James River (JRVR) 10-K 26 Feb 21 2020 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 23, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-36777
Entity Registrant Name	JAMES RIVER GROUP HOLDINGS, LTD.
Entity Incorporation, State or Country Code	D0
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		30,765,510
Amendment Flag	false
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Entity Tax Identification Number	98-0585280
Entity Address, Address Line Three	Wellesley House
Entity Address, Address Line Two	2nd Floor
Entity Address, Address Line One	90 Pitts Bay Road
Entity Address, City or Town	Pembroke
Entity Address, Postal Zip Code	HM08
Entity Address, Country	BM
City Area Code	441
Local Phone Number	278-4580
Title of 12(b) Security	Common Shares, par value $0.0002 per share
Trading Symbol	JRVR
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Public Float			$ 1,332,336,690
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE: Portions of the James River Group Holdings, Ltd. Proxy Statement to be filed with the Securities and Exchange Commission within 120 days after the year covered by this Form 10-K with respect to the 2021 Annual General Meeting of Shareholders are incorporated by reference into Part III hereof.
Entity Central Index Key	0001620459

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Invested assets:
Fixed maturity securities, available-for-sale, at fair value (amortized cost: 2020 – $1,690,890; 2019 – $1,398,533)	$ 1,783,642	$ 1,433,626
Equity securities, at fair value (cost: 2020 – $81,698; 2019 – $73,244)	88,975	80,735
Bank loan participations (2020: at fair value; 2019: held-for-investment, at amortized cost, net of allowance)	147,604
Bank loan participations (2020: at fair value; 2019: held-for-investment, at amortized cost, net of allowance)		260,864
Short-term investments	130,289	156,925
Other invested assets	46,548	61,210
Total invested assets	2,197,058	1,993,360
Cash and cash equivalents	162,260	206,912
Restricted cash equivalents	859,920	1,199,164
Accrued investment income	10,980	13,597
Premiums receivable and agents’ balances, net	369,577	369,462
Reinsurance recoverable on unpaid losses, net	805,684	668,045
Reinsurance recoverable on paid losses	46,118	33,221
Prepaid reinsurance premiums	243,741	178,976
Deferred policy acquisition costs	62,953	62,006
Intangible assets, net	36,402	36,940
Goodwill	181,831	181,831
Deferred tax assets, net	0	664
Income taxes receivable	4,433	0
Other assets	82,115	80,227
Total assets	5,063,072	5,024,405
Liabilities:
Reserve for losses and loss adjustment expenses	2,192,080	2,045,506
Unearned premiums	630,371	524,377
Payables to reinsurers	110,431	108,059
Funds held	859,920	1,199,164
Senior debt	262,300	158,300
Junior subordinated debt	104,055	104,055
Accrued expenses	55,989	58,416
Deferred tax liabilities, net	1,105	0
Income taxes payable	0	1,483
Other liabilities	51,213	46,464
Total liabilities	4,267,464	4,245,824
Commitments and contingent liabilities
Shareholders’ equity:
Common Shares – $0.0002 par value; 200,000,000 shares authorized. 2020 and 2019: 30,649,261 and 30,424,391 shares issued and outstanding, respectively	6	6
Preferred Shares – 2020 and 2019: $0.00125 par value; 20,000,000 shares authorized; no shares issued and outstanding	0	0
Additional paid-in capital	664,476	657,875
Retained earnings	49,227	89,586
Accumulated other comprehensive income	81,899	31,114
Total shareholders’ equity	795,608	778,581
Total liabilities and shareholders’ equity	$ 5,063,072	$ 5,024,405

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Available-for-sale debt securities, amortized cost (in dollars)	$ 1,690,890	$ 1,398,533
Equity securities, amortized cost	$ 81,698	$ 73,244
Common stock, par value (in dollars per share)	$ 0.0002	$ 0.0002
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	30,649,261	30,424,391
Common stock, shares outstanding	30,649,261	30,424,391
Preferred stock par value (in dollars per share)	$ 0.00125	$ 0.00125
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Consolidated Statements of Inco

Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Gross written premiums	$ 1,257,000	$ 1,470,735	$ 1,166,773
Ceded written premiums	(609,226)	(574,585)	(404,101)
Net written premiums	647,774	896,150	762,672
Change in net unearned premiums	(40,968)	(72,404)	52,726
Net earned premiums	606,806	823,746	815,398
Net investment income	73,368	75,652	61,256
Net realized and unrealized losses on investments	(16,030)	(2,919)	(5,479)
Other income	4,545	10,646	14,424
Total revenues	668,689	907,125	885,599
Expenses:
Losses and loss adjustment expenses	478,545	672,102	600,276
Other operating expenses	165,498	170,908	201,035
Other expenses	2,138	1,055	1,300
Interest expense	10,033	10,596	11,553
Amortization of intangible assets	538	597	597
Total expenses	656,752	855,258	814,761
Income before income taxes	11,937	51,867	70,838
Income tax expense (benefit):
Current	11,534	18,453	12,867
Deferred	(4,421)	(4,925)	(5,859)
Total income tax expense	7,113	13,528	7,008
Net income	4,824	38,339	63,830
Other comprehensive income (losses):
Net unrealized gains (losses), net of taxes of $6,874 in 2020, $3,358 in 2019, and $(444) in 2018	50,785	46,942	(22,203)
Total comprehensive income	$ 55,609	$ 85,281	$ 41,627
Per share data:
Basic earnings per share (in dollars per share)	$ 0.16	$ 1.27	$ 2.14
Diluted earnings per share (in dollars per share)	0.16	1.25	2.11
Dividend declared per share (in dollars per share)	$ 1.20	$ 1.20	$ 1.20
Weighted-average common shares outstanding:
Basic (in shares)	30,552,210	30,275,184	29,887,990
Diluted (in shares)	30,884,416	30,673,924	30,307,101

Consolidated Statements of In_2

Consolidated Statements of Income and Comprehensive Income (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net unrealized gains (losses), taxes	$ 6,874	$ 3,358	$ (444)

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($)	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Shares	Preferred Shares	Additional Paid-in Capital	Retained Earnings	Retained EarningsCumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss)Cumulative Effect, Period of Adoption, Adjustment
Balances at Dec. 31, 2017	$ 694,699,000		$ 6,000	$ 0	$ 636,149,000	$ 48,198,000		$ 10,346,000
Balances (ASU 2016-01) at Dec. 31, 2017		$ 0					$ 4,682,000		$ (4,682,000)
Balances (ASU 2018-02) at Dec. 31, 2017		0					(711,000)		$ 711,000
Balances (in shares) at Dec. 31, 2017			29,696,682
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63,830,000					63,830,000
Other comprehensive income (loss)	(22,203,000)							(22,203,000)
Dividends	(36,246,000)					(36,246,000)
Exercise of stock options	4,045,000				4,045,000
Exercise of stock options (in shares)			237,319
Vesting of RSUs	(1,112,000)				(1,112,000)
Vesting of RSUs (in shares)			54,459
Compensation expense under share incentive plans	6,228,000				6,228,000
Balances at Dec. 31, 2018	$ 709,241,000	8,280,000	$ 6,000	0	645,310,000	79,753,000	8,280,000	(15,828,000)
Balances (in shares) at Dec. 31, 2018	29,988,460		29,988,460
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 38,339,000					38,339,000
Other comprehensive income (loss)	46,942,000							46,942,000
Dividends	(36,786,000)					(36,786,000)
Exercise of stock options	7,124,000				7,124,000
Exercise of stock options (in shares)			345,434
Vesting of RSUs	(1,737,000)				(1,737,000)
Vesting of RSUs (in shares)			90,497
Compensation expense under share incentive plans	$ 7,178,000				7,178,000
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Balances at Dec. 31, 2019	$ 778,581,000		$ 6,000	0	657,875,000	89,586,000		31,114,000
Balances (ASU 2016-13) at Dec. 31, 2019		(265,000)					(265,000)
Balances (ASU 2019-05) at Dec. 31, 2019		$ (7,827,000)					$ (7,827,000)
Balances (in shares) at Dec. 31, 2019	30,424,391		30,424,391
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 4,824,000					4,824,000
Other comprehensive income (loss)	50,785,000							50,785,000
Dividends	(37,091,000)					(37,091,000)
Exercise of stock options	1,327,000				1,327,000
Exercise of stock options (in shares)			113,346
Vesting of RSUs	(2,351,000)				(2,351,000)
Vesting of RSUs (in shares)			111,524
Compensation expense under share incentive plans	7,625,000				7,625,000
Balances at Dec. 31, 2020	$ 795,608,000		$ 6,000	$ 0	$ 664,476,000	$ 49,227,000		$ 81,899,000
Balances (in shares) at Dec. 31, 2020	30,649,261		30,649,261

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income		$ 4,824,000	$ 38,339,000	$ 63,830,000
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred policy acquisition costs		(76,525,000)	(91,449,000)	(93,188,000)
Amortization of policy acquisition costs		75,578,000	83,893,000	111,103,000
Net realized and unrealized losses on investments		16,030,000	2,919,000	5,479,000
Impairment of intangible assets		0	0	200,000
Distributions from equity method investments		3,162,000	2,834,000	7,499,000
Income from equity method investments		(3,208,000)	(4,598,000)	(3,540,000)
Trading securities purchases, sales, and maturities, net		0	0	3,804,000
Deferred U.S. federal income tax benefit		(4,421,000)	(4,925,000)	(5,859,000)
Provision for depreciation and amortization		5,019,000	4,063,000	4,215,000
Share based compensation expense		7,625,000	7,178,000	6,228,000
Excess tax benefits from equity incentive plan transactions		(679,000)	(1,099,000)	(2,699,000)
Change in operating assets and liabilities:
Reserve for losses and loss adjustment expenses		146,574,000	384,047,000	369,110,000
Unearned premiums		105,994,000	137,904,000	(31,641,000)
Premiums receivable and agents’ balances		(115,000)	(61,563,000)	44,537,000
Reinsurance balances		(213,264,000)	(235,632,000)	(187,024,000)
Funds held		(339,244,000)	1,199,164,000	0
Payable to insurance companies		(396,000)	263,000	(2,029,000)
Other		(784,000)	27,684,000	3,000
Net cash (used in) provided by operating activities	[1]	(273,830,000)	1,489,022,000	290,028,000
Securities available-for-sale:
Purchases – fixed maturity securities		(573,482,000)	(450,793,000)	(418,011,000)
Sales – fixed maturity securities		37,674,000	121,245,000	95,793,000
Maturities and calls – fixed maturity securities		240,322,000	128,809,000	129,139,000
Purchases – equity securities		(16,713,000)	(4,975,000)	(7,507,000)
Sales – equity securities		6,838,000	8,656,000	5,578,000
Bank loan participations:
Purchases		(77,965,000)	(102,794,000)	(203,328,000)
Sales		135,664,000	48,415,000	123,114,000
Maturities		32,653,000	45,277,000	58,742,000
Other invested assets:
Purchases		(1,937,000)	0	(6,993,000)
Return of capital		353,000	1,877,000	921,000
Redemptions		16,292,000	10,998,000	0
Securities receivable or payable, net		(1,777,000)	5,404,000	2,268,000
Short-term investments, net		26,636,000	(74,959,000)	(45,162,000)
Other		(549,000)	(519,000)	(1,326,000)
Net cash used in investing activities		(175,991,000)	(263,359,000)	(266,772,000)
Financing activities
Senior debt issuances		164,000,000	60,000,000	20,000,000
Senior debt repayments		(60,000,000)	(20,000,000)	0
Dividends paid		(37,051,000)	(36,720,000)	(36,123,000)
Issuances of common shares under equity incentive plans		2,580,000	8,286,000	5,172,000
Common share repurchases		(3,604,000)	(2,899,000)	(2,239,000)
Other financing activities		0	(711,000)	(1,104,000)
Net cash provided by (used in) financing activities		65,925,000	7,956,000	(14,294,000)
Change in cash, cash equivalents, and restricted cash equivalents		(383,896,000)	1,233,619,000	8,962,000
Cash, cash equivalents, and restricted cash equivalents at beginning of year		1,406,076,000	172,457,000	163,495,000
Cash, cash equivalents, and restricted cash equivalents at end of year		1,022,180,000	1,406,076,000	172,457,000
Supplemental information
U.S. federal income taxes paid, net		17,236,000	18,719,000	8,174,000
Interest paid		11,305,000	12,354,000	11,269,000
Cash and cash equivalents		162,260,000	206,912,000
Restricted cash equivalents		859,920,000	1,199,164,000	0
Change in restricted cash equivalents		339,244,000	$ (1,199,164,000)	$ 0
Cash provided by operating activities, excluding the reduction in collateral funds		$ 65,400,000
[1]	Cash used in operating activities for the year ended December 31, 2020 primarily reflects $339.2 million of restricted cash equivalents returned to a former insured, per the terms of a collateral trust (see Amounts Recoverable from an Indemnifying Party in the Liquidity and Capital Resources discussion of Management's Discussion and Analysis of Financial Condition and Results of Operations). Excluding the reduction in the collateral funds, cash provided by operating activities was $65.4 million for the year ended December 31, 2020.

Accounting Policies

Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Accounting Policies	Accounting Policies Organization James River Group Holdings, Ltd. (referred to as “JRG Holdings” or, with its subsidiaries, the “Company”) is an exempted holding company registered in Bermuda, organized for the purpose of acquiring and managing insurance and reinsurance entities. The Company owns five insurance companies based in the United States (“U.S.”) focused on specialty insurance niches and two Bermuda-based reinsurance companies as described below: • James River Group Holdings UK Limited (“James River UK”) is an insurance holding company formed in 2015 in the United Kingdom (“U.K.”). The Company contributed James River Group, Inc. (“James River Group”), a U.S. insurance holding company, to James River UK in 2015. • James River Group is a Delaware domiciled insurance holding company formed in 2002, which owns all of the Company’s U.S.-based subsidiaries, either directly or indirectly through one of its wholly-owned U.S. subsidiaries. James River Group oversees the Company’s U.S. insurance operations and maintains all of the outstanding debt in the U.S. • James River Insurance Company (“James River Insurance”) is an Ohio domiciled excess and surplus lines insurance company that, with its wholly-owned insurance subsidiary, James River Casualty Company, is authorized to write business in every state and the District of Columbia. • Falls Lake National Insurance Company (“Falls Lake National”) is an Ohio domiciled insurance company which wholly owns Stonewood Insurance Company (“Stonewood Insurance”), a North Carolina domiciled company, and Falls Lake Fire and Casualty Company, a California domiciled company. Falls Lake National primarily write specialty admitted fronting and program business and individual risk workers' compensation insurance. • JRG Reinsurance Company Ltd. (“JRG Re”) was formed in 2007 and commenced operations in 2008. JRG Re, a Bermuda domiciled reinsurer, primarily provides non-catastrophe casualty reinsurance to U.S. third parties and, through December 31, 2017, to the Company’s U.S.-based insurance subsidiaries. • Carolina Re Ltd ("Carolina Re") was formed in 2018 and as of January 1, 2018 provides reinsurance to the Company's U.S.-based insurance subsidiaries. Carolina Re is also the cedent on a stop loss reinsurance treaty with JRG Re. Basis of Presentation and Principles of Consolidation The consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”), which vary in some respects from statutory accounting practices (“SAP”) which are prescribed or permitted by the various state insurance departments in the U.S. or by insurance regulators in Bermuda. The accompanying consolidated financial statements include the accounts and operations of the Company and its subsidiaries. Intercompany transactions and balances have been eliminated. Estimates and Assumptions Preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying disclosures. Those estimates are inherently subject to change, and actual results may ultimately differ from those estimates. Fixed Maturity and Equity Securities Fixed maturity securities classified as “available-for-sale” are carried at fair value, and unrealized gains and losses on such securities, net of any deferred taxes, are reported as a separate component of accumulated other comprehensive income. The Company does not have any securities classified as “held-to-maturity” or “trading”. Fair value generally represents quoted market value prices for securities traded in the public marketplace or prices analytically determined using bid or closing prices for securities not traded in the public marketplace. Premiums and discounts on mortgage-backed securities and asset-backed securities are amortized or accrued using the constant yield method which considers anticipated prepayments at the date of purchase. To the extent that the estimated lives of such securities change as a result of changes in estimated prepayment rates, the adjustments are included in net investment income using the retrospective method. Realized investment gains or losses are determined on a specific identification basis. Interest income is recognized as earned, and dividend income is recognized on the ex-dividend date. The Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments on January 1, 2020. This update changed the impairment model for available-for-sale fixed maturities and requires the Company to determine whether unrealized losses on available-for-sale fixed maturities are due to credit-related factors. An allowance for credit losses is established for any credit-related impairments, limited to the amount by which fair value is below amortized cost. Changes in the allowance for credit losses are recognized in earnings and included in n et realized and unrealized gains (losses) on investments . Unrealized losses that are not credit-related will continue to be recognized in other comprehensive income. The Company considers the extent to which fair value is below amortized cost in determining whether a credit-related loss exists. The Company also considers the credit quality rating of the security, with a special emphasis on securities downgraded below investment grade. A comparison is made between the present value of expected future cash flows for a security and its amortized cost. If the present value of future expected cash flows is less than amortized cost, a credit loss is presumed to exist and an allowance for credit losses is established. Management may conclude that a qualitative analysis is sufficient to support its conclusion that the present value of the expected cash flows equals or exceeds a security’s amortized cost. Effective January 1, 2018, with the adoption of ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities , equity securities (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) are measured at fair value with changes in fair value recognized in net realized and unrealized gains or losses. Prior to the adoption of ASU 2016-01, changes in the fair value of equity securities were recognized net of taxes as a component of accumulated other comprehensive income. Bank Loan Participations Bank loan participations are managed by a specialized outside investment manager. In connection with the adoption of ASU 2016-13, the Company elected the fair value option in accounting for bank loan participations effective January 1, 2020. Under the fair value option, bank loan participations are measured at fair value, and changes in unrealized gains and losses in bank loan participations are reported in our income statement as net realized and unrealized gains (losses) on investments. Losses due to credit-related impairments on bank loan participations are determined based upon consultations and advice from the Company's specialized investment manager and consideration of any adverse situations that could affect the borrower's ability to repay, the estimated value of underlying collateral, and other relevant factors. Interest income is accrued on the unpaid principal balance. Discounts and premiums are amortized to income using the interest method. Prior to the election of the fair value option on January 1, 2020, bank loan participations were generally stated at their outstanding unpaid principal balances net of unamortized premiums or discounts and net of any allowance for credit losses. The allowance for credit losses was maintained at a level considered adequate to absorb estimated probable credit losses. Generally, the accrual of interest on a bank loan participation is discontinued when the contractual payment of principal or interest has become 90 days past due or management has serious doubts about further collectability of principal or interest. A bank loan participation may remain on accrual status if it is in the process of collection and is either guaranteed or well secured. Interest received on nonaccrual loans generally is reported as investment income. There were no bank loans on nonaccrual status at December 31, 2020 or 2019. Generally, bank loan participations are restored to accrual status when the obligation is brought current, has performed in accordance with the contractual terms for a reasonable period of time, and the ultimate collectability of the total contractual principal and interest is no longer in doubt. Other Invested Assets Other invested assets at December 31, 2020 and 2019 include the Company’s interests in private debt and equity investments. The investments are primarily focused in renewable energy, limited partnerships, and bank holding companies. Equity interests in various limited liability companies (“LLCs”) and limited partnerships are accounted for under the equity method, as the Company has determined that the equity method best reflects its economic interest in the underlying equity investment. Short-Term Investments Short-term investments are carried at amortized cost, which approximates fair value. Short-term investments have maturities greater than three months but less than one year at the date of purchase. Cash Equivalents The Company considers highly liquid investments with maturities of three months or less at the date of purchase to be cash equivalents. Restricted Cash Equivalents The Company considers highly liquid investments with maturities of three months or less at the date of purchase that are segregated for a specific use to be restricted cash equivalents. Certain restricted cash equivalents invested in funds with floating net asset values are measured at fair value with changes in fair value recognized in net income. Direct Written Premiums Direct written premiums are earned on a pro rata basis over the terms of the policies, generally 12 months. The portion of premiums written applicable to the unexpired terms of the policies in force is recorded as unearned premiums. Policies are accounted for on an individual basis, with no aggregation by counterparty. Assumed Reinsurance Premiums Assumed reinsurance written premiums include amounts reported by brokers and ceding companies, supplemented by the Company’s own estimates of premiums when reports have not been received. Premiums on the Company’s excess of loss and pro rata reinsurance contracts are estimated when the business is underwritten. For excess of loss contracts, the deposit premium, as defined in the contract, is generally recorded as an estimate of premiums written at the inception date of the treaty. Estimates of premiums written under pro rata contracts are recorded in the period in which the underlying risks are expected to begin and are based on information provided by the brokers and the ceding companies. Reinsurance premium estimates are reviewed by management periodically. Any adjustment to these estimates is recorded in the period in which it becomes known. Reinsurance premiums assumed are earned over the terms of the underlying policies or reinsurance contracts. Contracts and policies written on a “losses occurring” basis cover claims that may occur during the term of the contract or policy, which is typically 12 months. Accordingly, the premium is earned evenly over the term. Contracts which are written on a “risks attaching” basis cover claims which attach to the underlying insurance policies written during the terms of such contracts. Premiums earned on such contracts usually extend beyond the original term of the reinsurance contract, typically resulting in recognition of premiums earned over a 24-month period in proportion to the level of underlying exposure. Contracts are accounted for on an individual basis, with no aggregation by counterparty. Premiums Receivable and Agents’ Balances, Net Premiums receivable and agents’ balances are carried at face value net of any allowance for credit losses. The allowance for credit losses represents the current estimate of expected credit losses based on the Company’s assessment of the collectability of receivables that are past due, historical collection percentages, and consideration of current economic conditions and expectations of future conditions that could affect ultimate collections. Receivables greater than 90 days past due were $6.9 million and $3.3 million at December 31, 2020 and 2019, respectively. The allowance for credit losses was $8.3 million and $5.7 million at December 31, 2020 and 2019, respectively. Bad debt expense was $3.3 million for the year ended December 31, 2020, $2.5 million for the year ended December 31, 2019, and $1.5 million for the year ended December 31, 2018. Receivables written off against the allowance for credit losses totaled $660,000 for the year ended December 31, 2020, $812,000 for the year ended December 31, 2019, and $313,000 for the year ended December 31, 2018. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. Deferred Policy Acquisition Costs Costs which are incrementally or directly related to the successful acquisition of new or renewal insurance business are deferred. These deferred costs are primarily commissions to agents, ceding commissions paid on reinsurance assumed, premium taxes, and the portion of underwriting fixed compensation and payroll related fringe benefits directly related to an insurance contract that has been acquired, net of ceding commissions related to reinsurance ceded. Amortization of such policy acquisition costs is charged to expense in proportion to premium earned over the estimated policy life. To the extent that unearned premiums on existing policies are not adequate to cover projected related costs and expenses, deferred policy acquisition costs are charged to earnings. The Company considers anticipated investment income in determining whether a premium deficiency exists. Reinsurance and Adjustable Features of Insurance and Reinsurance Contracts Certain premiums and losses are ceded to other insurance companies or assumed from other insurance companies under various excess of loss and quota-share reinsurance contracts. The Company enters into ceded reinsurance contracts to limit its exposure to large losses, to limit exposure on new lines of insurance written by the Company, and to provide additional capacity for growth. Premiums, commissions, and losses and loss adjustment expenses on reinsured business are accounted for on a basis consistent with that used in accounting for the original policies issued and the terms of the reinsurance contracts. Reinsurance recoverables and prepaid reinsurance premiums are reported as assets. The Company uses a provision matrix to calculate the allowance for credit losses on reinsurance recoverables by applying impairment rates based on historical loss data to similarly rated reinsurance companies based on the expected duration of the receivables. The Company also considers the expected impact of current and future expected economic conditions and adjusts estimates if needed based on an evaluation of these factors. The allowance for credit losses on reinsurance recoverables at December 31, 2020 was $335,000. Other amounts payable to insurance companies and reinsurers or receivable from insurance companies and reinsurers are netted where the right of offset exists. The Company receives ceding commissions in connection with certain ceded reinsurance. The ceding commissions are recorded as a reduction of other operating expenses. Certain reinsurance contracts include provisions that adjust premiums or acquisition expenses based upon the loss experience under the contracts. Premiums written and earned, as well as related acquisition expenses are recorded based upon the projected loss experience under the contracts. The Company’s Specialty Admitted Insurance segment writes insurance under specialty admitted fronting and program arrangements. The fronting and program arrangements may contain contractual provisions that adjust acquisition expenses based upon loss experience under the contracts. The specialty admitted fronting and program arrangements are significantly reinsured. These reinsurance contracts may also contain provisions that adjust premiums or acquisition expenses based upon the loss experience under the contracts. Premiums written and earned, as well as related acquisition expenses, are recorded based upon the projected loss experience under the contracts. Other Income Other income is principally comprised of fee income earned on policies for which the Company has no exposure to underwriting risk. Fee income of $3.4 million, $9.5 million, and $13.9 million is included in other income for the years ended December 31, 2020, 2019, and 2018, respectively. Fees are earned on a pro rata basis over the service period of the underlying business. Policies are accounted for on an individual basis, with no aggregation by counterparty. Income Taxes Deferred tax assets and deferred tax liabilities are provided for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of assets and liabilities and their respective U.S. tax basis. Deferred tax assets and liabilities are measured using enacted U.S. corporate tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax assets are reduced by a valuation allowance only when management believes it is more likely than not that some, or all, of the deferred tax assets will not be realized. Effective January 1, 2018, the Company adopted ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This update was issued as a result of the enactment of Public Law No. 115-97, informally titled the Tax Cuts and Jobs Act (the "Tax Act"), on December 22, 2017. The ASU allows for the option to reclassify the stranded tax effects resulting from the implementation of the Tax Act out of accumulated other comprehensive income and into retained earnings. The reclassification resulted in a $711,000 decrease to the Company's retained earnings with a corresponding increase to accumulated other comprehensive income in the first quarter of 2018. Goodwill Goodwill is tested annually for impairment in the fourth quarter of each calendar year, or more frequently if events or changes in circumstances indicate that the carrying amount of the Company’s reporting units, including goodwill, may exceed their fair values. The Company first assesses qualitative factors in determining whether it is necessary to perform the quantitative goodwill impairment test. If management determines that it is more likely than not that the fair value of a reporting unit is less than the carrying value based on qualitative factors then they will perform the quantitative goodwill impairment test. For the quantitative goodwill impairment testing, the fair value of the reporting units is determined using a combination of a market approach and an income approach which projects the future cash flows produced by the reporting units and discounts those cash flows to their present value. The projection of future cash flows is necessarily dependent upon assumptions on the future levels of income as well as business trends, prospects, market, and economic conditions. The results of the two approaches are weighted to determine the fair value of each reporting unit. When the fair value is less than the carrying value of the net assets of the reporting unit, including goodwill, an impairment loss is charged to operations. To determine the amount of any goodwill impairment, the implied fair value of reporting unit goodwill is compared to the carrying amount of that goodwill. The implied fair value of goodwill is determined in the same manner as the amount of goodwill recognized in a business combination is determined. That is, the fair value of a reporting unit is assigned to all of the assets and liabilities of that unit (including any unrecognized intangible assets) as if the reporting unit had been acquired in a business combination. The excess of the fair value of a reporting unit over the amounts assigned to its assets and liabilities is the implied fair value of goodwill. Intangible Assets, Net Intangible assets are initially recognized and measured at fair value. Specifically identified intangible assets with indefinite lives include trademarks and state insurance licenses and authorities. Other specifically identified intangible assets with lives ranging from 7.0 to 27.5 years represent relationships with brokers. These intangible assets are amortized on a straight-line basis over their estimated useful lives. Intangible assets with indefinite useful lives are reviewed for impairment at least annually. In evaluating whether there has been impairment to the intangible asset, management determines the fair value of the intangible asset and compares the resulting fair value to the carrying value of the intangible asset. If the carrying value exceeds the fair value, the intangible asset is written down to fair value, and the impairment is reported through earnings. The Company evaluates intangible assets with definite lives for impairment when impairment indicators are noted. Impairment of Long-Lived Assets Long-lived assets with finite lives are tested for impairment whenever recognized events or changes in circumstances indicate the carrying value of these assets may not be recoverable. If indicators of impairment are present, fair value is calculated using estimated future cash flows expected to be generated from the use of those assets. An impairment loss is recognized only if the carrying amount of a long-lived asset or asset group is not recoverable and exceeds its fair value. The carrying amount of a long-lived asset or asset group is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset or asset group. That assessment is based on the carrying amount of the asset or asset group at the date it is tested for recoverability. An impairment loss is measured as the amount by which the carrying amount of a long-lived asset or asset group exceeds its fair value. Property and Equipment, Net Property and equipment, which is included in “other assets” in the accompanying consolidated balance sheets, is reported at cost less accumulated depreciation and is depreciated principally on a straight-line basis over the estimated useful lives of the depreciable assets, generally three Reserve for Losses and Loss Adjustment Expenses The reserve for losses and loss adjustment expenses represents the estimated ultimate cost of all reported and unreported losses and loss adjustment expenses incurred and unpaid at the balance sheet date. The Company does not discount this reserve. The process of estimating the reserve for losses and loss adjustment expenses requires a high degree of judgment and is subject to a number of variables. The reserve for losses and loss adjustment expenses is estimated using individual case-basis valuations and statistical analyses. Those estimates are subject to the effects of trends in loss severity and frequency. The Company utilizes various actuarially-accepted reserving methodologies in determining the continuum of expected outcomes for its reserves. These methodologies utilize various inputs, including management’s initial expected loss ratio (the ratio of losses and loss adjustment expenses incurred to net earned premiums), expected reporting patterns and payment patterns for losses and loss adjustment expenses (based on insurance industry data and the Company’s own experience), and the Company’s actual paid and reported losses and loss adjustment expenses. An internal actuary reviews these results and (after applying appropriate professional judgment and other actuarial techniques that are considered necessary) presents recommendations to the Company’s management. Management uses this information and its judgment to make decisions on the final recorded reserve for losses and loss adjustment expenses. Management believes that the use of judgment is necessary to arrive at a best estimate for the reserve for losses and loss adjustment expenses given the long-tailed nature of the business generally written by the Company and the limited operating experience of the Casualty Reinsurance segment, the fronting and program business in the Specialty Admitted Insurance segment, and the commercial auto business in the Excess and Surplus Lines segment. Catastrophes of significant magnitude, including hurricanes and earthquakes, involve complex coverage issues. In estimating the reserve for losses and loss adjustment expenses for these catastrophes, management uses case reserve estimates based on information obtained from site inspections by the Company’s adjustors and the terms of coverage provided in the policies. Management estimates reserves for incurred but not reported claims for these catastrophes using judgment based on an assessment of the Company’s property insurance exposures where the catastrophes occur and the Company’s progress in settling claims. Although management believes that the reserve for losses and loss adjustment expenses is reasonable, it is possible that the Company’s actual incurred losses and loss adjustment expenses will not develop in a manner consistent with the assumptions inherent in the determination of these reserves. Specifically, the Company’s actual ultimate loss ratio could differ from management’s initial expected loss ratio and/or the Company’s actual reporting patterns for losses could differ from the expected reporting patterns. Accordingly, the ultimate settlement of losses and the related loss adjustment expenses may vary significantly from the estimates included in the Company’s consolidated financial statements. These estimates are reviewed continually by management and are adjusted as necessary as experience develops or new information becomes known; such adjustments are included in current operations. Share Based Compensation The Company expenses the fair value of share equity awards over the vesting period of the award on a straight-line basis. The Black-Scholes-Merton option pricing model is used to value the options granted (see Note 12). Forfeitures of share-based awards are recognized as they occur. As the share based compensation expense is incurred, a corresponding increase to additional paid-in capital in shareholders’ equity is recognized. Share based compensation expense is reflected in “other operating expenses” in the accompanying consolidated statements of income and comprehensive income. Variable Interest Entities Entities that do not have sufficient equity at risk to allow the entity to finance its activities without additional financial support or in which the equity investors, as a group, do not have the characteristic of a controlling financial interest are referred to as variable interest entities (“VIE”). A VIE is consolidated by the variable interest holder that is determined to have the controlling financial interest (primary beneficiary) as a result of having both the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE’s capital structure, contractual terms, nature of the VIE’s operations and purpose, and the Company’s relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE. The Company reassesses its VIE determination with respect to an entity on an ongoing basis. The Company holds interests in VIEs through certain equity method investments included in “other invested assets” in the accompanying consolidated balance sheets. The Company has determined that it should not consolidate any of the VIEs as it is not the primary beneficiary in any of the relationships. Although the investments resulted in the Company holding variable interests in the entities, they did not empower the Company to direct the activities that most significantly impact the economic performance of the entities. The Company’s investments related to these VIEs totaled $30.1 million and $31.2 million as of December 31, 2020 and 2019, respectively, representing the Company’s maximum exposure to loss. Earnings Per Share Basic earnings per share excludes dilution and is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted earnings per share reflects the dilution that could occur if securities or other contracts to issue common shares or common share equivalents were exercised or converted into common shares as calculated using the treasury stock method. When inclusion of common share equivalents increases the earnings per share or reduces the loss per share, the effect on earnings is anti-dilutive, and the diluted net earnings or net loss per share is computed excluding these common share equivalents. The following represents a reconciliation of the numerator and denominator of the basic and diluted earnings per share computations contained in the consolidated financial statements. Net Income Weighted-Average Earnings (in thousands, except per share data) Year ended December 31, 2020 Basic $ 4,824 30,552,210 $ 0.16 Common share equivalents — 332,206 — Diluted $ 4,824 30,884,416 $ 0.16 Year ended December 31, 2019 Basic $ 38,339 30,275,184 $ 1.27 Common share equivalents — 398,740 (0.02) Diluted $ 38,339 30,673,924 $ 1.25 Year ended December 31, 2018 Basic $ 63,830 29,887,990 $ 2.14 Common share equivalents — 419,111 (0.03) Diluted $ 63,830 30,307,101 $ 2.11 Common share equivalents relate to our outstanding equity awards (stock options and RSUs). For the year ended December 31, 2020, all common share equivalents are dilutive. For the years ended December 31, 2019 and 2018, common share equivalents of 9,735 shares and 180,329 shares, respectively, are excluded from the calculations of diluted earnings per share as their effects are anti-dilutive. Adopted Accounting Standards On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , using the modified retrospective approach, by which a cumulative-effect adjustment was made to retained earnings as of the date of adoption. This update requires financial assets measured at amortized cost, such as bank loan participations held for investment, to be presented at the net amount expected to be collected by means of an allowance for credit losses that is reflected in net income. Credit losses relating to available-for-sale debt securities are recorded through an allowance for credit losses, with the amount of the allowance limited to the amount by which fair value is below amortized cost. In connection with the adoption of this ASU, the Company elected the fair value option in accounting for bank loan participations effective January 1, 2020. The targeted transition relief offered by ASU 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief was applied to elect the fair value option to account for bank loan participations already held at the January 1, 2020 date of adoption. Under the fair value option, bank loan participations are measured at fair value, and changes in unrealized gains and losses in bank loan participations are reported in our income statement as net realized and unrealized gains (losses) on investments. At adoption on January 1, 2020, the Company reduced the carrying value of its bank loan portfolio to fair value through an $8.4 million adjustment with a $7.8 million (net of tax) cumulative effect adjustment to reduce retained earnings. Upon adoption of this ASU, the Company established an allowance for credit losses on reinsurance balances through a $265,000 (net of tax) cumulative effect adjustment to re

