James River (JRVR) 10-Q 7 Nov 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Nov. 05, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
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 Tax Identification Number	98-0585280
Entity Address, Address Line One	90 Pitts Bay Road
Entity Address, Address Line Two	2nd Floor
Entity Address, Address Line Three	Wellesley House
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Central Index Key	0001620459
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		30,405,422
Document Period End Date	Sep. 30, 2019
Amendment Flag	false
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2019

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Invested assets:
Fixed maturity securities, available-for-sale, at fair value (amortized cost: 2019 – $1,338,131; 2018 – $1,199,409)	$ 1,377,323	$ 1,184,202
Equity securities, at fair value (cost: 2019 – $78,906; 2018 – $77,152)	88,840	78,385
Bank loan participations held-for-investment, at amortized cost, net of allowance	249,907	260,972
Short-term investments	49,884	81,966
Other invested assets	65,864	72,321
Total invested assets	1,831,818	1,677,846
Cash and cash equivalents	256,302	172,457
Accrued investment income	13,603	11,110
Premiums receivable and agents’ balances, net	360,587	307,899
Reinsurance recoverable on unpaid losses	614,827	467,371
Reinsurance recoverable on paid losses	40,822	18,344
Prepaid reinsurance premiums	167,338	112,498
Deferred policy acquisition costs	60,970	54,450
Intangible assets, net	37,090	37,537
Goodwill	181,831	181,831
Other assets	95,728	95,433
Total assets	3,660,916	3,136,776
Liabilities:
Reserve for losses and loss adjustment expenses	1,941,307	1,661,459
Unearned premiums	510,109	386,473
Payables to reinsurers	131,093	61,662
Senior debt	98,300	118,300
Junior subordinated debt	104,055	104,055
Accrued expenses	57,637	51,792
Other liabilities	49,446	43,794
Total liabilities	2,891,947	2,427,535
Commitments and contingent liabilities
Shareholders’ equity:
Common Shares – 2019 and 2018: $0.0002 par value; 200,000,000 shares authorized; 30,401,270 and 29,988,460 shares issued and outstanding, respectively	6	6
Preferred Shares – 2019 and 2018: $0.00125 par value; 20,000,000 shares authorized; no shares issued and outstanding	0	0
Additional paid-in capital	655,998	645,310
Retained earnings	78,344	79,753
Accumulated other comprehensive income (loss)	34,621	(15,828)
Total shareholders’ equity	768,969	709,241
Total liabilities and shareholders’ equity	$ 3,660,916	$ 3,136,776

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Fixed maturity securities, available-for-sale, at amortized cost	$ 1,338,131	$ 1,199,409
Equity securities, at cost	$ 78,906	$ 77,152
Common stock, par value (in dollars per share)	$ 0.0002	$ 0.0002
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	30,401,270	29,988,460
Common stock, shares outstanding (in shares)	30,401,270	29,988,460
Preferred stock, par value (in dollars per share)	$ 0.00125	$ 0.00125
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of (Loss) Income and Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Gross written premiums	$ 388,228	$ 279,969	$ 1,095,565	$ 871,463
Ceded written premiums	(164,359)	(106,528)	(424,045)	(298,438)
Net written premiums	223,869	173,441	671,520	573,025
Change in net unearned premiums	(10,495)	31,249	(68,880)	40,817
Net earned premiums	213,374	204,690	602,640	613,842
Net investment income	17,878	16,410	54,844	45,801
Net realized and unrealized (losses) gains on investments	(2,357)	467	331	(407)
Other income	2,579	3,125	8,160	11,841
Total revenues	231,474	224,692	665,975	671,077
Expenses
Losses and loss adjustment expenses	214,084	150,387	501,064	448,754
Other operating expenses	41,692	49,180	132,287	155,714
Other expenses	372	(131)	1,055	(34)
Interest expense	2,594	2,991	8,086	8,459
Amortization of intangible assets	149	149	447	447
Total expenses	258,891	202,576	642,939	613,340
(Loss) income before taxes	(27,417)	22,116	23,036	57,737
Income tax (benefit) expense	(2,250)	2,535	5,168	5,539
Net (loss) income	(25,167)	19,581	17,868	52,198
Other comprehensive income (loss):
Net unrealized gains (losses), net of taxes of $638 and $3,949 in 2019 and $(407) and $(1,134) in 2018	9,457	(4,389)	50,449	(29,494)
Total comprehensive (loss) income	$ (15,710)	$ 15,192	$ 68,317	$ 22,704
Per share data:
Basic earnings (loss) per share (in dollars per share)	$ (0.83)	$ 0.65	$ 0.59	$ 1.75
Diluted earnings (loss) per share (in dollars per share)	(0.83)	0.64	0.58	1.72
Dividend declared per share (in dollars per share)	$ 0.30	$ 0.30	$ 0.90	$ 0.90
Weighted-average common shares outstanding:
Basic (in shares)	30,382,105	29,935,216	30,230,490	29,861,467
Diluted (in shares)	30,382,105	30,380,145	30,659,389	30,290,183

Condensed Consolidated Statem_2

Condensed Consolidated Statements of (Loss) Income and Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Tax on net unrealized gains (losses)	$ 638	$ (407)	$ 3,949	$ (1,134)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Shares	Preferred Shares	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2017		29,696,682
Balance at Dec. 31, 2017	$ 694,699	$ 6	$ 0	$ 636,149	$ 48,198	$ 10,346
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	52,198				52,198
Other comprehensive income (loss)	(29,494)					(29,494)
Dividends	(27,189)				(27,189)
Exercise of stock options (in shares)		210,134
Exercise of stock options	3,175			3,175
Vesting of RSUs (in shares)		43,304
Vesting of RSUs	(777)			(777)
Compensation expense under share incentive plans	4,796			4,796
Balance (in shares) at Sep. 30, 2018		29,950,120
Balance at Sep. 30, 2018	697,408	$ 6	0	643,343	77,178	(23,119)
Balance (in shares) at Jun. 30, 2018		29,917,821
Balance at Jun. 30, 2018	689,243	$ 6	0	641,290	66,677	(18,730)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	19,581				19,581
Other comprehensive income (loss)	(4,389)					(4,389)
Dividends	(9,080)				(9,080)
Exercise of stock options (in shares)		32,299
Exercise of stock options	372			372
Compensation expense under share incentive plans	1,681			1,681
Balance (in shares) at Sep. 30, 2018		29,950,120
Balance at Sep. 30, 2018	$ 697,408	$ 6	0	643,343	77,178	(23,119)
Balance (in shares) at Dec. 31, 2018	29,988,460	29,988,460
Balance at Dec. 31, 2018	$ 709,241	$ 6	0	645,310	79,753	(15,828)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	17,868				17,868
Other comprehensive income (loss)	50,449					50,449
Dividends	(27,557)				(27,557)
Exercise of stock options (in shares)		336,533
Exercise of stock options	6,799			6,799
Vesting of RSUs (in shares)		76,277
Vesting of RSUs	(1,374)			(1,374)
Compensation expense under share incentive plans	$ 5,263			5,263
Balance (in shares) at Sep. 30, 2019	30,401,270	30,401,270
Balance at Sep. 30, 2019	$ 768,969	$ 6	0	655,998	78,344	34,621
Balance (in shares) at Jun. 30, 2019		30,330,675
Balance at Jun. 30, 2019	791,050	$ 6	0	653,151	112,729	25,164
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(25,167)				(25,167)
Other comprehensive income (loss)	9,457					9,457
Dividends	(9,218)				(9,218)
Exercise of stock options (in shares)		70,595
Exercise of stock options	1,068			1,068
Compensation expense under share incentive plans	$ 1,779			1,779
Balance (in shares) at Sep. 30, 2019	30,401,270	30,401,270
Balance at Sep. 30, 2019	$ 768,969	$ 6	$ 0	$ 655,998	$ 78,344	$ 34,621

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net cash provided by operating activities	$ 213,787	$ 251,913
Securities available-for-sale:
Purchases – fixed maturity securities	(327,725)	(367,279)
Sales – fixed maturity securities	102,030	82,498
Maturities and calls – fixed maturity securities	85,921	113,980
Purchases – equity securities	(4,975)	(6,274)
Sales – equity securities	3,131	3,180
Bank loan participations:
Purchases	(73,102)	(165,878)
Sales	41,707	98,739
Maturities	34,303	43,139
Other invested assets:
Purchases	0	(6,993)
Return of capital	1,477	260
Redemptions	7,016	0
Short-term investments, net	32,082	(3,415)
Securities receivable or payable, net	10,673	3,064
Purchases of property and equipment	(442)	(595)
Net cash used in investing activities	(87,904)	(205,574)
Financing activities
Senior debt repayment	(20,000)	0
Dividends paid	(27,463)	(27,024)
Issuance of common shares under equity incentive plans	7,961	4,296
Common share repurchases	(2,536)	(1,898)
Other financing activities	0	(791)
Net cash used in financing activities	(42,038)	(25,417)
Change in cash and cash equivalents	83,845	20,922
Cash and cash equivalents at beginning of period	172,457	163,495
Cash and cash equivalents at end of period	256,302	184,417
Supplemental information
Interest paid	$ 9,510	$ 8,380

Accounting Policies

Accounting Policies	9 Months Ended
	Sep. 30, 2019
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.”). JRG Holdings 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 is an Ohio domiciled excess and surplus lines insurance company that, with its wholly-owned insurance subsidiary, James River Casualty Company, a Virginia domiciled 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 and its subsidiaries 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 The accompanying condensed consolidated financial statements and notes have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and do not contain all of the information and footnotes required by U.S. GAAP for complete financial statements. The condensed consolidated financial statements include the results of the Company and its subsidiaries from their respective dates of inception or acquisition, as applicable. Readers are urged to review the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 for a more complete description of the Company’s business and accounting policies. In the opinion of management, all adjustments necessary for a fair presentation of the condensed consolidated financial statements have been included. Such adjustments consist only of normal recurring items. Interim results are not necessarily indicative of results of operations for the full year. The consolidated balance sheet as of December 31, 2018 was derived from the Company’s audited annual consolidated financial statements. Intercompany transactions and balances have been eliminated. Estimates and Assumptions Preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying disclosures. Those estimates are inherently subject to change, and actual results may ultimately differ from those estimates. 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 the 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 condensed 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 $31.6 million and $29.8 million as of September 30, 2019 and December 31, 2018 , respectively, representing the Company’s maximum exposure to loss. Income Tax Expense Our effective tax rate fluctuates from period to period based on the relative mix of income reported by country and the respective tax rates imposed by each tax jurisdiction. For the nine months ended September 30, 2019 and 2018 , our U.S. federal income tax expense was 22.4% and 9.6% of income before taxes, respectively. For U.S.-sourced income, the Company’s U.S. federal income tax expense differs from the amounts computed by applying the federal statutory income tax rate to income before taxes due primarily to interest income on tax-advantaged state and municipal securities, dividends received income, and excess tax benefits on share based compensation. The effective tax rate for the nine months ended September 30, 2019 was elevated due to changes in reserve estimates between accident years in the commercial auto business, and the related impact on the mix of income reported by country. 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 the Tax Cuts and Jobs Act of 2017 ("TCJA"). The ASU allows for the option to reclassify the stranded tax effects resulting from the implementation of the TCJA 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 in connection with the Company's adoption of this ASU. Adopted Accounting Standards Effective January 1, 2019, the Company adopted ASU 2016-02, Leases (Topic 842) . This update requires the recognition of a right-of-use asset and a corresponding lease liability, discounted to the present value, for all leases that extend beyond 12 months. The Company adopted the new standard using a modified retrospective transition method, applying the transition provisions at the beginning of the period of adoption. The Company elected the package of practical expedients permitted under the transition guidance within the new standard and did not elect to use hindsight in determining the lease term. Upon adoption of the new standard, 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 recorded right-of-use assets of $17.2 million and lease liabilities of $17.8 million at adoption of the new standard associated with operating leases for office space in Bermuda, North Carolina, Virginia, Arizona, and Georgia. The new standard did not materially impact the Company's results of operations, earnings per share, or cash flows, and did not impact compliance under the covenants of our current credit agreements. At September 30, 2019 , right-of-use assets and lease liabilities were $16.2 million and $17.1 million , respectively. Operating lease costs were $1.3 million and $3.8 million in the three and nine months ended September 30, 2019 , respectively, compared to $1.3 million and $3.5 million in the respective prior year periods. The weighted-average discount rate and weighted average remaining lease term for operating leases was 4.3% and 5.5 years , respectively, as of September 30, 2019 . The table below summarizes maturities of the Company’s operating lease liabilities as of September 30, 2019 , which reconciles to total lease liabilities included in other liabilities on the Company’s condensed consolidated balance sheet: Years ending December 31, (in thousands) 2019 $ 959 2020 3,680 2021 3,491 2022 3,293 2023 3,099 Thereafter 4,706 Total lease payments 19,228 Less imputed interest (2,159 ) Total operating lease liabilities $ 17,069 Prospective Accounting Standards In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Current GAAP requires the recognition of credit losses when it is probable a loss has been incurred. The update will require 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 will also be 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. This ASU is effective for annual and interim reporting periods beginning after December 15, 2019. The Company plans to adopt the ASU on January 1, 2020 using the modified-retrospective approach, by which a cumulative-effect adjustment will be made to retained earnings as of the date of adoption. The Company is finalizing its implementation process for the adoption of this ASU and the evaluation of what effects the new standard will have on the Company’s financial statements. This ASU will have the greatest impact on our portfolio of bank loan participations and on our allowance for uncollectible reinsurance balances. In connection with the adoption of this ASU, we expect to elect the fair value option in accounting for bank loan participations effective January 1, 2020. We also expect to use the targeted transition relief offered by ASU 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief to also 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 will be measured at fair value, and changes in unrealized gains and losses in bank loan participations will be reported in our income statement as net realized and unrealized gains (losses) on investments. Upon adoption of this ASU, we anticipate that we will establish an allowance for uncollectible reinsurance balances, but because we purchase reinsurance from financially strong reinsurers or we have collateral securing the recoverables, we do not expect that the effect of adoption will be material to our financial position.

