ​ We continuously monitor the financial condition of our reinsurers. As part of our monitoring efforts, we review their annual financial statements, quarterly disclosures and Securities and Exchange Commission (SEC) filings for reinsurers that are publicly traded. We also review insurance industry developments that may impact the financial condition of our reinsurers. We analyze the credit risk associated with our reinsurance balances recoverable by monitoring the AM Best and Standard & Poor’s (S&P) ratings of our reinsurers. In addition, we subject our reinsurance recoverables to detailed recoverable tests, including one based on average default by S&P rating. Based upon our review and testing, our policy is to charge to earnings, in the form of an allowance, an estimate of unrecoverable amounts from reinsurers. This allowance is reviewed on an ongoing basis to ensure that the amount makes a reasonable provision for reinsurance balances that we may be unable to recover.
POLICY ACQUISITION COSTS	H. POLICY ACQUISITION COSTS ​ We defer incremental direct costs that relate to the successful acquisition of new or renewal insurance contracts, including commissions and premium taxes. Acquisition-related costs may be deemed ineligible for deferral when they are based on contingent or performance criteria beyond the basic acquisition of the insurance contract or when efforts to obtain or renew the insurance contract are unsuccessful. All eligible costs are capitalized and charged to expense in proportion to premium revenue recognized. The method followed in computing deferred policy acquisition costs limits the amount of such deferred costs to their estimated realizable value. This process contemplates the premiums to be earned, anticipated losses and settlement expenses and certain other costs expected to be incurred, but does not consider investment income. Judgments as to the ultimate recoverability of such deferred costs are reviewed on a segment basis and are highly dependent upon estimated future loss costs associated with the premiums written. This deferral methodology applies to both gross and ceded premiums and acquisition costs.
PROPERTY AND EQUIPMENT	I. PROPERTY AND EQUIPMENT ​ Property and equipment are presented at cost less accumulated depreciation and are depreciated on a straight-line basis for financial statement purposes over periods ranging from 3 to 10 years for equipment and up to 30 years for buildings and improvements.
INVESTMENT IN UNCONSOLIDATED INVESTEES	J. INVESTMENTS IN UNCONSOLIDATED INVESTEES ​ We maintain a 40 percent interest in the equity and earnings of Maui Jim, Inc. (Maui Jim), a manufacturer of high-quality sunglasses, which is accounted for under the equity method. We also maintain a similar minority representation on their board of directors. Maui Jim’s chief executive officer owns a controlling majority of the outstanding shares of Maui Jim. We carry this investment at the holding company level as it is not core to our insurance operations. Our investment in Maui Jim was $79.6 million at December 31, 2019 and $79.5 million at December 31, 2018. In 2019, we recorded $13.6 million in investee earnings for Maui Jim, compared to $12.5 million in 2018 and $14.4 million in 2017. Maui Jim recorded net income of $35.6 million in 2019, $30.3 million in 2018 and $34.4 million in 2017. Additional summarized financial information for Maui Jim for 2019 and 2018 is outlined in the following table: ​ ​ ​ ​ ​ ​ ​ ​ ​ (in millions) 2019 2018 Total assets ​ $ 282.2 ​ $ 265.6 ​ Total liabilities ​ 104.8 ​ 90.4 ​ Total equity ​ 177.4 ​ 175.2 ​ ​ Approximately $69.3 million of undistributed earnings from Maui Jim are included in our retained earnings as of December 31, 2019. We received dividends of $13.2 million and $9.9 million from Maui Jim in 2019 and 2018, respectively. No dividends were received in 2017. ​ As of December 31, 2019, we had a 23 percent interest in the equity and earnings of Prime Holdings Insurance Services, Inc. (Prime), which is accounted for under the equity method. Prime writes business through two Illinois domiciled insurance carriers, Prime Insurance Company, an excess and surplus lines company, and Prime Property and Casualty Insurance Inc., an admitted insurance company. Our investment in Prime was $24.2 million at December 31, 2019 and $15.4 million at December 31, 2018. In 2019, we recorded $7.4 million in investee earnings for Prime, compared to $3.6 million in 2018 and $2.8 million in 2017. Additionally, we maintain a quota share reinsurance treaty with Prime, which contributed $13.1 million of gross premiums written and $28.7 million of net premiums earned during 2019, compared to $41.1 million of gross premiums written and $34.2 million of net premiums earned during 2018 and $29.6 million of gross premiums written and $21.0 million of net premiums earned during 2017. The decrease in gross written premium is reflective of our decreased quota share participation with Prime. ​ We perform annual impairment reviews of our investments in unconsolidated investees, which take into consideration current valuation and operating results. Based upon the most recent reviews, the assets were not impaired.
INTANGIBLE ASSETS	K. INTANGIBLE ASSETS ​ Goodwill and intangibles totaled $54.1 million and $54.5 million at December 31, 2019 and 2018, respectively, as detailed in the following table: ​ ​ ​ ​ ​ ​ ​ ​ Goodwill and Intangible Assets ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ 2019 ​ ​ 2018 Goodwill ​ ​ ​ ​ ​ ​ Energy surety ​ $ 25,706 ​ $ 25,706 Miscellaneous and contract surety ​ ​ 15,110 ​ ​ 15,110 Small commercial ​ ​ 5,246 ​ ​ 5,246 Total goodwill ​ $ 46,062 ​ $ 46,062 ​ ​ ​ ​ ​ ​ ​ Intangibles ​ ​ ​ ​ ​ ​ State insurance licenses ​ $ 7,500 ​ $ 7,500 Definite-lived intangibles, net of accumulated amortization of $3,470 ​ ​ 565 ​ ​ 972 Total intangibles ​ $ 8,065 ​ $ 8,472 ​ ​ ​ ​ ​ ​ ​ Total goodwill and intangibles ​ $ 54,127 ​ $ 54,534 ​ As the amortization of goodwill and indefinite-lived intangible assets is not permitted, the assets are tested for impairment on an annual basis, or earlier if there is reason to suspect that their values may have been diminished or impaired. Annual impairment testing was performed on each of our goodwill and indefinite-lived intangible assets during 2019. Based upon these reviews, our energy surety goodwill, miscellaneous and contract surety goodwill, small commercial goodwill and state insurance license indefinite-lived intangible asset were not impaired. In addition, as of December 31, 2019, there were no triggering events on the above-mentioned goodwill and intangible assets that would suggest an updated review was necessary. ​ During the first quarter of 2018 and the second quarter of 2017, adverse loss experience triggered the need to test the medical professional liability reporting unit. The testing resulted in a $4.4 million non-cash impairment charge on goodwill and intangible assets in 2018 and a $3.4 million non-cash impairment charge on goodwill and intangible assets in 2017. In each instance, the fair value for the medical professional liability reporting unit’s agency relationships, carried as a definite-lived intangible asset, was determined by using a discounted cash flow valuation. In 2018, the carrying value exceeded the fair value, resulting in a $0.8 million non-cash impairment charge. In 2017, the resulting non-cash impairment charge on definite-lived intangibles was $1.8 million. The fair value for the medical professional liability reporting unit’s goodwill was determined by using a weighted average of a market approach and discounted cash flow valuation. The carrying value exceeded the fair value in each year, resulting in a $3.6 million non-cash impairment charge in 2018 and a $1.6 million non-cash impairment charge during 2017. Subsequent to the 2018 impairment, the medical professional liability reporting unit had no remaining goodwill or intangible assets. All impairment charges were recorded as net realized losses in the respective period’s consolidated statement of earnings. ​ The definite-lived intangible assets are amortized against future operating results based on their estimated useful lives. Amortization of intangible assets was $0.4 million, $0.4 million and $0.7 million for 2019, 2018 and 2017, respectively. We anticipate we will recognize amortization expense of $0.4 million in 2020, $0.1 million in 2021 and less than $0.1 million in 2022.
UNPAID LOSSES AND SETTLEMENT EXPENSES	L. UNPAID LOSSES AND SETTLEMENT EXPENSES ​ The liability for unpaid losses and settlement expenses represents estimates of amounts needed to pay reported and unreported claims and related expenses. The estimates are based on certain actuarial and other assumptions related to the ultimate cost to settle such claims. Such assumptions are subject to occasional changes due to evolving economic, social and political conditions. All estimates are periodically reviewed and, as experience develops and new information becomes known, the reserves are adjusted as necessary. Such adjustments are reflected in the results of operations in the period in which they are determined. Due to the inherent uncertainty in estimating reserves for losses and settlement expenses, there can be no assurance that the ultimate liability will not exceed recorded amounts. If actual liabilities do exceed recorded amounts, there will be an adverse effect. Furthermore, we may determine that recorded reserves are more than adequate to cover expected losses, which would lead to a reduction in our reserves.
INSURANCE REVENUE RECOGNITION	M. INSURANCE REVENUE RECOGNITION ​ Insurance premiums are recognized ratably over the term of the contracts, net of ceded reinsurance. Unearned premiums are calculated on a monthly pro rata basis.
INCOME TAXES	N. INCOME TAXES ​ We file a consolidated federal income tax return. Federal income taxes are accounted for using the asset and liability method under which deferred income taxes are recognized for the tax consequences of temporary differences by applying enacted statutory tax rates applicable to future years to differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities, operating losses and tax credit carry forwards. The effect on deferred taxes for a change in tax rates is recognized in income in the period that includes the enactment date. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some of the deferred tax assets will not be realized. ​ We consider uncertainties in income taxes and recognize those in our financial statements as required. As it relates to uncertainties in income taxes, our unrecognized tax benefits, including interest and penalty accruals, are not considered material to the consolidated financial statements. Also, no tax uncertainties are expected to result in significant increases or decreases to unrecognized tax benefits within the next 12-month period. Penalties and interest related to income tax uncertainties, should they occur, would be included in income tax expense in the period in which they are incurred. ​ As an insurance company, we are subject to minimal state income tax liabilities. On a state basis, since the majority of our income is from insurance operations, we pay premium taxes which are calculated as a percentage of gross premiums written in lieu of state income taxes. Premium taxes are a component of policy acquisition costs.
EARNINGS PER SHARE	O. EARNINGS PER SHARE ​ Basic earnings per share (EPS) is computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted EPS reflects the dilution that could occur if securities or other contracts to issue common stock or common stock equivalents were exercised or converted into common stock. When inclusion of these items increases the earnings per share or reduces the loss per share, the effect on earnings is anti-dilutive. Under these circumstances, the diluted net earnings or net loss per share is computed excluding these items. The following represents a reconciliation of the numerator and denominator of the basic and diluted EPS computations contained in the consolidated financial statements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average ​ ​ ​ ​ Income ​ Shares ​ Per Share (in thousands, except per share data) ​ (Numerator) ​ (Denominator) ​ Amount For the year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 191,642 44,734 ​ $ 4.28 ​ Stock options ​ — 523 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 191,642 45,257 ​ $ 4.23 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 64,179 44,358 ​ $ 1.45 ​ Stock options ​ — 477 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 64,179 44,835 ​ $ 1.43 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 105,028 44,033 ​ $ 2.39 ​ Stock options ​ — 467 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 105,028 44,500 ​ $ 2.36 ​
COMPREHENSIVE EARNINGS	P. COMPREHENSIVE EARNINGS ​ Financial Instruments – Overall (subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, ​ The table below illustrates the changes in the balance of each component of accumulated other comprehensive earnings for each period presented in the consolidated financial statements. The 2017 activity and balances include the net unrealized gain and loss activity on both fixed income and equity securities, while the 2019 and 2018 activity and ending balance reflect only the net unrealized gain and loss activity on fixed income securities due to the aforementioned adoption of ASU 2016-01. The changes in accumulated other comprehensive earnings also reflect adjustments from the adoption of two accounting standards. ASU 2016-01 necessitated a cumulative-effect adjustment in the beginning of 2018, which moved $142.2 million of net unrealized gains and losses on equity securities from accumulated other comprehensive earnings to retained earnings. ​ ASU 2018-02 addressed issues arising from the enactment of the Tax Cuts and Jobs Act of 2017. Deferred tax items are required to be revalued based on new tax laws with changes included in earnings. Since other comprehensive earnings was not affected by the revaluation of deferred tax items, the accumulated other comprehensive earnings balance was reflective of the historic tax rate instead of the newly enacted rate, which created a stranded tax effect. ASU 2018-02 allowed for the reclassification of our $3.7 million stranded tax effect out of accumulated other comprehensive earnings into retained earnings. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains/Losses on Available-for-Sale Securities ​ For the Year Ended December 31, (in thousands) 2019 2018 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning balance ​ $ (14,572) $ 157,919 $ 122,610 ​ Cumulative effect adjustment of ASU 2016-01 ​ ​ — ​ ​ (142,219) ​ ​ — ​ Adjusted beginning balance ​ $ (14,572) ​ $ 15,700 ​ $ 122,610 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive earnings before reclassifications ​ 69,560 (35,763) 40,887 ​ Amounts reclassified from accumulated other comprehensive earnings ​ (2,515) 1,766 (5,578) ​ Net current-period other comprehensive earnings (loss) ​ $ 67,045 $ (33,997) $ 35,309 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification of stranded tax effect from implementation of Tax Cuts and Jobs Act of 2017 ​ ​ — ​ ​ 3,725 ​ ​ — ​ Ending balance ​ $ 52,473 $ (14,572) $ 157,919 ​ ​ The sale or other-than-temporary impairment of an available-for-sale security results in amounts being reclassified from accumulated other comprehensive earnings to current period net earnings. The effects of reclassifications out of accumulated other comprehensive earnings by the respective line items of net earnings are presented in the following table. As previously mentioned, 2019 and 2018 reflect activity on available-for-sale fixed income securities, while 2017 also includes activity from the equity portfolio. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount Reclassified from Accumulated Other Comprehensive Earnings (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Component of Accumulated ​ For the Year Ended December 31, ​ Affected line item in the Other Comprehensive Earnings 2019 2018 2017 Consolidated Statement of Earnings ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized gains and losses on available-for-sale securities ​ $ 3,184 $ (2,018) $ 11,141 Net ​ ​ ​ — (217) (2,559) Other-than-temporary impairment losses on investments ​ ​ ​ $ 3,184 $ (2,235) $ 8,582 Earnings before income taxes ​ ​ ​ (669) 469 (3,004) Income tax expense ​ ​ ​ $ 2,515 $ (1,766) $ 5,578 Net earnings ​
FAIR VALUE DISCLOSURES	Q. FAIR VALUE DISCLOSURES ​ Fair value is defined as the price in the principal market that would be received for an asset to facilitate an orderly transaction between market participants on the measurement date. We determined the fair value of certain financial instruments based on their underlying characteristics and relevant transactions in the marketplace. We maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. ​ The following are the levels of the fair value hierarchy and a brief description of the type of valuation inputs that are used to establish each level. Financial assets are classified based upon the lowest level of significant input that is used to determine fair value. ​ ● Pricing Level 1 is applied to valuations based on readily available, unadjusted quoted prices in active markets for identical assets. ​ ● Pricing Level 2 is applied to valuations based upon quoted prices for similar assets in active markets, quoted prices for identical or similar assets in inactive markets; or valuations based on models where the significant inputs are observable (e.g. interest rates, yield curves, prepayment speeds, default rates, loss severities) or can be corroborated by observable market data. ​ ● Pricing Level 3 is applied to valuations that are derived from techniques in which one or more of the significant inputs are unobservable. ​ As a part of management’s process to determine fair value, we utilize widely recognized, third-party pricing sources to determine our fair values. We have obtained an understanding of the third-party pricing sources’ valuation methodologies and inputs. The following is a description of the valuation techniques used for financial assets that are measured at fair value, including the general classification of such assets pursuant to the fair value hierarchy. ​ Corporate, Agencies, Government and Municipal Bonds: ​ Mortgage-backed Securities (MBS)/Collateralized Mortgage Obligations (CMO) and Asset-backed Securities (ABS): ​ Regulation D Private Placement Securities: ​ For all of our fixed income securities, we periodically conduct a review to assess the reasonableness of the fair values provided by our pricing services. Our review consists of a two-pronged approach. First, we compare prices provided by our pricing services to those provided by an additional source. In some cases, we obtain prices from securities brokers and compare them to the prices provided by our pricing services. In our comparisons, if discrepancies are found, we compare our prices to actual reported trade data for like securities. No changes to the fair values supplied by our pricing services have occurred as a result of our reviews. Based on these assessments, we have determined that the fair values of our fixed income securities provided by our pricing services are reasonable. ​ Common Stock: ​ Due to the relatively short-term nature of cash, short-term investments, accounts receivable and accounts payable, their carrying amounts are reasonable estimates of fair value. Our investments in private funds, classified as other invested assets, are measured using the investments’ net asset value per share and are not categorized within the fair value hierarchy. The fair value of our long-term debt is discussed further in note 4.
STOCK-BASED COMPENSATION	R. STOCK-BASED COMPENSATION ​ We expense the estimated fair value of employee stock options and similar awards. We measure compensation cost for awards of equity instruments to employees based on the grant-date fair value of those awards and recognize compensation expense over the service period that the awards are expected to vest. The tax effects related to share-based payments are made through net earnings. See note 8 for further discussion and related disclosures regarding stock options.
RISKS AND UNCERTAINTIES	S. RISKS AND UNCERTAINTIES ​ Certain risks and uncertainties are inherent to our day-to-day operations and to the process of preparing our consolidated financial statements. The more significant risks and uncertainties, as well as our attempt to mitigate, quantify and minimize such risks, are presented below and throughout the notes to the consolidated financial statements. ​ Insurance Risks ​ We compete with a large number of other companies in our selected lines of business. During periods of intense competition for premium, we are vulnerable to the actions of other companies who may seek to write business without the appropriate regard for risk and profitability. The insurance industry is currently operating under highly competitive conditions and, as a result, margins in the industry are under pressure. During these times, it is very difficult to grow or maintain premium volume without sacrificing underwriting discipline and income. Our profitability can be significantly affected by the ability of our underwriters to accurately select and price risk and our claim personnel to appropriately deliver fair outcomes. We attempt to mitigate this risk by incentivizing our underwriters to maximize underwriting profit and remain disciplined in pricing and selecting risks. If we are unable to compete effectively in the markets in which we operate or expand our operations into new markets, our underwriting revenues may decline, as well as overall business results. ​ Our loss reserves are based on estimates and may be inadequate to cover our actual insured losses, which would negatively impact our profitability. As of December 31, 2019, we had $1.6 billion of gross loss and LAE reserves. Significant periods of time often elapse between the occurrence of an insured loss, the reporting of the loss to the Company and our payment of that loss. As part of the reserving process, we review historical data and consider the impact of various factors such as trends in claim frequency and severity, emerging economic and social trends, inflation and changes in the regulatory and litigation environments. If the actual amount of insured losses is greater than the amount we have reserved for these losses, our profitability would suffer. ​ Catastrophe Exposures ​ Our insurance coverages include exposure to catastrophic events. We monitor all catastrophe exposures by quantifying our exposed policy limits in each region and by using computer-assisted modeling techniques. Additionally, we limit our risk to such catastrophes through restraining the total policy limits written in each region and by purchasing reinsurance. Our major catastrophe exposure is to losses caused by earthquakes, primarily on the West Coast. In 2019, we had reinsurance protection of $400 million in excess of $25 million first-dollar retention for earthquakes in California and $425 million in excess of a $25 million first-dollar retention for earthquakes outside of California. These amounts are subject to certain co-participations by the Company on losses in excess of the $25 million retentions. Our second largest catastrophe exposure is to losses caused by wind storms to commercial properties throughout the Gulf and East Coasts, as well as to homes we insure in Hawaii. In 2019, these coverages were supported by $275 million in excess of a $25 million first-dollar retention in traditional catastrophe reinsurance protection, subject to certain co-participations by the Company in the excess layers. In addition, we have incidental exposure to international catastrophic events. ​ Our catastrophe reinsurance treaty renewed on January 1, 2020. We purchased the same limits over the same first-dollar retention amounts outlined above, subject to certain retentions by us in the excess layers. We actively manage our catastrophe program to keep our net retention in line with risk tolerances and to optimize the risk/return trade off. ​ Environmental Exposures ​ We are subject to environmental claims and exposures primarily through our commercial excess, general liability and discontinued assumed casualty reinsurance lines of business. Although exposure to environmental claims exists in these lines of business, we seek to mitigate or control the extent of this exposure on the vast majority of this business through the following methods: (1) our policies include pollution exclusions that have been continually updated to further strengthen them, (2) our policies primarily cover moderate hazard risks and (3) we began writing this business after the insurance industry became aware of the potential pollution liability exposure and implemented changes to limit exposure to this hazard. ​ We offer coverage for low to moderate environmental liability exposures for small contractors and asbestos and mold remediation specialists. We also provide limited coverage for individually underwritten underground storage tanks. The overall exposure is mitigated by focusing on smaller risks with low to moderate exposures. Risks that have large-scale exposures are avoided including petrochemical, chemical, mining, manufacturers and other risks that might be exposed to superfund sites. This business is covered under our casualty ceded reinsurance treaties. ​ We made loss and settlement expense payments on environmental liability claims and have loss and settlement expense reserves for others. We include this historical environmental loss experience with the remaining loss experience in the applicable line of business to project ultimate incurred losses and settlement expenses as well as related incurred but not reported (IBNR) loss and settlement expense reserves. ​ Although historical experience on environmental claims may not accurately reflect future environmental exposures, we used this experience to record loss and settlement expense reserves in the exposed lines of business. See further discussion of environmental exposures in note 6. ​ Reinsurance ​ Reinsurance does not discharge the Company from our primary liability to policyholders, and to the extent that a reinsurer is unable to meet its obligations, we would be liable. We continuously monitor the financial condition of prospective and existing reinsurers. As a result, we purchase reinsurance from a number of financially strong reinsurers. We provide an allowance for reinsurance balances deemed uncollectible. See further discussion of reinsurance exposures in note 5. ​ Investment Risk ​ Our investment portfolio is subject to market, credit and interest rate risks. The equity portfolio will fluctuate with movements in the overall stock market. While the equity portfolio has been constructed to have lower downside risk than the market, the portfolio is positively correlated with movements in domestic stocks. The bond portfolio is affected by interest rate changes and movement in credit spreads. We attempt to mitigate our interest rate and credit risks by constructing a well-diversified portfolio with high-quality securities with varied maturities. Downturns in the financial markets could have a negative effect on our portfolio. However, we attempt to manage this risk through asset allocation, duration and security selection. ​ Liquidity Risk ​ Liquidity is essential to our business and a key component of our concept of asset-liability matching. Our liquidity may be impaired by an inability to collect premium receivable or reinsurance recoverable balances in a timely manner, an inability to sell assets or redeem our investments, an inability to access funds from our insurance subsidiaries, unforeseen outflows of cash or large claim payments or an inability to access debt or equity capital markets. This situation may arise due to circumstances that we may be unable to control, such as a general market disruption, an operational problem that affects third parties or the Company, or even by the perception among market participants that we, or other market participants, are experiencing greater liquidity risk. ​ Our credit ratings are important to our liquidity. A reduction in our credit ratings could adversely affect our liquidity and competitive position by increasing our borrowing costs or limiting our access to the capital markets. ​ Financial Statements ​ The preparation of the accompanying consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenues and expenses. The most significant of these amounts is the liability for unpaid losses and settlement expenses. Other estimates include investment valuation and OTTIs, the collectability of reinsurance balances, recoverability of deferred tax assets and deferred policy acquisition costs. These estimates and assumptions are based on management’s best estimates and judgment. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, which management believes to be reasonable under the circumstances. We adjust such estimates and assumptions when facts and circumstances dictate. Although recorded estimates are supported by actuarial computations and other supportive data, the estimates are ultimately based on our expectations of future events. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Changes in those estimates resulting from continuing changes in the economic environment will be reflected in the consolidated financial statements in future periods. ​ External Factors ​ Our insurance subsidiaries are highly regulated by the state in which they are incorporated and by the states in which they do business. Such regulations, among other things, limit the amount of dividends, impose restrictions on the amount and types of investments and regulate rates insurers may charge for various coverages. We are also subject to insolvency and guaranty fund assessments for various programs designed to ensure policyholder indemnification. We generally accrue an assessment during the period in which it becomes probable that a liability has been incurred from an insolvency and the amount of the related assessment can be reasonably estimated. ​ The National Association of Insurance Commissioners (NAIC) has developed Property/Casualty Risk-Based Capital (RBC) standards that relate an insurer’s reported statutory surplus to the risks inherent in its overall operations. The RBC formula uses the statutory annual statement to calculate the minimum indicated capital level to support investment and underwriting risk. The NAIC model law calls for various levels of regulatory action based on the magnitude of an indicated RBC capital deficiency, if any. We regularly monitor our subsidiaries’ internal capital requirements and the NAIC’s RBC developments. As of December 31, 2019, we determined that our capital levels are well in excess of the minimum capital requirements for all RBC action levels and that our capital levels are sufficient to support the level of risk inherent in our operations. See note 9 for further discussion of statutory information and related insurance regulatory restrictions. ​ In addition, ratings are a critical factor in establishing the competitive position of insurance companies. Our insurance companies are rated by AM Best, S&P and Moody’s. Their ratings reflect their opinions of an insurance company’s and an insurance holding company’s financial strength, operating performance, strategic position and ability to meet its obligations to policyholders.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of summarized financial information of Maui Jim	​ ​ ​ ​ ​ ​ ​ ​ ​ (in millions) 2019 2018 Total assets ​ $ 282.2 ​ $ 265.6 ​ Total liabilities ​ 104.8 ​ 90.4 ​ Total equity ​ 177.4 ​ 175.2 ​
Schedule of goodwill and intangible assets	​ ​ ​ ​ ​ ​ ​ ​ Goodwill and Intangible Assets ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ 2019 ​ ​ 2018 Goodwill ​ ​ ​ ​ ​ ​ Energy surety ​ $ 25,706 ​ $ 25,706 Miscellaneous and contract surety ​ ​ 15,110 ​ ​ 15,110 Small commercial ​ ​ 5,246 ​ ​ 5,246 Total goodwill ​ $ 46,062 ​ $ 46,062 ​ ​ ​ ​ ​ ​ ​ Intangibles ​ ​ ​ ​ ​ ​ State insurance licenses ​ $ 7,500 ​ $ 7,500 Definite-lived intangibles, net of accumulated amortization of $3,470 ​ ​ 565 ​ ​ 972 Total intangibles ​ $ 8,065 ​ $ 8,472 ​ ​ ​ ​ ​ ​ ​ Total goodwill and intangibles ​ $ 54,127 ​ $ 54,534
Schedule of reconciliation of numerator and denominator of the basic and diluted earnings per share computations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average ​ ​ ​ ​ Income ​ Shares ​ Per Share (in thousands, except per share data) ​ (Numerator) ​ (Denominator) ​ Amount For the year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 191,642 44,734 ​ $ 4.28 ​ Stock options ​ — 523 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 191,642 45,257 ​ $ 4.23 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 64,179 44,358 ​ $ 1.45 ​ Stock options ​ — 477 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 64,179 44,835 ​ $ 1.43 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders ​ $ 105,028 44,033 ​ $ 2.39 ​ Stock options ​ — 467 ​ ​ ​ ​ Diluted EPS ​ ​ ​ ​ ​ ​ ​ ​ ​ Income available to common shareholders and assumed conversions ​ $ 105,028 44,500 ​ $ 2.36 ​
Schedule of changes in the balance of each component of accumulated other comprehensive earnings	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains/Losses on Available-for-Sale Securities ​ For the Year Ended December 31, (in thousands) 2019 2018 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning balance ​ $ (14,572) $ 157,919 $ 122,610 ​ Cumulative effect adjustment of ASU 2016-01 ​ ​ — ​ ​ (142,219) ​ ​ — ​ Adjusted beginning balance ​ $ (14,572) ​ $ 15,700 ​ $ 122,610 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive earnings before reclassifications ​ 69,560 (35,763) 40,887 ​ Amounts reclassified from accumulated other comprehensive earnings ​ (2,515) 1,766 (5,578) ​ Net current-period other comprehensive earnings (loss) ​ $ 67,045 $ (33,997) $ 35,309 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification of stranded tax effect from implementation of Tax Cuts and Jobs Act of 2017 ​ ​ — ​ ​ 3,725 ​ ​ — ​ Ending balance ​ $ 52,473 $ (14,572) $ 157,919 ​
Schedule of effects of reclassifications out of accumulated other comprehensive earnings	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount Reclassified from Accumulated Other Comprehensive Earnings (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Component of Accumulated ​ For the Year Ended December 31, ​ Affected line item in the Other Comprehensive Earnings 2019 2018 2017 Consolidated Statement of Earnings ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized gains and losses on available-for-sale securities ​ $ 3,184 $ (2,018) $ 11,141 Net ​ ​ ​ — (217) (2,559) Other-than-temporary impairment losses on investments ​ ​ ​ $ 3,184 $ (2,235) $ 8,582 Earnings before income taxes ​ ​ ​ (669) 469 (3,004) Income tax expense ​ ​ ​ $ 2,515 $ (1,766) $ 5,578 Net earnings ​