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investments	Investments The Company’s available-for-sale fixed maturity securities are summarized as follows: Cost or Gross Gross Fair (in thousands) December 31, 2020 Fixed maturity securities: State and municipal $ 277,241 $ 19,203 $ (39) $ 296,405 Residential mortgage-backed 286,104 7,784 (40) 293,848 Corporate 715,145 52,098 (421) 766,822 Commercial mortgage and asset-backed 314,911 12,611 (803) 326,719 U.S. Treasury securities and obligations guaranteed by the U.S. government 97,489 2,360 (1) 99,848 Total fixed maturity securities, available-for-sale $ 1,690,890 $ 94,056 $ (1,304) $ 1,783,642 December 31, 2019 Fixed maturity securities: State and municipal $ 159,894 $ 7,949 $ (742) $ 167,101 Residential mortgage-backed 261,524 3,244 (622) 264,146 Corporate 611,304 21,306 (389) 632,221 Commercial mortgage and asset-backed 249,309 3,954 (806) 252,457 U.S. Treasury securities and obligations guaranteed by the U.S. government 114,477 1,229 (39) 115,667 Redeemable preferred stock 2,025 9 — 2,034 Total fixed maturity securities, available-for-sale $ 1,398,533 $ 37,691 $ (2,598) $ 1,433,626 The amortized cost and fair value of available-for-sale investments in fixed maturity securities at December 31, 2020 are summarized, by contractual maturity, as follows: Cost or Fair (in thousands) One year or less $ 115,048 $ 116,404 After one year through five years 457,434 485,506 After five years through ten years 283,761 306,655 After ten years 233,632 254,510 Residential mortgage-backed 286,104 293,848 Commercial mortgage and asset-backed 314,911 326,719 Total $ 1,690,890 $ 1,783,642 Actual maturities may differ for some securities because borrowers have the right to call or prepay obligations with or without penalties. The following table shows the Company’s gross unrealized losses and fair value for available-for-sale securities aggregated by investment category and the length of time that individual securities have been in a continuous unrealized loss position: Less Than 12 Months 12 Months or More Total Fair Gross Fair Gross Fair Gross (in thousands) December 31, 2020 Fixed maturity securities: State and municipal $ 7,193 $ (39) $ — $ — $ 7,193 $ (39) Residential mortgage-backed 3,649 (40) — — 3,649 (40) Corporate 28,607 (421) — — 28,607 (421) Commercial mortgage and asset-backed 18,427 (447) 38,802 (356) 57,229 (803) U.S. Treasury securities and obligations guaranteed by the U.S. government 2,291 (1) — — 2,291 (1) Total fixed maturity securities, available-for-sale $ 60,167 $ (948) $ 38,802 $ (356) $ 98,969 $ (1,304) December 31, 2019 Fixed maturity securities: State and municipal $ 30,028 $ (741) $ 667 $ (1) $ 30,695 $ (742) Residential mortgage-backed 23,632 (78) 37,363 (544) 60,995 (622) Corporate 45,550 (365) 9,933 (24) 55,483 (389) Commercial mortgage and asset-backed 46,434 (406) 56,720 (400) 103,154 (806) U.S. Treasury securities and obligations guaranteed by the U.S. government 8,474 (22) 7,168 (17) 15,642 (39) Total fixed maturity securities, available-for-sale $ 154,118 $ (1,612) $ 111,851 $ (986) $ 265,969 $ (2,598) The Company held securities of 67 issuers that were in an unrealized loss position at December 31, 2020 with a total fair value of $99.0 million and gross unrealized losses of $1.3 million. None of the fixed maturity securities with unrealized losses has ever missed, or been delinquent on, a scheduled principal or interest payment. At December 31, 2020, 99.6% of the Company’s fixed maturity security portfolio was rated “BBB-” or better (“investment grade”) by Standard & Poor’s or received an equivalent rating from another nationally recognized rating agency. The Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments on January 1, 2020. This update changed the impairment model for available-for-sale fixed maturities and requires the Company to determine whether unrealized losses on available-for-sale fixed maturities are due to credit-related factors. An allowance for credit losses is established for any credit-related impairments, limited to the amount by which fair value is below amortized cost. Changes in the allowance for credit losses are recognized in earnings and included in net realized and unrealized gains (losses) on investments. Unrealized losses that are not credit-related will continue to be recognized in other comprehensive income. The Company considers the extent to which fair value is below amortized cost in determining whether a credit-related loss exists. The Company also considers the credit quality rating of the security, with a special emphasis on securities downgraded below investment grade. A comparison is made between the present value of expected future cash flows for a security and its amortized cost. If the present value of future expected cash flows is less than amortized cost, a credit loss is presumed to exist and an allowance for credit losses is established. Management may conclude that a qualitative analysis is sufficient to support its conclusion that the present value of expected cash flows equals or exceeds a security's amortized cost. As a result of this review, management concluded that there were no credit-related impairments of fixed maturities at December 31, 2020. Management does not intend to sell the securities in an unrealized loss position, and it is not "more likely than not" that the Company will be required to sell these securities before a recovery in their value to their amortized cost basis occurs. Management concluded that none of the fixed maturity securities with an unrealized loss at December 31, 2019 and 2018 experienced an other-than-temporary impairment. In connection with the adoption of ASU 2016-13, the Company elected the fair value option in accounting for bank loan participations effective January 1, 2020. The targeted transition relief offered by ASU 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief was applied to elect the fair value option to account for bank loan participations already held at the January 1, 2020 date of adoption. Under the fair value option, bank loan participations are measured at fair value, and changes in unrealized gains and losses in bank loan participations are reported in our income statement as net realized and unrealized gains (losses) on investments. At adoption on January 1, 2020, the Company applied the amendments on a modified retrospective basis, reducing the carrying value of its bank loan portfolio to fair value through an $8.4 million adjustment with a $7.8 million (net of tax) cumulative effect adjustment to reduce retained earnings. Applying the fair value option to the bank loan portfolio increases volatility in the Company's financial statements, but management believes it is less subjective and less burdensome to implement and maintain than ASU 2016-13, which would have otherwise been required. At December 31, 2020, the Company's bank loan portfolio had an aggregate unpaid principal balance of $159.6 million and an aggregate fair value of $147.6 million. Investment income on bank loan participations included in net investment income was $12.2 million during the year ended December 31, 2020. Net realized and unrealized gains (losses) on investments includes gains of $1.3 million related to changes in unrealized gains and losses on bank loan participations for the year ended December 31, 2020. Management concluded that $8.3 million of unrealized losses were due to credit-related impairments for the year ended December 31, 2020. Losses due to credit-related impairments were determined based upon consultations and advice from the Company's specialized investment manager and consideration of any adverse situations that could affect the borrower's ability to repay, the estimated value of underlying collateral, and other relevant factors. Prior to the election of the fair value option on January 1, 2020, bank loan participations were classified as held-for-investment and carried at amortized cost net of any allowance for credit losses. Under the prior accounting method, management concluded that seven loans from six issuers in the Company's bank loan portfolio were impaired at December 31, 2019. At December 31, 2019, the impaired loans had a carrying value of $6.9 million, unpaid principal of $14.3 million, and an allowance for credit losses of $7.2 million , $5.1 million of which related to two loans from one issuer that was experiencing liquidity concerns resulting from revenue declines and poor growth prospects in its most profitable segment. Management concluded that none of the loans in the Company's bank loan portfolio were impaired at December 31, 2018. Bank loan participations generally have a credit rating that is below investment grade (i.e. below “BBB-” for Standard & Poor’s) at the date of purchase. These bank loans are primarily senior, secured floating-rate debt rated “BB”, “B”, or “CCC” by Standard & Poor’s or an equivalent rating from another nationally recognized rating agency. These bank loans include assignments of, and participations in, performing and non-performing senior corporate debt generally acquired through primary bank syndications and in secondary markets. Bank loans consist of, but are not limited to, term loans, the funded and unfunded portions of revolving credit loans, and other similar loans and investments. Management believed that it was probable at the time that these loans were acquired that the Company would be able to collect all contractually required payments receivable. Interest income on bank loan participations is accrued on the unpaid principal balance, and discounts and premiums on bank loan participations are amortized to income using the interest method. Generally, the accrual interest on a bank loan participation is discontinued when the contractual payment of principal or interest has become 90 days past due or management has serious doubts about further collectability of principal or interest. A bank loan participation may remain on accrual status if it is in the process of collection and is either guaranteed or well secured. Generally, bank loan participations are restored to accrual status when the obligation is brought current, has performed in accordance with the contractual terms for a reasonable period of time, and the ultimate collectability of the total contractual principal and interest is no longer in doubt. Interest received on nonaccrual loans generally is reported as investment income. There were no bank loans on nonaccrual status at December 31, 2020 or 2019. The average recorded investment in impaired bank loans was $3.5 million and $2.6 million during the years ended December 31, 2019 and 2018, respectively, and investment income of $293,000 and $125,000, was recognized during the time that the loans were impaired. The Company recorded losses of $8.9 million and $858,000 during the years ended December 31, 2019 and 2018, respectively, for changes in the fair value of impaired bank loans. At December 31, 2019, unamortized discounts on bank loan participations were $2.4 million, and unamortized premiums were $4,000. Major categories of the Company’s net investment income are summarized as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Fixed maturity securities $ 45,070 $ 39,875 $ 34,129 Bank loan participations 12,150 19,772 18,279 Equity securities 4,800 5,262 5,240 Other invested assets 9,181 6,254 5,165 Cash, cash equivalents, restricted cash equivalents, and short-term investments 6,619 9,210 2,677 Gross investment income 77,820 80,373 65,490 Investment expense (4,452) (4,721) (4,234) Net investment income $ 73,368 $ 75,652 $ 61,256 The Company’s net realized and unrealized losses and gains on investments are summarized as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Fixed maturity securities: Gross realized gains $ 1,098 $ 1,575 $ 422 Gross realized losses (53) (494) (976) 1,045 1,081 (554) Equity securities: Gross realized gains — 11 — Gross realized losses (1,441) (232) (62) Changes in fair values of equity securities (215) 6,257 (5,970) (1,656) 6,036 (6,032) Bank loan participations: Gross realized gains 554 846 2,279 Gross realized losses (17,286) (10,902) (1,166) Changes in fair values of bank loan participations 1,318 — — (15,414) (10,056) 1,113 Short-term investments and other: Gross realized gains 77 21 — Gross realized losses (2) (1) (6) Changes in fair values of short-term investments and other (80) — — (5) 20 (6) Total $ (16,030) $ (2,919) $ (5,479) The following table summarizes the change in the Company’s available-for-sale gross unrealized gains or losses by investment type: Year Ended December 31, 2020 2019 2018 (in thousands) Change in gross unrealized gains (losses): Fixed maturity securities $ 57,659 $ 50,300 $ (22,643) Total $ 57,659 $ 50,300 $ (22,643) The Company invests selectively in private debt and equity opportunities. These investments, which together comprise the Company’s other invested assets, are primarily focused in renewable energy, limited partnerships, and bank holding companies. Carrying Value Investment Income December 31, Year Ended December 31, 2020 2019 2020 2019 2018 (in thousands) (in thousands) Renewable energy LLCs (a) $ 30,145 $ 31,219 $ 2,016 $ 2,181 $ 2,974 Renewable energy notes receivable (b) — 8,750 5,630 1,313 1,282 Limited partnerships (c) 11,903 16,741 1,192 2,417 566 Bank holding companies (d) 4,500 4,500 343 343 343 Total other invested assets $ 46,548 $ 61,210 $ 9,181 $ 6,254 $ 5,165 (a) The Company’s Corporate and Other segment owns equity interests ranging from 2.6% to 32.6% in various LLCs whose principal objective is capital appreciation and income generation from owning and operating renewable energy production facilities (wind and solar). The LLCs are managed by an entity for which two of our recent former directors serve as officers, and the Company’s Non-Executive Chairman has invested in certain of these LLCs. The equity method is used to account for the Company’s LLC investments. Income for the LLCs primarily reflects adjustments to the carrying values of investments in renewable energy projects to their determined fair values. The fair value adjustments are included in revenues for the LLCs. Expenses for the LLCs are not significant and are comprised of administrative and interest expenses. The Company received cash distributions from these investments totaling $3.1 million and $757,000 for the years ended December 31, 2020 and 2019, respectively. (b) The Company's Corporate and Other segment has invested in notes receivable for renewable energy projects. At December 31, 2019, the Company held one $8.8 million note issued by an entity for which two of our recent former directors serve as officers . During the current year ended December 31, 2020, the Company received the total principal balance of $8.8 million plus a $5.3 million gain at maturity. Interest on the note was fixed at 15%. Income on the note was $5.6 million, $1.3 million, and $1.3 million for the years ended December 31, 2020, 2019, and 2018, respectively. (c) The Company owns investments in limited partnerships that invest in concentrated portfolios including publicly-traded small cap equities, loans of middle market private equity sponsored companies, equity tranches of collateralized loan obligations ("CLOs"), and tranches of distressed home loans. Income from the partnerships is recognized under the equity method of accounting. The Company’s Corporate and Other segment held investments in limited partnerships with a carrying value of $7.8 million and $3.4 million at December 31, 2020 and 2019, and recognized investment income of $1.3 million, $327,000, and $70,000 for the years ended December 31, 2020, 2019 and 2018, respectively. The Company’s Excess and Surplus Lines segment holds investments in limited partnerships of $4.1 million and $13.3 million at December 31, 2020 and 2019, respectively. Investment losses of $69,000 were recognized on these investments for the year ended December 31, 2020. Investment income of $2.1 million and $496,000 were recognized on these investments for the years ended December 31, 2019 and 2018, respectively. At December 31, 2020, the Company’s Excess and Surplus Lines segment has outstanding commitments to invest another $3.7 million in these limited partnerships and $5.0 million to a newly acquired limited partnership, which will request funding starting in 2021. (d) The Company's Corporate and Other segment holds $4.5 million of subordinated notes issued by a bank holding company for which the Company’s Non-Executive Chairman was previously the Lead Independent Director and an investor and for which one of the Company’s directors was an investor and is currently a lender (the "Bank Holding Company"). Interest on the notes, which mature in 2023, is fixed at 7.6% per annum. Interest income on the notes was $343,000 in each of the years ended December 31, 2020, 2019 and 2018. At December 31, 2020 and 2019, the Company held an investment in a collateralized loan obligation (CLO) where one of the underlying loans was issued by the Bank Holding Company. The investment, with a carrying value of $520,000 and $3.2 million at December 31, 2020 and 2019, is classified as an available-for-sale fixed maturity. The Company maintains fixed maturity securities, short-term investments, accrued investment income, and cash and cash equivalents amounting to $463.4 million at December 31, 2020 in trust accounts or on deposit as collateral for outstanding letters of credit issued as security to third-party reinsureds on reinsurance assumed by JRG Re. At December 31, 2020 and 2019, cash and investments with a fair value of $46.9 million and $36.6 million, respectively, were on deposit with state insurance departments to satisfy regulatory requirements. At December 31, 2020, the Company held no investments in securitizations of alternative-A mortgages or sub-prime mortgages.

Deferred Policy Acquisition Cos

Deferred Policy Acquisition Costs	12 Months Ended
	Dec. 31, 2020
Deferred Policy Acquisition Costs Disclosures [Abstract]
Deferred Policy Acquisition Costs	Deferred Policy Acquisition Costs An analysis of deferred policy acquisition costs is as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Balance at beginning of period $ 62,006 $ 54,450 $ 72,365 Policy acquisition costs deferred: Commissions 51,306 67,303 72,473 Underwriting and other issue expenses 25,219 24,146 20,715 76,525 91,449 93,188 Amortization of policy acquisition costs (75,578) (83,893) (111,103) Net change 947 7,556 (17,915) Balance at end of period $ 62,953 $ 62,006 $ 54,450

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets On December 11, 2007, the Company completed an acquisition of James River Group by acquiring 100% of the outstanding shares of James River Group common stock, referred to herein as the “Merger”. The transaction was accounted for under the purchase method of accounting, and goodwill and intangible assets were recognized by the Company as a result of the transaction. All of the Company’s goodwill is an asset of the Excess and Surplus Lines segment. The Company’s annual testing performed in the fourth quarter of 2020, 2019 and 2018 indicated that no impairment of goodwill had occurred. The carrying amount of goodwill at December 31, 2020 and 2019 was $181.8 million. Accumulated goodwill impairment losses were $99.6 million at December 31, 2020 and 2019. The most recent goodwill impairment losses occurred in 2010. Specifically identifiable intangible assets were acquired in the Merger. During the fourth quarters of 2020, 2019 and 2018, the indefinite-lived intangible assets for trademarks and insurance licenses and authorities were tested for impairment. Intangible assets for broker relationships that have specific lives and are subject to amortization were also reviewed for impairment. In the Specialty Admitted Insurance segment, Falls Lake General Insurance Company was merged into Falls Lake National in the fourth quarter of 2018. In connection with this merger, Falls Lake General Insurance Company surrendered its licenses to the various state insurance departments and reduced the carrying value of its intangible asset for "State Licenses" to $0. This caused a $200,000 impairment in 2018 in the Specialty Admitted Insurance segment. There were no impairments recognized in 2020 or 2019. The gross carrying amounts and accumulated amortization for each major specifically identifiable intangible asset class were as follows: December 31, 2020 2019 Weighted- Gross Accumulated Gross Accumulated (in thousands) Trademarks Indefinite $ 22,200 $ — $ 22,200 $ — Insurance licenses and authorities Indefinite 8,964 — 8,964 — Identifiable intangibles not subject to amortization 31,164 — 31,164 — Broker relationships 24.6 11,611 6,373 11,611 5,835 Identifiable intangible assets subject to amortization 11,611 6,373 11,611 5,835 $ 42,775 $ 6,373 $ 42,775 $ 5,835 Future estimated amortization of specifically identifiable intangible assets as of December 31, 2020 is as follows ( in thousands) : 2021 $ 363 2022 363 2023 363 2024 363 2025 363 Thereafter 3,423 Total $ 5,238 The table below summarizes the changes in the net carrying values of intangible assets by segment for 2020: December 31, 2019 December 31, 2020 Net Carrying Amortization Impairment Net Carrying (in thousands) Excess and Surplus Lines Trademarks $ 19,700 $ — $ — $ 19,700 Insurance licenses and authorities 4,900 — — 4,900 Broker relationships 5,603 (366) — 5,237 30,203 (366) — 29,837 Specialty Admitted Insurance Trademarks 2,500 — — 2,500 Insurance licenses and authorities 4,065 — — 4,065 Broker relationships 172 (172) — — 6,737 (172) — 6,565 Total identifiable intangible assets $ 36,940 $ (538) $ — $ 36,402 The table below summarizes the changes in the net carrying values of intangible assets by segment for 2019: December 31, 2018 December 31, 2019 Net Carrying Amortization Impairment Net Carrying (in thousands) Excess and Surplus Lines Trademarks $ 19,700 $ — $ — $ 19,700 Insurance licenses and authorities 4,900 — — 4,900 Broker relationships 5,965 (362) — 5,603 30,565 (362) — 30,203 Specialty Admitted Insurance Trademarks 2,500 — — 2,500 Insurance licenses and authorities 4,065 — — 4,065 Broker relationships 407 (235) — 172 6,972 (235) — 6,737 Total identifiable intangible assets $ 37,537 $ (597) $ — $ 36,940 Amortization of intangible assets was $362,000 for the Excess and Surplus Lines segment and $235,000 for the Specialty Admitted Insurance segment for the year ended December 31, 2018.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment, net of accumulated depreciation, is included in "other assets" on the consolidated balance sheets and consists of the following: December 31, 2020 2019 (in thousands) Electronic data processing hardware and software $ 3,238 $ 7,007 Furniture and equipment 2,025 2,180 Property and equipment, cost basis 5,263 9,187 Accumulated depreciation (3,975) (7,419) Property and equipment, net $ 1,288 $ 1,768

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Leases The Company has entered into operating leases for office space in Bermuda, North Carolina, Virginia, Arizona, and Georgia. Following the adoption of ASU 2016-02, Leases (Topic 842) , effective January 1, 2019, the present value of future lease payments for the Company’s leases with terms greater than 12 months are included on the consolidated balance sheet as lease liabilities and right-of-use lease assets. Total expected lease payments are based on the lease payments specified in the contract and the stated term, including any options to extend or terminate that the Company is reasonably certain to exercise. The Company has elected the practical expedient to account for lease components and any associated non-lease components as a single lease component, and therefore allocates all of the expected lease payments to the lease component. The lease liability, which represents the Company’s obligation to make lease payments arising from the lease, is calculated based on the present value of expected lease payments over the remaining lease term, discounted using the Company’s collateralized incremental borrowing rate at the commencement date. The lease liability is then adjusted for any prepaid rent, lease incentives received or capitalized initial direct costs to determine the lease asset, which represents the Company's right to use the underlying asset for the lease term. Lease liabilities and right-of-use assets are included in other liabilities other Upon adoption of the new standard on January 1, 2019, the Company derecognized assets of $22.6 million and liabilities of $30.9 million associated with a lease that was designated as build-to-suit under the previous guidance, and recorded a cumulative-effect adjustment to increase retained earnings by $8.3 million. The Company also recorded right-of-use assets of $17.2 million and lease liabilities of $17.8 million at adoption of the new standard associated with the Company's operating leases. At December 31, 2020 and 2019, lease liabilities and right-of-use assets associated with the Company's operating leases were $14.9 million and $14.0 million, and $18.2 million and $17.2 million, respectively. The weighted-average discount rate and weighted average remaining lease term for operating leases was 4.3% and 4.4 years, respectively, as of December 31, 2020. The table below summarizes maturities of the Company’s operating lease liabilities as of December 31, 2020, which reconciles to total lease liabilities included in other liabilities on the Company’s consolidated balance sheet: Years ending December 31, (in thousands) 2021 $ 3,993 2022 3,800 2023 3,619 2024 2,422 2025 2,349 Thereafter 197 Total lease payments 16,380 Less imputed interest (1,464) Total operating lease liabilities $ 14,916 Operating lease liabilities include $10.3 million associated with office space in a building that is owned by a partnership in which the Company has a minority interest. Operating lease costs were $5.0 million, $5.2 million, and $4.6 million for the years ended December 31, 2020 , 2019, and 2018, respectively. Operating lease costs are primarily comprised of rental expense for operating leases. Rental expense is recognized on a straight line basis over the lease term and includes amortization of the right-of-use lease asset and imputed interest on the lease liability. Operating lease costs are included in other operating expenses in the Company's consolidated statements of income and comprehensive income.

Reserve for Losses and Loss Adj

Reserve for Losses and Loss Adjustment Expenses	12 Months Ended
	Dec. 31, 2020
Liability for Claims and Claims Adjustment Expense [Abstract]
Reserve for Losses and Loss Adjustment Expenses	Reserve for Losses and Loss Adjustment Expenses In establishing the reserve for losses and loss adjustment expenses, the Company’s internal actuaries estimate an initial expected ultimate loss ratio for each of our lines of business by accident year (or for our Casualty Reinsurance segment, on a contract by contract basis). Input from the Company’s underwriting and claims departments, including premium pricing assumptions and historical experience, are considered by the Company’s internal actuaries in estimating the initial expected loss ratios. The Company’s internal actuaries generally utilize five actuarial methods in their estimation process for the reserve for losses and loss adjustment expenses. These five methods utilize, to varying degrees, the initial expected loss ratio, detailed statistical analysis of past claims reporting and payment patterns, claims frequency and severity, paid loss experience, industry loss experience, and changes in market conditions, policy forms, exclusions, and exposures. In applying these methods to develop an estimate of the reserve for losses and loss adjustment expenses, our internal actuaries use judgment to determine three key parameters for each accident year and line of business: the initial expected loss ratios, the incurred and paid loss development factors and the weighting of the five actuarial methods to be used for each accident year and line of business. For the Excess and Surplus Lines and Specialty Admitted Insurance segments, the internal actuaries perform a study on each of these parameters annually and make recommendations for the initial expected loss ratios, the incurred and paid loss development factors and the weighting of the five actuarial methods by accident year and line of business. Members of management’s Reserve Committee review and approve the parameter review actuarial recommendations, and these approved parameters are used in the reserve estimation process for the next four quarters at which time a new parameter study is performed. For the Casualty Reinsurance segment, periodic assessments are made on a contract by contract basis with the goal of keeping the initial expected loss ratios and the incurred and paid loss development factors as constant as possible until sufficient evidence presents itself to support adjustments. Method weights are generally less rigid for the Casualty Reinsurance segment given the heterogeneous nature of the various contracts, and the potential for significant changes in mix of business within individual treaties. Different reserving methods are appropriate in different situations, and the Company’s internal actuaries use their judgment and experience to determine the weighting of the methods to use for each accident year and each line of business and, for our Casualty Reinsurance segment, on a contract by contract basis. For example, the current accident year has very little incurred and paid loss development data on which to base reserve projections. As a result, the Company relies heavily on the initial expected loss ratio in estimating reserves for the current accident year. The Company generally sets the initial expected loss ratio for the current accident year consistent with the internal actuaries’ pricing assumptions. We believe that this is a reasonable and appropriate reserving assumption for the current accident year since our pricing assumptions are actuarially driven and since the Company expects to make an acceptable return on the new business written. If actual loss emergence is better than our initial expected loss ratio assumptions, we will experience favorable development and if it is worse than our initial expected loss ratio assumptions, we will experience adverse development. Conversely, sufficient incurred and paid loss development data is available for the oldest accident years, so more weight is given to this development data and less weight is given to the initial expected loss ratio. The following table provides a reconciliation of the beginning and ending reserve balances for losses and loss adjustment expenses, net of reinsurance, to the gross amounts reported in the condensed consolidated balance sheets. Reinsurance recoverables on unpaid losses and loss adjustment expenses are presented gross of a $335,000 allowance for credit losses on reinsurance balances at December 31, 2020. Year Ended December 31, 2020 2019 2018 (in thousands) Reserve for losses and loss adjustment expenses net of reinsurance recoverables at beginning of period $ 1,377,461 $ 1,194,088 $ 989,825 Add: Incurred losses and loss adjustment expenses net of reinsurance: Current year 386,341 603,094 582,604 Prior years 92,204 69,008 17,672 Total incurred losses and loss and adjustment expenses 478,545 672,102 600,276 Deduct: Loss and loss adjustment expense payments net of reinsurance: Current year 31,952 75,249 86,355 Prior years 437,993 413,480 309,658 Total loss and loss adjustment expense payments 469,945 488,729 396,013 Reserve for losses and loss adjustment expenses net of reinsurance recoverables at end of period 1,386,061 1,377,461 1,194,088 Add: Reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period 806,019 668,045 467,371 Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period $ 2,192,080 $ 2,045,506 $ 1,661,459 The foregoing reconciliation shows that $92.2 million of adverse development was experienced in 2020 on the reserve for losses and loss adjustment expenses held at December 31, 2019. This adverse reserve development included $59.4 million of adverse development in the Excess and Surplus Lines segment including $91.4 million of adverse development in the commercial auto line of business that was primarily related to the 2018 and prior accident years with Rasier LLC and its affiliates (collectively, “Rasier”) . Rasier's business was new, complex, and rapidly changing, and the Company's underwriting assumptions and the related pricing of this risk did not keep pace with the insured's escalating loss trends. As a result of changes in the risk, unsatisfactory underwriting profits from the Rasier business, and a desire to refocus on the Company’s growing E&S core (non-commercial auto) lines of business where the Company has experienced many years of profitable underwriting results, on October 8, 2019, the Company delivered a notice of early cancellation to Rasier, effective December 31, 2019. The adverse development for commercial auto was partially offset by $32.0 million of favorable development in other Excess and Surplus Lines underwriting divisions that was primarily related to the 2018 and 2019 accident years. The Company also experienced $5.0 million of favorable development on prior accident years in the Specialty Admitted Insurance segment, as losses on our workers’ compensation business written prior to 2019 continued to develop more favorably than we had anticipated. The Casualty Reinsurance segment experienced $37.8 million of adverse development on prior accident years primarily in accident years 2014 through 2018. This adverse development was mainly in the general liability and commercial auto lines of business. The foregoing reconciliation shows that $69.0 million of adverse development was experienced in 2019 on the reserve for losses and loss adjustment expenses held at December 31, 2018. This adverse reserve development included $51.2 million of adverse development in the Excess and Surplus Lines segment including $57.4 million of adverse development in the commercial auto line of business that was primarily related to the 2016 and 2017 accident years with Rasier. The adverse development for commercial auto was partially offset by $6.2 million of favorable development in other Excess and Surplus Lines underwriting divisions. The Company also experienced $5.3 million of favorable development on prior accident years in the Specialty Admitted Insurance segment, as losses on our workers’ compensation business written prior to 2018 continued to develop more favorably than we had anticipated. The Casualty Reinsurance segment experienced $23.1 million of adverse development on prior accident years primarily in accident years 2011 through 2016. This adverse development was mainly in the general liability and commercial auto lines of business. The foregoing reconciliation shows that $17.7 million of adverse development was experienced in 2018 on the reserve for losses and loss adjustment expenses held at December 31, 2017. This adverse reserve development included $15.0 million of adverse development in the Excess and Surplus Lines segment, including $20.7 million of adverse development in the commercial auto line of business that was primarily related to the 2016 contract year with Rasier. The adverse development for commercial auto was partially offset by $5.7 million of favorable development in other Excess and Surplus Lines underwriting divisions primarily from favorable development in the Excess Property underwriting division related to the 2017 hurricanes. Favorable reserve development in the Specialty Admitted Insurance segment was $5.6 million and primarily came from accident years 2014 through 2016, as loss emergence on our workers’ compensation business written prior to 2016 continued to develop more favorably than we had anticipated. In addition, $8.2 million of adverse development occurred in the Casualty Reinsurance segment, with a majority of this adverse development coming from accident years at least four years old and treaties the Company has since non-renewed. The following tables present incurred and paid losses and loss adjustment expenses, net of reinsurance as of December 31, 2020 for: (1) the Excess and Surplus Lines segment split between all excess and surplus lines business excluding commercial auto, and separately, commercial auto, (2) the Specialty Admitted Insurance segment split between individual risk workers’ compensation and fronting and programs, and (3) the Casualty Reinsurance segment. The information provided herein about incurred and paid accident year claims development for the years ended December 31, 2019 and prior is presented as unaudited supplementary information. Excess and Surplus Lines — Excluding Commercial Auto Incurred losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 111,190 $ 119,927 $ 114,473 $ 106,564 $ 106,381 $ 106,130 $ 106,643 $ 106,536 $ 105,173 $ 104,280 2012 97,908 98,672 97,829 96,497 97,306 99,619 101,271 103,061 106,118 2013 96,729 96,064 85,433 81,009 82,830 83,855 82,732 82,517 2014 114,942 104,092 90,267 82,232 84,074 88,904 90,191 2015 126,443 113,417 104,847 102,434 103,688 110,466 2016 138,507 125,093 126,050 126,971 125,097 2017 144,349 131,897 132,136 124,265 2018 167,004 158,458 146,633 2019 214,653 194,759 2020 239,897 Total $ 1,324,223 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 27,684 $ 53,109 $ 72,732 $ 81,696 $ 90,884 $ 94,998 $ 98,684 $ 99,798 $ 101,728 $ 101,969 2012 6,944 33,757 49,604 63,216 74,869 82,545 88,812 94,588 99,628 2013 3,867 14,509 30,382 44,421 59,641 66,553 71,035 74,635 2014 3,412 16,969 28,212 43,891 58,774 71,549 76,523 2015 4,048 17,164 34,801 55,911 73,455 87,344 2016 5,180 22,852 46,045 70,105 90,166 2017 5,290 22,956 42,764 64,924 2018 6,000 26,160 50,679 2019 8,235 31,346 2020 8,642 Total $ 685,856 All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance (46 claims outstanding) $ 7,946 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 646,313 Excess and Surplus Lines — Commercial Auto Incurred losses and adjustment expenses, net of reinsurance (in thousands) Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2013 $ 1,255 $ 1,300 $ 1,451 $ 1,351 $ 1,301 $ 1,277 $ 1,277 $ 1,277 2014 20,487 14,071 17,233 18,953 19,779 18,303 19,196 2015 30,109 33,113 35,149 36,139 36,636 37,839 2016 74,340 109,286 126,791 147,122 157,712 2017 207,355 208,743 272,421 319,472 2018 255,881 230,220 283,408 2019 262,306 240,773 2020 19,133 Total $ 1,078,810 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2013 $ 60 $ 1,182 $ 1,285 $ 1,291 $ 1,275 $ 1,275 $ 1,275 $ 1,275 2014 6,166 8,645 12,679 16,359 18,678 17,745 18,301 2015 8,356 15,234 24,282 31,592 34,819 35,983 2016 18,295 54,054 89,381 125,108 141,545 2017 41,467 107,377 192,961 252,169 2018 45,136 119,099 184,686 2019 44,225 107,182 2020 628 Total $ 741,769 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 337,041 Specialty Admitted — Individual Risk Workers’ Compensation Incurred losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 37,834 $ 41,421 $ 40,154 $ 38,999 $ 38,311 $ 37,455 $ 36,594 $ 36,593 $ 36,593 $ 35,252 2012 32,116 32,420 31,490 29,689 28,255 28,174 28,186 28,186 27,741 2013 12,525 13,668 12,786 11,578 10,907 10,909 10,909 10,598 2014 16,638 16,652 14,620 13,890 12,704 12,704 12,573 2015 20,938 21,274 19,741 18,376 17,626 16,492 2016 21,678 20,299 18,050 15,800 14,050 2017 24,869 22,071 19,779 18,810 2018 16,432 16,288 16,038 2019 20,253 21,056 2020 20,137 Total $ 192,747 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 10,123 $ 23,127 $ 29,021 $ 33,204 $ 34,240 $ 34,287 $ 34,334 $ 34,614 $ 34,638 $ 34,665 2012 9,222 20,308 24,755 26,435 26,897 26,932 26,963 26,994 27,128 2013 4,487 8,723 9,846 10,246 10,263 10,309 10,337 10,335 2014 4,633 10,648 12,041 12,236 12,282 12,282 12,276 2015 6,604 13,285 15,118 15,889 15,901 16,068 2016 4,664 10,227 12,135 12,432 12,481 2017 6,546 12,782 14,285 15,195 2018 4,497 9,034 11,412 2019 5,473 13,776 2020 7,394 Total $ 160,730 All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance (4 claims outstanding) $ 1,237 Outstanding losses and loss adjustment expenses assumed from involuntary workers’ compensation pools $ 4,358 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 37,612 Specialty Admitted — Fronting and Programs Incurred losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2013 $ 104 $ 80 $ 52 $ 52 $ 52 $ 52 $ 52 $ 52 2014 3,460 3,468 3,818 3,425 3,228 3,083 3,081 2015 7,136 9,632 9,358 8,974 8,384 8,444 2016 11,542 15,670 14,682 15,522 14,468 2017 21,229 24,271 25,201 24,728 2018 21,758 20,677 19,822 2019 18,832 19,020 2020 25,433 Total $ 115,048 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2013 $ 28 $ 52 $ 52 $ 52 $ 52 $ 52 $ 52 $ 52 2014 883 1,687 2,369 2,728 2,854 2,916 2,917 2015 2,058 4,666 6,165 6,919 7,329 7,654 2016 1,894 5,123 6,888 10,732 10,896 2017 1,223 6,682 13,065 15,854 2018 885 4,972 10,495 2019 4,358 5,125 2020 5,375 Total $ 58,368 All outstanding losses and loss adjustment expenses, net of reinsurance $ 56,680 Outstanding losses and loss adjustment expenses, assumed from involuntary pools $ 601 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 57,281 Casualty Reinsurance Incurred losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 114,908 $ 103,123 $ 97,366 $ 97,812 $ 98,993 $ 99,282 $ 101,276 $ 103,196 $ 105,333 $ 106,226 2012 148,251 132,388 131,281 135,594 136,813 139,978 143,305 146,045 147,413 2013 133,230 130,361 131,352 134,446 137,801 143,124 146,760 149,682 2014 118,881 115,927 114,636 116,981 121,200 126,160 130,822 2015 119,157 108,870 108,699 109,117 114,517 120,185 2016 112,759 105,533 103,544 108,222 114,979 2017 134,628 128,472 129,800 138,831 2018 121,529 119,098 125,715 2019 86,022 85,549 2020 80,374 Total $ 1,199,776 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 48,688 $ 61,922 $ 68,616 $ 78,164 $ 87,267 $ 90,287 $ 94,627 $ 97,715 $ 99,511 $ 101,209 2012 73,124 81,859 97,215 113,943 121,026 128,567 133,606 137,430 139,719 2013 59,756 75,094 93,902 108,396 119,256 127,732 134,644 139,250 2014 41,421 58,601 76,302 89,899 101,366 110,374 117,971 2015 40,021 53,986 68,002 80,208 90,661 100,548 2016 36,268 50,905 65,409 78,145 90,356 2017 47,739 72,891 90,117 106,942 2018 30,903 50,274 69,123 2019 12,646 25,453 2020 5,589 Total $ 896,160 All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance $ 4,198 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 307,814 The reconciliation of the net incurred and paid claims development tables to the reserve for losses and loss adjustment expenses in the consolidated balance sheet at December 31, 2020 is as follows (in thousands): E&S – excluding commercial auto $ 646,313 E&S – commercial auto 337,041 Specialty Admitted – individual risk workers’ compensation 37,612 Specialty Admitted – fronting and programs 57,281 Casualty Reinsurance 307,814 Net reserve for losses and loss adjustment expenses 1,386,061 Reinsurance recoverables on unpaid losses (gross of $335,000 allowance for credit losses on reinsurance recoverables) 806,019 Gross reserve for losses and loss adjustment expenses $ 2,192,080 The following is unaudited supplementary information about average annual percentage payouts of incurred claims by age, net of reinsurance, for the Excess and Surplus Lines segment and the Specialty Admitted Insurance segments as of December 31, 2020. Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 E&S – excluding commercial auto 9.0 % 15.4 % 17.2 % 18.3 % 15.0 % 7.9 % 5.4 % 4.0 % 2.2 % 1.8 % E&S – commercial auto 18.2 % 38.3 % 16.4 % 13.7 % 7.7 % 3.0 % 0.3 % 2.3 % Specialty Admitted – individual risk workers’ compensation 27.1 % 31.6 % 15.3 % 9.0 % 6.3 % 3.4 % 2.2 % 1.2 % 1.2 % 0.8 % Specialty Admitted – fronting and programs 17.4 % 20.5 % 25.4 % 14.7 % 9.8 % 7.3 % 2.2 % 2.6 % Casualty Reinsurance 22.1 % 15.9 % 11.6 % 8.5 % 6.6 % 5.2 % 4.1 % 3.5 % 3.4 % 2.9 % In determining the cumulative number of reported claims, the Company measures claim counts by individual claimant for individual risk workers’ compensation policies in the Specialty Admitted Insurance segment. In the Excess and Surplus Lines insurance segment and for fronting and programs in the Specialty Admitted Insurance segment, the Company measures claim counts by claim event. The claim counts include all claims reported, even if the Company does not establish a liability for the claim (i.e. reserve for loss and loss adjustment expenses). The Casualty Reinsurance segment typically assumes written premium under quota share arrangements. The Company typically does not have direct access to claim frequency information underlying its assumed quota share arrangements given the nature of that business. In addition, multiple claims are often aggregated by the ceding company before being reported to the Company. We do not use claim frequency information in the Casualty Reinsurance segment in the determination of loss reserves or for other internal purposes. Based on these considerations, the Company does not believe providing claims frequency information is practicable as it relates to the Casualty Reinsurance segment. The table below provides information on IBNR liabilities and claims frequency for: (1) the Excess and Surplus Lines segment split between commercial auto and all non commercial auto, and (2) the Specialty Admitted Insurance segment split between individual risk workers’ compensation and fronting and programs: Excess and Surplus Lines — Excluding Commercial Auto Accident Year Incurred Losses IBNR Cumulative # of ($ in thousands) 2011 $ 104,280 $ 2,038 1,488 2012 106,118 1,586 1,850 2013 82,517 3,488 2,480 2014 90,191 6,804 2,198 2015 110,466 5,409 2,587 2016 125,097 15,213 3,023 2017 124,265 29,548 3,085 2018 146,633 52,940 4,267 2019 194,759 123,212 4,950 2020 239,897 206,389 3,115 Excess and Surplus Lines — Commercial Auto Accident Year Incurred Losses IBNR Cumulative # of ($ in thousands) 2013 $ 1,277 $ 1 54 2014 19,196 249 7,764 2015 37,839 639 41,766 2016 157,712 3,555 89,084 2017 319,472 4,303 134,055 2018 283,408 9,947 97,076 2019 240,773 40,372 70,707 2020 19,133 16,942 498 Specialty Admitted - Individual Risk Workers’ Compensation Accident Year Incurred Losses IBNR Cumulative # of ($ in thousands) 2011 $ 35,252 $ 532 $ 1,814 2012 27,741 602 1,323 2013 10,598 262 540 2014 12,573 298 850 2015 16,492 423 975 2016 14,050 1,527 836 2017 18,810 3,436 1,093 2018 16,038 4,020 1,238 2019 21,056 2,989 1,548 2020 20,137 2,842 1,305   Specialty Admitted — Fronting and Programs Accident Year Incurred Losses IBNR Cumulative # of ($ in thousands) 2013 $ 52 $ — 22 2014 3,081 150 858 2015 8,444 452 1,363 2016 14,468 1,900 2,815 2017 24,728 5,244 6,765 2018 19,822 4,998 7,318 2019 19,020 9,119 7,941 2020 25,433 14,743 6,956 The table below provides information on IBNR liabilities for the Casualty Reinsurance segment: Accident Year Incurred Losses IBNR ($ in thousands) 2011 $ 106,226 $ 819 2012 147,413 1,566 2013 149,682 2,427 2014 130,822 3,200 2015 120,185 5,147 2016 114,979 9,091 2017 138,831 17,173 2018 125,715 31,058 2019 85,549 49,717 2020 80,374 61,595 The Company has not provided insurance coverage that could reasonably be expected to produce material levels of asbestos claims activity. In addition, management does not believe that the Company is exposed to environmental liability claims other than those which it has specifically underwritten and priced as an environmental exposure.

