Selective Insurance (SIGI) 10-K 15 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 07, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Registrant Name	SELECTIVE INSURANCE GROUP INC
Entity Central Index Key	230,557
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 3,169,745,480
Entity Common Stock, Shares Outstanding		58,966,940
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Fixed income securities, held-to-maturity – at carrying value (fair value: $38,317 – 2018; $44,100 – 2017)	$ 37,110	$ 42,129
Fixed income securities, available-for-sale – at fair value (amortized cost: $5,270,798 – 2018; $5,076,716 – 2017)	5,273,100	5,162,522
Equity securities, available for sale – at fair value (cost: $143,811 – 2017)		182,705
Equity securities - at fair value (cost: $138,114 - 2018)	147,639
Short-term investments (at cost which approximates fair value)	323,864	165,555
Other investments	178,938	132,268
Total investments (Notes 5 and 7)	5,960,651	5,685,179
Cash	505	534
Restricted cash	16,414	44,176
Interest and dividends due or accrued	41,620	40,897
Premiums receivable, net of allowance for uncollectible accounts of: $9,400 – 2018; $10,000 – 2017	770,518	747,029
Reinsurance recoverable, net of allowance for uncollectible accounts of: $4,500 – 2018; $4,600 – 2017 (Note 8)	549,172	594,832
Prepaid reinsurance premiums (Note 8)	157,723	153,493
Current federal income tax (Note 13)	0	3,243
Deferred federal income tax (Note 13)	53,540	31,990
Property and equipment – at cost, net of accumulated depreciation and amortization of: $211,657 – 2018; $213,227 – 2017	65,248	63,959
Deferred policy acquisition costs (Note 2)	252,612	235,055
Goodwill (Note 11)	7,849	7,849
Other assets	76,877	78,195
Total assets	7,952,729	7,686,431
LIABILITIES AND STOCKHOLDERS’ EQUITY
Reserve for loss and loss expense (Note 9)	3,893,868	3,771,240
Unearned premiums	1,431,932	1,349,644
Long-term debt (Note 10)	439,540	439,116
Current federal income tax (Note 13)	1,302	0
Accrued salaries and benefits	116,706	131,850
Other liabilities	277,579	281,624
Total liabilities	6,160,927	5,973,474
Stockholders’ Equity:
Preferred stock of $0 par value per share: Authorized shares: 5,000,000; no shares issued or outstanding	0	0
Common stock of $2 par value per share Authorized shares: 360,000,000 Issued: 102,848,394 - 2018; 102,284,564 - 2017	205,697	204,569
Additional paid-in capital	390,315	367,717
Retained earnings	1,858,414	1,698,613
Accumulated other comprehensive (loss) income (Note 6)	(77,956)	20,170
Treasury stock – at cost (shares: 43,899,840 – 2018; 43,789,442 – 2017)	(584,668)	(578,112)
Total stockholders’ equity	1,791,802	1,712,957
Commitments and contingencies (Notes 17 and 18)
Total liabilities and stockholders’ equity	$ 7,952,729	$ 7,686,431

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed income securities, held-to-maturity, fair value	$ 38,317	$ 44,100
Fixed income securities, available-for-sale, amortized cost	5,270,798	5,076,716
Equity securities, cost		143,811
Equity Securities, FV-NI, Cost	138,114
Premiums receivable, allowance for uncollectible accounts	9,400	10,000
Reinsurance recoverable, allowance for uncollectible accounts	4,500	4,600
Property and equipment, accumulated depreciation and amortization	$ 211,657	$ 213,227
Preferred stock, par value per share	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 2	$ 2
Common stock, shares authorized	360,000,000	360,000,000
Common stock, shares issued	102,848,394	102,284,564
Treasury stock, shares	43,899,840	43,789,442

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Net premiums earned	$ 2,436,229	$ 2,291,027	$ 2,149,572
Net investment income earned	195,336	161,882	130,754
Net realized and unrealized (losses) gains:
Net realized investment (losses) gains on disposals	(18,975)	11,204	3,562
Other-than-temporary impairments	(6,579)	(4,809)	(8,509)
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	(36)	10
Net unrealized losses on equity securities	(29,369)	0	0
Total net realized and unrealized (losses) gains	(54,923)	6,359	(4,937)
Other income	9,438	10,716	8,881
Total revenues	2,586,080	2,469,984	2,284,270
Expenses:
Loss and loss expense incurred	1,498,134	1,345,074	1,234,797
Amortization of deferred policy acquisition costs	495,042	469,236	450,328
Other insurance expenses	331,318	333,097	321,395
Interest expense	24,419	24,354	22,771
Corporate expenses	25,446	36,255	35,024
Total expenses	2,374,359	2,208,016	2,064,315
Income before federal income tax	211,721	261,968	219,955
Federal income tax expense:
Current	35,012	62,184	48,581
Deferred	(2,230)	30,958	12,879
Total federal income tax expense	32,782	93,142	61,460
Net income	$ 178,939	$ 168,826	$ 158,495
Earnings per share:
Basic net income	$ 3.04	$ 2.89	$ 2.74
Diluted net income	$ 3	$ 2.84	$ 2.70

Consolidation Statements of Com

Consolidation Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income	$ 178,939	$ 168,826	$ 158,495
Unrealized holding (losses) gains arising during year	(97,284)	43,015	(5,977)
Non-credit portion of other-than-temporary impairments recognized in other comprehensive income	0	23	(6)
Amounts reclassified into net income: Held-to-maturity securities	87	(116)	(92)
Amounts reclassified into net income: Non-credit other-than-temporary impairment	0	68	138
Amounts reclassified into net income: Realized losses (gains) on available for sale securities	31,316	(4,537)	3,064
Total unrealized (losses) gains on investment securities	(65,881)	38,453	(2,873)
Net actuarial loss	(8,906)	(3,700)	(7,852)
Amounts reclassified into net income: Net actuarial loss	1,680	1,367	4,200
Total defined benefit pension and post-retirement plans	(7,226)	(2,333)	(3,652)
Other comprehensive (loss) income	(73,107)	36,120	(6,525)
Comprehensive income	$ 105,832	$ 204,946	$ 151,970

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Common Stock [Member]	Additional paid-in capital [Member]	Retained Earnings [Member]	Accumulated other comprehensive (loss) income [Member]	Treasury stock [Member]
Balance at beginning of year, as adjusted					$ 1,446,192	$ (9,425)
Beginning of year at Dec. 31, 2015			$ 201,723	$ 326,656	1,446,192	(9,425)	$ (567,105)
Dividend reinvestment plan (shares: 23,493 – 2018; 28,607 – 2017; 38,741 – 2016)			77	1,389
Stock purchase and compensation plans (shares: 540,337 – 2018; 635,521 – 2017; 720,323 – 2016)			1,441	19,250
Net income		$ 158,495			158,495
Dividends to stockholders ($0.74 per share – 2018; $0.66 per share – 2017; $0.61 per share – 2016)					(35,806)
Other comprehensive (loss) income		(6,525)				(6,525)
Acquisition of treasury stock (shares: 110,398 – 2018; 136,205 – 2017; 152,595 – 2016)							(4,992)
End of year at Dec. 31, 2016		1,531,370	203,241	347,295	1,568,881	(15,950)	(572,097)
Cumulative effect adjustment | Accounting Standards Update 2016-01 [Member]		0			0	0
Cumulative effect adjustment | Accounting Standards Update 2018-02 [Member]					0	0
Balance at beginning of year, as adjusted					1,568,881	(15,950)
Dividend reinvestment plan (shares: 23,493 – 2018; 28,607 – 2017; 38,741 – 2016)			57	1,395
Stock purchase and compensation plans (shares: 540,337 – 2018; 635,521 – 2017; 720,323 – 2016)			1,271	19,027
Net income		168,826			168,826
Dividends to stockholders ($0.74 per share – 2018; $0.66 per share – 2017; $0.61 per share – 2016)					(39,094)
Other comprehensive (loss) income		36,120				36,120
Acquisition of treasury stock (shares: 110,398 – 2018; 136,205 – 2017; 152,595 – 2016)							(6,015)
End of year at Dec. 31, 2017		1,712,957	204,569	367,717	1,698,613	20,170	(578,112)
Cumulative effect adjustment	[1]					(25,019)
Cumulative effect adjustment | Accounting Standards Update 2016-01 [Member]		0			0	0
Cumulative effect adjustment | Accounting Standards Update 2018-02 [Member]					0	0
Balance at beginning of year, as adjusted					1,723,632	(4,849)
Dividend reinvestment plan (shares: 23,493 – 2018; 28,607 – 2017; 38,741 – 2016)			47	1,379
Stock purchase and compensation plans (shares: 540,337 – 2018; 635,521 – 2017; 720,323 – 2016)			1,081	21,219
Net income		178,939			178,939
Dividends to stockholders ($0.74 per share – 2018; $0.66 per share – 2017; $0.61 per share – 2016)					(44,157)
Other comprehensive (loss) income		(73,107)				(73,107)
Acquisition of treasury stock (shares: 110,398 – 2018; 136,205 – 2017; 152,595 – 2016)							(6,556)
End of year at Dec. 31, 2018		1,791,802	$ 205,697	$ 390,315	1,858,414	(77,956)	$ (584,668)
Cumulative effect adjustment | Accounting Standards Update 2016-01 [Member]		$ (30,726)			30,726	(30,726)
Cumulative effect adjustment | Accounting Standards Update 2018-02 [Member]					$ (5,707)	$ 5,707
[1]	Upon adoption of ASU 2016-01 and ASU 2018-02 in the first quarter of 2018, we recognized a $25.0 million cumulative-effect adjustment to the opening balance of AOCI, which represents the after-tax net unrealized gain on our equity portfolio as of December 31, 2017 and the one-time reclassification from AOCI to retained earnings for the stranded tax assets that were created in AOCI from the enactment of Tax Reform. See Note 3. "Adoption of Accounting Pronouncements" above for additional information.

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Dividend reinvestment plan, shares	23,493	28,607	38,741
Stock purchase and compensation plans, shares	540,337	635,521	720,323
Dividends to stockholders, per share	$ 0.74	$ 0.66	$ 0.61
Acquisition of treasury stock, shares	110,398	136,205	152,595
Preferred stock, par value per share	$ 0	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued	0	0	0
Series A Preferred Stock [Member]
Preferred stock, par value per share	$ 0	$ 0	$ 0
Preferred stock, shares authorized	300,000	300,000	300,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net income	$ 178,939	$ 168,826	$ 158,495
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	44,874	52,100	61,671
Stock-based compensation expense	14,507	12,089	10,449
Undistributed (gains) losses of equity method investments	(8,341)	(5,362)	318
Distributions in excess of current year income of equity method investments	2,924	552	0
Net realized and unrealized losses (gains)	54,923	(6,359)	4,937
Loss on disposal of fixed assets	63	998	0
Changes in assets and liabilities:
Increase in reserves for loss and loss expense, net of reinsurance recoverables	168,288	106,226	114,422
Increase in unearned premiums, net of prepaid reinsurance	78,058	79,614	87,716
Decrease in net federal income taxes	2,428	30,918	11,150
Increase in premiums receivable	(23,489)	(65,418)	(66,447)
Increase in deferred policy acquisition costs	(17,557)	(12,491)	(9,405)
Increase in interest and dividends due or accrued	(540)	(1,088)	(1,473)
Decrease in accrued salaries and benefits	(26,418)	(5,714)	(46,536)
Increase in other assets	(372)	(2,643)	(4,979)
(Decrease) increase in other liabilities	(13,343)	27,297	9,191
Net cash provided by operating activities	454,944	379,545	329,509
Investing Activities
Purchase of fixed income securities, held-to-maturity	(7,150)	0	(4,235)
Purchase of fixed income securities, available-for-sale	(2,918,203)	(2,130,362)	(1,982,023)
Purchase of equity securities, available-for-sale		(61,931)	(35,490)
Purchase of equity securities	(94,344)
Purchase of other investments	(68,578)	(55,830)	(66,164)
Purchase of short-term investments	(4,259,734)	(4,280,553)	(3,499,380)
Sale of fixed income securities, available-for-sale	2,030,664	1,197,920	926,470
Sale of short-term investments	4,101,530	4,338,318	3,470,022
Redemption and maturities of fixed income securities, held-to-maturity	12,106	58,832	102,868
Redemption and maturities of fixed income securities, available-for-sale	638,916	555,216	641,524
Sale of equity securities, available-for-sale		37,960	119,617
Sale of equity securities	113,339
Sale of other investments	3,497	0	0
Distributions from other investments	28,379	21,843	24,202
Purchase of property and equipment	(16,110)	(14,071)	(18,147)
Net cash used in investing activities	(435,688)	(332,658)	(320,736)
Financing Activities
Dividends to stockholders	(42,097)	(37,045)	(33,758)
Acquisition of treasury stock	(6,556)	(6,015)	(4,992)
Net proceeds from stock purchase and compensation plans	7,252	7,599	7,811
Proceeds from borrowings	130,000	84,000	165,000
Repayment of borrowings	(130,000)	(84,000)	(115,000)
Excess tax benefits from share-based payment arrangements	0	0	1,819
Repayment of capital lease obligations	(5,646)	(4,121)	(5,002)
Net cash (used in) provided by financing activities	(47,047)	(39,582)	15,878
Net (decrease) increase in cash and restricted cash	(27,791)	7,305	24,651
Cash and restricted cash, beginning of year	44,710	37,405	12,754
Cash and restricted cash, end of year	$ 16,919	$ 44,710	$ 37,405