INVESTMENTS (Tables)

INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2019
INVESTMENTS
Schedule of net investment income	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NET INVESTMENT INCOME ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Interest on fixed income securities $ 60,364 $ 54,491 $ 48,343 ​ Dividends on equity securities ​ 9,950 ​ 9,814 ​ 10,506 ​ Interest on cash, short-term investments and other invested assets ​ 3,674 ​ 2,309 ​ 945 ​ Gross investment income ​ $ 73,988 ​ $ 66,614 ​ $ 59,794 ​ Less investment expenses ​ (5,118) ​ (4,529) ​ (4,918) ​ Net investment income $ 68,870 ​ $ 62,085 ​ $ 54,876 ​
Schedule of pretax net realized investment gains (losses) and net changes in unrealized gains (losses) on investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ REALIZED/UNREALIZED GAINS (LOSSES) ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Net realized gains (losses): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed income: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 3,184 ​ $ (2,018) ​ $ 859 ​ Equity securities ​ 14,445 ​ 69,868 ​ 10,282 ​ Other ​ (109) ​ (4,226) ​ (4,171) ​ Total net realized gains (losses) ​ $ 17,520 ​ $ 63,624 ​ $ 6,970 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other-than-temporary-impairment losses on investments ​ $ — ​ $ (217) ​ $ (2,559) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net changes in unrealized gains (losses) on investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities ​ $ 78,389 ​ $ (98,380) ​ $ — ​ Other invested assets ​ ​ (299) ​ ​ (355) ​ ​ — ​ Total unrealized gains (losses) on equity securities recognized in net earnings ​ $ 78,090 ​ $ (98,735) ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed income: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 83,758 ​ $ (41,778) ​ $ 16,846 ​ Equity securities ​ ​ — ​ ​ — ​ ​ 36,844 ​ Other invested assets ​ ​ — ​ ​ — ​ ​ 29 ​ Investment in unconsolidated investees ​ ​ 1,109 ​ ​ (1,257) ​ ​ 604 ​ Total unrealized gains (losses) recognized in other comprehensive earnings ​ $ 84,867 ​ $ (43,035) ​ $ 54,323 ​ Net realized gains (losses) and changes in unrealized gains (losses) on investments ​ $ 180,477 ​ $ (78,363) ​ $ 58,734 ​
Schedule of disposition of fixed maturities and equities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net SALES ​ ​ ​ Gross Realized ​ Realized (in thousands) Proceeds Gains Losses Gain (Loss) ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 196,799 ​ $ 4,368 ​ $ (2,167) ​ $ 2,201 ​ Equities ​ 62,172 ​ 16,938 ​ (2,493) ​ 14,445 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 394,318 ​ $ 3,131 ​ $ (5,349) ​ $ (2,218) ​ Equities ​ 147,838 ​ 71,065 ​ (1,197) ​ 69,868 ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 169,002 ​ $ 2,406 ​ $ (1,670) ​ $ 736 ​ Equities ​ 36,573 ​ 13,178 ​ (2,896) ​ 10,282 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net CALLS/MATURITIES ​ ​ ​ ​ Gross Realized ​ Realized (in thousands) Proceeds Gains Losses Gain (Loss) 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 201,698 ​ $ 1,004 ​ $ (21) ​ $ 983 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 187,380 ​ $ 311 ​ $ (111) ​ $ 200 ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 195,617 ​ $ 262 ​ $ (139) ​ $ 123 ​ ​
Fair Value, Assets Measured on Recurring Basis	Assets measured at fair value on a recurring basis as of December 31, 2019, are summarized below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted in Active ​ Significant Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ ​ ​ (in thousands) ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Total Fixed income securities - available-for-sale ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ — ​ $ 193,661 ​ $ — ​ $ 193,661 ​ U.S. agency ​ ​ — ​ ​ 38,855 ​ ​ — ​ ​ 38,855 ​ Non-U.S. government & agency ​ — ​ 7,628 ​ — ​ 7,628 ​ Agency MBS ​ — ​ 420,165 ​ — ​ 420,165 ​ ABS/CMBS/MBS* ​ — ​ 224,870 ​ — ​ 224,870 ​ Corporate ​ — ​ 690,297 ​ 1,770 ​ 692,067 ​ Municipal ​ — ​ 405,840 ​ — ​ 405,840 ​ Total fixed income securities - available-for-sale ​ $ — ​ $ 1,981,316 ​ $ 1,770 ​ $ 1,983,086 ​ Equity securities ​ 460,630 ​ — ​ — ​ 460,630 ​ Total ​ $ 460,630 ​ $ 1,981,316 ​ $ 1,770 ​ $ 2,443,716 ​ *Non-agency asset-backed, commercial mortgage-backed and mortgage-backed ​ Assets measured at fair value on a recurring basis as of December 31, 2018, are summarized below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted in Active ​ Significant Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ ​ ​ (in thousands) ​ (Level 1) ​ (Level 2) ​ (Level 3) ​ Total Fixed income securities - available-for-sale ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ — ​ $ 200,229 ​ $ — ​ $ 200,229 ​ U.S. agency ​ ​ — ​ ​ 31,904 ​ ​ — ​ ​ 31,904 ​ Non-U.S. government & agency ​ — ​ 7,639 ​ — ​ 7,639 ​ Agency MBS ​ — ​ 395,253 ​ — ​ 395,253 ​ ABS/CMBS/MBS* ​ — ​ 136,723 ​ — ​ 136,723 ​ Corporate ​ — ​ 668,679 ​ — ​ 668,679 ​ Municipal ​ — ​ 320,088 ​ — ​ 320,088 ​ Total fixed income securities - available-for-sale ​ $ — ​ $ 1,760,515 ​ $ — ​ $ 1,760,515 ​ Equity securities ​ 339,985 ​ 498 ​ — ​ 340,483 ​ Total ​ $ 339,985 ​ $ 1,761,013 ​ $ — ​ $ 2,100,998 ​ *Non-agency asset-backed, commercial mortgage-backed and mortgage-backed
Schedule of contractual maturity of securities	The amortized cost and estimated fair value of fixed income securities at December 31, 2019, by contractual maturity, are shown as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Amortized Cost Fair Value Available-for-sale ​ ​ ​ ​ ​ ​ ​ Due in one year or less ​ $ 49,951 ​ $ 50,170 ​ Due after one year through five years ​ 395,056 ​ 407,007 ​ Due after five years through 10 years ​ 580,310 ​ 613,099 ​ Due after 10 years ​ 255,321 ​ 267,775 ​ Mtge/ABS/CMBS* ​ 634,640 ​ 645,035 ​ Total available-for-sale ​ $ 1,915,278 ​ $ 1,983,086 ​ *
Schedule of amortized cost and fair value of available-for-sale securities	The following table is a schedule of amortized costs and estimated fair values of investments in fixed income securities as of December 31, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 ​ Amortized ​ ​ ​ ​ Gross Unrealized (in thousands) Cost Fair Value Gains Losses Available-for-sale ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ 186,699 ​ $ 193,661 ​ $ 6,994 ​ $ (32) ​ U.S. agency ​ 36,535 ​ 38,855 ​ 2,362 ​ (42) ​ Non-U.S. government & agency ​ 7,333 ​ 7,628 ​ 295 ​ — ​ Agency MBS ​ 411,808 ​ 420,165 ​ 8,920 ​ (563) ​ ABS/CMBS/MBS* ​ ​ 222,832 ​ ​ 224,870 ​ ​ 2,514 ​ ​ (476) ​ Corporate ​ 659,640 ​ 692,067 ​ 33,245 ​ (818) ​ Municipal ​ 390,431 ​ 405,840 ​ 16,131 ​ (722) ​ Total fixed income ​ $ 1,915,278 ​ $ 1,983,086 ​ $ 70,461 ​ $ (2,653) ​ * ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2018 ​ Amortized ​ ​ ​ ​ Gross Unrealized (in thousands) Cost Fair Value Gains Losses Available-for-sale ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government ​ $ 199,982 ​ $ 200,229 ​ $ 1,232 ​ $ (985) ​ U.S. agency ​ 31,716 ​ 31,904 ​ 403 ​ (215) ​ Non-U.S. government & agency ​ 8,170 ​ 7,639 ​ — ​ (531) ​ Agency MBS ​ 402,992 ​ 395,253 ​ 1,709 ​ (9,448) ​ ABS/CMBS/MBS* ​ ​ 137,224 ​ ​ 136,723 ​ ​ 375 ​ ​ (876) ​ Corporate ​ 681,909 ​ 668,679 ​ 2,894 ​ (16,124) ​ Municipal ​ 314,472 ​ 320,088 ​ 6,926 ​ (1,310) ​ Total fixed income ​ $ 1,776,465 ​ $ 1,760,515 ​ $ 13,539 ​ $ (29,489) ​ *
Schedule of securities in an unrealized loss position segregated by type and length of time in an unrealized loss position	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 ​ December 31, 2018 ​ ​ ​ 12 Mos. ​ ​ ​ ​ 12 Mos. ​ ​ (in thousands) ​ < 12 Mos. ​ & Greater ​ Total ​ < 12 Mos. ​ & Greater ​ Total U.S. government ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 2,505 ​ $ 8,463 ​ $ 10,968 ​ $ 7,249 ​ $ 76,073 ​ $ 83,322 ​ Amortized cost ​ 2,506 ​ 8,494 ​ 11,000 ​ 7,270 ​ 77,037 ​ 84,307 ​ Unrealized loss ​ $ (1) ​ $ (31) ​ $ (32) ​ $ (21) ​ $ (964) ​ $ (985) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. agency ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 6,794 ​ $ — ​ $ 6,794 ​ $ — ​ $ 8,843 ​ $ 8,843 ​ Amortized cost ​ 6,836 ​ — ​ 6,836 ​ — ​ 9,058 ​ 9,058 ​ Unrealized loss ​ $ (42) ​ $ — ​ $ (42) ​ $ — ​ $ (215) ​ $ (215) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-U.S. government & agency ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ — ​ $ — ​ $ — ​ $ 5,432 ​ $ 2,207 ​ $ 7,639 ​ Amortized cost ​ — ​ — ​ — ​ 5,571 ​ 2,599 ​ 8,170 ​ Unrealized loss ​ $ — ​ $ — ​ $ — ​ $ (139) ​ $ (392) ​ $ (531) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Agency MBS ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 21,548 ​ $ 41,718 ​ $ 63,266 ​ $ 25,345 ​ $ 261,325 ​ $ 286,670 ​ Amortized cost ​ 21,664 ​ 42,165 ​ 63,829 ​ 25,486 ​ 270,632 ​ 296,118 ​ Unrealized loss ​ $ (116) ​ $ (447) ​ $ (563) ​ $ (141) ​ $ (9,307) ​ $ (9,448) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ABS/CMBS/MBS* ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 74,968 ​ $ 18,036 ​ $ 93,004 ​ $ 46,918 ​ $ 32,137 ​ $ 79,055 ​ Amortized cost ​ 75,332 ​ 18,148 ​ 93,480 ​ 47,146 ​ 32,785 ​ 79,931 ​ Unrealized loss ​ $ (364) ​ $ (112) ​ $ (476) ​ $ (228) ​ $ (648) ​ $ (876) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 16,478 ​ $ 9,348 ​ $ 25,826 ​ $ 306,177 ​ $ 147,751 ​ $ 453,928 ​ Amortized cost ​ 16,950 ​ 9,694 ​ 26,644 ​ 315,428 ​ 154,624 ​ 470,052 ​ Unrealized loss ​ $ (472) ​ $ (346) ​ $ (818) ​ $ (9,251) ​ $ (6,873) ​ $ (16,124) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Municipal ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 47,018 ​ $ — ​ $ 47,018 ​ $ 6,036 ​ $ 55,681 ​ $ 61,717 ​ Amortized cost ​ 47,740 ​ — ​ 47,740 ​ 6,052 ​ 56,975 ​ 63,027 ​ Unrealized loss ​ $ (722) ​ $ — ​ $ (722) ​ $ (16) ​ $ (1,294) ​ $ (1,310) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed income ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value ​ $ 169,311 ​ $ 77,565 ​ $ 246,876 ​ $ 397,157 ​ $ 584,017 ​ $ 981,174 ​ Amortized cost ​ 171,028 ​ 78,501 ​ 249,529 ​ 406,953 ​ 603,710 ​ 1,010,663 ​ Unrealized loss ​ $ (1,717) ​ $ (936) ​ $ (2,653) ​ $ (9,796) ​ $ (19,693) ​ $ (29,489) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ *Non-agency asset-backed and commercial mortgage-backed

POLICY ACQUISITION COSTS (Table

POLICY ACQUISITION COSTS (Tables)	12 Months Ended
	Dec. 31, 2019
POLICY ACQUISITION COSTS
Schedule of policy acquisition costs deferred and amortized to income	Policy acquisition costs deferred and amortized to income for the years ended December 31 are summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Deferred policy acquisition costs (DAC), beginning of year ​ $ 84,934 ​ $ 77,716 ​ $ 73,147 ​ Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Direct commissions ​ $ 185,164 ​ $ 175,697 ​ $ 157,723 ​ Premium taxes ​ 14,395 ​ 12,654 ​ 11,651 ​ Ceding commissions ​ (31,140) ​ (22,190) ​ (18,096) ​ Net deferred ​ $ 168,419 ​ $ 166,161 ​ $ 151,278 ​ Amortized ​ 168,309 ​ 158,943 ​ 146,709 ​ DAC, end of year ​ $ 85,044 ​ $ 84,934 ​ $ 77,716 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Policy acquisition costs: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized to expense - DAC ​ $ 168,309 ​ $ 158,943 ​ $ 146,709 ​ Period costs: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ceding commission - contingent ​ (3,034) ​ (2,241) ​ (3,575) ​ Other underwriting expenses ​ 123,422 ​ 111,036 ​ 109,381 ​ Total policy acquisition costs ​ $ 288,697 ​ $ 267,738 ​ $ 252,515 ​

REINSURANCE (Tables)

REINSURANCE (Tables)	12 Months Ended
	Dec. 31, 2019
REINSURANCE
Schedule of premiums written and earned along with losses and settlement expenses incurred	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 WRITTEN ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Direct $ 1,039,955 $ 934,913 $ 848,153 ​ Reinsurance assumed ​ 25,047 ​ 48,303 ​ 37,159 ​ Reinsurance ceded ​ (204,665) ​ (160,041) ​ (135,458) ​ Net ​ $ 860,337 ​ $ 823,175 ​ $ 749,854 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ EARNED ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Direct ​ $ 981,121 ​ $ 896,234 ​ $ 835,118 ​ Reinsurance assumed ​ 40,173 ​ 41,926 ​ 32,521 ​ Reinsurance ceded ​ (182,183) ​ (146,794) ​ (129,702) ​ Net ​ $ 839,111 ​ $ 791,366 ​ $ 737,937 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ LOSSES AND SETTLEMENT EXPENSES INCURRED ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Direct ​ $ 521,055 ​ $ 560,421 ​ $ 486,986 ​ Reinsurance assumed ​ 21,951 ​ 20,376 ​ 16,072 ​ Reinsurance ceded ​ (129,590) ​ (152,604) ​ (101,474) ​ Net ​ $ 413,416 ​ $ 428,193 ​ $ 401,584 ​
Schedule of net reinsurance balances recoverable, after consideration of collateral, from top 10 reinsurers	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Reinsurer ​ Ceded ​ ​ AM Best ​ S & P ​ Exposure as of ​ Percent of ​ ​ Premiums ​ Percent of (dollars in thousands) ​ Rating ​ Rating ​ 12/31/2019 ​ Total ​ ​ Written ​ Total Munich Re / HSB A+, Superior AA-, Very Strong ​ $ 68,368 14.6 % ​ $ 22,536 11.0 % Swiss Re / Westport Ins. Corp. A+, Superior AA-, Very Strong ​ 34,777 7.4 % ​ 2,801 1.4 % Endurance Re A+, Superior A+, Strong ​ 32,233 6.9 % ​ 9,173 4.5 % Aspen UK Ltd. A, Excellent A, Strong ​ 31,622 6.7 % ​ 8,270 4.0 % Berkley Insurance Co. A+, Superior A+, Strong ​ 28,798 6.1 % ​ 8,667 4.2 % Renaissance Re ​ A+, Superior A+, Strong ​ ​ 25,841 ​ 5.5 % ​ ​ 15,754 ​ 7.7 % Hannover Ruckversicherung A+, Superior AA-, Very Strong ​ 24,758 5.3 % ​ 12,491 6.1 % Toa Re ​ A, Excellent ​ A+, Strong ​ 23,734 5.1 % ​ 7,757 3.8 % Transatlantic Re A+, Superior A+, Strong ​ 22,873 4.9 % ​ 6,635 3.2 % General Re A++, Superior AA+, Very Strong ​ 19,736 4.2 % ​ 6,240 3.0 % Liberty Mutual ​ A, Excellent ​ A, Strong ​ ​ 19,171 ​ 4.1 % ​ ​ 6,696 ​ 3.3 % All other reinsurers* ​ ​ ​ ​ ​ 137,240 29.2 % ​ 97,645 47.8 % Total ceded exposure ​ ​ ​ ​ ​ $ 469,151 100.0 % ​ $ 204,665 100.0 % *