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2020
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The Company remains liable to policyholders if its reinsurers are unable to meet their contractual obligations under applicable reinsurance agreements. To minimize exposure to significant losses from reinsurance insolvencies, the Company evaluates the financial condition of its reinsurers and monitors concentrations of credit risk. The Company’s reinsurance contracts generally require reinsurers that are not authorized as reinsurers under U.S. state insurance regulations or that experience rating downgrades from rating agencies below specified levels to fund their share of the Company’s ceded outstanding losses and loss adjustment expense reserves, typically through the use of irrevocable and unconditional letters of credit. In fronting arrangements, which the Company conducts through its Specialty Admitted Insurance segment, the Company is subject to credit risk with regard to insurance companies who act as reinsurers for the Company in such arrangements. The Company customarily requires a collateral trust arrangement to secure the obligations of the insurance entity for whom it is fronting. At December 31, 2020, the Company had reinsurance recoverables on unpaid losses of $805.7 million and reinsurance recoverables on paid losses of $46.1 million. All material reinsurance recoverables are from companies with A.M. Best Company ratings of “A-” (Excellent) or better, or are collateralized with letters of credit or by a trust agreement. At December 31, 2020, reinsurance recoverables on unpaid losses from the Company’s three largest reinsurers were $250.9 million, $83.1 million, and $51.4 million, representing 47.8% of the total balance. At December 31, 2020, prepaid reinsurance premiums ceded to three reinsurers totaled $72.0 million, $36.2 million, and $20.2 million, representing 52.7% of the total balance. Premiums written, premiums earned, and losses and loss adjustment expenses incurred are summarized as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Written premiums: Direct $ 1,103,994 $ 1,305,948 $ 1,027,222 Assumed 153,006 164,787 139,551 Ceded (609,226) (574,585) (404,101) Net $ 647,774 $ 896,150 $ 762,672 Earned premiums: Direct $ 1,005,138 $ 1,182,501 $ 990,221 Assumed 145,867 150,330 208,192 Ceded (544,199) (509,085) (383,015) Net $ 606,806 $ 823,746 $ 815,398 Losses and loss adjustment expenses: Direct $ 709,545 $ 953,548 $ 769,490 Assumed 125,096 113,843 131,346 Ceded (356,096) (395,289) (300,560) Net $ 478,545 $ 672,102 $ 600,276

Senior Debt

Senior Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Senior Debt	Senior Debt The Company has a $315.0 million senior revolving credit facility (as amended or amended and restated, the "2013 Facility”). The 2013 Facility is comprised of the following at December 31, 2020: • A $102.5 million secured revolving facility utilized by JRG Re to issue letters of credit for the benefit of third-party reinsureds. This portion of our credit facility is secured by our investment securities. At December 31, 2020, the Company had $92.0 million of letters of credit issued under the secured facility. • A $212.5 million unsecured revolving facility to meet the working capital needs of the Company. All unpaid principal on the revolver is due at maturity. Interest accrues quarterly and is payable in arrears at LIBOR plus a margin which at December 31, 2020 was 1.500%, which is subject to change according to terms in the credit agreement. At December 31, 2020 and 2019, the Company had a drawn balance of $185.8 million and $133.3 million, respectively, outstanding on the unsecured revolver. The $52.5 million of additional borrowings in 2020 were used to support our growth and for general corporate purposes. James River Group Holdings, Ltd. and JRG Re are borrowers on the 2013 Facility. The 2013 Facility has been amended from time to time since its inception in 2013. On November 8, 2019, the Company entered into a Second Amended and Restated Credit Agreement for the 2013 Facility which, among other things, extended the maturity date of the 2013 Facility until November 8, 2024, increased the amount available under the unsecured revolving credit facility to $212.5 million, lowered the applicable interest rate and letter of credit fees, and modified certain negative covenants to be less restrictive. A subsidiary of the Bank Holding Company is one of the lenders for the 2013 Facility, with a $36.0 million commitment allocation on the total $315.0 million 2013 Facility. The 2013 Facility contains certain financial and other covenants (including minimum net worth, maximum ratio of total adjusted debt outstanding to total capitalization, and financial strength ratings) with which the Company was in compliance, at December 31, 2020. On August 2, 2017, the Company and its wholly-owned subsidiary, JRG Re, together as borrowers, entered into a credit agreement (the "2017 Facility") that provides the Company with a revolving line of credit of up to $100.0 million, which may be used for loans and letters of credit made or issued, at the borrowers' option, on a secured or unsecured basis. The loans and letters of credit made or issued under the revolving line of credit may be used to finance the Borrowers’ general corporate purposes. On November 8, 2019, the Company entered into a First Amendment to Credit Agreement which, among other things, lowered the applicable interest rate and modified certain negative covenants to be less restrictive. Obligations under the 2017 Facility carry a variable rate of interest subject to terms in the credit agreement and will mature 30 days after notice of termination from the lender. Interest accrues quarterly and is payable in arrears at variable rates which are subject to change according to terms in the credit agreement. At December 31, 2020, unsecured loans of $61.5 million and secured letters of credit totaling $17.5 million were outstanding under the facility. During 2020, we borrowed an additional $51.5 million in unsecured loans to support our growth and for general corporate purposes. In order to secure borrowings and letters of credit made or issued under the secured portion of the revolving line of credit, JRG Re entered into a pledge and security agreement on August 2, 2017 with the lender, pursuant to which JRG Re will pledge certain investment securities. In the event the Company elects to pledge investment securities as collateral for the secured portion of the revolving credit facility, the Company will enter into a similar pledge and security agreement. The lender under the credit agreement and its affiliate is a joint bookrunner and joint lead arranger under the Company’s Second Amended and Restated Credit Agreement dated as of November 8, 2019, as amended, and its affiliate was also an underwriter in the December 2014 initial public offering of the Company’s common shares. The 2017 Facility contains certain financial and other covenants which we are in compliance with at December 31, 2020. On May 26, 2004, James River Group issued $15.0 million of unsecured, floating rate senior debentures (the “Senior Debt”), due April 29, 2034 unless accelerated earlier, through an indenture. The Senior Debt is not redeemable by the holder and is not subject to sinking fund requirements. Interest accrues quarterly and is payable in arrears at a per annum rate of the three-month LIBOR on the Determination Date (as defined in the indenture) plus 3.85%. The Senior Debt is redeemable prior to its stated maturity in whole or in part, at the option of James River Group. The terms of the indenture generally provide that so long as the Senior Debt is outstanding, neither James River Group nor any of its subsidiaries may: • assume or permit to exist any indebtedness that is secured by any encumbrance on the capital stock of James River Group or any of its subsidiaries which is senior to the Senior Debt; or • issue, sell, transfer or otherwise dispose of any shares of, securities convertible into, or warrants, rights or options to subscribe for or purchase shares of, capital stock of any subsidiary. The terms of the Senior Debt contain certain covenants, with which we are in compliance at December 31, 2020, and which, among other things, restrict our ability to assume senior indebtedness secured by our U.S. holding company's common stock or its subsidiaries' capital stock or to issue shares of its subsidiaries' capital stock. Interest payable is included in “accrued expenses” in the accompanying consolidated balance sheets.

Junior Subordinated Debt

Junior Subordinated Debt	12 Months Ended
	Dec. 31, 2020
Subordinated Borrowings [Abstract]
Junior Subordinated Debt	Junior Subordinated Debt The Company issued trust preferred securities (“Trust Preferred Securities”) through James River Capital Trust I, James River Capital Trust II, James River Capital Trust III, James River Capital Trust IV, and Franklin Holdings II (Bermuda) Capital Trust I, (each, a “Trust”; collectively, the “Trusts”). These Delaware statutory trusts are sponsored and wholly-owned by the Company. Each Trust was created solely for the purpose of issuing the Trust Preferred Securities. Each Trust used proceeds from the sale of its Trust Preferred Securities to purchase the Company’s floating rate junior subordinated debentures (the “Junior Subordinated Debt”) issued to the Trust under an indenture (each, an “Indenture”; collectively, the “Indentures”). The Junior Subordinated Debt is the sole asset of each Trust, and the Trust Preferred Securities are the sole liabilities of each Trust. The Company purchased all of the outstanding common stock of the Trusts, and the investment in the Trusts is included in “other assets” in the accompanying consolidated balance sheets.   The following table summarizes the nature and terms of the Junior Subordinated Debt and Trust Preferred Securities: James River James River James River James River Franklin ($ in thousands) Issue date May 26, December 15, June 15, December 11, January 10, Principal amount of Trust Preferred Securities $7,000 $15,000 $20,000 $54,000 $30,000 Principal amount of Junior Subordinated Debt $7,217 $15,464 $20,619 $55,670 $30,928 Carrying amount of Junior Subordinated Debt net of repurchases $7,217 $15,464 $20,619 $44,827 $15,928 Maturity date of Junior Subordinated Debt, unless accelerated earlier May 24, December 15, June 15, December 15, March 15, Trust common stock $217 $464 $619 $1,670 $928 Interest rate, per annum Three-Month LIBOR plus 4.0% Three-Month LIBOR plus 3.4% Three-Month LIBOR plus 3.0% Three-Month LIBOR plus 3.1% Three-Month LIBOR plus 4.0% All of the Junior Subordinated Debt is currently redeemable at 100.0% of the unpaid principal amount at the Company’s option. Interest on the Trust Preferred Securities and interest paid to the Trusts on the Junior Subordinated Debt is payable quarterly in arrears at a per annum rate as described in the table above. The Company has the right to defer interest payments on the Junior Subordinated Debt for up to five years without triggering an event of default. The Trust Preferred Securities are subject to mandatory redemption in a like amount (a) upon repayment of all of the Junior Subordinated Debt on the stated maturity date, (b) contemporaneously with the optional prepayment of all of the Junior Subordinated Debt in conjunction with a special event (as defined), and (c) five years or more after the issue date, contemporaneously with the optional prepayment, in whole or in part, of the Junior Subordinated Debt. The Indentures contain certain covenants which the Company is in compliance with as of December 31, 2020. Interest payable is included in “accrued expenses” on the accompanying consolidated balance sheets.

Capital Stock

Capital Stock	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
Capital Stock	Capital Stock The Company’s authorized share capital consists of 200,000,000 common shares, par value $0.0002 per share (30,649,261 shares issued and outstanding at December 31, 2020) and 20,000,000 undesignated preferred shares, par value $0.00125 per share (no shares issued or outstanding). Share activity in 2019 and 2020 includes issuances from stock option exercises and RSU vesting, increasing the number of common shares outstanding from 29,988,460 at December 31, 2018 to 30,424,391 at December 31, 2019 and 30,649,261 at December 31, 2020. The Company has 4,321,150 common shares reserved for future issuance upon exercise or vesting of equity awards, as applicable. The Board of Directors declared the following cash dividends in 2020, 2019, and 2018: Date of Dividend per Payable to Shareholders Payment Date Total Amount (thousands) 2020 February 19, 2020 $0.30 March 16, 2020 March 31, 2020 $ 9,269 April 28, 2020 $0.30 June 15, 2020 June 30, 2020 $ 9,271 July 28, 2020 $0.30 September 14, 2020 September 30, 2020 $ 9,292 October 27, 2020 $0.30 December 14, 2020 December 31, 2020 $ 9,305 Total $1.20 $ 37,137 2019 February 20, 2019 $0.30 March 11, 2019 March 29, 2019 $ 9,146 April 30, 2019 $0.30 June 10, 2019 June 28, 2019 $ 9,205 July 30, 2019 $0.30 September 16, 2019 September 30, 2019 $ 9,231 November 5, 2019 $0.30 December 16, 2019 December 31, 2019 $ 9,229 Total $1.20 $ 36,811 2018 February 22, 2018 $0.30 March 12, 2018 March 30, 2018 $ 9,049 May 1, 2018 $0.30 June 11, 2018 June 29, 2018 $ 9,066 August 1, 2018 $0.30 September 10, 2018 September 28, 2018 $ 9,081 November 7, 2018 $0.30 December 14, 2018 December 28, 2018 $ 9,089 Total $1.20 $ 36,285 Included in the dividends are $449,000, $433,000 and $391,000 of dividend equivalents on RSUs, of which $663,000, $623,000 and $557,000 were payable as of December 31, 2020, 2019, and 2018, respectively.

Equity Awards

Equity Awards	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Equity Awards	Equity Awards Equity Incentive Plans The Company’s shareholders have approved various equity incentive plans, including the Amended and Restated 2009 Equity Incentive Plan (the “Legacy Plan”), the 2014 Long Term Incentive Plan (“2014 LTIP”), and the 2014 Non-Employee Director Incentive Plan (“2014 Director Plan”) (collectively, the “Plans”). All awards issued under the Plans are issued at the discretion of the Board of Directors. Under the Legacy Plan, employees received non-qualified stock options. There are no options outstanding under the Legacy Plan as of December 31, 2020 and no additional awards may be granted. Employees are eligible to receive non-qualified stock options, incentive stock options, share appreciation rights, performance shares, restricted shares, RSUs, and other awards under the 2014 LTIP. The maximum number of shares available for issuance under the 2014 LTIP is 4,171,150, and at December 31, 2020, 1,357,375 shares are available for grant. Non-employee directors of the Company are eligible to receive non-qualified stock options, share appreciation rights, performance shares, restricted shares, RSUs, and other awards under the 2014 Director Plan. At the 2019 Annual General Meeting of Shareholders of the Company held on April 30, 2019, the Company's shareholders approved an amendment to the 2014 Director Plan. The Board of Directors of the Company had previously approved the amendment. The amendment increased the number of the Company's common shares authorized for issuance under the 2014 Director Plan by 100,000 shares. The maximum number of shares available for issuance under the 2014 Director Plan is 150,000, and at December 31, 2020, 101,746 shares are available for grant. Generally, awards issued under the 2014 LTIP and 2014 Director Plan vest immediately in the event that an award recipient is terminated without Cause (as defined), and in the case of the 2014 LTIP for Good Reason (as defined), at any time following a Change in Control (as defined in the applicable plans). Options The following table summarizes the option activity: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding: Beginning of year 643,851 $ 30.41 1,115,324 $ 29.02 1,479,236 $ 27.81 Granted — $ — — $ — — $ — Exercised (180,527) $ 25.70 (459,415) $ 26.87 (308,025) $ 22.01 Forfeited — $ — (12,058) $ 36.84 (55,887) $ 35.69 End of year 463,324 $ 32.25 643,851 $ 30.41 1,115,324 $ 29.02 Exercisable, end of year 463,324 $ 32.25 590,340 $ 29.34 814,421 $ 26.46 All of the outstanding options vest over three years and have a contractual life of seven years from the original date of grant. All of the outstanding options have an exercise price equal to the fair value of the underlying shares at the date of grant. The intrinsic value of each option is determined based on the difference between the fair value of the underlying share and the exercise price of the underlying option. The total intrinsic value of options exercised during 2020, 2019 and 2018 was $3.8 million, $8.2 million and $4.6 million, respectively. The aggregate intrinsic value of options outstanding at December 31, 2020, 2019 and 2018 was $7.8 million, $7.1 million and $9.4 million, respectively. The aggregate intrinsic value of options exercisable at December 31, 2020, 2019 and 2018 was $7.8 million, $7.1 million and $8.5 million, respectively. The fair value used for calculating intrinsic values was $49.15, $41.21 and $36.54 at December 31, 2020, 2019 and 2018, respectively. The weighted-average remaining contractual life of the options outstanding and exercisable at December 31, 2020 is 2.1 years. There were no options granted in 2020, 2019, or 2018. The value of the options granted was estimated at the date of grant using the Black-Scholes-Merton option pricing model. RSUs The following table summarizes RSU activity: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Unvested, beginning of year 340,368 $ 41.50 300,142 $ 39.22 178,882 $ 37.93 Granted 272,608 $ 45.11 197,078 $ 42.56 227,481 $ 39.74 Vested (165,344) $ 41.49 (134,407) $ 37.99 (83,384) $ 37.61 Forfeited (47,776) $ 44.57 (22,445) $ 41.32 (22,837) $ 40.21 Unvested, end of year 399,856 $ 43.59 340,368 $ 41.50 300,142 $ 39.22 The vesting period of RSUs granted to employees range from one Compensation Expense Share based compensation expense is recognized on a straight line basis over the vesting period. The amount of expense and related tax benefit is summarized below: Year Ended December 31, 2020 2019 2018 (in thousands) Share based compensation expense $ 7,625 $ 7,178 $ 6,228 U.S. tax benefit on share based compensation expense $ 1,001 $ 872 $ 716 As of December 31, 2020, the Company had $11.1 million of unrecognized share based compensation expense expected to be charged to earnings over a weighted-average period of 2.1 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Under current Bermuda law, James River Group Holdings, Ltd. and its Bermuda based subsidiaries, JRG Re and Carolina Re, are not required to pay any Bermuda taxes on their income or capital gains. Those companies have received an undertaking from the Minister of Finance in Bermuda that, in the event of any taxes being imposed, the Company will be exempt from taxation in Bermuda until March 2035. Distributions from the Company’s U.S. subsidiaries to its U.K. intermediate holding company, James River UK, are generally subject to a 5% dividend withholding tax. No distributions occurred in 2020, 2019 or 2018. The Company’s U.S. subsidiaries are subject to federal, state and local corporate income taxes, and other taxes applicable to U.S. corporations. In addition, Carolina Re is subject to Federal income taxes as a result of its irrevocable election to be taxed as a U.S. domestic corporation under Section 953(d) of the Code. The Company’s U.S.-domiciled subsidiaries and Carolina Re file a consolidated U.S. federal income tax return. The Company’s U.S.-based subsidiaries are generally no longer subject to income tax examination by U.S. income tax authorities for the tax years ending before January 1, 2017. Financial results for 2018 reflect the changes in loss reserve discounting required by the 2017 Tax Act. During 2018, the IRS published factors that allowed the Company to adjust its current and deferred tax liabilities based on the provisions of the Tax Act. The Tax Act has specific transition provisions associated with reserve discounting. The initial impact of the proposed regulations in 2018 was an increase to our deferred tax asset for the additional discount as of December 31, 2017 of $8.8 million offset by an increase to our deferred tax liability of $8.8 million representing the 8 year transition provision required by the Tax Act. During 2018, $1.1 million of this transition provision was recognized in our current provision and adjusted out of our deferred tax liability. The regulations were finalized in 2019, and the remaining reserve adjustment at December 31, 2019 based on these final regulations is $5.7 million to be recognized over the next six years at $950,000 per year. There were other provisions of the Tax Act for which the Company finalized its estimates during 2018, and the impact of these was immaterial. The expected income tax provision computed from pre-tax income at the weighted-average tax rate has been calculated as the sum of the pre-tax income in each jurisdiction multiplied by that jurisdiction’s applicable Federal statutory tax rate. Federal statutory tax rates of 0% and 21% have been used in 2020, 2019 and 2018 for Bermuda and the U.S., respectively. U.S. income before Federal income taxes was $25.1 million, $70.7 million, and $37.5 million for the years ending December 31, 2020, 2019, and 2018, respectively. The Tax Act base-erosion and anti-abuse tax (“BEAT”) provisions impose a minimum tax on applicable taxpayers that make certain payments to related foreign persons. BEAT subjects the modified taxable income of an applicable taxpayer to a specified tax rate (10% in 2020). Modified taxable income is generally calculated by adding back certain payments to related foreign persons to regular taxable income. For the Company, reinsurance premiums paid by the Company’s U.S. insurance subsidiaries to JRG Re, a Bermuda entity that is not a U.S. taxpayer, are added back to regular taxable income in applying the BEAT provisions. A reconciliation of the difference between the Company’s Federal income tax provision on U.S. income and the expected Federal tax provision on U.S. income using the weighted-average tax rate as well as a reconciliation to total tax expense is as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Federal income tax expense at applicable statutory rates $ 5,272 $ 14,843 $ 7,875 Tax-exempt investment income (260) (230) (272) Dividends received deduction (283) (307) (307) Excess tax benefits on share based compensation (679) (1,099) (567) Effect of tax rate reduction on deferred tax liability — — 220 Base Erosion and Anti-Abuse Tax 2,843 — — Other 17 99 145 Federal income tax expense $ 6,910 $ 13,306 $ 7,094 U.S. state income tax expense (benefit) 203 222 (86) Total income tax expense $ 7,113 $ 13,528 $ 7,008 The significant components of net deferred tax assets (liabilities) at the corporate income tax rate of 21% for the years ended December 31, 2020 and 2019 are summarized as follows: December 31, 2020 2019 (in thousands) Deferred tax assets: Accrued compensation expenses $ 2,308 $ 2,563 Reserve for losses and loss adjustment expenses 14,265 12,286 Unearned premiums 9,753 8,226 Share based compensation 1,427 1,482 Allowance for doubtful accounts 2,130 1,188 Property and equipment 213 16 Other 4,810 1,974 Total deferred tax assets 34,906 27,735 Deferred tax liabilities: Intangible assets 7,324 7,381 Net unrealized gains 12,201 5,792 Deferred policy acquisition costs 4,786 4,448 Equity method investments 8,839 9,316 Other 2,861 134 Total deferred tax liabilities 36,011 27,071 Net deferred tax (liabilities) assets $ (1,105) $ 664 Deferred income taxes have not been accrued with respect to certain undistributed earnings of foreign subsidiaries. If the earnings were to be distributed, as dividends or otherwise, such amounts may be subject to withholding taxation in the jurisdiction of the paying entity. The Company asserts that U.S. unremitted earnings as of December 31, 2020 will be permanently reinvested in the U.S. and, accordingly, no provision for withholding taxes arising in respect to U.S. unremitted earnings has been made. The Company had no reserve for future tax contingencies or liabilities (“unrecognized tax benefits”) at December 31, 2020 or 2019. The U.S. imposes a 1% excise tax on reinsurance premiums paid to non-U.S. reinsurers with respect to risks located in the U.S. The rates of tax are established based on the nature of the risk, unless reduced by an applicable U.S. tax treaty. For the years ended December 31, 2020, 2019, and 2018, the Company paid $468,000, $586,000, and $823,000, respectively, of federal

Other Operating Expenses and Ot

Other Operating Expenses and Other Expenses	12 Months Ended
	Dec. 31, 2020
Other Operating Expenses And Other Expenses [Abstract]
Other Operating Expenses and Other Expenses	Other Operating Expenses and Other Expenses Other operating expenses consist of the following: Year Ended December 31, 2020 2019 2018 (in thousands) Amortization of policy acquisition costs $ 75,578 $ 83,893 $ 111,103 Other underwriting expenses of the insurance segments 60,502 59,351 63,029 Other operating expenses of the Corporate and Other segment 29,418 27,664 26,903 Total $ 165,498 $ 170,908 $ 201,035 Other expenses consist of the following: Year Ended December 31, 2020 2019 2018 (in thousands) Employee severance $ 1,967 $ 1,055 $ 1,386 Income on leased building the Company was previously deemed to own for accounting purposes — — (623) Legal and professional services related to secondary share offerings — — 337 Other 171 — — Impairment of intangible asset — — 200 Total $ 2,138 $ 1,055 $ 1,300

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Employee Benefits	Employee BenefitsThe Company and its subsidiaries offer savings plans (the “Savings Plans”) which qualify under Section 401(k) of the U.S. Internal Revenue Code. Participants may contribute certain percentages of their pre-tax salary to the Savings Plans subject to statutory limitations. The Company and its subsidiaries match employee contributions at various rates up to a maximum contribution of 6.0% of the participant’s earnings subject to certain statutory limits. For the years ended December 31, 2020, 2019, and 2018, the expense associated with the Savings Plans totaled $3.5 million, $3.2 million, and $2.9 million, respectively.

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Commitments and Contingent Liabilities The Company is involved in legal proceedings, including commercial matters and litigation regarding insurance claims arising in the ordinary course of its operations. The Company believes that the ultimate resolution of these matters will not materially impact its financial position, cash flows, or results of operations. The Company’s reinsurance subsidiary, JRG Re, entered into three letter of credit facilities with banks as security to third-party reinsureds on reinsurance assumed by JRG Re. JRG Re has established custodial accounts to secure these letters of credit. Under a $75.0 million facility, $7.3 million of letters of credit were issued through December 31, 2020 which were secured by deposits of $14.6 million. Under the 2013 Facility, $92.0 million of letters of credit were issued through December 31, 2020 which were secured by deposits of $115.7 million. Under the 2017 Facility, $17.5 million of letters of credit were issued through December 31, 2020 which were secured by deposits of $28.4 million. JRG Re has also established trust accounts to secure its obligations to selected reinsureds. The total amount deposited in the trust accounts for the benefit of third-party reinsureds was $304.6 million at December 31, 2020. The Company previously issued a set of insurance contracts to Rasier under which the Company pays losses and loss adjustment expenses on the contracts. The Company has indemnity agreements with Rasier (non-insurance entities) and is contractually entitled to receive reimbursement for a significant portion of the losses and loss adjustment expenses paid on behalf of Rasier and other expenses incurred by the Company. Rasier is required to collateralize all amounts currently due to the Company and to provide additional collateral sufficient to cover the amounts that may be recoverable under the indemnity agreements, including, among other things, case loss and loss adjustment expense reserves, IBNR loss and loss adjustment expense reserves, extra contractual obligations and excess of policy limits liabilities. The collateral is provided through a collateral trust arrangement established in favor of the Company by a captive insurance company affiliate of Rasier. As permitted under our indemnification agreements with Rasier and the associated trust agreement, we have withdrawn the collateral posted to the trust account. At December 31, 2020, the Company held collateral funds of $859.9 million. The funds withdrawn from the trust account, currently invested in short term U.S. Treasury securities and included in restricted cash equivalents on the Company's consolidated balance sheet, will be used to reimburse the Company for the losses and loss adjustment expenses paid on behalf of Rasier and other related expenses incurred by the Company to the extent not paid as required under the indemnity agreements. The Company has ongoing exposure to estimated losses and expenses on these contracts growing at a faster pace than growth in our collateral balances. In addition, we have credit exposure if our estimates of future losses and loss adjustment expenses and other amounts recoverable, which are the basis for establishing collateral balances, are lower than actual amounts paid or payable. The amount of our credit exposure in any of these instances could be material. To mitigate these risks, we closely and frequently monitor our exposure compared to our collateral held, and we request additional collateral when our analysis indicates that we have uncollateralized exposure.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2020
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) The following table summarizes the components of other comprehensive income (loss): Year Ended December 31, 2020 2019 2018 (in thousands) Unrealized gains (losses) arising during the period, before U.S. income taxes $ 58,704 $ 51,381 $ (23,201) U.S. income taxes (6,967) (3,510) 483 Unrealized gains (losses) arising during the period, net of U.S. income taxes 51,737 47,871 (22,718) Less reclassification adjustment: Net realized investment gains (losses) 1,045 1,081 (554) U.S. income taxes (93) (152) 39 Reclassification adjustment for investment gains (losses) realized in net income 952 929 (515) Other comprehensive income (loss) $ 50,785 $ 46,942 $ (22,203) In addition to the net realized investment gains (losses) of $1.0 million, $1.1 million, and $(554,000) on available-for-sale fixed maturity securities for the years ended December 31, 2020, 2019, and 2018, the Company recognized net realized and unrealized investment gains (losses) in the respective years of $(15.4) million, $(10.1) million, and $1.1 million on its investments in bank loan participations and $(1.7) million, $6.0 million, and $(6.0) million on its investments in equity securities.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segment Information	Segment Information The Company has four reportable segments, three of which are separately managed business units and the fourth (“Corporate and Other”) includes the Company’s remaining operations. The Excess and Surplus Lines segment primarily offers commercial excess and surplus lines liability and excess property insurance products. The Specialty Admitted Insurance segment offers workers’ compensation insurance coverage as well as specialty admitted fronting and program business. The Casualty Reinsurance segment offers commercial liability and non-catastrophe property reinsurance to U.S. insurance companies and to the Company’s U.S.-based insurance subsidiaries. The Corporate and Other segment consists of certain management and treasury activities of James River Group, James River UK, and JRG Holdings as well as interest expense associated with senior debt and Junior Subordinated Debt, and investment income from investments classified as other invested assets. The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies. Segment revenues for each reportable segment consist of net earned premiums, net investment income, and realized and unrealized (losses) gains on investments. Segment profit (loss) for each reportable segment is measured by underwriting profit (loss), which is generally defined as net earned premiums less losses and loss adjustment expenses and other operating expenses of the operating segments. Gross fee income of the Excess and Surplus Lines segment and Specialty Admitted Insurance segment is included in the respective segment’s underwriting profit (loss). Gross fee income of $3.4 million ($1.6 million from the Excess and Surplus Lines segment and $1.8 million from the Specialty Admitted Insurance segment), $9.5 million ($9.1 million from the Excess and Surplus Lines segment and $421,000 from the Specialty Admitted Insurance segment) and $13.9 million (all from the Excess and Surplus Lines segment) was included in other income and in underwriting profit for the years ended December 31, 2020, 2019 and 2018, respectively. Segment results are reported prior to the effects of the intercompany reinsurance agreements between the Company’s insurance subsidiaries. All gross written premiums and net earned premiums for all periods presented were generated from policies issued to U.S. based insureds. Excess and Specialty Casualty Corporate Total (in thousands) As of and for the Year Ended December 31, 2020 Gross written premiums $ 699,143 $ 408,691 $ 149,166 $ — $ 1,257,000 Net earned premiums 415,168 57,505 134,133 — 606,806 Segment revenues 429,918 62,790 166,837 9,144 668,689 Net investment income 18,664 3,392 42,554 8,758 73,368 Interest expense — — — 10,033 10,033 Underwriting profit (loss) of operating segments 9,752 4,185 (18,364) — (4,427) Segment goodwill 181,831 — — — 181,831 Segment assets 2,208,344 907,604 1,899,328 47,796 5,063,072 As of and for the Year Ended December 31, 2019 Gross written premiums $ 922,320 $ 387,642 $ 160,773 $ — $ 1,470,735 Net earned premiums 625,528 54,338 143,880 — 823,746 Segment revenues 657,501 61,241 183,700 4,683 907,125 Net investment income 21,358 3,802 46,325 4,167 75,652 Interest expense — — — 10,596 10,596 Underwriting profit (loss) of operating segments 19,157 5,913 (7,161) — 17,909 Segment goodwill 181,831 — — — 181,831 Segment assets 2,481,934 786,433 1,699,473 56,565 5,024,405 As of and for the Year Ended Gross written premiums $ 656,538 $ 374,346 $ 135,889 $ — $ 1,166,773 Net earned premiums 555,684 55,146 204,568 — 815,398 Segment revenues 580,785 56,717 243,178 4,919 885,599 Net investment income 14,456 3,262 38,838 4,700 61,256 Interest expense — — — 11,553 11,553 Underwriting profit of operating segments 42,834 6,972 5,103 — 54,909 Segment goodwill 181,831 — — — 181,831 Segment assets 972,111 633,689 1,453,754 77,222 3,136,776 The following table reconciles the underwriting (loss) profit of operating segments by individual segment to income before income taxes: Year Ended December 31, 2020 2019 2018 (in thousands) Underwriting (loss) profit of the operating segments: Excess and Surplus Lines $ 9,752 $ 19,157 $ 42,834 Specialty Admitted Insurance 4,185 5,913 6,972 Casualty Reinsurance (18,364) (7,161) 5,103 Total underwriting (loss) profit of operating segments (4,427) 17,909 54,909 Other operating expenses of the Corporate and Other segment (29,418) (27,664) (26,903) Underwriting (loss) profit (33,845) (9,755) 28,006 Net investment income 73,368 75,652 61,256 Net realized and unrealized losses on investments (16,030) (2,919) (5,479) Other income 1,153 1,137 505 Other expenses (2,138) (1,055) (1,300) Interest expense (10,033) (10,596) (11,553) Amortization of intangible assets (538) (597) (597) Income before income taxes $ 11,937 $ 51,867 $ 70,838 The Company currently has 15 underwriting divisions, including 13 in the Excess and Surplus Lines segment, one in the Specialty Admitted Insurance segment, and one in the Casualty Reinsurance segment. Each underwriting division focuses on a specific industry group or coverage. Gross written premiums by segment and underwriting division are presented below: Year Ended December 31, 2020 2019 2018 (in thousands) Excess Casualty $ 213,037 $ 118,954 $ 66,452 General Casualty 125,433 115,832 54,127 Manufacturers and Contractors 122,880 105,096 79,160 Energy 51,109 45,442 33,942 Excess Property 37,332 31,606 16,963 Life Sciences 35,163 24,462 16,636 Commercial Auto 30,029 405,565 322,126 Allied Health 26,918 26,713 30,450 Small Business 24,790 19,725 14,808 Environmental 17,753 16,539 10,499 Professional Liability 6,881 6,441 5,916 Sports and Entertainment 6,118 4,212 3,685 Medical Professionals 1,700 1,733 1,774 Total Excess and Surplus Lines segment 699,143 922,320 656,538 Specialty Admitted Insurance segment 408,691 387,642 374,346 Casualty Reinsurance segment 149,166 160,773 135,889 Total $ 1,257,000 $ 1,470,735 $ 1,166,773 The Company does business with three brokers that generated $165.8 million, $157.5 million and $128.9 million of gross written premiums for the Excess and Surplus Lines segment for the year ended December 31, 2020, representing 13.2%, 12.5% and 10.3% of consolidated gross written premiums and 23.7%, 22.5% and 18.4% of the Excess and Surplus Lines segment’s gross written premiums, respectively. The Company has agency contracts with various branches within the aforementioned brokers. No other broker generated 10.0% or more of the gross written premiums for the Excess and Surplus Lines segment for the year ended December 31, 2020. No individual insured generated 10.0% or more of the gross written premiums for the Excess and Surplus Lines segment for the year ended December 31, 2020. The Specialty Admitted Insurance segment accepts applications for insurance from a variety of sources, including independent retail agents, program administrators and managing general agents (“MGAs”). The Company does business with two agencies that generated $125.5 million (Atlas General Insurance Services) and $46.4 million of gross written premiums for the Specialty Admitted Insurance segment for the year ended December 31, 2020, representing 10.0% and 3.7% of the consolidated gross written premiums and 30.7% and 11.4% of the Specialty Admitted Insurance segment’s gross written premiums, respectively. No other agency generated 10.0% or more of the gross written premiums for the Specialty Admitted Insurance segment for the year ended December 31, 2020. The Company does business with three brokers that generated $55.8 million, $34.9 million, and $22.4 million of gross written premiums for the Casualty Reinsurance segment for the year ended December 31, 2020, representing 4.4%, 2.8%, and 1.8% of consolidated gross written premiums and 37.4%, 23.4%, and 15.0% of the Casualty Reinsurance segment’s gross written premiums, respectively. No other broker generated 10.0% or more of the gross written premiums for the Casualty Reinsurance segment for the year ended December 31, 2020. The Casualty Reinsurance segment assumed business from three unaffiliated ceding companies that generated $85.1 million, $23.1 million, and $19.1 million of gross written premiums for the year ended December 31, 2020, representing 6.8%, 1.8%, and 1.5% of consolidated gross written premiums and 57.0%, 15.5%, and 12.8% of the Casualty Reinsurance segment’s gross written premiums, respectively.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Three levels of inputs are used to measure fair value of financial instruments: (1) Level 1: quoted price (unadjusted) in active markets for identical assets, (2) Level 2: inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the instrument, and (3) Level 3: inputs to the valuation methodology are unobservable for the asset or liability. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The fair values of fixed maturity securities, equity securities, and bank loan participations have been determined using fair value prices provided by the Company's investment accounting services provider or investment managers, who utilize internationally recognized independent pricing services. The prices provided by the independent pricing services are generally based on observable market data in active markets ( e.g. broker quotes and prices observed for comparable securities). Values for U.S. Treasury and publicly-traded equity securities are generally based on Level 1 inputs which use the market approach valuation technique. The values for all other fixed maturity securities (including state and municipal securities and obligations of U.S. government corporations and agencies) and bank loan participations generally incorporate significant Level 2 inputs, and in some cases, Level 3 inputs, using the market approach and income approach valuation techniques. There have been no changes in the Company’s use of valuation techniques since December 31, 2018. The Company reviews fair value prices provided by its outside investment accounting service provider or investment managers for reasonableness by comparing the fair values provided by the managers to those provided by its investment custodian. The Company also reviews and monitors changes in unrealized gains and losses. The Company has not historically adjusted security prices. The Company obtains an understanding of the methods, models and inputs used by the investment managers and independent pricing services, and controls are in place to validate that prices provided represent fair values. The Company’s control process includes, but is not limited to, initial and ongoing evaluation of the methodologies used, a review of specific securities and an assessment for proper classification within the fair value hierarchy, and obtaining and reviewing internal control reports for our investment manager that obtains fair values from independent pricing services. Assets measured at fair value on a recurring basis as of December 31, 2020 are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ — $ 296,405 $ — $ 296,405 Residential mortgage-backed — 293,848 — 293,848 Corporate — 766,822 — 766,822 Commercial mortgage and asset-backed — 326,719 326,719 U.S. Treasury securities and obligations guaranteed by the U.S. government 99,384 464 — 99,848 Total fixed maturity securities, available-for-sale $ 99,384 $ 1,684,258 $ — $ 1,783,642 Equity securities: Preferred stock $ — $ 67,495 $ — $ 67,495 Common stock 15,793 5,015 672 21,480 Total equity securities $ 15,793 $ 72,510 $ 672 $ 88,975 Bank loan participations $ — $ 147,296 $ 308 $ 147,604 Short-term investments $ — $ 130,289 $ — $ 130,289 Assets measured at fair value on a recurring basis as of December 31, 2019 are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ — $ 167,101 $ — $ 167,101 Residential mortgage-backed — 264,146 — 264,146 Corporate — 632,221 — 632,221 Commercial mortgage and asset-backed — 252,457 — 252,457 U.S. Treasury securities and obligations guaranteed by the U.S. government 115,173 494 — 115,667 Redeemable preferred stock — 2,034 — 2,034 Total fixed maturity securities, available-for-sale $ 115,173 $ 1,318,453 $ — $ 1,433,626 Equity securities: Preferred stock $ — $ 62,747 $ — $ 62,747 Common stock 14,669 3,276 43 17,988 Total equity securities $ 14,669 $ 66,023 $ 43 $ 80,735 Short-term investments $ — $ 156,925 $ — $ 156,925 A reconciliation of the beginning and ending balances of available-for-sale fixed maturity securities, equity securities, and bank loan participations (following the Company's election of the fair value option in accounting for bank loan participations effective January 1, 2020) measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is shown below: Year Ended December 31, 2020 2019 2018 (in thousands) Beginning balance $ 43 $ 4,442 $ 4,680 Transfers in to Level 3 358 3,010 — Transfers out of Level 3 (767) (7,238) — Purchases 1,417 214 Sales — — — Maturities and calls (17) (452) Amortization of discount 2 — — Total gains or losses (realized/unrealized): Included in earnings (56) (171) — Included in other comprehensive income — — — Ending balance $ 980 $ 43 $ 4,442 The Company held one available-for-sale fixed maturity security and one equity security at December 31, 2018 for which the fair value was determined using significant unobservable inputs (Level 3). A market approach using prices in trades of comparable securities was utilized to determine a fair value of $4.4 million for the securities at December 31, 2018. During 2019, the Company was able to obtain a quoted price from a pricing vendor for the available-for-sale fixed maturity security, and the security was transferred to Level 2. The Company held one equity security at December 31, 2019 for which the fair value was determined using significant unobservable inputs (Level 3). A market approach using prices in trades of comparable securities was utilized to determine a fair value for the equity security of $43,000 at December 31, 2019. During 2019, one equity security was transferred from Level 1 to Level 3 as the security was no longer actively traded. The Company was subsequently able to obtain a quoted price from a pricing vendor for the equity security and it was transferred from Level 3 to Level 2. At December 31, 2020, the Company held one bank loan participation and two equity securities for which the fair value was determined using significant unobservable inputs (Level 3). A market approach using prices in trades of comparable securities was utilized to determine a fair value of $980,000. During 2020, the Company was able to obtain a quoted price from a vendor for two bank loan participations and one equity security and transferred them to Level 2. Transfers out of Level 3 occur when the Company is able to obtain reliable prices from pricing vendors for which the Company was previously unable to obtain reliable prices. Transfers in to Level 3 occur when the Company is unable to obtain reliable prices for securities from pricing vendors and instead must use broker price quotes. There were no transfers between Level 1 and Level 2 during 2020, 2019 or 2018. The Company recognizes transfers between levels at the beginning of the reporting period. In connection with the adoption of ASU 2016-13, the Company elected the fair value option in accounting for bank loan participations effective January 1, 2020. Prior to the election, bank loan participations were classified as held-for-investment and carried at amortized cost net of any allowance for credit losses. Prior to January 1, 2020, the Company measured certain bank loan participations at fair value on a non-recurring basis as part of the Company's impairment evaluation when loans were determined by management to be impaired. Bank loan participations held-for-investment that were determined to be impaired were written down to their fair value at December 31, 2019 as shown below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) December 31, 2019 Bank loan participations held-for-investment $ — $ — $ 6,949 $ 6,949 In the determination of the fair value for bank loan participations and certain high yield bonds, the Company’s investment manager endeavors to obtain data from multiple external pricing sources. External pricing sources may include brokers, dealers and price data vendors that provide a composite price based on prices from multiple dealers. Such external pricing sources typically provide valuations for normal institutional size trading units of such securities using methods based on market transactions for comparable securities, and various relationships between securities, as generally recognized by institutional dealers. For investments in which the investment manager determines that only one external pricing source is appropriate or if only one external price is available, the relevant investment is generally recorded at fair value based on such price. Investments for which external sources are not available or are determined by the investment manager not to be representative of fair value are recorded at fair value as determined by the Company, with input from its investment managers and valuation specialists as considered necessary. In determining the fair value of such investments, the Company considers one or more of the following factors: type of security held, convertibility or exchangeability of the security, redeemability of the security (including the timing of redemptions), application of industry accepted valuation models, recent trading activity, liquidity, estimates of liquidation value, purchase cost, and prices received for securities with similar terms of the same issuer or similar issuers. There were no investments for which external sources were unavailable to determine fair value as of December 31, 2020 and 2019. The carrying values and fair values of financial instruments are summarized below: December 31, 2020 2019 Carrying Fair Carrying Fair (in thousands) Assets Fixed maturity securities, available-for-sale $ 1,783,642 $ 1,783,642 $ 1,433,626 $ 1,433,626 Equity securities 88,975 88,975 80,735 80,735 Bank loan participations 147,604 147,604 260,864 252,423 Cash and cash equivalents 162,260 162,260 206,912 206,912 Restricted cash equivalents 859,920 859,920 1,199,164 1,199,164 Short-term investments 130,289 130,289 156,925 156,925 Other invested assets – notes receivable 4,500 5,302 13,250 18,756 Liabilities Senior debt 262,300 250,953 158,300 158,043 Junior subordinated debt 104,055 110,612 104,055 122,193 The fair values of fixed maturity securities, equity securities, and bank loan participations have been determined using quoted market prices for securities traded in the public market or prices using bid or closing prices for securities not traded in the public marketplace. The fair values of cash and cash equivalents and short-term investments approximate their carrying values due to their short-term maturity. The fair values of other invested assets-notes receivable, senior debt, and junior subordinated debt at December 31, 2020 and 2019 were determined by calculating the present value of expected future cash flows under the terms of the note agreements or debt agreements, as applicable, discounted at an estimated market rate of interest at December 31, 2020 and 2019, respectively. The fair values of senior debt and junior subordinated debt at December 31, 2020 and 2019 were determined using inputs to the valuation methodology that are unobservable (Level 3).