Organization

Organization	12 Months Ended
	Dec. 31, 2018
Organization [Abstract]
Organization	Organization Selective Insurance Group, Inc., through its subsidiaries, (collectively referred to as “we,” “us,” or “our”) offers standard commercial, standard personal, and excess and surplus ("E&S") lines property and casualty insurance products. Selective Insurance Group, Inc. (referred to as the “Parent”) was incorporated in New Jersey in 1977 and its corporate headquarters is located in Branchville, New Jersey. The Parent’s common stock is publicly traded on the NASDAQ Global Select Market under the symbol “SIGI.” We have provided a glossary of terms as Exhibit 99.1 to this Form 10-K, which defines certain industry-specific and other terms that are used in this Form 10-K. We classify our business into four reportable segments, which are as follows: • Standard Commercial Lines - comprised of insurance products and services provided in the standard marketplace to commercial enterprises, which are typically businesses, non-profit organizations, and local government agencies. • Standard Personal Lines - comprised of insurance products and services, including flood insurance coverage, provided primarily to individuals acquiring coverage in the standard marketplace. • E&S Lines - comprised of insurance products and services provided to customers who have not obtained coverage in the standard marketplace. • Investments - invests the premiums collected by our insurance operations, as well as amounts generated through our capital management strategies, which may include the issuance of debt and equity securities.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Signifcant Accounting Policies	Summary of Significant Accounting Policies (a) Principles of Consolidation The accompanying consolidated financial statements (“Financial Statements”) include the accounts of the Parent and its subsidiaries, and have been prepared in conformity with: (i) U.S. generally accepted accounting principles ("GAAP"); and (ii) the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation. (b) Use of Estimates The preparation of our Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported financial statement balances, as well as the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. (c) Reclassifications Certain amounts in our prior years' Financial Statements and related notes have been reclassified to conform to the 2018 presentation. Specifically, we reclassified restricted cash balances related to our participation in the National Flood Insurance Program ("NFIP") from other assets in our consolidated balance sheet into a separate line item on the face of that statement. Additionally, refer to Note 3. "Adoption of Accounting Pronouncements" below for a discussion of the retroactive restatements that are included in these financial statements in relation to the adoption of new accounting pronouncements for the treatment of restricted cash and distributions from equity method investments on the Consolidated Statements of Cash Flows. (d) Investments Portfolio Composition and Presentation in the Consolidated Balance Sheets Our investment portfolio is primarily comprised of fixed income securities, which represent approximately 89% of our invested assets. We also hold equity securities, short-term investments, and other investments. A description of our portfolio holdings, and the related presentation in our Consolidated Balance Sheets, is provided below. Fixed Income Portfolio We hold the following types of securities in our fixed income securities portfolio: • U.S. government and government agencies; • Foreign government obligations; • State and municipal obligations, including special revenue and general obligation bonds; • Corporate securities, which may include investment grade and below investment grade bonds, bank loan investments, redeemable preferred stock, and non-redeemable preferred stock with certain debt-like characteristics; • Collateralized loan obligations ("CLOs") and other asset-backed securities ("ABS"); • Residential mortgage-backed securities ("RMBS"); and • Commercial mortgage-backed securities ("CMBS"). We have designated approximately 99% of our fixed income securities portfolio as available-for-sale ("AFS"), with the remaining 1% being designated as held-to-maturity ("HTM"), as we have the ability and positive intent to hold these securities to maturity. Our AFS securities are reported at fair value in our consolidated balance sheets, with unrealized gains or losses recognized in accumulated other comprehensive income (loss) ("AOCI"), net of tax. HTM securities are carried at either: (i) amortized cost; or (ii) market value at the date of transfer into the HTM category, adjusted for subsequent amortization. After-tax unrealized gains and losses on securities that were transferred into an HTM designation from an AFS designation, are also included in AOCI. The amortized cost of fixed income securities is adjusted for the amortization of premiums and the accretion of discounts over the expected life of the security using the effective yield method. Callable debt securities held at a premium are amortized to the earliest call date. Premiums and discounts arising from the purchase of RMBS, CMBS, CLOs and other ABS are amortized over the expected life of the security based on future principal payments, giving additional consideration to prepayments. These prepayments are estimated based on historical and projected cash flows. Prepayment assumptions are reviewed quarterly and adjusted to reflect actual prepayments and changes in expectations. Future amortization of any premium and/or discount is adjusted to reflect the revised assumptions. Other Portfolio Holdings Equity securities may include common and non-redeemable preferred stocks. Equity securities with readily determinable fair values are carried at fair value. Certain equity securities without readily determinable fair values are carried at net asset value ("NAV") as a practical expedient. Short-term investments may include certain money market instruments, savings accounts, commercial paper, and debt issues purchased with a maturity of less than one year. We also enter into reverse repurchase agreements that are included in short-term investments. These loans are fully collateralized with high quality, readily marketable instruments at a minimum of 102% of the loan principal. At maturity, we receive principal and interest income on these agreements. All short-term investments are carried at cost, which approximates fair value. Other investments may include alternative investments and other securities. Alternative investments are accounted for using the equity method, with income typically recognized on a one-quarter lag. Other securities are primarily comprised of tax credit investments and equity securities without readily determinable fair values that are not carried at NAV as a practical expedient. These equity securities are carried at cost. Accounting for our tax credit investments is dependent on the type of credit we have purchased, as follows: • Federal low income housing tax credits are accounted for under the proportional amortization method; and • All other tax credits in our investment portfolio are accounted for using the equity method. For federal tax credits accounted for under the equity method, we use the deferral method for recognizing the benefit of the tax credit with the related deferred revenue being recognized in our Consolidated Income Statement as a component of "Federal income tax expense" proportionately over the life of the investment. We evaluate the alternative investments and tax credit investments included in our other investments portfolio to determine whether those investments are variable interest entities ("VIEs") and if so, whether consolidation is required. A VIE is an entity that either has equity investors that lack certain essential characteristics of a controlling financial interest or lack sufficient funds to finance its own activities without financial support provided by other entities. We consider several significant factors in determining if our investments are VIEs and if we are the primary beneficiary, including whether we have: (i) the power to direct activities of the VIE; (ii) the ability to remove the decision maker of the VIE; (iii) the ability to participate in making decisions that are significant to the VIE; and (iv) the obligation to absorb losses and the right to receive benefits that could potentially be significant to the VIE. We have reviewed our alternative and tax credit investments and have concluded that they are VIEs, but that we are not the primary beneficiary and therefore, consolidation is not required. Presentation in the Consolidated Statements of Income Net investment income earned on our Consolidated Statements of Income include the following: • Interest income, as well as amortization and accretion, on fixed income securities; • Dividend income on equity securities; • Interest income on our short-term investments; and • Income recognized on our alternative and other investments accounted for under the equity method of accounting, except for federal tax credits, as discussed below. Income related to federal tax credits (either low income housing tax credits or other federal credits) is recorded in our Consolidated Statements of Income as a component of “Federal income tax expense” proportionately over the life of the investment. Net realized and unrealized gains and losses on our Consolidated Statements of Income include the following: • Realized gain and losses on the disposal of investment securities, which are determined on the basis of the cost of the specific investments sold; • Other-than-temporary impairment ("OTTI") charges that are credit related or related to our intent to sell; and • Changes in unrealized gains or losses on our equity securities that are carried at fair value. On a quarterly basis, we review our investment portfolio for impairments that are other than temporary. The following provides information on this analysis for our fixed income securities and short-term investments, and our other investments. OTTI Charges on Fixed Income Securities and Short-Term Investments We review our fixed income securities and short-term investments that are in an unrealized loss position to determine: (i) if we have the intent to sell the security; (ii) if it is more likely than not that we will be required to sell the security before its anticipated recovery; (iii) if the decline is other than interest-rate related; and (iv) if the decline is other than temporary. Broad changes in the overall market or interest rate environment generally will not lead to a write down. If we determine that we have either the intent or requirement to sell the security, we write down its amortized cost to its fair value through an OTTI charge to earnings. If we do not have either the intent or requirement to sell the security, our evaluation for OTTI may include, but is not limited to, evaluation of the following factors: • Whether the decline appears to be issuer or industry specific; • The degree to which the issuer is current or in arrears in making principal and interest payments on the fixed income security; • The issuer’s current financial condition and ability to make future scheduled principal and interest payments on a timely basis; • Evaluation of projected cash flows; • Buy/hold/sell recommendations published by outside investment advisors and analysts; and • Relevant rating history, analysis, and guidance provided by rating agencies and analysts. To determine if an impairment is other than temporary, we perform assessments that may include, but are not limited to, a discounted cash flow analysis ("DCF") to determine the security's present value of future cash flows. This analysis is also performed on all previously-impaired debt securities that continue to be held by us and all RMBS, CMBS, CLOs and ABS that were not of high credit quality at the date of purchase. Any shortfall in the expected present value of the future cash flows, based on the DCF, from the amortized cost basis of a security is considered a “credit impairment,” with the remaining decline in fair value of a security considered a “non-credit impairment.” Credit impairments are charged to earnings as a component of realized losses, while non-credit impairments are recorded to other comprehensive income ("OCI") as a component of unrealized losses. The discount rate we use in a DCF is the effective interest rate implicit in the security at the date of acquisition for those RMBS, CMBS, CLOs and other ABS that were not of high credit quality at acquisition. For all other securities, we use a discount rate that equals the current yield, excluding the impact of previous OTTI charges, used to accrete the beneficial interest. DCFs may include, but are not necessarily limited to: (i) generating cash flows for each tranche considering tranche-specific data, market data, and other pertinent information, such as the historical performance of the underlying collateral, including net operating income generated by underlying properties, conditional default rate assumptions, loan loss severity assumptions, consensus projections, prepayment projections, and actual pool and collateral information; (ii) identifying applicable benchmark yields; and (iii) applying market-based tranche specific spreads to determine an appropriate yield by incorporating collateral performance, tranche-level attributes, trades, bids, and offers. Non-redeemable preferred stocks that are classified as fixed income securities are evaluated using the OTTI method described above unless the security is below investment grade. In this situation, we would determine: (i) if we do not intend to hold the security to its forecasted recovery; or (ii) if the decline is other than temporary, which includes declines driven by market volatility for which we cannot assert recovery in the near term. If we determine either that we do not intend to hold the security, or the decline is other than temporary, we write down the security's cost to its fair value through an OTTI charge to earnings. OTTI Charges on Other Investments Our evaluation for OTTI of an alternative investment may include, but is not limited to, conversations with the management of the alternative investment concerning the following: • The current investment strategy; • Changes made or future changes to be made to the investment strategy; • Emerging issues that may affect the success of the strategy; and • The appropriateness of the valuation methodology used regarding the underlying investments. Our evaluation for OTTI of our other investments (tax credits and equity securities without a readily determinable fair value for which NAV is not used as a practical expedient) include a qualitative assessment of impairment indicators, which include, but are not limited to, the following: • A significant deterioration in the earnings performance, credit ratings, asset quality, or business prospects of the investee; • A significant adverse change in the regulatory, economic, or technological environment of the investee; • A significant adverse change in the general market condition of either the geographical area or the industry in which the investee operates; • A bona fide offer to purchase, or an offer by the investee to sell, or a completed auction process for the same or similar investment for an amount less than the carrying amount of that investment; and • Factors that raise significant concerns about the investee's ability to continue as a going concern, such as negative cash flows from operations, working capital deficiencies, or noncompliance with statutory capital requirements or debt covenants. If there is a decline in the fair value of an alternative or other investment that we do not intend to hold, or if we determine the decline is other than temporary, we write down the carry value of the investment through an OTTI charge to earnings. (e) Fair Values of Financial Instruments Assets The fair values of our investments are generated using various valuation techniques and are placed into the fair value hierarchy considering the following: (i) the highest priority is given to quoted prices in active markets for identical assets (Level 1); (ii) the next highest priority is given to quoted prices in markets that are not active or inputs that are observable either directly or indirectly, including quoted prices for similar assets in markets that are not active and other inputs that can be derived principally from, or corroborated by, observable market data for substantially the full term of the assets (Level 2); and (iii) the lowest priority is given to unobservable inputs supported by little or no market activity and that reflect our assumptions about the exit price, including assumptions that market participants would use in pricing the asset (Level 3). An asset’s classification within the fair value hierarchy is based on the lowest level of significant input to its valuation. Transfers between levels in the fair value hierarchy are recognized at the end of the reporting period. The techniques used to value our financial assets are as follows: Level 1 Pricing Security Type Methodology Equity Securities; U.S. Treasury Notes Equity and U.S. Treasury Note prices are received from an independent pricing service that are based on observable market transactions. We validate these prices against a second external pricing service, and if established market value comparison thresholds are breached, further analysis is performed to determine the price to be used. Short-Term Investments Short-term investments are carried at cost, which approximates fair value. Given the liquid nature of our short-term investments, we generally validate their fair value by way of active trades within approximately one week of the financial statement close. Level 2 Pricing We utilize a market approach for our Level 2 securities, using primarily matrix pricing models prepared by external pricing services. Matrix pricing models use mathematical techniques to value debt securities by relying on the securities' relationship to other benchmark quoted securities, and not relying exclusively on quoted prices for specific securities, as the specific securities are not always frequently traded. As a matter of policy, we consistently use one pricing service as our primary source and secondary pricing services if prices are not available from the primary pricing service. Fixed income securities portfolio pricing is reviewed for reasonableness in the following ways: (i) comparing our pricing to other third-party pricing services as well as benchmark indexed pricing; (ii) comparing fair value fluctuations between months for reasonableness; and (iii) reviewing stale prices. If further analysis is needed, a challenge is sent to the pricing service for review and confirmation of the price. Further information on our Level 2 asset pricing is included in the following table: Security Type Methodology Corporate Securities including preferred stocks classified as Fixed Income Securities, and U.S. Government and Government Agencies Evaluations include obtaining relevant trade data, benchmark quotes and spreads, and incorporating this information into either spread-based or price-based evaluations as determined by the observed market data. Spread-based evaluations include: (i) creating a range of spreads for relevant maturities of each issuer based on the new issue market, secondary trading, and dealer quotes; and (ii) incorporating option adjusted spreads for issues that have early redemption features. Based on the findings in (i) and (ii) above, final spreads are derived and added to benchmark curves. Price-based evaluations include matching each issue to its best-known market maker and contacting firms that transact in these securities. Obligations of States and Political Subdivisions Evaluations are based on yield curves that are developed based on factors such as: (i) benchmarks to issues with interest rates near prevailing market rates; (ii) established trading spreads over widely-accepted market benchmarks; (iii) yields on new issues; and (iv) market information from third-party sources such as reportable trades, broker-dealers, or issuers. RMBS, CMBS, CLOs and other ABS Evaluations are based on a DCF, including: (i) generating cash flows for each tranche considering tranche-specific data, market data, and other pertinent information, such as historical performance of the underlying collateral, including net operating income generated by the underlying properties, conditional default rate assumptions, loan loss severity assumptions, consensus projections, prepayment projections, and actual pool and loan level collateral information; (ii) identifying applicable benchmark yields; and (iii) applying market-based tranche-specific spreads to determine an appropriate yield by incorporating collateral performance, tranche-level attributes, trades, bids, and offers. Foreign Government Evaluations are performed using a DCF model and by incorporating observed market yields of benchmarks as inputs, adjusting for varied maturities. Level 3 Pricing Less than 1% of our portfolio cannot be priced using our primary or secondary pricing service. At times, we may use valuations performed by the issuer or non-binding broker quotes to determine the fair value of these securities. We internally review these fair value measurements for reasonableness. This review typically includes an analysis of price fluctuations between months with variances over established thresholds being analyzed further. Liabilities The techniques used to value our notes payable are as follows: Level 1 Pricing Security Type Methodology 5.875% Senior Notes Based on the quoted market prices. Level 2 Pricing Security Type Methodology 7.25% Senior Notes; 6.70% Senior Notes Based on matrix pricing models prepared by external pricing services. Borrowings from Federal Home Loan Banks Evaluations are performed using a DCF model based on current borrowing rates provided by the Federal Home Loan Banks that are consistent with the remaining term of the borrowing. (f) Allowance for Uncollectible Accounts We estimate an allowance for uncollectible accounts on our premiums receivable. This allowance is based on historical write-off percentages adjusted for the effects of current and anticipated trends. An account is charged off when we believe it is probable that we will not collect a receivable. In making this determination, we consider information obtained from our efforts to collect amounts due directly or through collection agencies. (g) Share-Based Compensation Share-based compensation consists of all share-based payment transactions in which an entity acquires goods or services by issuing (or offering to issue) its shares, share units, share options, or other equity instruments. The cost resulting from all share-based payment transactions are recognized in the Financial Statements based on the fair value of both equity and liability awards. The fair value is measured at grant date for equity awards, whereas the fair value for liability awards are remeasured at each reporting period. The fair value of both equity and liability awards is recognized over the requisite service period. The requisite service period is typically the lesser of the vesting period or the period of time from the grant date to the date of retirement eligibility. The expense recognized for share-based awards, which, in some cases, contain performance criteria, is based on the number of shares or units expected to be issued at the end of the performance period. We repurchase the Parent’s stock from our employees in connection with tax withholding obligations, as permitted under our stock-based compensation plans. This activity is disclosed in our Consolidated Statements of Stockholders' Equity. (h) Reinsurance Reinsurance recoverable represents estimates of amounts that will be recovered from reinsurers under our various treaties. Generally, amounts recoverable from reinsurers are recognized as assets at the same time and in a manner consistent with the paid and unpaid losses associated with the reinsured policies. We require collateral to secure reinsurance recoverables primarily from our reinsurance carriers that are not authorized, otherwise approved, or certified to do business in one or more of our ten insurance subsidiaries' domiciliary states. Our ten insurance subsidiaries are collectively referred to as the "Insurance Subsidiaries." This collateral is typically in the form of a letter of credit or cash. An allowance for estimated uncollectible reinsurance is recorded based on an evaluation of balances due from reinsurers and other available information, such as each reinsurer's credit rating from A.M. Best Company ("A.M. Best") or Standard & Poor's Rating Services ("S&P"). We charge off reinsurance recoverables on paid losses when it becomes probable that we will not collect the balance. (i) Property and Equipment Property and equipment used in operations, including certain costs incurred to develop or obtain computer software for internal use, are capitalized and carried at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. The following estimated useful lives can be considered as general guidelines: Asset Category Years Computer hardware 3 Computer software 3 to 5 Internally developed software 5 to 10 Software licenses 3 to 5 Furniture and fixtures 10 Buildings and improvements 5 to 40 We recorded depreciation expense of $19.5 million , $17.8 million , and $17.4 million for 2018 , 2017 , and 2016 , respectively. (j) Deferred Policy Acquisition Costs Deferred policy acquisition costs are limited to costs directly related to the successful acquisition of insurance contracts. Costs meeting this definition typically include, among other things, sales commissions paid to our distribution partners, premium taxes, and the portion of employee salaries and benefits directly related to time spent on acquired contracts. These costs are deferred and amortized over the life of the contracts. Accounting guidance requires a premium deficiency analysis to be performed at the level an entity acquires, services, and measures the profitability of its insurance contracts. We currently perform three premium deficiency analyses for our insurance operations, consistent with our reportable segments of Standard Commercial Lines, Standard Personal Lines, and E&S Lines. A combined ratio of over 100% does not necessarily indicate a premium deficiency, as any year's combined ratio includes a portion of underwriting expenses that are expensed at policy inception and therefore are not covered by the remaining unearned premium. In addition, investment income is not contemplated in the combined ratio calculation. There were no premium deficiencies for any of the reported years, as the sum of the anticipated loss and loss expense, unamortized acquisition costs, policyholder dividends, and other expenses for each segment did not exceed that segment’s related unearned premium and anticipated investment income. The investment yields assumed in the premium deficiency assessment for each reporting period, which were based on our actual average investment yield before tax as of the September 30 calculation date, were 3.3% for 2018 , 2.9% for 2017 , and 2.4% for 2016 . (k) Goodwill Goodwill results from business acquisitions where the cost of assets and liabilities acquired exceeds the fair value of those assets and liabilities. A quantitative goodwill impairment analysis is performed if our quarterly qualitative analysis indicates that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. Goodwill is allocated to the reporting units for purposes of these analyses. Based on our analysis at December 31, 2018 , goodwill was not impaired. (l) Reserve for Loss and Loss Expense Reserves for loss and loss expense are comprised of both case reserves on individual claims and reserves for claims incurred but not reported ("IBNR"). Case reserves result from claims that have been reported to one or more of our Insurance Subsidiaries, and are estimated at the amount of the expected ultimate payment. IBNR reserves are established at more aggregated levels than case basis reserves, and include: (i) reserves on IBNR claims; and (ii) provisions for future emergence on known or reopened claims. IBNR reserves are established based on the results of the Insurance Subsidiaries’ internal reserve analysis, supplemented with other internal and external information. The internal reserve analysis is performed quarterly, and relies upon generally accepted actuarial techniques. Such techniques assume that past experience, adjusted for the effects of current developments and anticipated trends, are an appropriate basis for predicting future events. Our analyses rely upon historical paid and case loss and loss expense experience organized by line of business, accident year, and maturity (i.e., “triangles”). Standard actuarial projection methods are applied to this history, producing a set of estimated ultimate loss and loss expenses. Ultimate loss and loss expenses are selected from the various methods, considering the strengths and weaknesses of the methods as they apply to the specific line and accident year. Certain types of exposures do not lend themselves to standard actuarial methods. Examples of these are: • Certain property catastrophe events may be low in frequency and high in severity. These events may affect many insureds simultaneously. Due to the unique nature of these events, ultimate liabilities are estimated for each event, based on surveys of our portfolio of exposures, in conjunction with individual claims estimates. While generally short-tailed, the liabilities associated with these events are subject to a higher degree of uncertainty. We maintain significant reinsurance protection that greatly limits the impact that these extreme events have on net loss and loss expenses. • Some insured events may span multiple years and trigger multiple policies, as in the case of asbestos and environmental claims, where the injury is deemed to occur over an extended period of time. These types of losses often do not lend themselves to traditional actuarial methods. Where we deem appropriate, our experience may be analyzed without differentiating by accident year, using alternative methods and metrics. In these cases, the associated selected ultimate loss and loss expenses are then allocated to the applicable accident years for reporting. • Another example of non-standard methods relate to loss expenses that cannot be attributed to a specific claim (referred to as “unallocated loss expenses”). These expenses are first allocated to line of business, and alternative projection methods are then applied to estimate expenses by calendar year, which are then allocated back to the applicable accident years for reporting. The selected ultimate loss and loss expenses are translated into indicated IBNR reserves, which are then compared to the recorded IBNR reserves. Management's judgment is applied in determining any required adjustments to IBNR and the resulting adjustments are then recorded and assigned or allocated to accident year using the results of the actuarial analysis. While the reserve analysis is the primary basis for determining the recorded IBNR reserves, other internal and external factors are considered. Internal factors include: (i) supplemental data regarding claims reporting and settlement trends; (ii) exposure estimates for reported claims, along with recent development on those estimates with respect to individual large claims and the aggregate of all claims; (iii) the rate at which new large or complex claims are being reported; and (iv) additional trends observed by claims personnel or reported to them by defense counsel. External factors considered include: (i) legislative enactments; (ii) judicial decisions; (iii) legal developments in the determination of liability and the imposition of damages; (iv) social inflation and heightened awareness of sources of liability; and (v) trends in general economic conditions, including the effects of inflation. Loss reserves are estimates, and as such, we also consider a range of possible loss and loss expense reserve estimates. This range is determined at the beginning of each year, using prior year-end data, and reflects the fact that there is no single precise method for estimating the required reserves, due to the many factors that may influence the amounts ultimately paid. Considering the reserve range along with all of the items described above, as well as current market conditions, IBNR estimates are then established and recorded. The combination of the IBNR estimates along with the case reserve estimates on individual claims results in our total reserves for loss and loss expense. These reserves are expected to be sufficient for settling loss and loss expense obligations under our policies on unpaid claims, including changes in the volume of business written, claims frequency and severity, the mix of business, claims processing, and other items that management expects to affect our ultimate settlement of loss and loss expense. However, the ultimate claim settlements may be higher or lower than reserves established. As our experience emerges and other information develops, we revise our reserve estimates accordingly. The changes in these estimates, resulting from the continuous review process and the differences between estimates and ultimate payments, are reflected in the Consolidated Statements of Income for the period in which such estimates are changed. The associated impacts may be material to the results of operations in future periods. We do not discount to present value that portion

Adoption of Accounting Pronounc

Adoption of Accounting Pronouncements	12 Months Ended
	Dec. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Accounting Pronouncements	Adoption of Accounting Pronouncements In January 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-01, Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). ASU 2016-01 provides guidance to improve certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. Specifically the guidance: (i) requires equity securities held in our investment portfolio to be measured at fair value with changes in fair value recognized in earnings; (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; (iii) eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost; (iv) requires the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes; and (v) clarifies that the need for a valuation allowance on a deferred tax asset related to an available-for-sale ("AFS") security should be evaluated with other deferred tax assets. We adopted ASU 2016-01 in the first quarter of 2018 and recognized a $30.7 million cumulative-effect adjustment to the opening balances of accumulated other comprehensive income ("AOCI") and retained earnings, which represents the after-tax net unrealized gain on our equity portfolio as of December 31, 2017. Additionally, beginning in the first quarter of 2018, changes in unrealized gains or losses on this portfolio are no longer recorded to AOCI, but are instead recognized in income through "Net unrealized losses on equity securities" on our Consolidated Statements of Income. See Note 5. "Investments" below for information regarding unrealized equity losses recognized in income for 2018. There were two accounting updates that we adopted with a retrospective transition in the first quarter of 2018 that related to our statements of cash flows. These accounting updates impacted our categorization of distributions from equity method investees (ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15")) and the presentation of restricted cash (ASU 2016-18, Statement of Cash Flows: Restricted Cash ("ASU 2016-18")). These ASUs are discussed below and the discussions are followed with a table presenting the impact of the prior period restatements. In August 2016, the FASB issued ASU 2016-15. As mentioned above, this ASU adds guidance on the categorization of distributions from equity method investees within the statement of cash flows. In accordance with this guidance, we made an accounting policy election to classify these distributions using the cumulative earnings approach. This election resulted in a restatement to operating and investing cash flows as outlined in the table below. ASU 2016-15 also added or clarified guidance on the cash flow classification of certain cash receipts and payments, including, but not limited to: (i) debt prepayment or debt extinguishment costs; (ii) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; and (iii) separately identifiable cash flows and application of the predominance principle. The updated guidance for these topics did not result in any restatements to our statement of cash flows. In November 2016, the FASB issued ASU 2016-18. ASU 2016-18 requires restricted cash and restricted cash equivalents to be included with cash and cash equivalents in the reconciliation of beginning and ending cash on the statements of cash flows. This update also requires a reconciliation of the statement of the cash flows to the balance sheet if the balance sheet includes more than one line item containing cash, cash equivalents, and restricted cash. We have restricted cash related to our participation in the NFIP, which we had previously reported as part of "Other assets" on the Consolidated Balance Sheets. Beginning in the first quarter of 2018, we are reporting restricted cash in its own line item on the Consolidated Balance Sheets to aid in the reconciliation of the amounts presented on the Consolidated Statements of Cash Flows. We have also restated prior year balances on the Consolidated Balance Sheets to conform to the current year presentation. The adoption of this guidance resulted in a restatement of operating cash flows in 2017 and 2016 to remove the impact of the change in restricted cash from operating activities and include the restricted cash balance in the reconciliation of beginning and ending cash balances on the Statements of Cash Flows. In addition, we have included the required reconciliation in Note 4. "Statements of Cash Flows" below. ASU 2016-15 and ASU 2016-18 resulted in the following line item restatements within operating and investing cash flows on the Statements of Cash Flows: December 31, 2017 December 31, 2016 ($ in thousands) Prior to Adoption After Adoption Prior to Adoption After Adoption Undistributed (gains) losses of equity method investments $ (6,393 ) (5,362 ) $ (2,316 ) 318 Distributions in excess of current year income of equity method investments — 552 — — (Increase) decrease in other assets (9,872 ) (2,643 ) (30,071 ) (4,979 ) Net cash provided by operating activities 370,733 379,545 301,783 329,509 Distributions from other investments 23,426 21,843 26,837 24,202 Net cash used in investing activities (331,075 ) (332,658 ) (318,101 ) (320,736 ) In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). ASU 2017-04 eliminates the second step of the two part goodwill impairment test, which required entities to determine the fair value of individual assets and liabilities of a reporting unit to measure the goodwill impairment. Under the new guidance, a goodwill impairment is calculated as the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The amendments in this update are to be applied on a prospective basis for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We adopted ASU 2017-04 in the first quarter of 2018 and it had no impact on us. In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost ("ASU 2017-07"). ASU 2017-07 requires that an employer report a pension plan's service cost in the same line item or line items as other compensation costs arising from services rendered by pertinent employees during the period. ASU 2017-07 also requires that other components of net benefit cost be presented in the income statement separately from the service cost component. If a separate line item or items are not used, the line item or items used in the income statement to present the other components of net benefit cost must be disclosed. ASU 2017-07 was effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods, with early adoption permitted at the beginning of an annual period. We adopted ASU 2017-07 in the first quarter of 2018, but it had no impact on us as our pension plan was frozen as of March 2016 and we have therefore ceased accruing additional service fee costs since that time. In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income ("ASU 2018-02"). ASU 2018-02 allows a one-time reclassification from AOCI to retained earnings for the stranded tax assets that were created in AOCI from the enactment of the Tax Cuts and Jobs Act of 2017 ("Tax Reform"). We adopted ASU 2018-02 in the first quarter of 2018 and recognized a $5.7 million cumulative-effect adjustment for the deferred tax charge to income in the fourth quarter of 2017 that was associated with net unrealized gains on our investment portfolio and pension plan resulting from the enactment of Tax Reform. Pronouncements to be effective in the future The FASB has issued new leasing guidance through ASU 2016-02, Leases , which was issued in February 2016, as well as additional implementation guidance that was issued in 2018 (collectively referred to as "ASU 2016-02"). ASU 2016-02 requires all lessees to recognize assets and liabilities on their balance sheets for the rights and obligations created by leases with terms longer than 12 months. For leases with a term of 12 months or less, an accounting policy election is allowed to recognize lease expense on a straight-line basis over the lease term. Under the new lease guidance, we expect an increase in assets and liabilities as we will recognize operating leases for office space, fleet vehicles, and equipment on our Consolidated Balance Sheets for the first time. ASU 2016-02 allows for certain practical expedients, accounting policy elections, and a transition method election. We currently plan to adopt practical expedients related to reassessing: (i) whether our existing contracts are, or contain, leases; (ii) lease classification for existing leases; and (iii) initial direct costs for existing leases. Additionally, we plan to adopt accounting policy elections to: (i) aggregate lease and non-lease components of a contract into a single lease component; and (ii) expense short-term leases on a straight-line basis over the lease term. We will be adopting ASU 2016-02 effective January 1, 2019 with a cumulative-effect adjustment to the opening balance of retained earnings as of that date. We do not anticipate the impact of this guidance to be material to our financial condition or results of operations, as operating lease right-of-use assets are expected to be approximately $21 million at transition with related lease liabilities of approximately $20 million . The differential of $1 million will be recognized, on an after-tax basis, as a cumulative-effect adjustment to the opening balance of 2019 retained earnings. Financing lease right-of-use assets and the related lease liabilities are expected to be approximately $1 million as of January 1, 2019. In June 2016, the FASB issued ASU 2016-13 , Financial Instruments - Credit Losses (“ASU 2016-13”). ASU 2016-13 will change the way entities recognize impairment of financial assets by requiring immediate recognition of estimated credit losses expected to occur over the remaining life of many financial assets, including, among others, HTM debt securities, trade receivables, and reinsurance recoverables. This ASU will not impact the impairment accounting model for AFS debt securities. ASU 2016-13 requires a valuation allowance to be calculated on these financial assets and that they be presented on the financial statements net of the valuation allowance. The valuation allowance is a measurement of expected losses that is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. This methodology is referred to as the current expected credit loss model. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2018. We are currently evaluating the impact of this guidance on our financial condition and results of operations. In June 2018, the FASB issued ASU 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"). The amendments in ASU 2018-07 expand the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The adoption of this guidance will not have a material impact on our financial condition or results of operations. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement: Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). ASU 2018-13 modifies the disclosure requirements for fair value measurements. The modifications removed the following disclosure requirements: (i) the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy; (ii) the policy for timing of transfers between levels; and (iii) the valuation processes for Level 3 fair value measurements. This ASU added the following disclosure requirements: (i) the changes in unrealized gains and losses for the period included in other comprehensive income ("OCI") for recurring Level 3 fair value measurements held at the end of the reporting period; and (ii) the range and weighted average of significant observable inputs used to develop Level 3 fair value measurements. This update is effective for annual and interim periods beginning after December 15, 2019, with early adoption permitted. As the requirements of this literature are disclosure only, ASU 2018-13 will not impact our financial condition or results of operations. In August 2018, the FASB issued ASU 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General: Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans (“ASU 2018-14”). ASU 2018-14 modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. These modifications include: (i) removing the requirement to disclose the amount in AOCI expected to be recognized as components of net periodic benefit cost over the next fiscal year; and (ii) adding the requirement to disclose an explanation of the reasons for significant gains or losses related to changes in the benefit obligation for the period. This update is effective for fiscal years ending after December 15, 2020, with early adoption permitted. As the requirements of this literature are disclosure only, ASU 2018-14 will not impact our financial condition or results of operations. In August 2018, the FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. This update is effective for annual and interim periods beginning after December 15, 2019, with early adoption permitted. We are currently evaluating the impact of this guidance on our financial condition or results of operations.