HISTORICAL LOSS AND LAE DEVEL_2

HISTORICAL LOSS AND LAE DEVELOPMENT (Tables)	12 Months Ended
	Dec. 31, 2019
HISTORICAL LOSS AND LAE DEVELOPMENT
Schedule of reconciliation of unpaid losses and settlement expenses (LAE)	The following table is a reconciliation of our unpaid losses and settlement expenses (LAE) for the years 2019, 2018 and 2017: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Unpaid losses and LAE at beginning of year: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ $ 1,461,348 ​ $ 1,271,503 ​ $ 1,139,337 ​ Ceded ​ (364,999) ​ (301,991) ​ (288,224) ​ Net ​ $ 1,096,349 ​ $ 969,512 ​ $ 851,113 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Increase (decrease) in incurred losses and LAE: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current accident year ​ $ 488,700 ​ $ 478,143 ​ $ 440,452 ​ Prior accident years ​ (75,284) ​ (49,950) ​ (38,868) ​ Total incurred ​ $ 413,416 ​ $ 428,193 ​ $ 401,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss and LAE payments for claims incurred: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current accident year ​ $ (80,055) ​ $ (76,050) ​ $ (73,392) ​ Prior accident year ​ (239,875) ​ (225,306) ​ (209,793) ​ Total paid ​ $ (319,930) ​ $ (301,356) ​ $ (283,185) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unpaid losses and LAE at end of year ​ $ 1,189,835 ​ $ 1,096,349 ​ $ 969,512 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unpaid losses and LAE at end of year: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ $ 1,574,352 ​ $ 1,461,348 ​ $ 1,271,503 ​ Ceded ​ (384,517) ​ (364,999) ​ (301,991) ​ Net ​ $ 1,189,835 ​ $ 1,096,349 ​ $ 969,512 ​
Schedule of incurred and paid claims development	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty - Primary Occurrence ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 87,875 $ 96,582 $ 93,589 $ 88,820 $ 85,034 $ 80,289 $ 78,685 $ 78,991 $ 80,216 $ 79,656 ​ $ 1,922 ​ 6,128 2011 ​ ​ ​ ​ 91,139 ​ 98,428 ​ 94,145 ​ 89,622 ​ 86,342 ​ 83,181 ​ 82,193 ​ 82,248 ​ 81,579 ​ ​ 2,546 ​ 5,862 2012 ​ ​ ​ ​ ​ ​ 91,807 ​ 78,406 ​ 65,893 ​ 61,072 ​ 59,028 ​ 59,488 ​ 60,328 ​ 60,465 ​ ​ 2,922 ​ 5,179 2013 ​ ​ ​ ​ ​ ​ ​ ​ 80,823 ​ 67,297 ​ 62,882 ​ 60,329 ​ 60,162 ​ 59,556 ​ 59,116 ​ ​ 4,917 ​ 4,307 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 88,092 ​ 79,497 ​ 71,592 ​ 67,237 ​ 66,389 ​ 66,702 ​ ​ 8,251 ​ 4,266 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 94,835 ​ 84,975 ​ 83,579 ​ 78,675 ​ 76,398 ​ ​ 14,891 ​ 4,362 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 101,950 ​ 96,753 ​ 90,611 ​ 85,449 ​ ​ 24,712 ​ 4,240 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 119,741 ​ 111,391 ​ 102,583 ​ ​ 46,557 ​ 4,336 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 141,513 ​ 130,281 ​ ​ 79,489 ​ 4,490 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 146,011 ​ ​ 119,051 ​ 4,193 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 888,240 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 2,587 $ 13,025 $ 29,312 $ 44,051 $ 55,992 $ 61,929 $ 66,399 $ 69,514 $ 73,318 $ 75,007 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 5,924 ​ 17,124 ​ 32,978 ​ 48,822 ​ 60,769 ​ 67,358 ​ 71,413 ​ 74,814 ​ 76,318 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 5,897 ​ 14,539 ​ 23,889 ​ 33,822 ​ 43,276 ​ 47,970 ​ 51,611 ​ 54,391 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 6,334 ​ 13,021 ​ 22,366 ​ 34,786 ​ 40,609 ​ 45,753 ​ 47,783 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 11,436 ​ 18,771 ​ 29,545 ​ 40,270 ​ 47,343 ​ 52,387 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,157 ​ 19,902 ​ 33,020 ​ 45,056 ​ 54,270 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,142 ​ 24,186 ​ 35,764 ​ 48,042 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 13,154 ​ 25,933 ​ 38,783 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 15,066 ​ 32,365 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 15,698 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 495,044 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 10,714 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 403,910 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 10.8 % 13.2 % 16.3 % 17.4 % 13.0 % 7.9 % 5.0 % 4.2 % 3.3 % 2.1 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty - Excess Occurrence ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 29,314 $ 24,244 $ 22,111 $ 18,932 $ 20,044 $ 22,044 $ 21,018 $ 20,530 $ 20,527 $ 20,579 ​ $ 315 ​ 503 2011 ​ ​ ​ ​ 26,272 ​ 17,148 ​ 17,443 ​ 18,641 ​ 19,160 ​ 20,959 ​ 21,295 ​ 22,032 ​ 21,825 ​ ​ 625 ​ 581 2012 ​ ​ ​ ​ ​ ​ 29,042 ​ 21,558 ​ 21,021 ​ 21,885 ​ 21,231 ​ 22,433 ​ 23,020 ​ 25,286 ​ ​ 1,016 ​ 858 2013 ​ ​ ​ ​ ​ ​ ​ ​ 39,984 ​ 34,824 ​ 26,857 ​ 25,425 ​ 25,599 ​ 24,922 ​ 25,496 ​ ​ 2,220 ​ 939 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 50,889 ​ 39,095 ​ 35,119 ​ 32,274 ​ 33,372 ​ 33,458 ​ ​ 6,322 ​ 887 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 53,672 ​ 50,857 ​ 47,392 ​ 42,840 ​ 43,328 ​ ​ 10,833 ​ 685 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 56,341 ​ 49,385 ​ 37,676 ​ 33,125 ​ ​ 18,457 ​ 624 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 62,863 ​ 55,868 ​ 48,363 ​ ​ 31,333 ​ 563 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 69,362 ​ 62,646 ​ ​ 51,501 ​ 452 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 88,078 ​ ​ 66,592 ​ 293 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 402,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 7 $ 6,002 $ 10,705 $ 13,282 $ 15,512 $ 17,302 $ 19,175 $ 19,256 $ 19,308 $ 19,390 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 2,169 ​ 5,145 ​ 6,981 ​ 8,793 ​ 10,772 ​ 16,494 ​ 17,769 ​ 20,214 ​ 21,036 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 1,315 ​ 3,573 ​ 8,843 ​ 15,380 ​ 16,879 ​ 17,747 ​ 19,310 ​ 21,993 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 1,060 ​ 5,701 ​ 10,967 ​ 14,545 ​ 16,967 ​ 17,956 ​ 18,524 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,899 ​ 4,006 ​ 11,002 ​ 18,852 ​ 22,541 ​ 23,376 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,048 ​ 10,127 ​ 19,571 ​ 23,184 ​ 28,756 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,068 ​ 3,396 ​ 7,441 ​ 10,054 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 17 ​ 5,679 ​ 9,275 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,506 ​ 5,823 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,213 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 162,440 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 16,409 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 256,153 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 4.2 % 13.2 % 16.9 % 14.3 % 9.9 % 8.9 % 5.8 % 7.4 % 2.0 % 0.4 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty - Claims Made ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 13,690 $ 15,556 $ 9,776 $ 10,429 $ 11,689 $ 10,581 $ 9,175 $ 9,024 $ 8,735 $ 8,680 ​ $ 160 ​ 502 2011 ​ ​ ​ ​ 17,416 ​ 17,454 ​ 12,260 ​ 10,619 ​ 8,510 ​ 7,720 ​ 7,852 ​ 11,506 ​ 14,031 ​ ​ 592 ​ 682 2012 ​ ​ ​ ​ ​ ​ 27,576 ​ 26,144 ​ 20,727 ​ 19,590 ​ 18,022 ​ 17,612 ​ 17,569 ​ 20,785 ​ ​ 1,781 ​ 803 2013 ​ ​ ​ ​ ​ ​ ​ ​ 40,095 ​ 41,488 ​ 44,054 ​ 40,288 ​ 38,473 ​ 37,959 ​ 38,352 ​ ​ 2,255 ​ 1,042 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 53,929 ​ 55,386 ​ 58,152 ​ 55,350 ​ 51,554 ​ 53,841 ​ ​ 4,391 ​ 1,305 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 55,006 ​ 47,831 ​ 42,206 ​ 39,906 ​ 39,653 ​ ​ 6,376 ​ 1,336 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 59,992 ​ 67,760 ​ 69,493 ​ 67,728 ​ ​ 16,541 ​ 1,506 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 60,572 ​ 62,450 ​ 62,714 ​ ​ 24,377 ​ 1,633 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 66,128 ​ 62,416 ​ ​ 37,809 ​ 1,381 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 62,918 ​ ​ 50,178 ​ 1,411 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 431,118 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 259 $ 1,548 $ 2,308 $ 3,626 $ 5,733 $ 5,749 $ 6,956 $ 8,485 $ 8,512 $ 8,515 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 330 ​ 1,949 ​ 4,508 ​ 5,947 ​ 5,637 ​ 6,209 ​ 6,835 ​ 7,132 ​ 7,239 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 433 ​ 4,086 ​ 6,898 ​ 9,218 ​ 10,968 ​ 14,378 ​ 15,621 ​ 16,450 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 792 ​ 7,073 ​ 18,425 ​ 26,121 ​ 29,678 ​ 32,789 ​ 34,535 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,705 ​ 9,775 ​ 27,923 ​ 35,755 ​ 40,080 ​ 44,127 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,215 ​ 10,738 ​ 16,774 ​ 20,920 ​ 28,795 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,060 ​ 14,558 ​ 27,465 ​ 39,370 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,455 ​ 11,350 ​ 22,728 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,964 ​ 11,965 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,839 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 215,563 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 2,399 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 217,954 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 3.1 % 16.2 % 19.5 % 14.2 % 11.3 % 7.3 % 7.2 % 7.9 % 0.5 % 0.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty - Transportation ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 27,239 $ 23,390 $ 24,912 $ 25,593 $ 23,981 $ 23,625 $ 23,701 $ 23,786 $ 23,776 $ 23,860 ​ $ 23 ​ 2,843 2011 ​ ​ ​ ​ 22,957 ​ 23,479 ​ 25,747 ​ 25,272 ​ 25,431 ​ 25,376 ​ 25,167 ​ 25,614 ​ 25,827 ​ ​ 41 ​ 2,469 2012 ​ ​ ​ ​ ​ ​ 21,452 ​ 22,203 ​ 22,924 ​ 23,511 ​ 23,689 ​ 23,620 ​ 23,305 ​ 23,731 ​ ​ 47 ​ 2,285 2013 ​ ​ ​ ​ ​ ​ ​ ​ 32,742 ​ 32,853 ​ 32,989 ​ 37,673 ​ 38,811 ​ 39,974 ​ 39,309 ​ ​ 140 ​ 2,853 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 38,361 ​ 33,015 ​ 36,452 ​ 38,590 ​ 40,202 ​ 40,508 ​ ​ 458 ​ 3,099 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 38,561 ​ 46,258 ​ 47,021 ​ 46,395 ​ 45,162 ​ ​ 1,574 ​ 3,183 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 50,430 ​ 53,519 ​ 54,105 ​ 52,277 ​ ​ 4,241 ​ 3,935 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 55,640 ​ 53,641 ​ 45,017 ​ ​ 7,476 ​ 3,625 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 57,597 ​ 54,592 ​ ​ 24,385 ​ 3,376 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 58,297 ​ ​ 17,932 ​ 3,082 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 408,580 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 6,296 $ 10,116 $ 15,475 $ 20,045 $ 21,792 $ 23,063 $ 23,488 $ 23,533 $ 23,556 $ 23,635 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 5,295 ​ 9,485 ​ 14,477 ​ 19,443 ​ 22,375 ​ 23,537 ​ 23,941 ​ 24,377 ​ 25,052 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 4,466 ​ 8,533 ​ 12,394 ​ 17,318 ​ 20,931 ​ 22,566 ​ 22,730 ​ 23,180 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 5,306 ​ 11,978 ​ 19,761 ​ 28,220 ​ 33,480 ​ 35,923 ​ 37,327 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,125 ​ 13,933 ​ 19,676 ​ 27,457 ​ 33,190 ​ 38,282 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6,984 ​ 20,709 ​ 29,554 ​ 37,222 ​ 39,339 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8,923 ​ 18,354 ​ 30,354 ​ 38,001 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,979 ​ 17,070 ​ 24,090 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6,980 ​ 12,827 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,148 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 268,881 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 252 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 139,951 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 17.2 % 18.1 % 18.8 % 18.8 % 11.0 % 7.1 % 1.9 % 1.3 % 1.4 % 0.3 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Property ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 63,194 $ 59,145 $ 55,427 $ 53,937 $ 54,153 $ 52,927 $ 52,964 $ 52,952 $ 52,903 $ 52,548 ​ $ 10 ​ 2,850 2011 ​ ​ ​ ​ 70,246 ​ 66,924 ​ 64,976 ​ 63,724 ​ 62,770 ​ 62,570 ​ 62,456 ​ 62,875 ​ 62,799 ​ ​ 65 ​ 3,028 2012 ​ ​ ​ ​ ​ ​ 85,485 ​ 80,155 ​ 79,181 ​ 77,569 ​ 79,175 ​ 78,125 ​ 78,161 ​ 78,002 ​ ​ 97 ​ 2,640 2013 ​ ​ ​ ​ ​ ​ ​ ​ 63,864 ​ 62,090 ​ 62,173 ​ 62,114 ​ 61,914 ​ 61,834 ​ 61,776 ​ ​ 183 ​ 2,995 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 56,587 ​ 49,441 ​ 48,801 ​ 48,761 ​ 49,217 ​ 49,444 ​ ​ 158 ​ 4,561 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 59,863 ​ 56,103 ​ 53,958 ​ 52,720 ​ 53,111 ​ ​ 403 ​ 4,075 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 62,900 ​ 55,594 ​ 55,384 ​ 55,930 ​ ​ 1,418 ​ 3,371 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 90,803 ​ 83,273 ​ 84,961 ​ ​ 5,861 ​ 2,883 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 89,091 ​ 83,457 ​ ​ 10,867 ​ 2,321 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 71,232 ​ ​ 27,090 ​ 2,098 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 653,260 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 25,274 $ 43,091 $ 47,743 $ 50,055 $ 52,729 $ 52,426 $ 52,719 $ 52,851 $ 52,855 $ 52,538 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 27,676 ​ 48,756 ​ 55,778 ​ 59,099 ​ 60,272 ​ 61,428 ​ 61,834 ​ 62,729 ​ 62,730 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 39,074 ​ 66,509 ​ 72,057 ​ 73,705 ​ 75,640 ​ 76,152 ​ 77,159 ​ 77,323 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 32,208 ​ 50,840 ​ 57,407 ​ 59,259 ​ 60,520 ​ 61,195 ​ 61,325 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 30,550 ​ 43,380 ​ 46,148 ​ 46,528 ​ 47,799 ​ 49,027 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 32,184 ​ 49,348 ​ 50,197 ​ 51,290 ​ 52,078 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 33,134 ​ 46,921 ​ 51,371 ​ 53,006 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 41,314 ​ 66,818 ​ 74,415 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 37,048 ​ 68,264 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 30,703 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 581,409 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 114 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 71,965 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 51.2 % 31.5 % 7.7 % 2.9 % 2.6 % 1.1 % 0.7 % 0.6 % 0.0 % (0.6) % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Surety ​ ​ ​ ​ ​ ​ ​ (in thousands, except number of claims) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance ​ ​ As of December 31, 2019 ​ ​ For the Years Ended December 31, ​ ​ ​ ​ Cumulative ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ Total IBNR ​ Claims 2010 ​ $ 13,961 $ 8,205 $ 6,630 $ 7,076 $ 6,810 $ 7,136 $ 7,645 $ 6,244 $ 6,580 $ 6,743 ​ $ 47 ​ 1,543 2011 ​ ​ ​ ​ 13,842 ​ 17,832 ​ 17,792 ​ 17,321 ​ 16,766 ​ 16,695 ​ 16,480 ​ 18,281 ​ 18,293 ​ ​ 35 ​ 1,679 2012 ​ ​ ​ ​ ​ ​ 17,114 ​ 11,452 ​ 8,667 ​ 8,180 ​ 7,867 ​ 7,471 ​ 7,099 ​ 7,082 ​ ​ 38 ​ 1,474 2013 ​ ​ ​ ​ ​ ​ ​ ​ 16,080 ​ 7,516 ​ 6,170 ​ 5,399 ​ 5,271 ​ 5,231 ​ 5,209 ​ ​ 65 ​ 1,406 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 16,450 ​ 8,106 ​ 5,225 ​ 4,427 ​ 4,267 ​ 4,319 ​ ​ 67 ​ 1,346 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 16,958 ​ 12,957 ​ 11,113 ​ 10,456 ​ 9,792 ​ ​ 384 ​ 1,217 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 18,928 ​ 11,062 ​ 9,351 ​ 8,895 ​ ​ 742 ​ 1,359 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 16,127 ​ 8,641 ​ 8,798 ​ ​ 1,469 ​ 1,645 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 16,765 ​ 7,227 ​ ​ 3,965 ​ 1,157 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14,785 ​ ​ 14,035 ​ 607 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ 91,143 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Years Ended December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AY ​ ​ 2010* ​ 2011* ​ 2012* ​ 2013* ​ 2014* ​ 2015* ​ 2016* ​ 2017* ​ 2018* ​ 2019 ​ ​ ​ ​ ​ 2010 ​ $ 1,724 $ 3,205 $ 5,702 $ 7,092 $ 7,151 $ 7,285 $ 7,822 $ 6,663 $ 6,637 $ 6,733 ​ ​ ​ ​ ​ 2011 ​ ​ ​ ​ 8,160 ​ 16,932 ​ 17,151 ​ 17,403 ​ 17,212 ​ 17,086 ​ 17,086 ​ 17,013 ​ 18,251 ​ ​ ​ ​ ​ 2012 ​ ​ ​ ​ ​ ​ 1,883 ​ 6,680 ​ 6,726 ​ 7,416 ​ 7,536 ​ 7,406 ​ 7,065 ​ 6,996 ​ ​ ​ ​ ​ 2013 ​ ​ ​ ​ ​ ​ ​ ​ 1,116 ​ 2,856 ​ 4,701 ​ 4,911 ​ 5,098 ​ 5,150 ​ 5,128 ​ ​ ​ ​ ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 722 ​ 4,283 ​ 4,166 ​ 4,059 ​ 4,131 ​ 4,234 ​ ​ ​ ​ ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 3,192 ​ 6,719 ​ 7,695 ​ 9,436 ​ 9,183 ​ ​ ​ ​ ​ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 3,087 ​ 5,817 ​ 6,299 ​ 7,640 ​ ​ ​ ​ ​ 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 979 ​ 2,862 ​ 7,062 ​ ​ ​ ​ ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,835 ​ 2,588 ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 336 ​ ​ ​ ​ ​ ​ ​ * Presented as unaudited required supplementary information. ​ ​ ​ ​ ​ ​ ​ Total $ 68,151 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ All outstanding liabilities before 2010, net of reinsurance ​ 1,996 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities for losses and loss adjustment expenses, net of reinsurance $ 24,988 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance* ​ ​ ​ ​ ​ Years ​ ​ 1 ​ 2 ​ 3 ​ 4 ​ 5 ​ 6 ​ 7 ​ 8 ​ 9 ​ 10 ​ ​ ​ ​ ​ ​ ​ ​ 24.1 % 39.1 % 16.8 % 9.4 % 0.7 % 0.6 % 0.7 % (6.2) % 3.2 % 1.4 % ​ ​ ​ ​
Schedule of reconciliation of the net incurred and paid loss development tables to the liability for unpaid losses and settlement expenses in the consolidated balance sheet	​ ​ ​ ​ ​ ​ ​ ​ Reconciliation of Incurred and Paid Loss Development to the Liability for Unpaid Losses and Settlement Expenses (in thousands) ​ December 31, 2019 ​ December 31, 2018 Net outstanding liabilities: ​ ​ ​ ​ ​ ​ Casualty - Primary Occurrence ​ $ 403,910 ​ $ 372,450 Casualty - Excess Occurrence ​ ​ 256,153 ​ ​ 209,683 Casualty - Claims Made ​ ​ 217,954 ​ ​ 204,501 Casualty - Transportation ​ ​ 139,951 ​ ​ 133,558 Property ​ ​ 71,965 ​ ​ 77,238 Surety ​ ​ 24,988 ​ ​ 28,237 Unallocated loss adjustment expenses ​ ​ 52,275 ​ ​ 50,891 Allowance for uncollectible reinsurance balances recoverable on unpaid losses and settlement expenses ​ ​ 9,402 ​ ​ 9,793 Other ​ ​ 13,237 ​ ​ 9,998 Liabilities for unpaid loss and settlement expenses, net of reinsurance ​ $ 1,189,835 ​ $ 1,096,349 ​ ​ ​ ​ ​ ​ ​ Reinsurance recoverable on unpaid claims: ​ ​ ​ ​ ​ ​ Casualty - Primary Occurrence ​ $ 31,122 ​ $ 34,742 Casualty - Excess Occurrence ​ ​ 98,518 ​ ​ 81,072 Casualty - Claims Made ​ ​ 176,936 ​ ​ 144,921 Casualty - Transportation ​ ​ 53,724 ​ ​ 50,748 Property ​ ​ 21,438 ​ ​ 50,495 Surety ​ ​ 11,199 ​ ​ 11,834 Allowance for uncollectible reinsurance balances recoverable on unpaid losses and settlement expenses ​ ​ (9,402) ​ ​ (9,793) Other ​ ​ 982 ​ ​ 980 Total reinsurance balances recoverable on unpaid losses and settlement expenses ​ $ 384,517 ​ $ 364,999 ​ ​ ​ ​ ​ ​ ​ Total gross liability for unpaid loss and settlement expenses ​ $ 1,574,352 ​ $ 1,461,348
Schedule of prior accident years' loss reserve development by segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (FAVORABLE)/UNFAVORABLE RESERVE DEVELOPMENT BY SEGMENT ​ (in thousands) 2019 2018 2017 ​ Casualty ​ $ (62,497) ​ $ (33,252) ​ $ (17,462) ​ Property ​ (4,461) ​ (10,813) ​ (12,134) ​ Surety ​ (8,326) ​ (5,885) ​ (9,272) ​ Total ​ $ (75,284) ​ $ (49,950) ​ $ (38,868) ​
Schedule of paid and unpaid environmental, asbestos and mass tort claims data (including incurred but not reported losses)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Loss and LAE Payments (Cumulative): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ $ 137,485 ​ $ 136,043 ​ $ 132,883 ​ Ceded ​ (68,849) ​ (68,638) ​ (67,507) ​ Net ​ $ 68,636 ​ $ 67,405 ​ $ 65,376 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unpaid Losses and LAE at End of Year: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ $ 22,616 ​ $ 24,262 ​ $ 28,042 ​ Ceded ​ (5,149) ​ (5,373) ​ (5,715) ​ Net ​ $ 17,467 ​ $ 18,889 ​ $ 22,327 ​