Statutory Matters

Statutory Matters	12 Months Ended
	Dec. 31, 2020
Statutory Matters [Abstract]
Statutory Matters	Statutory Matters U.S. U.S. state insurance laws and regulations prescribe accounting practices for determining statutory net income and capital and surplus for insurance companies. In addition, state regulators may permit statutory accounting practices that differ from prescribed practices. Statutory accounting practices prescribed or permitted by regulatory authorities for the Company’s insurance subsidiaries differ from U.S. GAAP. The principal differences between SAP and GAAP as they relate to the financial statements of the Company’s insurance subsidiaries are (a) policy acquisition costs are expensed as incurred under SAP, whereas they are deferred and amortized under GAAP, (b) certain assets are not admitted for purposes of determining surplus under SAP, (c) the classification and carrying amounts of investments in certain securities are different under SAP and GAAP, and (d) the criteria for providing asset valuation allowances and the methodologies used to determine the amount thereof are different under SAP and GAAP. Combined net income, statutory capital and surplus and minimum required statutory capital and surplus, as determined in accordance with statutory accounting practices, for the U.S. insurance subsidiaries as of December 31, 2020, 2019, and 2018 and for the years then ended are summarized as follows: 2020 2019 2018 (in thousands) Statutory net (loss) income $ (710) $ 3,586 $ 6,770 Statutory capital and surplus 286,449 266,715 241,668 Minimum required statutory capital and surplus 100,170 111,208 24,850 Risk-Based Capital (“RBC”) requirements promulgated by the National Association of Insurance Commissioners require property-casualty insurers to maintain minimum capitalization levels determined based on formulas incorporating various business risks of the insurance subsidiaries. As of December 31, 2020, the insurance subsidiaries’ adjusted capital and surplus exceeds their authorized control level RBC. Bermuda The Company has two Bermuda-based insurance subsidiaries: JRG Re, a Class 3B insurer and Carolina Re, a Class 3A insurer. Under the Bermuda Insurance Act 1978 and related regulations, an insurer must maintain minimum statutory capital and surplus at the greater of a minimum solvency margin (“MSM”) and the Enhanced Capital Requirement (“ECR”), which is the higher of the MSM and capital calculated by the Bermuda Solvency Capital Requirement (“BSCR”) model or an approved internal model. The combined estimated Bermuda insurers minimum statutory solvency margin required at December 31, 2020 was approximately $172.9 million (2019: $161.4 million). Actual combined statutory capital and surplus at December 31, 2020 was $615.2 million (2019: $502.6 million). The insurers had combined statutory net income of $20.8 million for 2020, $53.2 million for 2019, and $86.5 million for 2018. The combined ECR for the year ended December 31, 2019 was $377.3 million. The BSCR models for the year ended December 31, 2020 will not be filed with the Bermuda Monetary Authority until April 30, 2021. The Company believes that the minimum statutory capital and surplus requirements will be met. The insurers must also maintain a minimum liquidity ratio in which the value of its relevant assets is not less than 75.0% of the amount of its relevant liabilities for general business. Relevant assets include cash and cash equivalents, fixed maturities, quoted alternative investments, accrued interest income, premiums receivable, losses recoverable from reinsurers, and funds withheld. The relevant liabilities include total insurance provisions and other liabilities less deferred income taxes and letters of credit, guarantees and other instruments. As of December 31, 2020 the minimum liquidity ratio requirements were met.

Dividend Restrictions

Dividend Restrictions	12 Months Ended
	Dec. 31, 2020
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments [Abstract]
Dividend Restrictions	Dividend Restrictions U.S. The insurance statutes of the U.S.-based insurance subsidiaries’ states of domicile limit the amount of dividends that they may pay annually without first obtaining regulatory approval. Generally, the limitations are based on the greater of statutory net income for the preceding year or 10.0% of statutory surplus at the end of the preceding year. The maximum amount of dividends available to James River Group from its U.S. insurance subsidiaries during 2021 without regulatory approval is $28.6 million. However, U.S. insurance regulators have broad powers to prevent the reduction of statutory surplus to inadequate levels and could refuse to permit the payment of dividends. Distributions from the Company’s U.S.-based subsidiaries to its U.K. intermediate holding company, James River UK, are generally subject to a 5% dividend withholding tax. The payment of any dividends by the Company’s U.S.-based subsidiaries directly to a Bermuda-based entity is subject to U.S. taxes at a 30.0% tax rate. JRG Holdings has determined that earnings of its U.S. subsidiaries have been and will be indefinitely reinvested in U.S. operations. Bermuda The Bermuda Insurance Act of 1978 prohibits an insurer from declaring or paying a dividend if it is in breach of its minimum solvency margin, its enhanced capital requirement, or its minimum liquidity ratio, or if the declaration or payment of such dividend would cause such a breach. An insurer can declare or pay dividends without prior regulatory approval up to 25% of the total statutory capital and surplus (as shown on its previous financial year's statutory balance sheet). The maximum combined amount of dividends and return of capital that can be paid without prior regulatory approval from our Bermuda insurers at December 31, 2020 is calculated to be approximately $153.8 million. However, this dividend amount is subject to annual enhanced solvency requirement calculations. As of December 31, 2020, JRG Holdings had consolidated retained earnings of $49.2 million, all of which was available for the payment of dividends to shareholders.

Other Related Party Transaction

Other Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Other Related Party Transactions	Other Related Party Transactions The Company leases a commercial office building which houses the Company’s Richmond, Virginia operations under the terms of a non-cancelable lease from an entity with which it is affiliated. The term of the lease, which has been amended from time to time, runs through 2026. Operating costs under the lease were $1.9 million, $2.1 million, and $2.6 million for the years ended December 31, 2020, 2019, and 2018, respectively. The Chief Executive Officer of the Company previously owned a plane that the Company periodically leased. Total fees paid by the Company for the use of this plane were $123,000 in 2018 (none in 2019 or 2020).

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On February 17, 2021, the Board of Directors declared a cash dividend of $0.30 per share. The dividend is payable on March 31, 2021 to shareholders of record on March 15, 2021. On February 17, 2021, the Board of Directors granted awards under the 2014 LTIP and the 2014 Director Plan to the Company’s employees and directors. RSUs for 138,936 shares were awarded with a fair value on the date of grant of $50.24 per share. The RSUs vest over one three On January 14, 2021, the Company's Corporate and Other and Excess and Surplus Lines segments invested $5.0 million and $4.0 million, respectively, in notes receivable for renewable energy projects. The notes, issued by an entity for which two of our recent former directors serve as officers, pay interest at 12% per annum and mature in 2025 .

SCHEDULE I - Summary of Investm

SCHEDULE I - Summary of Investments - Other than Investments in Related Parties	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract]
Summary of Investments - Other than Investments in Related Parties	Summary of Investments—Other than Investments in Related Parties Type of Investment Cost or Fair Amount at which shown on Balance Sheet (1) (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ 277,241 $ 296,405 $ 296,405 Residential mortgage-backed 286,104 293,848 293,848 Corporate 715,145 766,822 766,822 Commercial mortgage and asset-backed 314,911 326,719 326,719 U.S. Treasury securities and obligations guaranteed by the U.S. government 97,489 99,848 99,848 Total fixed maturity securities, available-for-sale 1,690,890 1,783,642 1,783,642 Equity securities: Preferred Stock 54,228 67,495 67,495 Common Stock 27,470 21,480 21,480 Total equity securities 81,698 88,975 88,975 Bank loan participations 154,728 147,604 147,604 Short-term investments 130,289 130,289 130,289 Other invested assets 11,903 Total invested assets $ 2,162,413 (1) Differences between the amounts in this column and the amounts in the consolidated balance sheet are due to this schedule excluding investments in related parties.

SCHEDULE II - Condensed Financi

SCHEDULE II - Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
Statements of financial information of parent company only (Parent Company)	Condensed Financial Information of Registrant Balance Sheets (Parent Company) December 31, 2020 2019 (in thousands) Assets Cash and cash equivalents $ 571 $ 1,521 Investment in subsidiaries 1,145,887 987,221 Due from subsidiaries 1,140 7,371 Other assets 3,116 2,842 Total assets $ 1,150,714 $ 998,955 Liabilities and shareholders’ equity Liabilities: Accrued expenses $ 1,824 $ 1,592 Senior debt 247,300 143,300 Junior subordinated debt 15,928 15,928 Notes payable to subsidiary 70,000 40,000 Due to subsidiaries 19,391 18,822 Other liabilities 663 732 Total liabilities 355,106 220,374 Commitments and contingent liabilities Shareholders’ equity: Class A common shares 6 6 Additional paid-in capital 664,476 657,875 Retained earnings 49,227 89,586 Accumulated other comprehensive income 81,899 31,114 Total shareholders’ equity 795,608 778,581 Total liabilities and shareholders’ equity $ 1,150,714 $ 998,955 See accompanying notes. SCHEDULE II JAMES RIVER GROUP HOLDINGS, LTD. AND SUBSIDIARIES Condensed Financial Information of Registrant Statements of Income and Comprehensive Income (Parent Company) Year Ended December 31, 2020 2019 2018 (in thousands) Revenues: Other income $ 45 $ 61 $ 58 Total revenues 45 61 58 Expenses: Other operating expenses 14,960 14,267 13,768 Other expenses — — 337 Interest expense 6,234 5,047 5,122 Total expenses 21,194 19,314 19,227 Loss before equity in net income of subsidiaries (21,149) (19,253) (19,169) Equity in net income of subsidiaries 25,973 57,592 82,999 Net income $ 4,824 $ 38,339 $ 63,830 Other comprehensive income (loss): Equity in other comprehensive earnings (losses) of subsidiaries 50,785 46,942 (22,203) Total comprehensive income $ 55,609 $ 85,281 $ 41,627 See accompanying notes. SCHEDULE II JAMES RIVER GROUP HOLDINGS, LTD. AND SUBSIDIARIES Condensed Financial Information of Registrant Statements of Cash Flows (Parent Company) Year Ended December 31, 2020 2019 2018 (in thousands) Operating activities Net income $ 4,824 $ 38,339 $ 63,830 Adjustments to reconcile net income to net cash (used in) provided by operating activities: Provision for depreciation and amortization 216 182 176 Share based compensation expense 7,625 7,178 6,228 Equity in undistributed earnings of subsidiaries (25,973) (49,592) 6,000 Changes in operating assets and liabilities 6,433 (2,782) (5,653) Net cash (used in) provided by operating activities (6,875) (6,675) 70,581 Investing activities Net cash provided by investing activities — — — Financing activities Dividends paid (37,051) (36,720) (36,123) Senior debt issuance 164,000 60,000 20,000 Senior debt repayments (60,000) (20,000) — Subsidiary note issuance 30,000 — — Subsidiary note repayments — — (60,000) Contribution to subsidiary (90,000) — — Debt issue costs paid — (711) — Issuances of common shares under equity incentive plans 2,580 8,286 5,172 Common share repurchases (3,604) (2,899) (2,239) Net cash provided by (used in) financing activities 5,925 7,956 (73,190) Change in cash and cash equivalents (950) 1,281 (2,609) Cash and cash equivalents at beginning of period 1,521 240 2,849 Cash and cash equivalents at end of period $ 571 $ 1,521 $ 240 Supplemental information Interest paid $ 6,530 $ 5,710 $ 5,052 See accompanying notes. SCHEDULE II JAMES RIVER GROUP HOLDINGS, LTD. AND SUBSIDIARIES Condensed Financial Information of Registrant Notes to Condensed Financial Statements 1. Accounting Policies Organization James River Group Holdings, Ltd. (the “Company”) is an exempted holding company registered in Bermuda, organized for the purpose of acquiring and managing insurance and reinsurance entities. Basis of Presentation The accompanying condensed financial statements have been prepared using the equity method. Under the equity method, the investment in consolidated subsidiaries is stated at cost plus equity in undistributed earnings of consolidated subsidiaries since the date of acquisition. These condensed financial statements should be read in conjunction with the Company’s consolidated financial statements. Estimates and Assumptions Preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying disclosures. Those estimates are inherently subject to change, and actual results may ultimately differ from those estimates. Adopted Accounting Standards On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , using the modified retrospective approach, by which a cumulative-effect adjustment was made to retained earnings as of the date of adoption. This update requires financial assets measured at amortized cost, such as bank loan participations held for investment, to be presented at the net amount expected to be collected by means of an allowance for credit losses that is reflected in net income. Credit losses relating to available-for-sale debt securities are recorded through an allowance for credit losses, with the amount of the allowance limited to the amount by which fair value is below amortized cost. In connection with the adoption of this ASU, the Company elected the fair value option in accounting for bank loan participations effective January 1, 2020. The targeted transition relief offered by ASU 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief was applied to elect the fair value option to account for bank loan participations already held at the January 1, 2020 date of adoption. Under the fair value option, bank loan participations are measured at fair value, and changes in unrealized gains and losses in bank loan participations are reported in our income statement as net realized and unrealized gains (losses) on investments. At adoption on January 1, 2020, the Company reduced the carrying value of its bank loan portfolio to fair value through an $8.4 million adjustment with a $7.8 million (net of tax) cumulative effect adjustment to reduce retained earnings. Upon adoption of this ASU, the Company established an allowance for credit losses on reinsurance balances through a $265,000 (net of tax) cumulative effect adjustment to retained earnings. Because we purchase reinsurance from financially strong reinsurers or we have collateral securing the recoverables, the effect of adoption was not material to our financial position.

SCHEDULE III - Supplementary In

SCHEDULE III - Supplementary Insurance Information	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Abstract]
Supplementary Insurance Information	Supplementary Insurance Information (in thousands) Deferred Reserve Unearned Net Net Losses Amortization Other Net December 31, 2020 Excess and Surplus Lines $ 25,875 $ 1,276,054 $ 345,976 $ 415,168 $ 18,664 $ 318,467 $ 49,387 $ 88,520 $ 450,346 Specialty Admitted (3,073) 600,309 136,355 57,505 3,392 41,928 (4,525) 13,213 59,884 Casualty Reinsurance 40,151 315,717 148,040 134,133 42,554 118,150 30,716 34,347 137,544 Corporate and Other — — — — 8,758 — — 29,418 — Total $ 62,953 $ 2,192,080 $ 630,371 $ 606,806 $ 73,368 $ 478,545 $ 75,578 $ 165,498 $ 647,774 December 31, 2019 Excess and Surplus Lines $ 24,428 $ 1,245,581 $ 267,924 $ 625,528 $ 21,358 $ 528,133 $ 49,720 $ 87,326 $ 685,814 Specialty Admitted (2,902) 511,027 115,606 54,338 3,802 34,860 (3,560) 13,986 58,637 Casualty Reinsurance 40,480 288,898 140,847 143,880 46,325 109,109 37,733 41,932 151,699 Corporate and Other — — — — 4,167 — — 27,664 — Total $ 62,006 $ 2,045,506 $ 524,377 $ 823,746 $ 75,652 $ 672,102 $ 83,893 $ 170,908 $ 896,150 December 31, 2018 Excess and Surplus Lines $ 16,736 $ 960,562 $ 175,231 $ 555,684 $ 14,456 $ 437,904 $ 48,299 $ 88,865 $ 571,098 Specialty Admitted (1,829) 426,315 84,659 55,146 3,262 32,623 (1,792) 15,551 55,840 Casualty Reinsurance 39,543 274,582 126,583 204,568 38,838 129,749 64,596 69,716 135,734 Corporate and Other — — — — 4,700 — — 26,903 — Total $ 54,450 $ 1,661,459 $ 386,473 $ 815,398 $ 61,256 $ 600,276 $ 111,103 $ 201,035 $ 762,672

SCHEDULE IV - Reinsurance

SCHEDULE IV - Reinsurance	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
Reinsurance	Reinsurance Direct Ceded Assumed Net Percentage (in thousands) Year Ended December 31, 2020 Excess and Surplus Lines Written Premiums $ 699,143 $ 248,797 $ — $ 450,346 — Specialty Admitted Written Premiums 404,851 348,807 3,840 59,884 6.4 % Casualty Reinsurance Written Premiums — 11,622 149,166 137,544 108.4 % Total Written Premiums $ 1,103,994 $ 609,226 $ 153,006 $ 647,774 23.6 % Year Ended December 31, 2019 Excess and Surplus Lines Written Premiums $ 922,320 $ 236,506 $ — $ 685,814 — Specialty Admitted Written Premiums 383,628 329,005 4,014 58,637 6.8 % Casualty Reinsurance Written Premiums — 9,074 160,773 151,699 106.0 % Total Written Premiums $ 1,305,948 $ 574,585 $ 164,787 $ 896,150 18.4 % Year Ended December 31, 2018 Excess and Surplus Lines Written Premiums $ 656,538 $ 85,440 $ — $ 571,098 — Specialty Admitted Written Premiums 370,684 318,506 3,662 55,840 6.6 % Casualty Reinsurance Written Premiums — 155 135,889 135,734 100.1 % Total Written Premiums $ 1,027,222 $ 404,101 $ 139,551 $ 762,672 18.3 %

SCHEDULE V - Valuation and Qual

SCHEDULE V - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	Valuation and Qualifying Accounts Balance Additions Amounts Charged to Expense Deductions Amounts Written Off or Disposals Balance (in thousands) Year Ended December 31, 2020 Allowance for Credit Losses on Premiums Receivable and Agents' Balances $ 5,659 $ 3,318 $ (660) $ 8,317 Allowance for Credit Losses on Bank Loans 7,181 — (7,181) — Total $ 12,840 $ 3,318 $ (7,841) $ 8,317 Year Ended December 31, 2019 Allowance for Credit Losses on Premiums Receivable and Agents' Balances $ 3,948 $ 2,523 $ (812) $ 5,659 Allowance for Credit Losses on Bank Loans — 8,898 (1,717) 7,181 Total $ 3,948 $ 11,421 $ (2,529) $ 12,840 Year Ended December 31, 2018 Allowance for Credit Losses on Premiums Receivable and Agents' Balances $ 2,757 $ 1,504 $ (313) $ 3,948 Allowance for Credit Losses on Bank Loans 3,219 950 (4,169) — Total $ 5,976 $ 2,454 $ (4,482) $ 3,948 In connection with the adoption of ASU 2016-13, the Company elected the fair value option in accounting for bank loan participations effective January 1, 2020. Under the fair value option, bank loan participations are measured at fair value, and changes in unrealized gains and losses in bank loan participations are reported in our income statement as net realized and unrealized gains (losses) on investments.

SCHEDULE VI - Supplementary Inf

SCHEDULE VI - Supplementary Information Concerning Property Casualty Insurance Operations	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]
Supplementary Information Concerning Property Casualty Insurance Operations	Supplementary Information Concerning Property Casualty Insurance Operations Year Ended December 31, 2020 2019 2018 (in thousands) Deferred policy acquisition costs $ 62,953 $ 62,006 $ 54,450 Reserve for losses and loss adjustment expenses 2,192,080 2,045,506 1,661,459 Unearned premiums 630,371 524,377 386,473 Net earned premiums 606,806 823,746 815,398 Net investment income 73,368 75,652 61,256 Losses and loss adjustment expenses incurred: Current year 386,341 603,094 582,604 Prior year 92,204 69,008 17,672 Total losses and loss adjustment expenses incurred 478,545 672,102 600,276 Amortization of policy acquisition costs 75,578 83,893 111,103 Paid losses and loss adjustment expenses, net of reinsurance 469,945 488,729 396,013 Net written premiums 647,774 896,150 762,672

Accounting Policies (Policies)

Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”), which vary in some respects from statutory accounting practices (“SAP”) which are prescribed or permitted by the various state insurance departments in the U.S. or by insurance regulators in Bermuda. The accompanying consolidated financial statements include the accounts and operations of the Company and its subsidiaries. Intercompany transactions and balances have been eliminated.
Estimates and Assumptions	Estimates and Assumptions Preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying disclosures. Those estimates are inherently subject to change, and actual results may ultimately differ from those estimates.
Fixed Maturity and Equity Securities	Fixed Maturity and Equity Securities Fixed maturity securities classified as “available-for-sale” are carried at fair value, and unrealized gains and losses on such securities, net of any deferred taxes, are reported as a separate component of accumulated other comprehensive income. The Company does not have any securities classified as “held-to-maturity” or “trading”. Fair value generally represents quoted market value prices for securities traded in the public marketplace or prices analytically determined using bid or closing prices for securities not traded in the public marketplace. Premiums and discounts on mortgage-backed securities and asset-backed securities are amortized or accrued using the constant yield method which considers anticipated prepayments at the date of purchase. To the extent that the estimated lives of such securities change as a result of changes in estimated prepayment rates, the adjustments are included in net investment income using the retrospective method. Realized investment gains or losses are determined on a specific identification basis. Interest income is recognized as earned, and dividend income is recognized on the ex-dividend date. The Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments on January 1, 2020. This update changed the impairment model for available-for-sale fixed maturities and requires the Company to determine whether unrealized losses on available-for-sale fixed maturities are due to credit-related factors. An allowance for credit losses is established for any credit-related impairments, limited to the amount by which fair value is below amortized cost. Changes in the allowance for credit losses are recognized in earnings and included in n et realized and unrealized gains (losses) on investments . Unrealized losses that are not credit-related will continue to be recognized in other comprehensive income. The Company considers the extent to which fair value is below amortized cost in determining whether a credit-related loss exists. The Company also considers the credit quality rating of the security, with a special emphasis on securities downgraded below investment grade. A comparison is made between the present value of expected future cash flows for a security and its amortized cost. If the present value of future expected cash flows is less than amortized cost, a credit loss is presumed to exist and an allowance for credit losses is established. Management may conclude that a qualitative analysis is sufficient to support its conclusion that the present value of the expected cash flows equals or exceeds a security’s amortized cost. Effective January 1, 2018, with the adoption of ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities , equity securities (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) are measured at fair value with changes in fair value recognized in net realized and unrealized gains or losses. Prior to the adoption of ASU 2016-01, changes in the fair value of equity securities were recognized net of taxes as a component of accumulated other comprehensive income.
Bank Loan Participations	Bank Loan Participations Bank loan participations are managed by a specialized outside investment manager. In connection with the adoption of ASU 2016-13, the Company elected the fair value option in accounting for bank loan participations effective January 1, 2020. Under the fair value option, bank loan participations are measured at fair value, and changes in unrealized gains and losses in bank loan participations are reported in our income statement as net realized and unrealized gains (losses) on investments. Losses due to credit-related impairments on bank loan participations are determined based upon consultations and advice from the Company's specialized investment manager and consideration of any adverse situations that could affect the borrower's ability to repay, the estimated value of underlying collateral, and other relevant factors. Interest income is accrued on the unpaid principal balance. Discounts and premiums are amortized to income using the interest method. Prior to the election of the fair value option on January 1, 2020, bank loan participations were generally stated at their outstanding unpaid principal balances net of unamortized premiums or discounts and net of any allowance for credit losses. The allowance for credit losses was maintained at a level considered adequate to absorb estimated probable credit losses. Generally, the accrual of interest on a bank loan participation is discontinued when the contractual payment of principal or interest has become 90 days past due or management has serious doubts about further collectability of principal or interest. A bank loan participation may remain on accrual status if it is in the process of collection and is either guaranteed or well secured. Interest received on nonaccrual loans generally is reported as investment income. There were no bank loans on nonaccrual status at December 31, 2020 or 2019. Generally, bank loan participations are restored to accrual status when the obligation is brought current, has performed in accordance with the contractual terms for a reasonable period of time, and the ultimate collectability of the total contractual principal and interest is no longer in doubt.
Other Invested Assets	Other Invested Assets Other invested assets at December 31, 2020 and 2019 include the Company’s interests in private debt and equity investments. The investments are primarily focused in renewable energy, limited partnerships, and bank holding companies. Equity interests in various limited liability companies (“LLCs”) and limited partnerships are accounted for under the equity method, as the Company has determined that the equity method best reflects its economic interest in the underlying equity investment.
Short-Term Investments	Short-Term Investments Short-term investments are carried at amortized cost, which approximates fair value. Short-term investments have maturities greater than three months but less than one year at the date of purchase.
Cash Equivalents and Restricted Cash Equivalents	Cash Equivalents The Company considers highly liquid investments with maturities of three months or less at the date of purchase to be cash equivalents. Restricted Cash Equivalents
Direct Written Premiums	Direct Written Premiums Direct written premiums are earned on a pro rata basis over the terms of the policies, generally 12 months. The portion of premiums written applicable to the unexpired terms of the policies in force is recorded as unearned premiums. Policies are accounted for on an individual basis, with no aggregation by counterparty.
Assumed Reinsurance Premiums	Assumed Reinsurance Premiums Assumed reinsurance written premiums include amounts reported by brokers and ceding companies, supplemented by the Company’s own estimates of premiums when reports have not been received. Premiums on the Company’s excess of loss and pro rata reinsurance contracts are estimated when the business is underwritten. For excess of loss contracts, the deposit premium, as defined in the contract, is generally recorded as an estimate of premiums written at the inception date of the treaty. Estimates of premiums written under pro rata contracts are recorded in the period in which the underlying risks are expected to begin and are based on information provided by the brokers and the ceding companies. Reinsurance premium estimates are reviewed by management periodically. Any adjustment to these estimates is recorded in the period in which it becomes known. Reinsurance premiums assumed are earned over the terms of the underlying policies or reinsurance contracts. Contracts and policies written on a “losses occurring” basis cover claims that may occur during the term of the contract or policy, which is typically 12 months. Accordingly, the premium is earned evenly over the term. Contracts which are written on a “risks attaching” basis cover claims which attach to the underlying insurance policies written during the terms of such contracts. Premiums earned on such contracts usually extend beyond the original term of the reinsurance contract, typically resulting in recognition of premiums earned over a 24-month period in proportion to the level of underlying exposure. Contracts are accounted for on an individual basis, with no aggregation by counterparty.
Premiums Receivable and Agents' Balances, Net	Premiums Receivable and Agents’ Balances, Net Premiums receivable and agents’ balances are carried at face value net of any allowance for credit losses. The allowance for credit losses represents the current estimate of expected credit losses based on the Company’s assessment of the collectability of receivables that are past due, historical collection percentages, and consideration of current economic conditions and expectations of future conditions that could affect ultimate collections. Receivables greater than 90 days past due were $6.9 million and $3.3 million at December 31, 2020 and 2019, respectively. The allowance for credit losses was $8.3 million and $5.7 million at December 31, 2020 and 2019, respectively. Bad debt expense was $3.3 million for the year ended December 31, 2020, $2.5 million for the year ended December 31, 2019, and $1.5 million for the year ended December 31, 2018. Receivables written off against the allowance for credit losses totaled $660,000 for the year ended December 31, 2020, $812,000 for the year ended December 31, 2019, and $313,000 for the year ended December 31, 2018. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote.
Deferred Policy Acquisition Costs	Deferred Policy Acquisition Costs Costs which are incrementally or directly related to the successful acquisition of new or renewal insurance business are deferred. These deferred costs are primarily commissions to agents, ceding commissions paid on reinsurance assumed, premium taxes, and the portion of underwriting fixed compensation and payroll related fringe benefits directly related to an insurance contract that has been acquired, net of ceding commissions related to reinsurance ceded. Amortization of such policy acquisition costs is charged to expense in proportion to premium earned over the estimated policy life. To the extent that
Reinsurance and Adjustable Features of Insurance and Reinsurance Contracts	Reinsurance and Adjustable Features of Insurance and Reinsurance Contracts Certain premiums and losses are ceded to other insurance companies or assumed from other insurance companies under various excess of loss and quota-share reinsurance contracts. The Company enters into ceded reinsurance contracts to limit its exposure to large losses, to limit exposure on new lines of insurance written by the Company, and to provide additional capacity for growth. Premiums, commissions, and losses and loss adjustment expenses on reinsured business are accounted for on a basis consistent with that used in accounting for the original policies issued and the terms of the reinsurance contracts. Reinsurance recoverables and prepaid reinsurance premiums are reported as assets. The Company uses a provision matrix to calculate the allowance for credit losses on reinsurance recoverables by applying impairment rates based on historical loss data to similarly rated reinsurance companies based on the expected duration of the receivables. The Company also considers the expected impact of current and future expected economic conditions and adjusts estimates if needed based on an evaluation of these factors. The allowance for credit losses on reinsurance recoverables at December 31, 2020 was $335,000. Other amounts payable to insurance companies and reinsurers or receivable from insurance companies and reinsurers are netted where the right of offset exists. The Company receives ceding commissions in connection with certain ceded reinsurance. The ceding commissions are recorded as a reduction of other operating expenses. Certain reinsurance contracts include provisions that adjust premiums or acquisition expenses based upon the loss experience under the contracts. Premiums written and earned, as well as related acquisition expenses are recorded based upon the projected loss experience under the contracts. The Company’s Specialty Admitted Insurance segment writes insurance under specialty admitted fronting and program arrangements. The fronting and program arrangements may contain contractual provisions that adjust acquisition expenses based upon loss experience under the contracts. The specialty admitted fronting and program arrangements are significantly reinsured. These reinsurance contracts may also contain provisions that adjust premiums or acquisition expenses based upon the loss experience under the contracts. Premiums written and earned, as well as related acquisition expenses, are recorded based upon the projected loss experience under the contracts.
Other Income	Other Income Other income is principally comprised of fee income earned on policies for which the Company has no exposure to underwriting risk. Fee income of $3.4 million, $9.5 million, and $13.9 million is included in other income for the years ended December 31, 2020, 2019, and 2018, respectively. Fees are earned on a pro rata basis over the service period of the underlying business. Policies are accounted for on an individual basis, with no aggregation by counterparty.
Income Taxes	Income Taxes Deferred tax assets and deferred tax liabilities are provided for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of assets and liabilities and their respective U.S. tax basis. Deferred tax assets and liabilities are measured using enacted U.S. corporate tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax assets are reduced by a valuation allowance only when management believes it is more likely than not that some, or all, of the deferred tax assets will not be realized. Effective January 1, 2018, the Company adopted ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.
Goodwill	Goodwill Goodwill is tested annually for impairment in the fourth quarter of each calendar year, or more frequently if events or changes in circumstances indicate that the carrying amount of the Company’s reporting units, including goodwill, may exceed
Intangible Assets, Net	Intangible Assets, Net Intangible assets are initially recognized and measured at fair value. Specifically identified intangible assets with indefinite lives include trademarks and state insurance licenses and authorities. Other specifically identified intangible assets with lives ranging from 7.0 to 27.5 years represent relationships with brokers. These intangible assets are amortized on a straight-line basis over their estimated useful lives. Intangible assets with indefinite useful lives are reviewed for impairment at least annually. In evaluating whether there has been impairment to the intangible asset, management determines the fair value of the intangible asset and compares the resulting fair value to the carrying value of the intangible asset. If the carrying value exceeds the fair value, the intangible asset is written down to fair value, and the impairment is reported through earnings. The Company evaluates intangible assets with definite lives for impairment when impairment indicators are noted.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets with finite lives are tested for impairment whenever recognized events or changes in circumstances indicate the carrying value of these assets may not be recoverable. If indicators of impairment are present, fair value is calculated using estimated future cash flows expected to be generated from the use of those assets. An impairment loss is recognized only if the carrying amount of a long-lived asset or asset group is not recoverable and exceeds its fair value. The carrying amount of a long-lived asset or asset group is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset or asset group. That assessment is based on the carrying amount of the asset or asset group at the date it is tested for recoverability. An impairment loss is measured as the amount by which the carrying amount of a long-lived asset or asset group exceeds its fair value.
Property and Equipment, Net	Property and Equipment, Net Property and equipment, which is included in “other assets” in the accompanying consolidated balance sheets, is reported at cost less accumulated depreciation and is depreciated principally on a straight-line basis over the estimated useful lives of the depreciable assets, generally three
Reserve for Losses and Loss Adjustment Expenses	Reserve for Losses and Loss Adjustment Expenses The reserve for losses and loss adjustment expenses represents the estimated ultimate cost of all reported and unreported losses and loss adjustment expenses incurred and unpaid at the balance sheet date. The Company does not discount this reserve. The process of estimating the reserve for losses and loss adjustment expenses requires a high degree of judgment and is subject to a number of variables. The reserve for losses and loss adjustment expenses is estimated using individual case-basis valuations and statistical analyses. Those estimates are subject to the effects of trends in loss severity and frequency. The Company utilizes various actuarially-accepted reserving methodologies in determining the continuum of expected outcomes for its reserves. These methodologies utilize various inputs, including management’s initial expected loss ratio (the ratio of losses and loss adjustment expenses incurred to net earned premiums), expected reporting patterns and payment patterns for losses and loss adjustment expenses (based on insurance industry data and the Company’s own experience), and the Company’s actual paid and reported losses and loss adjustment expenses. An internal actuary reviews these results and (after applying appropriate professional judgment and other actuarial techniques that are considered necessary) presents recommendations to the Company’s management. Management uses this information and its judgment to make decisions on the final recorded reserve for losses and loss adjustment expenses. Management believes that the use of judgment is necessary to arrive at a best estimate for the reserve for losses and loss adjustment expenses given the long-tailed nature of the business generally written by the Company and the limited operating experience of the Casualty Reinsurance segment, the fronting and program business in the Specialty Admitted Insurance segment, and the commercial auto business in the Excess and Surplus Lines segment. Catastrophes of significant magnitude, including hurricanes and earthquakes, involve complex coverage issues. In estimating the reserve for losses and loss adjustment expenses for these catastrophes, management uses case reserve estimates based on information obtained from site inspections by the Company’s adjustors and the terms of coverage provided in the policies. Management estimates reserves for incurred but not reported claims for these catastrophes using judgment based on an assessment of the Company’s property insurance exposures where the catastrophes occur and the Company’s progress in settling claims. Although management believes that the reserve for losses and loss adjustment expenses is reasonable, it is possible that the Company’s actual incurred losses and loss adjustment expenses will not develop in a manner consistent with the assumptions inherent in the determination of these reserves. Specifically, the Company’s actual ultimate loss ratio could differ from management’s initial expected loss ratio and/or the Company’s actual reporting patterns for losses could differ from the expected reporting patterns. Accordingly, the ultimate settlement of losses and the related loss adjustment expenses may vary significantly from the estimates included in the Company’s consolidated financial statements. These estimates are reviewed continually by management and are adjusted as necessary as experience develops or new information becomes known; such adjustments are included in current operations.
Share Based Compensation	Share Based Compensation The Company expenses the fair value of share equity awards over the vesting period of the award on a straight-line basis. The Black-Scholes-Merton option pricing model is used to value the options granted (see Note 12). Forfeitures of share-based awards are recognized as they occur. As the share based compensation expense is incurred, a corresponding increase to additional paid-in capital in shareholders’ equity is recognized. Share based compensation expense is reflected in “other operating expenses” in the accompanying consolidated statements of income and comprehensive income.
Variable Interest Entities	Variable Interest Entities Entities that do not have sufficient equity at risk to allow the entity to finance its activities without additional financial support or in which the equity investors, as a group, do not have the characteristic of a controlling financial interest are referred to as variable interest entities (“VIE”). A VIE is consolidated by the variable interest holder that is determined to have the controlling financial interest (primary beneficiary) as a result of having both the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE’s capital structure, contractual terms, nature of the VIE’s operations and purpose, and the Company’s relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE. The Company reassesses its VIE determination with respect to an entity on an ongoing basis.
Earnings Per Share	Earnings Per Share Basic earnings per share excludes dilution and is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted earnings per share reflects the dilution that could occur if securities or other contracts to issue common shares or common share equivalents were exercised or converted into common shares as calculated using the treasury stock method. When inclusion of common share equivalents increases the earnings per share or reduces the loss per share, the effect on earnings is anti-dilutive, and the diluted net earnings or net loss per share is computed excluding these common share equivalents.
Adopted Accounting Standards	Adopted Accounting Standards On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , using the modified retrospective approach, by which a cumulative-effect adjustment was made to retained earnings as of the date of adoption. This update requires financial assets measured at amortized cost, such as bank loan participations held for investment, to be presented at the net amount expected to be collected by means of an allowance for credit losses that is reflected in net income. Credit losses relating to available-for-sale debt securities are recorded through an allowance for credit losses, with the amount of the allowance limited to the amount by which fair value is below amortized cost. In connection with the adoption of this ASU, the Company elected the fair value option in accounting for bank loan participations effective January 1, 2020. The targeted transition relief offered by ASU 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief was applied to elect the fair value option to account for bank loan participations already held at the January 1, 2020 date of adoption. Under the fair value option, bank loan participations are measured at fair value, and changes in unrealized gains and losses in bank loan participations are reported in our income statement as net realized and unrealized gains (losses) on investments. At adoption on January 1, 2020, the Company reduced the carrying value of its bank loan portfolio to fair value through an $8.4 million adjustment with a $7.8 million (net of tax) cumulative effect adjustment to reduce retained earnings. Upon adoption of this ASU, the Company established an allowance for credit losses on reinsurance balances through a $265,000 (net of tax) cumulative effect adjustment to retained earnings. Because we purchase reinsurance from financially strong reinsurers or we have collateral securing the recoverables, the effect of adoption was not material to our financial position.
Leases	Operating lease costs are primarily comprised of rental expense for operating leases. Rental expense is recognized on a straight line basis over the lease term and includes amortization of the right-of-use lease asset and imputed interest on the lease liability. Operating lease costs are included in other operating expenses in the Company's consolidated statements of income and comprehensive income.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of reconciliation of numerator and denominator of basic and diluted earnings per share	The following represents a reconciliation of the numerator and denominator of the basic and diluted earnings per share computations contained in the consolidated financial statements. Net Income Weighted-Average Earnings (in thousands, except per share data) Year ended December 31, 2020 Basic $ 4,824 30,552,210 $ 0.16 Common share equivalents — 332,206 — Diluted $ 4,824 30,884,416 $ 0.16 Year ended December 31, 2019 Basic $ 38,339 30,275,184 $ 1.27 Common share equivalents — 398,740 (0.02) Diluted $ 38,339 30,673,924 $ 1.25 Year ended December 31, 2018 Basic $ 63,830 29,887,990 $ 2.14 Common share equivalents — 419,111 (0.03) Diluted $ 63,830 30,307,101 $ 2.11