Investments

Investments	9 Months Ended
	Sep. 30, 2019
Investments [Abstract]
Investments	Investments The Company’s available-for-sale fixed maturity securities are summarized as follows: Cost or Gross Gross Fair (in thousands) September 30, 2019 Fixed maturity securities: State and municipal $ 145,016 $ 9,460 $ (89 ) $ 154,387 Residential mortgage-backed 245,315 2,849 (951 ) 247,213 Corporate 603,524 21,887 (231 ) 625,180 Commercial mortgage and asset-backed 230,417 5,221 (434 ) 235,204 U.S. Treasury securities and obligations guaranteed by the U.S. government 111,834 1,538 (40 ) 113,332 Redeemable preferred stock 2,025 — (18 ) 2,007 Total fixed maturity securities, available-for-sale $ 1,338,131 $ 40,955 $ (1,763 ) $ 1,377,323 December 31, 2018 Fixed maturity securities: State and municipal $ 147,160 $ 3,422 $ (1,287 ) $ 149,295 Residential mortgage-backed 208,869 577 (5,337 ) 204,109 Corporate 534,024 1,516 (10,772 ) 524,768 Commercial mortgage and asset-backed 199,528 310 (2,813 ) 197,025 U.S. Treasury securities and obligations guaranteed by the U.S. government 107,803 235 (845 ) 107,193 Redeemable preferred stock 2,025 — (213 ) 1,812 Total fixed maturity securities, available-for-sale $ 1,199,409 $ 6,060 $ (21,267 ) $ 1,184,202 The amortized cost and fair value of available-for-sale investments in fixed maturity securities at September 30, 2019 are summarized, by contractual maturity, as follows: Cost or Fair (in thousands) One year or less $ 76,678 $ 77,005 After one year through five years 459,889 470,945 After five years through ten years 205,048 214,952 After ten years 118,759 129,997 Residential mortgage-backed 245,315 247,213 Commercial mortgage and asset-backed 230,417 235,204 Redeemable preferred stock 2,025 2,007 Total $ 1,338,131 $ 1,377,323 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) September 30, 2019 Fixed maturity securities: State and municipal $ 14,250 $ (87 ) $ 667 $ (2 ) $ 14,917 $ (89 ) Residential mortgage-backed 21,623 (34 ) 60,059 (917 ) 81,682 (951 ) Corporate 17,310 (149 ) 29,627 (82 ) 46,937 (231 ) Commercial mortgage and asset-backed 18,225 (70 ) 52,823 (364 ) 71,048 (434 ) U.S. Treasury securities and obligations guaranteed by the U.S. government 105 (1 ) 16,030 (39 ) 16,135 (40 ) Redeemable preferred stock 2,007 (18 ) — — 2,007 (18 ) Total fixed maturity securities, available-for-sale $ 73,520 $ (359 ) $ 159,206 $ (1,404 ) $ 232,726 $ (1,763 ) December 31, 2018 Fixed maturity securities: State and municipal $ 19,733 $ (284 ) $ 47,018 $ (1,003 ) $ 66,751 $ (1,287 ) Residential mortgage-backed 49,180 (743 ) 105,778 (4,594 ) 154,958 (5,337 ) Corporate 243,384 (5,089 ) 155,902 (5,683 ) 399,286 (10,772 ) Commercial mortgage and asset-backed 106,423 (1,229 ) 51,805 (1,584 ) 158,228 (2,813 ) U.S. Treasury securities and obligations guaranteed by the U.S. government 17,618 (51 ) 54,201 (794 ) 71,819 (845 ) Redeemable preferred stock 1,812 (213 ) — — 1,812 (213 ) Total fixed maturity securities, available-for-sale $ 438,150 $ (7,609 ) $ 414,704 $ (13,658 ) $ 852,854 $ (21,267 ) The Company held securities of 76 issuers that were in an unrealized loss position at September 30, 2019 with a total fair value of $232.7 million and gross unrealized losses of $1.8 million . None of the fixed maturity securities with unrealized losses has ever missed, or been delinquent on, a scheduled principal or interest payment. At September 30, 2019 , 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. Fixed maturity securities with ratings below investment grade by Standard & Poor’s or another nationally recognized rating agency at September 30, 2019 had an aggregate fair value of $5.3 million and an aggregate net unrealized gain of $79,000 . At March 31, 2019, management concluded that three fixed maturity securities from one issuer that we intended to sell at a loss in the second quarter were impaired. The Company recorded impairment losses on these securities of $271,000 in the three months ended March 31, 2019. Management concluded that none of the fixed maturity securities with an unrealized loss at September 30, 2019 or December 31, 2018 had experienced an other-than-temporary impairment. For fixed maturity securities available-for-sale that are not other-than-temporarily impaired at September 30, 2019 , 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 five loans from four issuers in the Company's bank loan portfolio were impaired at September 30, 2019 . At September 30, 2019 , the impaired loans had a carrying value of $6.4 million , unpaid principal of $12.3 million , and an allowance for credit losses of $5.9 million , $4.2 million of which related to two loans from one issuer who is 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 September 30, 2018 or December 31, 2018 . The aggregate allowance for credit losses on impaired loans was $3.2 million at December 31, 2017 . At December 31, 2017 , the Company held a participation in a loan with unpaid principal of $807,000 issued by a company that produces and supplies power to Puerto Rico through a power purchase agreement with Puerto Rico Electric Power Authority, a public corporation and governmental agency of the Commonwealth of Puerto Rico. Management concluded that an allowance for credit losses should be established on the loan at December 31, 2017 to reduce its carrying value to $0 . In the first quarter of 2018, the full outstanding principal on the loan was repaid and the Company recognized a realized gain of $807,000 on the repayment. Bank loan participations generally provide a higher yield than our portfolio of fixed maturities and 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. 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. 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 September 30, 2019 or December 31, 2018 . The allowance for credit losses is maintained at a level believed adequate by management to absorb estimated probable credit losses. Management’s periodic evaluation of the adequacy of the allowance is based on consultations and a dvice of the Company’s independent investment manager, known and inherent risks in the portfolio, adverse situations that may affect the borrower’s ability to repay, the estimated value of any underlying collateral, current economic conditions, and other relevant factors. When an observable market price for a loan is available, the Company has recorded an allowance equal to the difference between the fair value and the amortized cost of bank loans that it has determined to be impaired as a practical expedient for an estimate of probable future cash flows to be collected on those bank loans. Bank loans are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. The average recorded investment in impaired bank loans was $3.2 million and $2.6 million during the nine months ended September 30, 2019 and 2018 , respectively. Investment income of $23,000 and $125,000 , respectively, was recognized during the time within those periods that the loans were impaired. The Company recorded net realized investment losses of $5.9 million and $7.7 million in the three and nine months ended September 30, 2019 , respectively, for changes in the fair value of impaired bank loans (net realized investment gains of $42,000 and net realized investment losses of $851,000 in three and nine months ended September 30, 2018 respectively). The Company’s net realized and unrealized gains and losses on investments are summarized as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Fixed maturity securities: Gross realized gains $ 445 $ 12 $ 1,033 $ 394 Gross realized losses (9 ) (225 ) (494 ) (700 ) 436 (213 ) 539 (306 ) Bank loan participations: Gross realized gains 79 186 229 1,766 Gross realized losses (6,056 ) — (9,056 ) (1,106 ) (5,977 ) 186 (8,827 ) 660 Equity securities: Gross realized gains 11 — 11 — Gross realized losses (78 ) — (96 ) (62 ) Changes in fair values of equity securities 3,251 494 8,700 (695 ) 3,184 494 8,615 (757 ) Short-term investments and other: Gross realized gains 1 — 5 — Gross realized losses (1 ) — (1 ) (4 ) — — 4 (4 ) Total $ (2,357 ) $ 467 $ 331 $ (407 ) Realized investment gains or losses are determined on a specific identification basis. 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 September 30, December 31, Three Months Ended Nine Months Ended 2019 2018 2019 2018 2019 2018 (in thousands) Renewable energy LLCs (a) $ 31,618 $ 29,795 $ 1,602 $ 329 $ 2,510 $ 2,070 Renewable energy notes receivable ( b) 8,750 8,750 328 328 984 954 Limited partnerships (c) 20,996 29,276 (631 ) 989 2,166 2,307 Bank holding companies (d) 4,500 4,500 85 85 257 257 Total other invested assets $ 65,864 $ 72,321 $ 1,384 $ 1,731 $ 5,917 $ 5,588 (a) The Company’s Corporate and Other segment owns equity interests ranging from 2.6% to 32.2% 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 one of our directors serves as an officer, and the Company’s Chairman and Chief Executive Officer ("CEO") 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 $687,000 and $2.8 million in the nine months ended September 30, 2019 and 2018 , respectively. (b) The Company's Corporate and Other segment has invested in notes receivable for renewable energy projects. At September 30, 2019 , the Company holds an $8.8 million note issued by an entity for which one of our directors serves as an officer . Interest on the note, which matures in 2021, is fixed at 15.0% . Interest income on the note was $328,000 and $984,000 for the three and nine months ended September 30, 2019 , respectively ( $328,000 and $954,000 for the three and nine months ended September 30, 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 f rom the partnerships is recognized under the equity method of accounting. The Company’s Corporate and Other segment held an investment in a limited partnership with a carrying value of $3.3 million at September 30, 2019 . The Company recognized investment income of $182,000 and $474,000 on the investment for the nine months ended September 30, 2019 and 2018 , respectively. The Company’s Excess and Surplus Lines segment holds investments in limited partnerships of $17.7 million at September 30, 2019 . Investment income of $2.0 million and $1.8 million was recognized on the investments for the nine months ended September 30, 2019 and 2018 , respectively. At September 30, 2019 , the Company’s Excess and Surplus Lines segment has outstanding commitments to invest another $625,000 in these limited partnerships. (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 Chairman and CEO 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 holder of the subordinated notes (the "Bank Holding Company"). Interest on the notes, which mature on August 12, 2023, is fixed at 7.6% per annum. Interest income on the notes was $257,000 in both the nine months ended September 30, 2019 and 2018 , respectively. At September 30, 2019 and December 31, 2018 , the Company held an investment in a CLO where one of the underlying loans was issued by the Bank Holding Company. The investment, with a carrying value of $3.4 million at September 30, 2019 , is classified as an available-for-sale fixed maturity.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2019
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. Goodwill resulting from the Merger was $181.8 million at September 30, 2019 and December 31, 2018 . The gross carrying amounts and accumulated amortization for each major specifically identifiable intangible asset class were as follows: September 30, 2019 December 31, 2018 Life Gross Accumulated Gross Accumulated ($ in thousands) Intangible Assets 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 5,685 11,611 5,238 Identifiable intangible assets subject to amortization 11,611 5,685 11,611 5,238 $ 42,775 $ 5,685 $ 42,775 $ 5,238

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share	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 condensed consolidated financial statements: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands, except share and per share amounts) Net (loss) income to shareholders $ (25,167 ) $ 19,581 $ 17,868 $ 52,198 Weighted average common shares outstanding: Basic 30,382,105 29,935,216 30,230,490 29,861,467 Common share equivalents — 444,929 428,899 428,716 Diluted 30,382,105 30,380,145 30,659,389 30,290,183 Earnings per share: Basic $ (0.83 ) $ 0.65 $ 0.59 $ 1.75 Common share equivalents — (0.01 ) (0.01 ) (0.03 ) Diluted $ (0.83 ) $ 0.64 $ 0.58 $ 1.72 Common share equivalents relate to our outstanding equity awards (stock options and restricted share units ("RSUs")). For the three months ended September 30, 2019 , common share equivalents of 431,137 were excluded from the calculation of diluted earnings per share as a net loss for the three months ended September 30, 2019 made the effects of all common share equivalents anti-dilutive. For the nine months ended September 30, 2019 , all common share equivalents are dilutive. For the three and nine months ended September 30, 2018 , common share equivalents of 173,758 and 182,870 shares, respectively, were excluded from the calculations of diluted earnings per share as their effects were anti-dilutive.