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2019
INCOME TAXES
Schedule of deferred tax assets and deferred tax liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Tax discounting of unpaid losses and settlement expenses ​ $ 19,143 ​ $ 18,327 ​ Unearned premium offset ​ 18,755 ​ 17,864 ​ Deferred compensation ​ 2,981 ​ 2,700 ​ Stock option expense ​ 2,728 ​ 2,702 ​ Lease liability ​ 5,140 ​ — ​ Other ​ 275 ​ 616 ​ Deferred tax assets before allowance ​ $ 49,022 ​ $ 42,209 ​ Less valuation allowance ​ — ​ — ​ Total deferred tax assets ​ $ 49,022 ​ $ 42,209 ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Net unrealized appreciation of securities ​ $ 56,532 ​ $ 22,177 ​ Deferred policy acquisition costs ​ 17,859 ​ 17,836 ​ Lease asset ​ ​ 4,690 ​ ​ — ​ Discounting of unpaid losses and settlement expenses - Tax Cuts and Jobs Act (TCJA) implementation offset ​ ​ 3,817 ​ ​ 5,203 ​ Book/tax depreciation ​ 3,008 ​ 3,133 ​ Intangible assets ​ 1,634 ​ 1,711 ​ Undistributed earnings of unconsolidated investees ​ 17,673 ​ 15,811 ​ Other ​ 536 ​ 576 ​ Total deferred tax liabilities ​ $ 105,749 ​ $ 66,447 ​ Net deferred tax liability ​ $ (56,727) ​ $ (24,238) ​
Schedule of reconciliation of income tax expense attributable to income from operations with amounts computed by applying the U.S. federal tax rate to pretax income from continuing operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Provision for income taxes at the statutory federal tax rates ​ $ 48,874 ​ 21.0 % ​ $ 14,192 ​ 21.0 % ​ $ 29,606 ​ 35.0 % ​ Increase (reduction) in taxes resulting from: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Enactment of TCJA ​ ​ — ​ — % ​ ​ (2,268) ​ (3.4) % ​ ​ (32,821) ​ (38.8) % ​ Excess tax benefit on share-based compensation ​ ​ (3,958) ​ (1.7) % ​ ​ (4,533) ​ (6.7) % ​ ​ (5,798) ​ (6.9) % ​ Dividends received deduction ​ (823) ​ (0.4) % ​ (775) ​ (1.1) % ​ (2,025) ​ (2.4) % ​ ESOP dividends paid deduction ​ (1,122) ​ (0.5) % ​ (1,184) ​ (1.8) % ​ (2,905) ​ (3.4) % ​ Tax-exempt interest income ​ (1,238) ​ (0.5) % ​ (1,795) ​ (2.7) % ​ (4,671) ​ (5.5) % ​ Unconsolidated investee dividends ​ (1,802) ​ (0.8) % ​ — ​ — % ​ (1,351) ​ (1.6) % ​ Nondeductible expenses ​ ​ 1,649 ​ 0.7 % ​ ​ 389 ​ 0.6 % ​ ​ 276 ​ 0.3 % ​ Other items, net ​ (488) ​ (0.1) % ​ (624) ​ (0.9) % ​ (750) ​ (0.9) % ​ Total ​ $ 41,092    ​ 17.7 % ​ $ 3,402    ​ 5.0 % ​ $ (20,439)    ​ (24.2) % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

EMPLOYEE BENEFITS (Tables)

EMPLOYEE BENEFITS (Tables)	12 Months Ended
	Dec. 31, 2019
EMPLOYEE BENEFITS
Schedule of stock option activity	The following tables summarize option activity in 2019, 2018 and 2017: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Weighted ​ Average ​ Aggregate ​ ​ Number of ​ Average ​ Remaining ​ Intrinsic ​ ​ Options ​ Exercise ​ Contractual ​ Value ​ ​ Outstanding ​ Price ​ Life ​ (in 000’s) Outstanding options at January 1, 2019 ​ 1,964,880 ​ $ 54.24 ​ ​ ​ ​ ​ ​ Options granted ​ 356,900 ​ $ 82.63 ​ ​ ​ ​ ​ ​ Options exercised ​ (533,940) ​ $ 45.96 ​ ​ ​ $ 20,033 ​ Options canceled/forfeited ​ (120,550) ​ $ 60.48 ​ ​ ​ ​ ​ ​ Outstanding options at December 31, 2019 ​ 1,667,290 ​ $ 62.52 5.20 ​ $ 46,051 ​ Exercisable options at December 31, 2019 ​ 642,365 ​ $ 53.93 3.80 ​ $ 23,197 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Weighted ​ Average ​ Aggregate ​ ​ Number of ​ Average ​ Remaining ​ Intrinsic ​ ​ Options ​ Exercise ​ Contractual ​ Value ​ ​ Outstanding ​ Price ​ Life ​ (in 000’s) Outstanding options at January 1, 2018 2,257,015 ​ $ 46.80 ​ ​ ​ ​ ​ ​ Options granted 432,000 ​ $ 64.91 ​ ​ ​ ​ ​ ​ Options exercised (705,785) ​ $ 36.81 ​ ​ ​ $ 24,304 ​ Options canceled/forfeited (18,350) ​ $ 60.84 ​ ​ ​ ​ ​ ​ Outstanding options at December 31, 2018 1,964,880 ​ $ 54.24 5.25 ​ $ 29,317 ​ Exercisable options at December 31, 2018 724,730 ​ $ 46.62 3.79 ​ $ 16,212 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average ​ Aggregate ​ ​ Number of ​ Average Remaining ​ Intrinsic ​ ​ Options ​ Exercise Contractual ​ Value ​ ​ Outstanding Price Life (in 000’s) Outstanding options at January 1, 2017 2,207,110 ​ $ 40.90 ​ ​ ​ ​ ​ ​ Options granted 482,375 ​ $ 57.12 ​ ​ ​ ​ ​ ​ Options exercised (390,870) ​ $ 26.07 ​ ​ ​ $ 12,779 ​ Options canceled/forfeited (41,600) ​ $ 48.30 ​ ​ ​ ​ ​ ​ Outstanding options at December 31, 2017 2,257,015 ​ $ 46.80 4.88 ​ $ 32,620 ​ Exercisable options at December 31, 2017 975,055 ​ $ 38.66 3.25 ​ $ 21,780 ​
Schedule of stock option assumptions for fair value estimate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 2018 2017 Weighted-average fair value of grants ​ $ 13.49 ​ $ 10.58 ​ $ 8.00 ​ Risk-free interest rates ​ 2.26 % 2.72 % 1.90 % Dividend yield ​ 2.69 % 2.98 % 3.60 % Expected volatility ​ 22.71 % 22.87 % 22.95 % Expected option life ​ 4.96 years 5.07 years 5.05 years

STATUTORY INFORMATION AND DIV_2

STATUTORY INFORMATION AND DIVIDEND RESTRICTIONS (Tables)	12 Months Ended
	Dec. 31, 2019
STATUTORY INFORMATION AND DIVIDEND RESTRICTIONS
Schedule of selected information for insurance subsidiaries	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 Consolidated net income, statutory basis ​ $ 129,625 ​ $ 135,791 ​ $ 72,889 ​ Consolidated surplus, statutory basis ​ $ 1,029,671 ​ $ 829,775 ​ $ 864,554 ​

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2019
Leases
Schedule of components of lease expense and other lease information	​ ​ ​ ​ ​ ​ (in thousands) ​ 2019 Operating lease cost ​ $ 5,772 ​ ​ ​ ​ ​ ​ Cash paid for amounts included in measurement of lease liabilities ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 5,711 ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for new operating lease liabilities ​ $ 1,388 ​ ​ ​ ​ ​ ​ Reduction to right-of-use assets resulting from reduction to lease liabilities ​ $ 1,279 ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2019 Operating lease right-of-use assets ​ $ 22,335 ​ ​ ​ ​ ​ ​ Operating lease liabilities ​ $ 24,475 ​ ​ ​ ​ ​ ​ Weighted-average remaining lease term - operating leases ​ ​ 4.69 years ​ ​ ​ ​ ​ Weighted-average discount rate - operating leases ​ ​ 2.33 %
Schedule of future minimum lease payments under non-cancellable leases	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ 2019 ​ (in thousands) ​ 2018 2020 ​ $ 5,983 ​ 2019 ​ $ 5,911 2021 ​ ​ 5,968 ​ 2020 ​ ​ 6,019 2022 ​ ​ 5,904 ​ 2021 ​ ​ 5,924 2023 ​ ​ 4,386 ​ 2022 ​ ​ 5,884 2024 ​ ​ 2,334 ​ 2023 ​ ​ 4,459 Thereafter ​ ​ 1,366 ​ Thereafter ​ ​ 3,968 Total future minimum lease payments ​ $ 25,941 ​ Total future minimum lease payments ​ $ 32,165 Less imputed interest ​ ​ (1,466) ​ ​ ​ ​ ​ Total operating lease liability ​ $ 24,475 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

OPERATING SEGMENT INFORMATION (

OPERATING SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2019
OPERATING SEGMENT INFORMATION
Schedule of revenues and net earnings by segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ REVENUES ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Casualty ​ $ 558,458 ​ $ 523,472 ​ $ 478,603 ​ Property ​ 164,022 ​ 149,261 ​ 138,346 ​ Surety ​ 116,631 ​ 118,633 ​ 120,988 ​ Net premiums earned ​ $ 839,111 ​ $ 791,366 ​ $ 737,937 ​ Net investment income ​ 68,870 ​ 62,085 ​ 54,876 ​ Net realized gains ​ 17,520 ​ 63,407 ​ 4,411 ​ Net unrealized gains (losses) on equity securities ​ ​ 78,090 ​ ​ (98,735) ​ ​ — ​ Total ​ $ 1,003,591 ​ $ 818,123 ​ $ 797,224 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ INSURANCE EXPENSES ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Loss and settlement expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty ​ $ 330,156 ​ $ 329,763 ​ $ 305,679 ​ Property ​ 73,614 ​ 83,822 ​ 85,027 ​ Surety ​ 9,646 ​ 14,608 ​ 10,878 ​ Total loss and settlement expenses ​ $ 413,416 ​ $ 428,193 ​ $ 401,584 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Policy acquisition costs: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty ​ $ 166,499 ​ $ 151,007 ​ $ 136,135 ​ Property ​ 55,986 ​ 51,830 ​ 51,070 ​ Surety ​ 66,212 ​ 64,901 ​ 65,310 ​ Total policy acquisition costs ​ $ 288,697 ​ $ 267,738 ​ $ 252,515 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other insurance expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Casualty ​ $ 41,202 ​ $ 31,562 ​ $ 32,885 ​ Property ​ 16,279 ​ 12,725 ​ 14,108 ​ Surety ​ 11,949 ​ 9,516 ​ 10,001 ​ Total other insurance expenses ​ $ 69,430 ​ $ 53,803 ​ $ 56,994 ​ Total ​ $ 771,543 ​ $ 749,734 ​ $ 711,093 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NET EARNINGS (LOSSES) ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2019 2018 2017 ​ Casualty ​ $ 20,601 ​ $ 11,140 ​ $ 3,904 ​ Property ​ 18,143 ​ 884 ​ (11,859) ​ Surety ​ 28,824 ​ 29,608 ​ 34,799 ​ Net underwriting income ​ $ 67,568 ​ $ 41,632 ​ $ 26,844 ​ Net investment income ​ 68,870 ​ 62,085 ​ 54,876 ​ Net realized gains ​ 17,520 ​ 63,407 ​ 4,411 ​ Net unrealized gains (losses) on equity securities ​ ​ 78,090 ​ ​ (98,735) ​ ​ — ​ General corporate expense and interest on debt ​ (20,274) ​ (16,864) ​ (18,766) ​ Equity in earnings of unconsolidated investees ​ 20,960 ​ 16,056 ​ 17,224 ​ Total earnings before incomes taxes ​ $ 232,734 ​ $ 67,581 ​ $ 84,589 ​ Income tax expense (benefit) ​ $ 41,092 ​ $ 3,402 ​ $ (20,439) ​ Total ​ $ 191,642 ​ $ 64,179 ​ $ 105,028 ​
Schedule of net premiums earned by major product type	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NET PREMIUMS EARNED ​ Year ended December 31, (in thousands) 2019 2018 2017 CASUALTY ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial excess and personal umbrella ​ $ 140,483 ​ $ 124,350 ​ $ 115,543 ​ General liability ​ 98,880 ​ 93,928 ​ 90,283 ​ Commercial transportation ​ 83,213 ​ 81,053 ​ 78,061 ​ Professional services ​ 81,329 ​ 79,951 ​ 78,508 ​ Small commercial ​ 55,701 ​ 51,519 ​ 49,601 ​ Executive products ​ 27,088 ​ 21,326 ​ 18,086 ​ Other casualty ​ 71,764 ​ 71,345 ​ 48,521 ​ Total ​ $ 558,458 ​ $ 523,472 ​ $ 478,603 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ PROPERTY ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Marine ​ $ 74,887 ​ $ 59,795 ​ $ 50,931 ​ Commercial property ​ ​ 68,310 ​ ​ 71,501 ​ ​ 63,117 ​ Specialty personal ​ ​ 19,316 ​ ​ 16,901 ​ ​ 20,793 ​ Other property ​ 1,509 ​ 1,064 ​ 3,505 ​ Total ​ $ 164,022 ​ $ 149,261 ​ $ 138,346 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SURETY ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Miscellaneous ​ $ 44,721 ​ $ 46,968 ​ $ 47,237 ​ Commercial ​ 43,553 ​ 43,469 ​ 45,178 ​ Contract ​ 28,357 ​ 28,196 ​ 28,573 ​ Total ​ $ 116,631 ​ $ 118,633 ​ $ 120,988 ​ Grand total ​ $ 839,111 ​ $ 791,366 ​ $ 737,937 ​

UNAUDITED INTERIM FINANCIAL I_2

UNAUDITED INTERIM FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2019
UNAUDITED INTERIM FINANCIAL INFORMATION
Schedule of selected quarterly information	Select unaudited quarterly information is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands, except per share data) First Second Third Fourth Year ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net premiums earned ​ $ 204,689 ​ $ 207,541 ​ $ 211,255 ​ $ 215,626 ​ $ 839,111 ​ Net investment income ​ 16,565 ​ 16,998 ​ 17,532 ​ 17,775 ​ 68,870 ​ Net realized gains ​ 9,068 ​ 4,764 ​ 3,211 ​ 477 ​ 17,520 ​ Net unrealized gains (losses) on equity securities ​ ​ 33,498 ​ ​ 8,810 ​ ​ 4,906 ​ ​ 30,876 ​ ​ 78,090 ​ Earnings (losses) before income taxes ​ 81,741 ​ 48,828 ​ 38,947 ​ 63,218 ​ 232,734 ​ Net earnings (loss) ​ 65,473 ​ 40,467 ​ 32,324 ​ 53,378 ​ 191,642 ​ Basic earnings per share(1) ​ $ 1.47 ​ $ 0.91 ​ $ 0.72 ​ $ 1.19 ​ $ 4.28 ​ Diluted earnings per share(1) ​ $ 1.46 ​ $ 0.89 ​ $ 0.71 ​ $ 1.18 ​ $ 4.23 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net premiums earned ​ $ 190,027 ​ $ 196,522 ​ $ 200,815 ​ $ 204,002 ​ $ 791,366 ​ Net investment income ​ 14,232 ​ 14,577 ​ 16,314 ​ 16,962 ​ 62,085 ​ Net realized gains ​ 8,404 ​ 20,849 ​ 18,647 ​ 15,507 ​ 63,407 ​ Net unrealized gains (losses) on equity securities ​ ​ (26,772) ​ ​ (12,611) ​ ​ 4,848 ​ ​ (64,200) ​ ​ (98,735) ​ Earnings (losses) before income taxes ​ 14,378 ​ 39,562 ​ 46,349 ​ (32,708) ​ 67,581 ​ Net earnings (loss) ​ 12,216 ​ 33,251 ​ 39,372 ​ (20,660) ​ 64,179 ​ Basic earnings per share(1) ​ $ 0.28 ​ $ 0.75 ​ $ 0.89 ​ $ (0.46) ​ $ 1.45 ​ Diluted earnings per share(1) ​ $ 0.27 ​ $ 0.74 ​ $ 0.88 ​ $ (0.46) ​ $ 1.43 ​ (1) Since the weighted-average shares for the quarters are calculated independently of the weighted-average shares for the year, quarterly earnings per share may not total to annual earnings per share.

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Description of Business (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019companystate$ / shares	Dec. 31, 2018USD ($)$ / shares	Dec. 31, 2017$ / shares
DESCRIPTION OF BUSINESS
Number of insurance companies through which the entity conducts operations | company	3
Common Stock, Par or Stated Value Per Share | $ / shares	$ 0.01	$ 0.01	$ 1
Reclassification From Common Stock		$ 66,400
Reclassification Into Paid In Capital		66,400
RLI Ins.
DESCRIPTION OF BUSINESS
Number of states in which entity operates | state	50
Mt. Hawley Insurance Company
DESCRIPTION OF BUSINESS
Number of states in which entity operates | state	50
Contractors Bonding and Insurance Company
DESCRIPTION OF BUSINESS
Number of states in which entity operates | state	50
Common stock
DESCRIPTION OF BUSINESS
Reclassification due to change in par value		(66,409)
Paid-in Capital
DESCRIPTION OF BUSINESS
Reclassification due to change in par value		$ 66,409

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounting Standards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Percentage Of Fixed Income Portfolio Rated A Or Better	85.00%
Operating Lease, Right-of-Use Asset	$ 22,335,000
Operating Lease Liabilities	24,475,000
Allocated Share-based Compensation Expense	4,500,000	$ 4,500,000	$ 4,400,000
Accounting Standards Update 2016-02
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets				$ 0
Outside director | Restricted Stock Units (RSUs)
Allocated Share-based Compensation Expense	$ 600,000

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2019
Equipment | Minimum
PROPERTY AND EQUIPMENT
Useful life	3 years
Equipment | Maximum
PROPERTY AND EQUIPMENT
Useful life	10 years
Buildings and improvements | Maximum
PROPERTY AND EQUIPMENT
Useful life	30 years

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Investment in Unconsolidated Investees (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)item	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
INVESTMENT IN UNCONSOLIDATED INVESTEES:
Investment amount	$ 103,836,000				$ 94,967,000				$ 103,836,000	$ 94,967,000
Investee earnings recorded in income									20,960,000	16,056,000	$ 17,224,000
Reinsurance assumed									25,047,000	48,303,000	37,159,000
Net premiums earned	$ 215,626,000	$ 211,255,000	$ 207,541,000	$ 204,689,000	204,002,000	$ 200,815,000	$ 196,522,000	$ 190,027,000	839,111,000	791,366,000	737,937,000
Additional summarized financial information for investee
Dividends received									$ 13,200,000	9,900,000	0
Maui Jim Inc.
INVESTMENT IN UNCONSOLIDATED INVESTEES:
Equity ownership interest (as a percent)	40.00%								40.00%
Prime Holdings Insurance Services, Inc. (Prime)
INVESTMENT IN UNCONSOLIDATED INVESTEES:
Equity ownership interest (as a percent)	23.00%								23.00%
Maui Jim Inc.
INVESTMENT IN UNCONSOLIDATED INVESTEES:
Investment amount	$ 79,600,000				79,500,000				$ 79,600,000	79,500,000
Investee earnings recorded in income									13,600,000	12,500,000	14,400,000
Total investee net income									$ 35,600,000	30,300,000	34,400,000
Equity ownership interest (as a percent)	40.00%								40.00%
Additional summarized financial information for investee
Total assets	$ 282,200,000				265,600,000				$ 282,200,000	265,600,000
Total liabilities	104,800,000				90,400,000				104,800,000	90,400,000
Total equity	177,400,000				175,200,000				177,400,000	175,200,000
Undistributed earnings included in retained earnings	69,300,000								69,300,000
Dividends received									13,200,000	9,900,000	0
Prime Holdings Insurance Services, Inc. (Prime)
INVESTMENT IN UNCONSOLIDATED INVESTEES:
Investment amount	$ 24,200,000				$ 15,400,000				24,200,000	15,400,000
Investee earnings recorded in income									$ 7,400,000	3,600,000	2,800,000
Number of insurance carriers Company writes through | item									2
Equity ownership interest (as a percent)	23.00%								23.00%
Reinsurance assumed									$ 13,100,000	41,100,000	29,600,000
Net premiums earned									$ 28,700,000	$ 34,200,000	$ 21,000,000

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets
Goodwill	$ 46,062,000	$ 46,062,000
State insurance licenses	7,500,000	7,500,000
Definite-lived intangibles, net of accumulated amortization of $3,470 at 12/31/19 and $3,062 at 12/31/18	565,000	972,000
Accumulated amortization of definite-lived intangibles	3,470,000	3,062,000
Total intangibles	8,065,000	8,472,000
Goodwill and intangibles	54,127,000	54,534,000
Goodwill and Intangible Asset Impairment	0
Amortization of intangible assets	400,000	400,000	$ 700,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	400,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	100,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	100,000
Energy Surety
Goodwill and Intangible Assets
Goodwill	25,706,000	25,706,000
Miscellaneous and Contract Surety
Goodwill and Intangible Assets
Goodwill	15,110,000	15,110,000
Small commercial
Goodwill and Intangible Assets
Goodwill	$ 5,246,000	5,246,000
Medical professional liability
Goodwill and Intangible Assets
Goodwill		0
Casualty segment | Medical professional liability
Goodwill and Intangible Assets
Goodwill and Intangible Asset Impairment		4,400,000	3,400,000
Goodwill, Impairment Loss		3,600,000	1,600,000
Impairment of Intangible Assets, Finite-lived		$ 800,000	$ 1,800,000

SUMMARY OF SIGNIFICANT ACCOUN_9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic EPS, Income (Numerator)
Income available to common shareholders									$ 191,642	$ 64,179	$ 105,028
Diluted EPS, Income (Numerator)
Income available to common shareholders									$ 191,642	$ 64,179	$ 105,028
Basic EPS, Weighted Average Shares (Denominator)
Number of shares outstanding									44,734	44,358	44,033
Effect of Dilutive Securities, Shares (Denominator)
Stock options (in shares)									523	477	467
Diluted EPS, Weighted Average Shares (Denominator)
Number of shares outstanding									45,257	44,835	44,500
Basic EPS, Per Share Amount
Basic net earnings per share (in dollars per share)	$ 1.19	$ 0.72	$ 0.91	$ 1.47	$ (0.46)	$ 0.89	$ 0.75	$ 0.28	$ 4.28	$ 1.45	$ 2.39
Diluted EPS, Per Share Amount
Diluted earnings per share (in dollars per share)	$ 1.18	$ 0.71	$ 0.89	$ 1.46	$ (0.46)	$ 0.88	$ 0.74	$ 0.27	$ 4.23	$ 1.43	$ 2.36