Statements of Cash Flow

Statements of Cash Flow	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Statements of Cash Flow	Statements of Cash Flows Supplemental cash flow information for the years ended December 31, 2018, 2017, and 2016 is as follows: ($ in thousands) 2018 2017 2016 Cash paid during the period for: Interest $ 23,992 23,905 22,098 Federal income tax 29,193 62,000 46,405 Non-cash items: Corporate actions related to fixed income securities, AFS 1 52,277 22,511 23,579 Corporate actions related to equity securities 1 944 4,725 3,263 Assets acquired under capital lease arrangements 4,119 278 3,151 Non-cash purchase of property and equipment 291 — 78 1 Examples of corporate actions include exchanges, non-cash acquisitions, and stock-splits. The following table provides a reconciliation of cash and restricted cash reported within the Consolidated Balance Sheets that equate to the amount reported in the Consolidated Statements of Cash Flows: ($ in thousands) December 31, 2018 December 31, 2017 Cash $ 505 534 Restricted cash 16,414 44,176 Total cash and restricted cash shown in the Statements of Cash Flows $ 16,919 44,710 Amounts included in restricted cash represent cash received from the NFIP, which is restricted to pay flood claims under the Write Your Own Program.

Investments

Investments	12 Months Ended
	Dec. 31, 2018
Investments [Abstract]
Investments	Investments (a) Net unrealized gains on investments included in OCI by asset class were as follows for the years ended December 31, 2018, 2017, and 2016 : ($ in thousands) 2018 2017 2016 AFS securities: Fixed income securities $ 2,302 85,806 38,781 Equity securities — 38,894 25,864 Total AFS securities 2,302 124,700 64,645 HTM securities: Fixed income securities 89 (21 ) 159 Total HTM securities 89 (21 ) 159 Total net unrealized gains 2,391 124,679 64,804 Deferred income tax (502 ) (44,103 ) (22,681 ) Net unrealized gains, net of deferred income tax 1,889 80,576 42,123 Cumulative effect adjustment due to accounting change for equity unrealized 1 30,726 — — Cumulative effect adjustment due to accounting changes due to accounting change for stranded tax assets 1 (17,920 ) — — Increase (decrease) in net unrealized gains in OCI, net of deferred income tax $ (65,881 ) 38,453 (2,873 ) 1 Upon adoption of ASU 2016-01, we recognized a $30.7 million cumulative-effect adjustment to the opening balance of AOCI, which represents the after-tax net unrealized gain on our equity portfolio as of December 31, 2017 . Additionally, upon adoption of ASU 2018-02, we recognized a one-time reclassification from AOCI to retained earnings for $17.9 million representing the stranded tax assets related to our investment portfolio that were created in AOCI from the enactment of Tax Reform. See Note 3. "Adoption of Accounting Pronouncements" above for additional information. (b) Information regarding our HTM fixed income securities as of December 31, 2018 and December 31, 2017 was as follows: December 31, 2018 Net Unrealized Unrecognized Unrecognized Amortized Gains Carrying Holding Holding Fair ($ in thousands) Cost (Losses) Value Gains Losses Value Obligations of state and political subdivisions $ 17,431 39 17,470 504 (5 ) 17,969 Corporate securities 19,590 50 19,640 855 (147 ) 20,348 Total HTM fixed income securities $ 37,021 89 37,110 1,359 (152 ) 38,317 December 31, 2017 Net Unrealized Unrecognized Unrecognized Amortized Gains Carrying Holding Holding Fair ($ in thousands) Cost (Losses) Value Gains Losses Value Obligations of state and political subdivisions 25,154 84 25,238 1,023 — 26,261 Corporate securities 16,996 (105 ) 16,891 1,003 (55 ) 17,839 Total HTM fixed income securities $ 42,150 (21 ) 42,129 2,026 (55 ) 44,100 Unrecognized holding gains and losses of HTM securities are not reflected in the Financial Statements, as they represent fair value fluctuations from the date a security is designated as HTM through the date of the balance sheet. (c) Information regarding our AFS securities as of December 31, 2018 and December 31, 2017 were as follows: December 31, 2018 Cost/ Amortized Unrealized Unrealized Fair ($ in thousands) Cost Gains Losses Value AFS fixed income securities: U.S. government and government agencies $ 120,092 1,810 (592 ) 121,310 Foreign government 23,202 36 (107 ) 23,131 Obligations of states and political subdivisions 1,121,615 19,485 (2,631 ) 1,138,469 Corporate securities 1,639,852 5,521 (27,965 ) 1,617,408 CLO and other ABS 720,193 4,112 (6,943 ) 717,362 CMBS 527,409 3,417 (3,748 ) 527,078 RMBS 1,118,435 12,988 (3,081 ) 1,128,342 Total AFS fixed income securities $ 5,270,798 47,369 (45,067 ) 5,273,100 December 31, 2017 Cost/ Amortized Unrealized Unrealized Fair ($ in thousands) Cost Gains Losses Value AFS fixed income securities: U.S. government and government agencies $ 49,326 647 (233 ) 49,740 Foreign government 18,040 526 (11 ) 18,555 Obligations of states and political subdivisions 1,539,307 44,245 (582 ) 1,582,970 Corporate securities 1,588,339 30,891 (1,762 ) 1,617,468 CLO and other ABS 789,152 6,508 (202 ) 795,458 CMBS 382,727 1,563 (841 ) 383,449 RMBS 709,825 6,487 (1,430 ) 714,882 Total AFS fixed income securities 5,076,716 90,867 (5,061 ) 5,162,522 AFS equity securities: Common stock 129,696 38,287 (226 ) 167,757 Preferred stock 14,115 904 (71 ) 14,948 Total AFS equity securities 143,811 39,191 (297 ) 182,705 Total AFS securities $ 5,220,527 130,058 (5,358 ) 5,345,227 Unrealized gains and losses of AFS securities represent fair value fluctuations from the later of: (i) the date a security is designated as AFS; or (ii) the date that an OTTI charge is recognized on an AFS security, through the date of the balance sheet. These unrealized gains and losses are recorded in AOCI on the Consolidated Balance Sheets. As of the first quarter of 2018, equity securities are no longer required to be included in the table above under new accounting guidance that provides that unrealized gains and losses on equity securities should no longer be recognized in AOCI, but instead recognized though income. Refer to Note 3. "Adoption of Accounting Pronouncements" for additional information regarding the adoption of ASU 2016-01. (d) The severity of impairment on the securities in an unrealized/unrecognized loss position averaged approximately 2% of amortized cost at December 31, 2018 and approximately 1% at December 31, 2017 . Quantitative information regarding unrealized losses on our AFS portfolio is provided below. Our HTM portfolio had $0.2 million in unrealized/unrecognized losses at December 31, 2018 and $0.1 million in unrealized/unrecognized losses at December 31, 2017 . December 31, 2018 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Unrealized AFS fixed income securities: U.S. government and government agencies $ 6,693 (174 ) 23,163 (418 ) 29,856 (592 ) Foreign government 12,208 (93 ) 1,482 (14 ) 13,690 (107 ) Obligations of states and political subdivisions 196,798 (2,074 ) 42,821 (557 ) 239,619 (2,631 ) Corporate securities 1,041,952 (23,649 ) 78,953 (4,316 ) 1,120,905 (27,965 ) CLO and other ABS 516,106 (6,750 ) 16,800 (193 ) 532,906 (6,943 ) CMBS 229,338 (2,548 ) 66,294 (1,200 ) 295,632 (3,748 ) RMBS 139,338 (1,660 ) 45,661 (1,421 ) 184,999 (3,081 ) Total AFS fixed income securities $ 2,142,433 (36,948 ) 275,174 (8,119 ) 2,417,607 (45,067 ) December 31, 2017 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Unrealized AFS fixed income securities: U.S. government and government agencies $ 23,516 (233 ) 250 — 23,766 (233 ) Foreign government 1,481 (11 ) — — 1,481 (11 ) Obligations of states and political subdivisions 107,514 (422 ) 14,139 (160 ) 121,653 (582 ) Corporate securities 238,326 (1,744 ) 3,228 (18 ) 241,554 (1,762 ) CLO and other ABS 74,977 (196 ) 1,655 (6 ) 76,632 (202 ) CMBS 154,267 (773 ) 5,214 (68 ) 159,481 (841 ) RMBS 269,485 (1,285 ) 11,200 (145 ) 280,685 (1,430 ) Total AFS fixed income securities 869,566 (4,664 ) 35,686 (397 ) 905,252 (5,061 ) AFS equity securities: Common stock 4,727 (226 ) — — 4,727 (226 ) Preferred stock 3,833 (71 ) — — 3,833 (71 ) Total AFS equity securities 8,560 (297 ) — — 8,560 (297 ) Total AFS securities $ 878,126 (4,961 ) 35,686 (397 ) 913,812 (5,358 ) The increase in the less than 12 months unrealized loss position was due to higher interest rates, with a 60-basis point increase in the 2-year U.S. Treasury Note yields and a 28-point basis increase in the 10-year U.S. Treasury Note yields during 2018. We do not currently intend to sell any of the securities in the tables above, nor will we be required to sell any of these securities. Considering these factors and our review of these securities under our OTTI policy as described in Note 2,“Summary of Significant Accounting Policies” of this Form 10-K, we have concluded that they are temporarily impaired as we believe: (i) they will mature at par value; (ii) they have not incurred a credit impairment; and (iii) future values of these securities will fluctuate with changes in interest rates. This conclusion reflects our current judgment as to the financial position and future prospects of the entity that issued the investment security and underlying collateral. (e) Fixed income securities at December 31, 2018 , by contractual maturity are shown below. Mortgage-backed securities are included in the maturity tables using the estimated average life of each security. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Listed below are the contractual maturities of fixed income securities at December 31, 2018 : AFS HTM ($ in thousands) Fair Value Carrying Value Fair Value Due in one year or less $ 188,309 13,502 13,693 Due after one year through five years 2,040,395 17,308 18,260 Due after five years through 10 years 2,863,528 6,300 6,364 Due after 10 years 180,868 — — Total fixed income securities $ 5,273,100 37,110 38,317 (f) The following table summarizes our other investment portfolio by strategy: Other Investments December 31, 2018 December 31, 2017 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Carrying Value Remaining Maximum 1 Alternative Investments Private equity $ 84,352 93,688 178,040 52,251 99,026 151,277 Private credit 41,682 81,453 123,135 37,743 94,959 132,702 Real assets 27,862 27,129 54,991 25,379 27,014 52,393 Total alternative investments 153,896 202,270 356,166 115,373 220,999 336,372 Other securities 2 25,042 — 25,042 16,895 — 16,895 Total other investments $ 178,938 202,270 381,208 132,268 220,999 353,267 1 The maximum exposure to loss includes both the carrying value of these investments and the related unfunded commitments. In addition, tax credits that have been previously recognized in Other securities are subject to the risk of recapture, which we do not consider significant. 2 Other securities primarily consists of tax credit investments. We have reviewed various investments included in the table above and have concluded that they are VIEs, but that we are not the primary beneficiary and therefore, consolidation is not required. We do not have a future obligation to fund losses or debts on behalf of these investments; however, we are contractually committed to make additional investments up to the remaining commitment outlined above. We have not provided any non-contractual financial support at any time during 2018 or 2017. The following is a description of our alternative investment strategies: Our private equity strategy includes the following: • Primary Private Equity : This strategy makes private equity investments, primarily in established large and middle market companies across diverse industries globally. • Secondary Private Equity : This strategy purchases seasoned private equity funds from investors desiring liquidity prior to normal fund termination. Investments are made across all sectors of the private equity market, including leveraged buyouts ("LBO"), venture capital, distressed securities, mezzanine financing, real estate, and infrastructure. • Venture Capital : In general, these investments are made principally by investing in equity securities of privately-held corporations, for long-term capital appreciation. This strategy makes private equity investments in growth equity and buyout partnerships. Our private credit strategy includes the following: • Middle Market Lending : This strategy provides privately negotiated loans to U.S. middle market companies. Typically, these are floating rate, senior secured loans diversified across industries. Loans can be made to private equity sponsor-backed companies or non-sponsored companies to finance LBOs, recapitalizations, and acquisitions. • Mezzanine Financing : This strategy provides privately negotiated fixed income securities, generally with an equity component, to LBO firms and private and publicly traded large, mid, and small-cap companies to finance LBOs, recapitalizations, and acquisitions. • Distressed Debt : This strategy makes direct and indirect investments in debt and equity securities of companies that are experiencing financial and/or operational distress. Investments include buying indebtedness of bankrupt or financially troubled companies, small balance loan portfolios, special situations and capital structure arbitrage trades, commercial real estate mortgages, and similar non-U.S. securities and debt obligations. Our real assets strategy includes the following: • Energy & Power Generation : This strategy makes energy and power generation investments in cash flow generating infrastructure assets. Energy investments are made in a variety of industries including oil, natural gas, and coal. These investments are diversified across the energy supply chain and include assets in the exploration and production, pipeline, and refining sectors. Power generation includes investments in: (i) conventional power, such as natural gas and oil; (ii) renewable power, such as wind and solar; and (iii) electric transmission and distribution. • Real Estate : This strategy invests in real estate in North America, Europe, and Asia via direct property ownership, joint ventures, mortgages, and investments in equity and debt instruments. Our alternative investment strategies generally employ low or moderate levels of leverage and may use hedging to reduce foreign exchange or interest rate volatility. At this time, our alternative investment strategies do not include hedge funds. We typically cannot redeem our investments with the general partners of these investments; however, occasionally these partnerships can be traded on the secondary market. Once liquidation is triggered by clauses within the limited partnership agreements or at the funds’ stated end date, we will receive our final allocation of capital and any earned appreciation of the underlying investments, assuming we have not divested ourselves of our partnership interests prior to that time. We currently receive distributions from these alternative investments through the realization of the underlying investments or income generated in the limited partnerships. The following tables set forth summarized financial information for our other investments portfolio, including the portion not owned by us. The investments are carried under the equity method of accounting. The last line in the income statement information table below reflects our share of the aggregate income, which is the portion included in our Financial Statements. As the majority of these investments report results to us on a one quarter lag, the summarized financial statement information is as of, and for the 12-month period ended, September 30: Balance Sheet Information September 30, ($ in millions) 2018 2017 Investments $ 28,292 21,046 Total assets 30,377 22,357 Total liabilities 4,532 4,767 Total partners’ capital 25,845 17,590 Income Statement Information 12 months ended September 30, ($ in millions) 2018 2017 2016 Net investment income (loss) $ 134 (143 ) (44 ) Realized gains 1,981 325 1,374 Net change in unrealized appreciation (depreciation) 1,303 2,894 (719 ) Net income $ 3,418 3,076 611 Insurance Subsidiaries' alternative investments income (loss) 17.6 12.7 3.1 (g) We did not have exposure to any credit concentration risk of a single issuer greater than 10% of our stockholders' equity, other than certain U.S. government agencies, as of December 31, 2018 or December 31, 2017 . (h) We have pledged certain AFS fixed income securities as collateral related to our relationships with the Federal Home Loan Bank of Indianapolis ("FHLBI") and the Federal Home Loan Bank of New York ("FHLBNY"). In addition, certain securities were on deposit with various state and regulatory agencies at December 31, 2018 to comply with insurance laws. We retain all rights regarding all securities pledged as collateral. The following table summarizes the market value of these securities at December 31, 2018 : ($ in millions) FHLBI Collateral FHLBNY Collateral State and Regulatory Deposits Total U.S. government and government agencies $ — — 22.5 22.5 Obligations of states and political subdivisions — — 3.9 3.9 Corporate securities — — 0.3 0.3 CMBS 7.2 18.1 — 25.3 RMBS 58.0 45.5 — 103.5 Total pledged as collateral $ 65.2 63.6 26.7 155.5 (i) The components of pre-tax net investment income earned were as follows: ($ in thousands) 2018 2017 2016 Fixed income securities $ 178,104 153,230 129,306 Equity securities 7,764 6,442 7,368 Short-term investments 3,472 1,526 686 Other investments 17,799 12,871 2,940 Investment expenses (11,803 ) (12,187 ) (9,546 ) Net investment income earned $ 195,336 161,882 130,754 (j) The following tables summarize OTTI by asset type for the periods indicated: 2018 Recognized in Earnings ($ in thousands) Gross Included in OCI AFS fixed income securities: Corporate securities $ 1,783 — 1,783 RMBS 2,903 — 2,903 Total AFS fixed income securities 4,686 — 4,686 Other investments 1,893 — 1,893 Total OTTI losses $ 6,579 — 6,579 2017 Recognized in Earnings ($ in thousands) Gross Included in OCI AFS fixed income securities: U.S. government and government agencies $ 36 — 36 Obligations of states and political subdivisons 612 — 612 Corporate securities 587 — 587 CLO and other ABS 96 — 96 CMBS 670 — 670 RMBS 1,183 (36 ) 1,219 Total AFS fixed income securities 3,184 (36 ) 3,220 AFS equity securities: Common stock 1,435 — 1,435 Total AFS equity securities 1,435 — 1,435 Other investments 190 — 190 Total OTTI losses $ 4,809 (36 ) 4,845 2016 Recognized in Earnings ($ in thousands) Gross Included in OCI AFS fixed income securities: Obligations of states and political subdivisons $ 2,797 — 2,797 CLO and other ABS 19 — 19 Corporate securities 1,880 — 1,880 CMBS 220 — 220 RMBS 275 10 265 Total AFS fixed income securities 5,191 10 5,181 AFS equity securities: Common stock 3,316 — 3,316 Preferred stock 2 — 2 Total AFS equity securities 3,318 — 3,318 Total OTTI losses $ 8,509 10 8,499 (k) Net realized and unrealized gains and losses included the following: ($ in thousands) 2018 2017 2016 Net realized (losses) gains on the disposals of securities: Fixed income securities $ (34,953 ) 6,944 (3,668 ) Equity securities 18,695 4,629 7,244 Short-term investments (3 ) (4 ) (13 ) Other investments (2,714 ) (365 ) (1 ) Net realized (losses) gains on the disposal of securities (18,975 ) 11,204 3,562 OTTI charges (6,579 ) (4,845 ) (8,499 ) Net realized (losses) gains (25,554 ) 6,359 (4,937 ) Unrealized (losses) recognized in income on equity securities 1 (29,369 ) — — Total net realized and unrealized investment (losses) gains $ (54,923 ) 6,359 (4,937 ) 1 Includes unrealized holding gains (losses) of: (i) $(3.1) million on equity securities remaining in our portfolio as of December 31, 2018; and (ii) $(26.3) million on equity securities sold in 2018. The components of net realized (losses) gains on disposals were as follows: ($ in thousands) 2018 2017 2016 HTM fixed income securities Gains $ 2 44 3 Losses — (1 ) (1 ) AFS fixed income securities Gains 5,460 10,193 7,741 Losses (40,415 ) (3,292 ) (11,411 ) Equity securities Gains 23,203 5,829 8,108 Losses (4,508 ) (1,200 ) (864 ) Short-term investments Gains 7 2 — Losses (10 ) (6 ) (13 ) Other investments Gains — 494 3 Losses (2,714 ) (859 ) (4 ) Total net realized investment (losses) gains $ (18,975 ) 11,204 3,562 Realized gains and losses on the sale of investments are determined on the basis of the cost of the specific investments sold. Proceeds from the sale of AFS fixed income securities were $2,030.7 million , $1,197.9 million , and $926.5 million in 2018 , 2017 , and 2016 , respectively. Proceeds from sale of equity securities were $113.3 million , $38.0 million , and $119.6 million in 2018, 2017, and 2016, respectively. Net realized (losses) gains in the table above were driven by the following: • 2018 : Higher trading volume driven by opportunistic sales in both our fixed income securities and equity portfolios. • 2017 : Higher trading volume in our fixed income securities portfolio related to a more active external investment management approach and opportunistic sales in our equity portfolio. 2016 : A repositioning of our equity portfolio, partially offset by net losses in our AFS fixed income portfolio related to the change in our strategy to more actively manage this portfolio.