Reserve for Losses and Loss Adj

Reserve for Losses and Loss Adjustment Expenses	9 Months Ended
	Sep. 30, 2019
Liability for Claims and Claims Adjustment Expense [Abstract]
Reserve for Losses and Loss Adjustment Expenses	Reserve for Losses and Loss Adjustment Expenses 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: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Reserve for losses and loss adjustment expenses net of reinsurance recoverables at beginning of period $ 1,237,930 $ 1,092,818 $ 1,194,088 $ 989,825 Add: Incurred losses and loss adjustment expenses net of reinsurance: Current year 157,113 138,168 440,810 436,921 Prior years 56,971 12,219 60,254 11,833 Total incurred losses and loss and adjustment expenses 214,084 150,387 501,064 448,754 Deduct: Loss and loss adjustment expense payments net of reinsurance: Current year 21,021 25,149 46,275 57,903 Prior years 104,513 72,695 322,397 235,315 Total loss and loss adjustment expense payments 125,534 97,844 368,672 293,218 Reserve for losses and loss adjustment expenses net of reinsurance recoverables at end of period 1,326,480 1,145,361 1,326,480 1,145,361 Add: Reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period 614,827 424,400 614,827 424,400 Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period $ 1,941,307 $ 1,569,761 $ 1,941,307 $ 1,569,761 The Company experienced $57.0 million of adverse reserve development in the three months ended September 30, 2019 on the reserve for losses and loss adjustment expenses held at December 31, 2018 . This reserve development included $50.0 million of adverse development in the Excess and Surplus Lines segment primarily related to the 2016 and 2017 accident years for the commercial auto business. The Specialty Admitted Insurance segment experienced $1.0 million of favorable development due to favorable development in the workers' compensation business for prior accident years. The Company also experienced $7.9 million of adverse development in the Casualty Reinsurance segment due to higher than expected levels of reported losses in the quarter. The Company experienced $12.2 million of adverse reserve development in the three months ended September 30, 2018 on the reserve for losses and loss adjustment expenses held at December 31, 2017 . This reserve development included $10.4 million of adverse development in the Excess and Surplus Lines segment, primarily from adverse development in commercial auto business which was partially offset by $3.0 million of favorable development on the property catastrophe losses from the September 2017 storms. The Specialty Admitted Insurance segment experienced $833,000 of favorable development, primarily due to favorable development in the workers' compensation business for prior accident years. The Company also experienced $2.7 million of adverse development in the Casualty Reinsurance segment. The Company experienced $60.3 million of adverse reserve development in the nine months ended September 30, 2019 on the reserve for losses and loss adjustment expenses held at December 31, 2018 . This reserve development included $51.2 million of adverse development in the Excess and Surplus Lines segment primarily related to the 2016 and 2017 accident years for the commercial auto business. The Specialty Admitted Insurance segment experienced $4.3 million of favorable development due to favorable development in the workers' compensation business for prior accident years. The Company also experienced $13.3 million of adverse development in the Casualty Reinsurance segment due to higher than expected levels of reported losses in the nine months ended September 30, 2019 . The Company experienced $11.8 million of adverse reserve development in the nine months ended September 30, 2018 on the reserve for losses and loss adjustment expenses held at December 31, 2017 . This reserve development included $9.2 million of adverse development in the Excess and Surplus Lines segment, primarily from adverse development in commercial auto business which was partially offset by favorable development in other core Excess and Surplus Lines including $4.9 million of favorable development on the property catastrophe losses from the September 2017 storms. The Specialty Admitted Insurance segment experienced $2.3 million of favorable development, primarily due to favorable development in the workers' compensation business for prior accident years, partially offset by adverse development on certain terminated program business. The Company also experienced $4.9 million of adverse development in the Casualty Reinsurance segment.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2019
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): Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Unrealized gains (losses) arising during the period, before U.S. income taxes $ 10,531 $ (5,009 ) $ 54,937 $ (30,934 ) U.S. income taxes (690 ) 425 (4,045 ) 1,124 Unrealized gains (losses) arising during the period, net of U.S. income taxes 9,841 (4,584 ) 50,892 (29,810 ) Less reclassification adjustment: Net realized investment gains (losses) 436 (213 ) 539 (306 ) U.S. income taxes (52 ) 18 (96 ) (10 ) Reclassification adjustment for investment gains (losses) realized in net income 384 (195 ) 443 (316 ) Other comprehensive income (loss) $ 9,457 $ (4,389 ) $ 50,449 $ (29,494 ) In addition to the $436,000 and $539,000 of net realized investment gains on available-for-sale fixed maturity securities for the three and nine months ended September 30, 2019 , respectively ( $213,000 and $306,000 of net realized investment losses in the respective prior year periods), the Company also recognized $6.0 million and $8.8 million of net realized investment losses in the respective periods on its investments in bank loan participations ( $186,000 and $660,000 of net realized investment gains in the respective prior year periods), and $3.3 million and $8.7 million of net realized gains in the respective periods for the change in fair values of equity securities ( $494,000 of net realized gains and $695,000 of net realized losses in the respective prior year periods).

Contingent Liabilities

Contingent Liabilities	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities	Contingent Liabilities The Company is a party to various lawsuits 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. JRG Re has 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, $48.2 million of letters of credit were issued through September 30, 2019 which were secured by deposits of $60.9 million . Under a $102.5 million facility, $64.1 million of letters of credit were issued through September 30, 2019 which were secured by deposits of $83.3 million . Under a $100.0 million facility, $5.3 million of letters of credit were issued through September 30, 2019 which were secured by deposits of $10.9 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 $299.1 million at September 30, 2019 . The Company is a party to a set of insurance contracts with an insured group of companies under which the Company pays losses and loss adjustment expenses on the contract. The Company has indemnity agreements with this group of insured parties (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 the insured parties and other expenses incurred by the Company. The insured parties are 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 agreement, 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 currently provided through a collateral trust arrangement established in favor of the Company by a captive insurance company affiliate of the insured group. At September 30, 2019 , the cash equivalent collateral held in the collateral trust arrangement was approximately $1,168.9 million . 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. On October 9, 2019, the Company withdrew $1,170.7 million from the collateral trust arrangement. See Note 12 for additional information regarding the withdrawal of the collateral.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information The Company has four reportable segments: the Excess and Surplus Lines segment, the Specialty Admitted Insurance segment, the Casualty Reinsurance segment, and the Corporate and Other segment. Segment profit (loss) is measured by underwriting profit (loss), which is generally defined as net earned premiums less loss and loss adjustment expenses and other operating expenses of the operating segments. Gross fee income of the Excess and Surplus Lines segment is included in that segment’s underwriting profit. Gross fee income of $2.2 million and $3.0 million was included in underwriting profit for the three months ended September 30, 2019 and 2018 , respectively ( $7.1 million and $11.5 million for the nine months ended September 30, 2019 and 2018 , respectively). Segment results are reported prior to the effects of intercompany reinsurance agreements among the Company’s insurance subsidiaries. The following table summarizes the Company’s segment results: Excess and Surplus Lines Specialty Admitted Insurance Casualty Reinsurance Corporate and Other Total (in thousands) Three Months Ended September 30, 2019 Gross written premiums $ 241,045 $ 100,459 $ 46,724 $ — $ 388,228 Net earned premiums 164,759 14,242 34,373 — 213,374 Underwriting (loss) profit of insurance segments (29,351 ) 837 (4,288 ) — (32,802 ) Net investment income 3,467 976 11,717 1,718 17,878 Interest expense — — — 2,594 2,594 Segment revenues 170,734 16,493 42,403 1,844 231,474 Segment goodwill 181,831 — — — 181,831 Segment assets 1,186,094 773,677 1,631,569 69,576 3,660,916 Three Months Ended September 30, 2018 Gross written premiums $ 157,237 $ 98,607 $ 24,125 $ — $ 279,969 Net earned premiums 141,529 13,898 49,263 — 204,690 Underwriting profit of insurance segments 11,302 1,769 1,576 — 14,647 Net investment income 4,542 825 10,031 1,012 16,410 Interest expense — — — 2,991 2,991 Segment revenues 149,807 14,400 59,416 1,069 224,692 Segment goodwill 181,831 — — — 181,831 Segment assets 929,408 630,982 1,393,721 81,323 3,035,434 Excess and Specialty Casualty Corporate Total (in thousands) Nine Months Ended September 30, 2019 Gross written premiums $ 687,871 $ 292,884 $ 114,810 $ — $ 1,095,565 Net earned premiums 457,352 39,688 105,600 — 602,640 Underwriting (loss) profit of insurance segments (439 ) 3,758 (4,061 ) — (742 ) Net investment income 13,240 2,791 34,875 3,938 54,844 Interest expense — — — 8,086 8,086 Segment revenues 481,745 45,169 134,731 4,330 665,975 Segment goodwill 181,831 — — — 181,831 Segment assets 1,186,094 773,677 1,631,569 69,576 3,660,916 Nine Months Ended September 30, 2018 Gross written premiums $ 490,121 $ 283,108 $ 98,234 $ — $ 871,463 Net earned premiums 410,627 41,504 161,711 — 613,842 Underwriting profit of insurance segments 32,718 4,380 5,049 — 42,147 Net investment income 11,934 2,375 27,710 3,782 45,801 Interest expense — — — 8,459 8,459 Segment revenues 434,146 43,791 189,196 3,944 671,077 Segment goodwill 181,831 — — — 181,831 Segment assets 929,408 630,982 1,393,721 81,323 3,035,434 The following table reconciles the underwriting profit (loss) of the operating segments by individual segment to consolidated income before taxes: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Underwriting (loss) profit of the insurance segments: Excess and Surplus Lines $ (29,351 ) $ 11,302 $ (439 ) $ 32,718 Specialty Admitted Insurance 837 1,769 3,758 4,380 Casualty Reinsurance (4,288 ) 1,576 (4,061 ) 5,049 Total underwriting (loss) profit of insurance segments (32,802 ) 14,647 (742 ) 42,147 Other operating expenses of the Corporate and Other segment (7,302 ) (6,526 ) (22,641 ) (21,264 ) Underwriting (loss) profit (40,104 ) 8,121 (23,383 ) 20,883 Net investment income 17,878 16,410 54,844 45,801 Net realized and unrealized (losses) gains on investments (2,357 ) 467 331 (407 ) Amortization of intangible assets (149 ) (149 ) (447 ) (447 ) Other income and expenses (91 ) 258 (223 ) 366 Interest expense (2,594 ) (2,991 ) (8,086 ) (8,459 ) (Loss) income before taxes $ (27,417 ) $ 22,116 $ 23,036 $ 57,737

Other Operating Expenses and Ot

Other Operating Expenses and Other Expenses	9 Months Ended
	Sep. 30, 2019
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: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Amortization of policy acquisition costs $ 21,258 $ 27,511 $ 63,029 $ 86,381 Other underwriting expenses of the operating segments 13,132 15,143 46,617 48,069 Other operating expenses of the Corporate and Other segment 7,302 6,526 22,641 21,264 Total $ 41,692 $ 49,180 $ 132,287 $ 155,714 Other expenses of $372,000 and $1.1 million for the three and nine months ended September 30, 2019 consist of employee severance costs. Other expenses of $(131,000) and $(34,000) for the three and nine months ended September 30, 2018 , respectively, included employee severance, legal, and other professional services associated with the Company's May 2018 secondary offering, and depreciation expense related to a leased building that the Company was previously deemed to own for accounting purposes, offset by rental income on the building.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
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. To measure fair value, the Company obtains quoted market prices for its investment securities from its outside investment managers. If a quoted market price is not available, the Company uses prices of similar 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) 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, 2017. The Company reviews fair value prices provided by its outside 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 September 30, 2019 are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ — $ 154,387 $ — $ 154,387 Residential mortgage-backed — 247,213 — 247,213 Corporate — 625,180 — 625,180 Commercial mortgage and asset-backed — 235,204 — 235,204 U.S. Treasury securities and obligations guaranteed by the U.S. government 112,826 506 — 113,332 Redeemable preferred stock — 2,007 — 2,007 Total fixed maturity securities, available-for-sale $ 112,826 $ 1,264,497 $ — $ 1,377,323 Equity securities: Preferred stock — 69,552 — 69,552 Common stock 15,065 4,179 44 19,288 Total equity securities $ 15,065 $ 73,731 $ 44 $ 88,840 Short-term investments $ — $ 49,884 $ — $ 49,884 Assets measured at fair value on a recurring basis as of December 31, 2018 are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ — $ 149,295 $ — $ 149,295 Residential mortgage-backed — 204,109 — 204,109 Corporate — 524,768 — 524,768 Commercial mortgage and asset-backed — 192,797 4,228 197,025 U.S. Treasury securities and obligations guaranteed by the U.S. government 106,651 542 — 107,193 Redeemable preferred stock — 1,812 — 1,812 Total fixed maturity securities, available-for-sale $ 106,651 $ 1,073,323 $ 4,228 $ 1,184,202 Equity securities: Preferred stock — 60,740 — 60,740 Common stock 16,674 757 214 17,645 Total equity securities $ 16,674 $ 61,497 $ 214 $ 78,385 Short-term investments $ 1,250 $ 80,716 $ — $ 81,966 A reconciliation of the beginning and ending balances of available-for-sale fixed maturity securities and equity securities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is shown below: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands) (in thousands) Beginning balance $ 3,099 $ 4,680 $ 4,442 $ 4,680 Transfers out of Level 3 (3,010 ) — (7,238 ) — Transfers in to Level 3 — — 3,010 — Purchases — — — — Sales — — — — Maturities, calls and paydowns — (316 ) — (316 ) Amortization of discount — — — — Total gains or losses (realized/unrealized): Included in earnings (45 ) — (170 ) — Included in other comprehensive income — — — — Ending balance $ 44 $ 4,364 $ 44 $ 4,364 The Company held one available-for-sale fixed maturity 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 $4.2 million for the security at December 31, 2018 . A principal payment of $456,000 was received on the available-for-sale fixed maturity security in the three months ended March 31, 2019. The Company was able to obtain a quoted price from a pricing vendor for the available-for-sale fixed maturity security at March 31, 2019 and it was transferred to Level 2. In the three months ended June 30, 2019, one equity security was transferred from Level 1 to Level 3 as the security was no longer actively traded. In the three months ended September 30, 2019, one equity security was transferred from Level 3 to Level 2 as the Company was able to obtain a quoted price from a pricing vendor for the equity security at September 30, 2019. At September 30, 2019 and December 31, 2018 , the Company held one equity security 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 securities of $44,000 at September 30, 2019 and $214,000 at December 31, 2018 . There were no purchases or sales of Level 3 securities for the nine months ended September 30, 2019 or 2018 . There were no transfers involving Level 3 securities for the nine months ended September 30, 2018 . Transfers out of Level 3 occur when the Company is able to obtain reliable prices from pricing vendors for securities 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 to value the securities. There were no transfers between Level 1 and Level 2 during the nine months ended September 30, 2019 or 2018 . The Company recognizes transfers between levels at the beginning of the reporting period. The Company measures certain bank loan participations at fair value on a non-recurring basis during the year as part of the Company’s impairment evaluation when loans are determined by management to be impaired. Assets measured at fair value on a nonrecurring basis are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) September 30, 2019 Bank loan participations held-for-investment $ — $ — $ 6,361 $ 6,361 December 31, 2018 Bank loan participations held-for-investment $ — $ — $ — $ — Bank loan participations held-for-investment that were determined to be impaired were written down to their fair value of $6.4 million a t September 30, 2019 . Management concluded that none of the bank loan participations held-for-investment were impaired as of December 31, 2018 . 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. At September 30, 2019 and December 31, 2018 , there were no investments for which external sources were unavailable to determine fair value. The carrying values and fair values of financial instruments are summarized below: September 30, 2019 December 31, 2018 Carrying Fair Value Carrying Fair Value (in thousands) Assets Fixed maturity securities, available-for-sale $ 1,377,323 $ 1,377,323 $ 1,184,202 $ 1,184,202 Equity securities 88,840 88,840 78,385 78,385 Bank loan participations held-for-investment 249,907 242,628 260,972 250,697 Cash and cash equivalents 256,302 256,302 172,457 172,457 Short-term investments 49,884 49,884 81,966 81,966 Other invested assets – notes receivable 13,250 18,767 13,250 18,687 Liabilities Senior debt 98,300 101,256 118,300 118,317 Junior subordinated debt 104,055 125,008 104,055 117,057 The fair values of fixed maturity securities and equity securities 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 September 30, 2019 and December 31, 2018 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 September 30, 2019 and December 31, 2018 , respectively. The fair values of bank loan participations held-for-investment, senior debt, and junior subordinated debt at September 30, 2019 and December 31, 2018 were determined using inputs to the valuation methodology that are unobservable (Level 3).