SUMMARY OF SIGNIFICANT ACCOU_10

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Changes in Accumulated Other Comprehensive Earnings (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
COMPREHENSIVE EARNINGS
Tax rate used (as a percent)									21.00%	21.00%	35.00%
Other comprehensive income (loss), tax									$ 17,800,000	$ (9,000,000)	$ 19,000,000
Changes in the balance of each component of accumulated other comprehensive earnings
Beginning balance				$ (14,572,000)					(14,572,000)
Cumulative-effect adjustment from ASU 2016-01					$ 86,000					86,000
Net current-period other comprehensive earnings (loss)									67,045,000	(33,997,000)	35,309,000
Reclassification of stranded tax effect per ASU 2018-02										3,700,000
Ending balance	$ 52,473,000				(14,572,000)				52,473,000	(14,572,000)
Reclassification Adjustment Out of Accumulated Other Comprehensive Income
Net realized gains									17,520,000	63,624,000	6,970,000
Other-than-temporary-impairment (OTTI) losses on investments									0	(217,000)	(2,559,000)
Earnings before income taxes	63,218,000	$ 38,947,000	$ 48,828,000	81,741,000	(32,708,000)	$ 46,349,000	$ 39,562,000	$ 14,378,000	232,734,000	67,581,000	84,589,000
Income tax expense									(41,092,000)	(3,402,000)	20,439,000
Net earnings	53,378,000	$ 32,324,000	$ 40,467,000	65,473,000	(20,660,000)	$ 39,372,000	$ 33,251,000	12,216,000	191,642,000	64,179,000	105,028,000
Unrealized Gains and Losses on Available-for-Sale Securities
Changes in the balance of each component of accumulated other comprehensive earnings
Beginning balance				$ (14,572,000)				$ 157,919,000	(14,572,000)	157,919,000	122,610,000
Adjusted beginning balance	(14,572,000)				15,700,000				(14,572,000)	15,700,000	122,610,000
Other comprehensive earnings before reclassifications									69,560,000	(35,763,000)	40,887,000
Amounts reclassified from accumulated other comprehensive earnings									(2,515,000)	1,766,000	(5,578,000)
Net current-period other comprehensive earnings (loss)									67,045,000	(33,997,000)	35,309,000
Reclassification of stranded tax effect per ASU 2018-02										3,725,000
Ending balance	$ 52,473,000				(14,572,000)				52,473,000	(14,572,000)	157,919,000
Unrealized Gains and Losses on Available-for-Sale Securities | ASU 2016-01
Changes in the balance of each component of accumulated other comprehensive earnings
Cumulative-effect adjustment from ASU 2016-01					$ (142,219,000)					(142,219,000)		$ (142,200,000)
Reclassifications out of accumulated other comprehensive earnings
Reclassification Adjustment Out of Accumulated Other Comprehensive Income
Net realized gains									3,184,000	(2,018,000)	11,141,000
Other-than-temporary-impairment (OTTI) losses on investments										(217,000)	(2,559,000)
Earnings before income taxes									3,184,000	(2,235,000)	8,582,000
Income tax expense									(669,000)	469,000	(3,004,000)
Net earnings									$ 2,515,000	$ (1,766,000)	$ 5,578,000

SUMMARY OF SIGNIFICANT ACCOU_11

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Insurance Risk (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Unpaid losses and settlement expenses	$ 1,574,352	$ 1,461,348	$ 1,271,503	$ 1,139,337

SUMMARY OF SIGNIFICANT ACCOU_12

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Catastrophe Exposures (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Earthquake
Catastrophe Exposures
First-dollar retention	$ 25
California earthquake
Catastrophe Exposures
Catastrophe reinsurance	400
First-dollar retention	25
Non-California earthquake
Catastrophe Exposures
Catastrophe reinsurance	425
First-dollar retention	25
Other perils
Catastrophe Exposures
Catastrophe reinsurance	275
First-dollar retention	$ 25

INVESTMENTS - Net Investment In

INVESTMENTS - Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net investment income
Gross investment income									$ 73,988	$ 66,614	$ 59,794
Less investment expenses									(5,118)	(4,529)	(4,918)
Net Investment Income	$ 17,775	$ 17,532	$ 16,998	$ 16,565	$ 16,962	$ 16,314	$ 14,577	$ 14,232	68,870	62,085	54,876
Debt securities
Net investment income
Gross investment income									60,364	54,491	48,343
Equity securities
Net investment income
Gross investment income									9,950	9,814	10,506
Cash and Short-term Investments
Net investment income
Gross investment income									$ 3,674	$ 2,309	$ 945

INVESTMENTS - Realized and Unre

INVESTMENTS - Realized and Unrealized Gains (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INVESTMENTS
Net realized gains (losses), excluding OTTI									$ 17,520,000	$ 63,624,000	$ 6,970,000
OTTI									0	(217,000)	(2,559,000)
Net realized gains	$ 477,000	$ 3,211,000	$ 4,764,000	$ 9,068,000	$ 15,507,000	$ 18,647,000	$ 20,849,000	$ 8,404,000	17,520,000	63,407,000	4,411,000
Net changes in unrealized gains (losses) on investments:									84,867,000	(43,035,000)	54,323,000
Net unrealized gains (losses) on equity securities	$ 30,876,000	$ 4,906,000	$ 8,810,000	$ 33,498,000	$ (64,200,000)	$ 4,848,000	$ (12,611,000)	$ (26,772,000)	78,090,000	(98,735,000)
Net realized gains (losses) and changes in unrealized gains (losses) on investments									180,477,000	(78,363,000)	58,734,000
Total Net Unrealized Gains (Losses)									163,000,000
Debt securities | Available for sale securities
INVESTMENTS
Net realized gains (losses), excluding OTTI									3,184,000	(2,018,000)	859,000
Net changes in unrealized gains (losses) on investments:									83,758,000	(41,778,000)	16,846,000
Equity securities
INVESTMENTS
Net realized gains (losses), excluding OTTI									14,445,000	69,868,000	10,282,000
Net changes in unrealized gains (losses) on investments:											36,844,000
Net unrealized gains (losses) on equity securities									78,389,000	(98,380,000)
Other
INVESTMENTS
Net realized gains (losses), excluding OTTI									(109,000)	(4,226,000)	(4,171,000)
Net changes in unrealized gains (losses) on investments:											29,000
Net unrealized gains (losses) on equity securities									(299,000)	(355,000)
Equity Method Investments
INVESTMENTS
Net changes in unrealized gains (losses) on investments:									$ 1,109,000	$ (1,257,000)	$ 604,000

INVESTMENTS - Disposition of Fi

INVESTMENTS - Disposition of Fixed Securities and Equities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt securities | Available for sale securities | SALES
Summary of the disposition of fixed maturities and equities
Proceeds From Sales	$ 196,799	$ 394,318	$ 169,002
Gross Realized Gains	4,368	3,131	2,406
Gross Realized Losses	(2,167)	(5,349)	(1,670)
Marketable Securities, Realized Gain (Loss), Excluding Other than Temporary Impairments, Total	2,201	(2,218)	736
Debt securities | Available for sale securities | CALLS/MATURITIES
Summary of the disposition of fixed maturities and equities
Proceeds From Sales	201,698	187,380	195,617
Gross Realized Gains	1,004	311	262
Gross Realized Losses	(21)	(111)	(139)
Marketable Securities, Realized Gain (Loss), Excluding Other than Temporary Impairments, Total	983	200	123
Equity securities | SALES
Summary of the disposition of fixed maturities and equities
Proceeds From Sales	62,172	147,838	36,573
Gross Realized Gains	16,938	71,065	13,178
Gross Realized Losses	(2,493)	(1,197)	(2,896)
Marketable Securities, Realized Gain (Loss), Excluding Other than Temporary Impairments, Total	$ 14,445	$ 69,868	$ 10,282

INVESTMENTS - Assets Measured A

INVESTMENTS - Assets Measured At Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets measured at Fair Value
Available-for-sale fixed income	$ 1,983,086	$ 1,760,515
Equity securities, at fair value (cost - $262,131 in 2019 and $220,373 in 2018)	460,630	340,483
Transfers in (out of) level 1	0	0
Transfers in (out of) level 2	0	0
U.S. government
Assets measured at Fair Value
Available-for-sale fixed income	193,661	200,229
U.S. Agency
Assets measured at Fair Value
Available-for-sale fixed income	38,855	31,904
Non-U.S. govt. & agency
Assets measured at Fair Value
Available-for-sale fixed income	7,628	7,639
Agency MBS
Assets measured at Fair Value
Available-for-sale fixed income	420,165	395,253
ABS/CMBS/MBS
Assets measured at Fair Value
Available-for-sale fixed income	224,870	136,723
Corporate Debt
Assets measured at Fair Value
Available-for-sale fixed income	692,067	668,679
Municipal
Assets measured at Fair Value
Available-for-sale fixed income	405,840	320,088
Fair value measured on recurring basis
Assets measured at Fair Value
Available-for-sale fixed income	1,983,086	1,760,515
Total assets at fair value	2,443,716	2,100,998
Fair value measured on recurring basis | U.S. government
Assets measured at Fair Value
Available-for-sale fixed income	193,661	200,229
Fair value measured on recurring basis | U.S. Agency
Assets measured at Fair Value
Available-for-sale fixed income	38,855	31,904
Fair value measured on recurring basis | Non-U.S. govt. & agency
Assets measured at Fair Value
Available-for-sale fixed income	7,628	7,639
Fair value measured on recurring basis | Agency MBS
Assets measured at Fair Value
Available-for-sale fixed income	420,165	395,253
Fair value measured on recurring basis | ABS/CMBS/MBS
Assets measured at Fair Value
Available-for-sale fixed income	224,870	136,723
Fair value measured on recurring basis | Corporate Debt
Assets measured at Fair Value
Available-for-sale fixed income	692,067	668,679
Fair value measured on recurring basis | Municipal
Assets measured at Fair Value
Available-for-sale fixed income	405,840	320,088
Fair value measured on recurring basis | Equity securities
Assets measured at Fair Value
Equity securities, at fair value (cost - $262,131 in 2019 and $220,373 in 2018)	460,630	340,483
Fair value measured on recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets measured at Fair Value
Total assets at fair value	460,630	339,985
Fair value measured on recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Assets measured at Fair Value
Equity securities, at fair value (cost - $262,131 in 2019 and $220,373 in 2018)	460,630	339,985
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2)
Assets measured at Fair Value
Available-for-sale fixed income	1,981,316	1,760,515
Total assets at fair value	1,981,316	1,761,013
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2) | U.S. government
Assets measured at Fair Value
Available-for-sale fixed income	193,661	200,229
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2) | U.S. Agency
Assets measured at Fair Value
Available-for-sale fixed income	38,855	31,904
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2) | Non-U.S. govt. & agency
Assets measured at Fair Value
Available-for-sale fixed income	7,628	7,639
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2) | Agency MBS
Assets measured at Fair Value
Available-for-sale fixed income	420,165	395,253
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2) | ABS/CMBS/MBS
Assets measured at Fair Value
Available-for-sale fixed income	224,870	136,723
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2) | Corporate Debt
Assets measured at Fair Value
Available-for-sale fixed income	690,297	668,679
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2) | Municipal
Assets measured at Fair Value
Available-for-sale fixed income	405,840	320,088
Fair value measured on recurring basis | Significant Other Observable Inputs (Level 2) | Equity securities
Assets measured at Fair Value
Equity securities, at fair value (cost - $262,131 in 2019 and $220,373 in 2018)		$ 498
Fair value measured on recurring basis | Significant Unobservable Inputs (Level 3)
Assets measured at Fair Value
Available-for-sale fixed income	1,770
Total assets at fair value	1,770
Fair value measured on recurring basis | Significant Unobservable Inputs (Level 3) | Corporate Debt
Assets measured at Fair Value
Available-for-sale fixed income	$ 1,770

INVESTMENTS - Fixed Income Secu

INVESTMENTS - Fixed Income Securities By Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized cost of available-for-sale debt securities by contractual maturity
Due in one year or less	$ 49,951
Due after one year through five years	395,056
Due after five years through 10 years	580,310
Due after 10 years	255,321
Total amortized cost	1,915,278	$ 1,776,465
Fair value of available-for-sale debt securities by contractual maturity
Due in one year or less	50,170
Due after one year through five years	407,007
Due after five years through 10 years	613,099
Due after 10 years	267,775
Total fair value	1,983,086	$ 1,760,515
Mtge/ABS/CMBS
Amortized cost of available-for-sale debt securities by contractual maturity
Total amortized cost	634,640
Fair value of available-for-sale debt securities by contractual maturity
Total fair value	$ 645,035

INVESTMENTS - Investments In Fi

INVESTMENTS - Investments In Fixed Income and Equity Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale
Total amortized cost	$ 1,915,278	$ 1,776,465
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	$ 1,983,086	1,760,515
Percentage of securities of portfolio rated with highest credit rating by by one or more major rating agency	97.00%
Total fixed income and equity securities
Net unrealized appreciation of available-for-sale fixed income securities	$ 67,800	(16,000)
U.S. government
Available-for-sale
Total amortized cost	186,699	199,982
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	193,661	200,229
Gross Unrealized Gains	6,994	1,232
Gross Unrealized Losses	(32)	(985)
U.S. Agency
Available-for-sale
Total amortized cost	36,535	31,716
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	38,855	31,904
Gross Unrealized Gains	2,362	403
Gross Unrealized Losses	(42)	(215)
Non-U.S. govt. & agency
Available-for-sale
Total amortized cost	7,333	8,170
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	7,628	7,639
Gross Unrealized Gains	295
Gross Unrealized Losses		(531)
Mtge/ABS/CMO
Available-for-sale
Gross Unrealized Losses	(1,000)
Agency MBS
Available-for-sale
Total amortized cost	411,808	402,992
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	420,165	395,253
Gross Unrealized Gains	8,920	1,709
Gross Unrealized Losses	(563)	(9,448)
ABS/CMBS/MBS
Available-for-sale
Total amortized cost	222,832	137,224
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	224,870	136,723
Gross Unrealized Gains	2,514	375
Gross Unrealized Losses	(476)	(876)
Corporate Debt
Available-for-sale
Total amortized cost	659,640	681,909
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	692,067	668,679
Gross Unrealized Gains	33,245	2,894
Gross Unrealized Losses	(818)	(16,124)
Municipal
Available-for-sale
Total amortized cost	390,431	314,472
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	405,840	320,088
Gross Unrealized Gains	16,131	6,926
Gross Unrealized Losses	$ (722)	(1,310)
General obligations to state and local governments Percentage	42.00%
Revenue based obligations percentage	58.00%
Percentage of securities of portfolio rated as AA or better	86.00%
Percentage of securities of portfolio rated as A or better	99.00%
Debt securities
Available-for-sale
Total amortized cost	$ 1,915,278	1,776,465
Available-for-sale, at fair value (amortized cost - $1,915,278 in 2019 and $1,776,465 in 2018)	1,983,086	1,760,515
Gross Unrealized Gains	70,461	13,539
Gross Unrealized Losses	(2,653)	$ (29,489)
Equity securities
Equity Securities, FV-NI, Unrealized Gain (Loss)
Increase Decrease In Equity Securities Gross Unrealized Loss	(8,100)
Gross Unrealized Losses	$ 2,000

INVESTMENTS - Types of Debt and

INVESTMENTS - Types of Debt and Equity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt securities
Fair value
Less than 12 months	$ 169,311	$ 397,157
12 months and greater	77,565	584,017
Total Fair Value	246,876	981,174
Cost or amortized Cost
Amortized cost, less than 12 months	171,028	406,953
12 months and greater	78,501	603,710
Total Cost or Amortized Cost	249,529	1,010,663
Unrealized Loss
Less than 12 months	1,717	9,796
12 months and greater	936	19,693
Total Unrealized Loss	2,653	29,489
U.S. government
Fair value
Less than 12 months	2,505	7,249
12 months and greater	8,463	76,073
Total Fair Value	10,968	83,322
Cost or amortized Cost
Amortized cost, less than 12 months	2,506	7,270
12 months and greater	8,494	77,037
Total Cost or Amortized Cost	11,000	84,307
Unrealized Loss
Less than 12 months	1	21
12 months and greater	31	964
Total Unrealized Loss	32	985
U.S. Agency
Fair value
Less than 12 months	6,794
12 months and greater		8,843
Total Fair Value	6,794	8,843
Cost or amortized Cost
Amortized cost, less than 12 months	6,836
12 months and greater		9,058
Total Cost or Amortized Cost	6,836	9,058
Unrealized Loss
Less than 12 months	42
12 months and greater		215
Total Unrealized Loss	42	215
Non-U.S. govt. & agency
Fair value
Less than 12 months		5,432
12 months and greater		2,207
Total Fair Value		7,639
Cost or amortized Cost
Amortized cost, less than 12 months		5,571
12 months and greater		2,599
Total Cost or Amortized Cost		8,170
Unrealized Loss
Less than 12 months		139
12 months and greater		392
Total Unrealized Loss		531
Agency MBS
Fair value
Less than 12 months	21,548	25,345
12 months and greater	41,718	261,325
Total Fair Value	63,266	286,670
Cost or amortized Cost
Amortized cost, less than 12 months	21,664	25,486
12 months and greater	42,165	270,632
Total Cost or Amortized Cost	63,829	296,118
Unrealized Loss
Less than 12 months	116	141
12 months and greater	447	9,307
Total Unrealized Loss	563	9,448
ABS/CMBS/MBS
Fair value
Less than 12 months	74,968	46,918
12 months and greater	18,036	32,137
Total Fair Value	93,004	79,055
Cost or amortized Cost
Amortized cost, less than 12 months	75,332	47,146
12 months and greater	18,148	32,785
Total Cost or Amortized Cost	93,480	79,931
Unrealized Loss
Less than 12 months	364	228
12 months and greater	112	648
Total Unrealized Loss	476	876
Corporate Debt
Fair value
Less than 12 months	16,478	306,177
12 months and greater	9,348	147,751
Total Fair Value	25,826	453,928
Cost or amortized Cost
Amortized cost, less than 12 months	16,950	315,428
12 months and greater	9,694	154,624
Total Cost or Amortized Cost	26,644	470,052
Unrealized Loss
Less than 12 months	472	9,251
12 months and greater	346	6,873
Total Unrealized Loss	818	16,124
Municipal
Fair value
Less than 12 months	47,018	6,036
12 months and greater		55,681
Total Fair Value	47,018	61,717
Cost or amortized Cost
Amortized cost, less than 12 months	47,740	6,052
12 months and greater		56,975
Total Cost or Amortized Cost	47,740	63,027
Unrealized Loss
Less than 12 months	722	16
12 months and greater		1,294
Total Unrealized Loss	$ 722	$ 1,310

INVESTMENTS - Portfolio Analysi

INVESTMENTS - Portfolio Analysis (Details)	12 Months Ended
	Dec. 31, 2019USD ($)securityposition	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Securities in unrealized loss positions
Other-than-temporary impairment (OTTI) losses	$ 0	$ 217,000	$ 2,559,000
Fixed maturities and short-term investments on deposit with either regulatory authorities or banks	69,600,000
Unrealized gains (losses) recognized on equity securities still held at end of period	$ 92,800,000	$ (28,700,000)	$ 47,200,000
Debt securities
Securities in unrealized loss positions
Number of unrealized loss positions | position	154
Number of securities in unrealized loss positions for 12 months or longer | security	65
12 months and greater	$ 900,000

INVESTMENTS - Other Invested As

INVESTMENTS - Other Invested Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other invested assets
Other Investments	$ 70,441	$ 51,542
Qualified Affordable Housing Project Investments, Commitment	8,600
Investments pledged as collateral	$ 15,500
Investment in Federal Home Loan Bank Stock	us-gaap:AssetPledgedAsCollateralMember
Federal Home Loan Bank Borrowings, Fair Value Disclosure	$ 0
Investment In Low Income Housing Tax Credit Partnership Net Of Amortization
Other invested assets
Other Investments	23,300	20,300
Qualified Affordable Housing Project Investments, Commitment	8,600
Total tax benefit on investments in housing tax credit partnership	2,500	2,200	$ 2,400
Investment in Private Funds
Other invested assets
Other Investments	46,000	$ 30,300
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 15,500

POLICY ACQUISITION COSTS (Detai

POLICY ACQUISITION COSTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Policy acquisition costs deferred and amortized to income
Deferred policy acquisition costs (DAC), beginning of year	$ 84,934	$ 77,716	$ 73,147
Deferred:
Direct commissions	185,164	175,697	157,723
Premium taxes	14,395	12,654	11,651
Ceding commissions	(31,140)	(22,190)	(18,096)
Net deferred	168,419	166,161	151,278
Amortized	168,309	158,943	146,709
DAC, end of year	85,044	84,934	77,716
Policy acquisition costs:
Amortized to expense - DAC	168,309	158,943	146,709
Period costs:
Ceding commission - contingent	(3,034)	(2,241)	(3,575)
Other underwriting expenses	123,422	111,036	109,381
Total policy acquisition costs	$ 288,697	$ 267,738	$ 252,515

DEBT (Details)

DEBT (Details) - USD ($) $ in Thousands	Oct. 02, 2013	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt
Outstanding long-term senior notes		$ 149,302	$ 149,115
Interest Paid		$ 7,300	$ 7,300	$ 7,300
Senior Notes
Debt
Average interest rate on debt (as a percent)		4.91%	4.91%	4.91%
Senior notes maturing September 15, 2023
Debt
Issue of senior notes by public debt offering	$ 150,000
Stated interest rate, payable semi-annually (as a percent)	4.875%
Proceeds from issuance of debt, net of discount and commission	$ 148,600
Estimated fair value of senior notes		$ 161,200
Line of credit
Debt
Borrowing capacity under revolving line of credit facility		50,000
Maximum borrowing capacity conditional expansion		$ 75,000
Term of facility		2 years
Amount outstanding on this facility		$ 0	$ 0	$ 0

REINSURANCE - Summary of Premiu

REINSURANCE - Summary of Premiums and Losses (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
REINSURANCE
Maximum amount beyond which net loss on any individual risk is limited through the purchase of reinsurance	$ 3,000								$ 3,000
WRITTEN
Direct									1,039,955	$ 934,913	$ 848,153
Reinsurance assumed									25,047	48,303	37,159
Reinsurance ceded									(204,665)	(160,041)	(135,458)
Net									860,337	823,175	749,854
EARNED
Direct									981,121	896,234	835,118
Reinsurance assumed									40,173	41,926	32,521
Reinsurance ceded									(182,183)	(146,794)	(129,702)
Net amount	$ 215,626	$ 211,255	$ 207,541	$ 204,689	$ 204,002	$ 200,815	$ 196,522	$ 190,027	839,111	791,366	737,937
LOSSES AND SETTLEMENT EXPENSES INCURRED
Direct									521,055	560,421	486,986
Reinsurance assumed									21,951	20,376	16,072
Reinsurance ceded									(129,590)	(152,604)	(101,474)
Net									$ 413,416	$ 428,193	$ 401,584