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of summary of available-for-sale investments	The Company’s available-for-sale fixed maturity securities are summarized as follows: Cost or Gross Gross Fair (in thousands) December 31, 2020 Fixed maturity securities: State and municipal $ 277,241 $ 19,203 $ (39) $ 296,405 Residential mortgage-backed 286,104 7,784 (40) 293,848 Corporate 715,145 52,098 (421) 766,822 Commercial mortgage and asset-backed 314,911 12,611 (803) 326,719 U.S. Treasury securities and obligations guaranteed by the U.S. government 97,489 2,360 (1) 99,848 Total fixed maturity securities, available-for-sale $ 1,690,890 $ 94,056 $ (1,304) $ 1,783,642 December 31, 2019 Fixed maturity securities: State and municipal $ 159,894 $ 7,949 $ (742) $ 167,101 Residential mortgage-backed 261,524 3,244 (622) 264,146 Corporate 611,304 21,306 (389) 632,221 Commercial mortgage and asset-backed 249,309 3,954 (806) 252,457 U.S. Treasury securities and obligations guaranteed by the U.S. government 114,477 1,229 (39) 115,667 Redeemable preferred stock 2,025 9 — 2,034 Total fixed maturity securities, available-for-sale $ 1,398,533 $ 37,691 $ (2,598) $ 1,433,626
Schedule of summary of available-for-sale investments by contractual maturity	The amortized cost and fair value of available-for-sale investments in fixed maturity securities at December 31, 2020 are summarized, by contractual maturity, as follows: Cost or Fair (in thousands) One year or less $ 115,048 $ 116,404 After one year through five years 457,434 485,506 After five years through ten years 283,761 306,655 After ten years 233,632 254,510 Residential mortgage-backed 286,104 293,848 Commercial mortgage and asset-backed 314,911 326,719 Total $ 1,690,890 $ 1,783,642
Schedule of gross unrealized losses and fair value for available-for-sale securities	The following table shows the Company’s gross unrealized losses and fair value for available-for-sale securities aggregated by investment category and the length of time that individual securities have been in a continuous unrealized loss position: Less Than 12 Months 12 Months or More Total Fair Gross Fair Gross Fair Gross (in thousands) December 31, 2020 Fixed maturity securities: State and municipal $ 7,193 $ (39) $ — $ — $ 7,193 $ (39) Residential mortgage-backed 3,649 (40) — — 3,649 (40) Corporate 28,607 (421) — — 28,607 (421) Commercial mortgage and asset-backed 18,427 (447) 38,802 (356) 57,229 (803) U.S. Treasury securities and obligations guaranteed by the U.S. government 2,291 (1) — — 2,291 (1) Total fixed maturity securities, available-for-sale $ 60,167 $ (948) $ 38,802 $ (356) $ 98,969 $ (1,304) December 31, 2019 Fixed maturity securities: State and municipal $ 30,028 $ (741) $ 667 $ (1) $ 30,695 $ (742) Residential mortgage-backed 23,632 (78) 37,363 (544) 60,995 (622) Corporate 45,550 (365) 9,933 (24) 55,483 (389) Commercial mortgage and asset-backed 46,434 (406) 56,720 (400) 103,154 (806) U.S. Treasury securities and obligations guaranteed by the U.S. government 8,474 (22) 7,168 (17) 15,642 (39) Total fixed maturity securities, available-for-sale $ 154,118 $ (1,612) $ 111,851 $ (986) $ 265,969 $ (2,598)
Schedule of major categories of the company' s net investment income	Major categories of the Company’s net investment income are summarized as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Fixed maturity securities $ 45,070 $ 39,875 $ 34,129 Bank loan participations 12,150 19,772 18,279 Equity securities 4,800 5,262 5,240 Other invested assets 9,181 6,254 5,165 Cash, cash equivalents, restricted cash equivalents, and short-term investments 6,619 9,210 2,677 Gross investment income 77,820 80,373 65,490 Investment expense (4,452) (4,721) (4,234) Net investment income $ 73,368 $ 75,652 $ 61,256
Schedule of summary of realized gains and losses	The Company’s net realized and unrealized losses and gains on investments are summarized as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Fixed maturity securities: Gross realized gains $ 1,098 $ 1,575 $ 422 Gross realized losses (53) (494) (976) 1,045 1,081 (554) Equity securities: Gross realized gains — 11 — Gross realized losses (1,441) (232) (62) Changes in fair values of equity securities (215) 6,257 (5,970) (1,656) 6,036 (6,032) Bank loan participations: Gross realized gains 554 846 2,279 Gross realized losses (17,286) (10,902) (1,166) Changes in fair values of bank loan participations 1,318 — — (15,414) (10,056) 1,113 Short-term investments and other: Gross realized gains 77 21 — Gross realized losses (2) (1) (6) Changes in fair values of short-term investments and other (80) — — (5) 20 (6) Total $ (16,030) $ (2,919) $ (5,479)
Schedule of available-for-sale gross unrealized gains or losses	The following table summarizes the change in the Company’s available-for-sale gross unrealized gains or losses by investment type: Year Ended December 31, 2020 2019 2018 (in thousands) Change in gross unrealized gains (losses): Fixed maturity securities $ 57,659 $ 50,300 $ (22,643) Total $ 57,659 $ 50,300 $ (22,643)
Schedule of other invested assets	The Company invests selectively in private debt and equity opportunities. These investments, which together comprise the Company’s other invested assets, are primarily focused in renewable energy, limited partnerships, and bank holding companies. Carrying Value Investment Income December 31, Year Ended December 31, 2020 2019 2020 2019 2018 (in thousands) (in thousands) Renewable energy LLCs (a) $ 30,145 $ 31,219 $ 2,016 $ 2,181 $ 2,974 Renewable energy notes receivable (b) — 8,750 5,630 1,313 1,282 Limited partnerships (c) 11,903 16,741 1,192 2,417 566 Bank holding companies (d) 4,500 4,500 343 343 343 Total other invested assets $ 46,548 $ 61,210 $ 9,181 $ 6,254 $ 5,165 (a) The Company’s Corporate and Other segment owns equity interests ranging from 2.6% to 32.6% in various LLCs whose principal objective is capital appreciation and income generation from owning and operating renewable energy production facilities (wind and solar). The LLCs are managed by an entity for which two of our recent former directors serve as officers, and the Company’s Non-Executive Chairman has invested in certain of these LLCs. The equity method is used to account for the Company’s LLC investments. Income for the LLCs primarily reflects adjustments to the carrying values of investments in renewable energy projects to their determined fair values. The fair value adjustments are included in revenues for the LLCs. Expenses for the LLCs are not significant and are comprised of administrative and interest expenses. The Company received cash distributions from these investments totaling $3.1 million and $757,000 for the years ended December 31, 2020 and 2019, respectively. (b) The Company's Corporate and Other segment has invested in notes receivable for renewable energy projects. At December 31, 2019, the Company held one $8.8 million note issued by an entity for which two of our recent former directors serve as officers . During the current year ended December 31, 2020, the Company received the total principal balance of $8.8 million plus a $5.3 million gain at maturity. Interest on the note was fixed at 15%. Income on the note was $5.6 million, $1.3 million, and $1.3 million for the years ended December 31, 2020, 2019, and 2018, respectively. (c) The Company owns investments in limited partnerships that invest in concentrated portfolios including publicly-traded small cap equities, loans of middle market private equity sponsored companies, equity tranches of collateralized loan obligations ("CLOs"), and tranches of distressed home loans. Income from the partnerships is recognized under the equity method of accounting. The Company’s Corporate and Other segment held investments in limited partnerships with a carrying value of $7.8 million and $3.4 million at December 31, 2020 and 2019, and recognized investment income of $1.3 million, $327,000, and $70,000 for the years ended December 31, 2020, 2019 and 2018, respectively. The Company’s Excess and Surplus Lines segment holds investments in limited partnerships of $4.1 million and $13.3 million at December 31, 2020 and 2019, respectively. Investment losses of $69,000 were recognized on these investments for the year ended December 31, 2020. Investment income of $2.1 million and $496,000 were recognized on these investments for the years ended December 31, 2019 and 2018, respectively. At December 31, 2020, the Company’s Excess and Surplus Lines segment has outstanding commitments to invest another $3.7 million in these limited partnerships and $5.0 million to a newly acquired limited partnership, which will request funding starting in 2021. (d) The Company's Corporate and Other segment holds $4.5 million of subordinated notes issued by a bank holding company for which the Company’s Non-Executive Chairman was previously the Lead Independent Director and an investor and for which one of the Company’s directors was an investor and is currently a lender (the "Bank Holding Company"). Interest on

Deferred Policy Acquisition C_2

Deferred Policy Acquisition Costs (Tables)	12 Months Ended
	Dec. 31, 2020
Deferred Policy Acquisition Costs Disclosures [Abstract]
Schedule of deferred policy acquisition costs	An analysis of deferred policy acquisition costs is as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Balance at beginning of period $ 62,006 $ 54,450 $ 72,365 Policy acquisition costs deferred: Commissions 51,306 67,303 72,473 Underwriting and other issue expenses 25,219 24,146 20,715 76,525 91,449 93,188 Amortization of policy acquisition costs (75,578) (83,893) (111,103) Net change 947 7,556 (17,915) Balance at end of period $ 62,953 $ 62,006 $ 54,450

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of gross carrying amounts and accumulated amortization	The gross carrying amounts and accumulated amortization for each major specifically identifiable intangible asset class were as follows: December 31, 2020 2019 Weighted- Gross Accumulated Gross Accumulated (in thousands) Trademarks Indefinite $ 22,200 $ — $ 22,200 $ — Insurance licenses and authorities Indefinite 8,964 — 8,964 — Identifiable intangibles not subject to amortization 31,164 — 31,164 — Broker relationships 24.6 11,611 6,373 11,611 5,835 Identifiable intangible assets subject to amortization 11,611 6,373 11,611 5,835 $ 42,775 $ 6,373 $ 42,775 $ 5,835
Schedule of future estimated amortization	Future estimated amortization of specifically identifiable intangible assets as of December 31, 2020 is as follows ( in thousands) : 2021 $ 363 2022 363 2023 363 2024 363 2025 363 Thereafter 3,423 Total $ 5,238
Schedule of acquired indefinite-lived intangible assets	The table below summarizes the changes in the net carrying values of intangible assets by segment for 2020: December 31, 2019 December 31, 2020 Net Carrying Amortization Impairment Net Carrying (in thousands) Excess and Surplus Lines Trademarks $ 19,700 $ — $ — $ 19,700 Insurance licenses and authorities 4,900 — — 4,900 Broker relationships 5,603 (366) — 5,237 30,203 (366) — 29,837 Specialty Admitted Insurance Trademarks 2,500 — — 2,500 Insurance licenses and authorities 4,065 — — 4,065 Broker relationships 172 (172) — — 6,737 (172) — 6,565 Total identifiable intangible assets $ 36,940 $ (538) $ — $ 36,402 The table below summarizes the changes in the net carrying values of intangible assets by segment for 2019: December 31, 2018 December 31, 2019 Net Carrying Amortization Impairment Net Carrying (in thousands) Excess and Surplus Lines Trademarks $ 19,700 $ — $ — $ 19,700 Insurance licenses and authorities 4,900 — — 4,900 Broker relationships 5,965 (362) — 5,603 30,565 (362) — 30,203 Specialty Admitted Insurance Trademarks 2,500 — — 2,500 Insurance licenses and authorities 4,065 — — 4,065 Broker relationships 407 (235) — 172 6,972 (235) — 6,737 Total identifiable intangible assets $ 37,537 $ (597) $ — $ 36,940
Schedule of acquired finite-lived intangible assets	The table below summarizes the changes in the net carrying values of intangible assets by segment for 2020: December 31, 2019 December 31, 2020 Net Carrying Amortization Impairment Net Carrying (in thousands) Excess and Surplus Lines Trademarks $ 19,700 $ — $ — $ 19,700 Insurance licenses and authorities 4,900 — — 4,900 Broker relationships 5,603 (366) — 5,237 30,203 (366) — 29,837 Specialty Admitted Insurance Trademarks 2,500 — — 2,500 Insurance licenses and authorities 4,065 — — 4,065 Broker relationships 172 (172) — — 6,737 (172) — 6,565 Total identifiable intangible assets $ 36,940 $ (538) $ — $ 36,402 The table below summarizes the changes in the net carrying values of intangible assets by segment for 2019: December 31, 2018 December 31, 2019 Net Carrying Amortization Impairment Net Carrying (in thousands) Excess and Surplus Lines Trademarks $ 19,700 $ — $ — $ 19,700 Insurance licenses and authorities 4,900 — — 4,900 Broker relationships 5,965 (362) — 5,603 30,565 (362) — 30,203 Specialty Admitted Insurance Trademarks 2,500 — — 2,500 Insurance licenses and authorities 4,065 — — 4,065 Broker relationships 407 (235) — 172 6,972 (235) — 6,737 Total identifiable intangible assets $ 37,537 $ (597) $ — $ 36,940

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of property and equipment, net	Property and equipment, net of accumulated depreciation, is included in "other assets" on the consolidated balance sheets and consists of the following: December 31, 2020 2019 (in thousands) Electronic data processing hardware and software $ 3,238 $ 7,007 Furniture and equipment 2,025 2,180 Property and equipment, cost basis 5,263 9,187 Accumulated depreciation (3,975) (7,419) Property and equipment, net $ 1,288 $ 1,768

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Summary of Lease Maturities	The table below summarizes maturities of the Company’s operating lease liabilities as of December 31, 2020, which reconciles to total lease liabilities included in other liabilities on the Company’s consolidated balance sheet: Years ending December 31, (in thousands) 2021 $ 3,993 2022 3,800 2023 3,619 2024 2,422 2025 2,349 Thereafter 197 Total lease payments 16,380 Less imputed interest (1,464) Total operating lease liabilities $ 14,916

Reserve for Losses and Loss A_2

Reserve for Losses and Loss Adjustment Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Liability for Claims and Claims Adjustment Expense [Abstract]
Schedule of reconciliation of beginning and ending reserve balances for losses and loss adjustment expenses	Year Ended December 31, 2020 2019 2018 (in thousands) Reserve for losses and loss adjustment expenses net of reinsurance recoverables at beginning of period $ 1,377,461 $ 1,194,088 $ 989,825 Add: Incurred losses and loss adjustment expenses net of reinsurance: Current year 386,341 603,094 582,604 Prior years 92,204 69,008 17,672 Total incurred losses and loss and adjustment expenses 478,545 672,102 600,276 Deduct: Loss and loss adjustment expense payments net of reinsurance: Current year 31,952 75,249 86,355 Prior years 437,993 413,480 309,658 Total loss and loss adjustment expense payments 469,945 488,729 396,013 Reserve for losses and loss adjustment expenses net of reinsurance recoverables at end of period 1,386,061 1,377,461 1,194,088 Add: Reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period 806,019 668,045 467,371 Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period $ 2,192,080 $ 2,045,506 $ 1,661,459
Schedule of incurred and cumulative paid losses and loss adjustment expenses, net of reinsurance	Excess and Surplus Lines — Excluding Commercial Auto Incurred losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 111,190 $ 119,927 $ 114,473 $ 106,564 $ 106,381 $ 106,130 $ 106,643 $ 106,536 $ 105,173 $ 104,280 2012 97,908 98,672 97,829 96,497 97,306 99,619 101,271 103,061 106,118 2013 96,729 96,064 85,433 81,009 82,830 83,855 82,732 82,517 2014 114,942 104,092 90,267 82,232 84,074 88,904 90,191 2015 126,443 113,417 104,847 102,434 103,688 110,466 2016 138,507 125,093 126,050 126,971 125,097 2017 144,349 131,897 132,136 124,265 2018 167,004 158,458 146,633 2019 214,653 194,759 2020 239,897 Total $ 1,324,223 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 27,684 $ 53,109 $ 72,732 $ 81,696 $ 90,884 $ 94,998 $ 98,684 $ 99,798 $ 101,728 $ 101,969 2012 6,944 33,757 49,604 63,216 74,869 82,545 88,812 94,588 99,628 2013 3,867 14,509 30,382 44,421 59,641 66,553 71,035 74,635 2014 3,412 16,969 28,212 43,891 58,774 71,549 76,523 2015 4,048 17,164 34,801 55,911 73,455 87,344 2016 5,180 22,852 46,045 70,105 90,166 2017 5,290 22,956 42,764 64,924 2018 6,000 26,160 50,679 2019 8,235 31,346 2020 8,642 Total $ 685,856 All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance (46 claims outstanding) $ 7,946 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 646,313 Excess and Surplus Lines — Commercial Auto Incurred losses and adjustment expenses, net of reinsurance (in thousands) Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2013 $ 1,255 $ 1,300 $ 1,451 $ 1,351 $ 1,301 $ 1,277 $ 1,277 $ 1,277 2014 20,487 14,071 17,233 18,953 19,779 18,303 19,196 2015 30,109 33,113 35,149 36,139 36,636 37,839 2016 74,340 109,286 126,791 147,122 157,712 2017 207,355 208,743 272,421 319,472 2018 255,881 230,220 283,408 2019 262,306 240,773 2020 19,133 Total $ 1,078,810 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2013 $ 60 $ 1,182 $ 1,285 $ 1,291 $ 1,275 $ 1,275 $ 1,275 $ 1,275 2014 6,166 8,645 12,679 16,359 18,678 17,745 18,301 2015 8,356 15,234 24,282 31,592 34,819 35,983 2016 18,295 54,054 89,381 125,108 141,545 2017 41,467 107,377 192,961 252,169 2018 45,136 119,099 184,686 2019 44,225 107,182 2020 628 Total $ 741,769 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 337,041 Specialty Admitted — Individual Risk Workers’ Compensation Incurred losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 37,834 $ 41,421 $ 40,154 $ 38,999 $ 38,311 $ 37,455 $ 36,594 $ 36,593 $ 36,593 $ 35,252 2012 32,116 32,420 31,490 29,689 28,255 28,174 28,186 28,186 27,741 2013 12,525 13,668 12,786 11,578 10,907 10,909 10,909 10,598 2014 16,638 16,652 14,620 13,890 12,704 12,704 12,573 2015 20,938 21,274 19,741 18,376 17,626 16,492 2016 21,678 20,299 18,050 15,800 14,050 2017 24,869 22,071 19,779 18,810 2018 16,432 16,288 16,038 2019 20,253 21,056 2020 20,137 Total $ 192,747 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 10,123 $ 23,127 $ 29,021 $ 33,204 $ 34,240 $ 34,287 $ 34,334 $ 34,614 $ 34,638 $ 34,665 2012 9,222 20,308 24,755 26,435 26,897 26,932 26,963 26,994 27,128 2013 4,487 8,723 9,846 10,246 10,263 10,309 10,337 10,335 2014 4,633 10,648 12,041 12,236 12,282 12,282 12,276 2015 6,604 13,285 15,118 15,889 15,901 16,068 2016 4,664 10,227 12,135 12,432 12,481 2017 6,546 12,782 14,285 15,195 2018 4,497 9,034 11,412 2019 5,473 13,776 2020 7,394 Total $ 160,730 All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance (4 claims outstanding) $ 1,237 Outstanding losses and loss adjustment expenses assumed from involuntary workers’ compensation pools $ 4,358 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 37,612 Specialty Admitted — Fronting and Programs Incurred losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2013 $ 104 $ 80 $ 52 $ 52 $ 52 $ 52 $ 52 $ 52 2014 3,460 3,468 3,818 3,425 3,228 3,083 3,081 2015 7,136 9,632 9,358 8,974 8,384 8,444 2016 11,542 15,670 14,682 15,522 14,468 2017 21,229 24,271 25,201 24,728 2018 21,758 20,677 19,822 2019 18,832 19,020 2020 25,433 Total $ 115,048 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2013 $ 28 $ 52 $ 52 $ 52 $ 52 $ 52 $ 52 $ 52 2014 883 1,687 2,369 2,728 2,854 2,916 2,917 2015 2,058 4,666 6,165 6,919 7,329 7,654 2016 1,894 5,123 6,888 10,732 10,896 2017 1,223 6,682 13,065 15,854 2018 885 4,972 10,495 2019 4,358 5,125 2020 5,375 Total $ 58,368 All outstanding losses and loss adjustment expenses, net of reinsurance $ 56,680 Outstanding losses and loss adjustment expenses, assumed from involuntary pools $ 601 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 57,281 Casualty Reinsurance Incurred losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 114,908 $ 103,123 $ 97,366 $ 97,812 $ 98,993 $ 99,282 $ 101,276 $ 103,196 $ 105,333 $ 106,226 2012 148,251 132,388 131,281 135,594 136,813 139,978 143,305 146,045 147,413 2013 133,230 130,361 131,352 134,446 137,801 143,124 146,760 149,682 2014 118,881 115,927 114,636 116,981 121,200 126,160 130,822 2015 119,157 108,870 108,699 109,117 114,517 120,185 2016 112,759 105,533 103,544 108,222 114,979 2017 134,628 128,472 129,800 138,831 2018 121,529 119,098 125,715 2019 86,022 85,549 2020 80,374 Total $ 1,199,776 Cumulative paid losses and loss adjustment expenses, net of reinsurance (in thousands) Accident Year 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2011 $ 48,688 $ 61,922 $ 68,616 $ 78,164 $ 87,267 $ 90,287 $ 94,627 $ 97,715 $ 99,511 $ 101,209 2012 73,124 81,859 97,215 113,943 121,026 128,567 133,606 137,430 139,719 2013 59,756 75,094 93,902 108,396 119,256 127,732 134,644 139,250 2014 41,421 58,601 76,302 89,899 101,366 110,374 117,971 2015 40,021 53,986 68,002 80,208 90,661 100,548 2016 36,268 50,905 65,409 78,145 90,356 2017 47,739 72,891 90,117 106,942 2018 30,903 50,274 69,123 2019 12,646 25,453 2020 5,589 Total $ 896,160 All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance $ 4,198 Total outstanding losses and loss adjustment expenses, net of reinsurance $ 307,814
Schedule of reserve for losses and loss adjustment expenses	The reconciliation of the net incurred and paid claims development tables to the reserve for losses and loss adjustment expenses in the consolidated balance sheet at December 31, 2020 is as follows (in thousands): E&S – excluding commercial auto $ 646,313 E&S – commercial auto 337,041 Specialty Admitted – individual risk workers’ compensation 37,612 Specialty Admitted – fronting and programs 57,281 Casualty Reinsurance 307,814 Net reserve for losses and loss adjustment expenses 1,386,061 Reinsurance recoverables on unpaid losses (gross of $335,000 allowance for credit losses on reinsurance recoverables) 806,019 Gross reserve for losses and loss adjustment expenses $ 2,192,080
Schedule of average annual percentage payouts of incurred claims by age, net of reinsurance	The following is unaudited supplementary information about average annual percentage payouts of incurred claims by age, net of reinsurance, for the Excess and Surplus Lines segment and the Specialty Admitted Insurance segments as of December 31, 2020. Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 E&S – excluding commercial auto 9.0 % 15.4 % 17.2 % 18.3 % 15.0 % 7.9 % 5.4 % 4.0 % 2.2 % 1.8 % E&S – commercial auto 18.2 % 38.3 % 16.4 % 13.7 % 7.7 % 3.0 % 0.3 % 2.3 % Specialty Admitted – individual risk workers’ compensation 27.1 % 31.6 % 15.3 % 9.0 % 6.3 % 3.4 % 2.2 % 1.2 % 1.2 % 0.8 % Specialty Admitted – fronting and programs 17.4 % 20.5 % 25.4 % 14.7 % 9.8 % 7.3 % 2.2 % 2.6 % Casualty Reinsurance 22.1 % 15.9 % 11.6 % 8.5 % 6.6 % 5.2 % 4.1 % 3.5 % 3.4 % 2.9 %
Schedule of incurred but not reported liabilities and claims frequency	The table below provides information on IBNR liabilities and claims frequency for: (1) the Excess and Surplus Lines segment split between commercial auto and all non commercial auto, and (2) the Specialty Admitted Insurance segment split between individual risk workers’ compensation and fronting and programs: Excess and Surplus Lines — Excluding Commercial Auto Accident Year Incurred Losses IBNR Cumulative # of ($ in thousands) 2011 $ 104,280 $ 2,038 1,488 2012 106,118 1,586 1,850 2013 82,517 3,488 2,480 2014 90,191 6,804 2,198 2015 110,466 5,409 2,587 2016 125,097 15,213 3,023 2017 124,265 29,548 3,085 2018 146,633 52,940 4,267 2019 194,759 123,212 4,950 2020 239,897 206,389 3,115 Excess and Surplus Lines — Commercial Auto Accident Year Incurred Losses IBNR Cumulative # of ($ in thousands) 2013 $ 1,277 $ 1 54 2014 19,196 249 7,764 2015 37,839 639 41,766 2016 157,712 3,555 89,084 2017 319,472 4,303 134,055 2018 283,408 9,947 97,076 2019 240,773 40,372 70,707 2020 19,133 16,942 498 Specialty Admitted - Individual Risk Workers’ Compensation Accident Year Incurred Losses IBNR Cumulative # of ($ in thousands) 2011 $ 35,252 $ 532 $ 1,814 2012 27,741 602 1,323 2013 10,598 262 540 2014 12,573 298 850 2015 16,492 423 975 2016 14,050 1,527 836 2017 18,810 3,436 1,093 2018 16,038 4,020 1,238 2019 21,056 2,989 1,548 2020 20,137 2,842 1,305   Specialty Admitted — Fronting and Programs Accident Year Incurred Losses IBNR Cumulative # of ($ in thousands) 2013 $ 52 $ — 22 2014 3,081 150 858 2015 8,444 452 1,363 2016 14,468 1,900 2,815 2017 24,728 5,244 6,765 2018 19,822 4,998 7,318 2019 19,020 9,119 7,941 2020 25,433 14,743 6,956 The table below provides information on IBNR liabilities for the Casualty Reinsurance segment: Accident Year Incurred Losses IBNR ($ in thousands) 2011 $ 106,226 $ 819 2012 147,413 1,566 2013 149,682 2,427 2014 130,822 3,200 2015 120,185 5,147 2016 114,979 9,091 2017 138,831 17,173 2018 125,715 31,058 2019 85,549 49,717 2020 80,374 61,595

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2020
Reinsurance Disclosures [Abstract]
Schedule of premiums written, premiums earned, and losses and loss adjustment expenses	Premiums written, premiums earned, and losses and loss adjustment expenses incurred are summarized as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Written premiums: Direct $ 1,103,994 $ 1,305,948 $ 1,027,222 Assumed 153,006 164,787 139,551 Ceded (609,226) (574,585) (404,101) Net $ 647,774 $ 896,150 $ 762,672 Earned premiums: Direct $ 1,005,138 $ 1,182,501 $ 990,221 Assumed 145,867 150,330 208,192 Ceded (544,199) (509,085) (383,015) Net $ 606,806 $ 823,746 $ 815,398 Losses and loss adjustment expenses: Direct $ 709,545 $ 953,548 $ 769,490 Assumed 125,096 113,843 131,346 Ceded (356,096) (395,289) (300,560) Net $ 478,545 $ 672,102 $ 600,276

Junior Subordinated Debt (Table

Junior Subordinated Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Subordinated Borrowings [Abstract]
Schedule of Junior Subordinated Debt	The following table summarizes the nature and terms of the Junior Subordinated Debt and Trust Preferred Securities: James River James River James River James River Franklin ($ in thousands) Issue date May 26, December 15, June 15, December 11, January 10, Principal amount of Trust Preferred Securities $7,000 $15,000 $20,000 $54,000 $30,000 Principal amount of Junior Subordinated Debt $7,217 $15,464 $20,619 $55,670 $30,928 Carrying amount of Junior Subordinated Debt net of repurchases $7,217 $15,464 $20,619 $44,827 $15,928 Maturity date of Junior Subordinated Debt, unless accelerated earlier May 24, December 15, June 15, December 15, March 15, Trust common stock $217 $464 $619 $1,670 $928 Interest rate, per annum Three-Month LIBOR plus 4.0% Three-Month LIBOR plus 3.4% Three-Month LIBOR plus 3.0% Three-Month LIBOR plus 3.1% Three-Month LIBOR plus 4.0%

Capital Stock (Tables)

Capital Stock (Tables)	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
Schedule of cash dividends declared	The Board of Directors declared the following cash dividends in 2020, 2019, and 2018: Date of Dividend per Payable to Shareholders Payment Date Total Amount (thousands) 2020 February 19, 2020 $0.30 March 16, 2020 March 31, 2020 $ 9,269 April 28, 2020 $0.30 June 15, 2020 June 30, 2020 $ 9,271 July 28, 2020 $0.30 September 14, 2020 September 30, 2020 $ 9,292 October 27, 2020 $0.30 December 14, 2020 December 31, 2020 $ 9,305 Total $1.20 $ 37,137 2019 February 20, 2019 $0.30 March 11, 2019 March 29, 2019 $ 9,146 April 30, 2019 $0.30 June 10, 2019 June 28, 2019 $ 9,205 July 30, 2019 $0.30 September 16, 2019 September 30, 2019 $ 9,231 November 5, 2019 $0.30 December 16, 2019 December 31, 2019 $ 9,229 Total $1.20 $ 36,811 2018 February 22, 2018 $0.30 March 12, 2018 March 30, 2018 $ 9,049 May 1, 2018 $0.30 June 11, 2018 June 29, 2018 $ 9,066 August 1, 2018 $0.30 September 10, 2018 September 28, 2018 $ 9,081 November 7, 2018 $0.30 December 14, 2018 December 28, 2018 $ 9,089 Total $1.20 $ 36,285

Equity Awards (Tables)