Capital Stock and Equity Awards

Capital Stock and Equity Awards	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
Capital Stock and Equity Awards	Capital Stock and Equity Awards The Company issued 412,810 common shares in the nine months ended September 30, 2019 with 336,533 of the new shares related to stock option exercises and 76,277 of the new shares related to vesting of RSUs. The total common shares outstanding increased from 29,988,460 at December 31, 2018 to 30,401,270 at September 30, 2019 . The Company declared the following dividends during the first nine months of 2019 and 2018: Date of Declaration Dividend per Common Share Payable to Shareholders of Record on Payment Date Total Amount 2019 February 20, 2019 $ 0.30 March 11, 2019 March 29, 2019 $ 9,146,357 April 30, 2019 0.30 June 10, 2019 June 28, 2019 9,204,804 July 30, 2019 0.30 September 16, 2019 September 30, 2019 9,230,801 $ 0.90 $ 27,581,962 2018 February 22, 2018 $ 0.30 March 12, 2018 March 30, 2018 $ 9,049,476 May 1, 2018 0.30 June 11, 2018 June 29, 2018 9,066,023 August 1, 2018 0.30 September 10, 2018 September 28, 2018 9,080,519 $ 0.90 $ 27,196,018 Included in the total dividends for the nine months ended September 30, 2019 and 2018 are $327,000 and $297,000 , respectively, of dividend equivalents on unvested RSUs. The balance of dividends payable on unvested RSUs was $651,000 at September 30, 2019 and $557,000 at December 31, 2018 . 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. Options are outstanding under the Legacy Plan; however, 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 September 30, 2019 , 1,575,359 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 September 30, 2019 , 108,594 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 in the applicable plans), and in the case of the 2014 LTIP for Good Reason (as defined in the applicable plans), at any time following a Change in Control (as defined in the applicable plans). Options The following table summarizes option activity: Nine Months Ended September 30, 2019 2018 Shares Weighted- Shares Weighted- Outstanding: Beginning of period 1,115,324 $ 29.02 1,479,236 $ 27.81 Granted — $ — — $ — Exercised (450,514 ) $ 26.68 (280,683 ) $ 21.03 Forfeited (12,058 ) $ 36.84 (42,215 ) $ 36.86 End of period 652,752 $ 30.50 1,156,338 $ 29.13 Exercisable, end of period 599,241 $ 29.44 841,763 $ 26.64 All of the outstanding options vest over three to four 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 weighted-average remaining contractual life of the options outstanding and options exercisable at September 30, 2019 was 3.2 years and 3.1 years , respectively. RSUs The following table summarizes RSU activity: Nine Months Ended September 30, 2019 2018 Shares Weighted- Shares Weighted- Unvested, beginning of period 300,142 $ 39.22 178,882 $ 37.93 Granted 197,078 $ 42.56 218,475 $ 39.75 Vested (111,212 ) $ 39.90 (63,191 ) $ 40.92 Forfeited (22,445 ) $ 41.32 (5,889 ) $ 40.81 Unvested, end of period 363,563 $ 40.69 328,277 $ 38.51 The vesting period of RSUs granted to employees range from one to five years and vest ratably over the respective vesting period, and the majority vest in three years . All RSUs granted to date to non-employee directors had a one year vesting period. The holders of RSUs are entitled to dividend equivalents. The dividend equivalents are settled in cash at the same time that the underlying RSUs vest and are subject to the same risk of forfeiture as the underlying shares. The fair value of the RSUs granted is based on the market price of the underlying shares at the date of grant. 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: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Share based compensation expense $ 1,779 $ 1,681 $ 5,263 $ 4,796 U.S. tax benefit on share based compensation expense 211 198 631 569 As of September 30, 2019 , the Company had $10.5 million of unrecognized share based compensation expense expected to be charged to earnings over a weighted-average period of 1.8 years .

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On October 8, 2019, the Company delivered a notice of early cancellation, effective December 31, 2019, of all insurance policies issued to its largest customer, Rasier LLC and its affiliates. All insurance policies related to this customer are included in the Company’s commercial auto line of business within its Excess and Surplus Lines segment, and a majority of the insurance policies were due to expire on February 29, 2020. In addition, as permitted under the indemnity agreements with this group of insured parties (non-insurance entities), the Company withdrew $1,170.7 million from the collateral trust arrangement that was established in favor of the Company by a captive insurance company affiliate of the insured group. The collateral funds may be used to reimburse the Company for a significant portion of the losses and loss adjustment expenses paid on behalf of the insured parties and other related expenses incurred by the Company to the extent not paid under the indemnity agreements. Amounts that may be recoverable under the indemnity agreement include, 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. These funds have been invested in short term U.S. government securities. On November 6, 2019, the Company received a letter from its largest customer requesting redeposit of the collateral withdrawn on October 9, 2019 plus interest. We believe the withdrawal of collateral funds was permitted by the applicable agreements, and we do not intend to redeposit the funds. On November 5, 2019 , the Board of Directors declared a cash dividend of $0.30 per common share. The dividend is payable on December 31, 2019 to shareholders of record on December 16, 2019 .

Accounting Policies (Policies)

Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements and notes have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and do not contain all of the information and footnotes required by U.S. GAAP for complete financial statements. The condensed consolidated financial statements include the results of the Company and its subsidiaries from their respective dates of inception or acquisition, as applicable. Readers are urged to review the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 for a more complete description of the Company’s business and accounting policies. In the opinion of management, all adjustments necessary for a fair presentation of the condensed consolidated financial statements have been included. Such adjustments consist only of normal recurring items. Interim results are not necessarily indicative of results of operations for the full year. The consolidated balance sheet as of December 31, 2018 was derived from the Company’s audited annual consolidated financial statements. Intercompany transactions and balances have been eliminated.
Estimates and Assumptions	Estimates and Assumptions Preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying disclosures. Those estimates are inherently subject to change, and actual results may ultimately differ from those estimates.
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 the 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.
Income Tax Expense	Income Tax Expense Our effective tax rate fluctuates from period to period based on the relative mix of income reported by country and the respective tax rates imposed by each tax jurisdiction. For the nine months ended September 30, 2019 and 2018 , our U.S. federal income tax expense was 22.4% and 9.6% of income before taxes, respectively. For U.S.-sourced income, the Company’s U.S. federal income tax expense differs from the amounts computed by applying the federal statutory income tax rate to income before taxes due primarily to interest income on tax-advantaged state and municipal securities, dividends received income, and excess tax benefits on share based compensation. The effective tax rate for the nine months ended September 30, 2019 was elevated due to changes in reserve estimates between accident years in the commercial auto business, and the related impact on the mix of income reported by country. 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.
Adopted and Prospective Accounting Standards	Adopted Accounting Standards Effective January 1, 2019, the Company adopted ASU 2016-02, Leases (Topic 842) . This update requires the recognition of a right-of-use asset and a corresponding lease liability, discounted to the present value, for all leases that extend beyond 12 months. The Company adopted the new standard using a modified retrospective transition method, applying the transition provisions at the beginning of the period of adoption. The Company elected the package of practical expedients permitted under the transition guidance within the new standard and did not elect to use hindsight in determining the lease term. Upon adoption of the new standard, 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 recorded right-of-use assets of $17.2 million and lease liabilities of $17.8 million at adoption of the new standard associated with operating leases for office space in Bermuda, North Carolina, Virginia, Arizona, and Georgia. The new standard did not materially impact the Company's results of operations, earnings per share, or cash flows, and did not impact compliance under the covenants of our current credit agreements. At September 30, 2019 , right-of-use assets and lease liabilities were $16.2 million and $17.1 million , respectively. Operating lease costs were $1.3 million and $3.8 million in the three and nine months ended September 30, 2019 , respectively, compared to $1.3 million and $3.5 million in the respective prior year periods. The weighted-average discount rate and weighted average remaining lease term for operating leases was 4.3% and 5.5 years , respectively, as of September 30, 2019 . The table below summarizes maturities of the Company’s operating lease liabilities as of September 30, 2019 , which reconciles to total lease liabilities included in other liabilities on the Company’s condensed consolidated balance sheet: Years ending December 31, (in thousands) 2019 $ 959 2020 3,680 2021 3,491 2022 3,293 2023 3,099 Thereafter 4,706 Total lease payments 19,228 Less imputed interest (2,159 ) Total operating lease liabilities $ 17,069 Prospective Accounting Standards In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Current GAAP requires the recognition of credit losses when it is probable a loss has been incurred. The update will require 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 will also be 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. This ASU is effective for annual and interim reporting periods beginning after December 15, 2019. The Company plans to adopt the ASU on January 1, 2020 using the modified-retrospective approach, by which a cumulative-effect adjustment will be made to retained earnings as of the date of adoption. The Company is finalizing its implementation process for the adoption of this ASU and the evaluation of what effects the new standard will have on the Company’s financial statements. This ASU will have the greatest impact on our portfolio of bank loan participations and on our allowance for uncollectible reinsurance balances. In connection with the adoption of this ASU, we expect to elect the fair value option in accounting for bank loan participations effective January 1, 2020. We also expect to use the targeted transition relief offered by ASU 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief to also 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 will be measured at fair value, and changes in unrealized gains and losses in bank loan participations will be reported in our income statement as net realized and unrealized gains (losses) on investments. Upon adoption of this ASU, we anticipate that we will establish an allowance for uncollectible reinsurance balances, but because we purchase reinsurance from financially strong reinsurers or we have collateral securing the recoverables, we do not expect that the effect of adoption will be material to our financial position.