Comprehensive Income

Comprehensive Income	12 Months Ended
	Dec. 31, 2018
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Comprehensive Income	Comprehensive Income (a) The components of comprehensive income, both gross and net of tax, for 2018 , 2017 , and 2016 were as follows: 2018 ($ in thousands) Gross Tax Net Net income $ 211,721 32,782 178,939 Components of OCI: Unrealized (losses) gains on investment securities : Unrealized holding losses during the year (123,145 ) (25,861 ) (97,284 ) Amounts reclassified into net income: HTM securities 110 23 87 Realized losses on AFS securities 39,641 8,325 31,316 Net unrealized losses (83,394 ) (17,513 ) (65,881 ) Defined benefit pension and post-retirement plans: Net actuarial loss (11,273 ) (2,367 ) (8,906 ) Amounts reclassified into net income: Net actuarial loss 2,127 447 1,680 Defined benefit pension and post-retirement plans (9,146 ) (1,920 ) (7,226 ) Other comprehensive loss (92,540 ) (19,433 ) (73,107 ) Comprehensive income $ 119,181 13,349 105,832 2017 ($ in thousands) Gross Tax Net Net income $ 261,968 93,142 168,826 Components of OCI: Unrealized gains (losses) on investment securities : Unrealized holding gains during the year 66,894 23,879 43,015 Non-credit portion of OTTI recognized in OCI 36 13 23 Amounts reclassified into net income: HTM securities (179 ) (63 ) (116 ) Non-credit OTTI 104 36 68 Realized gains on AFS securities (6,979 ) (2,442 ) (4,537 ) Net unrealized gains 59,876 21,423 38,453 Defined benefit pension and post-retirement plans: Net actuarial loss (4,684 ) (984 ) (3,700 ) Amounts reclassified into net income: Net actuarial loss 2,102 735 1,367 Defined benefit pension and post-retirement plans (2,582 ) (249 ) (2,333 ) Other comprehensive income 57,294 21,174 36,120 Comprehensive income $ 319,262 114,316 204,946 2016 ($ in thousands) Gross Tax Net Net income $ 219,955 61,460 158,495 Components of OCI: Unrealized (losses) gains on investment securities : Unrealized holding losses during the year (9,195 ) (3,218 ) (5,977 ) Non-credit portion of OTTI recognized in OCI (10 ) (4 ) (6 ) Amounts reclassified into net income: HTM securities (141 ) (49 ) (92 ) Non-credit OTTI 213 75 138 Realized losses on AFS securities 4,713 1,649 3,064 Net unrealized losses (4,420 ) (1,547 ) (2,873 ) Defined benefit pension and post-retirement plans: Net actuarial loss (12,079 ) (4,227 ) (7,852 ) Amounts reclassified into net income: Net actuarial loss 6,462 2,262 4,200 Defined benefit pension and post-retirement plans (5,617 ) (1,965 ) (3,652 ) Other comprehensive loss (10,037 ) (3,512 ) (6,525 ) Comprehensive income $ 209,918 57,948 151,970 (b) The balances of, and changes in, each component of AOCI (net of taxes) as of December 31, 2018 and 2017 were as follows: Net Unrealized (Loss) Gain on Investment Securities Defined Benefit Pension and Post-retirement Plans ($ in thousands) OTTI Related HTM Related All Other Investments Subtotal Total AOCI Balance, December 31, 2016 $ (150 ) 102 42,170 42,122 (58,072 ) (15,950 ) OCI before reclassifications 23 — 43,015 43,038 (3,700 ) 39,338 Amounts reclassified from AOCI 68 (116 ) (4,537 ) (4,585 ) 1,367 (3,218 ) Net current period OCI 91 (116 ) 38,478 38,453 (2,333 ) 36,120 Balance, December 31, 2017 (59 ) (14 ) 80,648 80,575 (60,405 ) 20,170 Cumulative effect adjustments 1 (12 ) (2 ) (12,792 ) (12,806 ) (12,213 ) (25,019 ) Balance: December 31, 2017 as adjusted $ (71 ) (16 ) 67,856 67,769 (72,618 ) (4,849 ) OCI before reclassifications — — (97,284 ) (97,284 ) (8,906 ) (106,190 ) Amounts reclassified from AOCI — 87 31,316 31,403 1,680 33,083 Net current period OCI — 87 (65,968 ) (65,881 ) (7,226 ) (73,107 ) Balance, December 31, 2018 $ (71 ) 71 1,888 1,888 (79,844 ) (77,956 ) 1 Upon adoption of ASU 2016-01 and ASU 2018-02 in the first quarter of 2018, we recognized a $25.0 million cumulative-effect adjustment to the opening balance of AOCI, which represents the after-tax net unrealized gain on our equity portfolio as of December 31, 2017 and the one-time reclassification from AOCI to retained earnings for the stranded tax assets that were created in AOCI from the enactment of Tax Reform. See Note 3. "Adoption of Accounting Pronouncements" above for additional information. The reclassifications out of AOCI are as follows: ($ in thousands) Year ended December 31, 2018 Year ended December 31, 2017 Affected Line Item in the Consolidated Statements of Income OTTI related Non-credit OTTI on disposed securities $ — 104 Net realized and unrealized (losses) gains — 104 Income before federal income tax — (36 ) Total federal income tax expense — 68 Net income HTM related Unrealized losses on HTM disposals 137 32 Net realized and unrealized (losses) gains Amortization of net unrealized gains on HTM securities (27 ) (211 ) Net investment income earned 110 (179 ) Income before federal income tax (23 ) 63 Total federal income tax expense 87 (116 ) Net income Realized losses (gains) on AFS Realized losses (gains) on AFS disposals 39,641 (6,979 ) Net realized and unrealized (losses) gains 39,641 (6,979 ) Income before federal income tax (8,325 ) 2,442 Total federal income tax expense 31,316 (4,537 ) Net income Defined benefit pension and post-retirement life plans Net actuarial loss 450 450 Loss and loss expense incurred 1,677 1,652 Other insurance expenses Total defined benefit pension and post-retirement life 2,127 2,102 Income before federal income tax (447 ) (735 ) Total federal income tax expense 1,680 1,367 Net income Total reclassifications for the period $ 33,083 (3,218 ) Net income

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following table presents the carrying amounts and estimated fair values of our financial instruments as of December 31, 2018 and 2017 : December 31, 2018 December 31, 2017 ($ in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial Assets Fixed income securities: HTM $ 37,110 38,317 42,129 44,100 AFS 5,273,100 5,273,100 5,162,522 5,162,522 Equity securities 147,639 147,639 182,705 182,705 Short-term investments 323,864 323,864 165,555 165,555 Long-term debt: 7.25% Senior Notes 49,907 57,032 49,904 61,391 6.70% Senior Notes 99,462 107,075 99,446 116,597 5.875% Senior Notes 185,000 177,230 185,000 186,332 1.61% Borrowings from FHLBNY 25,000 24,218 25,000 24,270 1.56% Borrowings from FHLBNY 25,000 24,162 25,000 24,210 3.03% Borrowings from FHLBI 60,000 58,905 60,000 60,334 Subtotal long-term debt 444,369 448,622 444,350 473,134 Unamortized debt issuance costs (4,829 ) (5,234 ) Total long-term debt $ 439,540 439,116 For discussion regarding the fair value techniques of our financial instruments, refer to Note 2. "Summary of Significant Accounting Policies" in this Form 10-K. The following tables provide quantitative disclosures of our financial assets that were measured and recorded at fair value at December 31, 2018 and 2017 : December 31, 2018 Fair Value Measurements Using ($ in thousands) Assets Measured at Fair Value Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) 1 Significant Other Observable Inputs (Level 2) 1 Significant Unobservable Inputs (Level 3) Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 121,310 78,381 42,929 — Foreign government 23,131 — 23,131 — Obligations of states and political subdivisions 1,138,469 — 1,138,469 — Corporate securities 1,617,408 — 1,617,408 — CLO and other ABS 717,362 — 709,953 7,409 CMBS 527,078 — 527,078 — RMBS 1,128,342 — 1,128,342 — Total AFS fixed income securities 5,273,100 78,381 5,187,310 7,409 Equity securities: Common stock 2 144,727 107,397 — — Preferred stock 2,912 2,912 — — Total equity securities 147,639 110,309 — — Short-term investments 323,864 321,370 2,494 — Total assets measured at fair value $ 5,744,603 510,060 5,189,804 7,409 December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets Measured at Fair Value Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) 1 Significant Other Observable Inputs (Level 2) 1 Significant Unobservable Inputs (Level 3) Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 49,740 24,652 25,088 — Foreign government 18,555 — 18,555 — Obligations of states and political subdivisions 1,582,970 — 1,582,970 — Corporate securities 1,617,468 — 1,617,468 — CLO and other ABS 795,458 — 795,458 — CMBS 383,449 — 376,895 6,554 RMBS 714,882 — 714,882 — Total AFS fixed income securities 5,162,522 24,652 5,131,316 6,554 AFS equity securities: Common stock 167,757 138,640 — 5,398 Preferred stock 14,948 14,948 — — Total AFS equity securities 182,705 153,588 — 5,398 Total AFS securities 5,345,227 178,240 5,131,316 11,952 Short-term investments 165,555 165,555 — — Total assets measured at fair value $ 5,510,782 343,795 5,131,316 11,952 1 There were no transfers of securities between Level 1 and Level 2. 2 In accordance with ASU 2015-07, investments amounting to $37.3 million and $23.7 million at December 31, 2018 and December 31, 2017, respectively, were measured at fair value using the net asset value per share (or its practical expedient) and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to total assets measured at fair value. The following table provides a summary of the changes in the fair value of securities measured using Level 3 inputs and related quantitative information during 2018 : 2018 ($ in thousands) CMBS CLO and Other ABS Common Stock Total Fair value, December 31, 2017 $ 6,554 — 5,398 11,952 Total net (losses) gains for the period included in: OCI — — — — Net income — — — — Purchases — 7,409 — 7,409 Sales — — — — Issuances — — — — Settlements — — — — Transfers into Level 3 — — — — Transfers out of Level 3 (6,554 ) — (5,398 ) (11,952 ) Fair value, December 31, 2018 $ — 7,409 — 7,409 The following tables provide quantitative information regarding our financial assets and liabilities that were not measured, but were disclosed at fair value at December 31, 2018 and 2017 : December 31, 2018 Fair Value Measurements Using ($ in thousands) Assets/Liabilities Disclosed at Fair Value Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets HTM: Obligations of states and political subdivisions $ 17,969 — 17,969 — Corporate securities 20,348 — 20,348 — Total HTM fixed income securities $ 38,317 — 38,317 — Financial Liabilities Long-term debt: 7.25% Senior Notes $ 57,032 — 57,032 — 6.70% Senior Notes 107,075 — 107,075 — 5.875% Senior Notes 177,230 177,230 — — 1.61% Borrowings from FHLBNY 24,218 — 24,218 — 1.56% Borrowings from FHLBNY 24,162 — 24,162 — 3.03% Borrowings from FHLBI 58,905 — 58,905 — Total long-term debt $ 448,622 177,230 271,392 — December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets/Liabilities Disclosed at Fair Value Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets HTM: Obligations of states and political subdivisions $ 26,261 — 26,261 — Corporate securities 17,839 — 12,306 5,533 Total HTM fixed income securities $ 44,100 — 38,567 5,533 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 61,391 — 61,391 — 6.70% Senior Notes 116,597 — 116,597 — 5.875% Senior Notes 186,332 186,332 — — 1.61% Borrowings from FHLBNY 24,270 — 24,270 — 1.56% Borrowings from FHLBNY 24,210 — 24,210 — 3.03% Borrowings from FHLBI 60,334 — 60,334 — Total long-term debt $ 473,134 186,332 286,802 —

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2018
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance Our Financial Statements reflect the effects of assumed and ceded reinsurance transactions. Assumed reinsurance refers to the acceptance of certain insurance risks that other insurance entities have underwritten. Ceded reinsurance involves transferring certain insurance risks (along with the related written and earned premiums) that we have underwritten to other insurance companies that agree to share these risks. The primary purpose of ceded reinsurance is to protect the Insurance Subsidiaries from potential losses in excess of the amount that we are prepared to accept. Our major treaties covering property, property catastrophe, and casualty business are excess of loss contracts. In addition, we have an intercompany quota share pooling arrangement and other minor reinsurance treaties. As a Standard Commercial Lines and E&S Lines writer, we are subject to the Terrorism Risk Insurance Program Reauthorization Act ("TRIPRA"), which was extended by Congress to December 31, 2020. TRIPRA requires private insurers and the United States government to share the risk of loss on future acts of terrorism certified by the U.S. Secretary of the Treasury. Under TRIPRA, each participating insurer is responsible for paying a deductible of specified losses before federal assistance is available. This deductible is based on a percentage of the prior year’s applicable Standard Commercial Lines and E&S Lines premiums. In 2019 , our deductible is approximately $339 million . For losses above the deductible, the federal government will pay 81% of losses to an industry limit of $100 billion , and the insurer retains 19% . The federal share of losses will be reduced to 80% in 2020. The Insurance Subsidiaries remain liable to policyholders to the extent that any reinsurer becomes unable to meet their contractual obligations. In addition to this direct counterparty credit risk, we have indirect counterparty credit risk as our reinsurers often enter into their own reinsurance programs, or retrocessions, as part of managing their exposure to large losses. We evaluate and monitor the financial condition of our reinsurers under voluntary reinsurance arrangements to minimize our exposure to significant losses from reinsurer insolvencies. On an ongoing basis, we review amounts outstanding, length of collection period, changes in reinsurer credit ratings, and other relevant factors to determine collectability of reinsurance recoverables. The allowance for uncollectible reinsurance recoverables was $4.5 million at December 31, 2018 and $4.6 million at December 31, 2017 . The following table represents our total reinsurance balances segregated by reinsurer to illustrate our concentration of risk throughout our reinsurance portfolio: As of December 31, 2018 As of December 31, 2017 ($ in thousands) Reinsurance Balances % of Reinsurance Balance Reinsurance Balances % of Reinsurance Balance Total reinsurance recoverables $ 549,172 $ 594,832 Total prepaid reinsurance premiums 157,723 153,493 Total reinsurance balance 706,895 748,325 Federal and state pools 1 : NFIP 170,453 24 % 204,161 27 % New Jersey Unsatisfied Claim Judgment Fund 55,167 7 62,947 9 Other 3,602 1 3,634 — Total federal and state pools 229,222 32 270,742 36 Remaining reinsurance balance $ 477,673 68 $ 477,583 64 Munich Re Group (A.M. Best rated "A+") $ 112,841 16 $ 117,460 16 Hannover Ruckversicherungs AG (A.M. Best rated "A+") 101,835 14 101,652 14 AXIS Reinsurance Company (A.M. Best rated "A+") 69,102 10 62,396 8 Swiss Re Group (A.M. Best rated "A+") 37,519 5 40,772 5 Transatlantic Reinsurance Company (A.M. Best rated “A+”) 17,686 3 13,237 2 Endurance Specialty Ins. LTD. (A.M. Best rated “A+”) 15,163 2 18,469 2 Partner Reinsurance Company of the U.S. (A.M. Best rated “A”) 12,261 2 16,925 2 All other reinsurers 111,266 16 106,672 15 Total reinsurers 477,673 68 % 477,583 64 % Less: collateral 2 (112,201 ) (122,413 ) Reinsurers, net of collateral $ 365,472 $ 355,170 1 Considered to have minimal risk of default. 2 Includes letters of credit, trust funds, and funds held against reinsurance recoverables. Under our reinsurance arrangements, which are prospective in nature, reinsurance premiums ceded are recorded as prepaid reinsurance and amortized over the remaining contract period in proportion to the reinsurance protection provided, or recorded periodically, as per the terms of the contract, in a direct relationship to the gross premium recording. Reinsurance recoveries are recognized as gross losses are incurred. The following table contains a listing of direct, assumed, and ceded reinsurance amounts for premiums written, premiums earned, and loss and loss expense incurred: ($ in thousands) 2018 2017 2016 Premiums written: Direct $ 2,890,633 2,733,459 2,577,259 Assumed 26,250 26,685 28,779 Ceded (402,597 ) (389,503 ) (368,750 ) Net $ 2,514,286 2,370,641 2,237,288 Premiums earned: Direct $ 2,808,764 2,647,488 2,484,715 Assumed 25,831 25,831 28,214 Ceded (398,366 ) (382,292 ) (363,357 ) Net $ 2,436,229 2,291,027 2,149,572 Loss and loss expense incurred: Direct $ 1,706,951 1,570,678 1,560,356 Assumed 21,469 17,588 22,708 Ceded (230,286 ) (243,192 ) (348,267 ) Net $ 1,498,134 1,345,074 1,234,797 The ceded premiums and losses related to our participation in the NFIP, under which 100% of our flood premiums, and loss and loss expense are ceded to the NFIP, are as follows: Ceded to NFIP ($ in thousands) 2018 2017 2016 Ceded premiums written $ (248,053 ) (241,345 ) (232,245 ) Ceded premiums earned (244,238 ) (235,088 ) (227,882 ) Ceded loss and loss expense incurred (144,967 ) (160,922 ) (239,891 )