Equity Awards (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Schedule of summary of option activity	The following table summarizes the option activity: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Outstanding: Beginning of year 643,851 $ 30.41 1,115,324 $ 29.02 1,479,236 $ 27.81 Granted — $ — — $ — — $ — Exercised (180,527) $ 25.70 (459,415) $ 26.87 (308,025) $ 22.01 Forfeited — $ — (12,058) $ 36.84 (55,887) $ 35.69 End of year 463,324 $ 32.25 643,851 $ 30.41 1,115,324 $ 29.02 Exercisable, end of year 463,324 $ 32.25 590,340 $ 29.34 814,421 $ 26.46
Schedule of value of the options granted was estimated at the date of grant using the Black-Scholes-Merton	The value of the options granted was estimated at the date of grant using the Black-Scholes-Merton option pricing model.
Schedule of summary of RSU activity	The following table summarizes RSU activity: Year Ended December 31, 2020 2019 2018 Shares Weighted- Shares Weighted- Shares Weighted- Unvested, beginning of year 340,368 $ 41.50 300,142 $ 39.22 178,882 $ 37.93 Granted 272,608 $ 45.11 197,078 $ 42.56 227,481 $ 39.74 Vested (165,344) $ 41.49 (134,407) $ 37.99 (83,384) $ 37.61 Forfeited (47,776) $ 44.57 (22,445) $ 41.32 (22,837) $ 40.21 Unvested, end of year 399,856 $ 43.59 340,368 $ 41.50 300,142 $ 39.22
Schedule of summary of share based compensation amount of expense and related tax benefit	The amount of expense and related tax benefit is summarized below: Year Ended December 31, 2020 2019 2018 (in thousands) Share based compensation expense $ 7,625 $ 7,178 $ 6,228 U.S. tax benefit on share based compensation expense $ 1,001 $ 872 $ 716

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of weighted-average tax rate as well as a reconciliation to total tax expense	A reconciliation of the difference between the Company’s Federal income tax provision on U.S. income and the expected Federal tax provision on U.S. income using the weighted-average tax rate as well as a reconciliation to total tax expense is as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Federal income tax expense at applicable statutory rates $ 5,272 $ 14,843 $ 7,875 Tax-exempt investment income (260) (230) (272) Dividends received deduction (283) (307) (307) Excess tax benefits on share based compensation (679) (1,099) (567) Effect of tax rate reduction on deferred tax liability — — 220 Base Erosion and Anti-Abuse Tax 2,843 — — Other 17 99 145 Federal income tax expense $ 6,910 $ 13,306 $ 7,094 U.S. state income tax expense (benefit) 203 222 (86) Total income tax expense $ 7,113 $ 13,528 $ 7,008
Schedule of deferred tax assets (liabilities) at the current prevailing corporate income tax rate	The significant components of net deferred tax assets (liabilities) at the corporate income tax rate of 21% for the years ended December 31, 2020 and 2019 are summarized as follows: December 31, 2020 2019 (in thousands) Deferred tax assets: Accrued compensation expenses $ 2,308 $ 2,563 Reserve for losses and loss adjustment expenses 14,265 12,286 Unearned premiums 9,753 8,226 Share based compensation 1,427 1,482 Allowance for doubtful accounts 2,130 1,188 Property and equipment 213 16 Other 4,810 1,974 Total deferred tax assets 34,906 27,735 Deferred tax liabilities: Intangible assets 7,324 7,381 Net unrealized gains 12,201 5,792 Deferred policy acquisition costs 4,786 4,448 Equity method investments 8,839 9,316 Other 2,861 134 Total deferred tax liabilities 36,011 27,071 Net deferred tax (liabilities) assets $ (1,105) $ 664

Other Operating Expenses and _2

Other Operating Expenses and Other Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Other Operating Expenses And Other Expenses [Abstract]
Schedule of other operating expenses	Other operating expenses consist of the following: Year Ended December 31, 2020 2019 2018 (in thousands) Amortization of policy acquisition costs $ 75,578 $ 83,893 $ 111,103 Other underwriting expenses of the insurance segments 60,502 59,351 63,029 Other operating expenses of the Corporate and Other segment 29,418 27,664 26,903 Total $ 165,498 $ 170,908 $ 201,035
Schedule of other expenses	Other expenses consist of the following: Year Ended December 31, 2020 2019 2018 (in thousands) Employee severance $ 1,967 $ 1,055 $ 1,386 Income on leased building the Company was previously deemed to own for accounting purposes — — (623) Legal and professional services related to secondary share offerings — — 337 Other 171 — — Impairment of intangible asset — — 200 Total $ 2,138 $ 1,055 $ 1,300

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2020
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of components of comprehensive income	The following table summarizes the components of other comprehensive income (loss): Year Ended December 31, 2020 2019 2018 (in thousands) Unrealized gains (losses) arising during the period, before U.S. income taxes $ 58,704 $ 51,381 $ (23,201) U.S. income taxes (6,967) (3,510) 483 Unrealized gains (losses) arising during the period, net of U.S. income taxes 51,737 47,871 (22,718) Less reclassification adjustment: Net realized investment gains (losses) 1,045 1,081 (554) U.S. income taxes (93) (152) 39 Reclassification adjustment for investment gains (losses) realized in net income 952 929 (515) Other comprehensive income (loss) $ 50,785 $ 46,942 $ (22,203)

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of summary of company's segment results	Segment results are reported prior to the effects of the intercompany reinsurance agreements between the Company’s insurance subsidiaries. All gross written premiums and net earned premiums for all periods presented were generated from policies issued to U.S. based insureds. Excess and Specialty Casualty Corporate Total (in thousands) As of and for the Year Ended December 31, 2020 Gross written premiums $ 699,143 $ 408,691 $ 149,166 $ — $ 1,257,000 Net earned premiums 415,168 57,505 134,133 — 606,806 Segment revenues 429,918 62,790 166,837 9,144 668,689 Net investment income 18,664 3,392 42,554 8,758 73,368 Interest expense — — — 10,033 10,033 Underwriting profit (loss) of operating segments 9,752 4,185 (18,364) — (4,427) Segment goodwill 181,831 — — — 181,831 Segment assets 2,208,344 907,604 1,899,328 47,796 5,063,072 As of and for the Year Ended December 31, 2019 Gross written premiums $ 922,320 $ 387,642 $ 160,773 $ — $ 1,470,735 Net earned premiums 625,528 54,338 143,880 — 823,746 Segment revenues 657,501 61,241 183,700 4,683 907,125 Net investment income 21,358 3,802 46,325 4,167 75,652 Interest expense — — — 10,596 10,596 Underwriting profit (loss) of operating segments 19,157 5,913 (7,161) — 17,909 Segment goodwill 181,831 — — — 181,831 Segment assets 2,481,934 786,433 1,699,473 56,565 5,024,405 As of and for the Year Ended Gross written premiums $ 656,538 $ 374,346 $ 135,889 $ — $ 1,166,773 Net earned premiums 555,684 55,146 204,568 — 815,398 Segment revenues 580,785 56,717 243,178 4,919 885,599 Net investment income 14,456 3,262 38,838 4,700 61,256 Interest expense — — — 11,553 11,553 Underwriting profit of operating segments 42,834 6,972 5,103 — 54,909 Segment goodwill 181,831 — — — 181,831 Segment assets 972,111 633,689 1,453,754 77,222 3,136,776
Schedule of underwriting profit (loss) of operating segments by individual segment and reconciliation to consolidated income before taxes	The following table reconciles the underwriting (loss) profit of operating segments by individual segment to income before income taxes: Year Ended December 31, 2020 2019 2018 (in thousands) Underwriting (loss) profit of the operating segments: Excess and Surplus Lines $ 9,752 $ 19,157 $ 42,834 Specialty Admitted Insurance 4,185 5,913 6,972 Casualty Reinsurance (18,364) (7,161) 5,103 Total underwriting (loss) profit of operating segments (4,427) 17,909 54,909 Other operating expenses of the Corporate and Other segment (29,418) (27,664) (26,903) Underwriting (loss) profit (33,845) (9,755) 28,006 Net investment income 73,368 75,652 61,256 Net realized and unrealized losses on investments (16,030) (2,919) (5,479) Other income 1,153 1,137 505 Other expenses (2,138) (1,055) (1,300) Interest expense (10,033) (10,596) (11,553) Amortization of intangible assets (538) (597) (597) Income before income taxes $ 11,937 $ 51,867 $ 70,838
Schedule of gross written premiums by segment and underwriting division	Gross written premiums by segment and underwriting division are presented below: Year Ended December 31, 2020 2019 2018 (in thousands) Excess Casualty $ 213,037 $ 118,954 $ 66,452 General Casualty 125,433 115,832 54,127 Manufacturers and Contractors 122,880 105,096 79,160 Energy 51,109 45,442 33,942 Excess Property 37,332 31,606 16,963 Life Sciences 35,163 24,462 16,636 Commercial Auto 30,029 405,565 322,126 Allied Health 26,918 26,713 30,450 Small Business 24,790 19,725 14,808 Environmental 17,753 16,539 10,499 Professional Liability 6,881 6,441 5,916 Sports and Entertainment 6,118 4,212 3,685 Medical Professionals 1,700 1,733 1,774 Total Excess and Surplus Lines segment 699,143 922,320 656,538 Specialty Admitted Insurance segment 408,691 387,642 374,346 Casualty Reinsurance segment 149,166 160,773 135,889 Total $ 1,257,000 $ 1,470,735 $ 1,166,773

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of assets measured at fair value on a recurring basis	Assets measured at fair value on a recurring basis as of December 31, 2020 are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ — $ 296,405 $ — $ 296,405 Residential mortgage-backed — 293,848 — 293,848 Corporate — 766,822 — 766,822 Commercial mortgage and asset-backed — 326,719 326,719 U.S. Treasury securities and obligations guaranteed by the U.S. government 99,384 464 — 99,848 Total fixed maturity securities, available-for-sale $ 99,384 $ 1,684,258 $ — $ 1,783,642 Equity securities: Preferred stock $ — $ 67,495 $ — $ 67,495 Common stock 15,793 5,015 672 21,480 Total equity securities $ 15,793 $ 72,510 $ 672 $ 88,975 Bank loan participations $ — $ 147,296 $ 308 $ 147,604 Short-term investments $ — $ 130,289 $ — $ 130,289 Assets measured at fair value on a recurring basis as of December 31, 2019 are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ — $ 167,101 $ — $ 167,101 Residential mortgage-backed — 264,146 — 264,146 Corporate — 632,221 — 632,221 Commercial mortgage and asset-backed — 252,457 — 252,457 U.S. Treasury securities and obligations guaranteed by the U.S. government 115,173 494 — 115,667 Redeemable preferred stock — 2,034 — 2,034 Total fixed maturity securities, available-for-sale $ 115,173 $ 1,318,453 $ — $ 1,433,626 Equity securities: Preferred stock $ — $ 62,747 $ — $ 62,747 Common stock 14,669 3,276 43 17,988 Total equity securities $ 14,669 $ 66,023 $ 43 $ 80,735 Short-term investments $ — $ 156,925 $ — $ 156,925
Schedule of fair value on a recurring basis using significant unobservable inputs (Level 3)	A reconciliation of the beginning and ending balances of available-for-sale fixed maturity securities, equity securities, and bank loan participations (following the Company's election of the fair value option in accounting for bank loan participations effective January 1, 2020) measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is shown below: Year Ended December 31, 2020 2019 2018 (in thousands) Beginning balance $ 43 $ 4,442 $ 4,680 Transfers in to Level 3 358 3,010 — Transfers out of Level 3 (767) (7,238) — Purchases 1,417 214 Sales — — — Maturities and calls (17) (452) Amortization of discount 2 — — Total gains or losses (realized/unrealized): Included in earnings (56) (171) — Included in other comprehensive income — — — Ending balance $ 980 $ 43 $ 4,442
Schedule of assets measured at fair value on a nonrecurring basis	Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) December 31, 2019 Bank loan participations held-for-investment $ — $ — $ 6,949 $ 6,949
Schedule of carrying value and fair value	The carrying values and fair values of financial instruments are summarized below: December 31, 2020 2019 Carrying Fair Carrying Fair (in thousands) Assets Fixed maturity securities, available-for-sale $ 1,783,642 $ 1,783,642 $ 1,433,626 $ 1,433,626 Equity securities 88,975 88,975 80,735 80,735 Bank loan participations 147,604 147,604 260,864 252,423 Cash and cash equivalents 162,260 162,260 206,912 206,912 Restricted cash equivalents 859,920 859,920 1,199,164 1,199,164 Short-term investments 130,289 130,289 156,925 156,925 Other invested assets – notes receivable 4,500 5,302 13,250 18,756 Liabilities Senior debt 262,300 250,953 158,300 158,043 Junior subordinated debt 104,055 110,612 104,055 122,193

Statutory Matters (Tables)

Statutory Matters (Tables)	12 Months Ended
	Dec. 31, 2020
Statutory Matters [Abstract]
Schedule of statutory accounting	Combined net income, statutory capital and surplus and minimum required statutory capital and surplus, as determined in accordance with statutory accounting practices, for the U.S. insurance subsidiaries as of December 31, 2020, 2019, and 2018 and for the years then ended are summarized as follows: 2020 2019 2018 (in thousands) Statutory net (loss) income $ (710) $ 3,586 $ 6,770 Statutory capital and surplus 286,449 266,715 241,668 Minimum required statutory capital and surplus 100,170 111,208 24,850

Accounting Policies - Narrative

Accounting Policies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)company	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)shares	Jan. 01, 2020USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Accounting Policies [Line Items]
Decrease in retained earnings	$ (795,608)	$ (778,581)	$ (709,241)			$ (694,699)
Premiums receivable and agents’ balances, net	369,577	369,462
Allowance for credit losses	8,300	5,700
Bad debt expense	3,300	2,500	1,500
Allowance for credit losses written off	660	812	313
Allowance for credit losses on reinsurance recoverables	335
Fee income	3,400	9,500	$ 13,900
Investment in variable interest entities	30,100	$ 31,200
Common share equivalents excluded from calculations of diluted earnings per share | shares		9,735	180,329
Retained Earnings
Accounting Policies [Line Items]
Decrease in retained earnings	$ (49,227)	$ (89,586)	$ (79,753)			(48,198)
Cumulative Effect, Period of Adoption, Adjustment
Accounting Policies [Line Items]
Decrease in retained earnings			(8,280)
Cumulative Effect, Period of Adoption, Adjustment | ASU 2016-13
Accounting Policies [Line Items]
Decrease in retained earnings		265
Cumulative Effect, Period of Adoption, Adjustment | ASU 2019-05
Accounting Policies [Line Items]
Fair value adjustment				$ 8,400
Decrease in retained earnings		7,827
Cumulative Effect, Period of Adoption, Adjustment | ASU 2018-02
Accounting Policies [Line Items]
Decrease in retained earnings						0
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Accounting Policies [Line Items]
Decrease in retained earnings			$ (8,280)
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings | ASU 2016-13
Accounting Policies [Line Items]
Decrease in retained earnings		265		265
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings | ASU 2019-05
Accounting Policies [Line Items]
Decrease in retained earnings		7,827		$ 7,800
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings | ASU 2018-02
Accounting Policies [Line Items]
Decrease in retained earnings					$ 711	$ 711
Minimum
Accounting Policies [Line Items]
Intangible assets, useful life (in years)	7 years
Property and equipment, estimated useful lives (in years)	3 years
Maximum
Accounting Policies [Line Items]
Intangible assets, useful life (in years)	27 years 6 months
Property and equipment, estimated useful lives (in years)	10 years
Receivables greater than 90 days past due
Accounting Policies [Line Items]
Premiums receivable and agents’ balances, net	$ 6,900	$ 3,300
United States
Accounting Policies [Line Items]
Number of insurance companies | company	5
Bermuda
Accounting Policies [Line Items]
Number of insurance companies | company	2

Accounting Policies - Schedule

Accounting Policies - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Income	$ 4,824	$ 38,339	$ 63,830
Weighted average common shares
Basic (in shares)	30,552,210	30,275,184	29,887,990
Common share equivalents (in shares)	332,206	398,740	419,111
Diluted (in shares)	30,884,416	30,673,924	30,307,101
Earnings per share
Basic earnings per share (in dollars per share)	$ 0.16	$ 1.27	$ 2.14
Common share equivalents (in dollars per share)	0	(0.02)	(0.03)
Diluted earnings per share (in dollars per share)	$ 0.16	$ 1.25	$ 2.11

Investments - Schedule of Avail

Investments - Schedule of Available-for-Sale Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	$ 1,690,890	$ 1,398,533
Gross Unrealized Gains	94,056	37,691
Gross Unrealized Losses	(1,304)	(2,598)
Fair Value	1,783,642	1,433,626
State and municipal
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	277,241	159,894
Gross Unrealized Gains	19,203	7,949
Gross Unrealized Losses	(39)	(742)
Fair Value	296,405	167,101
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	286,104	261,524
Gross Unrealized Gains	7,784	3,244
Gross Unrealized Losses	(40)	(622)
Fair Value	293,848	264,146
Corporate
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	715,145	611,304
Gross Unrealized Gains	52,098	21,306
Gross Unrealized Losses	(421)	(389)
Fair Value	766,822	632,221
Commercial mortgage and asset-backed
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	314,911	249,309
Gross Unrealized Gains	12,611	3,954
Gross Unrealized Losses	(803)	(806)
Fair Value	326,719	252,457
U.S. Treasury securities and obligations guaranteed by the U.S. government
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	97,489	114,477
Gross Unrealized Gains	2,360	1,229
Gross Unrealized Losses	(1)	(39)
Fair Value	$ 99,848	115,667
Redeemable preferred stock
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		2,025
Gross Unrealized Gains		9
Gross Unrealized Losses		0
Fair Value		$ 2,034

Investments - Schedule of Amort

Investments - Schedule of Amortized Cost and Fair Value of Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Amortized Cost
One year or less	$ 115,048
After one year through five years	457,434
After five years through ten years	283,761
After ten years	233,632
Residential mortgage-backed	286,104
Commercial mortgage and asset-backed	314,911
Cost or Amortized Cost	1,690,890	$ 1,398,533
Fair Value
One year or less	116,404
After one year through five years	485,506
After five years through ten years	306,655
After ten years	254,510
Residential mortgage-backed	293,848
Commercial mortgage and asset-backed	326,719
Total, Fair Value	$ 1,783,642	$ 1,433,626

Investments - Schedule of Gross

Investments - Schedule of Gross Unrealized Losses and Fair Values of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	$ 60,167	$ 154,118
Less Than 12 Months, Unrealized Losses	(948)	(1,612)
12 Months or More, Fair Value	38,802	111,851
12 Months or More, Gross Unrealized Losses	(356)	(986)
Total, Fair Value	98,969	265,969
Total, Gross Unrealized Losses	(1,304)	(2,598)
State and municipal
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	7,193	30,028
Less Than 12 Months, Unrealized Losses	(39)	(741)
12 Months or More, Fair Value	0	667
12 Months or More, Gross Unrealized Losses	0	(1)
Total, Fair Value	7,193	30,695
Total, Gross Unrealized Losses	(39)	(742)
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	3,649	23,632
Less Than 12 Months, Unrealized Losses	(40)	(78)
12 Months or More, Fair Value	0	37,363
12 Months or More, Gross Unrealized Losses	0	(544)
Total, Fair Value	3,649	60,995
Total, Gross Unrealized Losses	(40)	(622)
Corporate
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	28,607	45,550
Less Than 12 Months, Unrealized Losses	(421)	(365)
12 Months or More, Fair Value	0	9,933
12 Months or More, Gross Unrealized Losses	0	(24)
Total, Fair Value	28,607	55,483
Total, Gross Unrealized Losses	(421)	(389)
Commercial mortgage and asset-backed
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	18,427	46,434
Less Than 12 Months, Unrealized Losses	(447)	(406)
12 Months or More, Fair Value	38,802	56,720
12 Months or More, Gross Unrealized Losses	(356)	(400)
Total, Fair Value	57,229	103,154
Total, Gross Unrealized Losses	(803)	(806)
U.S. Treasury securities and obligations guaranteed by the U.S. government
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	2,291	8,474
Less Than 12 Months, Unrealized Losses	(1)	(22)
12 Months or More, Fair Value	0	7,168
12 Months or More, Gross Unrealized Losses	0	(17)
Total, Fair Value	2,291	15,642
Total, Gross Unrealized Losses	$ (1)	$ (39)

Investments - Narrative (Detail

Investments - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)issuer	Dec. 31, 2019USD ($)loanissuer	Dec. 31, 2018USD ($)	Jan. 01, 2020USD ($)	Dec. 31, 2017USD ($)
Debt Securities, Available-for-sale [Line Items]
Number of available-for-sale securities held in an unrealized loss position | issuer	67
Total fair value of unrealized loss position securities	$ 98,969	$ 265,969
Gross unrealized losses	1,304	2,598
Shareholders' equity	795,608	778,581	$ 709,241		$ 694,699
Bank loan portfolio aggregated unpaid principal balance	159,600
Bank loan portfolio aggregate fair value	147,604
Changes in fair values of bank loan participations	1,318	0	0
Losses due to credit-related impairments	8,300
Carrying value of impaired loans		6,900
Unpaid principal on impaired loans		14,300
Allowance for credit losses		7,200
Net Investment Income	73,368	75,652	61,256
Fixed maturity securities, available-for-sale	1,783,642	1,433,626
Investment as collateral for outstanding letters of credit	463,400
Investments on deposit with state insurance departments	46,900	36,600
Retained Earnings
Debt Securities, Available-for-sale [Line Items]
Shareholders' equity	$ 49,227	89,586	79,753		$ 48,198
Cumulative Effect, Period of Adoption, Adjustment
Debt Securities, Available-for-sale [Line Items]
Shareholders' equity			8,280
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Debt Securities, Available-for-sale [Line Items]
Shareholders' equity			8,280
Cumulative Effect, Period of Adoption, Adjustment | ASU 2019-05
Debt Securities, Available-for-sale [Line Items]
Bank loan participations				$ (8,400)
Shareholders' equity		(7,827)
Cumulative Effect, Period of Adoption, Adjustment | ASU 2019-05 | Retained Earnings
Debt Securities, Available-for-sale [Line Items]
Shareholders' equity		(7,827)		(7,800)
Cumulative Effect, Period of Adoption, Adjustment | ASU 2016-13
Debt Securities, Available-for-sale [Line Items]
Shareholders' equity		(265)
Cumulative Effect, Period of Adoption, Adjustment | ASU 2016-13 | Retained Earnings
Debt Securities, Available-for-sale [Line Items]
Shareholders' equity		$ (265)		$ (265)
Impaired bank loans
Debt Securities, Available-for-sale [Line Items]
Number of impaired loans | loan		7
Number of issuers with impaired loans | issuer		6
Average recorded investment in impaired bank loans		$ 3,500	2,600
Net Investment Income		293	125
Net realized gain (loss) on changes in fair value of impaired bank loans		$ (8,900)	$ (858)
Loans from issuer experiencing liquidity concerns
Debt Securities, Available-for-sale [Line Items]
Number of impaired loans | loan		2
Number of issuers with impaired loans | issuer		1
Allowance for credit losses		$ 5,100
Bank loan participations
Debt Securities, Available-for-sale [Line Items]
Unamortized discount		2,400
Unamortized premium		4
Standard & Poor's, BBB- or better Rating | Available-for-sale fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Percentage of available for sale securities	99.60%
Loan Participations and Assignments
Debt Securities, Available-for-sale [Line Items]
Net Investment Income	$ 12,200
Bank Holding Company
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	$ 520	$ 3,200

Investments - Summary of Net In

Investments - Summary of Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Investment Income [Line Items]
Gross investment income	$ 77,820	$ 80,373	$ 65,490
Investment expense	(4,452)	(4,721)	(4,234)
Net investment income	73,368	75,652	61,256
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	45,070	39,875	34,129
Bank loan participations
Net Investment Income [Line Items]
Gross investment income	12,150	19,772	18,279
Equity securities
Net Investment Income [Line Items]
Gross investment income	4,800	5,262	5,240
Other invested assets
Net Investment Income [Line Items]
Gross investment income	9,181	6,254	5,165
Cash, cash equivalents, restricted cash equivalents, and short-term investments
Net Investment Income [Line Items]
Gross investment income	$ 6,619	$ 9,210	$ 2,677

Investments - Summary of Realiz

Investments - Summary of Realized Gains and Losses on Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Fixed maturity securities, gross realized gains	$ 1,098	$ 1,575	$ 422
Fixed maturity securities, gross realized losses	(53)	(494)	(976)
Fixed maturity securities	1,045	1,081	(554)
Equity securities, gross realized gains	0	11	0
Equity securities, gross realized losses	(1,441)	(232)	(62)
Changes in fair values of equity securities	(215)	6,257	(5,970)
Equity securities	(1,656)	6,036	(6,032)
Bank loan participations, gross realized gain	554	846	2,279
Bank loan participations, gross realized losses	(17,286)	(10,902)	(1,166)
Changes in fair values of bank loan participations	1,318	0	0
Bank loan participations	(15,414)	(10,056)	1,113
Short-term investments and other, gross realized gains	77	21	0
Short-term investments and other, gross realized losses	(2)	(1)	(6)
Changes in fair values of short-term investments and other	(80)	0	0
Short-term investments and other	(5)	20	(6)
Total	$ (16,030)	$ (2,919)	$ (5,479)

Investments - Summary of Availa

Investments - Summary of Available-for-Sale Gross Unrealized Gains or Losses by Investment Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, change in gross unrealized gains (losses)	$ 57,659	$ 50,300	$ (22,643)
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, change in gross unrealized gains (losses)	$ 57,659	$ 50,300	$ (22,643)

Investments - Summary of Privat

Investments - Summary of Private Debt and Equity Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Investment Income [Line Items]
Total other invested assets	$ 46,548	$ 61,210
Investment income	9,181	6,254	$ 5,165
Distributions from equity method investments	3,162	2,834	7,499
Equity in net income of subsidiaries	3,208	4,598	3,540
Renewable energy LLCs
Net Investment Income [Line Items]
Total other invested assets	30,145	31,219
Investment income	2,016	2,181	2,974
Renewable energy notes receivable
Net Investment Income [Line Items]
Total other invested assets	0	8,750
Investment income	5,630	1,313	1,282
Total principal balance received	8,800
Gain at maturity	$ 5,300
Investment interest rate	15.00%
Interest income	$ 5,600	1,300	1,300
Limited partnerships
Net Investment Income [Line Items]
Total other invested assets	11,903	16,741
Investment income	1,192	2,417	566
Bank holding companies
Net Investment Income [Line Items]
Total other invested assets	4,500	4,500
Investment income	343	343	343
Corporate and other segment | Limited partnerships
Net Investment Income [Line Items]
Carrying value of investments	7,800	3,400
Equity in net income of subsidiaries	1,300	327	70
Excess and Surplus Lines | Limited partnerships
Net Investment Income [Line Items]
Carrying value of investments	4,100	13,300
Equity in net income of subsidiaries	(69)	2,100	$ 496
Commitment to investment in limited partnership	3,700
Excess and Surplus Lines | Limited partnerships | Newly acquired limited partnership
Net Investment Income [Line Items]
Commitment to investment in limited partnership	5,000
Investment in LLC | Corporate and other segment
Net Investment Income [Line Items]
Distributions from equity method investments	$ 3,100	$ 757
Bank Holding Company
Net Investment Income [Line Items]
Investment interest rate	7.60%
Interest income	$ 343
Bank Holding Company | Corporate and other segment
Net Investment Income [Line Items]
Investment in private subordinated notes	$ 4,500
Minimum | Investment in LLC | Corporate and other segment
Net Investment Income [Line Items]
Ownership percentage	2.60%
Maximum | Investment in LLC | Corporate and other segment
Net Investment Income [Line Items]
Ownership percentage	32.60%

Deferred Policy Acquisition C_3

Deferred Policy Acquisition Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance at beginning of period	$ 62,006	$ 54,450	$ 72,365
Policy acquisition costs deferred:
Commissions	51,306	67,303	72,473
Underwriting and other issue expenses	25,219	24,146	20,715
Policy acquisition costs deferred	76,525	91,449	93,188
Amortization of policy acquisition costs	(75,578)	(83,893)	(111,103)
Net change	947	7,556	(17,915)
Balance at end of period	$ 62,953	$ 62,006	$ 54,450

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 11, 2007
Business Acquisition [Line Items]
Goodwill impairment	$ 0	$ 0	$ 0
Goodwill	181,831,000	181,831,000	181,831,000
Accumulated goodwill impairment losses	99,600,000	99,600,000
Identifiable intangibles not subject to amortization	31,164,000	31,164,000
Impairment of intangible assets	0	0	200,000
Amortization of intangible assets	538,000	597,000	597,000
Excess and Surplus Lines
Business Acquisition [Line Items]
Goodwill	181,831,000	181,831,000	181,831,000
Amortization of intangible assets	366,000	362,000	362,000
Specialty Admitted Insurance
Business Acquisition [Line Items]
Goodwill	0	0	0
Impairment of intangible assets			200,000
Amortization of intangible assets	$ 172,000	$ 235,000	235,000
James River Group, Inc.
Business Acquisition [Line Items]
Percentage of outstanding shares acquired				100.00%
State Licenses
Business Acquisition [Line Items]
Identifiable intangibles not subject to amortization			$ 0

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Acquired Intangible Assets [Line Items]
Identifiable intangibles not subject to amortization	$ 31,164	$ 31,164
Identifiable intangible assets subject to amortization
Gross Carrying Amount	11,611	11,611
Accumulated Amortization	6,373	5,835
Total intangible assets, gross	42,775	42,775
Broker relationships
Identifiable intangible assets subject to amortization
Gross Carrying Amount	11,611	11,611
Accumulated Amortization	$ 6,373	5,835
Weighted-Average Life (in years)	24 years 7 months 6 days
Trademarks
Acquired Intangible Assets [Line Items]
Identifiable intangibles not subject to amortization	$ 22,200	22,200
Insurance licenses and authorities
Acquired Intangible Assets [Line Items]
Identifiable intangibles not subject to amortization	$ 8,964	$ 8,964

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Schedule of Future Estimated Amortization (Details) $ in Thousands	Dec. 31, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 363
2022	363
2023	363
2024	363
2025	363
Thereafter	3,423
Total	$ 5,238

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Summary of Changes in Net Carrying Value of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets [Roll Forward]
Net Carrying Value	$ 36,940	$ 37,537
Amortization	(538)	(597)	$ (597)
Impairment Losses	0	0	(200)
Net Carrying Value	36,402	36,940	37,537
Excess and Surplus Lines
Intangible Assets [Roll Forward]
Net Carrying Value	30,203	30,565
Amortization	(366)	(362)	(362)
Impairment Losses	0	0
Net Carrying Value	29,837	30,203	30,565
Excess and Surplus Lines | Trademarks
Intangible Assets [Roll Forward]
Net Carrying Value	19,700	19,700
Amortization	0	0
Impairment Losses	0	0
Net Carrying Value	19,700	19,700	19,700
Excess and Surplus Lines | Insurance licenses and authorities
Intangible Assets [Roll Forward]
Net Carrying Value	4,900	4,900
Amortization	0	0
Impairment Losses	0	0
Net Carrying Value	4,900	4,900	4,900
Excess and Surplus Lines | Broker relationships
Intangible Assets [Roll Forward]
Net Carrying Value	5,603	5,965
Amortization	(366)	(362)
Impairment Losses	0	0
Net Carrying Value	5,237	5,603	5,965
Specialty Admitted Insurance
Intangible Assets [Roll Forward]
Net Carrying Value	6,737	6,972
Amortization	(172)	(235)	(235)
Impairment Losses	0	0
Net Carrying Value	6,565	6,737	6,972
Specialty Admitted Insurance | Trademarks
Intangible Assets [Roll Forward]
Net Carrying Value	2,500	2,500
Amortization	0	0
Impairment Losses	0	0
Net Carrying Value	2,500	2,500	2,500
Specialty Admitted Insurance | Insurance licenses and authorities
Intangible Assets [Roll Forward]
Net Carrying Value	4,065	4,065
Amortization	0	0
Impairment Losses	0	0
Net Carrying Value	4,065	4,065	4,065
Specialty Admitted Insurance | Broker relationships
Intangible Assets [Roll Forward]
Net Carrying Value	172	407
Amortization	(172)	(235)
Impairment Losses	0	0
Net Carrying Value	$ 0	$ 172	$ 407

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, cost basis	$ 5,263	$ 9,187
Accumulated depreciation	(3,975)	(7,419)
Property and equipment, net	1,288	1,768
Electronic data processing hardware and software
Property, Plant and Equipment [Line Items]
Property and equipment, cost basis	3,238	7,007
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, cost basis	$ 2,025	$ 2,180

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019	Dec. 31, 2017
Related Party Transaction [Line Items]
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Assets	$ (5,063,072)	$ (5,024,405)	$ (3,136,776)
Liabilities	(4,267,464)	(4,245,824)
Shareholders' equity	795,608	778,581	709,241		$ 694,699
Lease liabilities	14,916	18,200
Right-of-use assets	$ 14,000	17,200
Weighted average discount rate	4.30%
Weighted average remaining lease term	4 years 4 months 24 days
Operating lease costs	$ 5,000	$ 5,200	4,600
ASU 2016-02
Related Party Transaction [Line Items]
Assets				$ 22,600
Liabilities				30,900
Lease liabilities				17,800
Right-of-use assets				17,200
Cumulative Effect, Period of Adoption, Adjustment
Related Party Transaction [Line Items]
Shareholders' equity			$ 8,280
Cumulative Effect, Period of Adoption, Adjustment | ASU 2016-02
Related Party Transaction [Line Items]
Shareholders' equity				$ 8,300
Minority interest in partnership
Related Party Transaction [Line Items]
Lease liabilities	$ 10,300

Leases - Summary of Operating L

Leases - Summary of Operating Lease Liabilities Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
2021	$ 3,993
2022	3,800
2023	3,619
2024	2,422
2025	2,349
Thereafter	197
Total lease payments	16,380
Less imputed interest	(1,464)
Total operating lease liabilities	$ 14,916	$ 18,200

Reserve for Losses and Loss A_3

Reserve for Losses and Loss Adjustment Expenses - Reserve for Losses and Loss Adjustment Expenses, Net of Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Unpaid Claims and Claims Adjustment Expense, Period Increase (Decrease) [Abstract]
Reserve for losses and loss adjustment expenses net of reinsurance recoverables at beginning of period	$ 1,377,461	$ 1,194,088	$ 989,825
Add: Incurred losses and loss adjustment expenses net of reinsurance:
Current year	386,341	603,094	582,604
Prior years	92,204	69,008	17,672
Total incurred losses and loss and adjustment expenses	478,545	672,102	600,276
Deduct: Loss and loss adjustment expense payments net of reinsurance:
Current year	31,952	75,249	86,355
Prior years	437,993	413,480	309,658
Total loss and loss adjustment expense payments	469,945	488,729	396,013
Reserve for losses and loss adjustment expenses net of reinsurance recoverables at end of period	1,386,061	1,377,461	1,194,088
Add: Reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period	806,019	668,045	467,371
Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period	$ 2,192,080	$ 2,045,506	$ 1,661,459

Reserve for Losses and Loss A_4

Reserve for Losses and Loss Adjustment Expenses - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses	$ (92,204)	$ (69,008)	$ (17,672)
Excess and Surplus Lines
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses	(59,400)	(51,200)	(15,000)
Specialty Admitted Insurance | Accident years prior to 2018
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses		5,300
Specialty Admitted Insurance | Accident years 2014 through 2016
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses			5,600
Specialty Admitted Insurance | Accident years prior to 2019
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses	5,000
Casualty Reinsurance | Accident years 2011 through 2016
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses		(23,100)
Casualty Reinsurance | Accident years at least four years old
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses			(8,200)
Casualty Reinsurance | Accident years 2014 through 2018
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses	(37,800)
Excluding Commercial Auto | Excess and Surplus Lines
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses		6,200
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2017
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses			5,700
Excluding Commercial Auto | Excess and Surplus Lines | Accident years 2018 and 2019
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses	32,000
Commercial Auto | Excess and Surplus Lines | Accident years 2016 and 2017
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses		$ (57,400)
Commercial Auto | Excess and Surplus Lines | Accident year 2016
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses			$ (20,700)
Commercial Auto | Excess and Surplus Lines | Accident years 2018 and prior
Favorable development on prior year loss reserves
Reserves for losses and loss adjustment expenses	$ (91,400)