Accounting Policies (Tables)

Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Summary of Operating Leases Maturity	The table below summarizes maturities of the Company’s operating lease liabilities as of September 30, 2019 , which reconciles to total lease liabilities included in other liabilities on the Company’s condensed consolidated balance sheet: Years ending December 31, (in thousands) 2019 $ 959 2020 3,680 2021 3,491 2022 3,293 2023 3,099 Thereafter 4,706 Total lease payments 19,228 Less imputed interest (2,159 ) Total operating lease liabilities $ 17,069

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2019
Investments [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) September 30, 2019 Fixed maturity securities: State and municipal $ 145,016 $ 9,460 $ (89 ) $ 154,387 Residential mortgage-backed 245,315 2,849 (951 ) 247,213 Corporate 603,524 21,887 (231 ) 625,180 Commercial mortgage and asset-backed 230,417 5,221 (434 ) 235,204 U.S. Treasury securities and obligations guaranteed by the U.S. government 111,834 1,538 (40 ) 113,332 Redeemable preferred stock 2,025 — (18 ) 2,007 Total fixed maturity securities, available-for-sale $ 1,338,131 $ 40,955 $ (1,763 ) $ 1,377,323 December 31, 2018 Fixed maturity securities: State and municipal $ 147,160 $ 3,422 $ (1,287 ) $ 149,295 Residential mortgage-backed 208,869 577 (5,337 ) 204,109 Corporate 534,024 1,516 (10,772 ) 524,768 Commercial mortgage and asset-backed 199,528 310 (2,813 ) 197,025 U.S. Treasury securities and obligations guaranteed by the U.S. government 107,803 235 (845 ) 107,193 Redeemable preferred stock 2,025 — (213 ) 1,812 Total fixed maturity securities, available-for-sale $ 1,199,409 $ 6,060 $ (21,267 ) $ 1,184,202
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 September 30, 2019 are summarized, by contractual maturity, as follows: Cost or Fair (in thousands) One year or less $ 76,678 $ 77,005 After one year through five years 459,889 470,945 After five years through ten years 205,048 214,952 After ten years 118,759 129,997 Residential mortgage-backed 245,315 247,213 Commercial mortgage and asset-backed 230,417 235,204 Redeemable preferred stock 2,025 2,007 Total $ 1,338,131 $ 1,377,323
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) September 30, 2019 Fixed maturity securities: State and municipal $ 14,250 $ (87 ) $ 667 $ (2 ) $ 14,917 $ (89 ) Residential mortgage-backed 21,623 (34 ) 60,059 (917 ) 81,682 (951 ) Corporate 17,310 (149 ) 29,627 (82 ) 46,937 (231 ) Commercial mortgage and asset-backed 18,225 (70 ) 52,823 (364 ) 71,048 (434 ) U.S. Treasury securities and obligations guaranteed by the U.S. government 105 (1 ) 16,030 (39 ) 16,135 (40 ) Redeemable preferred stock 2,007 (18 ) — — 2,007 (18 ) Total fixed maturity securities, available-for-sale $ 73,520 $ (359 ) $ 159,206 $ (1,404 ) $ 232,726 $ (1,763 ) December 31, 2018 Fixed maturity securities: State and municipal $ 19,733 $ (284 ) $ 47,018 $ (1,003 ) $ 66,751 $ (1,287 ) Residential mortgage-backed 49,180 (743 ) 105,778 (4,594 ) 154,958 (5,337 ) Corporate 243,384 (5,089 ) 155,902 (5,683 ) 399,286 (10,772 ) Commercial mortgage and asset-backed 106,423 (1,229 ) 51,805 (1,584 ) 158,228 (2,813 ) U.S. Treasury securities and obligations guaranteed by the U.S. government 17,618 (51 ) 54,201 (794 ) 71,819 (845 ) Redeemable preferred stock 1,812 (213 ) — — 1,812 (213 ) Total fixed maturity securities, available-for-sale $ 438,150 $ (7,609 ) $ 414,704 $ (13,658 ) $ 852,854 $ (21,267 )
Schedule of summary of realized gains and losses	The Company’s net realized and unrealized gains and losses on investments are summarized as follows: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Fixed maturity securities: Gross realized gains $ 445 $ 12 $ 1,033 $ 394 Gross realized losses (9 ) (225 ) (494 ) (700 ) 436 (213 ) 539 (306 ) Bank loan participations: Gross realized gains 79 186 229 1,766 Gross realized losses (6,056 ) — (9,056 ) (1,106 ) (5,977 ) 186 (8,827 ) 660 Equity securities: Gross realized gains 11 — 11 — Gross realized losses (78 ) — (96 ) (62 ) Changes in fair values of equity securities 3,251 494 8,700 (695 ) 3,184 494 8,615 (757 ) Short-term investments and other: Gross realized gains 1 — 5 — Gross realized losses (1 ) — (1 ) (4 ) — — 4 (4 ) Total $ (2,357 ) $ 467 $ 331 $ (407 )
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 September 30, December 31, Three Months Ended Nine Months Ended 2019 2018 2019 2018 2019 2018 (in thousands) Renewable energy LLCs (a) $ 31,618 $ 29,795 $ 1,602 $ 329 $ 2,510 $ 2,070 Renewable energy notes receivable ( b) 8,750 8,750 328 328 984 954 Limited partnerships (c) 20,996 29,276 (631 ) 989 2,166 2,307 Bank holding companies (d) 4,500 4,500 85 85 257 257 Total other invested assets $ 65,864 $ 72,321 $ 1,384 $ 1,731 $ 5,917 $ 5,588 (a) The Company’s Corporate and Other segment owns equity interests ranging from 2.6% to 32.2% 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 one of our directors serves as an officer, and the Company’s Chairman and Chief Executive Officer ("CEO") 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 $687,000 and $2.8 million in the nine months ended September 30, 2019 and 2018 , respectively. (b) The Company's Corporate and Other segment has invested in notes receivable for renewable energy projects. At September 30, 2019 , the Company holds an $8.8 million note issued by an entity for which one of our directors serves as an officer . Interest on the note, which matures in 2021, is fixed at 15.0% . Interest income on the note was $328,000 and $984,000 for the three and nine months ended September 30, 2019 , respectively ( $328,000 and $954,000 for the three and nine months ended September 30, 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 f rom the partnerships is recognized under the equity method of accounting. The Company’s Corporate and Other segment held an investment in a limited partnership with a carrying value of $3.3 million at September 30, 2019 . The Company recognized investment income of $182,000 and $474,000 on the investment for the nine months ended September 30, 2019 and 2018 , respectively. The Company’s Excess and Surplus Lines segment holds investments in limited partnerships of $17.7 million at September 30, 2019 . Investment income of $2.0 million and $1.8 million was recognized on the investments for the nine months ended September 30, 2019 and 2018 , respectively. At September 30, 2019 , the Company’s Excess and Surplus Lines segment has outstanding commitments to invest another $625,000 in these limited partnerships. (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 Chairman and CEO 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 holder of the subordinated notes (the "Bank Holding Company"). Interest on the notes, which mature on August 12, 2023, is fixed at 7.6% per annum. Interest income on the notes was $257,000 in both the nine months ended September 30, 2019 and 2018 , respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2019
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: September 30, 2019 December 31, 2018 Life Gross Accumulated Gross Accumulated ($ in thousands) Intangible Assets 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 5,685 11,611 5,238 Identifiable intangible assets subject to amortization 11,611 5,685 11,611 5,238 $ 42,775 $ 5,685 $ 42,775 $ 5,238

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [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 condensed consolidated financial statements: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands, except share and per share amounts) Net (loss) income to shareholders $ (25,167 ) $ 19,581 $ 17,868 $ 52,198 Weighted average common shares outstanding: Basic 30,382,105 29,935,216 30,230,490 29,861,467 Common share equivalents — 444,929 428,899 428,716 Diluted 30,382,105 30,380,145 30,659,389 30,290,183 Earnings per share: Basic $ (0.83 ) $ 0.65 $ 0.59 $ 1.75 Common share equivalents — (0.01 ) (0.01 ) (0.03 ) Diluted $ (0.83 ) $ 0.64 $ 0.58 $ 1.72

Reserve for Losses and Loss A_2

Reserve for Losses and Loss Adjustment Expenses (Tables)	9 Months Ended
	Sep. 30, 2019
Liability for Claims and Claims Adjustment Expense [Abstract]
Schedule of reconciliation of beginning and ending reserve balances for losses and loss adjustment expenses	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: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Reserve for losses and loss adjustment expenses net of reinsurance recoverables at beginning of period $ 1,237,930 $ 1,092,818 $ 1,194,088 $ 989,825 Add: Incurred losses and loss adjustment expenses net of reinsurance: Current year 157,113 138,168 440,810 436,921 Prior years 56,971 12,219 60,254 11,833 Total incurred losses and loss and adjustment expenses 214,084 150,387 501,064 448,754 Deduct: Loss and loss adjustment expense payments net of reinsurance: Current year 21,021 25,149 46,275 57,903 Prior years 104,513 72,695 322,397 235,315 Total loss and loss adjustment expense payments 125,534 97,844 368,672 293,218 Reserve for losses and loss adjustment expenses net of reinsurance recoverables at end of period 1,326,480 1,145,361 1,326,480 1,145,361 Add: Reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period 614,827 424,400 614,827 424,400 Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period $ 1,941,307 $ 1,569,761 $ 1,941,307 $ 1,569,761

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2019
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of components of comprehensive income (loss)	The following table summarizes the components of other comprehensive income (loss): Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Unrealized gains (losses) arising during the period, before U.S. income taxes $ 10,531 $ (5,009 ) $ 54,937 $ (30,934 ) U.S. income taxes (690 ) 425 (4,045 ) 1,124 Unrealized gains (losses) arising during the period, net of U.S. income taxes 9,841 (4,584 ) 50,892 (29,810 ) Less reclassification adjustment: Net realized investment gains (losses) 436 (213 ) 539 (306 ) U.S. income taxes (52 ) 18 (96 ) (10 ) Reclassification adjustment for investment gains (losses) realized in net income 384 (195 ) 443 (316 ) Other comprehensive income (loss) $ 9,457 $ (4,389 ) $ 50,449 $ (29,494 )

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of summary of company's segment results	The following table summarizes the Company’s segment results: Excess and Surplus Lines Specialty Admitted Insurance Casualty Reinsurance Corporate and Other Total (in thousands) Three Months Ended September 30, 2019 Gross written premiums $ 241,045 $ 100,459 $ 46,724 $ — $ 388,228 Net earned premiums 164,759 14,242 34,373 — 213,374 Underwriting (loss) profit of insurance segments (29,351 ) 837 (4,288 ) — (32,802 ) Net investment income 3,467 976 11,717 1,718 17,878 Interest expense — — — 2,594 2,594 Segment revenues 170,734 16,493 42,403 1,844 231,474 Segment goodwill 181,831 — — — 181,831 Segment assets 1,186,094 773,677 1,631,569 69,576 3,660,916 Three Months Ended September 30, 2018 Gross written premiums $ 157,237 $ 98,607 $ 24,125 $ — $ 279,969 Net earned premiums 141,529 13,898 49,263 — 204,690 Underwriting profit of insurance segments 11,302 1,769 1,576 — 14,647 Net investment income 4,542 825 10,031 1,012 16,410 Interest expense — — — 2,991 2,991 Segment revenues 149,807 14,400 59,416 1,069 224,692 Segment goodwill 181,831 — — — 181,831 Segment assets 929,408 630,982 1,393,721 81,323 3,035,434 Excess and Specialty Casualty Corporate Total (in thousands) Nine Months Ended September 30, 2019 Gross written premiums $ 687,871 $ 292,884 $ 114,810 $ — $ 1,095,565 Net earned premiums 457,352 39,688 105,600 — 602,640 Underwriting (loss) profit of insurance segments (439 ) 3,758 (4,061 ) — (742 ) Net investment income 13,240 2,791 34,875 3,938 54,844 Interest expense — — — 8,086 8,086 Segment revenues 481,745 45,169 134,731 4,330 665,975 Segment goodwill 181,831 — — — 181,831 Segment assets 1,186,094 773,677 1,631,569 69,576 3,660,916 Nine Months Ended September 30, 2018 Gross written premiums $ 490,121 $ 283,108 $ 98,234 $ — $ 871,463 Net earned premiums 410,627 41,504 161,711 — 613,842 Underwriting profit of insurance segments 32,718 4,380 5,049 — 42,147 Net investment income 11,934 2,375 27,710 3,782 45,801 Interest expense — — — 8,459 8,459 Segment revenues 434,146 43,791 189,196 3,944 671,077 Segment goodwill 181,831 — — — 181,831 Segment assets 929,408 630,982 1,393,721 81,323 3,035,434
Schedule of underwriting profit of operating segments by individual segment and reconciliation to consolidated income before taxes	The following table reconciles the underwriting profit (loss) of the operating segments by individual segment to consolidated income before taxes: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Underwriting (loss) profit of the insurance segments: Excess and Surplus Lines $ (29,351 ) $ 11,302 $ (439 ) $ 32,718 Specialty Admitted Insurance 837 1,769 3,758 4,380 Casualty Reinsurance (4,288 ) 1,576 (4,061 ) 5,049 Total underwriting (loss) profit of insurance segments (32,802 ) 14,647 (742 ) 42,147 Other operating expenses of the Corporate and Other segment (7,302 ) (6,526 ) (22,641 ) (21,264 ) Underwriting (loss) profit (40,104 ) 8,121 (23,383 ) 20,883 Net investment income 17,878 16,410 54,844 45,801 Net realized and unrealized (losses) gains on investments (2,357 ) 467 331 (407 ) Amortization of intangible assets (149 ) (149 ) (447 ) (447 ) Other income and expenses (91 ) 258 (223 ) 366 Interest expense (2,594 ) (2,991 ) (8,086 ) (8,459 ) (Loss) income before taxes $ (27,417 ) $ 22,116 $ 23,036 $ 57,737

Other Operating Expenses and _2

Other Operating Expenses and Other Expenses (Tables)	9 Months Ended
	Sep. 30, 2019
Other Operating Expenses And Other Expenses [Abstract]
Schedule of other operating expenses	Other operating expenses consist of the following: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Amortization of policy acquisition costs $ 21,258 $ 27,511 $ 63,029 $ 86,381 Other underwriting expenses of the operating segments 13,132 15,143 46,617 48,069 Other operating expenses of the Corporate and Other segment 7,302 6,526 22,641 21,264 Total $ 41,692 $ 49,180 $ 132,287 $ 155,714