Reserve for Loss and Loss Expen

Reserve for Loss and Loss Expense	12 Months Ended
	Dec. 31, 2018
Insurance Loss Reserves [Abstract]
Reserve for Loss and Loss Expense	Reserve for Loss and Loss Expense (a) The table below provides a roll forward of reserves for loss and loss expense for beginning and ending reserve balances: ($ in thousands) 2018 2017 2016 Gross reserves for loss and loss expense, at beginning of year $ 3,771,240 3,691,719 3,517,728 Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of year 585,855 611,200 551,019 Net reserves for loss and loss expense, at beginning of year 3,185,385 3,080,519 2,966,709 Incurred loss and loss expense for claims occurring in the: Current year 1,527,997 1,384,266 1,300,565 Prior years (29,863 ) (39,192 ) (65,768 ) Total incurred loss and loss expense 1,498,134 1,345,074 1,234,797 Paid loss and loss expense for claims occurring in the: Current year 573,718 497,486 450,811 Prior years 753,321 742,722 670,176 Total paid loss and loss expense 1,327,039 1,240,208 1,120,987 Net reserves for loss and loss expense, at end of year 3,356,480 3,185,385 3,080,519 Add: Reinsurance recoverable on unpaid loss and loss expense, at end of year 537,388 585,855 611,200 Gross reserves for loss and loss expense at end of year $ 3,893,868 3,771,240 3,691,719 Our net loss and loss expense reserves increased by $171.1 million in 2018 , $104.9 million in 2017 , and $113.8 million in 2016 . The loss and loss expense reserves are net of anticipated recoveries for salvage and subrogation claims, which amounted to $67.7 million for 2018 , $64.8 million for 2017 , and $64.9 million for 2016 . The increase in net loss and loss expense reserves in 2018 was primarily driven by increases in: (i) current year loss costs on our commercial automobile line of business; and (ii) exposure due to premium growth. This increase was partially offset by favorable prior year loss development, largely driven by the workers compensation and general liability lines of business. In 2018 , we experienced overall net favorable prior year loss development of $29.9 million , compared to $ 39.2 million in 2017 and $65.8 million in 2016 . The following table summarizes the prior year development by line of business: (Favorable)/Unfavorable Prior Year Development ($ in millions) 2018 2017 2016 General Liability $ (9.5 ) (48.3 ) (45.0 ) Commercial Automobile 36.7 35.6 25.3 Workers Compensation (83.0 ) (52.3 ) (56.0 ) Businessowners' Policies (1.5 ) 1.9 1.8 Commercial Property 7.5 8.7 0.3 Homeowners 9.8 0.4 1.7 Personal Automobile 3.0 6.7 1.0 E&S Casualty Lines 12.0 10.0 6.0 E&S Property Lines (4.8 ) 0.1 1.2 Other (0.1 ) (2.0 ) (2.1 ) Total $ (29.9 ) (39.2 ) (65.8 ) The Insurance Subsidiaries had $29.9 million of favorable prior accident year development during 2018 , which included $41.5 million of net favorable casualty development and $11.6 million of unfavorable property development. The net favorable casualty reserve development was largely driven by the workers compensation and general liability lines of business. Partially offsetting this net favorable development was $37.5 million of unfavorable casualty development in the commercial auto line of business. In addition, our E&S casualty lines experienced unfavorable development of $12.0 million in 2018 . The majority of the 2018 net favorable development was attributable to our workers compensation line of business, which was impacted by continued favorable medical trends in accident years 2017 and prior. Partially offsetting this was adverse development in the commercial automobile line of business, driven by increases in severities in accident years 2015 through 2017. The Insurance Subsidiaries had $39.2 million of favorable prior accident year development during 2017 , which included $ 48.6 million of net favorable casualty development and $ 9.4 million of unfavorable property development. The net favorable casualty reserve development was largely driven by the workers compensation and general liability lines of business, including products liability and excess liability. Partially offsetting this net favorable development was $36.0 million of unfavorable casualty development in the commercial auto line of business, which was primarily driven by: (i) higher than expected frequencies and severities in accident years 2015 and 2016, and (ii) higher than expected severities in accident years 2012 through 2014. In addition, our E&S casualty lines experienced unfavorable development of $10.0 million in 2017 . The majority of the 2017 net favorable development was attributable to accident years 2014 and prior, driven by the general liability and workers compensation lines of business. This net favorable development was partially offset by unfavorable development in accident years 2015 and 2016 attributable to our commercial auto and E&S casualty lines of business. The unfavorable development in our commercial auto line of business was driven primarily by bodily injury liability for accident years 2012 through 2016, driven by higher than expected frequency and severity. The Insurance Subsidiaries had $ 65.8 million of favorable prior accident year development during 2016 , which included $ 69.0 million of net favorable casualty development and $ 3.2 million of unfavorable property development. The net favorable casualty reserve development was largely driven by the workers compensation and general liability lines of business, including products liability and excess liability. Partially offsetting this net favorable development was $ 25 million of unfavorable casualty development in the commercial automobile line of business. In addition, our E&S casualty lines experienced unfavorable development of $6.0 million in 2016 . The majority of the 2016 net favorable development was attributable to accident years 2013 and prior, driven by the workers compensation and general liability lines of business. This net favorable development was partially offset by unfavorable development in accident years 2014 and 2015 attributable to our commercial auto and E&S casualty lines of business. The unfavorable development in our commercial auto line of business was driven primarily by bodily injury liability for accident years 2014 and 2015. The unfavorable development in accident year 2014 was driven by higher than expected severity, whereas accident year 2015 was driven by higher than expected frequency and severity. (b) Reserves established for liability insurance include exposure to asbestos and environmental claims. These claims have arisen primarily from insured exposures in municipal government, small non-manufacturing commercial risk, and homeowners policies. The emergence of these claims is slow and highly unpredictable. There are significant uncertainties in estimating our exposure to asbestos and environmental claims (for both case and IBNR reserves) resulting from lack of relevant historical data, the delayed and inconsistent reporting patterns associated with these claims, and uncertainty as to the number and identity of claimants and complex legal and coverage issues. Legal issues that arise in asbestos and environmental cases include federal or state venue, choice of law, causation, admissibility of evidence, allocation of damages and contribution among joint defendants, successor and predecessor liability, and whether direct action against insurers can be maintained. Coverage issues that arise in asbestos and environmental cases include the interpretation and application of policy exclusions, the determination and calculation of policy limits, the determination of the ultimate amount of a loss, the extent to which a loss is covered by a policy, if at all, the obligation of an insurer to defend a claim, and the extent to which a party can prove the existence of coverage. Courts have reached different and sometimes inconsistent conclusions on these legal and coverage issues. We do not discount to present value that portion of our loss and loss expense reserves expected to be paid in future periods. The following table details our loss and loss expense reserves for various asbestos and environmental claims: 2018 ($ in millions) Gross Net Asbestos $ 7.3 6.1 Landfill sites 12.2 7.4 Underground storage tanks 10.5 9.3 Total $ 30.0 22.8 Reserves for asbestos and environmental claims are highly uncertain. There are significant uncertainties associated with estimating critical assumptions, such as average clean-up costs, third-party costs, potentially responsible party shares, allocation of damages, litigation and coverage costs, and potential state and federal legislative changes. Estimating IBNR is challenging because of the delayed and inconsistent reporting patterns associated with these claims. Traditional actuarial approaches cannot be applied because past loss history is not necessarily indicative of future behavior. While certain alternative projection models can be applied, such models can produce significantly different results with small changes in assumptions. As a result, reserves for asbestos and environmental require a high degree of judgment. Because of the significant uncertainty in the estimate, we do not calculate an asbestos and environmental loss range. Historically, our asbestos and environmental claims have been significantly lower in volume than many other standard commercial lines carriers since, prior to the introduction of the absolute pollution exclusion endorsement in the mid-1980’s, we were primarily a Standard Personal Lines carrier and therefore do not have broad exposure to asbestos and environmental claims. The following table provides a roll forward of gross and net asbestos and environmental incurred loss and loss expense and related reserves thereon: 2018 2017 2016 ($ in thousands) Gross Net Gross Net Gross Net Asbestos Reserves for loss and loss expense at beginning of year $ 7,577 6,346 7,847 6,615 8,024 6,793 Incurred loss and loss expense — — — — 77 77 Less: loss and loss expense paid (249 ) (249 ) (270 ) (269 ) (254 ) (255 ) Reserves for loss and loss expense at the end of year $ 7,328 6,097 7,577 6,346 7,847 6,615 Environmental Reserves for loss and loss expense at beginning of year $ 20,838 14,866 22,115 16,101 22,387 16,368 Incurred loss and loss expense 3,059 2,877 126 — 1,406 1,303 Less: loss and loss expense paid (1,205 ) (1,057 ) (1,403 ) (1,235 ) (1,678 ) (1,570 ) Reserves for loss and loss expense at the end of year $ 22,692 16,686 20,838 14,866 22,115 16,101 Total Asbestos and Environmental Claims Reserves for loss and loss expense at beginning of year $ 28,415 21,212 29,962 22,716 30,411 23,161 Incurred loss and loss expense 3,059 2,877 126 — 1,483 1,380 Less: loss and loss expense paid (1,454 ) (1,306 ) (1,673 ) (1,504 ) (1,932 ) (1,825 ) Reserves for loss and loss expense at the end of year $ 30,020 22,783 28,415 21,212 29,962 22,716 (c) The following is information about incurred and paid claims development as of December 31, 2018 , net of reinsurance, as well as cumulative claim frequency and the total of IBNR liabilities. During the experience period, we implemented a series of claims-related initiatives and claims management changes. These initiatives focused on claims handling and reserving, medical claims costs, and loss expenses. As a result of these initiatives, several historical patterns have changed and may no longer be appropriate to use as the sole basis for projections. All Lines (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 920,143 941,972 916,691 883,590 870,057 869,927 857,960 853,401 848,413 846,017 34,771 85,707 2010 950,114 973,742 977,959 956,600 943,118 922,404 915,131 907,074 904,561 42,224 94,400 2011 1,042,576 1,061,667 1,062,233 1,056,107 1,033,518 1,023,726 1,019,351 1,013,115 50,251 104,677 2012 1,065,437 1,071,290 1,020,655 998,028 973,089 973,644 973,411 66,071 103,949 2013 1,044,142 1,062,045 1,047,230 1,021,007 1,002,316 987,763 86,250 91,084 2014 1,107,513 1,133,798 1,146,990 1,124,014 1,104,218 117,760 94,774 2015 1,114,081 1,130,513 1,144,830 1,138,313 175,271 93,673 2016 1,188,608 1,203,634 1,227,142 319,825 93,724 2017 1,270,110 1,313,372 471,978 96,426 2018 1,413,800 677,444 96,408 Total 10,921,712 All Lines (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 277,275 442,417 540,982 634,902 695,249 736,100 760,589 775,885 784,713 791,281 2010 328,826 509,910 625,229 704,895 773,536 803,773 823,770 835,532 846,386 2011 391,944 585,867 692,730 782,655 852,202 901,801 924,111 940,626 2012 378,067 555,819 651,544 743,742 810,135 856,195 879,372 2013 335,956 518,872 644,475 748,758 833,823 872,331 2014 405,898 614,075 736,154 855,959 936,425 2015 376,641 581,203 725,385 845,868 2016 387,272 617,958 764,331 2017 433,440 678,453 2018 511,271 Total 8,066,344 All outstanding liabilities before 2009, net of reinsurance 361,631 Liabilities for loss and loss expenses, net of reinsurance 3,216,999 General Liability (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 237,913 241,625 233,530 223,146 212,947 211,243 206,387 205,741 201,568 203,176 15,951 13,873 2010 215,208 228,680 242,499 237,154 222,328 211,619 208,968 202,394 206,146 18,634 12,696 2011 227,769 228,720 239,480 230,785 217,256 211,196 212,011 211,500 20,973 11,614 2012 238,979 245,561 215,083 194,144 175,305 175,268 180,659 25,251 9,960 2013 250,609 251,421 239,776 225,709 210,785 203,831 35,971 10,326 2014 244,312 249,946 257,132 239,333 234,082 57,041 10,513 2015 254,720 245,710 246,990 233,249 84,861 10,253 2016 277,214 272,048 277,986 142,991 10,213 2017 293,747 293,128 202,925 10,032 2018 317,934 270,267 8,741 Total 2,361,691 General Liability (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 14,346 37,143 64,970 103,213 130,554 151,920 166,767 176,316 180,621 183,263 2010 15,726 46,201 80,018 113,050 143,360 161,487 172,394 178,179 183,988 2011 13,924 42,692 73,643 102,978 135,377 159,768 170,525 181,856 2012 13,030 35,241 56,580 89,008 109,448 130,866 144,451 2013 12,789 35,113 72,127 104,587 139,114 153,628 2014 14,901 46,825 79,972 121,969 154,957 2015 14,665 39,978 78,668 116,804 2016 15,684 46,549 89,431 2017 17,366 49,470 2018 19,531 Total 1,277,379 All outstanding liabilities before 2009, net of reinsurance 90,918 Liabilities for loss and loss expenses, net of reinsurance 1,175,230 Workers Compensation (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 197,504 215,946 213,036 210,109 210,756 216,992 212,536 208,611 208,142 205,125 18,242 12,218 2010 198,371 214,469 212,815 211,030 214,916 212,448 208,155 204,423 199,539 22,614 12,185 2011 205,238 218,973 214,743 215,114 210,591 205,708 200,674 194,821 26,226 11,850 2012 203,864 208,036 199,360 195,197 188,596 187,359 183,314 30,444 11,613 2013 199,794 194,318 187,658 173,160 166,662 162,787 30,648 11,372 2014 199,346 187,065 182,579 172,515 164,420 33,422 10,488 2015 193,729 194,639 183,604 179,642 34,940 10,544 2016 196,774 184,946 176,248 56,258 10,553 2017 195,202 184,306 72,213 10,745 2018 193,894 98,015 10,553 Total 1,844,096 Workers Compensation (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 37,885 87,299 117,019 133,116 145,417 154,726 160,529 164,336 167,894 171,205 2010 46,795 93,281 122,442 137,184 149,086 153,795 158,078 162,796 165,526 2011 42,941 90,836 118,847 134,646 139,232 149,269 154,320 158,535 2012 40,911 86,909 108,211 122,755 132,052 139,477 143,281 2013 36,829 74,568 96,376 109,739 118,669 124,130 2014 35,924 78,944 100,876 113,626 119,392 2015 33,857 77,320 98,195 112,601 2016 34,525 78,531 98,037 2017 40,375 82,216 2018 41,122 Total 1,216,045 All outstanding liabilities before 2009, net of reinsurance 245,831 Liabilities for loss and loss expenses, net of reinsurance 873,882 Commercial Automobile (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 199,541 191,079 182,724 169,858 166,682 162,911 161,251 161,923 161,300 161,057 574 24,749 2010 187,562 189,305 187,778 181,923 179,854 172,969 173,157 173,471 173,080 762 25,406 2011 174,006 183,044 182,325 178,421 172,617 174,882 174,514 173,507 1,633 25,398 2012 179,551 191,947 183,527 184,289 184,367 186,128 184,633 2,259 24,025 2013 188,289 205,282 209,197 207,994 210,410 207,975 3,756 25,556 2014 200,534 212,725 216,824 219,925 218,172 8,718 27,528 2015 220,994 240,958 253,074 259,495 19,192 29,092 2016 255,187 274,367 285,302 46,407 30,855 2017 301,274 329,389 98,125 32,122 2018 347,908 164,906 32,895 Total 2,340,518 Commercial Automobile (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 63,126 94,406 113,697 137,564 149,949 155,560 158,303 159,723 160,013 160,456 2010 68,098 99,254 128,015 146,913 163,513 167,227 169,100 169,793 171,693 2011 69,849 99,196 121,576 142,507 157,291 166,082 170,000 170,913 2012 73,316 105,371 127,235 148,669 168,114 176,656 179,501 2013 76,469 109,893 140,015 169,850 189,626 200,750 2014 80,810 117,169 148,884 180,701 202,821 2015 91,347 132,260 175,866 211,515 2016 106,022 155,720 200,701 2017 117,287 178,823 2018 134,867 Total 1,812,040 All outstanding liabilities before 2009, net of reinsurance 3,842 Liabilities for loss and loss expenses, net of reinsurance 532,320 Businessowners' Policies (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 48,535 51,762 46,645 43,828 43,553 44,938 44,299 44,273 43,933 44,028 323 3,474 2010 53,669 49,285 42,408 39,915 40,899 40,581 41,239 41,197 40,920 381 3,918 2011 54,469 57,083 51,047 58,242 59,256 58,966 58,456 58,735 1,140 4,959 2012 54,342 48,029 46,303 44,172 44,077 43,747 43,418 430 5,542 2013 49,617 42,618 41,005 40,624 41,369 39,709 1,404 3,482 2014 55,962 60,949 62,548 59,806 58,517 2,959 4,062 2015 52,871 53,768 57,245 55,925 6,215 3,952 2016 52,335 53,792 54,993 9,272 3,823 2017 46,624 48,698 13,087 3,808 2018 55,024 16,177 3,823 Total 499,967 Businessowners' Policies (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 18,915 29,612 32,689 36,073 40,052 42,895 43,358 43,448 43,547 43,596 2010 20,821 28,131 31,027 34,705 37,819 38,900 40,279 40,395 40,439 2011 27,884 37,362 41,011 46,444 52,114 55,856 57,045 57,365 2012 22,199 31,833 35,089 37,215 38,766 40,627 41,326 2013 17,412 26,592 30,845 34,760 37,993 38,464 2014 28,914 40,584 44,911 49,460 52,940 2015 24,189 36,014 42,710 46,571 2016 24,655 36,848 39,973 2017 21,865 31,337 2018 29,995 Total 422,006 All outstanding liabilities before 2009, net of reinsurance 7,783 Liabilities for loss and loss expenses, net of reinsurance 85,744 Commercial Property (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 82,619 82,124 82,025 82,014 80,774 80,455 80,558 80,545 80,416 80,410 2 7,009 2010 105,647 96,851 97,386 96,127 95,530 95,363 95,178 95,155 95,142 4 7,668 2011 136,954 131,667 130,942 131,282 131,353 131,113 131,049 131,009 6 9,038 2012 118,464 114,224 115,375 116,658 117,102 117,170 117,225 21 8,515 2013 88,101 90,639 90,103 90,005 90,436 90,278 28 5,713 2014 141,192 136,249 136,820 138,751 138,155 57 6,514 2015 110,270 109,513 111,750 111,566 77 6,401 2016 121,927 126,185 125,937 405 6,727 2017 138,773 149,106 (76 ) 6,850 2018 183,177 7,052 7,695 Total 1,222,005 Commercial Property (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 59,933 78,695 80,433 80,894 80,251 80,352 80,529 80,509 80,405 80,393 2010 69,543 91,918 94,602 95,111 95,270 95,147 95,156 95,150 95,138 2011 94,538 127,580 129,579 130,681 131,060 131,115 131,089 131,100 2012 81,528 108,834 111,503 114,699 116,291 116,625 116,671 2013 60,244 87,874 90,446 90,350 90,840 90,696 2014 101,131 132,909 136,634 137,883 137,418 2015 79,048 106,182 109,829 110,994 2016 83,966 118,789 122,930 2017 99,047 142,338 2018 135,416 Total 1,163,094 All outstanding liabilities before 2009, net of reinsurance 69 Liabilities for loss and loss expenses, net of reinsurance 58,980 Personal Automobile (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 93,808 103,319 105,033 103,908 104,734 103,866 103,393 103,412 103,348 103,303 146 17,346 2010 103,340 110,075 112,346 109,515 107,490 107,405 107,224 107,054 106,887 160 20,822 2011 113,232 116,164 113,686 112,993 114,241 113,830 113,988 113,921 194 22,700 2012 113,771 114,921 109,832 109,324 110,294 110,300 109,795 205 22,332 2013 108,417 109,620 106,225 106,703 107,759 107,680 288 22,373 2014 102,250 109,325 106,757 107,452 106,821 774 22,504 2015 96,387 99,698 100,214 99,570 2,572 20,860 2016 92,727 98,032 100,202 6,252 19,803 2017 101,880 105,139 13,162 20,679 2018 111,594 23,506 21,748 Total 1,064,912 Personal Automobile (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 51,039 71,911 86,431 96,229 100,566 102,187 102,322 102,437 103,009 103,010 2010 58,786 82,490 95,300 101,540 104,061 105,849 106,453 106,733 106,722 2011 61,323 82,102 93,878 105,068 111,085 112,732 113,551 113,664 2012 63,704 82,729 94,842 102,977 107,890 109,355 109,447 2013 61,384 80,861 92,637 100,528 105,131 106,679 2014 62,519 83,739 92,589 99,173 104,055 2015 58,725 76,470 87,163 92,102 2016 57,961 76,823 86,752 2017 62,854 82,730 2018 69,721 Total 974,882 All outstanding liabilities before 2009, net of reinsurance 6,040 Liabilities for loss and loss expenses, net of reinsurance 96,070 Homeowners (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 47,636 44,511 42,609 40,313 61,927 40,400 40,465 40,457 40,451 40,500 70 5,634 2010 68,373 67,525 63,285 97,761 62,462 62,402 62,339 62,392 62,402 83 9,132 2011 103,804 98,211 82,744 94,167 94,543 94,183 94,378 94,587 131 15,109 2012 87,260 82,745 86,560 86,667 86,271 86,330 86,483 237 16,939 2013 73,670 72,528 71,494 72,145 71,714 72,148 331 7,747 2014 80,111 82,461 83,637 83,844 83,539 411 8,770 2015 76,637 76,400 76,559 74,723 1,172 7,744 2016 60,105 60,931 62,391 1,837 6,869 2017 59,167 67,978 1,969 7,299 2018 62,961 6,660 7,062 Total 707,712 Homeowners (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 28,299 36,965 38,078 39,342 39,731 39,819 39,907 40,189 40,269 40,403 2010 43,699 58,638 60,295 61,106 62,155 62,227 62,241 62,272 62,283 2011 71,668 89,963 91,718 92,185 93,312 93,720 94,007 94,412 2012 69,056 79,584 82,720 84,250 85,196 85,562 85,642 2013 50,664 65,528 67,838 69,775 71,776 72,197 2014 61,561 76,007 79,751 81,664 82,583 2015 52,589 70,078 72,202 72,927 2016 42,252 57,333 59,546 2017 45,466 63,290 2018 49,430 Total 682,713 All outstanding liabilities before 2009, net of reinsurance 6,107 Liabilities for loss and loss expenses, net of reinsurance 31,106 E&S Casualty Lines (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 885 1,053 938 728 710 96 737 739 — 274 2010 3,294 4,106 3,369 4,299 3,831 3,055 4,932 5,168 — 813 2011 8,127 7,102 9,853 12,207 10,273 9,652 10,228 12,119 276 1,321 2012 42,367 42,621 43,175 46,149 46,165 45,988 46,444 6,417 2,022 2013 55,468 60,309 67,099 69,112 67,647 68,972 14,175 2,266 2014 55,316 63,505 69,929 71,719 71,206 14,097 2,040 2015 75,498 76,432 82,404 90,488 24,516 2,746 2016 94,451 96,416 104,655 52,151 2,732 2017 91,438 95,783 66,321 2,353 2018 98,324 82,486 1,734 Total 593,898 E&S Casualty Lines (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ — 198 431 605 626 709 737 739 2010 — 1,218 2,570 3,574 4,078 4,513 4,610 4,908 2011 — 806 3,200 6,445 9,954 9,912 10,256 9,819 2012 3,722 7,914 16,430 25,064 32,343 36,278 38,298 2013 2,715 9,470 21,980 35,200 46,108 51,142 2014 2,353 12,234 25,571 43,877 53,780 2015 3,036 13,057 29,389 50,712 2016 3,720 16,195 33,950 2017 5,057 14,672 2018 5,509 Total 263,529 All outstanding liabilities before 2009, net of reinsurance 98 Liabilities for loss and loss expenses, net of reinsurance 330,467 In 2011, the Parent purchased Mesa Underwriters Specialty Insurance Company ("MUSIC"), a wholly-owned E&S Lines subsidiary of Montpelier Re Holdings, Ltd. Under the terms of the purchase agreement, the Parent acquired net loss and loss reserves amounting to approximately $15 million . All development on this acquired business was fully reinsured as of the acquisition date. (d) The reconciliation of the net incurred and paid claims development tables to the liability for loss and loss expenses in the consolidated statement of financial position is as follows: (in thousands) December 31, 2018 Net outstanding liabilities: Standard Commercial Lines General liability $ 1,175,230 Workers compensation 873,882 Commercial automobile 532,320 Businessowners' policies 85,744 Commercial property 58,980 Other Standard Commercial Lines 9,122 Total Standard Commercial Lines net outstanding liabilities 2,735,278 Standard Personal Lines Personal automobile 96,070 Homeowners 31,106 Other Standard Personal Lines 10,474 Total Standard Personal Lines net outstanding liabilities 137,650 E&S Lines Casualty lines 330,467 Property lines 13,604 Total E&S Lines net outstanding liabilities 344,071 Total liabilities for unpaid loss and loss expenses, net of reinsurance 3,216,999 Reinsurance recoverable on unpaid claims: Standard Commercial Lines General liability 181,102 Workers compensation 220,683 Commercial automobile 15,641 Businessowners' policies 3,473 Commercial property 12,620 Other Standard Commercial Lines 2,909 Total Standard Commercial Lines reinsurance recoverable on unpaid loss 436,428 Standard Personal Lines Personal automobile 45,572 Homeowners 1,346 Other Standard Personal Lines 31,777 Total Standard Personal Lines reinsurance recoverable on unpaid loss 78,695 E&S Lines Casualty lines 21,898 Property lines 367 Total E&S Lines reinsurance recoverable on unpaid loss 22,265 Total reinsurance recoverable on unpaid loss 537,388 Unallocated loss expenses 139,481 Total gross liability for unpaid loss and loss expenses $ 3,893,868 (e) The table below reflects the historical average annual percentage payout of incurred claims by age. For example, the general liability line of business averages payout of 6.5% of its ultimate losses in the first year, 12.2% in the second year, and so forth. The following is supplementary information about average historical claims duration as of December 31, 2018 : Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 General liability 6.5% 12.2 15.3 17.0 14.5 9.8 6.3 4.8 2.7 1.1 Workers compensation 21.2 24.3 13.2 8.3 5.4 3.9 2.4 2.3 1.4 1.1 Commercial automobile 37.9 17.3 14.5 13.1 9.5 4.0 1.6 0.8 0.7 0.4 Businessowners’ policies 47.3 19.9 8.3 8.3 7.4 4.3 1.7 0.5 0.2 1.1 Commercial property 70.7 25.2 2.7 1.1 0.2 0.1 — — — — Personal automobile 57.1 18.5 10.5 7.2 4.3 1.5 0.4 0.1 0.2 — Homeowners 72.3 20.3 3.1 1.8 1.4 0.4 0.2 0.1 0.1 0.1 E&S Lines - casualty 5.0 11.4 17.1 21.4 15.4 8.6 5.4