REINSURANCE - Summary of Reinsu

REINSURANCE - Summary of Reinsurers (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net reinsurance balances recoverable
Percentage of reinsurance recoverables due from companies with financial strength ratings of "A" or better by A.M. Best and S&P rating services	94.00%
Reinsurer Exposure	$ 469,151
Ceded Premium Written	$ 204,665	$ 160,041	$ 135,458
Percent of Total Ceded Premium Written	100.00%
Reinsurance balances recoverable as a percentage of shareholder's equity, threshold for disclosure	2.00%
Amount of allowance for uncollectible amounts on paid recoverables	$ 15,700	16,100
Reinsurance balances recoverable on unpaid losses and settlement expenses, allowances for uncollectible amounts	$ 9,402	$ 9,793
Threshold period for including reinsurance receivables in the allowance for uncollectible amounts	1 year
Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	100.00%
Munich Re America / HSB | AM Best Rating, A+, Superior | S&P Rating, AA-, Very Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 68,368
Ceded Premium Written	$ 22,536
Percent of Total Ceded Premium Written	11.00%
Munich Re America / HSB | AM Best Rating, A+, Superior | S&P Rating, AA-, Very Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	14.60%
Swiss Re /Westport Ins. Corp. | AM Best Rating, A+, Superior | S&P Rating, AA-, Very Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 34,777
Ceded Premium Written	$ 2,801
Percent of Total Ceded Premium Written	1.40%
Swiss Re /Westport Ins. Corp. | AM Best Rating, A+, Superior | S&P Rating, AA-, Very Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	7.40%
Endurance Re | AM Best Rating, A+, Superior | S&P Rating, A+, Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 32,233
Ceded Premium Written	$ 9,173
Percent of Total Ceded Premium Written	4.50%
Endurance Re | AM Best Rating, A+, Superior | S&P Rating, A+, Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	6.90%
Aspen UK Ltd. | AM Best Rating, A, Excellent | S&P Rating, A, Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 31,622
Ceded Premium Written	$ 8,270
Percent of Total Ceded Premium Written	4.00%
Aspen UK Ltd. | AM Best Rating, A, Excellent | S&P Rating, A, Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	6.70%
Berkley Insurance Co. | AM Best Rating, A+, Superior | S&P Rating, A+, Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 28,798
Ceded Premium Written	$ 8,667
Percent of Total Ceded Premium Written	4.20%
Berkley Insurance Co. | AM Best Rating, A+, Superior | S&P Rating, A+, Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	6.10%
Renaissance Re | AM Best Rating, A+, Superior | S&P Rating, A+, Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 25,841
Ceded Premium Written	$ 15,754
Percent of Total Ceded Premium Written	7.70%
Renaissance Re | AM Best Rating, A+, Superior | S&P Rating, A+, Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	5.50%
Hannover Ruckversicherung Member | AM Best Rating, A+, Superior | S&P Rating, AA-, Very Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 24,758
Ceded Premium Written	$ 12,491
Percent of Total Ceded Premium Written	6.10%
Hannover Ruckversicherung Member | AM Best Rating, A+, Superior | S&P Rating, AA-, Very Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	5.30%
Toa-Re | AM Best Rating, A, Excellent | S&P Rating, A+, Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 23,734
Ceded Premium Written	$ 7,757
Percent of Total Ceded Premium Written	3.80%
Toa-Re | AM Best Rating, A, Excellent | S&P Rating, A+, Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	5.10%
Transatlantic Re | AM Best Rating, A+, Superior | S&P Rating, A+, Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 22,873
Ceded Premium Written	$ 6,635
Percent of Total Ceded Premium Written	3.20%
Transatlantic Re | AM Best Rating, A+, Superior | S&P Rating, A+, Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	4.90%
General Re | AM Best, A++ Rating | Standard & Poor's, AA+ Rating
Net reinsurance balances recoverable
Reinsurer Exposure	$ 19,736
Ceded Premium Written	$ 6,240
Percent of Total Ceded Premium Written	3.00%
General Re | AM Best, A++ Rating | Standard & Poor's, AA+ Rating | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	4.20%
Liberty Mutual | AM Best Rating, A, Excellent | S&P Rating, A, Strong
Net reinsurance balances recoverable
Reinsurer Exposure	$ 19,171
Ceded Premium Written	$ 6,696
Percent of Total Ceded Premium Written	3.30%
Liberty Mutual | AM Best Rating, A, Excellent | S&P Rating, A, Strong | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	4.10%
All other reinsurers
Net reinsurance balances recoverable
Reinsurer Exposure	$ 137,240
Ceded Premium Written	$ 97,645
Percent of Total Ceded Premium Written	47.80%
All other reinsurers | Reinsurer Concentration Risk | Reinsurance Recoverable
Net reinsurance balances recoverable
Percent of Total Net Reinsurer Exposure	29.20%

HISTORICAL LOSS AND LAE DEVEL_3

HISTORICAL LOSS AND LAE DEVELOPMENT - Unpaid Losses and Settlement Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unpaid losses and LAE at beginning of year:
Gross	$ 1,461,348	$ 1,271,503	$ 1,139,337
Ceded	(364,999)	(301,991)	(288,224)
Net	1,096,349	969,512	851,113
Increase (decrease) in incurred losses and LAE:
Current accident year	488,700	478,143	440,452
Prior accident years	(75,284)	(49,950)	(38,868)
Total incurred	413,416	428,193	401,584
Loss and LAE payments for claims incurred:
Current accident year	(80,055)	(76,050)	(73,392)
Prior accident year	(239,875)	(225,306)	(209,793)
Total paid	(319,930)	(301,356)	(283,185)
Net	1,189,835	1,096,349	969,512
Unpaid losses and LAE at year end
Gross	1,574,352	1,461,348	1,271,503
Ceded	(384,517)	(364,999)	(301,991)
Net	1,189,835	1,096,349	969,512
Casualty segment
Increase (decrease) in incurred losses and LAE:
Current accident year	392,653	363,015	323,141
Prior accident years	(62,497)	(33,252)	(17,462)
Property segment
Unpaid losses and LAE at beginning of year:
Ceded	(50,495)
Increase (decrease) in incurred losses and LAE:
Current accident year	78,075	94,635	97,161
Prior accident years	(4,461)	(10,813)	(12,134)
Unpaid losses and LAE at year end
Ceded	(21,438)	(50,495)
Surety segment
Unpaid losses and LAE at beginning of year:
Ceded	(11,834)
Increase (decrease) in incurred losses and LAE:
Current accident year	17,972	20,493	20,150
Prior accident years	(8,326)	(5,885)	$ (9,272)
Unpaid losses and LAE at year end
Ceded	$ (11,199)	$ (11,834)

HISTORICAL LOSS AND LAE DEVEL_4

HISTORICAL LOSS AND LAE DEVELOPMENT - Incurred Losses and Loss Adjustment Expenses, Net of Reinsurance (Details) $ in Thousands	Dec. 31, 2019USD ($)claim	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)
Claims Development
Liabilities for losses and loss adjustment expenses, net of reinsurance	$ 1,189,835	$ 1,096,349
Casualty segment | Primary Occurrence
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	888,240
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	495,044
All outstanding liabilities before 2009, net of reinsurance	10,714
Liabilities for losses and loss adjustment expenses, net of reinsurance	403,910	372,450
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2010
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	79,656	80,216	$ 78,991	$ 78,685	$ 80,289	$ 85,034	$ 88,820	$ 93,589	$ 96,582	$ 87,875
Total IBNR	$ 1,922
Cumulative number of reported claims | claim	6,128
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 75,007	73,318	69,514	66,399	61,929	55,992	44,051	29,312	13,025	2,587
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2011
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	81,579	82,248	82,193	83,181	86,342	89,622	94,145	98,428	91,139
Total IBNR	$ 2,546
Cumulative number of reported claims | claim	5,862
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 76,318	74,814	71,413	67,358	60,769	48,822	32,978	17,124	5,924
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2012
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	60,465	60,328	59,488	59,028	61,072	65,893	78,406	91,807
Total IBNR	$ 2,922
Cumulative number of reported claims | claim	5,179
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 54,391	51,611	47,970	43,276	33,822	23,889	14,539	5,897
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2013
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	59,116	59,556	60,162	60,329	62,882	67,297	80,823
Total IBNR	$ 4,917
Cumulative number of reported claims | claim	4,307
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 47,783	45,753	40,609	34,786	22,366	13,021	6,334
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2014
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	66,702	66,389	67,237	71,592	79,497	88,092
Total IBNR	$ 8,251
Cumulative number of reported claims | claim	4,266
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 52,387	47,343	40,270	29,545	18,771	11,436
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2015
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	76,398	78,675	83,579	84,975	94,835
Total IBNR	$ 14,891
Cumulative number of reported claims | claim	4,362
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 54,270	45,056	33,020	19,902	10,157
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2016
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	85,449	90,611	96,753	101,950
Total IBNR	$ 24,712
Cumulative number of reported claims | claim	4,240
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 48,042	35,764	24,186	10,142
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2017
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	102,583	111,391	119,741
Total IBNR	$ 46,557
Cumulative number of reported claims | claim	4,336
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 38,783	25,933	13,154
Casualty segment | Primary Occurrence | Short-duration Insurance Contracts, Accident Year 2018
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	130,281	141,513
Total IBNR	$ 79,489
Cumulative number of reported claims | claim	4,490
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 32,365	15,066
Casualty segment | Primary Occurrence | Short-Duration Insurance Contract, Accident Year 2019 [Member]
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	146,011
Total IBNR	$ 119,051
Cumulative number of reported claims | claim	4,193
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 15,698
Casualty segment | Excess Occurrence
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	402,184
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	162,440
All outstanding liabilities before 2009, net of reinsurance	16,409
Liabilities for losses and loss adjustment expenses, net of reinsurance	256,153	209,683
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2010
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	20,579	20,527	20,530	21,018	22,044	20,044	18,932	22,111	24,244	29,314
Total IBNR	$ 315
Cumulative number of reported claims | claim	503
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 19,390	19,308	19,256	19,175	17,302	15,512	13,282	10,705	6,002	7
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2011
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	21,825	22,032	21,295	20,959	19,160	18,641	17,443	17,148	26,272
Total IBNR	$ 625
Cumulative number of reported claims | claim	581
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 21,036	20,214	17,769	16,494	10,772	8,793	6,981	5,145	2,169
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2012
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	25,286	23,020	22,433	21,231	21,885	21,021	21,558	29,042
Total IBNR	$ 1,016
Cumulative number of reported claims | claim	858
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 21,993	19,310	17,747	16,879	15,380	8,843	3,573	1,315
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2013
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	25,496	24,922	25,599	25,425	26,857	34,824	39,984
Total IBNR	$ 2,220
Cumulative number of reported claims | claim	939
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 18,524	17,956	16,967	14,545	10,967	5,701	1,060
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2014
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	33,458	33,372	32,274	35,119	39,095	50,889
Total IBNR	$ 6,322
Cumulative number of reported claims | claim	887
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 23,376	22,541	18,852	11,002	4,006	1,899
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2015
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	43,328	42,840	47,392	50,857	53,672
Total IBNR	$ 10,833
Cumulative number of reported claims | claim	685
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 28,756	23,184	19,571	10,127	2,048
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2016
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	33,125	37,676	49,385	56,341
Total IBNR	$ 18,457
Cumulative number of reported claims | claim	624
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 10,054	7,441	3,396	1,068
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2017
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	48,363	55,868	62,863
Total IBNR	$ 31,333
Cumulative number of reported claims | claim	563
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 9,275	5,679	17
Casualty segment | Excess Occurrence | Short-duration Insurance Contracts, Accident Year 2018
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	62,646	69,362
Total IBNR	$ 51,501
Cumulative number of reported claims | claim	452
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 5,823	2,506
Casualty segment | Excess Occurrence | Short-Duration Insurance Contract, Accident Year 2019 [Member]
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	88,078
Total IBNR	$ 66,592
Cumulative number of reported claims | claim	293
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 4,213
Casualty segment | Claims Made
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	431,118
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	215,563
All outstanding liabilities before 2009, net of reinsurance	2,399
Liabilities for losses and loss adjustment expenses, net of reinsurance	217,954	204,501
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2010
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	8,680	8,735	9,024	9,175	10,581	11,689	10,429	9,776	15,556	13,690
Total IBNR	$ 160
Cumulative number of reported claims | claim	502
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 8,515	8,512	8,485	6,956	5,749	5,733	3,626	2,308	1,548	259
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2011
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	14,031	11,506	7,852	7,720	8,510	10,619	12,260	17,454	17,416
Total IBNR	$ 592
Cumulative number of reported claims | claim	682
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 7,239	7,132	6,835	6,209	5,637	5,947	4,508	1,949	330
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2012
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	20,785	17,569	17,612	18,022	19,590	20,727	26,144	27,576
Total IBNR	$ 1,781
Cumulative number of reported claims | claim	803
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 16,450	15,621	14,378	10,968	9,218	6,898	4,086	433
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2013
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	38,352	37,959	38,473	40,288	44,054	41,488	40,095
Total IBNR	$ 2,255
Cumulative number of reported claims | claim	1,042
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 34,535	32,789	29,678	26,121	18,425	7,073	792
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2014
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	53,841	51,554	55,350	58,152	55,386	53,929
Total IBNR	$ 4,391
Cumulative number of reported claims | claim	1,305
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 44,127	40,080	35,755	27,923	9,775	1,705
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2015
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	39,653	39,906	42,206	47,831	55,006
Total IBNR	$ 6,376
Cumulative number of reported claims | claim	1,336
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 28,795	20,920	16,774	10,738	2,215
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2016
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	67,728	69,493	67,760	59,992
Total IBNR	$ 16,541
Cumulative number of reported claims | claim	1,506
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 39,370	27,465	14,558	2,060
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2017
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	62,714	62,450	60,572
Total IBNR	$ 24,377
Cumulative number of reported claims | claim	1,633
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 22,728	11,350	2,455
Casualty segment | Claims Made | Short-duration Insurance Contracts, Accident Year 2018
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	62,416	66,128
Total IBNR	$ 37,809
Cumulative number of reported claims | claim	1,381
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 11,965	1,964
Casualty segment | Claims Made | Short-Duration Insurance Contract, Accident Year 2019 [Member]
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	62,918
Total IBNR	$ 50,178
Cumulative number of reported claims | claim	1,411
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 1,839
Casualty segment | Transportation
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	408,580
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	268,881
All outstanding liabilities before 2009, net of reinsurance	252
Liabilities for losses and loss adjustment expenses, net of reinsurance	139,951	133,558
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2010
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	23,860	23,776	23,786	23,701	23,625	23,981	25,593	24,912	23,390	27,239
Total IBNR	$ 23
Cumulative number of reported claims | claim	2,843
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 23,635	23,556	23,533	23,488	23,063	21,792	20,045	15,475	10,116	6,296
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2011
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	25,827	25,614	25,167	25,376	25,431	25,272	25,747	23,479	22,957
Total IBNR	$ 41
Cumulative number of reported claims | claim	2,469
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 25,052	24,377	23,941	23,537	22,375	19,443	14,477	9,485	5,295
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2012
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	23,731	23,305	23,620	23,689	23,511	22,924	22,203	21,452
Total IBNR	$ 47
Cumulative number of reported claims | claim	2,285
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 23,180	22,730	22,566	20,931	17,318	12,394	8,533	4,466
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2013
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	39,309	39,974	38,811	37,673	32,989	32,853	32,742
Total IBNR	$ 140
Cumulative number of reported claims | claim	2,853
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 37,327	35,923	33,480	28,220	19,761	11,978	5,306
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2014
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	40,508	40,202	38,590	36,452	33,015	38,361
Total IBNR	$ 458
Cumulative number of reported claims | claim	3,099
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 38,282	33,190	27,457	19,676	13,933	7,125
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2015
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	45,162	46,395	47,021	46,258	38,561
Total IBNR	$ 1,574
Cumulative number of reported claims | claim	3,183
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 39,339	37,222	29,554	20,709	6,984
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2016
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	52,277	54,105	53,519	50,430
Total IBNR	$ 4,241
Cumulative number of reported claims | claim	3,935
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 38,001	30,354	18,354	8,923
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2017
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	45,017	53,641	55,640
Total IBNR	$ 7,476
Cumulative number of reported claims | claim	3,625
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 24,090	17,070	7,979
Casualty segment | Transportation | Short-duration Insurance Contracts, Accident Year 2018
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	54,592	57,597
Total IBNR	$ 24,385
Cumulative number of reported claims | claim	3,376
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 12,827	6,980
Casualty segment | Transportation | Short-Duration Insurance Contract, Accident Year 2019 [Member]
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	58,297
Total IBNR	$ 17,932
Cumulative number of reported claims | claim	3,082
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 7,148
Property segment
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	653,260
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	581,409
All outstanding liabilities before 2009, net of reinsurance	114
Liabilities for losses and loss adjustment expenses, net of reinsurance	71,965	77,238
Property segment | Short-duration Insurance Contracts, Accident Year 2010
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	52,548	52,903	52,952	52,964	52,927	54,153	53,937	55,427	59,145	63,194
Total IBNR	$ 10
Cumulative number of reported claims | claim	2,850
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 52,538	52,855	52,851	52,719	52,426	52,729	50,055	47,743	43,091	25,274
Property segment | Short-duration Insurance Contracts, Accident Year 2011
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	62,799	62,875	62,456	62,570	62,770	63,724	64,976	66,924	70,246
Total IBNR	$ 65
Cumulative number of reported claims | claim	3,028
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 62,730	62,729	61,834	61,428	60,272	59,099	55,778	48,756	27,676
Property segment | Short-duration Insurance Contracts, Accident Year 2012
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	78,002	78,161	78,125	79,175	77,569	79,181	80,155	85,485
Total IBNR	$ 97
Cumulative number of reported claims | claim	2,640
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 77,323	77,159	76,152	75,640	73,705	72,057	66,509	39,074
Property segment | Short-duration Insurance Contracts, Accident Year 2013
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	61,776	61,834	61,914	62,114	62,173	62,090	63,864
Total IBNR	$ 183
Cumulative number of reported claims | claim	2,995
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 61,325	61,195	60,520	59,259	57,407	50,840	32,208
Property segment | Short-duration Insurance Contracts, Accident Year 2014
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	49,444	49,217	48,761	48,801	49,441	56,587
Total IBNR	$ 158
Cumulative number of reported claims | claim	4,561
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 49,027	47,799	46,528	46,148	43,380	30,550
Property segment | Short-duration Insurance Contracts, Accident Year 2015
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	53,111	52,720	53,958	56,103	59,863
Total IBNR	$ 403
Cumulative number of reported claims | claim	4,075
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 52,078	51,290	50,197	49,348	32,184
Property segment | Short-duration Insurance Contracts, Accident Year 2016
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	55,930	55,384	55,594	62,900
Total IBNR	$ 1,418
Cumulative number of reported claims | claim	3,371
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 53,006	51,371	46,921	33,134
Property segment | Short-duration Insurance Contracts, Accident Year 2017
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	84,961	83,273	90,803
Total IBNR	$ 5,861
Cumulative number of reported claims | claim	2,883
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 74,415	66,818	41,314
Property segment | Short-duration Insurance Contracts, Accident Year 2018
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	83,457	89,091
Total IBNR	$ 10,867
Cumulative number of reported claims | claim	2,321
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 68,264	37,048
Property segment | Short-Duration Insurance Contract, Accident Year 2019 [Member]
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	71,232
Total IBNR	$ 27,090
Cumulative number of reported claims | claim	2,098
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 30,703
Surety segment
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	91,143
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	68,151
All outstanding liabilities before 2009, net of reinsurance	1,996
Liabilities for losses and loss adjustment expenses, net of reinsurance	24,988	28,237
Surety segment | Short-duration Insurance Contracts, Accident Year 2010
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	6,743	6,580	6,244	7,645	7,136	6,810	7,076	6,630	8,205	13,961
Total IBNR	$ 47
Cumulative number of reported claims | claim	1,543
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 6,733	6,637	6,663	7,822	7,285	7,151	7,092	5,702	3,205	$ 1,724
Surety segment | Short-duration Insurance Contracts, Accident Year 2011
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	18,293	18,281	16,480	16,695	16,766	17,321	17,792	17,832	13,842
Total IBNR	$ 35
Cumulative number of reported claims | claim	1,679
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 18,251	17,013	17,086	17,086	17,212	17,403	17,151	16,932	$ 8,160
Surety segment | Short-duration Insurance Contracts, Accident Year 2012
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	7,082	7,099	7,471	7,867	8,180	8,667	11,452	17,114
Total IBNR	$ 38
Cumulative number of reported claims | claim	1,474
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 6,996	7,065	7,406	7,536	7,416	6,726	6,680	$ 1,883
Surety segment | Short-duration Insurance Contracts, Accident Year 2013
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	5,209	5,231	5,271	5,399	6,170	7,516	16,080
Total IBNR	$ 65
Cumulative number of reported claims | claim	1,406
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 5,128	5,150	5,098	4,911	4,701	2,856	$ 1,116
Surety segment | Short-duration Insurance Contracts, Accident Year 2014
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	4,319	4,267	4,427	5,225	8,106	16,450
Total IBNR	$ 67
Cumulative number of reported claims | claim	1,346
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 4,234	4,131	4,059	4,166	4,283	$ 722
Surety segment | Short-duration Insurance Contracts, Accident Year 2015
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	9,792	10,456	11,113	12,957	16,958
Total IBNR	$ 384
Cumulative number of reported claims | claim	1,217
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 9,183	9,436	7,695	6,719	$ 3,192
Surety segment | Short-duration Insurance Contracts, Accident Year 2016
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	8,895	9,351	11,062	18,928
Total IBNR	$ 742
Cumulative number of reported claims | claim	1,359
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 7,640	6,299	5,817	$ 3,087
Surety segment | Short-duration Insurance Contracts, Accident Year 2017
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	8,798	8,641	16,127
Total IBNR	$ 1,469
Cumulative number of reported claims | claim	1,645
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 7,062	2,862	$ 979
Surety segment | Short-duration Insurance Contracts, Accident Year 2018
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	7,227	16,765
Total IBNR	$ 3,965
Cumulative number of reported claims | claim	1,157
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 2,588	$ 1,835
Surety segment | Short-Duration Insurance Contract, Accident Year 2019 [Member]
Claims Development
Incurred losses and loss adjustment expenses, net of reinsurance	14,785
Total IBNR	$ 14,035
Cumulative number of reported claims | claim	607
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	$ 336