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
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 September 30, 2019 are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ — $ 154,387 $ — $ 154,387 Residential mortgage-backed — 247,213 — 247,213 Corporate — 625,180 — 625,180 Commercial mortgage and asset-backed — 235,204 — 235,204 U.S. Treasury securities and obligations guaranteed by the U.S. government 112,826 506 — 113,332 Redeemable preferred stock — 2,007 — 2,007 Total fixed maturity securities, available-for-sale $ 112,826 $ 1,264,497 $ — $ 1,377,323 Equity securities: Preferred stock — 69,552 — 69,552 Common stock 15,065 4,179 44 19,288 Total equity securities $ 15,065 $ 73,731 $ 44 $ 88,840 Short-term investments $ — $ 49,884 $ — $ 49,884 Assets measured at fair value on a recurring basis as of December 31, 2018 are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) Fixed maturity securities, available-for-sale: State and municipal $ — $ 149,295 $ — $ 149,295 Residential mortgage-backed — 204,109 — 204,109 Corporate — 524,768 — 524,768 Commercial mortgage and asset-backed — 192,797 4,228 197,025 U.S. Treasury securities and obligations guaranteed by the U.S. government 106,651 542 — 107,193 Redeemable preferred stock — 1,812 — 1,812 Total fixed maturity securities, available-for-sale $ 106,651 $ 1,073,323 $ 4,228 $ 1,184,202 Equity securities: Preferred stock — 60,740 — 60,740 Common stock 16,674 757 214 17,645 Total equity securities $ 16,674 $ 61,497 $ 214 $ 78,385 Short-term investments $ 1,250 $ 80,716 $ — $ 81,966
Reconciliation of securities measured at fair value on a recurring basis	A reconciliation of the beginning and ending balances of available-for-sale fixed maturity securities and equity securities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is shown below: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands) (in thousands) Beginning balance $ 3,099 $ 4,680 $ 4,442 $ 4,680 Transfers out of Level 3 (3,010 ) — (7,238 ) — Transfers in to Level 3 — — 3,010 — Purchases — — — — Sales — — — — Maturities, calls and paydowns — (316 ) — (316 ) Amortization of discount — — — — Total gains or losses (realized/unrealized): Included in earnings (45 ) — (170 ) — Included in other comprehensive income — — — — Ending balance $ 44 $ 4,364 $ 44 $ 4,364
Schedule of assets measured at fair value on a nonrecurring basis	Assets measured at fair value on a nonrecurring basis are summarized below: Fair Value Measurements Using Quoted Prices Significant Significant Total (in thousands) September 30, 2019 Bank loan participations held-for-investment $ — $ — $ 6,361 $ 6,361 December 31, 2018 Bank loan participations held-for-investment $ — $ — $ — $ —
Schedule of carrying value and fair value	The carrying values and fair values of financial instruments are summarized below: September 30, 2019 December 31, 2018 Carrying Fair Value Carrying Fair Value (in thousands) Assets Fixed maturity securities, available-for-sale $ 1,377,323 $ 1,377,323 $ 1,184,202 $ 1,184,202 Equity securities 88,840 88,840 78,385 78,385 Bank loan participations held-for-investment 249,907 242,628 260,972 250,697 Cash and cash equivalents 256,302 256,302 172,457 172,457 Short-term investments 49,884 49,884 81,966 81,966 Other invested assets – notes receivable 13,250 18,767 13,250 18,687 Liabilities Senior debt 98,300 101,256 118,300 118,317 Junior subordinated debt 104,055 125,008 104,055 117,057

Capital Stock and Equity Awar_2

Capital Stock and Equity Awards (Tables)	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
Schedule of dividends	The Company declared the following dividends during the first nine months of 2019 and 2018: Date of Declaration Dividend per Common Share Payable to Shareholders of Record on Payment Date Total Amount 2019 February 20, 2019 $ 0.30 March 11, 2019 March 29, 2019 $ 9,146,357 April 30, 2019 0.30 June 10, 2019 June 28, 2019 9,204,804 July 30, 2019 0.30 September 16, 2019 September 30, 2019 9,230,801 $ 0.90 $ 27,581,962 2018 February 22, 2018 $ 0.30 March 12, 2018 March 30, 2018 $ 9,049,476 May 1, 2018 0.30 June 11, 2018 June 29, 2018 9,066,023 August 1, 2018 0.30 September 10, 2018 September 28, 2018 9,080,519 $ 0.90 $ 27,196,018
Schedule of summary of option activity	The following table summarizes option activity: Nine Months Ended September 30, 2019 2018 Shares Weighted- Shares Weighted- Outstanding: Beginning of period 1,115,324 $ 29.02 1,479,236 $ 27.81 Granted — $ — — $ — Exercised (450,514 ) $ 26.68 (280,683 ) $ 21.03 Forfeited (12,058 ) $ 36.84 (42,215 ) $ 36.86 End of period 652,752 $ 30.50 1,156,338 $ 29.13 Exercisable, end of period 599,241 $ 29.44 841,763 $ 26.64
Schedule of summary of RSU activity	The following table summarizes RSU activity: Nine Months Ended September 30, 2019 2018 Shares Weighted- Shares Weighted- Unvested, beginning of period 300,142 $ 39.22 178,882 $ 37.93 Granted 197,078 $ 42.56 218,475 $ 39.75 Vested (111,212 ) $ 39.90 (63,191 ) $ 40.92 Forfeited (22,445 ) $ 41.32 (5,889 ) $ 40.81 Unvested, end of period 363,563 $ 40.69 328,277 $ 38.51
Schedule of share based 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: Three Months Ended Nine Months Ended 2019 2018 2019 2018 (in thousands) Share based compensation expense $ 1,779 $ 1,681 $ 5,263 $ 4,796 U.S. tax benefit on share based compensation expense 211 198 631 569

Accounting Policies - Narrative

Accounting Policies - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)company	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)company	Sep. 30, 2018USD ($)	Jan. 01, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 01, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investment in variable interest entities	$ 31,600		$ 31,600			$ 29,800
Effective U.S. federal income tax expense rate			22.40%	9.60%
Assets	3,660,916	$ 3,035,434	$ 3,660,916	$ 3,035,434		3,136,776
Liabilities	2,891,947		2,891,947			$ 2,427,535
Right-of-use assets	16,200		16,200
Total operating lease liabilities	17,069		17,069
Operating lease costs	$ 1,300	$ 1,300	$ 3,800	$ 3,500
Weighted average discount rate (as a percentage)	4.30%		4.30%
Weighted average remaining lease term (in years)	5 years 6 months		5 years 6 months
ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU							$ 0
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU					$ 8,280
Assets					(22,600)
Liabilities					(30,900)
Right-of-use assets					17,200
Total operating lease liabilities					17,800
Accumulated Other Comprehensive Income (Loss) | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU							711
Retained Earnings | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU							$ (711)
Retained Earnings | ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU					$ 8,280
UNITED STATES
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of insurance companies | company	5		5
BERMUDA
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of insurance companies | company	2		2

Accounting Policies - Summary o

Accounting Policies - Summary of Operating Lease Maturities (Details) $ in Thousands	Sep. 30, 2019USD ($)
Accounting Policies [Abstract]
2019	$ 959
2020	3,680
2021	3,491
2022	3,293
2023	3,099
Thereafter	4,706
Total lease payments	19,228
Less imputed interest	(2,159)
Total operating lease liabilities	$ 17,069

Investments - Narrative (Detail

Investments - Narrative (Details)	Sep. 30, 2019USD ($)issuer	Sep. 30, 2019USD ($)issuer	Mar. 31, 2019USD ($)security	Sep. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Sep. 30, 2019USD ($)loanissuer	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Gain (Loss) on Securities [Line Items]
Number of issuers | issuer	76	76				76
Total fair value	$ 232,726,000	$ 232,726,000				$ 232,726,000
Gross unrealized losses	1,763,000	1,763,000				1,763,000
Fixed maturity securities, available-for-sale	1,377,323,000	1,377,323,000				$ 1,377,323,000		$ 1,184,202,000
Number of impaired loans | loan						5
Carrying value of impaired loans	6,400,000	6,400,000				$ 6,400,000
Unpaid principal on impaired loans	12,300,000	12,300,000				12,300,000
Allowance for credit losses on impaired loans	5,900,000	5,900,000				5,900,000			$ 3,200,000
Net realized and unrealized (losses) gains on investments		(2,357,000)		$ 467,000		331,000	$ (407,000)
Average recorded investment in impaired bank loans						3,200,000	2,600,000
Investment income during period loans were impaired						23,000	125,000
Net realized gain (loss) on changes in fair value of impaired bank loans		(5,900,000)		$ 42,000		(7,700,000)	$ (851,000)
Carrying value of collateralized loan obligation held	3,400,000	3,400,000				3,400,000
Fixed maturity securities
Gain (Loss) on Securities [Line Items]
Total fair value								852,854,000
Gross unrealized losses								21,267,000
Fixed maturity securities, available-for-sale	$ 1,377,323,000	$ 1,377,323,000				$ 1,377,323,000		$ 1,184,202,000
Number of impaired fixed maturities | security			3
Impairment losses			$ 271,000
Bank Loan Portfolio
Gain (Loss) on Securities [Line Items]
Number of issuers | issuer	4	4				4
Loans from Issuer Experiencing Liquidity Concerns
Gain (Loss) on Securities [Line Items]
Number of issuers | issuer	1	1				1
Number of impaired loans | loan						2
Allowance for credit losses on impaired loans	$ 4,200,000	$ 4,200,000				$ 4,200,000
Puerto Rico loan
Gain (Loss) on Securities [Line Items]
Carrying value of impaired loans									0
Unpaid principal on impaired loans									$ 807,000
Net realized and unrealized (losses) gains on investments					$ 807,000
BBB- or better | Fixed maturity securities
Gain (Loss) on Securities [Line Items]
Percentage of available for sale securities	99.60%	99.60%				99.60%
Below BBB-
Gain (Loss) on Securities [Line Items]
Fixed maturity securities, available-for-sale	$ 5,300,000	$ 5,300,000				$ 5,300,000
Aggregate net unrealized gain (loss)	$ 79,000

Investments - Schedule of Avail

Investments - Schedule of Available-for-Sale Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	$ 1,338,131	$ 1,199,409
Fixed maturity securities, available-for-sale	1,377,323	1,184,202
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	1,338,131	1,199,409
Total investments available-for-sale, Gross Unrealized Gains	40,955	6,060
Total investments available-for-sale, Gross Unrealized Losses	(1,763)	(21,267)
Fixed maturity securities, available-for-sale	1,377,323	1,184,202
State and municipal
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	145,016	147,160
Total investments available-for-sale, Gross Unrealized Gains	9,460	3,422
Total investments available-for-sale, Gross Unrealized Losses	(89)	(1,287)
Fixed maturity securities, available-for-sale	154,387	149,295
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	245,315	208,869
Total investments available-for-sale, Gross Unrealized Gains	2,849	577
Total investments available-for-sale, Gross Unrealized Losses	(951)	(5,337)
Fixed maturity securities, available-for-sale	247,213	204,109
Corporate
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	603,524	534,024
Total investments available-for-sale, Gross Unrealized Gains	21,887	1,516
Total investments available-for-sale, Gross Unrealized Losses	(231)	(10,772)
Fixed maturity securities, available-for-sale	625,180	524,768
Commercial mortgage and asset-backed
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	230,417	199,528
Total investments available-for-sale, Gross Unrealized Gains	5,221	310
Total investments available-for-sale, Gross Unrealized Losses	(434)	(2,813)
Fixed maturity securities, available-for-sale	235,204	197,025
U.S. Treasury securities and obligations guaranteed by the U.S. government
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	111,834	107,803
Total investments available-for-sale, Gross Unrealized Gains	1,538	235
Total investments available-for-sale, Gross Unrealized Losses	(40)	(845)
Fixed maturity securities, available-for-sale	113,332	107,193
Redeemable preferred stock
Debt Securities, Available-for-sale [Line Items]
Total fixed maturity securities, Cost or Amortized Cost	2,025	2,025
Total investments available-for-sale, Gross Unrealized Gains	0	0
Total investments available-for-sale, Gross Unrealized Losses	(18)	(213)
Fixed maturity securities, available-for-sale	$ 2,007	$ 1,812

Investments - Schedule of Contr

Investments - Schedule of Contract Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Cost or Amortized Cost
One year or less	$ 76,678
After one year through five years	459,889
After five years through ten years	205,048
After ten years	118,759
Residential mortgage-backed	245,315
Commercial mortgage and asset-backed	230,417
Redeemable preferred stock	2,025
Total fixed maturity securities, Cost or Amortized Cost	1,338,131	$ 1,199,409
Fair Value
One year or less	77,005
After one year through five years	470,945
After five years through ten years	214,952
After ten years	129,997
Residential mortgage-backed	247,213
Commercial mortgage and asset-backed	235,204
Redeemable preferred stock	2,007
Total investments available-for-sale, Fair Value	$ 1,377,323	$ 1,184,202