Indebtedness

Indebtedness	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Indebtedness	Indebtedness The table below provides a summary of our outstanding debt at December 31, 2018 and 2017 : Outstanding Debt 1 2018 Carry Value ($ in thousands) Issuance Date Maturity Date Interest Rate Original Amount Debt Discount and Unamortized Issuance Costs December 31, 2018 December 31, 2017 Description Long-term: (1) FHLBI 12/16/2016 12/16/2026 3.03 % $ 60,000 — 60,000 60,000 (2) FHLBNY 8/15/2016 8/16/2021 1.56 % 25,000 — 25,000 25,000 (2) FHLBNY 7/21/2016 7/21/2021 1.61 % 25,000 — 25,000 25,000 (3) Senior Notes 2/8/2013 2/9/2043 5.875 % 185,000 (4,229 ) 180,771 180,430 (4) Senior Notes 11/3/2005 11/1/2035 6.70 % 100,000 (931 ) 99,069 99,011 (5) Senior Notes 11/16/2004 11/15/2034 7.25 % 50,000 (300 ) 49,700 49,675 Total long-term debt $ 445,000 (5,460 ) 439,540 439,116 1 Beginning on January 1, 2019, finance lease obligations will also be included in our outstanding debt balance upon the adoption of the new lease accounting standard. For further information, refer to Note 3. "Adoption of Accounting Pronouncements, above. Short-term Debt SICA borrowed: (i) $75 million in short-term funds from the FHLBNY on February 27, 2018 at an interest rate of 1.75% , which was repaid on March 20, 2018 ; and (ii) $55 million in short-term funds from the FHLBNY on March 28, 2018 at an interest rate of 1.98% , which was repaid on April 18, 2018 . The Parent's line of credit with Wells Fargo Bank, National Association, as administrative agent, and Branch Banking and Trust Company (BB&T) (referred to as our "Line of Credit"), was renewed effective December 1, 2015 , with a borrowing capacity of $30 million , which can be increased to $50 million with the approval of both lending partners. Our Line of Credit expires on December 1, 2020, and has an interest rate, which varies and is based on, among other factors, the Parent’s debt ratings. There were no balances outstanding under our Line of Credit at December 31, 2018 or at any time during 2018 . Our Line of Credit agreement contains representations, warranties, and covenants that are customary for credit facilities of this type, including, without limitation, financial covenants under which we are obligated to maintain a minimum consolidated net worth, minimum combined statutory surplus, maximum ratio of consolidated debt to total capitalization, and covenants limiting our ability to: (i) merge or liquidate; (ii) incur debt or liens; (iii) dispose of assets; (iv) make investments and acquisitions; and (v) engage in transactions with affiliates. The table below outlines information regarding certain of the covenants in the Line of Credit: Required as of Actual as of December 31, 2018 December 31, 2018 Consolidated net worth Not less than $1.3 billion $1.8 billion Statutory surplus Not less than $750 million $1.8 billion Debt-to-capitalization ratio 1 Not to exceed 35% 19.7% A.M. Best financial strength rating Minimum of A- A 1 Calculated in accordance with the Line of Credit agreement. In addition to the above requirements, the Line of Credit agreement contains a cross-default provision that provides that the Line of Credit will be in default if we fail to comply with any condition, covenant, or agreement (including payment of principal and interest when due on any debt with an aggregate principal amount of at least $20 million ), which causes or permits the acceleration of principal. Additionally, the Line of Credit limits borrowings from the FHLBI and the FHLBNY to 10% of the respective member company's admitted assets for the previous year. Long-term Debt (1) In the first quarter of 2009, Selective Insurance Company of South Carolina ("SICSC") and Selective Insurance Company of the Southeast ("SICSE"), which are collectively referred to as the "Indiana Subsidiaries" as they are domiciled in Indiana, joined, and invested in, the FHLBI, which provides them with access to additional liquidity. The Indiana Subsidiaries’ aggregate investment in the FHLBI was $2.8 million at December 31, 2018 and December 31, 2017 . Our investment provides us the ability to borrow approximately 20 times the total amount of the FHLBI common stock purchased with additional collateral, at comparatively low borrowing rates. The proceeds from the FHLBI borrowing on December 16, 2016 of $60 million were used to repay a $45 million borrowing from the FHLBI that was outstanding at the time, with the remaining $15 million used for general corporate purposes. All borrowings from the FHLBI require security. For information on investments that are pledged as collateral for these borrowings, see Note 5. "Investments" above. (2) In the fourth quarter of 2015, SICA and Selective Insurance Company of New York ("SICNY") joined, and invested in, the FHLBNY, which provides them with access to additional liquidity. The aggregate investment for both subsidiaries was $2.7 million at December 31, 2018 and $2.6 million at December 31, 2017 . Our investment provides us the ability to borrow approximately 20 times the total amount of the FHLBNY common stock purchased with additional collateral, at comparatively low borrowing rates. In 2016, SICA borrowed the following amounts from the FHLBNY: (i) $25 million in August 2016 at an interest rate of 1.56% , which is due on August 16, 2021; and (ii) $25 million from the FHLBNY at an interest rate of 1.61% , which is due on July 21, 2021. All borrowings from the FHLBNY require security. For information on investments that are pledged as collateral for these borrowings, see Note 5. "Investments" above. (3) In February 2013, we issued $185 million of 5.875% Senior Notes due 2043. The notes became callable by us on February 8, 2018, at a price equal to 100% of their principal outstanding amount, plus accrued and unpaid interest to, but excluding, the date of redemption. A portion of the proceeds from this debt issuance was used to fully redeem the $100 million aggregate principal amount of our 7.5% Junior Subordinated Notes due 2066 that were outstanding at the time. Of the remaining net proceeds, $57.1 million was used to make capital contributions to the Insurance Subsidiaries, while the balance was used for general corporate purposes. There are no financial debt covenants to which we are required to comply in regards to these Senior Notes. (4) In November 2005, we issued $100 million of 6.70% Senior Notes due 2035 . These notes were issued at a discount of $0.7 million resulting in an effective yield of 6.754% . Net proceeds of approximately $50 million were used to fund an irrevocable trust that subsequently funded certain payment obligations in respect of our outstanding debt. The remainder of the proceeds was used for general corporate purposes. The agreements covering these notes contain a standard default cross-acceleration provision that provides the 6.70% Senior Notes will enter a state of default upon the failure to pay principal when due or upon any event or condition that results in an acceleration of principal of any other debt instrument in excess of $10 million that we have outstanding concurrently with the 6.70% Senior Notes. There are no financial debt covenants to which we are required to comply in regards to these notes. (5) In November 2004, we issued $50 million of 7.25% Senior Notes due 2034 . These notes were issued at a discount of $0.1 million , resulting in an effective yield of 7.27% . We contributed $25 million of the bond proceeds to the Insurance Subsidiaries as capital. The remainder of the proceeds was used for general corporate purposes. The agreements covering these notes contain a standard default cross-acceleration provision that provides the 7.25% Senior Notes will enter a state of default upon the failure to pay principal when due or upon any event or condition that results in an acceleration of principal of any other debt instrument in excess of $10 million that we have outstanding concurrently with the 7.25% Senior Notes. There are no financial debt covenants to which we are required to comply in regards to these notes.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information The disaggregated results of our four reportable segments are used by senior management to manage our operations. These reportable segments are evaluated as follows: • Our Standard Commercial Lines, Standard Personal Lines, and E&S Lines are evaluated based on before and after-tax underwriting results (net premiums earned, incurred loss and loss expense, policyholders dividends, policy acquisition costs, and other underwriting expenses), return on equity ("ROE") contribution, and combined ratios. • Our Investments segment is evaluated based on after-tax net investment income and its ROE contribution, as well as after-tax net realized and unrealized gains and losses. In computing the results of each segment, we do not make adjustments for interest expense or corporate expenses. We do not maintain separate investment portfolios for the segments and therefore, do not allocate assets to the segments. Our combined insurance operations are subject to certain geographic concentrations, particularly in the Northeast and Mid-Atlantic regions of the country. In 2018 , approximately 19% of NPW were related to insurance policies written in New Jersey. We had a goodwill balance of $7.8 million at both December 31, 2018 and 2017 on our Consolidated Balance Sheet that relates to our Standard Commercial Lines reporting unit. The following summaries present revenues (net investment income and net realized gains on investments in the case of the Investments segment) and pre-tax income for the individual segments: Revenue by Segment Years ended December 31, ($ in thousands) 2018 2017 2016 Standard Commercial Lines: Net premiums earned: Commercial automobile $ 493,093 442,818 398,942 Workers compensation 317,616 317,982 308,233 General liability 616,187 569,217 527,859 Commercial property 329,660 311,932 293,438 Businessowners’ policies 103,412 100,266 97,754 Bonds 33,991 29,086 23,227 Other 18,263 17,198 16,030 Miscellaneous income 8,180 9,488 7,782 Total Standard Commercial Lines revenue 1,920,402 1,797,987 1,673,265 Standard Personal Lines: Net premiums earned: Personal automobile 168,250 153,147 142,876 Homeowners 128,961 129,699 130,973 Other 7,230 6,855 6,758 Miscellaneous income 1,257 1,228 1,098 Total Standard Personal Lines revenue 305,698 290,929 281,705 E&S Lines: Net premiums earned: Casualty lines 164,313 157,366 151,638 Property lines 55,253 55,461 51,844 Miscellaneous income 1 — 1 Total E&S Lines revenue 219,567 212,827 203,483 Investments: Net investment income 195,336 161,882 130,754 Net realized and unrealized investment (losses) gains (54,923 ) 6,359 (4,937 ) Total Investments revenues 140,413 168,241 125,817 Total revenues $ 2,586,080 2,469,984 2,284,270 Income Before and After Federal Income Tax Years ended December 31, ($ in thousands) 2018 2017 2016 Standard Commercial Lines: Underwriting gain, before federal income tax $ 109,104 149,514 146,435 Underwriting gain, after federal income tax 86,192 97,184 95,183 Combined ratio 94.3 % 91.6 % 91.2 % ROE contribution 4.9 % 6.1 6.4 Standard Personal Lines: Underwriting gain, before federal income tax 12,764 11,104 12,419 Underwriting gain, after federal income tax 10,084 7,217 8,072 Combined ratio 95.8 % 96.2 % 95.6 % ROE contribution 0.6 % 0.4 0.6 E&S Lines: Underwriting loss, before federal income tax (695 ) (6,282 ) (6,921 ) Underwriting loss, after federal income tax (549 ) (4,083 ) (4,499 ) Combined ratio 100.3 % 103.0 % 103.4 % ROE contribution — % (0.3 ) (0.3 ) Investments: Net investment income $ 195,336 161,882 130,754 Net realized and unrealized investment (losses) gains (54,923 ) 6,359 (4,937 ) Total investment income, before federal income tax 140,413 168,241 125,817 Tax on investment income 19,560 45,588 30,621 Total investment income, after federal income tax $ 120,853 122,653 95,196 ROE contribution of after-tax net investment income 6.9 % 7.5 6.5 Reconciliation of Segment Results to Income Before Federal Income Tax Years ended December 31, ($ in thousands) 2018 2017 2016 Underwriting gain (loss) Standard Commercial Lines $ 109,104 149,514 146,435 Standard Personal Lines 12,764 11,104 12,419 E&S Lines (695 ) (6,282 ) (6,921 ) Investment income 140,413 168,241 125,817 Total all segments 261,586 322,577 277,750 Interest expense (24,419 ) (24,354 ) (22,771 ) Corporate expenses (25,446 ) (36,255 ) (35,024 ) Income, before federal income tax $ 211,721 261,968 219,955

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Earnings per Share The following table provides a reconciliation of the numerators and denominators of basic and diluted earnings per share ("EPS"): 2018 Income Shares Per Share ($ in thousands, except per share amounts) (Numerator) (Denominator) Amount Basic EPS: Net income available to common stockholders $ 178,939 58,950 $ 3.04 Effect of dilutive securities: Stock compensation plans — 763 Diluted EPS: Net income available to common stockholders $ 178,939 59,713 $ 3.00 2017 Income Shares Per Share ($ in thousands, except per share amounts) (Numerator) (Denominator) Amount Basic EPS: Net income available to common stockholders $ 168,826 58,458 $ 2.89 Effect of dilutive securities: Stock compensation plans — 899 Diluted EPS: Net income available to common stockholders $ 168,826 59,357 $ 2.84 2016 Income Shares Per Share ($ in thousands, except per share amounts) (Numerator) (Denominator) Amount Basic EPS: Net income available to common stockholders $ 158,495 57,889 $ 2.74 Effect of dilutive securities: Stock compensation plans — 858 Diluted EPS: Net income available to common stockholders $ 158,495 58,747 $ 2.70

Federal Income Taxes

Federal Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal Income Taxes	Federal Income Taxes (a) On December 22, 2017, the Tax Cuts and Jobs Act of 2017 ("Tax Reform") was signed into law, which among other implications, reduced our statutory corporate tax rate from 35% to 21% beginning with our 2018 tax year. We revalued our deferred tax inventory at December 31, 2017 to reflect this reduction, which resulted in a $20.2 million charge to income as illustrated in the rate table below. As of December 31, 2017, our accounting for the impact of Tax Reform on our deferred tax assets and liabilities was complete with the exception of amounts related to loss reserve discounting. Prior to Tax Reform, we had elected to use our own loss reserve payment patterns for determining the factors to be used for calculating our discounted loss reserves for federal income tax purposes. Under Tax Reform, this election was eliminated and we are now required to utilize discount factors based on industry experience and a corporate bond yield curve, which the IRS had not finalized as of December 31, 2017. Considering this, at December 31, 2017, we calculated a pre-tax decrease to our discounted loss reserves of $35 million by utilizing the industry experience approach under the tax law that existed prior to Tax Reform. This increased the deferred tax asset related to loss reserves by $7.5 million . A Tax Reform transition rule allows this change in accounting method to be amortized into expense over an eight-year period beginning in 2018. As a result, we established an offsetting deferred tax liability of $7.5 million as of December 31, 2017. In the fourth quarter of 2018, the IRS published the loss reserve discount factors to be used for calculating the beginning and ending 2018 discounted loss reserves under the industry experience approach. Based on these factors, we calculated a pre-tax decrease to our discounted loss reserves of $125 million , which resulted in a deferred tax asset of $26.3 million , an increase from the $7.5 million estimate described above. The $26.3 million adjustment is being taken into income over eight years, beginning with 2018, at approximately $3.3 million per year. (b) A reconciliation of federal income tax on income at the corporate rate to the effective tax rate is as follows: ($ in thousands) 2018 2017 2016 Tax at statutory rate (21% in 2018 and 35% in 2017 and 2016) $ 44,461 91,689 76,984 Tax-advantaged interest (5,518 ) (11,510 ) (12,126 ) Dividends received deduction (647 ) (1,961 ) (1,114 ) Executive compensation 2,279 — 121 Stock-based compensation (3,093 ) (4,281 ) — Tax Reform deferred tax write off — 20,205 — Other 1 (4,700 ) (1,000 ) (2,405 ) Federal income tax expense from continuing operations $ 32,782 93,142 61,460 1 2018 includes approximately $3.8 million of capital loss carry back items to prior tax years at the previous 35% statutory tax rate. In addition to the impact of Tax Reform discussed above, our statutory tax rate reconciliation for 2018 and 2017 benefited from accounting literature implemented in 2017 that requires the tax effects of share-based compensation to be recognized in the income tax provision. Prior to 2017, these amounts were recorded in additional paid-in capital. (c) The tax effects of the significant temporary differences that gave rise to deferred tax assets and liabilities were as follows: ($ in thousands) 2018 2017 Deferred tax assets: Net loss reserve discounting $ 43,285 38,771 Net unearned premiums 53,556 50,267 Employee benefits 8,862 8,606 Long-term incentive compensation plans 9,095 12,221 Temporary investment write-downs 1,155 1,044 Net operating loss — 54 Other 5,744 5,784 Total deferred tax assets 121,697 116,747 Deferred tax liabilities: Deferred policy acquisition costs 53,049 47,484 Unrealized gains on investment securities 502 26,183 Other investment-related items, net 4,904 2,500 Accelerated depreciation and amortization 9,702 8,590 Total deferred tax liabilities 68,157 84,757 Net deferred federal income tax asset $ 53,540 31,990 Net deferred income tax assets increased by $21.6 million in 2018, driven by an $18.6 million decrease in gross deferred tax liabilities as rising interest rates have reduced unrealized gains on our fixed income securities portfolio. After considering all evidence, both positive and negative, with respect to our federal tax loss carryback availability, expected levels of pre-tax financial statement income, and federal taxable income, we believe it is more likely than not that the existing deductible temporary differences will reverse during periods in which we generate net federal taxable income or have adequate federal carryback availability. As a result, we had no valuation allowance recognized for federal deferred tax assets at December 31, 2018 or 2017 . We have analyzed our tax positions in all open tax years, which as of December 31, 2018 were 2015 through 2017 , and we believe our tax positions will more likely than not be sustained upon examination, including related appeals or litigation. In the event we had a tax position that did not meet the more likely than not criteria, any tax, interest, and penalties incurred related to such a position would be reflected in "Total federal income tax expense" on our Consolidated Statements of Income. We are not currently under a federal income tax audit for any tax year.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Retirement Plans	Retirement Plans (a) Selective Insurance Retirement Savings Plan (“Retirement Savings Plan”) SICA offers a voluntary defined contribution 401(k) plan that is available to most of our employees and is a tax-qualified retirement plan subject to ERISA. Expense recorded for this plan was $15.8 million in both 2018 and 2017 , and $15.0 million in 2016 . (b) Deferred Compensation Plan SICA offers a non-qualified deferred compensation plan, the Selective Insurance Company of America Deferred Compensation Plan ("Deferred Compensation Plan") to a group of management or highly compensated employees as a method of recognizing and retaining such employees. The Deferred Compensation Plan provides these employees the opportunity to elect to defer receipt of specified portions of compensation and to have such deferred amounts deemed to be invested in specified investment options. In addition to the employee deferrals, SICA may choose to make matching contributions to some or all of the participants in this plan to the extent the participant did not receive the maximum matching or non-elective contributions permissible under the Retirement Savings Plan due to limitations under the Internal Revenue Code or the Retirement Savings Plan. Expense recorded for these contributions was $0.4 million in 2018 , $0.2 million in 2017 , and $0.3 million in 2016 . (c) Retirement Income Plan and Retirement Life Plan SICA maintains a defined benefit pension plan, the Retirement Income Plan for Selective Insurance Company of America (the "Pension Plan"). This qualified, noncontributory plan is closed to new entrants and existing participants ceased accruing benefits after March 31, 2016 . In addition to the Pension Plan, SICA also sponsors the Supplemental Excess Retirement Plan (the "Excess Plan") and a life insurance benefit plan (the "Retirement Life Plan"). Both of these plans are closed to new entrants and participants in the Excess Plan ceased accruing benefits after March 31, 2016 . The Retirement Life Plan does not accrue benefits and this plan applies only to retirees who terminated employment with SICA on or before March 31, 2009. These are both unfunded plans with benefit obligations as of December 31, 2018 and December 31, 2017 of $9.5 million and $10.1 million , respectively, for the Excess Plan and $5.8 million and $6.4 million , respectively, for the Retirement Life Plan. Expense recorded for the Excess Plan was $0.4 million in both 2018 and 2017 , and $0.5 million in 2016 . Expense recorded for the Retirement Life Plan was $0.3 million in each of 2018 , 2017 , and 2016 . The following tables provide details on the Pension Plan for 2018 and 2017 : December 31, Pension Plan ($ in thousands) 2018 2017 Change in Benefit Obligation: Benefit obligation, beginning of year $ 364,411 330,588 Service cost — — Interest cost 12,428 12,490 Actuarial (gains) losses (31,738 ) 31,158 Benefits paid (10,422 ) (9,825 ) Benefit obligation, end of year $ 334,679 364,411 Change in Fair Value of Assets: Fair value of assets, beginning of year $ 363,673 316,515 Actual return on plan assets, net of expenses (21,571 ) 46,983 Contributions by the employer to funded plans — 10,000 Benefits paid (10,422 ) (9,825 ) Fair value of assets, end of year $ 331,680 363,673 Funded status $ (2,999 ) (738 ) Amounts Recognized in the Consolidated Balance Sheet: Liabilities $ (2,999 ) (738 ) Net pension liability, end of year $ (2,999 ) (738 ) Amounts Recognized in AOCI: Net actuarial loss $ 98,057 87,438 Total $ 98,057 87,438 Other Information as of December 31: Accumulated benefit obligation $ 334,679 364,411 Weighted-Average Liability Assumptions as of December 31: Discount rate 4.46 % 3.78 Pension Plan ($ in thousands) 2018 2017 2016 Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Income: Net Periodic Benefit Cost: Service cost $ — — 1,647 Interest cost 12,428 12,490 12,336 Expected return on plan assets (22,767 ) (19,419 ) (17,309 ) Amortization of unrecognized actuarial loss 1,981 2,001 6,299 Total net periodic cost $ (8,358 ) (4,928 ) 2,973 Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Net actuarial loss (gain) $ 12,600 3,594 11,316 Reversal of amortization of net actuarial loss (1,981 ) (2,001 ) (6,299 ) Total recognized in other comprehensive income $ 10,619 1,593 5,017 Total recognized in net periodic benefit cost and other comprehensive income $ 2,261 (3,335 ) 7,990 The estimated net actuarial loss for the Pension Plan that will be amortized from AOCI into net periodic benefit cost during the 2019 fiscal year is $2.6 million . Pension Plan 2018 2017 2016 Weighted-Average Expense Assumptions for the years ended December 31: Discount rate 3.78 % 4.41 4.69 Expected return on plan assets 6.36 6.24 6.37 Rate of compensation increase 1 — — — 1 This assumption was 4.00% through March 31, 2016, the date after which benefits ceased accruing for all participants of the Pension Plan. Our latest measurement date was December 31, 2018 , at which time we increased our expected return on plan assets to 6.50% , reflecting a higher expected allocation to risk-seeking assets in the portfolio. When determining the most appropriate discount rate to be used in the valuation, we consider, among other factors, our expected payout patterns of the Pension Plan's obligations as well as our investment strategy, and we ultimately select the rate that we believe best represents our estimate of the inherent interest rate at which our pension and post-retirement life benefits can be effectively settled. The approach we utilize discounts the individual expected cash flows using the applicable spot rates derived from the yield curve over the projected cash flow period. The weighted average discount rate used to determine 2019 interest cost is 4.12% . Pension Plan Assets Assets of the Pension Plan are invested to adequately support the liability associated with the Pension Plan's defined benefit obligation. Our return objective is to exceed the returns of the plan's policy benchmark, which is the return the plan would have earned if the assets were invested according to the target asset class weightings and earned index returns shown below. In 2019, we will continue to phase in adjustments to the asset allocation to steadily close the gap between the duration of the assets and the duration of the liabilities, provided certain improved funding targets are achieved. Over time, the target and actual asset allocations may change based on the funded status of the Pension Plan and market return expectations. The Pension Plan’s target ranges, as well as the actual weighted average asset allocation by strategy, at December 31 were as follows: 2018 2017 Target Percentage 2 Actual Percentage Actual Percentage Return seeking assets 1 15%-70% 43 % 58 % Liability hedging assets 35%-75% 38 % 40 % Short-term investments 3 0%-2% 19 % 2 % Total 100 % 100 % 100 % 1 Includes limited partnerships. 2 Target percent allocations may change over time based on the funded status of the plan and market return expectations. 3 The actual percentage of assets allocated to short-term investments is higher than our target as of December 31, 2018 due to portfolio rebalancing initiatives that are expected to be completed during 2019. As part of this rebalancing initiative, $49 million , or 15% , of plan assets were redeployed into risk seeking assets in January 2019. Excluding the impact of this redeployment, our short-term investments represented 5% of plan assets at December 31, 2018. The use of derivative instruments is permitted under certain circumstances for the Pension Plan portfolio, but may not be used for unrelated speculative purposes or to create exposures that are not permitted in the Pension Plan's investment guidelines. Within the liability hedging assets, derivatives may be used to mitigate interest rate risk and reduce the interest duration mismatch between assets and liabilities of the Pension Plan to help insulate the funded status of the plan. We currently invest in a U.S. Treasury overlay derivative strategy, within the funds in our liability hedging assets, to manage the interest rate duration mismatch between the assets and liabilities of the Pension Plan. Considering the impact of this derivative overlay, the liability hedging assets provide for an approximate 50% hedge against the projected benefit obligation. The Pension Plan had no investments in the Parent’s common stock as of December 31, 2018 or 2017 . For information regarding investments in funds of our related parties, refer to Note 16. "Related Party Transactions" below. The techniques used to determine the fair value of the Pension Plan's invested assets that appear on the following page are as follows: • The investments in the global equity and liability hedging funds are collective investment funds that utilize a market approach wherein the published prices in the active market for identical assets are used. These investments are traded at their net asset value per share. There are no restrictions as to the redemption of these investments nor do we have any contractual obligations for further investment. These investments are classified as Level 1 in the fair value hierarchy. • The investments in private limited partnerships and other private equity securities are valued utilizing net asset value as a practical expedient for fair value. These investments are not classified in the fair value hierarchy. • Short-term investments are carried at cost, which approximates fair value. Given that these investments are listed on active exchanges, coupled with their liquid nature, these investments are classified as Level 1 in the fair value hierarchy. • The deposit administration contract is carried at cost, which approximates fair value. Given the liquid nature of the underlying investments in overnight cash deposits and other short-term duration products, we have determined that a correlation exists between the deposit administration contract and other short-term investments, such as money market funds. As such, this investment is classified as Level 2 in the fair value hierarchy. For discussion regarding the levels within the fair value hierarchy, see Note 2. "Summary of Significant Accounting Policies." In addition, refer to Note 5. "Investments" for discussion regarding the limited partnership investment strategies, excluding the middle market lending strategy, as these investments are not part of the Pension Plan. The Pension Plan invests in hedge funds, as part of its overall private asset strategy, with diversified exposure to a number of underlying systematic strategies that include arbitrage, macro-oriented, and equity-related strategies. These positions are expected to improve the risk-adjusted return of the portfolio given their lower volatility profile than public equities, with returns that are generally uncorrelated to traditional asset classes over a complete market cycle. The following tables provide quantitative disclosures of the Pension Plan’s invested assets that are measured at fair value on a recurring basis: December 31, 2018 Fair Value Measurements at 12/31/18 Using ($ in thousands) Assets Measured at Fair Value At 12/31/18 Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description Return seeking assets: Global equity $ 113,409 113,409 — — Private assets 1 : Limited partnerships (at net asset value): Real assets 16,818 — — — Private equity 878 — — — Private credit 262 — — — Hedge fund 7,889 — — — Total limited partnerships 25,847 — — — Other private assets 3,780 — — — Total private assets 29,627 — — — Total return seeking assets 143,036 113,409 — — Liability hedging assets: Fixed income 106,000 106,000 — — U.S. Treasury overlay 18,528 18,528 — — Total liability hedging assets 124,528 124,528 — — Cash and short-term investments: Short-term investments 62,788 62,788 — — Deposit administration contracts 1,482 — 1,482 — Total cash and short-term investments 64,270 62,788 1,482 — Total invested assets $ 331,834 300,725 1,482 — December 31, 2017 Fair Value Measurements at 12/31/17 Using ($ in thousands) Assets Measured at Fair Value At 12/31/17 Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description Return seeking assets: Long-duration fixed income: Global asset allocation fund $ 41,309 41,309 — — Global equity: Non-U.S. equity 67,989 67,989 — — U.S. equity 66,353 66,353 — — Total global equity 134,342 134,342 — — Private assets (limited partnerships, at net asset value) 1 : Real assets 16,305 — — — Private equity 1,096 — — — Private credit 460 — — — Hedge fund 15,192 — — — Total limited partnerships 33,053 — — — Other private assets 980 — — 980 Total private assets 34,033 — — 980 Total return seeking assets 209,684 175,651 — 980 Liability hedging assets: Long-duration fixed income: Extended duration fixed income 146,837 146,837 — — Total liability hedging assets 146,837 146,837 — — Cash and short-term investments: Short-term investments 4,939 4,939 — — Deposit administration contracts 1,615 — 1,615 — Total cash and short-term investments 6,554 4,939 1,615 — Total invested assets $ 363,075 327,427 1,615 980 1 In accordance with ASU 2015-07, certain investments that are measured at fair value using the net asset value per share (or its practical expedient) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to total Pension Plan invested assets. Contributions We presently do not anticipate contributing to the Pension Plan in 2019 , as we have no minimum required contribution amounts. Benefit Payments ($ in thousands) Pension Plan Benefits Expected to be Paid in Future Fiscal Years: 2019 $ 13,920 2020 13,869 2021 15,026 2022 16,159 2023 17,134 2024-2028 99,197