HISTORICAL LOSS AND LAE DEVEL_5

HISTORICAL LOSS AND LAE DEVELOPMENT - Cumulative Paid Loss and Loss Adjustment Expenses, Net of Reinsurance (Details)	Dec. 31, 2019
Property segment
Short-duration Insurance Contracts, Historical Claims Duration
Average annual percentage payout of incurred losses by age, Year 1	51.20%
Average annual percentage payout of incurred losses by age, Year 2	31.50%
Average annual percentage payout of incurred losses by age, Year 3	7.70%
Average annual percentage payout of incurred losses by age, Year 4	2.90%
Average annual percentage payout of incurred losses by age, Year 5	2.60%
Average annual percentage payout of incurred losses by age, Year 6	1.10%
Average annual percentage payout of incurred losses by age, Year 7	0.70%
Average annual percentage payout of incurred losses by age, Year 8	0.60%
Average annual percentage payout of incurred losses by age, Year 9	0.00%
Average annual percentage payout of incurred losses by age, Year 10	(0.60%)
Surety segment
Short-duration Insurance Contracts, Historical Claims Duration
Average annual percentage payout of incurred losses by age, Year 1	24.10%
Average annual percentage payout of incurred losses by age, Year 2	39.10%
Average annual percentage payout of incurred losses by age, Year 3	16.80%
Average annual percentage payout of incurred losses by age, Year 4	9.40%
Average annual percentage payout of incurred losses by age, Year 5	0.70%
Average annual percentage payout of incurred losses by age, Year 6	0.60%
Average annual percentage payout of incurred losses by age, Year 7	0.70%
Average annual percentage payout of incurred losses by age, Year 8	(6.20%)
Average annual percentage payout of incurred losses by age, Year 9	3.20%
Average annual percentage payout of incurred losses by age, Year 10	1.40%
Primary Occurrence | Casualty segment
Short-duration Insurance Contracts, Historical Claims Duration
Average annual percentage payout of incurred losses by age, Year 1	10.80%
Average annual percentage payout of incurred losses by age, Year 2	13.20%
Average annual percentage payout of incurred losses by age, Year 3	16.30%
Average annual percentage payout of incurred losses by age, Year 4	17.40%
Average annual percentage payout of incurred losses by age, Year 5	13.00%
Average annual percentage payout of incurred losses by age, Year 6	7.90%
Average annual percentage payout of incurred losses by age, Year 7	5.00%
Average annual percentage payout of incurred losses by age, Year 8	4.20%
Average annual percentage payout of incurred losses by age, Year 9	3.30%
Average annual percentage payout of incurred losses by age, Year 10	2.10%
Excess Occurrence | Casualty segment
Short-duration Insurance Contracts, Historical Claims Duration
Average annual percentage payout of incurred losses by age, Year 1	4.20%
Average annual percentage payout of incurred losses by age, Year 2	13.20%
Average annual percentage payout of incurred losses by age, Year 3	16.90%
Average annual percentage payout of incurred losses by age, Year 4	14.30%
Average annual percentage payout of incurred losses by age, Year 5	9.90%
Average annual percentage payout of incurred losses by age, Year 6	8.90%
Average annual percentage payout of incurred losses by age, Year 7	5.80%
Average annual percentage payout of incurred losses by age, Year 8	7.40%
Average annual percentage payout of incurred losses by age, Year 9	2.00%
Average annual percentage payout of incurred losses by age, Year 10	0.40%
Claims Made | Casualty segment
Short-duration Insurance Contracts, Historical Claims Duration
Average annual percentage payout of incurred losses by age, Year 1	3.10%
Average annual percentage payout of incurred losses by age, Year 2	16.20%
Average annual percentage payout of incurred losses by age, Year 3	19.50%
Average annual percentage payout of incurred losses by age, Year 4	14.20%
Average annual percentage payout of incurred losses by age, Year 5	11.30%
Average annual percentage payout of incurred losses by age, Year 6	7.30%
Average annual percentage payout of incurred losses by age, Year 7	7.20%
Average annual percentage payout of incurred losses by age, Year 8	7.90%
Average annual percentage payout of incurred losses by age, Year 9	0.50%
Average annual percentage payout of incurred losses by age, Year 10	0.00%
Transportation | Casualty segment
Short-duration Insurance Contracts, Historical Claims Duration
Average annual percentage payout of incurred losses by age, Year 1	17.20%
Average annual percentage payout of incurred losses by age, Year 2	18.10%
Average annual percentage payout of incurred losses by age, Year 3	18.80%
Average annual percentage payout of incurred losses by age, Year 4	18.80%
Average annual percentage payout of incurred losses by age, Year 5	11.00%
Average annual percentage payout of incurred losses by age, Year 6	7.10%
Average annual percentage payout of incurred losses by age, Year 7	1.90%
Average annual percentage payout of incurred losses by age, Year 8	1.30%
Average annual percentage payout of incurred losses by age, Year 9	1.40%
Average annual percentage payout of incurred losses by age, Year 10	0.30%

HISTORICAL LOSS AND LAE DEVEL_6

HISTORICAL LOSS AND LAE DEVELOPMENT - Reconciliation of Incurred and Paid Loss Development to the Liability for Unpaid Losses and Settlement Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net outstanding liabilities	$ 1,574,352	$ 1,461,348	$ 1,271,503	$ 1,139,337
Unallocated loss adjustment expenses	52,275	50,891
Other	13,237	9,998
Liabilities for losses and loss adjustment expenses, net of reinsurance	1,189,835	1,096,349
Allowance for uncollectible reinsurance balances recoverable on unpaid losses and settlement expenses	9,402	9,793
Other	982	980
Reinsurance recoverable on unpaid claims	384,517	364,999	$ 301,991	$ 288,224
Total gross liability for unpaid loss and settlement expenses	1,574,352	1,461,348
Casualty segment | Primary Occurrence
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Liabilities for losses and loss adjustment expenses, net of reinsurance	403,910	372,450
Reinsurance recoverable on unpaid claims	31,122	34,742
Casualty segment | Excess Occurrence
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Liabilities for losses and loss adjustment expenses, net of reinsurance	256,153	209,683
Reinsurance recoverable on unpaid claims	98,518	81,072
Casualty segment | Claims Made
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Liabilities for losses and loss adjustment expenses, net of reinsurance	217,954	204,501
Reinsurance recoverable on unpaid claims	176,936	144,921
Casualty segment | Transportation
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Liabilities for losses and loss adjustment expenses, net of reinsurance	139,951	133,558
Reinsurance recoverable on unpaid claims	53,724	50,748
Property segment
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Liabilities for losses and loss adjustment expenses, net of reinsurance	71,965	77,238
Reinsurance recoverable on unpaid claims	21,438	50,495
Surety segment
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Liabilities for losses and loss adjustment expenses, net of reinsurance	24,988	28,237
Reinsurance recoverable on unpaid claims	$ 11,199	$ 11,834

HISTORICAL LOSS AND LAE DEVEL_7

HISTORICAL LOSS AND LAE DEVELOPMENT - Reserve Development (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	$ (75,284)	$ (49,950)	$ (38,868)
Casualty segment
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(62,497)	(33,252)	(17,462)
Property segment
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(4,461)	(10,813)	(12,134)
Property segment | Marine
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(2,400)	(5,000)	(6,800)
Property segment | Assumed property
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development		(2,800)
Property segment | Commercial property
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development		(2,000)	(3,200)
Property segment | Specialty Personal
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(1,100)
Surety segment
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(8,326)	(5,885)	(9,272)
Surety segment | Commercial surety product
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(5,800)	(6,300)	(5,000)
Surety segment | Contract surety product
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(4,200)		(4,400)
Surety segment | Miscellaneous Surety Product
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	1,700	800	100
Primary Occurrence | Casualty segment
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development		(15,600)
Primary Occurrence | Casualty segment | General liability
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(11,800)	(6,700)	(4,600)
Primary Occurrence | Casualty segment | P&C Package
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(6,300)		(3,200)
Excess Occurrence | Casualty segment
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development		(21,400)
Excess Occurrence | Casualty segment | Commercial products
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(6,800)	(10,800)	(9,900)
Excess Occurrence | Casualty segment | Personal umbrella
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(7,800)		(1,100)
Claims Made | Casualty segment
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development		3,900
Claims Made | Casualty segment | Executive products
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	7,300		(4,400)
Claims Made | Casualty segment | Medical professional liability
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	2,300		3,700
Claims Made | Casualty segment | Miscellaneous Professional Liability Member
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	(10,200)
Transportation | Casualty segment
(Favorable)/unfavorable reserve development
(Favorable)/unfavorable reserve development	$ (16,600)	$ (500)	$ 7,400

HISTORICAL LOSS AND LAE DEVEL_8

HISTORICAL LOSS AND LAE DEVELOPMENT - Environmental, Asbestos and Mass Tort Exposures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
UNPAID LOSSES AND LAE AT END OF YEAR
Gross	$ 1,574,352	$ 1,461,348	$ 1,271,503	$ 1,139,337
Net	$ 1,189,835	1,096,349	969,512	$ 851,113
Minimum period for which product lines related to majority of reserves have been in runoff	20 years
Asbestos and environmental exposures
LOSS AND LAE PAYMENTS (CUMULATIVE)
Gross	$ 137,485	136,043	132,883
Ceded	(68,849)	(68,638)	(67,507)
Net	68,636	67,405	65,376
UNPAID LOSSES AND LAE AT END OF YEAR
Gross	22,616	24,262	28,042
Ceded	(5,149)	(5,373)	(5,715)
Net	$ 17,467	$ 18,889	$ 22,327

INCOME TAXES (Details)

INCOME TAXES (Details)	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Deferred tax assets:
Tax discounting of claim reserves	$ 19,143,000	$ 18,327,000
Unearned premium offset	18,755,000	17,864,000
Deferred compensation	2,981,000	2,700,000
Stock option expense	2,728,000	2,702,000
Deferred tax asset lease liabilities	5,140,000
Other	275,000	616,000
Deferred tax assets before allowance	49,022,000	42,209,000
Total deferred tax assets	49,022,000	42,209,000
Deferred tax liabilities:
Net unrealized appreciation of securities	56,532,000	22,177,000
Deferred policy acquisition costs	17,859,000	17,836,000
Deferred tax liability lease assets	4,690,000
Deferred Tax Liabilities Discounting Of Unpaid Losses TCJA Offset	3,817,000	5,203,000
Book/tax depreciation	3,008,000	3,133,000
Intangible assets	1,634,000	1,711,000
Undistributed earnings of unconsolidated investees	17,673,000	15,811,000
Other	536,000	576,000
Total deferred tax liabilities	105,749,000	66,447,000
Net deferred tax liability	$ (56,727,000)	$ (24,238,000)
U.S. federal tax rate (as a percent)	21.00%	21.00%	35.00%
Increase (reduction) in taxes resulting from:
Provision for income taxes at the statutory federal tax rate	$ 48,874,000	$ 14,192,000	$ 29,606,000
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act, Amount		(2,268,000)	(32,821,000)
Excess tax benefit on share-based compensation	(3,958,000)	(4,533,000)	(5,798,000)
Dividends received deduction	(823,000)	(775,000)	(2,025,000)
ESOP dividends paid deduction	(1,122,000)	(1,184,000)	(2,905,000)
Tax-exempt interest income	(1,238,000)	(1,795,000)	(4,671,000)
Unconsolidated investee dividends	(1,802,000)		(1,351,000)
Nondeductible expenses	1,649,000	389,000	276,000
Other items, net	(488,000)	(624,000)	(750,000)
Income tax expense	$ 41,092,000	$ 3,402,000	$ (20,439,000)
Reconciliation of income tax expense rate to the U.S. federal tax rate
U.S. federal tax rate (as a percent)	21.00%	21.00%	35.00%
Enactment of Tax Cuts and Jobs Act (TCJA) (as a percent)		(0.034)	(0.388)
Excess tax benefit on share-based compensation (as a percent)	(1.70%)	(6.70%)	(6.90%)
Effective rate reduction due to dividend received (as a percent)	(0.40%)	(1.10%)	(2.40%)
Effective rate reduction due to dividend paid to ESOP (as a percent)	(0.50%)	(1.80%)	(3.40%)
Effective rate reduction due to tax exempt interest income (as a percent)	(0.50%)	(2.70%)	(5.50%)
Effective rate reduction due to unconsolidated investee dividends (as a percent)	(0.80%)		(1.60%)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other (as a percent)	0.70%	0.60%	0.30%
Effective rate reduction due to other items, net (as a percent)	(0.10%)	(0.90%)	(0.90%)
Effective Income Tax Rate Reconciliation, Percent, Total	17.70%	5.00%	(24.20%)
Income tax expense	$ 41,092,000	$ 3,402,000	$ (20,439,000)
Effective tax rates (as a percent)	17.70%	5.00%	(24.20%)
Capital gains rate (as a percent)	21.00%
Tax Cuts and Jobs Act, Measurement Period Adjustment, Income Tax Expense (Benefit)		$ 2,300,000	$ (32,800,000)
Tax Cuts and Jobs Act, Measurement Period Adjustment, Increase (Decrease) in Effective Tax Rate			(0.388)
Dividend received	$ 13,200,000	$ 9,900,000	$ 0
Lower tax rate (as a percent)	7.40%	7.40%
Effective rate reduction due to dividends paid to ESOP (as a percent)	0.50%	1.80%	3.40%
Expected effective tax rate when deferred items reverse in future years (as a percent)	21.00%
Federal and state income taxes paid	$ 25,600,000	$ 16,400,000	$ 10,400,000

EMPLOYEE BENEFITS - Stock Owner

EMPLOYEE BENEFITS - Stock Ownership and Incentive Plans (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Stock Ownership, 401(K) And Deferred Compensation Plan
Annual expenses for incentive plans	$ 30.1	$ 11.9	$ 19.7
ESOP and 401(k) Plans
Employee Stock Ownership, 401(K) And Deferred Compensation Plan
Vesting period of profit sharing contributions	3 years
Expenses recognized	$ 15.7	$ 8.8	$ 12.5
Employee Stock Ownership Plan (ESOP)
Employee Stock Ownership, 401(K) And Deferred Compensation Plan
Shares purchased under defined contribution plan	60,768	98,717	124,186
Average price of shares purchased (in dollars per share)	$ 69.99	$ 62.80	$ 58.02
Aggregate price of shares purchased	$ 4.3	$ 6.2	$ 7.2
Shares held by the ESOP	2,758,290
Employee 401(k) Plans
Employee Stock Ownership, 401(K) And Deferred Compensation Plan
Employer contribution as a percent of eligible compensation	3.00%
Vesting percentage in basic and voluntary contributions	100.00%
Deferred compensation plan
Employee Stock Ownership, 401(K) And Deferred Compensation Plan
Shares purchased under defined contribution plan	6,569	7,049	7,464
Average price of shares purchased (in dollars per share)	$ 81.77	$ 68.36	$ 58.66
Aggregate price of shares purchased	$ 0.5	$ 0.5	$ 0.4
Assets held under trust	$ 44.5

EMPLOYEE BENEFITS - Stock Optio

EMPLOYEE BENEFITS - Stock Options and Stock Plans (Details) - USD ($)	1 Months Ended			12 Months Ended			24 Months Ended	36 Months Ended	56 Months Ended	60 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2019	May 06, 2015	May 07, 2015
Weighted Number of Options Outstanding
Outstanding options at the beginning of the period (in shares)				1,964,880	2,257,015	2,207,110	2,257,015	2,207,110
Options granted (in shares)	251,400	330,750	384,750	356,900	432,000	482,375
Options exercised (in shares)				(533,940)	(705,785)	(390,870)
Options canceled/forfeited (in shares)				(120,550)	(18,350)	(41,600)
Outstanding options at the end of the period (in shares)				1,667,290	1,964,880	2,257,015	1,667,290	1,667,290	1,667,290
Exercisable options at the end of the period (in shares)				642,365	724,730	975,055	642,365	642,365	642,365
Weighted Average Exercise Price
Outstanding options at the beginning of the period (in dollars per share)				$ 54.24	$ 46.80	$ 40.90	$ 46.80	$ 40.90
Options granted (in dollars per share)				82.63	64.91	57.12
Options exercised (in dollars per share)				45.96	36.81	26.07
Options canceled/forfeited (in dollars per share)				60.48	60.84	48.30
Outstanding options at the end of the period (in dollars per share)				62.52	54.24	46.80	62.52	62.52	$ 62.52
Exercisable options at the end of the period (in dollars per share)				$ 53.93	$ 46.62	$ 38.66	$ 53.93	$ 53.93	$ 53.93
Weighted Average Remaining Contractual Life
Weighted-average remaining contractual term of options outstanding				5 years 2 months 12 days	5 years 3 months	4 years 10 months 17 days
Weighted-average remaining contractual term of exercisable options				3 years 9 months 18 days	3 years 9 months 14 days	3 years 3 months
Aggregate Intrinsic Value
Options exercised (in dollars)				$ 20,033,000	$ 24,304,000	$ 12,779,000
Outstanding options at the end of the period (in dollars)				46,051,000	29,317,000	32,620,000	$ 46,051,000	$ 46,051,000	$ 46,051,000
Exercisable options at the end of the period (in dollars)				$ 23,197,000	$ 16,212,000	$ 21,780,000	23,197,000	23,197,000	23,197,000
Weighted-average fair value of options granted (in dollars per share)	$ 13.65	$ 10.31	$ 7.91	$ 13.49	$ 10.58	$ 8
Stock-based compensation expenses (in dollars)				$ 4,500,000	$ 4,500,000	$ 4,400,000
Income tax benefit from stock-based compensation (in dollars)				900,000	900,000	1,500,000
Unrecognized stock-based compensation expense (in dollars)				$ 4,800,000	$ 5,600,000	$ 5,700,000	$ 4,800,000	$ 4,800,000	$ 4,800,000
Weighted average grant date assumptions and weighted average fair value
Weighted-average fair value of grants (in dollars per share)	$ 13.65	$ 10.31	$ 7.91	$ 13.49	$ 10.58	$ 8
Risk-free interest rates (as a percent)				2.26%	2.72%	1.90%
Dividend yield (as a percent)				2.69%	2.98%	3.60%
Expected volatility (as a percent)				22.71%	22.87%	22.95%
Expected option life				4 years 11 months 15 days	5 years 25 days	5 years 18 days
Long Term Incentive Plan
Stock options and stock plans
Award vesting period				5 years
Term of options				8 years
Age and period of service of the participant to be eligible for retirement				75 years
RLI Corp. Long-Term Incentive Plan (2015 LTIP)
Stock options and stock plans
Shares authorized for grant				4,000,000			4,000,000	4,000,000	4,000,000
Stock options granted to date (in shares)									2,282,460
Weighted Number of Options Outstanding
Options granted (in shares)				378,830
RLI Corp. Long-Term Incentive Plan 2010
Stock options and stock plans
Shares authorized for grant											4,000,000
Stock options granted to date (in shares)										2,878,000
Restricted Stock Units (RSUs) | Outside director
Aggregate Intrinsic Value
Stock-based compensation expenses (in dollars)				$ 600,000
Restricted Stock Units (RSUs) | RLI Corp. Long-Term Incentive Plan (2015 LTIP)
Stock options and stock plans
Award vesting period				3 years
Age and period of service of the participant to be eligible for retirement				75 years
Aggregate Intrinsic Value
Stock-based compensation expenses (in dollars)				$ 900,000	$ 600,000	$ 400,000
Unrecognized stock-based compensation expense (in dollars)				$ 900,000			$ 900,000	$ 900,000	$ 900,000
Weighted average grant date assumptions and weighted average fair value
RSUs Granted				15,275				45,350
RSUs Outstanding				43,681			43,681	43,681	43,681
Restricted Stock Units (RSUs) | RLI Corp. Long-Term Incentive Plan (2015 LTIP) | Outside director
Stock options and stock plans
Award vesting period							1 year
Aggregate Intrinsic Value
Stock-based compensation expenses (in dollars)				$ 600,000	$ 300,000
Unrecognized stock-based compensation expense (in dollars)				$ 200,000			$ 200,000	$ 200,000	$ 200,000
Weighted average grant date assumptions and weighted average fair value
RSUs Granted				6,655			15,085
RSUs Outstanding				6,162			6,162	6,162	6,162
Grant date fair value of RSUs							$ 50,000

STATUTORY INFORMATION AND DIV_3

STATUTORY INFORMATION AND DIVIDEND RESTRICTIONS (Details)	12 Months Ended
	Dec. 31, 2019USD ($)company	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Statutory information and dividend restrictions
Number of insurance companies | company	3
Remaining unrestricted equity, liquid assets	$ 45,900,000
Equity	995,388,000	$ 806,842,000	$ 853,598,000	$ 823,572,000
Fair Value of Investment in Affiliate Included in Statutory Surplus	190,900,000	132,800,000	106,900,000
Cost Basis of Investment in Affiliate Included in Statutory Surplus	64,600,000
Insurance subsidiaries
Selected information for insurance subsidiaries
Consolidated net income, statutory basis	129,625,000	135,791,000	72,889,000
Consolidated surplus, statutory basis	1,029,671,000	829,775,000	864,554,000
RLI Ins.
Statutory information and dividend restrictions
Authorized control level RBC	191,000,000	170,900,000	157,700,000
Selected information for insurance subsidiaries
Consolidated surplus, statutory basis	$ 1,029,700,000	829,800,000	864,600,000
Dividend restriction as percentage of policyholder surplus	10.00%
Payments of Ordinary Dividends	$ 59,000,000	13,000,000	107,000,000
Extraordinary dividend paid after seeking and receiving approval from the Illinois regulatory authorities	0	$ 110,000,000	$ 0
Non restricted net assets	$ 65,300,000

COMMITMENTS AND CONTINGENT LI_2

COMMITMENTS AND CONTINGENT LIABILITIES (Details) $ in Millions	Dec. 31, 2019USD ($)
Other Assets
Qualified Affordable Housing Project Investments, Commitment	$ 8.6
Investment In Low Income Housing Tax Credit Partnership Net Of Amortization
Other Assets
Qualified Affordable Housing Project Investments, Commitment	8.6
Investment in Private Funds
Other Assets
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 15.5

LEASES - Components of Lease Ex

LEASES - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases
Expense associated with operating leases		$ 6,900	$ 6,800
Operating Lease Cost	$ 5,772
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	5,711
Right-of-use assets obtained in exchange for new operating lease liabilities	1,388
Reduction to right-of-use asset resulting from reduction to lease liability	1,279
Operating lease right-of-use assets	$ 22,335
Operating lease, right-of-use asset, Statement of Financial Position	us-gaap:OtherAssets
Operating Lease Liabilities	$ 24,475
Operating lease liability, Statement of Financial Position	us-gaap:OtherLiabilities
Weighted-average remaining lease term - operating leases	4 years 8 months 8 days
Weighted-average discount rate - operating leases	2.33%
Minimum
Leases
Remaining lease terms - operating leases	1 year
Maximum
Leases
Remaining lease terms - operating leases	15 years

LEASES - Future Minimum Lease P

LEASES - Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Future minimum lease payments under non-cancellable leases
2020	$ 5,983
2021	5,968
2022	5,904
2023	4,386
2024	2,334
Thereafter	1,366
Total future minimum lease payments	25,941
Less imputed interest	(1,466)
Total operating lease liability	$ 24,475
2019		$ 5,911
2020		6,019
2021		5,924
2022		5,884
2023		4,459
Thereafter		3,968
Total future minimum lease payments		$ 32,165