Investments - Schedule of Gross

Investments - Schedule of Gross Unrealized Losses and Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, fair value	$ 232,726
Fixed maturity securities, gross unrealized losses	(1,763)
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, less than 12 months, fair value	73,520	$ 438,150
Fixed maturity securities, less than 12 months, gross unrealized losses	(359)	(7,609)
Fixed maturity securities, 12 months or more, fair value	159,206	414,704
Fixed maturity securities, 12 months or more, gross unrealized losses	(1,404)	(13,658)
Fixed maturity securities, fair value		852,854
Fixed maturity securities, gross unrealized losses		(21,267)
State and municipal
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, less than 12 months, fair value	14,250	19,733
Fixed maturity securities, less than 12 months, gross unrealized losses	(87)	(284)
Fixed maturity securities, 12 months or more, fair value	667	47,018
Fixed maturity securities, 12 months or more, gross unrealized losses	(2)	(1,003)
Fixed maturity securities, fair value	14,917	66,751
Fixed maturity securities, gross unrealized losses	(89)	(1,287)
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, less than 12 months, fair value	21,623	49,180
Fixed maturity securities, less than 12 months, gross unrealized losses	(34)	(743)
Fixed maturity securities, 12 months or more, fair value	60,059	105,778
Fixed maturity securities, 12 months or more, gross unrealized losses	(917)	(4,594)
Fixed maturity securities, fair value	81,682	154,958
Fixed maturity securities, gross unrealized losses	(951)	(5,337)
Corporate
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, less than 12 months, fair value	17,310	243,384
Fixed maturity securities, less than 12 months, gross unrealized losses	(149)	(5,089)
Fixed maturity securities, 12 months or more, fair value	29,627	155,902
Fixed maturity securities, 12 months or more, gross unrealized losses	(82)	(5,683)
Fixed maturity securities, fair value	46,937	399,286
Fixed maturity securities, gross unrealized losses	(231)	(10,772)
Commercial mortgage and asset-backed
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, less than 12 months, fair value	18,225	106,423
Fixed maturity securities, less than 12 months, gross unrealized losses	(70)	(1,229)
Fixed maturity securities, 12 months or more, fair value	52,823	51,805
Fixed maturity securities, 12 months or more, gross unrealized losses	(364)	(1,584)
Fixed maturity securities, fair value	71,048	158,228
Fixed maturity securities, gross unrealized losses	(434)	(2,813)
U.S. Treasury securities and obligations guaranteed by the U.S. government
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, less than 12 months, fair value	105	17,618
Fixed maturity securities, less than 12 months, gross unrealized losses	(1)	(51)
Fixed maturity securities, 12 months or more, fair value	16,030	54,201
Fixed maturity securities, 12 months or more, gross unrealized losses	(39)	(794)
Fixed maturity securities, fair value	16,135	71,819
Fixed maturity securities, gross unrealized losses	(40)	(845)
Redeemable preferred stock
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, less than 12 months, fair value	2,007	1,812
Fixed maturity securities, less than 12 months, gross unrealized losses	(18)	(213)
Fixed maturity securities, 12 months or more, fair value	0	0
Fixed maturity securities, 12 months or more, gross unrealized losses	0	0
Fixed maturity securities, fair value	2,007	1,812
Fixed maturity securities, gross unrealized losses	$ (18)	$ (213)

Investments - Summary of Realiz

Investments - Summary of Realized Gains and Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Investments [Abstract]
Fixed maturity securities, gross realized gains	$ 445	$ 12	$ 1,033	$ 394
Fixed maturity securities, gross realized losses	(9)	(225)	(494)	(700)
Fixed maturity securities	436	(213)	539	(306)
Bank loan participations, gross realized gains	79	186	229	1,766
Bank loan participations, gross realized losses	(6,056)	0	(9,056)	(1,106)
Bank loan participations	(5,977)	186	(8,827)	660
Equity securities, gross realized gain	11	0	11	0
Equity securities, gross realized losses	(78)	0	(96)	(62)
Equity securities, changes in fair values of equity securities	3,251	494	8,700	(695)
Equity securities	3,184	494	8,615	(757)
Short-term investments and other, gross realized gains	1	0	5	0
Short-term investments and other, gross realized losses	(1)	0	(1)	(4)
Short-term investments and other	0	0	4	(4)
Total	$ (2,357)	$ 467	$ 331	$ (407)

Investments - Summary of Privat

Investments - Summary of Private Debt and Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Net Investment Income [Line Items]
Total other invested assets	$ 65,864		$ 65,864		$ 72,321
Investment income	1,384	$ 1,731	5,917	$ 5,588
Renewable energy LLCs
Net Investment Income [Line Items]
Total other invested assets	31,618		31,618		29,795
Investment income	1,602	329	2,510	2,070
Renewable energy notes receivable
Net Investment Income [Line Items]
Total other invested assets	8,750		8,750		8,750
Investment income	$ 328	328	$ 984	954
Rate of interest	15.00%		15.00%
Limited partnerships
Net Investment Income [Line Items]
Total other invested assets	$ 20,996		$ 20,996		29,276
Investment income	(631)	989	2,166	2,307
Bank holding companies
Net Investment Income [Line Items]
Total other invested assets	4,500		4,500		$ 4,500
Investment income	$ 85	$ 85	257	257
Interest income			$ 257	257
Bank Holding Company
Net Investment Income [Line Items]
Rate of interest	7.60%		7.60%
Corporate and Other | Limited partnerships
Net Investment Income [Line Items]
Carrying values of limited partnerships held	$ 3,300		$ 3,300
Investment income (loss)			182	474
Corporate and Other | Investment in LLC
Net Investment Income [Line Items]
Cash distributions from LLCs			687	2,800
Corporate and Other | Bank Holding Company
Net Investment Income [Line Items]
Investment in private subordinated notes	4,500		4,500
Excess and Surplus Lines | Limited partnerships
Net Investment Income [Line Items]
Carrying values of limited partnerships held	17,700		17,700
Investment income (loss)			2,000	$ 1,800
Commitment to investment in limited partnership	$ 625		$ 625
Minimum | Corporate and Other | Investment in LLC
Net Investment Income [Line Items]
Ownership percentage	2.60%		2.60%
Maximum | Corporate and Other | Investment in LLC
Net Investment Income [Line Items]
Ownership percentage	32.20%		32.20%

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 11, 2007
Business Acquisition [Line Items]
Goodwill	$ 181,831	$ 181,831	$ 181,831
James River Group, Inc.
Business Acquisition [Line Items]
Percentage of outstanding shares				100.00%

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
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	5,685	5,238
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	$ 5,685	5,238
Life	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

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2018
Stock options and restricted share units ("RSU's")
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of securities excluded from the calculations of diluted earnings per share	431,137	173,758	182,870

Earnings Per Share - Basic and

Earnings Per Share - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net (loss) income to shareholders	$ (25,167)	$ 19,581	$ 17,868	$ 52,198
Weighted average common shares outstanding:
Basic (in shares)	30,382,105	29,935,216	30,230,490	29,861,467
Common share equivalents (in shares)	0	444,929	428,899	428,716
Diluted (in shares)	30,382,105	30,380,145	30,659,389	30,290,183
Earnings per share:
Basic (in dollars per share)	$ (0.83)	$ 0.65	$ 0.59	$ 1.75
Common share equivalents (in dollars per share)	0	(0.01)	(0.01)	(0.03)
Diluted (in dollars per share)	$ (0.83)	$ 0.64	$ 0.58	$ 1.72

Reserve for Losses and Loss A_3

Reserve for Losses and Loss Adjustment Expenses - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses	$ (56,971,000)	$ (12,219,000)	$ (60,254,000)	$ (11,833,000)
Excess and Surplus Lines
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses	(50,000,000)	10,400,000	(51,200,000)	(9,200,000)
Specialty Admitted Insurance
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses	1,000,000	833,000	4,300,000	2,300,000
Casualty Reinsurance
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses	$ (7,900,000)	(2,700,000)	$ (13,300,000)	(4,900,000)
Accident year 2017 | Excess and Surplus Lines
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses		$ 3,000,000		$ 4,900,000

Reserve for Losses and Loss A_4

Reserve for Losses and Loss Adjustment Expenses - Reconciliation of Losses and Loss Adjustment Balances (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 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	$ 1,237,930	$ 1,092,818	$ 1,194,088	$ 989,825
Add: Incurred losses and loss adjustment expenses net of reinsurance:
Current year	157,113	138,168	440,810	436,921
Prior years	56,971	12,219	60,254	11,833
Total incurred losses and loss and adjustment expenses	214,084	150,387	501,064	448,754
Deduct: Loss and loss adjustment expense payments net of reinsurance:
Current year	21,021	25,149	46,275	57,903
Prior years	104,513	72,695	322,397	235,315
Total loss and loss adjustment expense payments	125,534	97,844	368,672	293,218
Reserve for losses and loss adjustment expenses net of reinsurance recoverables at end of period	$ 1,237,930	$ 1,092,818	$ 1,194,088	$ 989,825	$ 1,326,480	$ 1,194,088	$ 1,145,361
Add: Reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period					614,827	467,371	424,400
Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period					$ 1,941,307	$ 1,661,459	$ 1,569,761

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) - Summary of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gains (losses) arising during the period, before U.S. income taxes	$ 10,531	$ (5,009)	$ 54,937	$ (30,934)
U.S. income taxes	(690)	425	(4,045)	1,124
Unrealized gains (losses) arising during the period, net of U.S. income taxes	9,841	(4,584)	50,892	(29,810)
Less reclassification adjustment:
Net realized investment gains (losses)	436	(213)	539	(306)
U.S. income taxes	(52)	18	(96)	(10)
Reclassification adjustment for investment gains (losses) realized in net income	384	(195)	443	(316)
Other comprehensive income (loss)	$ 9,457	$ (4,389)	$ 50,449	$ (29,494)

Other Comprehensive Income (L_4

Other Comprehensive Income (Loss) - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Fixed maturity securities	$ 436	$ (213)	$ 539	$ (306)
Bank loan participations	(5,977)	186	(8,827)	660
Equity securities, changes in fair values of equity securities	$ 3,251	$ 494	$ 8,700	$ (695)

Contingent Liabilities - Narrat

Contingent Liabilities - Narrative (Details) $ in Millions	Oct. 09, 2019USD ($)	Sep. 30, 2019USD ($)credit_facility
Contingent Liabilities [Line Items]
Number of credit facilities | credit_facility		3
JRG Reinsurance Company, Ltd. | Letter of credit 75 Million
Contingent Liabilities [Line Items]
Letters of credit facility, amount		$ 75
Amount of letters of credit issued		48.2
Assets deposited for securing letters of credit		60.9
JRG Reinsurance Company, Ltd. | Letter of credit 102.5 Million
Contingent Liabilities [Line Items]
Letters of credit facility, amount		102.5
Amount of letters of credit issued		64.1
Assets deposited for securing letters of credit		83.3
JRG Reinsurance Company, Ltd. | Letter of credit 100 Million
Contingent Liabilities [Line Items]
Letters of credit facility, amount		100
Amount of letters of credit issued		5.3
Assets deposited for securing letters of credit		10.9
James River Insurance Co
Contingent Liabilities [Line Items]
Collateral trust arrangement amount		1,168.9
Third-party Reinsureds | JRG Reinsurance Company, Ltd.
Contingent Liabilities [Line Items]
Collateral trust arrangement amount		$ 299.1
Subsequent Event | James River Insurance Co
Contingent Liabilities [Line Items]
Assets withdrawn from collateral trust arrangement	$ 1,170.7

Segment Information - Narrative

Segment Information - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)segment	Sep. 30, 2018USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			4
Fee income in Excess and Surplus Lines segment | $	$ 2.2	$ 3	$ 7.1	$ 11.5

Segment Information - Summary o

Segment Information - Summary of Segment Results (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Gross written premiums	$ 388,228	$ 279,969	$ 1,095,565	$ 871,463
Net earned premiums	213,374	204,690	602,640	613,842
Underwriting profit of insurance segments	(32,802)	14,647	(742)	42,147
Net investment income	17,878	16,410	54,844	45,801
Interest expense	2,594	2,991	8,086	8,459
Segment revenues	231,474	224,692	665,975	671,077
Segment goodwill	181,831	181,831	181,831	181,831	$ 181,831
Segment assets	3,660,916	3,035,434	3,660,916	3,035,434	$ 3,136,776
Excess and Surplus Lines
Segment Reporting Information [Line Items]
Gross written premiums	241,045	157,237	687,871	490,121
Net earned premiums	164,759	141,529	457,352	410,627
Underwriting profit of insurance segments	(29,351)	11,302	(439)	32,718
Net investment income	3,467	4,542	13,240	11,934
Interest expense	0	0	0	0
Segment revenues	170,734	149,807	481,745	434,146
Segment goodwill	181,831	181,831	181,831	181,831
Segment assets	1,186,094	929,408	1,186,094	929,408
Specialty Admitted Insurance
Segment Reporting Information [Line Items]
Gross written premiums	100,459	98,607	292,884	283,108
Net earned premiums	14,242	13,898	39,688	41,504
Underwriting profit of insurance segments	837	1,769	3,758	4,380
Net investment income	976	825	2,791	2,375
Interest expense	0	0	0	0
Segment revenues	16,493	14,400	45,169	43,791
Segment goodwill	0	0	0	0
Segment assets	773,677	630,982	773,677	630,982
Casualty Reinsurance
Segment Reporting Information [Line Items]
Gross written premiums	46,724	24,125	114,810	98,234
Net earned premiums	34,373	49,263	105,600	161,711
Underwriting profit of insurance segments	(4,288)	1,576	(4,061)	5,049
Net investment income	11,717	10,031	34,875	27,710
Interest expense	0	0	0	0
Segment revenues	42,403	59,416	134,731	189,196
Segment goodwill	0	0	0	0
Segment assets	1,631,569	1,393,721	1,631,569	1,393,721
Corporate and Other
Segment Reporting Information [Line Items]
Gross written premiums	0	0	0	0
Net earned premiums	0	0	0	0
Underwriting profit of insurance segments	0	0	0	0
Net investment income	1,718	1,012	3,938	3,782
Interest expense	2,594	2,991	8,086	8,459
Segment revenues	1,844	1,069	4,330	3,944
Segment goodwill	0	0	0	0
Segment assets	$ 69,576	$ 81,323	$ 69,576	$ 81,323