Share-Based Payments

Share-Based Payments	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	Share-Based Payments Active Plans As of December 31, 2018 , the following four plans were available for the issuance of share-based payment awards: • The 2014 Omnibus Stock Plan, As Amended and Restated Effective as of May 2, 2018 (the "Stock Plan"); • The Cash Incentive Plan, As Amended and Restated as of May 1, 2014 (the "Cash Plan"); • The Employee Stock Purchase Plan (2009) ("ESPP"); and • The Amended and Restated Stock Purchase Plan for Independent Insurance Agencies (2010), Amended and Restated as of February 1, 2017 (the "Agent Plan"). The following table provides information regarding the approval of these plans: Plan Approvals Stock Plan Approved effective as of May 1, 2014 by stockholders on April 23, 2014. Most recently amended and restated plan was approved effective May 2, 2018 by stockholders on May 2, 2018. Cash Plan Approved effective April 1, 2005 by stockholders on April 27, 2005. ESPP Approved by stockholders on April 29, 2009 effective July 1, 2009. Agent Plan Approved by stockholders on April 26, 2006. The types of awards that can be issued under each of these plans are as follows: Plan Types of Share-Based Payments Issued Stock Plan Qualified and nonqualified stock options, stock appreciation rights ("SARs"), restricted stock, restricted stock units ("RSUs"), stock grants, and other awards valued in whole or in part by reference to the Parent's common stock. The maximum exercise period for an option grant under this plan is 10 years from the date of the grant. Dividend equivalent units ("DEUs") are earned during the vesting period on RSU grants. The DEUs are reinvested in the Parent's common stock at fair value on each dividend payment date. The requisite service period for grants to employees under this plan is the lesser of: (i) the stated vested date, which is typically three years from issuance; or (ii) the date the employee becomes eligible to retire. Cash Plan Cash incentive units (“CIUs”). The initial dollar value of each CIU will be adjusted to reflect the percentage increase or decrease in the total shareholder return on the Parent's common stock over a specified performance period. In addition, for certain grants, the number of CIUs granted will be increased or decreased to reflect our performance on specified performance indicators as compared to targeted peer companies. The requisite service period for grants under this plan is the lesser of: (i) the stated vested date, which is typically three years from issuance; or (ii) the date the employee becomes eligible to retire. ESPP Enables employees to purchase shares of the Parent’s common stock. The purchase price is the lower of: (i) 85% of the closing market price at the time the option is granted; or (ii) 85% of the closing price at the time the option is exercised. Shares are generally issued on June 30 and December 31 of each year. Agent Plan Quarterly offerings to purchase the Parent's common stock at a 10% discount with a one year restricted period during which the shares purchased cannot be sold or transferred. Only our independent retail insurance agencies and wholesale general agencies, and certain eligible persons associated with the agencies, are eligible to participate in this plan. Shares authorized and available for issuance as of December 31, 2018 are as follows: As of December 31, 2018 Authorized Available for Issuance Awards Outstanding Stock Plan 4,750,000 3,461,192 864,478 ESPP 1,500,000 429,181 — Agent Plan 3,000,000 1,776,359 — Retired Plans The following plans are closed for the issuance of new awards, although awards outstanding continue in effect according to the terms of the applicable award agreements: December 31, 2018 Types of Share-Based Payments Issued Reserve Shares Awards Outstanding 1 Plan 2005 Omnibus Stock Plan ("2005 Stock Plan") Qualified and nonqualified stock options, SARs, restricted stock, RSUs, phantom stock, stock bonuses, and other awards in such amounts and with such terms and conditions as it determined, subject to the provisions of the 2005 Stock Plan. The maximum exercise period for an option grant under this plan is 10 years from the date of the grant. DEUs are earned during the vesting period on RSU grants. The DEUs are reinvested in the Parent's common stock at fair value on each dividend payment date. 2,099,403 174,003 Parent's Stock Compensation Plan for Non-employee Directors ("Directors Stock Compensation Plan") Directors could elect to receive a portion of their annual compensation in shares of the Parent's common stock. 65,770 65,770 1 Awards outstanding under the 2005 Stock Plan consisted of 47,268 shares deferred by our non-employee directors and 126,735 stock options. RSU Transactions A summary of the RSU transactions under our share-based payment plans is as follows: Number Weighted Unvested RSU awards at December 31, 2017 865,587 $ 33.66 Granted in 2018 303,550 55.96 Vested in 2018 (303,606 ) 26.57 Forfeited in 2018 (19,226 ) 42.62 Unvested RSU awards at December 31, 2018 846,305 $ 44.00 As of December 31, 2018 , total unrecognized compensation expense related to unvested RSU awards granted under our Stock Plan was $11.0 million . That expense is expected to be recognized over a weighted-average period of 1.7 years . The total intrinsic value of RSUs vested was $18.0 million for 2018 , $16.0 million for 2017 , and $12.6 million for 2016 . In connection with vested RSUs, the total value of the DEUs that vested was $0.8 million in 2018 , $0.9 million in 2017 , and $0.7 million in 2016 . Option Transactions A summary of the stock option transactions under our 2005 Stock Plan is as follows: Number Weighted Weighted Aggregate Outstanding at December 31, 2017 229,864 $ 15.38 Granted in 2018 — — Exercised in 2018 (103,129 ) 16.62 Forfeited or expired in 2018 — — Outstanding at December 31, 2018 126,735 $ 14.37 0.80 $ 5,903 Exercisable at December 31, 2018 126,735 $ 14.37 0.80 $ 5,903 The total intrinsic value of options exercised was $4.5 million in 2018 , $4.0 million in 2017 , and $2.3 million in 2016 . CIU Transactions The liability recorded in connection with our Cash Plan was $21.6 million at December 31, 2018 and $37.0 million at December 31, 2017 . The remaining cost associated with the CIUs is expected to be recognized over a weighted average period of 0.8 years . The CIU payments made were $20.2 million in 2018 , $14.2 million in 2017 , and $14.3 million in 2016 . ESPP and Agent Plan Transactions A summary of ESPP and Agent Plan share issuances is as follows: 2018 2017 2016 ESPP Issuances 70,448 75,093 88,432 Agent Plan Issuances 41,134 49,794 69,867 Fair Value Measurements The grant date fair value of RSUs is based on the market price of our common stock on the grant date, adjusted for the present value of our expected dividend payments. The expense recognized for share-based awards is based on the number of shares or units expected to be issued at the end of the performance period and the grant date fair value. The grant date fair value of each option award is estimated using the Black Scholes option valuation model ("Black Scholes"). The following are the significant assumptions used in applying Black Scholes: (i) the risk-free interest rate, which is the implied yield currently available on U.S. Treasury zero-coupon issues with an equal remaining term; (ii) the expected term, which is based on historical experience of similar awards; (iii) the dividend yield, which is determined by dividing the expected per share dividend during the coming year by the grant date stock price; and (iv) the expected volatility, which is based on the volatility of the Parent's stock price over a historical period comparable to the expected term. In applying Black Scholes, we use the weighted average assumptions illustrated in the following table: ESPP 2018 2017 2016 Risk-free interest rate 1.88 % 1.07 0.47 Expected term 6 months 6 months 6 months Dividend yield 1.3 % 1.3 1.7 Expected volatility 18 % 24 31 The weighted-average fair value of options and stock per share, including RSUs granted for the Parent's stock plans, during 2018 , 2017 , and 2016 was as follows: 2018 2017 2016 RSUs $ 55.96 42.66 32.53 ESPP: Six month option 2.67 2.73 2.63 Discount of grant date market value 8.50 7.06 5.23 Total ESPP 11.17 9.79 7.86 Agent Plan: Discount of grant date market value 5.99 5.04 3.79 The fair value of the CIU liability is remeasured at each reporting period through the settlement date of the awards, which is three years from the date of grant based on an amount expected to be paid. A Monte Carlo simulation is performed to approximate the projected fair value of the CIUs that, in accordance with the CIU agreements established under the Cash Plan, is adjusted to reflect our performance on specified indicators as compared to targeted peer companies. Expense Recognition The following table provides share-based compensation expense in 2018 , 2017 , and 2016 : ($ in millions) 2018 2017 2016 Share-based compensation expense, pre-tax $ 19.3 31.2 30.3 Income tax benefit, including the benefit related to stock grants that have vested during the year (7.0 ) (15.0 ) (10.3 ) Share-based compensation expense, after-tax $ 12.3 16.2 20.0

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions William M. Rue, a Director of the Parent, is Chairman of, and owns more than 10% of the equity of, Chas. E. Rue & Son, Inc., t/a Rue Insurance, a general independent retail insurance agency ("Rue Insurance"). Rue Insurance is an appointed distribution partner of the Insurance Subsidiaries on terms and conditions similar to those of our other distribution partners, which includes the right to participate in the Agent Plan. Mr. Rue’s son is President, and an employee, of Rue Insurance, and owns more than 10% of the equity of Rue Insurance. Mr. Rue’s daughter is an employee of Rue Insurance. Our relationship with Rue Insurance has existed since 1928. Rue Insurance placed insurance policies with the Insurance Subsidiaries for its customers and itself. Direct premiums written associated with these policies were $10.1 million in 2018 , $11.1 million in 2017 , and $10.4 million in 2016 . In return, the Insurance Subsidiaries paid standard market commissions, including supplemental commissions, to Rue Insurance of $2.1 million in 2018 , $2.3 million in 2017 , and $2.1 million in 2016 . Amounts due to Rue Insurance at December 31, 2018 and December 31, 2017 were $0.4 million and $0.6 million , respectively. All contracts and transactions with Rue Insurance were consummated in the ordinary course of business on an arm's-length basis. In 2005, we established a private foundation, now named The Selective Insurance Group Foundation (the "Foundation"), under Section 501(c)(3) of the Internal Revenue Code. The Board of Directors of the Foundation is comprised of some of the Parent's officers. We made $0.5 million of contributions to the Foundation in 2018 . We made no contributions to the Foundation in 2017 and 2016 , respectively. BlackRock, Inc., a leading publicly traded investment management firm (“BlackRock”), has purchased our common shares in the ordinary course of its investment business and has previously filed Schedules 13G/A with the SEC. On January 31, 2019, BlackRock filed a Schedule 13G/A reporting beneficial ownership as of December 31, 2018 , of 14.2% of our common stock. In connection with purchasing our common shares, BlackRock filed the necessary filings with insurance regulatory authorities. On the basis of those filings, BlackRock is deemed not to be a controlling person for the purposes of applicable insurance law. We are required to disclose related party information for our transactions with BlackRock. BlackRock is highly regulated, serves its clients as a fiduciary, and has a diverse platform of active (alpha) and index (beta) investment strategies across asset classes that enables it to tailor investment outcomes and asset allocation solutions for clients. BlackRock also offers the BlackRock Solutions ® investment and risk management technology platform, Aladdin ® , risk analytics, advisory, and technology services and solutions to a broad base of institutional and wealth management investors. We incurred expenses related to BlackRock for services rendered of $2.0 million in both 2018 and 2017 , and $0.4 million in 2016 . Amounts payable for such services at December 31, 2018 and December 31, 2017 , were $1.0 million and $0.5 million , respectively. As part of our overall investment diversification, we invest in various BlackRock funds from time to time. The market value of these investments were $0.8 million at December 31, 2018 , and $0.5 million at both December 31, 2017 and December 31, 2016 . There were no material transactions related to these holdings in 2018 and 2017 . During 2016 , we sold $77.6 million of these investments, which resulted in a $1.1 million gain on our investment portfolio. In addition, we recorded $2.3 million of investment income on these funds in 2016 . There were no amounts payable on the settlement of these investment transactions at December 31, 2018 or December 31, 2017 . Our Pension Plan contained investments in BlackRock funds of $131.9 million at December 31, 2018 and $134.3 million at December 31, 2017 . We recorded a net investment loss on these funds of $9.3 million in 2018, net investment income of $25.2 million in 2017, and net investment income of $8.5 million in 2016. In addition, our Deferred Compensation Plan and Retirement Savings Plan may offer our employees the option to invest in various BlackRock funds. All contracts and transactions with BlackRock were consummated in the ordinary course of business on an arm's-length basis. The Vanguard Group ("Vanguard"), one of the world's largest investment management companies, offers low cost mutual funds and exchange-trade funds ("ETFs"), as well as other investment related services. On January 10, 2019, Vanguard filed a Schedule 13G/A reporting beneficial ownership as of December 31, 2018 , of 10.1% of our common stock. In connection with purchasing our common shares, Vanguard filed the necessary filings with insurance regulatory authorities. On the basis of those filings, we do not expect Vanguard to be deemed a controlling person for the purposes of applicable insurance law. We are required to disclose related party information for our transactions with Vanguard. As part of our overall investment diversification, we may invest in various Vanguard funds from time to time. During 2018 , we purchased $11.5 million in a Vanguard ETF and recorded dividend income of $0.4 million , with no amounts payable on the settlement of this transaction at December 31, 2018 . The market value of this fund in our investment portfolio at December 31, 2018 was $10.5 million . There were no transactions with Vanguard in 2017 and 2016 . Our Pension Plan contained investments in Vanguard funds of $86.3 million at December 31, 2017 , but no investment in these funds existed at December 31, 2018 . We recorded a net investment loss on these funds of $5.5 million in 2018, net investment income of $9.1 million in 2017, and net investment income of $5.4 million in 2016. In addition, our Deferred Compensation Plan and Retirement Savings Plan may offer our employees the option to invest in various Vanguard funds. All transactions with Vanguard are consummated in the ordinary course of business on an arm's-length basis.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies (a) We purchase annuities from life insurance companies to fulfill obligations under claim settlements that provide for periodic future payments to claimants. As of December 31, 2018 , we had purchased such annuities with a present value of $21.0 million for settlement of claims on a structured basis for which we are contingently liable. To our knowledge, there are no material defaults from any of the issuers of such annuities. (b) We have various operating leases for office space, equipment, and fleet vehicles. Such lease agreements, which expire at various times, are generally renewed or replaced by similar leases. Rental expense under these leases amounted to $10.4 million in 2018 , $10.8 million in 2017 , and $12.3 million in 2016 . We also lease computer hardware and software under capital lease agreements expiring at various dates through 2022 . See item (p) of Note 2. "Summary of Significant Accounting Policies" in this Form 10-K for information on our accounting policy regarding leases. In addition, certain of these leases are non-cancelable, and liability for payment will continue even though the leased asset may no longer be in use. At December 31, 2018 , the total future minimum rental commitments under non-cancelable leases were as follows: ($ in millions) Capital Leases Operating Leases Total 2019 $ 0.7 7.8 8.5 2020 0.1 7.4 7.5 2021 — 5.1 5.1 2022 — 3.6 3.6 2023 — 2.9 2.9 After 2023 — 9.7 9.7 Total minimum payment required $ 0.8 36.5 37.3 (c) As of December 31, 2018 , we had contractual obligations that expire at various dates through 2036 to invest up to an additional $202.3 million in alternative and other investments. There is no certainty that any such additional investment will be required. For additional information regarding these investments, see item (f) of Note 5. "Investments" in this Form 10-K. In addition, as of December 31, 2018 , we had the following contractual obligations: (i) $17.8 million to further invest in non-publicly traded common stock within our equity portfolio that expire in 2023 ; and (ii) $40.4 million to further invest in non-publicly traded CLOs in our fixed income securities portfolio that expire through 2030 . We expect to have the capacity to repay and/or refinance these obligations as they become due.

Litigation

Litigation	12 Months Ended
	Dec. 31, 2018
Loss Contingency, Information about Litigation Matters [Abstract]
Litigation	Litigation In the ordinary course of conducting business, we are named as defendants in various legal proceedings. Most of these proceedings are claims litigation involving our Insurance Subsidiaries as either: (i) liability insurers defending or providing indemnity for third-party claims brought against our customers; or (ii) insurers defending first-party coverage claims brought against them. We account for such activity through the establishment of unpaid loss and loss expense reserves. We expect that any potential ultimate liability in such ordinary course claims litigation will not be material to our consolidated financial condition, results of operations, or cash flows after consideration of provisions made for potential losses and costs of defense. From time to time, our Insurance Subsidiaries also are named as defendants in other legal actions, some of which assert claims for substantial amounts. These actions include, among others, putative class actions seeking certification of a state or national class. Such putative class actions have alleged, for example, improper reimbursement of medical providers paid under workers compensation and personal and commercial automobile insurance policies. Similarly, our Insurance Subsidiaries are also named from time-to-time in individual actions seeking extra-contractual damages, punitive damages, or penalties, some of which allege bad faith in the handling of insurance claims. We believe that we have valid defenses to these cases. We expect that any potential ultimate liability in any such lawsuit will not be material to our consolidated financial condition, after consideration of provisions made for estimated losses. Nonetheless, given the inherent unpredictability of litigation and the large or indeterminate amounts sought in certain of these actions, an adverse outcome in certain matters could possibly have a material adverse effect on our consolidated results of operations or cash flows in particular quarterly or annual periods. As of December 31, 2018 , we do not believe the Company was involved in any legal action that could have a material adverse effect on our consolidated financial condition, results of operations, or cash flows.