OPERATING SEGMENT INFORMATION -

OPERATING SEGMENT INFORMATION - Summary of Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
REVENUES
Net premiums earned	$ 215,626	$ 211,255	$ 207,541	$ 204,689	$ 204,002	$ 200,815	$ 196,522	$ 190,027	$ 839,111	$ 791,366	$ 737,937
Net investment income	17,775	17,532	16,998	16,565	16,962	16,314	14,577	14,232	68,870	62,085	54,876
Net realized gains	477	3,211	4,764	9,068	15,507	18,647	20,849	8,404	17,520	63,407	4,411
Net unrealized gains (losses) on equity securities	30,876	4,906	8,810	33,498	(64,200)	4,848	(12,611)	(26,772)	78,090	(98,735)
Consolidated revenue									1,003,591	818,123	797,224
INSURANCE EXPENSES
Loss and settlement expenses									413,416	428,193	401,584
Policy acquisition costs									288,697	267,738	252,515
Other insurance expenses									69,430	53,803	56,994
Insurance expenses									771,543	749,734	711,093
NET EARNINGS
Net underwriting income									67,568	41,632	26,844
Net investment income	17,775	17,532	16,998	16,565	16,962	16,314	14,577	14,232	68,870	62,085	54,876
Net realized gains	477	3,211	4,764	9,068	15,507	18,647	20,849	8,404	17,520	63,407	4,411
Net unrealized gains (losses) on equity securities	30,876	4,906	8,810	33,498	(64,200)	4,848	(12,611)	(26,772)	78,090	(98,735)
General corporate expense and interest on debt									(20,274)	(16,864)	(18,766)
Equity in earnings of unconsolidated investees									20,960	16,056	17,224
Earnings before income taxes	63,218	38,947	48,828	81,741	(32,708)	46,349	39,562	14,378	232,734	67,581	84,589
Income tax expense									41,092	3,402	(20,439)
Net earnings	$ 53,378	$ 32,324	$ 40,467	$ 65,473	$ (20,660)	$ 39,372	$ 33,251	$ 12,216	$ 191,642	64,179	105,028
Maui Jim Inc.
Segment reporting information
Ownership percentage	40.00%								40.00%
Prime Holdings Insurance Services, Inc. (Prime)
Segment reporting information
Ownership percentage	23.00%								23.00%
Casualty segment
REVENUES
Net premiums earned									$ 558,458	523,472	478,603
INSURANCE EXPENSES
Loss and settlement expenses									330,156	329,763	305,679
Policy acquisition costs									166,499	151,007	136,135
Other insurance expenses									41,202	31,562	32,885
NET EARNINGS
Net underwriting income									20,601	11,140	3,904
Property segment
REVENUES
Net premiums earned									164,022	149,261	138,346
INSURANCE EXPENSES
Loss and settlement expenses									73,614	83,822	85,027
Policy acquisition costs									55,986	51,830	51,070
Other insurance expenses									16,279	12,725	14,108
NET EARNINGS
Net underwriting income									18,143	884	(11,859)
Surety segment
REVENUES
Net premiums earned									116,631	118,633	120,988
INSURANCE EXPENSES
Loss and settlement expenses									9,646	14,608	10,878
Policy acquisition costs									66,212	64,901	65,310
Other insurance expenses									11,949	9,516	10,001
NET EARNINGS
Net underwriting income									$ 28,824	$ 29,608	$ 34,799

OPERATING SEGMENT INFORMATION_2

OPERATING SEGMENT INFORMATION - Revenue by Product (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue by major product
Net premiums earned	$ 215,626	$ 211,255	$ 207,541	$ 204,689	$ 204,002	$ 200,815	$ 196,522	$ 190,027	$ 839,111	$ 791,366	$ 737,937
Casualty segment
Revenue by major product
Net premiums earned									558,458	523,472	478,603
Casualty segment | Commercial excess and personal umbrella
Revenue by major product
Net premiums earned									140,483	124,350	115,543
Casualty segment | General liability
Revenue by major product
Net premiums earned									98,880	93,928	90,283
Casualty segment | Transportation
Revenue by major product
Net premiums earned									83,213	81,053	78,061
Casualty segment | Professional services
Revenue by major product
Net premiums earned									81,329	79,951	78,508
Casualty segment | Small commercial
Revenue by major product
Net premiums earned									55,701	51,519	49,601
Casualty segment | Executive products
Revenue by major product
Net premiums earned									27,088	21,326	18,086
Casualty segment | Other casualty
Revenue by major product
Net premiums earned									71,764	71,345	48,521
Property segment
Revenue by major product
Net premiums earned									164,022	149,261	138,346
Property segment | Marine
Revenue by major product
Net premiums earned									74,887	59,795	50,931
Property segment | Commercial property
Revenue by major product
Net premiums earned									68,310	71,501	63,117
Property segment | Specialty Personal
Revenue by major product
Net premiums earned									19,316	16,901	20,793
Property segment | Other property
Revenue by major product
Net premiums earned									1,509	1,064	3,505
Surety segment
Revenue by major product
Net premiums earned									116,631	118,633	120,988
Surety segment | Miscellaneous
Revenue by major product
Net premiums earned									44,721	46,968	47,237
Surety segment | Commercial
Revenue by major product
Net premiums earned									43,553	43,469	45,178
Surety segment | Contract
Revenue by major product
Net premiums earned									$ 28,357	$ 28,196	$ 28,573

UNAUDITED INTERIM FINANCIAL I_3

UNAUDITED INTERIM FINANCIAL INFORMATION (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
UNAUDITED INTERIM FINANCIAL INFORMATION
Net premiums earned	$ 215,626	$ 211,255	$ 207,541	$ 204,689	$ 204,002	$ 200,815	$ 196,522	$ 190,027	$ 839,111	$ 791,366	$ 737,937
Net investment income	17,775	17,532	16,998	16,565	16,962	16,314	14,577	14,232	68,870	62,085	54,876
Net realized gains	477	3,211	4,764	9,068	15,507	18,647	20,849	8,404	17,520	63,407	4,411
Equity Securities, FV-NI, Unrealized Gain (Loss)	30,876	4,906	8,810	33,498	(64,200)	4,848	(12,611)	(26,772)	78,090	(98,735)
Earnings before income taxes	63,218	38,947	48,828	81,741	(32,708)	46,349	39,562	14,378	232,734	67,581	84,589
Net earnings	$ 53,378	$ 32,324	$ 40,467	$ 65,473	$ (20,660)	$ 39,372	$ 33,251	$ 12,216	$ 191,642	$ 64,179	$ 105,028
Basic earnings per share (in dollars per share)	$ 1.19	$ 0.72	$ 0.91	$ 1.47	$ (0.46)	$ 0.89	$ 0.75	$ 0.28	$ 4.28	$ 1.45	$ 2.39
Diluted earnings per share (in dollars per share)	$ 1.18	$ 0.71	$ 0.89	$ 1.46	$ (0.46)	$ 0.88	$ 0.74	$ 0.27	$ 4.23	$ 1.43	$ 2.36

SCHEDULE I-SUMMARY OF INVESTM_2

SCHEDULE I-SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) $ in Thousands	Dec. 31, 2019USD ($)
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	$ 2,294,337
Fair Value	2,560,360
Amount at which shown in the balance sheet	2,560,360
Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	1,915,278
Fair Value	1,983,086
Amount at which shown in the balance sheet	1,983,086
Debt securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	1,915,278
Fair Value	1,983,086
Amount at which shown in the balance sheet	1,983,086
U.S. government | Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	186,699
Fair Value	193,661
Amount at which shown in the balance sheet	193,661
U.S. Agency | Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	36,535
Fair Value	38,855
Amount at which shown in the balance sheet	38,855
Non-U.S. govt. & agency | Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	7,333
Fair Value	7,628
Amount at which shown in the balance sheet	7,628
Agency MBS | Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	411,808
Fair Value	420,165
Amount at which shown in the balance sheet	420,165
ABS/CMBS/MBS | Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	222,832
Fair Value	224,870
Amount at which shown in the balance sheet	224,870
Corporate Debt | Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	659,640
Fair Value	692,067
Amount at which shown in the balance sheet	692,067
Municipal | Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	390,431
Fair Value	405,840
Amount at which shown in the balance sheet	405,840
Equity securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	262,131
Fair Value	460,630
Amount at which shown in the balance sheet	460,630
Ind Misc & all other
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	139,588
Fair Value	250,831
Amount at which shown in the balance sheet	250,831
ETFs (Ind/misc)
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	122,543
Fair Value	209,799
Amount at which shown in the balance sheet	209,799
Cash and Short-term Investments
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	46,203
Fair Value	46,203
Amount at which shown in the balance sheet	46,203
Other Invested Assets
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	70,725
Fair Value	70,441
Amount at which shown in the balance sheet	$ 70,441

SCHEDULE II-CONDENSED FINANCI_2

SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash	$ 46,203	$ 30,140
Investments in unconsolidated investee, at equity value	103,836	94,967
Fixed income:
Available-for-sale fixed income	1,983,086	1,760,515
Property and equipment, at cost, net of accumulated depreciation of $1,562 in 2019 and $1,494 in 2018	53,121	54,692
TOTAL ASSETS	3,545,721	3,105,065
Liabilities:
Bonds payable, long-term debt	149,302	149,115
TOTAL LIABILITIES	2,550,333	2,298,223
Shareholders' Equity
Common stock ($0.01 par value, authorized 100,000,000 shares, issued 67,799,229 shares in 2019 and 67,434,257 shares in 2018, and outstanding 44,869,015 shares in 2018 and 44,504,043 shares in 2018)	678	674
Paid-in capital	321,190	305,660
Accumulated other comprehensive earnings (loss)	52,473	(14,572)
Retained earnings	1,014,046	908,079
Deferred compensation	7,980	8,354
Treasury shares at cost (22,930,214 shares in 2019 and 2018)	(400,979)	(401,353)
TOTAL SHAREHOLDERS' EQUITY	995,388	806,842	$ 853,598	$ 823,572
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,545,721	3,105,065
PARENT COMPANY
ASSETS
Cash	350	3,214
Investments in subsidiaries, at equity value	1,034,679	828,806
Investments in unconsolidated investee, at equity value	79,597	79,521
Fixed income:
Available-for-sale fixed income	45,538	59,878
Property and equipment, at cost, net of accumulated depreciation of $1,562 in 2019 and $1,494 in 2018	1,846	1,914
Income taxes receivable - current	842
Other assets	400	547
TOTAL ASSETS	1,163,252	973,880
Liabilities:
Accounts payable, affiliates	1,310	130
Income taxes payable--current		32
Income taxes payable--deferred	14,578	15,081
Bonds payable, long-term debt	149,302	149,115
Interest payable, long-term debt	2,153	2,153
Other liabilities	521	527
TOTAL LIABILITIES	167,864	167,038
Shareholders' Equity
Common stock ($0.01 par value, authorized 100,000,000 shares, issued 67,799,229 shares in 2019 and 67,434,257 shares in 2018, and outstanding 44,869,015 shares in 2018 and 44,504,043 shares in 2018)	678	674
Paid-in capital	321,190	305,660
Accumulated other comprehensive earnings (loss)	52,473	(14,572)
Retained earnings	1,014,046	908,079
Deferred compensation	7,980	8,354
Treasury shares at cost (22,930,214 shares in 2019 and 2018)	(400,979)	(401,353)
TOTAL SHAREHOLDERS' EQUITY	995,388	806,842
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 1,163,252	$ 973,880

SCHEDULE II-CONDENSED FINANCI_3

SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - Balance Sheets Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONDENSED BALANCE SHEETS (Parenthetical)
Available-for-sale, amortized cost	$ 1,915,278	$ 1,776,465
Property and equipment, accumulated depreciation	$ 62,703	$ 54,275
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 1
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	67,799,229	67,434,257
Common stock, shares outstanding (in shares)	44,869,015	44,504,043
Treasury stock, shares (in shares)	22,930,214	22,930,214
PARENT COMPANY
CONDENSED BALANCE SHEETS (Parenthetical)
Available-for-sale, amortized cost	$ 42,747	$ 58,812
Property and equipment, accumulated depreciation	$ 1,562	$ 1,494
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	67,799,229	67,434,257
Common stock, shares outstanding (in shares)	44,869,015	44,504,043
Treasury stock, shares (in shares)	22,930,214	22,930,214

SCHEDULE II-CONDENSED FINANCI_4

SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - Statements of Earnings and Comprehensive Earnings (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONDENSED STATEMENTS OF EARNINGS AND COMPREHENSIVE EARNINGS
Net investment income	$ 17,775	$ 17,532	$ 16,998	$ 16,565	$ 16,962	$ 16,314	$ 14,577	$ 14,232	$ 68,870	$ 62,085	$ 54,876
Net realized gains									17,520	63,624	6,970
Equity in earnings of unconsolidated investees									20,960	16,056	17,224
Interest expense on debt									(7,588)	(7,437)	(7,426)
Earnings before income taxes	63,218	38,947	48,828	81,741	(32,708)	46,349	39,562	14,378	232,734	67,581	84,589
Income tax benefit									41,092	3,402	(20,439)
Net earnings	$ 53,378	$ 32,324	$ 40,467	$ 65,473	$ (20,660)	$ 39,372	$ 33,251	$ 12,216	191,642	64,179	105,028
Unrealized gains (losses) on securities:
Other comprehensive earnings (loss), net of tax									67,045	(33,997)	35,309
Comprehensive earnings									258,687	30,182	140,337
PARENT COMPANY
CONDENSED STATEMENTS OF EARNINGS AND COMPREHENSIVE EARNINGS
Net investment income									1,656	648	647
Net realized gains									463	(142)	(36)
Equity in earnings of unconsolidated investees									13,592	12,471	14,436
Selling, general and administrative expenses									(12,686)	(9,427)	(11,340)
Interest expense on debt									(7,588)	(7,437)	(7,426)
Earnings before income taxes									(4,563)	(3,887)	(3,719)
Income tax benefit									(4,989)	(2,359)	(16,601)
Net earnings (loss) before equity in net earnings of subsidiaries									426	(1,528)	12,882
Equity in net earnings of subsidiaries									191,216	65,707	92,146
Net earnings									191,642	64,179	105,028
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during the period									1,727	710	21
Less: reclassification adjustment for losses (gains) included in net earnings									(365)	112	6
Other Comprehensive Income (Loss), Net of Tax, Total									1,362	822	27
Equity in other comprehensive earnings (loss) of subsidiaries/investees									65,683	(34,819)	35,282
Other comprehensive earnings (loss), net of tax									67,045	(33,997)	35,309
Comprehensive earnings									$ 258,687	$ 30,182	$ 140,337

SCHEDULE II-CONDENSED FINANCI_5

SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - Statements of Cash Flows (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Earnings (loss) before equity in net earnings of subsidiaries									$ 191,642,000	$ 64,179,000	$ 105,028,000
Adjustments to reconcile net losses to net cash provided by (used in) operating activities:
Net realized gains (losses)	$ (477,000)	$ (3,211,000)	$ (4,764,000)	$ (9,068,000)	$ (15,507,000)	$ (18,647,000)	$ (20,849,000)	$ (8,404,000)	(17,520,000)	(63,407,000)	(4,411,000)
Depreciation									8,164,000	7,042,000	6,944,000
Other items, net									25,341,000	6,171,000	16,368,000
Changes in investment in unconsolidated investees:
Undistributed earnings									(20,960,000)	(16,056,000)	(17,224,000)
Dividends received									13,200,000	9,900,000	0
Net Cash Provided by Operating Activities									276,917,000	217,102,000	197,525,000
Purchase of:
Fixed income, available-for-sale									(539,726,000)	(725,675,000)	(430,727,000)
Property and equipment									(6,955,000)	(6,087,000)	(9,238,000)
Sale of:
Fixed income, available-for-sale									196,558,000	395,019,000	168,760,000
Property and equipment										167,000	128,000
Call or maturity of:
Fixed income, available-for-sale									201,383,000	187,380,000	195,617,000
Payments for (Proceeds from) Short-term Investments [Abstract]
Net proceeds from sale (purchase) of short-term investments									11,550,000	(1,570,000)	(4,965,000)
Net cash used in investing activities									(184,753,000)	(134,209,000)	(81,212,000)
Cash flows from financing activities
Proceeds from stock option exercises									9,490,000	6,076,000	3,502,000
Net cash used in financing activities									(76,101,000)	(77,024,000)	(110,311,000)
Net increase (decrease) in cash									16,063,000	5,869,000	6,002,000
Cash at the beginning of the period				30,140,000				24,271,000	30,140,000	24,271,000	18,269,000
Cash at the end of the period	46,203,000				30,140,000				46,203,000	30,140,000	24,271,000
Interest paid on outstanding debt									7,300,000	7,300,000	7,300,000
PARENT COMPANY
Cash flows from operating activities
Earnings (loss) before equity in net earnings of subsidiaries									426,000	(1,528,000)	12,882,000
Adjustments to reconcile net losses to net cash provided by (used in) operating activities:
Net realized gains (losses)									(463,000)	142,000	36,000
Depreciation									68,000	68,000	77,000
Other items, net									2,487,000	(471,000)	595,000
Change in:
Affiliate balances receivable/payable									1,180,000	1,187,000	(930,000)
Federal income taxes									(1,673,000)	3,430,000	(6,874,000)
Changes in investment in unconsolidated investees:
Undistributed earnings									(13,592,000)	(12,471,000)	(14,436,000)
Dividends received									13,200,000	9,900,000
Net Cash Provided by Operating Activities									1,633,000	257,000	(8,650,000)
Purchase of:
Fixed income, available-for-sale									(2,507,000)	(73,812,000)	(5,773,000)
Sale of:
Fixed income, available-for-sale									14,273,000	12,056,000	24,771,000
Property and equipment											128,000
Call or maturity of:
Fixed income, available-for-sale									29,501,000	75,662,000	3,499,000
Payments for (Proceeds from) Short-term Investments [Abstract]
Net proceeds from sale (purchase) of short-term investments										70,000	(47,000)
Cash dividends received-subsidiaries									34,003,000	73,363,000	107,000,000
Net cash used in investing activities									75,270,000	87,339,000	129,578,000
Cash flows from financing activities
Proceeds from stock option exercises									9,490,000	6,076,000	3,502,000
Cash dividends paid									(93,315,000)	(90,662,000)	(124,247,000)
Proceeds from (Payments for) Other Financing Activities									4,058,000
Net cash used in financing activities									(79,767,000)	(84,586,000)	(120,745,000)
Net increase (decrease) in cash									(2,864,000)	3,010,000	183,000
Cash at the beginning of the period				$ 3,214,000				$ 204,000	3,214,000	204,000	21,000
Cash at the end of the period	$ 350,000				$ 3,214,000				350,000	3,214,000	204,000
Interest paid on outstanding debt									$ 7,300,000	$ 7,300,000	$ 7,300,000

SCHEDULE III-SUPPLEMENTARY IN_2

SCHEDULE III-SUPPLEMENTARY INSURANCE INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplementary insurance information
Deferred policy acquisition costs	$ 85,044	$ 84,934	$ 77,716
Unpaid losses and settlement expenses, gross	1,574,352	1,461,348	1,271,503
Unearned premiums, gross	540,213	496,505	451,449
Net premiums earned	839,111	791,366	737,937
Incurred losses and settlement expenses
Current accident year	488,700	478,143	440,452
Prior accident years	(75,284)	(49,950)	(38,868)
Policy acquisition costs	288,697	267,738	252,515
Other operating expenses	69,430	53,803	56,994
Net premiums written	860,337	823,175	749,854
Casualty segment
Supplementary insurance information
Deferred policy acquisition costs	47,805	50,040	44,358
Unpaid losses and settlement expenses, gross	1,435,619	1,283,204	1,127,787
Unearned premiums, gross	354,118	330,836	296,751
Net premiums earned	558,458	523,472	478,603
Incurred losses and settlement expenses
Current accident year	392,653	363,015	323,141
Prior accident years	(62,497)	(33,252)	(17,462)
Policy acquisition costs	166,499	151,007	136,135
Other operating expenses	41,202	31,562	32,885
Net premiums written	564,979	547,177	494,649
Property segment
Supplementary insurance information
Deferred policy acquisition costs	17,057	14,090	13,029
Unpaid losses and settlement expenses, gross	100,000	134,822	107,304
Unearned premiums, gross	116,624	93,032	84,010
Net premiums earned	164,022	149,261	138,346
Incurred losses and settlement expenses
Current accident year	78,075	94,635	97,161
Prior accident years	(4,461)	(10,813)	(12,134)
Policy acquisition costs	55,986	51,830	51,070
Other operating expenses	16,279	12,725	14,108
Net premiums written	181,974	155,601	137,031
Surety segment
Supplementary insurance information
Deferred policy acquisition costs	20,182	20,804	20,329
Unpaid losses and settlement expenses, gross	38,733	43,322	36,412
Unearned premiums, gross	69,471	72,637	70,688
Net premiums earned	116,631	118,633	120,988
Incurred losses and settlement expenses
Current accident year	17,972	20,493	20,150
Prior accident years	(8,326)	(5,885)	(9,272)
Policy acquisition costs	66,212	64,901	65,310
Other operating expenses	11,949	9,516	10,001
Net premiums written	$ 113,384	$ 120,397	$ 118,174

SCHEDULE IV-REINSURANCE (Detail

SCHEDULE IV-REINSURANCE (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
RLI Insurance Group Premiums earned
Direct amount									$ 981,121	$ 896,234	$ 835,118
Ceded to other companies									182,183	146,794	129,702
Assumed from other companies									40,173	41,926	32,521
Net amount	$ 215,626	$ 211,255	$ 207,541	$ 204,689	$ 204,002	$ 200,815	$ 196,522	$ 190,027	$ 839,111	$ 791,366	$ 737,937
Percentage of amount assumed to net									4.80%	5.30%	4.40%
Casualty segment
RLI Insurance Group Premiums earned
Direct amount									$ 641,159	$ 578,643	$ 536,085
Ceded to other companies									122,452	96,639	86,190
Assumed from other companies									39,751	41,468	28,708
Net amount									$ 558,458	$ 523,472	$ 478,603
Percentage of amount assumed to net									7.10%	7.90%	6.00%
Property segment
RLI Insurance Group Premiums earned
Direct amount									$ 217,657	$ 193,855	$ 172,668
Ceded to other companies									53,810	44,634	37,607
Assumed from other companies									175	40	3,285
Net amount									$ 164,022	$ 149,261	$ 138,346
Percentage of amount assumed to net									0.10%	0.00%	2.40%
Surety segment
RLI Insurance Group Premiums earned
Direct amount									$ 122,305	$ 123,736	$ 126,365
Ceded to other companies									5,921	5,521	5,905
Assumed from other companies									247	418	528
Net amount									$ 116,631	$ 118,633	$ 120,988
Percentage of amount assumed to net									0.20%	0.40%	0.40%

SCHEDULE V-VALUATION AND QUAL_2

SCHEDULE V-VALUATION AND QUALIFYING ACCOUNTS (Details) - Allowance for uncollectible reinsurance - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for uncollectible reinsurance
Balance at beginning of period	$ 25,911	$ 25,911	$ 25,911
Amounts charged to expense	(647)
Amounts recovered (written off)	(198)
Balance at end of period	$ 25,066	$ 25,911	$ 25,911

SCHEDULE VI-SUPPLEMENTARY INF_2

SCHEDULE VI-SUPPLEMENTARY INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Claims and claim adjustment expenses incurred related to:
Current accident year	$ 488,700	$ 478,143	$ 440,452
Prior accident years	(75,284)	(49,950)	(38,868)
Amortization of deferred acquisition costs	288,697	267,738	252,515
Consolidated property-casualty insurance operations
SUPPLEMENTARY INFORMATION CONCERNING PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs	85,044	84,934	77,716
Claims and claim adjustment expense reserves	1,574,352	1,461,348	1,271,503
Unearned premiums, gross	540,213	496,505	451,449
Net premiums earned	839,111	791,366	737,937
Net investment income	68,870	62,085	54,876
Claims and claim adjustment expenses incurred related to:
Current accident year	488,700	478,143	440,452
Prior accident years	(75,284)	(49,950)	(38,868)
Amortization of deferred acquisition costs	288,697	267,738	252,515
Paid claims and claims adjustment expenses	319,930	301,356	283,185
Net premiums written	$ 860,337	$ 823,175	$ 749,854