Reserve for Losses and Loss A_5

Reserve for Losses and Loss Adjustment Expenses - Incurred Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Casualty Reinsurance
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	$ 1,199,776
Cumulative paid losses and loss adjustment expenses, net of reinsurance	896,160
All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance	4,198
Total outstanding losses and loss adjustment expenses, net of reinsurance	307,814
Casualty Reinsurance | Accident year 2011
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	106,226	$ 105,333	$ 103,196	$ 101,276	$ 99,282	$ 98,993	$ 97,812	$ 97,366	$ 103,123	$ 114,908
Cumulative paid losses and loss adjustment expenses, net of reinsurance	101,209	99,511	97,715	94,627	90,287	87,267	78,164	68,616	61,922	48,688
Casualty Reinsurance | Accident year 2012
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	147,413	146,045	143,305	139,978	136,813	135,594	131,281	132,388	148,251
Cumulative paid losses and loss adjustment expenses, net of reinsurance	139,719	137,430	133,606	128,567	121,026	113,943	97,215	81,859	73,124
Casualty Reinsurance | Accident year 2013
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	149,682	146,760	143,124	137,801	134,446	131,352	130,361	133,230
Cumulative paid losses and loss adjustment expenses, net of reinsurance	139,250	134,644	127,732	119,256	108,396	93,902	75,094	59,756
Casualty Reinsurance | Accident year 2014
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	130,822	126,160	121,200	116,981	114,636	115,927	118,881
Cumulative paid losses and loss adjustment expenses, net of reinsurance	117,971	110,374	101,366	89,899	76,302	58,601	41,421
Casualty Reinsurance | Accident year 2015
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	120,185	114,517	109,117	108,699	108,870	119,157
Cumulative paid losses and loss adjustment expenses, net of reinsurance	100,548	90,661	80,208	68,002	53,986	40,021
Casualty Reinsurance | Accident year 2016
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	114,979	108,222	103,544	105,533	112,759
Cumulative paid losses and loss adjustment expenses, net of reinsurance	90,356	78,145	65,409	50,905	36,268
Casualty Reinsurance | Accident year 2017
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	138,831	129,800	128,472	134,628
Cumulative paid losses and loss adjustment expenses, net of reinsurance	106,942	90,117	72,891	47,739
Casualty Reinsurance | Accident year 2018
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	125,715	119,098	121,529
Cumulative paid losses and loss adjustment expenses, net of reinsurance	69,123	50,274	30,903
Casualty Reinsurance | Accident year 2019
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	85,549	86,022
Cumulative paid losses and loss adjustment expenses, net of reinsurance	25,453	12,646
Casualty Reinsurance | Accident year 2020
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	80,374
Cumulative paid losses and loss adjustment expenses, net of reinsurance	5,589
Commercial Auto | Excess and Surplus Lines
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	1,078,810
Cumulative paid losses and loss adjustment expenses, net of reinsurance	741,769
Total outstanding losses and loss adjustment expenses, net of reinsurance	337,041
Commercial Auto | Excess and Surplus Lines | Accident year 2013
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	1,277	1,277	1,277	1,301	1,351	1,451	1,300	1,255
Cumulative paid losses and loss adjustment expenses, net of reinsurance	1,275	1,275	1,275	1,275	1,291	1,285	1,182	60
Commercial Auto | Excess and Surplus Lines | Accident year 2014
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	19,196	18,303	19,779	18,953	17,233	14,071	20,487
Cumulative paid losses and loss adjustment expenses, net of reinsurance	18,301	17,745	18,678	16,359	12,679	8,645	6,166
Commercial Auto | Excess and Surplus Lines | Accident year 2015
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	37,839	36,636	36,139	35,149	33,113	30,109
Cumulative paid losses and loss adjustment expenses, net of reinsurance	35,983	34,819	31,592	24,282	15,234	8,356
Commercial Auto | Excess and Surplus Lines | Accident year 2016
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	157,712	147,122	126,791	109,286	74,340
Cumulative paid losses and loss adjustment expenses, net of reinsurance	141,545	125,108	89,381	54,054	18,295
Commercial Auto | Excess and Surplus Lines | Accident year 2017
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	319,472	272,421	208,743	207,355
Cumulative paid losses and loss adjustment expenses, net of reinsurance	252,169	192,961	107,377	41,467
Commercial Auto | Excess and Surplus Lines | Accident year 2018
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	283,408	230,220	255,881
Cumulative paid losses and loss adjustment expenses, net of reinsurance	184,686	119,099	45,136
Commercial Auto | Excess and Surplus Lines | Accident year 2019
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	240,773	262,306
Cumulative paid losses and loss adjustment expenses, net of reinsurance	107,182	44,225
Commercial Auto | Excess and Surplus Lines | Accident year 2020
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	19,133
Cumulative paid losses and loss adjustment expenses, net of reinsurance	628
Excluding Commercial Auto | Excess and Surplus Lines
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	1,324,223
Cumulative paid losses and loss adjustment expenses, net of reinsurance	685,856
All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance	7,946
Total outstanding losses and loss adjustment expenses, net of reinsurance	646,313
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2011
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	104,280	105,173	106,536	106,643	106,130	106,381	106,564	114,473	119,927	111,190
Cumulative paid losses and loss adjustment expenses, net of reinsurance	101,969	101,728	99,798	98,684	94,998	90,884	81,696	72,732	53,109	27,684
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2012
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	106,118	103,061	101,271	99,619	97,306	96,497	97,829	98,672	97,908
Cumulative paid losses and loss adjustment expenses, net of reinsurance	99,628	94,588	88,812	82,545	74,869	63,216	49,604	33,757	6,944
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2013
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	82,517	82,732	83,855	82,830	81,009	85,433	96,064	96,729
Cumulative paid losses and loss adjustment expenses, net of reinsurance	74,635	71,035	66,553	59,641	44,421	30,382	14,509	3,867
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2014
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	90,191	88,904	84,074	82,232	90,267	104,092	114,942
Cumulative paid losses and loss adjustment expenses, net of reinsurance	76,523	71,549	58,774	43,891	28,212	16,969	3,412
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2015
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	110,466	103,688	102,434	104,847	113,417	126,443
Cumulative paid losses and loss adjustment expenses, net of reinsurance	87,344	73,455	55,911	34,801	17,164	4,048
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2016
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	125,097	126,971	126,050	125,093	138,507
Cumulative paid losses and loss adjustment expenses, net of reinsurance	90,166	70,105	46,045	22,852	5,180
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2017
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	124,265	132,136	131,897	144,349
Cumulative paid losses and loss adjustment expenses, net of reinsurance	64,924	42,764	22,956	5,290
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2018
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	146,633	158,458	167,004
Cumulative paid losses and loss adjustment expenses, net of reinsurance	50,679	26,160	6,000
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2019
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	194,759	214,653
Cumulative paid losses and loss adjustment expenses, net of reinsurance	31,346	8,235
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2020
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	239,897
Cumulative paid losses and loss adjustment expenses, net of reinsurance	8,642
Fronting and Programs | Specialty Admitted Insurance
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	115,048
Cumulative paid losses and loss adjustment expenses, net of reinsurance	58,368
All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance	56,680
Total outstanding losses and loss adjustment expenses, net of reinsurance	57,281
Fronting and Programs | Specialty Admitted Insurance | Accident year 2013
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	52	52	52	52	52	52	80	104
Cumulative paid losses and loss adjustment expenses, net of reinsurance	52	52	52	52	52	52	52	28
Fronting and Programs | Specialty Admitted Insurance | Accident year 2014
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	3,081	3,083	3,228	3,425	3,818	3,468	3,460
Cumulative paid losses and loss adjustment expenses, net of reinsurance	2,917	2,916	2,854	2,728	2,369	1,687	883
Fronting and Programs | Specialty Admitted Insurance | Accident year 2015
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	8,444	8,384	8,974	9,358	9,632	7,136
Cumulative paid losses and loss adjustment expenses, net of reinsurance	7,654	7,329	6,919	6,165	4,666	2,058
Fronting and Programs | Specialty Admitted Insurance | Accident year 2016
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	14,468	15,522	14,682	15,670	11,542
Cumulative paid losses and loss adjustment expenses, net of reinsurance	10,896	10,732	6,888	5,123	1,894
Fronting and Programs | Specialty Admitted Insurance | Accident year 2017
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	24,728	25,201	24,271	21,229
Cumulative paid losses and loss adjustment expenses, net of reinsurance	15,854	13,065	6,682	1,223
Fronting and Programs | Specialty Admitted Insurance | Accident year 2018
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	19,822	20,677	21,758
Cumulative paid losses and loss adjustment expenses, net of reinsurance	10,495	4,972	885
Fronting and Programs | Specialty Admitted Insurance | Accident year 2019
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	19,020	18,832
Cumulative paid losses and loss adjustment expenses, net of reinsurance	5,125	4,358
Fronting and Programs | Specialty Admitted Insurance | Accident year 2020
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	25,433
Cumulative paid losses and loss adjustment expenses, net of reinsurance	5,375
Individual Risk Workers' Compensation | Specialty Admitted Insurance
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	192,747
Cumulative paid losses and loss adjustment expenses, net of reinsurance	160,730
All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance	1,237
Total outstanding losses and loss adjustment expenses, net of reinsurance	37,612
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2011
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	35,252	36,593	36,593	36,594	37,455	38,311	38,999	40,154	41,421	37,834
Cumulative paid losses and loss adjustment expenses, net of reinsurance	34,665	34,638	34,614	34,334	34,287	34,240	33,204	29,021	23,127	$ 10,123
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2012
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	27,741	28,186	28,186	28,174	28,255	29,689	31,490	32,420	32,116
Cumulative paid losses and loss adjustment expenses, net of reinsurance	27,128	26,994	26,963	26,932	26,897	26,435	24,755	20,308	$ 9,222
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2013
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	10,598	10,909	10,909	10,907	11,578	12,786	13,668	12,525
Cumulative paid losses and loss adjustment expenses, net of reinsurance	10,335	10,337	10,309	10,263	10,246	9,846	8,723	$ 4,487
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2014
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	12,573	12,704	12,704	13,890	14,620	16,652	16,638
Cumulative paid losses and loss adjustment expenses, net of reinsurance	12,276	12,282	12,282	12,236	12,041	10,648	$ 4,633
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2015
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	16,492	17,626	18,376	19,741	21,274	20,938
Cumulative paid losses and loss adjustment expenses, net of reinsurance	16,068	15,901	15,889	15,118	13,285	$ 6,604
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2016
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	14,050	15,800	18,050	20,299	21,678
Cumulative paid losses and loss adjustment expenses, net of reinsurance	12,481	12,432	12,135	10,227	$ 4,664
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2017
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	18,810	19,779	22,071	24,869
Cumulative paid losses and loss adjustment expenses, net of reinsurance	15,195	14,285	12,782	$ 6,546
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2018
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	16,038	16,288	16,432
Cumulative paid losses and loss adjustment expenses, net of reinsurance	11,412	9,034	$ 4,497
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2019
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	21,056	20,253
Cumulative paid losses and loss adjustment expenses, net of reinsurance	13,776	$ 5,473
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2020
Claims Development [Line Items]
Incurred losses and loss adjustment expenses, net of reinsurance	20,137
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 7,394

Reserve for Losses and Loss A_6

Reserve for Losses and Loss Adjustment Expenses - Cumulative Paid Losses and Loss Adjustment Expenses (Details) $ in Thousands	Dec. 31, 2020USD ($)Claimclaim	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)
Casualty Reinsurance
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 896,160
All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance	4,198
Total outstanding losses and loss adjustment expenses, net of reinsurance	307,814
Casualty Reinsurance | Accident year 2011
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	101,209	$ 99,511	$ 97,715	$ 94,627	$ 90,287	$ 87,267	$ 78,164	$ 68,616	$ 61,922	$ 48,688
Casualty Reinsurance | Accident year 2012
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	139,719	137,430	133,606	128,567	121,026	113,943	97,215	81,859	73,124
Casualty Reinsurance | Accident year 2013
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	139,250	134,644	127,732	119,256	108,396	93,902	75,094	59,756
Casualty Reinsurance | Accident year 2014
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	117,971	110,374	101,366	89,899	76,302	58,601	41,421
Casualty Reinsurance | Accident year 2015
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	100,548	90,661	80,208	68,002	53,986	40,021
Casualty Reinsurance | Accident year 2016
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	90,356	78,145	65,409	50,905	36,268
Casualty Reinsurance | Accident year 2017
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	106,942	90,117	72,891	47,739
Casualty Reinsurance | Accident year 2018
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	69,123	50,274	30,903
Casualty Reinsurance | Accident year 2019
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	25,453	12,646
Casualty Reinsurance | Accident year 2020
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	5,589
Excluding Commercial Auto | Excess and Surplus Lines
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	685,856
All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance	7,946
Total outstanding losses and loss adjustment expenses, net of reinsurance	$ 646,313
Claims outstanding | claim	46
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2011
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 101,969	101,728	99,798	98,684	94,998	90,884	81,696	72,732	53,109	27,684
Claims outstanding | Claim	1,488
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2012
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 99,628	94,588	88,812	82,545	74,869	63,216	49,604	33,757	6,944
Claims outstanding | Claim	1,850
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2013
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 74,635	71,035	66,553	59,641	44,421	30,382	14,509	3,867
Claims outstanding | Claim	2,480
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2014
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 76,523	71,549	58,774	43,891	28,212	16,969	3,412
Claims outstanding | Claim	2,198
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2015
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 87,344	73,455	55,911	34,801	17,164	4,048
Claims outstanding | Claim	2,587
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2016
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 90,166	70,105	46,045	22,852	5,180
Claims outstanding | Claim	3,023
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2017
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 64,924	42,764	22,956	5,290
Claims outstanding | Claim	3,085
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2018
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 50,679	26,160	6,000
Claims outstanding | Claim	4,267
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2019
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 31,346	8,235
Claims outstanding | Claim	4,950
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2020
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 8,642
Claims outstanding | Claim	3,115
Fronting and Programs | Specialty Admitted Insurance
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 58,368
All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance	56,680
Outstanding losses and loss adjustment expenses assumed from involuntary workers compensation pools	601
Total outstanding losses and loss adjustment expenses, net of reinsurance	57,281
Fronting and Programs | Specialty Admitted Insurance | Accident year 2013
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 52	52	52	52	52	52	52	28
Claims outstanding | Claim	22
Fronting and Programs | Specialty Admitted Insurance | Accident year 2014
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 2,917	2,916	2,854	2,728	2,369	1,687	883
Claims outstanding | Claim	858
Fronting and Programs | Specialty Admitted Insurance | Accident year 2015
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 7,654	7,329	6,919	6,165	4,666	2,058
Claims outstanding | Claim	1,363
Fronting and Programs | Specialty Admitted Insurance | Accident year 2016
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 10,896	10,732	6,888	5,123	1,894
Claims outstanding | Claim	2,815
Fronting and Programs | Specialty Admitted Insurance | Accident year 2017
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 15,854	13,065	6,682	1,223
Claims outstanding | Claim	6,765
Fronting and Programs | Specialty Admitted Insurance | Accident year 2018
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 10,495	4,972	885
Claims outstanding | Claim	7,318
Fronting and Programs | Specialty Admitted Insurance | Accident year 2019
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 5,125	4,358
Claims outstanding | Claim	7,941
Fronting and Programs | Specialty Admitted Insurance | Accident year 2020
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 5,375
Claims outstanding | Claim	6,956
Individual Risk Workers' Compensation | Specialty Admitted Insurance
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 160,730
All outstanding losses and loss adjustment expenses prior to 2011, net of reinsurance	1,237
Outstanding losses and loss adjustment expenses assumed from involuntary workers compensation pools	4,358
Total outstanding losses and loss adjustment expenses, net of reinsurance	$ 37,612
Claims outstanding | claim	4
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2011
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 34,665	34,638	34,614	34,334	34,287	34,240	33,204	29,021	23,127	$ 10,123
Claims outstanding | Claim	1,814
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2012
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 27,128	26,994	26,963	26,932	26,897	26,435	24,755	20,308	$ 9,222
Claims outstanding | Claim	1,323
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2013
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 10,335	10,337	10,309	10,263	10,246	9,846	8,723	4,487
Claims outstanding | Claim	540
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2014
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 12,276	12,282	12,282	12,236	12,041	10,648	4,633
Claims outstanding | Claim	850
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2015
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 16,068	15,901	15,889	15,118	13,285	6,604
Claims outstanding | Claim	975
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2016
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 12,481	12,432	12,135	10,227	4,664
Claims outstanding | Claim	836
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2017
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 15,195	14,285	12,782	6,546
Claims outstanding | Claim	1,093
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2018
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 11,412	9,034	4,497
Claims outstanding | Claim	1,238
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2019
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 13,776	5,473
Claims outstanding | Claim	1,548
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2020
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 7,394
Claims outstanding | Claim	1,305
Commercial Auto | Excess and Surplus Lines
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 741,769
Total outstanding losses and loss adjustment expenses, net of reinsurance	337,041
Commercial Auto | Excess and Surplus Lines | Accident year 2013
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 1,275	1,275	1,275	1,275	1,291	1,285	1,182	$ 60
Claims outstanding | Claim	54
Commercial Auto | Excess and Surplus Lines | Accident year 2014
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 18,301	17,745	18,678	16,359	12,679	8,645	$ 6,166
Claims outstanding | Claim	7,764
Commercial Auto | Excess and Surplus Lines | Accident year 2015
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 35,983	34,819	31,592	24,282	15,234	$ 8,356
Claims outstanding | Claim	41,766
Commercial Auto | Excess and Surplus Lines | Accident year 2016
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 141,545	125,108	89,381	54,054	$ 18,295
Claims outstanding | Claim	89,084
Commercial Auto | Excess and Surplus Lines | Accident year 2017
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 252,169	192,961	107,377	$ 41,467
Claims outstanding | Claim	134,055
Commercial Auto | Excess and Surplus Lines | Accident year 2018
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 184,686	119,099	$ 45,136
Claims outstanding | Claim	97,076
Commercial Auto | Excess and Surplus Lines | Accident year 2019
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 107,182	$ 44,225
Claims outstanding | Claim	70,707
Commercial Auto | Excess and Surplus Lines | Accident year 2020
Claims Development [Line Items]
Cumulative paid losses and loss adjustment expenses, net of reinsurance	$ 628
Claims outstanding | Claim	498

Reserve for Losses and Loss A_7

Reserve for Losses and Loss Adjustment Expenses - Reserves for Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Claims Development [Line Items]
Net reserve for losses and loss adjustment expenses	$ 1,386,061	$ 1,377,461	$ 1,194,088	$ 989,825
Allowance for credit losses on reinsurance recoverables	335
Reinsurance recoverables on unpaid losses (gross of $335,000 allowance for credit losses on reinsurance recoverables)	806,019	668,045	467,371
Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period	2,192,080	$ 2,045,506	$ 1,661,459
Casualty Reinsurance
Claims Development [Line Items]
Net reserve for losses and loss adjustment expenses	307,814
Fronting and Programs | Specialty Admitted Insurance
Claims Development [Line Items]
Net reserve for losses and loss adjustment expenses	57,281
Excluding Commercial Auto | Excess and Surplus Lines
Claims Development [Line Items]
Net reserve for losses and loss adjustment expenses	646,313
Commercial Auto | Excess and Surplus Lines
Claims Development [Line Items]
Net reserve for losses and loss adjustment expenses	337,041
Individual Risk Workers' Compensation | Specialty Admitted Insurance
Claims Development [Line Items]
Net reserve for losses and loss adjustment expenses	$ 37,612

Reserve for Losses and Loss A_8

Reserve for Losses and Loss Adjustment Expenses - Average Annual Percentage Payouts of Incurred Claims (Details)	Dec. 31, 2020
Casualty Reinsurance
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	22.10%
Year 2	15.90%
Year 3	11.60%
Year 4	8.50%
Year 5	6.60%
Year 6	5.20%
Year 7	4.10%
Year 8	3.50%
Year 9	3.40%
Year 10	2.90%
Fronting and Programs | Specialty Admitted Insurance
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	17.40%
Year 2	20.50%
Year 3	25.40%
Year 4	14.70%
Year 5	9.80%
Year 6	7.30%
Year 7	2.20%
Year 8	2.60%
Excluding Commercial Auto | E&S
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	9.00%
Year 2	15.40%
Year 3	17.20%
Year 4	18.30%
Year 5	15.00%
Year 6	7.90%
Year 7	5.40%
Year 8	4.00%
Year 9	2.20%
Year 10	1.80%
Commercial Auto | E&S
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	18.20%
Year 2	38.30%
Year 3	16.40%
Year 4	13.70%
Year 5	7.70%
Year 6	3.00%
Year 7	0.30%
Year 8	2.30%
Individual Risk Workers' Compensation | Specialty Admitted Insurance
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	27.10%
Year 2	31.60%
Year 3	15.30%
Year 4	9.00%
Year 5	6.30%
Year 6	3.40%
Year 7	2.20%
Year 8	1.20%
Year 9	1.20%
Year 10	0.80%

Reserve for Losses and Loss A_9

Reserve for Losses and Loss Adjustment Expenses - IBNR Liabilities and Claims Frequency (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)Claimclaim	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 478,545	$ 672,102	$ 600,276
Casualty Reinsurance | Accident year 2011
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	106,226
IBNR	819
Casualty Reinsurance | Accident year 2012
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	147,413
IBNR	1,566
Casualty Reinsurance | Accident year 2013
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	149,682
IBNR	2,427
Casualty Reinsurance | Accident year 2014
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	130,822
IBNR	3,200
Casualty Reinsurance | Accident year 2015
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	120,185
IBNR	5,147
Casualty Reinsurance | Accident year 2016
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	114,979
IBNR	9,091
Casualty Reinsurance | Accident year 2017
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	138,831
IBNR	17,173
Casualty Reinsurance | Accident year 2018
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	125,715
IBNR	31,058
Casualty Reinsurance | Accident year 2019
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	85,549
IBNR	49,717
Casualty Reinsurance | Accident year 2020
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	80,374
IBNR	61,595
Fronting and Programs | Specialty Admitted Insurance | Accident year 2013
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	52
IBNR	$ 0
Cumulative Number of Reported Claims | Claim	22
Fronting and Programs | Specialty Admitted Insurance | Accident year 2014
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 3,081
IBNR	$ 150
Cumulative Number of Reported Claims | Claim	858
Fronting and Programs | Specialty Admitted Insurance | Accident year 2015
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 8,444
IBNR	$ 452
Cumulative Number of Reported Claims | Claim	1,363
Fronting and Programs | Specialty Admitted Insurance | Accident year 2016
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 14,468
IBNR	$ 1,900
Cumulative Number of Reported Claims | Claim	2,815
Fronting and Programs | Specialty Admitted Insurance | Accident year 2017
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 24,728
IBNR	$ 5,244
Cumulative Number of Reported Claims | Claim	6,765
Fronting and Programs | Specialty Admitted Insurance | Accident year 2018
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 19,822
IBNR	$ 4,998
Cumulative Number of Reported Claims | Claim	7,318
Fronting and Programs | Specialty Admitted Insurance | Accident year 2019
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 19,020
IBNR	$ 9,119
Cumulative Number of Reported Claims | Claim	7,941
Fronting and Programs | Specialty Admitted Insurance | Accident year 2020
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 25,433
IBNR	$ 14,743
Cumulative Number of Reported Claims | Claim	6,956
Individual Risk Workers' Compensation | Specialty Admitted Insurance
Claims Development [Line Items]
Cumulative Number of Reported Claims | claim	4
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2011
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 35,252
IBNR	$ 532
Cumulative Number of Reported Claims | Claim	1,814
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2012
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 27,741
IBNR	$ 602
Cumulative Number of Reported Claims | Claim	1,323
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2013
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 10,598
IBNR	$ 262
Cumulative Number of Reported Claims | Claim	540
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2014
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 12,573
IBNR	$ 298
Cumulative Number of Reported Claims | Claim	850
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2015
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 16,492
IBNR	$ 423
Cumulative Number of Reported Claims | Claim	975
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2016
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 14,050
IBNR	$ 1,527
Cumulative Number of Reported Claims | Claim	836
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2017
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 18,810
IBNR	$ 3,436
Cumulative Number of Reported Claims | Claim	1,093
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2018
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 16,038
IBNR	$ 4,020
Cumulative Number of Reported Claims | Claim	1,238
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2019
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 21,056
IBNR	$ 2,989
Cumulative Number of Reported Claims | Claim	1,548
Individual Risk Workers' Compensation | Specialty Admitted Insurance | Accident year 2020
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 20,137
IBNR	$ 2,842
Cumulative Number of Reported Claims | Claim	1,305
Commercial Auto | Excess and Surplus Lines | Accident year 2013
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 1,277
IBNR	$ 1
Cumulative Number of Reported Claims | Claim	54
Commercial Auto | Excess and Surplus Lines | Accident year 2014
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 19,196
IBNR	$ 249
Cumulative Number of Reported Claims | Claim	7,764
Commercial Auto | Excess and Surplus Lines | Accident year 2015
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 37,839
IBNR	$ 639
Cumulative Number of Reported Claims | Claim	41,766
Commercial Auto | Excess and Surplus Lines | Accident year 2016
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 157,712
IBNR	$ 3,555
Cumulative Number of Reported Claims | Claim	89,084
Commercial Auto | Excess and Surplus Lines | Accident year 2017
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 319,472
IBNR	$ 4,303
Cumulative Number of Reported Claims | Claim	134,055
Commercial Auto | Excess and Surplus Lines | Accident year 2018
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 283,408
IBNR	$ 9,947
Cumulative Number of Reported Claims | Claim	97,076
Commercial Auto | Excess and Surplus Lines | Accident year 2019
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 240,773
IBNR	$ 40,372
Cumulative Number of Reported Claims | Claim	70,707
Commercial Auto | Excess and Surplus Lines | Accident year 2020
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 19,133
IBNR	$ 16,942
Cumulative Number of Reported Claims | Claim	498
Excluding Commercial Auto | Excess and Surplus Lines
Claims Development [Line Items]
Cumulative Number of Reported Claims | claim	46
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2011
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 104,280
IBNR	$ 2,038
Cumulative Number of Reported Claims | Claim	1,488
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2012
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 106,118
IBNR	$ 1,586
Cumulative Number of Reported Claims | Claim	1,850
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2013
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 82,517
IBNR	$ 3,488
Cumulative Number of Reported Claims | Claim	2,480
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2014
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 90,191
IBNR	$ 6,804
Cumulative Number of Reported Claims | Claim	2,198
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2015
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 110,466
IBNR	$ 5,409
Cumulative Number of Reported Claims | Claim	2,587
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2016
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 125,097
IBNR	$ 15,213
Cumulative Number of Reported Claims | Claim	3,023
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2017
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 124,265
IBNR	$ 29,548
Cumulative Number of Reported Claims | Claim	3,085
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2018
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 146,633
IBNR	$ 52,940
Cumulative Number of Reported Claims | Claim	4,267
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2019
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 194,759
IBNR	$ 123,212
Cumulative Number of Reported Claims | Claim	4,950
Excluding Commercial Auto | Excess and Surplus Lines | Accident year 2020
Claims Development [Line Items]
Incurred Losses and Loss Adj Expenses	$ 239,897
IBNR	$ 206,389
Cumulative Number of Reported Claims | Claim	3,115

Reinsurance - Narrative (Detail

Reinsurance - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid losses, net	$ 805,684	$ 668,045
Reinsurance recoverable on paid losses	$ 46,118	33,221
Percentage of reinsurance recoverables on unpaid losses for 3 largest reinsurers	47.80%
Prepaid reinsurance premiums ceded	$ 243,741	$ 178,976
Percentage of prepaid reinsurance premiums ceded for 3 largest reinsurers	52.70%
Largest reinsurer one
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid losses, net	$ 250,900
Prepaid reinsurance premiums ceded	72,000
Largest reinsurer two
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid losses, net	83,100
Prepaid reinsurance premiums ceded	36,200
Largest reinsurer three
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid losses, net	51,400
Prepaid reinsurance premiums ceded	$ 20,200

Reinsurance - Summary of Premiu

Reinsurance - Summary of Premiums Written, Premiums Earned, and Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Written premiums:
Direct	$ 1,103,994	$ 1,305,948	$ 1,027,222
Assumed	153,006	164,787	139,551
Ceded	(609,226)	(574,585)	(404,101)
Net written premiums	647,774	896,150	762,672
Earned premiums:
Direct	1,005,138	1,182,501	990,221
Assumed	145,867	150,330	208,192
Ceded	(544,199)	(509,085)	(383,015)
Net earned premiums	606,806	823,746	815,398
Losses and loss adjustment expenses:
Direct	709,545	953,548	769,490
Assumed	125,096	113,843	131,346
Ceded	(356,096)	(395,289)	(300,560)
Net	$ 478,545	$ 672,102	$ 600,276

Senior Debt (Details)

Senior Debt (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Aug. 02, 2017	May 26, 2004
2013 Facility
Line of Credit Facility [Line Items]
Current total capacity	$ 315,000,000
2013 Facility | Bank Holding Company
Line of Credit Facility [Line Items]
Commitment to lend	36,000,000
2013 Facility | Secured | JRG Re
Line of Credit Facility [Line Items]
Total capacity	102,500,000
Letters of credit outstanding	92,000,000
2013 Facility | Unsecured
Line of Credit Facility [Line Items]
Total capacity	212,500,000
Amount outstanding on line of credit	185,800,000	$ 133,300,000
Additional borrowings	$ 52,500,000
2013 Facility | LIBOR | Unsecured
Line of Credit Facility [Line Items]
Margin above LIBOR, percentage rate	1.50%
2017 Facility
Line of Credit Facility [Line Items]
Total capacity			$ 100,000,000
2017 Facility | Secured | JRG Re
Line of Credit Facility [Line Items]
Amount outstanding on line of credit	$ 17,500,000
2017 Facility | Unsecured
Line of Credit Facility [Line Items]
Amount outstanding on line of credit	61,500,000
Additional borrowings	$ 51,500,000
James River Group Senior Debt
Line of Credit Facility [Line Items]
Principal amount of Senior Debt				$ 15,000,000
James River Group Senior Debt | LIBOR
Line of Credit Facility [Line Items]
Margin above LIBOR, percentage rate				3.85%

Junior Subordinated Debt - Summ

Junior Subordinated Debt - Summary of Junior Subordinated Debt and Trust Preferred Securities (Details) - Junior Subordinated Debt $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
James River Capital Trust I
Debt Instrument [Line Items]
Issue date	May 26, 2004
Principal amount of Trust Preferred Securities	$ 7,000
Principal amount of Junior Subordinated Debt	7,217
Carrying amount of Junior Subordinated Debt net of repurchases	$ 7,217
Maturity date of Junior Subordinated Debt, unless accelerated earlier	May 24, 2034
Trust common stock	$ 217
Interest rate, per annum	Three-Month LIBOR plus 4.0%
James River Capital Trust II
Debt Instrument [Line Items]
Issue date	Dec. 15, 2004
Principal amount of Trust Preferred Securities	$ 15,000
Principal amount of Junior Subordinated Debt	15,464
Carrying amount of Junior Subordinated Debt net of repurchases	$ 15,464
Maturity date of Junior Subordinated Debt, unless accelerated earlier	Dec. 15, 2034
Trust common stock	$ 464
Interest rate, per annum	Three-Month LIBOR plus 3.4%
James River Capital Trust III
Debt Instrument [Line Items]
Issue date	Jun. 15, 2006
Principal amount of Trust Preferred Securities	$ 20,000
Principal amount of Junior Subordinated Debt	20,619
Carrying amount of Junior Subordinated Debt net of repurchases	$ 20,619
Maturity date of Junior Subordinated Debt, unless accelerated earlier	Jun. 15, 2036
Trust common stock	$ 619
Interest rate, per annum	Three-Month LIBOR plus 3.0%
James River Capital Trust IV
Debt Instrument [Line Items]
Issue date	Dec. 11, 2007
Principal amount of Trust Preferred Securities	$ 54,000
Principal amount of Junior Subordinated Debt	55,670
Carrying amount of Junior Subordinated Debt net of repurchases	$ 44,827
Maturity date of Junior Subordinated Debt, unless accelerated earlier	Dec. 15, 2037
Trust common stock	$ 1,670
Interest rate, per annum	Three-Month LIBOR plus 3.1%
Franklin Holdings II (Bermuda) Capital Trust I
Debt Instrument [Line Items]
Issue date	Jan. 10, 2008
Principal amount of Trust Preferred Securities	$ 30,000
Principal amount of Junior Subordinated Debt	30,928
Carrying amount of Junior Subordinated Debt net of repurchases	$ 15,928
Maturity date of Junior Subordinated Debt, unless accelerated earlier	Mar. 15, 2038
Trust common stock	$ 928
Interest rate, per annum	Three-Month LIBOR plus 4.0%

Junior Subordinated Debt - Narr

Junior Subordinated Debt - Narrative (Details) - Junior Subordinated Debt	12 Months Ended
	Dec. 31, 2020
Debt Instrument [Line Items]
Debt redemption percentage	100.00%
Deferred interest payment period (in years)	5 years

Capital Stock - Narrative (Deta

Capital Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized	200,000,000	200,000,000
Common stock, par value (in dollars per share)	$ 0.0002	$ 0.0002
Common stock, shares issued	30,649,261	30,424,391
Common stock, shares outstanding	30,649,261	30,424,391	29,988,460
Undesignated preferred stock, shares authorized	20,000,000	20,000,000
Undesignated stock par value (in dollars per share)	$ 0.00125	$ 0.00125
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common shares reserved for future issuance	4,321,150
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock unit dividend equivalents	$ 449	$ 433	$ 391
Dividends payable	$ 663	$ 623	$ 557

Capital Stock - Summary of Cash

Capital Stock - Summary of Cash Dividends Declared (Details) - USD ($)	Dec. 31, 2020	Oct. 27, 2020	Sep. 30, 2020	Jul. 28, 2020	Jun. 30, 2020	Apr. 28, 2020	Mar. 31, 2020	Feb. 19, 2020	Dec. 31, 2019	Nov. 05, 2019	Sep. 30, 2019	Jul. 30, 2019	Jun. 28, 2019	Apr. 30, 2019	Mar. 29, 2019	Feb. 20, 2019	Dec. 28, 2018	Nov. 07, 2018	Sep. 28, 2018	Aug. 01, 2018	Jun. 29, 2018	May 01, 2018	Mar. 30, 2018	Feb. 22, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Dividend declared per share (in dollars per share)		$ 0.30		$ 0.30		$ 0.30		$ 0.30		$ 0.30		$ 0.30		$ 0.30		$ 0.30		$ 0.30		$ 0.30		$ 0.30		$ 0.30	$ 1.20	$ 1.20	$ 1.20
Total Amount	$ 9,305,000		$ 9,292,000		$ 9,271,000		$ 9,269,000		$ 9,229,000		$ 9,231,000		$ 9,205,000		$ 9,146,000		$ 9,089,000		$ 9,081,000		$ 9,066,000		$ 9,049,000		$ 37,137,000	$ 36,811,000	$ 36,285,000

Equity Awards - Narrative (Deta

Equity Awards - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	0	0	0
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life of option (in years)	7 years
Total intrinsic value of options exercised	$ 3.8	$ 8.2	$ 4.6
Aggregate intrinsic value of options outstanding	7.8	7.1	9.4
Aggregate intrinsic value of options exercisable	$ 7.8	$ 7.1	$ 8.5
Fair value of shares used in calculation of intrinsic values (in dollars per share)	$ 49.15	$ 41.21	$ 36.54
Weighted-average remaining contractual life of options outstanding (in years)	2 years 1 month 6 days
Options granted	0	0	0
Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Total fair value of shares vested	$ 7.2	$ 5.3	$ 3.2
Unrecognized share based compensation expense	$ 11.1
Weighted-average period of unrecognized share based compensation expense (in years)	2 years 1 month 6 days
RSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
RSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	5 years
2014 Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares available for issuance	4,171,150
Number of shares available for grant	1,357,375
2014 Non-Employee Director Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares available for issuance	150,000
Number of shares available for grant	101,746
Increase in number of common shares authorized for issuance				100,000
Non-employee directors | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year

Equity Awards - Summary of Opti

Equity Awards - Summary of Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Granted (in shares)	0	0	0
Options
Shares
Beginning of year (in shares)	643,851	1,115,324	1,479,236
Granted (in shares)	0	0	0
Exercised (in shares)	(180,527)	(459,415)	(308,025)
Forfeited (in shares)	0	(12,058)	(55,887)
End of year (in shares)	463,324	643,851	1,115,324
Exercisable, end of year (in shares)	463,324	590,340	814,421
Weighted- Average Exercise Price
Beginning of year (in dollars per share)	$ 30.41	$ 29.02	$ 27.81
Granted (in dollars per share)	0	0	0
Exercised (in dollars per share)	25.70	26.87	22.01
Forfeited (in dollars per share)	0	36.84	35.69
End of year (in dollars per share)	32.25	30.41	29.02
Exercisable, end of year (in dollars per share)	$ 32.25	$ 29.34	$ 26.46

Equity Awards - Summary of RSU

Equity Awards - Summary of RSU Activity (Details) - RSUs - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Unvested, beginning of year (in shares)	340,368	300,142	178,882
Granted (in shares)	272,608	197,078	227,481
Vested (in shares)	(165,344)	(134,407)	(83,384)
Forfeited (in shares)	(47,776)	(22,445)	(22,837)
Unvested, end of year (in shares)	399,856	340,368	300,142
Weighted- Average Grant Date Fair Value
Unvested, beginning of year (in dollars per share)	$ 41.50	$ 39.22	$ 37.93
Granted (in dollars per share)	45.11	42.56	39.74
Vested (in dollars per share)	41.49	37.99	37.61
Forfeited (in dollars per share)	44.57	41.32	40.21
Unvested, end of year (in dollars per share)	$ 43.59	$ 41.50	$ 39.22

Equity Awards - Summary of Comp

Equity Awards - Summary of Compensation Expense and Related Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Share based compensation expense	$ 7,625	$ 7,178	$ 6,228
U.S. tax benefit on share based compensation expense	$ 1,001	$ 872	$ 716

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Examination [Line Items]
Percentage of dividend withholding tax	5.00%	5.00%	5.00%
Dividend distributions to intermediate holding company	$ 0	$ 0	$ 0
Increase to deferred tax asset for additional discount				$ 8,800,000
Deferred tax liability				$ 8,800,000
Transition provision expense			1,100,000
Income tax expense recognized over next six years		5,700,000
Income tax expense recognized over next six years per year		950,000
U.S. income before Federal income taxes	$ 25,100,000	70,700,000	37,500,000
Percentage of excise tax on reinsurance premiums paid	1.00%
Payment of federal excise taxes	$ 468,000	586,000	823,000
Excise taxes paid	$ 1,200,000	$ 1,500,000	$ 2,100,000
Bermuda
Income Tax Examination [Line Items]
Federal statutory tax rates	0.00%	0.00%	0.00%
United States
Income Tax Examination [Line Items]
Federal statutory tax rates	21.00%	21.00%	21.00%

Income Taxes - Summary of Incom

Income Taxes - Summary of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal income tax expense at applicable statutory rates	$ 5,272	$ 14,843	$ 7,875
Tax-exempt investment income	(260)	(230)	(272)
Dividends received deduction	(283)	(307)	(307)
Excess tax benefits on share based compensation	(679)	(1,099)	(567)
Effect of tax rate reduction on deferred tax liability	0	0	220
Base Erosion and Anti-Abuse Tax	2,843	0	0
Other	17	99	145
Federal income tax expense	6,910	13,306	7,094
U.S. state income tax expense (benefit)	203	222	(86)
Total income tax expense	$ 7,113	$ 13,528	$ 7,008