Segment Information - Reconcili

Segment Information - Reconciliation of Operating Segments by Individual Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Total underwriting (loss) profit of insurance segments	$ (32,802)	$ 14,647	$ (742)	$ 42,147
Other operating expenses of the Corporate and Other segment	(7,302)	(6,526)	(22,641)	(21,264)
Underwriting (loss) profit	(40,104)	8,121	(23,383)	20,883
Net investment income	17,878	16,410	54,844	45,801
Net realized and unrealized (losses) gains on investments	(2,357)	467	331	(407)
Amortization of intangible assets	(149)	(149)	(447)	(447)
Other income and expenses	(91)	258	(223)	366
Interest expense	(2,594)	(2,991)	(8,086)	(8,459)
(Loss) income before taxes	(27,417)	22,116	23,036	57,737
Excess and Surplus Lines
Segment Reporting Information [Line Items]
Total underwriting (loss) profit of insurance segments	(29,351)	11,302	(439)	32,718
Net investment income	3,467	4,542	13,240	11,934
Interest expense	0	0	0	0
Specialty Admitted Insurance
Segment Reporting Information [Line Items]
Total underwriting (loss) profit of insurance segments	837	1,769	3,758	4,380
Net investment income	976	825	2,791	2,375
Interest expense	0	0	0	0
Casualty Reinsurance
Segment Reporting Information [Line Items]
Total underwriting (loss) profit of insurance segments	(4,288)	1,576	(4,061)	5,049
Net investment income	11,717	10,031	34,875	27,710
Interest expense	$ 0	$ 0	$ 0	$ 0

Other Operating Expenses and _3

Other Operating Expenses and Other Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Operating Expenses And Other Expenses [Abstract]
Amortization of policy acquisition costs	$ 21,258	$ 27,511	$ 63,029	$ 86,381
Other underwriting expenses of the operating segments	13,132	15,143	46,617	48,069
Other operating expenses of the Corporate and Other segment	7,302	6,526	22,641	21,264
Total	41,692	49,180	132,287	155,714
Other expenses	$ 372	$ (131)	$ 1,055	$ (34)

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total fixed maturity securities, available-for-sale		$ 1,377,323		$ 1,184,202
Principal payment received		85,921	$ 113,980
Equity securities		88,840		78,385
Nonrecurring basis
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired bank loan participations held for investment		6,361		0
Nonrecurring basis | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired bank loan participations held for investment		6,361		0
Common stock | Recurring basis
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities		19,288		17,645
Common stock | Recurring basis | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities		$ 44		214
Market approach | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total fixed maturity securities, available-for-sale				$ 4,200
Principal payment received	$ 456

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	$ 1,377,323	$ 1,184,202
Equity securities:
Total equity securities	88,840	78,385
Short-term investments	49,884	81,966
Fixed maturity securities
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	1,377,323	1,184,202
State and municipal
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	154,387	149,295
Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	247,213	204,109
Corporate
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	625,180	524,768
Commercial mortgage and asset-backed
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	235,204	197,025
U.S. Treasury securities and obligations guaranteed by the U.S. government
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	113,332	107,193
Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	2,007	1,812
Recurring basis
Equity securities:
Short-term investments	49,884	81,966
Recurring basis | Fixed maturity securities
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	1,377,323	1,184,202
Recurring basis | State and municipal
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	154,387	149,295
Recurring basis | Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	247,213	204,109
Recurring basis | Corporate
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	625,180	524,768
Recurring basis | Commercial mortgage and asset-backed
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	235,204	197,025
Recurring basis | U.S. Treasury securities and obligations guaranteed by the U.S. government
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	113,332	107,193
Recurring basis | Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	2,007	1,812
Recurring basis | Equity securities
Equity securities:
Total equity securities	88,840	78,385
Recurring basis | Preferred stock
Equity securities:
Total equity securities	69,552	60,740
Recurring basis | Common stock
Equity securities:
Total equity securities	19,288	17,645
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1
Equity securities:
Short-term investments	0	1,250
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Fixed maturity securities
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	112,826	106,651
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | State and municipal
Fixed maturity securities, available-for-sale:
Total 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:
Total 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:
Total 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:
Total 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:
Total fixed maturity securities, available-for-sale	112,826	106,651
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Equity securities
Equity securities:
Total equity securities	15,065	16,674
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Preferred stock
Equity securities:
Total equity securities	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets Level 1 | Common stock
Equity securities:
Total equity securities	15,065	16,674
Recurring basis | Significant Other Observable Inputs Level 2
Equity securities:
Short-term investments	49,884	80,716
Recurring basis | Significant Other Observable Inputs Level 2 | Fixed maturity securities
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	1,264,497	1,073,323
Recurring basis | Significant Other Observable Inputs Level 2 | State and municipal
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	154,387	149,295
Recurring basis | Significant Other Observable Inputs Level 2 | Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	247,213	204,109
Recurring basis | Significant Other Observable Inputs Level 2 | Corporate
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	625,180	524,768
Recurring basis | Significant Other Observable Inputs Level 2 | Commercial mortgage and asset-backed
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	235,204	192,797
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:
Total fixed maturity securities, available-for-sale	506	542
Recurring basis | Significant Other Observable Inputs Level 2 | Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	2,007	1,812
Recurring basis | Significant Other Observable Inputs Level 2 | Equity securities
Equity securities:
Total equity securities	73,731	61,497
Recurring basis | Significant Other Observable Inputs Level 2 | Preferred stock
Equity securities:
Total equity securities	69,552	60,740
Recurring basis | Significant Other Observable Inputs Level 2 | Common stock
Equity securities:
Total equity securities	4,179	757
Recurring basis | Significant Unobservable Inputs Level 3
Equity securities:
Short-term investments	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Fixed maturity securities
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	0	4,228
Recurring basis | Significant Unobservable Inputs Level 3 | State and municipal
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Residential mortgage-backed
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Corporate
Fixed maturity securities, available-for-sale:
Total 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:
Total fixed maturity securities, available-for-sale	0	4,228
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:
Total fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Redeemable preferred stock
Fixed maturity securities, available-for-sale:
Total fixed maturity securities, available-for-sale	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Equity securities
Equity securities:
Total equity securities	44	214
Recurring basis | Significant Unobservable Inputs Level 3 | Preferred stock
Equity securities:
Total equity securities	0	0
Recurring basis | Significant Unobservable Inputs Level 3 | Common stock
Equity securities:
Total equity securities	$ 44	$ 214

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Securities Measured at Fair Value (Details) - Fair Value, Recurring - Available-for-sale fixed maturity securities and equity securities - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 3,099	$ 4,680	$ 4,442	$ 4,680
Transfers out of Level 3	(3,010)	0	(7,238)	0
Transfers in to Level 3	0	0	3,010	0
Purchases	0	0	0	0
Sales	0	0	0	0
Maturities, calls and paydowns	0	(316)	0	(316)
Amortization of discount	0	0	0	0
Total gains or losses (realized/unrealized)-Included in earnings	(45)	0	(170)	0
Total gains or losses (realized/unrealized)-Included in other comprehensive income	0	0	0	0
Ending balance	$ 44	$ 4,364	$ 44	$ 4,364

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Assets Fair Value on a Nonrecurring Basis (Details) - Nonrecurring basis - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loan participations held-for-investment	$ 6,361	$ 0
Quoted Prices in Active Markets for Identical Assets Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loan participations held-for-investment	0	0
Significant Other Observable Inputs Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loan participations held-for-investment	0	0
Significant Unobservable Inputs Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loan participations held-for-investment	$ 6,361	$ 0

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Fixed maturity securities, available-for-sale	$ 1,377,323	$ 1,184,202
Equity securities	88,840	78,385
Bank loan participations held-for-investment	249,907	260,972
Cash and cash equivalents	256,302	172,457
Short-term investments	49,884	81,966
Liabilities
Senior debt	98,300	118,300
Junior subordinated debt	104,055	104,055
Carrying Value
Assets
Fixed maturity securities, available-for-sale	1,377,323	1,184,202
Equity securities	88,840	78,385
Bank loan participations held-for-investment	249,907	260,972
Cash and cash equivalents	256,302	172,457
Short-term investments	49,884	81,966
Other invested assets – notes receivable	13,250	13,250
Liabilities
Senior debt	98,300	118,300
Junior subordinated debt	104,055	104,055
Fair Value
Assets
Fixed maturity securities, available-for-sale	1,377,323	1,184,202
Equity securities	88,840	78,385
Bank loan participations held-for-investment	242,628	250,697
Cash and cash equivalents	256,302	172,457
Short-term investments	49,884	81,966
Other invested assets – notes receivable	18,767	18,687
Liabilities
Senior debt	101,256	118,317
Junior subordinated debt	$ 125,008	$ 117,057

Capital Stock and Equity Awar_3

Capital Stock and Equity Awards - Commons Shares (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares outstanding (in shares)	30,401,270			29,988,460
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock unit dividend equivalents	$ 327	$ 297
Dividends payable	$ 651			$ 557
Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common shares issued during period (in shares)	412,810
Common stock, shares outstanding (in shares)	30,401,270	29,950,120	30,330,675	29,988,460	29,917,821	29,696,682
Common stock | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common shares issued during period (in shares)	336,533
Common stock | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common shares issued during period (in shares)	76,277

Capital Stock and Equity Awar_4

Capital Stock and Equity Awards - Schedule of Dividends (Details) - USD ($)	Sep. 30, 2019	Jul. 30, 2019	Jun. 28, 2019	Apr. 30, 2019	Mar. 29, 2019	Feb. 20, 2019	Sep. 28, 2018	Aug. 01, 2018	Jun. 29, 2018	May 01, 2018	Mar. 30, 2018	Feb. 22, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 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	$ 0.90	$ 0.90
Total Amount	$ 9,230,801		$ 9,204,804		$ 9,146,357		$ 9,080,519		$ 9,066,023		$ 9,049,476				$ 27,581,962	$ 27,196,018

Capital Stock and Equity Awar_5

Capital Stock and Equity Awards - Equity Incentive Plans (Details) - shares	Apr. 30, 2019	Sep. 30, 2019
2014 LTIP | Non-qualified stock options
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		1,575,359
2014 Director 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		108,594
Increase in number of shares authorized for issuance (in shares)	100,000

Capital Stock and Equity Awar_6

Capital Stock and Equity Awards - Summary of Option Activity (Details) - $ / shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Weighted- Average Exercise Price
Weighted-average remaining contractual life of options outstanding	3 years 2 months 12 days
Weighted-average remaining contractual life of options exercisable	3 years 1 month 6 days
Options
Shares
Beginning of period (in shares)	1,115,324	1,479,236
Granted (in shares)	0	0
Exercised (in shares)	(450,514)	(280,683)
Forfeited (in shares)	(12,058)	(42,215)
End of period (in shares)	652,752	1,156,338
Exercisable, end of period (in shares)	599,241	841,763
Weighted- Average Exercise Price
Beginning of period (in dollars per share)	$ 29.02	$ 27.81
Granted (in dollars per share)	0	0
Exercised (in dollars per share)	26.68	21.03
Forfeited (in dollars per share)	36.84	36.86
End of period (in dollars per share)	30.50	29.13
Exercisable, end of period (in dollars per share)	$ 29.44	$ 26.64
Contractual life (in years)	7 years
Minimum | Options
Weighted- Average Exercise Price
Vesting period (in years)	3 years
Maximum | Options
Weighted- Average Exercise Price
Vesting period (in years)	4 years

Capital Stock and Equity Awar_7

Capital Stock and Equity Awards - Summary of RSU Activity (Details) - RSUs - $ / shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Shares
Unvested, beginning of period (in shares)	300,142	178,882
Granted (in shares)	197,078	218,475
Vested (in shares)	(111,212)	(63,191)
Forfeited (in shares)	(22,445)	(5,889)
Unvested, end of period (in shares)	363,563	328,277
Weighted- Average Grant Date Fair Value
Unvested, beginning of period (in dollars per share)	$ 39.22	$ 37.93
Granted (in dollars per share)	42.56	39.75
Vested (in dollars per share)	39.90	40.92
Forfeited (in dollars per share)	41.32	40.81
Unvested, end of period (in dollars per share)	$ 40.69	$ 38.51
Vesting period (in years)	3 years
Non-employee directors
Weighted- Average Grant Date Fair Value
Vesting period (in years)	1 year
Minimum
Weighted- Average Grant Date Fair Value
Vesting period (in years)	1 year
Maximum
Weighted- Average Grant Date Fair Value
Vesting period (in years)	5 years

Capital Stock and Equity Awar_8

Capital Stock and Equity Awards - Summary of Share Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stockholders' Equity Note [Abstract]
Share based compensation expense	$ 1,779	$ 1,681	$ 5,263	$ 4,796
U.S. tax benefit on share based compensation expense	$ 211	$ 198	$ 631	$ 569

Capital Stock and Equity Awar_9

Capital Stock and Equity Awards - Compensation Expense (Details) $ in Millions	3 Months Ended
	Sep. 30, 2019USD ($)
Equity [Abstract]
Unrecognized share based compensation expense	$ 10.5
Weighted-average period of unrecognized share based compensation expense	1 year 9 months 18 days

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2019	Dec. 16, 2019	Nov. 05, 2019	Oct. 09, 2019
Subsequent Event [Line Items]
Cash dividend declared (in dollars per share)			$ 0.30
Dividends payable, date to be paid	Dec. 31, 2019
Dividend payable, record date		Dec. 16, 2019
James River Insurance Co
Subsequent Event [Line Items]
Assets withdrawn from collateral trust arrangement				$ 1,170.7
Affiliated Entity | James River Insurance Co
Subsequent Event [Line Items]
Assets withdrawn from collateral trust arrangement				$ 1,170.7

Uncategorized Items - jrvr09302

Label	Element	Value
Accounting Standards Update 2016-01 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 0
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	4,682,000
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (4,682,000)