Income Taxes - Summary of Net D

Income Taxes - Summary of Net Deferred Tax Asset (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Accrued compensation expenses	$ 2,308	$ 2,563
Reserve for losses and loss adjustment expenses	14,265	12,286
Unearned premiums	9,753	8,226
Share based compensation	1,427	1,482
Allowance for doubtful accounts	2,130	1,188
Property and equipment	213	16
Other	4,810	1,974
Total deferred tax assets	34,906	27,735
Deferred tax liabilities:
Intangible assets	7,324	7,381
Net unrealized gains	12,201	5,792
Deferred policy acquisition costs	4,786	4,448
Equity method investments	8,839	9,316
Other	2,861	134
Total deferred tax liabilities	36,011	27,071
Net deferred tax (liabilities) assets	$ (1,105)
Net deferred tax (liabilities) assets		$ 664

Other Operating Expenses and _3

Other Operating Expenses and Other Expenses - Summary of Other Operating Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Operating Expenses And Other Expenses [Abstract]
Amortization of policy acquisition costs	$ 75,578	$ 83,893	$ 111,103
Other underwriting expenses of the insurance segments	60,502	59,351	63,029
Other operating expenses of the Corporate and Other segment	29,418	27,664	26,903
Total	$ 165,498	$ 170,908	$ 201,035

Other Operating Expenses and _4

Other Operating Expenses and Other Expenses - Summary of Other Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Operating Expenses And Other Expenses [Abstract]
Employee severance	$ 1,967	$ 1,055	$ 1,386
Income on leased building the Company was previously deemed to own for accounting purposes	0	0	(623)
Legal and professional services related to secondary share offerings	0	0	337
Other	171	0	0
Impairment of intangible asset	0	0	200
Total	$ 2,138	$ 1,055	$ 1,300

Employee Benefits (Details)

Employee Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Maximum matching employer contribution	6.00%
Expense associated with Savings Plans	$ 3.5	$ 3.2	$ 2.9

Commitments and Contingent Li_2

Commitments and Contingent Liabilities - Narrative (Details)	Dec. 31, 2020USD ($)letter_of_credit_facility	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Contingent Liabilities [Line Items]
Amount of collateral held	$ 859,920,000	$ 1,199,164,000	$ 0	$ 0
JRG Reinsurance Company, Ltd.
Contingent Liabilities [Line Items]
Letter of credit facilities | letter_of_credit_facility	3
Total amount deposited in trust accounts	$ 304,600,000
JRG Reinsurance Company, Ltd. | Letter of credit 75 million
Contingent Liabilities [Line Items]
Letters of credit facility, amount	75,000,000
Amount of letters of credit issued	7,300,000
Assets deposited for securing letters of credit	14,600,000
JRG Reinsurance Company, Ltd. | 2013 Facility
Contingent Liabilities [Line Items]
Amount of letters of credit issued	92,000,000
Assets deposited for securing letters of credit	115,700,000
JRG Reinsurance Company, Ltd. | 2017 Facility
Contingent Liabilities [Line Items]
Amount of letters of credit issued	17,500,000
Assets deposited for securing letters of credit	28,400,000
Raiser
Contingent Liabilities [Line Items]
Amount of collateral held	$ 859,900,000

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) - Summary of Components of Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gains (losses) arising during the period, before U.S. income taxes	$ 58,704	$ 51,381	$ (23,201)
U.S. income taxes	(6,967)	(3,510)	483
Unrealized gains (losses) arising during the period, net of U.S. income taxes	51,737	47,871	(22,718)
Less reclassification adjustment:
Net realized investment gains (losses)	1,045	1,081	(554)
U.S. income taxes	(93)	(152)	39
Reclassification adjustment for investment gains (losses) realized in net income	952	929	(515)
Other comprehensive income (loss)	$ 50,785	$ 46,942	$ (22,203)

Other Comprehensive Income (L_4

Other Comprehensive Income (Loss) - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net realized investment gains (losses)	$ 1,045	$ 1,081	$ (554)
Bank loan participations net realized and unrealized gains (losses)	(15,414)	(10,056)	1,113
Equity securities net realized and unrealized gains (losses)	$ (1,656)	$ 6,036	$ (6,032)

Segment Information - Narrative

Segment Information - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)SegmentcompanybrokerUnderwriting_divisionagency	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	4
Fee income	$ 3,400	$ 9,500	$ 13,900
Number of underwriting divisions | Underwriting_division	15
Gross written premiums	$ 1,257,000	1,470,735	1,166,773
Excess and Surplus Lines
Segment Reporting Information [Line Items]
Number of brokers | broker	3
Fee income	$ 1,600	9,100	13,900
Number of underwriting divisions | Underwriting_division	13
Gross written premiums	$ 699,143	922,320	656,538
Excess and Surplus Lines | Broker one
Segment Reporting Information [Line Items]
Gross written premiums	$ 165,800
Consolidated gross written premiums percentage	13.20%
Gross written premiums percentage	23.70%
Excess and Surplus Lines | Broker two
Segment Reporting Information [Line Items]
Gross written premiums	$ 157,500
Consolidated gross written premiums percentage	12.50%
Gross written premiums percentage	22.50%
Excess and Surplus Lines | Broker three
Segment Reporting Information [Line Items]
Gross written premiums	$ 128,900
Consolidated gross written premiums percentage	10.30%
Gross written premiums percentage	18.40%
Specialty Admitted Insurance
Segment Reporting Information [Line Items]
Fee income	$ 1,800	421
Number of underwriting divisions | Underwriting_division	1
Gross written premiums	$ 408,691	387,642	374,346
Number of agencies | agency	2
Specialty Admitted Insurance | Agency one
Segment Reporting Information [Line Items]
Gross written premiums	$ 125,500
Consolidated gross written premiums percentage	10.00%
Gross written premiums percentage	30.70%
Specialty Admitted Insurance | Agency two
Segment Reporting Information [Line Items]
Gross written premiums	$ 46,400
Consolidated gross written premiums percentage	3.70%
Gross written premiums percentage	11.40%
Casualty Reinsurance
Segment Reporting Information [Line Items]
Number of brokers | broker	3
Number of underwriting divisions | Underwriting_division	1
Gross written premiums	$ 149,166	$ 160,773	$ 135,889
Number of unaffiliated ceding companies | company	3
Casualty Reinsurance | Broker one
Segment Reporting Information [Line Items]
Gross written premiums	$ 55,800
Consolidated gross written premiums percentage	4.40%
Gross written premiums percentage	37.40%
Casualty Reinsurance | Broker two
Segment Reporting Information [Line Items]
Gross written premiums	$ 34,900
Consolidated gross written premiums percentage	2.80%
Gross written premiums percentage	23.40%
Casualty Reinsurance | Broker three
Segment Reporting Information [Line Items]
Gross written premiums	$ 22,400
Consolidated gross written premiums percentage	1.80%
Gross written premiums percentage	15.00%
Casualty Reinsurance | Unaffiliated ceding company one
Segment Reporting Information [Line Items]
Gross written premiums	$ 85,100
Consolidated gross written premiums percentage	6.80%
Gross written premiums percentage	57.00%
Casualty Reinsurance | Unaffiliated ceding company two
Segment Reporting Information [Line Items]
Gross written premiums	$ 23,100
Consolidated gross written premiums percentage	1.80%
Gross written premiums percentage	15.50%
Casualty Reinsurance | Unaffiliated ceding company three
Segment Reporting Information [Line Items]
Gross written premiums	$ 19,100
Consolidated gross written premiums percentage	1.50%
Gross written premiums percentage	12.80%

Segment Information - Schedule

Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Gross written premiums	$ 1,257,000	$ 1,470,735	$ 1,166,773
Net earned premiums	606,806	823,746	815,398
Segment revenues	668,689	907,125	885,599
Net investment income	73,368	75,652	61,256
Interest expense	10,033	10,596	11,553
Underwriting profit (loss) of operating segments	(4,427)	17,909	54,909
Goodwill	181,831	181,831	181,831
Segment assets	5,063,072	5,024,405	3,136,776
Excess and Surplus Lines
Segment Reporting Information [Line Items]
Gross written premiums	699,143	922,320	656,538
Net earned premiums	415,168	625,528	555,684
Segment revenues	429,918	657,501	580,785
Net investment income	18,664	21,358	14,456
Interest expense	0	0	0
Underwriting profit (loss) of operating segments	9,752	19,157	42,834
Goodwill	181,831	181,831	181,831
Segment assets	2,208,344	2,481,934	972,111
Specialty Admitted Insurance
Segment Reporting Information [Line Items]
Gross written premiums	408,691	387,642	374,346
Net earned premiums	57,505	54,338	55,146
Segment revenues	62,790	61,241	56,717
Net investment income	3,392	3,802	3,262
Interest expense	0	0	0
Underwriting profit (loss) of operating segments	4,185	5,913	6,972
Goodwill	0	0	0
Segment assets	907,604	786,433	633,689
Casualty Reinsurance
Segment Reporting Information [Line Items]
Gross written premiums	149,166	160,773	135,889
Net earned premiums	134,133	143,880	204,568
Segment revenues	166,837	183,700	243,178
Net investment income	42,554	46,325	38,838
Interest expense	0	0	0
Underwriting profit (loss) of operating segments	(18,364)	(7,161)	5,103
Goodwill	0	0	0
Segment assets	1,899,328	1,699,473	1,453,754
Corporate and other segment
Segment Reporting Information [Line Items]
Gross written premiums	0	0	0
Net earned premiums	0	0	0
Segment revenues	9,144	4,683	4,919
Net investment income	8,758	4,167	4,700
Interest expense	10,033	10,596	11,553
Underwriting profit (loss) of operating segments	0	0	0
Goodwill	0	0	0
Segment assets	$ 47,796	$ 56,565	$ 77,222

Segment Information - Reconcili

Segment Information - Reconciliation of Underwriting Profit (Loss) of Insurance Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Underwriting profit (loss) of operating segments	$ (4,427)	$ 17,909	$ 54,909
Other operating expenses	(29,418)	(27,664)	(26,903)
Underwriting profit	(33,845)	(9,755)	28,006
Net investment income	73,368	75,652	61,256
Net realized investment (losses) gains	(16,030)	(2,919)	(5,479)
Other income	1,153	1,137	505
Other expenses	(2,138)	(1,055)	(1,300)
Interest expense	(10,033)	(10,596)	(11,553)
Amortization of intangible assets	(538)	(597)	(597)
Income before income taxes	11,937	51,867	70,838
Excess and Surplus Lines
Segment Reporting Information [Line Items]
Underwriting profit (loss) of operating segments	9,752	19,157	42,834
Net investment income	18,664	21,358	14,456
Interest expense	0	0	0
Amortization of intangible assets	(366)	(362)	(362)
Specialty Admitted Insurance
Segment Reporting Information [Line Items]
Underwriting profit (loss) of operating segments	4,185	5,913	6,972
Net investment income	3,392	3,802	3,262
Interest expense	0	0	0
Amortization of intangible assets	(172)	(235)	(235)
Casualty Reinsurance
Segment Reporting Information [Line Items]
Underwriting profit (loss) of operating segments	(18,364)	(7,161)	5,103
Net investment income	42,554	46,325	38,838
Interest expense	0	0	0
Corporate and other segment
Segment Reporting Information [Line Items]
Underwriting profit (loss) of operating segments	0	0	0
Net investment income	8,758	4,167	4,700
Interest expense	$ (10,033)	$ (10,596)	$ (11,553)

Segment Information - Gross Wri

Segment Information - Gross Written Premiums (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total gross written premiums	$ 1,257,000	$ 1,470,735	$ 1,166,773
Excess and Surplus Lines
Segment Reporting Information [Line Items]
Total gross written premiums	699,143	922,320	656,538
Excess and Surplus Lines | Commercial Auto
Segment Reporting Information [Line Items]
Total gross written premiums	30,029	405,565	322,126
Excess and Surplus Lines | Excess Casualty
Segment Reporting Information [Line Items]
Total gross written premiums	213,037	118,954	66,452
Excess and Surplus Lines | General Casualty
Segment Reporting Information [Line Items]
Total gross written premiums	125,433	115,832	54,127
Excess and Surplus Lines | Manufacturers and Contractors
Segment Reporting Information [Line Items]
Total gross written premiums	122,880	105,096	79,160
Excess and Surplus Lines | Energy
Segment Reporting Information [Line Items]
Total gross written premiums	51,109	45,442	33,942
Excess and Surplus Lines | Excess Property
Segment Reporting Information [Line Items]
Total gross written premiums	37,332	31,606	16,963
Excess and Surplus Lines | Allied Health
Segment Reporting Information [Line Items]
Total gross written premiums	26,918	26,713	30,450
Excess and Surplus Lines | Life Sciences
Segment Reporting Information [Line Items]
Total gross written premiums	35,163	24,462	16,636
Excess and Surplus Lines | Small Business
Segment Reporting Information [Line Items]
Total gross written premiums	24,790	19,725	14,808
Excess and Surplus Lines | Environmental
Segment Reporting Information [Line Items]
Total gross written premiums	17,753	16,539	10,499
Excess and Surplus Lines | Professional Liability
Segment Reporting Information [Line Items]
Total gross written premiums	6,881	6,441	5,916
Excess and Surplus Lines | Sports and Entertainment
Segment Reporting Information [Line Items]
Total gross written premiums	6,118	4,212	3,685
Excess and Surplus Lines | Medical Professionals
Segment Reporting Information [Line Items]
Total gross written premiums	1,700	1,733	1,774
Specialty Admitted Insurance
Segment Reporting Information [Line Items]
Total gross written premiums	408,691	387,642	374,346
Casualty Reinsurance
Segment Reporting Information [Line Items]
Total gross written premiums	$ 149,166	$ 160,773	$ 135,889

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	$ 1,783,642	$ 1,433,626
Equity securities:
Equity securities	88,975	80,735
Bank loan participations	147,604
State and municipal
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	296,405	167,101
Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	293,848	264,146
Corporate
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	766,822	632,221
Commercial mortgage and asset-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	326,719	252,457
U.S. Treasury securities and obligations guaranteed by the U.S. government
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	99,848	115,667
Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale		2,034
Recurring basis
Equity securities:
Bank loan participations	147,604
Short-term investments	130,289	156,925
Recurring basis | Fixed maturity securities
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	1,783,642	1,433,626
Recurring basis | State and municipal
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	296,405	167,101
Recurring basis | Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	293,848	264,146
Recurring basis | Corporate
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	766,822	632,221
Recurring basis | Commercial mortgage and asset-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	326,719	252,457
Recurring basis | U.S. Treasury securities and obligations guaranteed by the U.S. government
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	99,848	115,667
Recurring basis | Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale		2,034
Recurring basis | Equity securities
Equity securities:
Equity securities	88,975	80,735
Recurring basis | Preferred stock
Equity securities:
Equity securities	67,495	62,747
Recurring basis | Common stock
Equity securities:
Equity securities	21,480	17,988
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1
Equity securities:
Bank loan participations	0
Short-term investments	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Fixed maturity securities
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	99,384	115,173
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | State and municipal
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Corporate
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Commercial mortgage and asset-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | U.S. Treasury securities and obligations guaranteed by the U.S. government
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	99,384	115,173
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale		0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Equity securities
Equity securities:
Equity securities	15,793	14,669
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Preferred stock
Equity securities:
Equity securities	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Common stock
Equity securities:
Equity securities	15,793	14,669
Recurring basis | Significant Other Observable Inputs Level 2
Equity securities:
Bank loan participations	147,296
Short-term investments	130,289	156,925
Recurring basis | Significant Other Observable Inputs Level 2 | Fixed maturity securities
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	1,684,258	1,318,453
Recurring basis | Significant Other Observable Inputs Level 2 | State and municipal
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	296,405	167,101
Recurring basis | Significant Other Observable Inputs Level 2 | Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	293,848	264,146
Recurring basis | Significant Other Observable Inputs Level 2 | Corporate
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	766,822	632,221
Recurring basis | Significant Other Observable Inputs Level 2 | Commercial mortgage and asset-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	326,719	252,457
Recurring basis | Significant Other Observable Inputs Level 2 | U.S. Treasury securities and obligations guaranteed by the U.S. government
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	464	494
Recurring basis | Significant Other Observable Inputs Level 2 | Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale		2,034
Recurring basis | Significant Other Observable Inputs Level 2 | Equity securities
Equity securities:
Equity securities	72,510	66,023
Recurring basis | Significant Other Observable Inputs Level 2 | Preferred stock
Equity securities:
Equity securities	67,495	62,747
Recurring basis | Significant Other Observable Inputs Level 2 | Common stock
Equity securities:
Equity securities	5,015	3,276
Recurring basis | Significant Unobservable Inputs Level 3
Equity securities:
Bank loan participations	308
Short-term investments	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Fixed maturity securities
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | State and municipal
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Corporate
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Commercial mortgage and asset-backed
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale		0	$ 4,400
Recurring basis | Significant Unobservable Inputs Level 3 | U.S. Treasury securities and obligations guaranteed by the U.S. government
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Fixed maturity securities, available-for-sale		0
Recurring basis | Significant Unobservable Inputs Level 3 | Equity securities
Equity securities:
Equity securities	672	43
Recurring basis | Significant Unobservable Inputs Level 3 | Preferred stock
Equity securities:
Equity securities	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Common stock
Equity securities:
Equity securities	$ 672	$ 43

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Available-for-Sale Fixed Maturity Securities Measured at Fair Value on a Recurring Basis (Details) - Available-for-sale fixed maturity and equity securities - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 43	$ 4,442	$ 4,680
Transfers in to Level 3	358	3,010	0
Transfers out of Level 3	(767)	(7,238)	0
Purchases	1,417		214
Sales	0	0	0
Maturities and calls	(17)		(452)
Amortization of discount	2	0	0
Total gains or losses (realized/unrealized) - Included in earnings	(56)	(171)	0
Total gains or losses (realized/unrealized) - Included in other comprehensive income	0	0	0
Ending balance	$ 980	$ 43	$ 4,442

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 88,975	$ 80,735
Available-for-sale fixed maturity and equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	980	43	$ 4,442	$ 4,680
Equity securities | Recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	88,975	80,735
Equity securities | Significant Unobservable Inputs Level 3 | Recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 672	$ 43

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring basis $ in Thousands	Dec. 31, 2019USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired bank loan participations held for investment	$ 6,949
Quoted Prices in Active Markets for Identical Assets Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired bank loan participations held for investment	0
Significant Other Observable Inputs Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired bank loan participations held for investment	0
Significant Unobservable Inputs Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired bank loan participations held for investment	$ 6,949

Fair Value Measurements - Sum_4

Fair Value Measurements - Summary of the Carrying Value and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Fixed maturity securities, available-for-sale	$ 1,783,642	$ 1,433,626
Equity securities	88,975	80,735
Bank loan participations	147,604
Bank loan participations		260,864
Cash and cash equivalents	162,260	206,912
Restricted cash equivalents	859,920	1,199,164	$ 0	$ 0
Short-term investments	130,289	156,925
Liabilities
Senior debt	262,300	158,300
Carrying Value
Assets
Fixed maturity securities, available-for-sale	1,783,642	1,433,626
Equity securities	88,975	80,735
Bank loan participations	147,604
Bank loan participations		260,864
Cash and cash equivalents	162,260	206,912
Restricted cash equivalents	859,920	1,199,164
Short-term investments	130,289	156,925
Other invested assets – notes receivable	4,500	13,250
Liabilities
Senior debt	262,300	158,300
Junior subordinated debt	104,055	104,055
Fair Value
Assets
Fixed maturity securities, available-for-sale	1,783,642	1,433,626
Equity securities	88,975	80,735
Bank loan participations	147,604
Bank loan participations		252,423
Cash and cash equivalents	162,260	206,912
Restricted cash equivalents	859,920	1,199,164
Short-term investments	130,289	156,925
Other invested assets – notes receivable	5,302	18,756
Liabilities
Senior debt	250,953	158,043
Junior subordinated debt	$ 110,612	$ 122,193

Statutory Matters - Schedule of

Statutory Matters - Schedule of Statutory Accounting (Details) - United States - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statutory Accounting Practices [Line Items]
Statutory net (loss) income	$ (710)	$ 3,586	$ 6,770
Statutory capital and surplus	286,449	266,715	241,668
Minimum required statutory capital and surplus	$ 100,170	$ 111,208	$ 24,850

Statutory Matters - Narrative (

Statutory Matters - Narrative (Details) - Casualty Reinsurance - Bermuda - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statutory Accounting Practices [Line Items]
Minimum statutory solvency margin	$ 172.9	$ 161.4
Actual statutory capital and surplus	615.2	502.6
Statutory net (loss) income	$ 20.8	53.2	$ 86.5
Combined ECR		$ 377.3
Minimum liquidity ratio	75.00%

Dividend Restrictions (Details)

Dividend Restrictions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statutory Accounting Practices [Line Items]
Percentage of dividend withholding tax for distributions	5.00%
Percentage of dividend distribution tax	30.00%
Retained earnings	$ 49,227	$ 89,586
United States
Statutory Accounting Practices [Line Items]
Dividend limitations percentage of statutory surplus	10.00%
Maximum amount of dividends available without regulatory approval	$ 28,600
Bermuda
Statutory Accounting Practices [Line Items]
Maximum amount of dividends and return of capital available	$ 153,800

Other Related Party Transacti_2

Other Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Minority interest in partnership
Related Party Transaction [Line Items]
Operating costs under lease	$ 1,900	$ 2,100	$ 2,600
Chief Executive Officer
Related Party Transaction [Line Items]
Total fees paid for the use of plane	$ 0	$ 0	$ 123

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 17, 2021	Jan. 14, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Investment in notes receivable			$ 1,937	$ 0	$ 6,993
Renewable Energy Bridge Financing Notes
Subsequent Event [Line Items]
Investment interest rate			15.00%
RSUs
Subsequent Event [Line Items]
Number of awards granted			272,608	197,078	227,481
Fair value on grant date			$ 45.11	$ 42.56	$ 39.74
Vesting period (in years)			3 years
RSUs | Minimum
Subsequent Event [Line Items]
Vesting period (in years)			1 year
RSUs | Maximum
Subsequent Event [Line Items]
Vesting period (in years)			5 years
Subsequent event
Subsequent Event [Line Items]
Dividends payable, per common share	$ 0.30
Subsequent event | Renewable Energy Bridge Financing Notes
Subsequent Event [Line Items]
Investment interest rate		12.00%
Subsequent event | Corporate and other segment | Renewable Energy Bridge Financing Notes
Subsequent Event [Line Items]
Investment in notes receivable		$ 5,000
Subsequent event | Excess and Surplus Lines | Renewable Energy Bridge Financing Notes
Subsequent Event [Line Items]
Investment in notes receivable		$ 4,000
Subsequent event | 2014 Long Term Incentive Plan | RSUs
Subsequent Event [Line Items]
Number of awards granted	138,936
Fair value on grant date	$ 50.24
Subsequent event | 2014 Long Term Incentive Plan | RSUs | Minimum
Subsequent Event [Line Items]
Vesting period (in years)	1 year
Subsequent event | 2014 Long Term Incentive Plan | RSUs | Maximum
Subsequent Event [Line Items]
Vesting period (in years)	3 years

SCHEDULE I - Summary of Inves_2

SCHEDULE I - Summary of Investments - Other than Investments in Related Parties (Details) $ in Thousands	Dec. 31, 2020USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amount at which shown on Balance Sheet	$ 2,162,413
Equity securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	81,698
Fair Value	88,975
Amount at which shown on Balance Sheet	88,975
Preferred stock
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	54,228
Fair Value	67,495
Amount at which shown on Balance Sheet	67,495
Common stock
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	27,470
Fair Value	21,480
Amount at which shown on Balance Sheet	21,480
Bank loan participations, held-for-investment, net of allowance
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	154,728
Fair Value	147,604
Amount at which shown on Balance Sheet	147,604
Short-term investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	130,289
Fair Value	130,289
Amount at which shown on Balance Sheet	130,289
Other invested assets
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amount at which shown on Balance Sheet	11,903
Available-for-sale Securities | Fixed maturity securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	1,690,890
Fair Value	1,783,642
Amount at which shown on Balance Sheet	1,783,642
Available-for-sale Securities | State and municipal
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	277,241
Fair Value	296,405
Amount at which shown on Balance Sheet	296,405
Available-for-sale Securities | Residential mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	286,104
Fair Value	293,848
Amount at which shown on Balance Sheet	293,848
Available-for-sale Securities | Corporate
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	715,145
Fair Value	766,822
Amount at which shown on Balance Sheet	766,822
Available-for-sale Securities | Commercial mortgage and asset-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	314,911
Fair Value	326,719
Amount at which shown on Balance Sheet	326,719
Available-for-sale Securities | U.S. Treasury securities and obligations guaranteed by the U.S. government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	97,489
Fair Value	99,848
Amount at which shown on Balance Sheet	$ 99,848

SCHEDULE II - Condensed Finan_2

SCHEDULE II - Condensed Financial Information of Registrant (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets [Abstract]
Cash and cash equivalents	$ 162,260	$ 206,912
Other assets	82,115	80,227
Total assets	5,063,072	5,024,405	$ 3,136,776
Liabilities:
Accrued expenses	55,989	58,416
Senior debt	262,300	158,300
Junior subordinated debt	104,055	104,055
Other liabilities	51,213	46,464
Total liabilities	4,267,464	4,245,824
Commitments and contingent liabilities
Shareholders’ equity:
Class A common shares	6	6
Additional paid-in capital	664,476	657,875
Retained earnings	49,227	89,586
Accumulated other comprehensive income	81,899	31,114
Total shareholders’ equity	795,608	778,581	709,241	$ 694,699
Total liabilities and shareholders’ equity	5,063,072	5,024,405
Parent Company
Assets [Abstract]
Cash and cash equivalents	571	1,521	$ 240	$ 2,849
Investment in subsidiaries	1,145,887	987,221
Due from subsidiaries	1,140	7,371
Other assets	3,116	2,842
Total assets	1,150,714	998,955
Liabilities:
Accrued expenses	1,824	1,592
Senior debt	247,300	143,300
Junior subordinated debt	15,928	15,928
Notes payable to subsidiary	70,000	40,000
Due to subsidiaries	19,391	18,822
Other liabilities	663	732
Total liabilities	355,106	220,374
Commitments and contingent liabilities
Shareholders’ equity:
Class A common shares	6	6
Additional paid-in capital	664,476	657,875
Retained earnings	49,227	89,586
Accumulated other comprehensive income	81,899	31,114
Total shareholders’ equity	795,608	778,581
Total liabilities and shareholders’ equity	$ 1,150,714	$ 998,955

SCHEDULE II - Condensed Finan_3

SCHEDULE II - Condensed Financial Information of Registrant (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Other income	$ 4,545	$ 10,646	$ 14,424
Total revenues	668,689	907,125	885,599
Expenses:
Other operating expenses	165,498	170,908	201,035
Other expenses	2,138	1,055	1,300
Interest expense	10,033	10,596	11,553
Total expenses	656,752	855,258	814,761
Loss before equity in net income of subsidiaries	11,937	51,867	70,838
Equity in net income of subsidiaries	3,208	4,598	3,540
Net income	4,824	38,339	63,830
Other comprehensive (loss) income:
Equity in other comprehensive earnings (losses) of subsidiaries	50,785	46,942	(22,203)
Total comprehensive income	55,609	85,281	41,627
Parent Company
Revenues:
Other income	45	61	58
Total revenues	45	61	58
Expenses:
Other operating expenses	14,960	14,267	13,768
Other expenses	0	0	337
Interest expense	6,234	5,047	5,122
Total expenses	21,194	19,314	19,227
Loss before equity in net income of subsidiaries	(21,149)	(19,253)	(19,169)
Equity in net income of subsidiaries	25,973	57,592	82,999
Net income	4,824	38,339	63,830
Other comprehensive (loss) income:
Equity in other comprehensive earnings (losses) of subsidiaries	50,785	46,942	(22,203)
Total comprehensive income	$ 55,609	$ 85,281	$ 41,627

SCHEDULE II - Condensed Finan_4

SCHEDULE II - Condensed Financial Information of Registrant (Details 2) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income		$ 4,824	$ 38,339	$ 63,830
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Provision for depreciation and amortization		5,019	4,063	4,215
Share based compensation expense		7,625	7,178	6,228
Net cash (used in) provided by operating activities	[1]	(273,830)	1,489,022	290,028
Investing activities
Net cash used in investing activities		(175,991)	(263,359)	(266,772)
Financing activities
Dividends paid		(37,051)	(36,720)	(36,123)
Senior debt issuance		164,000	60,000	20,000
Senior debt repayments		(60,000)	(20,000)	0
Issuances of common shares under equity incentive plans		2,580	8,286	5,172
Common share repurchases		(3,604)	(2,899)	(2,239)
Net cash provided by (used in) financing activities		65,925	7,956	(14,294)
Cash and cash equivalents at beginning of year		206,912
Cash and cash equivalents at end of year		162,260	206,912
Supplemental information
Interest paid		11,305	12,354	11,269
Parent Company
Operating activities
Net income		4,824	38,339	63,830
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Provision for depreciation and amortization		216	182	176
Share based compensation expense		7,625	7,178	6,228
Equity in undistributed earnings of subsidiaries		(25,973)	(49,592)	6,000
Changes in operating assets and liabilities:		6,433	(2,782)	(5,653)
Net cash (used in) provided by operating activities		(6,875)	(6,675)	70,581
Investing activities
Net cash used in investing activities		0	0	0
Financing activities
Dividends paid		(37,051)	(36,720)	(36,123)
Senior debt issuance		164,000	60,000	20,000
Senior debt repayments		(60,000)	(20,000)	0
Subsidiary note issuance		30,000	0	0
Subsidiary note repayments		0	0	(60,000)
Contribution to subsidiary		(90,000)	0	0
Debt issue costs paid		0	(711)	0
Issuances of common shares under equity incentive plans		2,580	8,286	5,172
Common share repurchases		(3,604)	(2,899)	(2,239)
Net cash provided by (used in) financing activities		5,925	7,956	(73,190)
Increase in cash and cash equivalents		(950)	1,281	(2,609)
Cash and cash equivalents at beginning of year		1,521	240	2,849
Cash and cash equivalents at end of year		571	1,521	240
Supplemental information
Interest paid		$ 6,530	$ 5,710	$ 5,052
[1]	Cash used in operating activities for the year ended December 31, 2020 primarily reflects $339.2 million of restricted cash equivalents returned to a former insured, per the terms of a collateral trust (see Amounts Recoverable from an Indemnifying Party in the Liquidity and Capital Resources discussion of Management's Discussion and Analysis of Financial Condition and Results of Operations). Excluding the reduction in the collateral funds, cash provided by operating activities was $65.4 million for the year ended December 31, 2020.

SCHEDULE II - Condensed Finan_5

SCHEDULE II - Condensed Financial Information of Registrant - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Shareholders' equity	$ 795,608		$ 778,581	$ 709,241	$ 694,699
Cumulative Effect, Period of Adoption, Adjustment
Condensed Financial Statements, Captions [Line Items]
Shareholders' equity				8,280
ASU 2019-05 | Cumulative Effect, Period of Adoption, Adjustment
Condensed Financial Statements, Captions [Line Items]
Fair value adjustment		$ 8,400
Shareholders' equity			(7,827)
ASU 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Condensed Financial Statements, Captions [Line Items]
Shareholders' equity			(265)
Retained Earnings
Condensed Financial Statements, Captions [Line Items]
Shareholders' equity	$ 49,227		89,586	79,753	$ 48,198
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
Condensed Financial Statements, Captions [Line Items]
Shareholders' equity				$ 8,280
Retained Earnings | ASU 2019-05 | Cumulative Effect, Period of Adoption, Adjustment
Condensed Financial Statements, Captions [Line Items]
Shareholders' equity		(7,800)	(7,827)
Retained Earnings | ASU 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Condensed Financial Statements, Captions [Line Items]
Shareholders' equity		$ (265)	$ (265)

SCHEDULE III - Supplementary _2

SCHEDULE III - Supplementary Insurance Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	$ 62,953	$ 62,006	$ 54,450
Reserve for Losses and Loss Adjustment Expenses	2,192,080	2,045,506	1,661,459
Unearned Premiums	630,371	524,377	386,473
Net Earned Premiums	606,806	823,746	815,398
Net Investment Income	73,368	75,652	61,256
Losses and Loss Adjustment Expenses	478,545	672,102	600,276
Amortization of Policy Acquisition Costs	75,578	83,893	111,103
Other Operating Expenses	165,498	170,908	201,035
Net Written Premiums	647,774	896,150	762,672
Excess and Surplus Lines
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	25,875	24,428	16,736
Reserve for Losses and Loss Adjustment Expenses	1,276,054	1,245,581	960,562
Unearned Premiums	345,976	267,924	175,231
Net Earned Premiums	415,168	625,528	555,684
Net Investment Income	18,664	21,358	14,456
Losses and Loss Adjustment Expenses	318,467	528,133	437,904
Amortization of Policy Acquisition Costs	49,387	49,720	48,299
Other Operating Expenses	88,520	87,326	88,865
Net Written Premiums	450,346	685,814	571,098
Specialty Admitted Insurance
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	(3,073)	(2,902)	(1,829)
Reserve for Losses and Loss Adjustment Expenses	600,309	511,027	426,315
Unearned Premiums	136,355	115,606	84,659
Net Earned Premiums	57,505	54,338	55,146
Net Investment Income	3,392	3,802	3,262
Losses and Loss Adjustment Expenses	41,928	34,860	32,623
Amortization of Policy Acquisition Costs	(4,525)	(3,560)	(1,792)
Other Operating Expenses	13,213	13,986	15,551
Net Written Premiums	59,884	58,637	55,840
Casualty Reinsurance
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	40,151	40,480	39,543
Reserve for Losses and Loss Adjustment Expenses	315,717	288,898	274,582
Unearned Premiums	148,040	140,847	126,583
Net Earned Premiums	134,133	143,880	204,568
Net Investment Income	42,554	46,325	38,838
Losses and Loss Adjustment Expenses	118,150	109,109	129,749
Amortization of Policy Acquisition Costs	30,716	37,733	64,596
Other Operating Expenses	34,347	41,932	69,716
Net Written Premiums	137,544	151,699	135,734
Corporate and other segment
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	0	0	0
Reserve for Losses and Loss Adjustment Expenses	0	0	0
Unearned Premiums	0	0	0
Net Earned Premiums	0	0	0
Net Investment Income	8,758	4,167	4,700
Losses and Loss Adjustment Expenses	0	0	0
Amortization of Policy Acquisition Costs	0	0	0
Other Operating Expenses	29,418	27,664	26,903
Net Written Premiums	$ 0	$ 0	$ 0

SCHEDULE IV - Reinsurance (Deta

SCHEDULE IV - Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Written Premiums	$ 1,103,994	$ 1,305,948	$ 1,027,222
Ceded to Other Companies Written Premiums	609,226	574,585	404,101
Assumed from Other Companies Written Premiums	153,006	164,787	139,551
Net written premiums	$ 647,774	$ 896,150	$ 762,672
Percentage of Amount Assumed to Net	23.60%	18.40%	18.30%
Excess and Surplus Lines
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Written Premiums	$ 699,143	$ 922,320	$ 656,538
Ceded to Other Companies Written Premiums	248,797	236,506	85,440
Assumed from Other Companies Written Premiums	0	0	0
Net written premiums	$ 450,346	$ 685,814	$ 571,098
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Specialty Admitted Insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Written Premiums	$ 404,851	$ 383,628	$ 370,684
Ceded to Other Companies Written Premiums	348,807	329,005	318,506
Assumed from Other Companies Written Premiums	3,840	4,014	3,662
Net written premiums	$ 59,884	$ 58,637	$ 55,840
Percentage of Amount Assumed to Net	6.40%	6.80%	6.60%
Casualty Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Written Premiums	$ 0	$ 0	$ 0
Ceded to Other Companies Written Premiums	11,622	9,074	155
Assumed from Other Companies Written Premiums	149,166	160,773	135,889
Net written premiums	$ 137,544	$ 151,699	$ 135,734
Percentage of Amount Assumed to Net	108.40%	106.00%	100.10%

SCHEDULE V - Valuation and Qu_2

SCHEDULE V - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 12,840	$ 3,948	$ 5,976
Additions Amounts Charged to Expense	3,318	11,421	2,454
Deductions Amounts Written Off or Disposals	(7,841)	(2,529)	(4,482)
Balance at End of Period	8,317	12,840	3,948
Allowance for Credit Losses on Premiums Receivable and Agents' Balances
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	5,659	3,948	2,757
Additions Amounts Charged to Expense	3,318	2,523	1,504
Deductions Amounts Written Off or Disposals	(660)	(812)	(313)
Balance at End of Period	8,317	5,659	3,948
Allowance for Credit Losses on Bank Loans
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	7,181	0	3,219
Additions Amounts Charged to Expense	0	8,898	950
Deductions Amounts Written Off or Disposals	(7,181)	(1,717)	(4,169)
Balance at End of Period	$ 0	$ 7,181	$ 0

SCHEDULE VI - Supplementary I_2

SCHEDULE VI - Supplementary Information Concerning Property Casualty Insurance Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]
Deferred policy acquisition costs	$ 62,953	$ 62,006	$ 54,450
Reserve for losses and loss adjustment expenses	2,192,080	2,045,506	1,661,459
Unearned premiums	630,371	524,377	386,473
Net earned premiums	606,806	823,746	815,398
Net investment income	73,368	75,652	61,256
Current year	386,341	603,094	582,604
Prior year	92,204	69,008	17,672
Total incurred losses and loss and adjustment expenses	478,545	672,102	600,276
Amortization of policy acquisition costs	75,578	83,893	111,103
Paid losses and loss adjustment expenses, net of reinsurance	469,945	488,729	396,013
Net written premiums	$ 647,774	$ 896,150	$ 762,672