Statutory Financial Information

Statutory Financial Information, Capital Requirements, and Restrictions on Dividends and Transfers of Funds	12 Months Ended
	Dec. 31, 2018
Insurance [Abstract]
Statutory Financial Information, Capital Requirments, and Retrictions on Dividends and Transfers of Funds	Statutory Financial Information, Capital Requirements, and Restrictions on Dividends and Transfers of Funds (a) Statutory Financial Information The Insurance Subsidiaries prepare their statutory financial statements in accordance with accounting principles prescribed or permitted by the various state insurance departments of domicile. Prescribed statutory accounting principles include state laws, regulations, and general administrative rules, as well as a variety of publications of the National Association of Insurance Commissioners (“NAIC"). Permitted statutory accounting principles encompass all accounting principles that are not prescribed; such principles differ from state to state, may differ from company to company within a state and may change in the future. The Insurance Subsidiaries do not utilize any permitted statutory accounting principles that affect the determination of statutory surplus, statutory net income, or risk-based capital (“RBC”). As of December 31, 2018 , the various state insurance departments of domicile have adopted the March 2018 version of the NAIC Accounting Practices and Procedures manual in its entirety, as a component of prescribed or permitted practices. The following table provides statutory data for each of our Insurance Subsidiaries: State of Domicile Unassigned Surplus Statutory Surplus Statutory Net Income ($ in millions) 2018 2017 2018 2017 2018 2017 2016 SICA New Jersey $ 478.6 455.5 632.8 609.7 78.0 84.6 72.2 Selective Way Insurance Company ("SWIC") New Jersey 300.2 276.1 349.3 325.1 47.5 43.6 41.2 SICSC Indiana 119.4 112.9 150.7 144.1 16.5 17.9 17.4 SICSE Indiana 92.2 86.2 117.7 111.8 12.9 14.7 13.4 SICNY New York 86.5 78.8 114.2 106.5 12.0 13.4 12.9 Selective Insurance Company of New England ("SICNE") New Jersey 19.9 16.1 50.0 46.3 5.6 6.3 5.9 Selective Auto Insurance Company of New Jersey ("SAICNJ") New Jersey 50.3 42.1 93.2 84.9 9.9 11.4 11.5 MUSIC New Jersey 23.0 21.4 91.5 89.9 9.4 10.3 9.7 Selective Casualty Insurance Company ("SCIC") New Jersey 44.9 34.5 119.3 109.0 13.3 13.4 12.6 Selective Fire and Casualty Insurance Company ("SFCIC") New Jersey 17.8 13.7 49.7 45.6 5.5 5.6 5.5 Total $ 1,232.8 1,137.3 1,768.4 1,672.9 210.6 221.2 202.3 (b) Capital Requirements The Insurance Subsidiaries are required to maintain certain minimum amounts of statutory surplus to satisfy the requirements of their various state insurance departments of domicile. RBC requirements for property and casualty insurance companies are designed to assess capital adequacy and to raise the level of protection that statutory surplus provides for policyholders. The Insurance Subsidiaries' combined total adjusted capital exceeded the authorized control level RBC, as defined by the NAIC based on their 2018 statutory financial statements. In addition to statutory capital requirements, we are impacted by various rating agency requirements related to certain rating levels. These required capital levels may be more than statutory requirements. (c) Restrictions on Dividends and Transfers of Funds Our ability to declare and pay dividends on the Parent's common stock is dependent on liquidity at the Parent coupled with the ability of the Insurance Subsidiaries to declare and pay dividends, if necessary, and/or the availability of other sources of liquidity to the Parent. In addition to regulatory restrictions on the availability of dividends that our Insurance Subsidiaries can pay to the Parent, the maximum amount of dividends the Parent can pay our shareholders is limited by certain New Jersey corporate law provisions that limit dividends if either: (i) the Parent would be unable to pay its debts as they became due in the usual course of business; or (ii) the Parent’s total assets would be less than its total liabilities. The Parent’s ability to pay dividends to shareholders also are impacted by covenants in its Line of Credit agreement that obligate it, among other things, to maintain a minimum consolidated net worth, statutory surplus, and debt-to-capital ratio. As of December 31, 2018 , the Parent had an aggregate of $146.0 million in investments and cash available to fund future dividends and interest payments. These amounts are not subject to any regulatory restrictions other than the standard state insolvency restrictions noted above, whereas our consolidated retained earnings of $1.9 billion is predominately restricted due to the regulation associated with our Insurance Subsidiaries. In 2019 , the Insurance Subsidiaries have the ability to provide for $210.0 million in annual dividends to the Parent; however, as regulated entities, these dividends are subject to certain restrictions, which are further discussed below. The Parent also has available to it other potential sources of liquidity, such as: (i) borrowings from our Indiana Subsidiaries; (ii) debt issuances; (iii) common stock issuances; and (iv) borrowings under our Line of Credit. Borrowings from our Indiana Subsidiaries are governed by approved intercompany lending agreements with the Parent that provide for additional capacity of $70.5 million as of December 31, 2018 , based on restrictions in these agreements that limit borrowings to 10% of the admitted assets of the Indiana Subsidiaries. For additional restrictions on the Parent's debt, see Note 10. "Indebtedness" in this Form 10-K. Insurance Subsidiaries Dividend Restrictions As noted above, the restriction on our net assets and retained earnings is predominantly driven by our Insurance Subsidiaries' ability to pay dividends to the Parent under applicable laws and regulations. Under the insurance laws of the domiciliary states of the Insurance Subsidiaries, New Jersey, Indiana, and New York, an insurer can potentially make an ordinary dividend payment if its statutory surplus following such dividend is reasonable in relation to its outstanding liabilities, is adequate to its financial needs, and the dividend does not exceed the insurer's unassigned surplus. In general, New Jersey defines an ordinary dividend as a dividend whose fair market value, together with other dividends made within the preceding 12 months, is less than the greater of 10% of the insurer's statutory surplus as of the preceding December 31, or the insurer's net income (excluding capital gains) for the 12-month period ending on the preceding December 31 . Indiana's ordinary dividend calculation is consistent with New Jersey's, except that it does not exclude capital gains from net income. In general, New York defines an ordinary dividend as a dividend whose fair market value, together with other dividends made within the preceding 12 months, is less than the lesser of 10% of the insurer's statutory surplus, or 100% of adjusted net investment income. New Jersey and Indiana require notice of the declaration of any ordinary dividend distribution. During the notice period, the relevant state regulatory authority may disallow all or part of the proposed dividend if it determines that the dividend is not appropriate given the above considerations. New York does not require notice of ordinary dividends. Dividend payments exceeding ordinary dividends are referred to as extraordinary dividends and require review and approval by the applicable domiciliary insurance regulatory authority prior to payment. The table below provides the following information: (i) quantitative data regarding all Insurance Subsidiaries' dividends paid to the Parent in 2018 for debt service, shareholder dividends, and general operating purposes; and (ii) the maximum ordinary dividends that can be paid to the Parent by the Insurance Subsidiaries in 2019 , based on the 2018 statutory financial statements. Dividends Twelve Months ended December 31, 2018 2019 ($ in millions) State of Domicile Ordinary Dividends Paid Maximum Ordinary Dividends SICA New Jersey $ 43.0 $ 78.0 SWIC New Jersey 19.0 47.5 SICSC Indiana 10.0 16.5 SICSE Indiana 7.5 12.9 SICNY New York 4.5 11.4 SICNE New Jersey 2.0 5.6 SAICNJ New Jersey 2.5 9.9 MUSIC New Jersey 7.1 9.4 SCIC New Jersey 3.0 13.3 SFCIC New Jersey 1.5 5.5 Total $ 100.1 $ 210.0

Quarterly Financial Information

Quarterly Financial Information	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	Quarterly Financial Information First Quarter Second Quarter Third Quarter Fourth Quarter 1 (unaudited, $ in thousands, except per share data) 2018 2017 2018 2017 2018 2017 2018 2017 Net premiums earned $ 591,828 560,854 604,836 568,030 614,277 572,055 625,288 590,088 Net investment income earned 43,231 37,419 45,553 41,430 52,443 40,446 54,109 42,587 Net realized and unrealized (losses) gains 2 (10,549 ) (1,045 ) (1,652 ) 1,734 (4,787 ) 6,798 (37,935 ) (1,128 ) Other income 2,179 3,241 3,179 3,291 2,538 1,994 1,542 2,190 Total revenues 626,689 600,469 651,916 614,485 664,471 621,293 643,004 633,737 Income before federal income taxes 19,931 67,574 72,525 58,929 67,130 67,315 52,135 68,150 Net income 18,925 50,440 58,819 41,426 55,435 46,718 45,760 30,242 Net income per share: Basic 0.32 0.87 1.00 0.71 0.94 0.80 0.77 0.52 Diluted 0.32 0.85 0.99 0.70 0.93 0.79 0.76 0.51 1 Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information. 2 Effective January 1, 2018, changes in unrealized gains and losses on our equity portfolio are recognized in income through "Net unrealized losses on equity securities" on our Consolidated Statements of Income, as a result of our adoption of ASU 2016-01 . See Note 3. "Adoption of Accounting Pronouncements" above. The addition of all quarters may not agree to annual amounts on the Financial Statements due to rounding.

Schedule I - Summary of Investm

Schedule I - Summary of Investments - Other Than Investments in Related Parties	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract]
Schedule I - Summary of Investments- Other than Investments in Related Parties	Types of investment ($ in thousands) Amortized Cost or Cost Fair Value Carrying Amount Fixed income securities: Held-to-maturity: Obligations of states and political subdivisions $ 17,431 17,969 17,470 Public utilities 4,707 5,264 4,818 All other corporate securities 14,883 15,084 14,822 Total fixed income securities, held-to-maturity 37,021 38,317 37,110 Available-for-sale: U.S. government and government agencies 120,092 121,310 121,310 Foreign government 23,202 23,131 23,131 Obligations of states and political subdivisions 1,121,615 1,138,469 1,138,469 Public utilities 28,464 28,393 28,393 All other corporate securities 1,611,388 1,589,015 1,589,015 Collateralized loan obligation securities and other asset-backed securities 720,193 717,362 717,362 Commercial mortgage-backed securities 527,409 527,078 527,078 Residential mortgage-backed securities 1,118,435 1,128,342 1,128,342 Total fixed income securities, available-for-sale 5,270,798 5,273,100 5,273,100 Equity securities: Common stock: Public utilities 2,416 2,732 2,732 Banks, trusts and insurance companies 7,448 8,331 8,331 Industrial, miscellaneous and all other 125,361 133,664 133,664 Nonredeemable preferred stock 2,889 2,912 2,912 Total equity securities 138,114 147,639 147,639 Short-term investments 323,864 323,864 323,864 Other investments 178,938 178,938 Total investments $ 5,948,735 5,960,651 See accompanying Report of Independent Registered Public Accounting Firm in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

Schedule II - Parent Corporatio

Schedule II - Parent Corporation Finanical Statements	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Schedule II- Parent Corporation Financial Statements	SCHEDULE II SELECTIVE INSURANCE GROUP, INC. (Parent Corporation) Balance Sheets December 31, ($ in thousands, except share amounts) 2018 2017 Assets: Fixed income securities, available-for-sale – at fair value (amortized cost: $111,208 – 2018; $89,799 – 2017) $ 110,098 89,872 Short-term investments 35,358 24,080 Cash 505 534 Investment in subsidiaries 2,057,218 2,013,304 Current federal income tax 14,161 22,266 Deferred federal income tax 10,346 13,239 Other assets 1,186 871 Total assets $ 2,228,872 2,164,166 Liabilities: Long-term debt $ 329,540 329,116 Intercompany notes payable 77,517 78,443 Accrued long-term stock compensation 21,574 37,017 Other liabilities 8,439 6,633 Total liabilities $ 437,070 451,209 Stockholders’ Equity: Preferred stock at $0 par value per share: Authorized shares 5,000,000; no shares issued or outstanding $ — — Common stock of $2 par value per share: Authorized shares: 360,000,000 Issued: 102,848,394 – 2018; 102,284,564 – 2017 205,697 204,569 Additional paid-in capital 390,315 367,717 Retained earnings 1,858,414 1,698,613 Accumulated other comprehensive (loss) income (77,956 ) 20,170 Treasury stock – at cost (shares: 43,899,840 – 2018; 43,789,442 – 2017) (584,668 ) (578,112 ) Total stockholders’ equity 1,791,802 1,712,957 Total liabilities and stockholders’ equity $ 2,228,872 2,164,166 See accompanying Report of Independent Registered Public Accounting Firm. Information should be read in conjunction with the Notes to Consolidated Financial Statements of Selective Insurance Group, Inc. and its subsidiaries. Both items are in Item 8. “Financial Statements and Supplementary Data.” of this Form 10-K. SCHEDULE II (continued) SELECTIVE INSURANCE GROUP, INC. (Parent Corporation) Statements of Income Year ended December 31, ($ in thousands) 2018 2017 2016 Revenues: Dividends from subsidiaries $ 100,060 80,096 61,014 Net investment income earned 3,425 2,044 1,259 Net realized losses (1,567 ) (15 ) (220 ) Total revenues 101,918 82,125 62,053 Expenses: Interest expense 24,652 24,721 24,030 Other expenses 25,446 36,251 35,020 Total expenses 50,098 60,972 59,050 Income before federal income tax 51,820 21,153 3,003 Federal income tax (benefit) expense: Current (14,173 ) (22,187 ) (17,924 ) Deferred 3,141 6,311 (2,143 ) Total federal income tax benefit (11,032 ) (15,876 ) (20,067 ) Net income before equity in undistributed income of subsidiaries 62,852 37,029 23,070 Equity in undistributed income of subsidiaries, net of tax 116,087 131,797 135,425 Net income $ 178,939 168,826 158,495 See accompanying Report of Independent Registered Public Accounting Firm. Information should be read in conjunction with the Notes to Consolidated Financial Statements of Selective Insurance Group, Inc. and its subsidiaries. Both items are in Item 8. “Financial Statements and Supplementary Data.” of this Form 10-K. SCHEDULE II (continued) SELECTIVE INSURANCE GROUP, INC. (Parent Corporation) Statements of Cash Flows Year ended December 31, ($ in thousands) 2018 2017 2016 Operating Activities: Net income $ 178,939 168,826 158,495 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed income of subsidiaries, net of tax (116,087 ) (131,797 ) (135,425 ) Stock-based compensation expense 14,507 12,089 10,449 Net realized losses 1,567 15 220 Amortization – other 567 678 648 Changes in assets and liabilities: (Decrease) increase in accrued long-term stock compensation (15,443 ) 4,988 5,564 Decrease (increase) in net federal income taxes 11,246 3,811 (3,612 ) Increase in other assets (343 ) (60 ) (202 ) Increase in other liabilities 1,712 714 80 Net cash provided by operating activities 76,665 59,264 36,217 Investing Activities: Purchase of fixed income securities, available-for-sale (75,046 ) (58,832 ) (45,789 ) Redemption and maturities of fixed income securities, available-for-sale 6,849 10,465 14,983 Sale of fixed income securities, available-for-sale 45,099 31,819 18,768 Purchase of short-term investments (207,115 ) (185,590 ) (119,501 ) Sale of short-term investments 195,846 179,292 130,841 Net cash used in investing activities (34,367 ) (22,846 ) (698 ) Financing Activities: Dividends to stockholders (42,097 ) (37,045 ) (33,758 ) Acquisition of treasury stock (6,556 ) (6,015 ) (4,992 ) Net proceeds from stock purchase and compensation plans 7,252 7,599 7,811 Excess tax benefits from share-based payment arrangements — — 1,819 Principal payment on borrowings from subsidiaries (926 ) (881 ) (6,839 ) Net cash used in financing activities (42,327 ) (36,342 ) (35,959 ) Net (decrease) increase in cash (29 ) 76 (440 ) Cash, beginning of year 534 458 898 Cash, end of year $ 505 534 458 See accompanying Report of Independent Registered Public Accounting Firm. Information should be read in conjunction with the Notes to Consolidated Financial Statements of Selective Insurance Group, Inc. and its subsidiaries. Both items are in Item 8. “Financial Statements and Supplementary Data.” of this Form 10-K.

Schedule III - Supplementary In

Schedule III - Supplementary Insurance Information	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Abstract]
Schedule III- Supplementary Insurance Information	($ in thousands) Deferred policy acquisition costs Reserve for loss and loss expense Unearned premiums Net premiums earned Net investment income 1 Loss and loss expense incurred Amortization of deferred policy acquisition costs Other operating expenses 2 Net premiums written Standard Commercial Lines Segment $ 206,391 3,283,531 1,020,054 1,912,222 — 1,141,038 412,420 249,660 1,975,683 Standard Personal Lines Segment 18,070 223,223 304,085 304,441 — 206,752 33,617 51,308 309,277 E&S Lines Segment 28,151 387,114 107,793 219,566 — 150,344 49,005 20,912 229,326 Investments Segment — — — — 140,413 — — — — Total $ 252,612 3,893,868 1,431,932 2,436,229 140,413 1,498,134 495,042 321,880 2,514,286 1 Includes “Net investment income earned” and “Total net realized and unrealized (losses) gains” on the Consolidated Statements of Income. 2 “Other operating expenses” of $321,880 reconciles to the Consolidated Statements of Income as follows: Other insurance expenses $ 331,318 Other income (9,438 ) Total $ 321,880 See accompanying Report of Independent Registered Public Accounting Firm in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K. Year ended December 31, 2017 ($ in thousands) Deferred policy acquisition costs Reserve for loss and loss expense Unearned premiums Net premiums earned Net investment income 1 Loss and loss expense incurred Amortization of deferred policy acquisition costs Other operating expenses 2 Net premiums written Standard Commercial Lines Segment $ 193,408 3,165,217 956,173 1,788,499 — 1,008,150 387,552 243,283 1,858,735 Standard Personal Lines Segment 16,952 263,166 295,435 289,701 — 189,294 32,542 56,761 296,775 E&S Lines Segment 24,695 342,857 98,036 212,827 — 147,630 49,142 22,337 215,131 Investments Segment — — — — 168,241 — — — — Total $ 235,055 3,771,240 1,349,644 2,291,027 168,241 1,345,074 469,236 322,381 2,370,641 1 Includes “Net investment income earned” and “Total net realized and unrealized (losses) gains” on the Consolidated Statements of Income. 2 “Other operating expenses” of $322,381 reconciles to the Consolidated Statements of Income as follows: Other insurance expenses $ 333,097 Other income (10,716 ) Total $ 322,381 See accompanying Report of Independent Registered Public Accounting Firm in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K. SCHEDULE III (continued) SELECTIVE INSURANCE GROUP, INC. AND CONSOLIDATED SUBSIDIARIES SUPPLEMENTARY INSURANCE INFORMATION Year ended December 31, 2016 ($ in thousands) Deferred policy acquisition costs Reserve for loss and loss expense Unearned premiums Net premiums earned Net investment income 1 Loss and loss expense incurred Amortization of deferred policy acquisition costs Other operating expenses 2 Net premiums written Standard Commercial Lines Segment $ 181,193 3,098,554 884,976 1,665,483 — 913,506 367,813 237,729 1,745,782 Standard Personal Lines Segment 16,664 286,081 282,111 280,607 — 177,749 34,105 56,334 281,822 E&S Lines Segment 24,707 307,084 95,732 203,482 — 143,542 48,410 18,451 209,684 Investments Segment — — — — 125,817 — — — — Total $ 222,564 3,691,719 1,262,819 2,149,572 125,817 1,234,797 450,328 312,514 2,237,288 1 Includes “Net investment income earned” and “Total net realized and unrealized (losses) gains” on the Consolidated Statements of Income. 2 “Other operating expenses” of $312,514 reconciles to the Consolidated Statements of Income as follows: Other insurance expenses $ 321,395 Other income (8,881 ) Total $ 312,514 See accompanying Report of Independent Registered Public Accounting Firm in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

Schedule IV - Reinsurance

Schedule IV - Reinsurance	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
Schedule IV - Reinsurance	($ thousands) Direct Amount Assumed from Other Companies Ceded to Other Companies Net Amount % of Amount Assumed to Net 2018 Premiums earned: Accident and health insurance $ 19 — 19 — — Property and liability insurance 2,808,745 25,831 398,347 2,436,229 1 % Total premiums earned 2,808,764 25,831 398,366 2,436,229 1 % 2017 Premiums earned: Accident and health insurance $ 24 — 24 — — Property and liability insurance 2,647,464 25,831 382,268 2,291,027 1 % Total premiums earned 2,647,488 25,831 382,292 2,291,027 1 % 2016 Premiums earned: Accident and health insurance $ 32 — — 32 — Property and liability insurance 2,484,683 28,214 363,357 2,149,540 1 % Total premiums earned 2,484,715 28,214 363,357 2,149,572 1 % See accompanying Report of Independent Registered Public Accounting Firm in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

Schedule V - Allowance for Unco

Schedule V - Allowance for Uncollectible Premiums and Other Receivables	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule V - Allowance for Uncollectible Premiums and Other Receivables	($ in thousands) 2018 2017 2016 Balance, January 1 $ 14,600 11,480 10,122 Additions 4,022 6,414 4,669 Deductions (4,722 ) (3,294 ) (3,311 ) Balance, December 31 $ 13,900 14,600 11,480 See accompanying Report of Independent Registered Public Accounting Firm in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements (“Financial Statements”) include the accounts of the Parent and its subsidiaries, and have been prepared in conformity with: (i) U.S. generally accepted accounting principles ("GAAP"); and (ii) the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of our Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported financial statement balances, as well as the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
Reclassifications	Reclassifications Certain amounts in our prior years' Financial Statements and related notes have been reclassified to conform to the 2018 presentation. Specifically, we reclassified restricted cash balances related to our participation in the National Flood Insurance Program ("NFIP") from other assets in our consolidated balance sheet into a separate line item on the face of that statement. Additionally, refer to Note 3. "Adoption of Accounting Pronouncements" below for a discussion of the retroactive restatements that are included in these financial statements in relation to the adoption of new accounting pronouncements for the treatment of restricted cash and distributions from equity method investments on the Consolidated Statements of Cash Flows.
Investments	Investments Portfolio Composition and Presentation in the Consolidated Balance Sheets Our investment portfolio is primarily comprised of fixed income securities, which represent approximately 89% of our invested assets. We also hold equity securities, short-term investments, and other investments. A description of our portfolio holdings, and the related presentation in our Consolidated Balance Sheets, is provided below. Fixed Income Portfolio We hold the following types of securities in our fixed income securities portfolio: • U.S. government and government agencies; • Foreign government obligations; • State and municipal obligations, including special revenue and general obligation bonds; • Corporate securities, which may include investment grade and below investment grade bonds, bank loan investments, redeemable preferred stock, and non-redeemable preferred stock with certain debt-like characteristics; • Collateralized loan obligations ("CLOs") and other asset-backed securities ("ABS"); • Residential mortgage-backed securities ("RMBS"); and • Commercial mortgage-backed securities ("CMBS"). We have designated approximately 99% of our fixed income securities portfolio as available-for-sale ("AFS"), with the remaining 1% being designated as held-to-maturity ("HTM"), as we have the ability and positive intent to hold these securities to maturity. Our AFS securities are reported at fair value in our consolidated balance sheets, with unrealized gains or losses recognized in accumulated other comprehensive income (loss) ("AOCI"), net of tax. HTM securities are carried at either: (i) amortized cost; or (ii) market value at the date of transfer into the HTM category, adjusted for subsequent amortization. After-tax unrealized gains and losses on securities that were transferred into an HTM designation from an AFS designation, are also included in AOCI. The amortized cost of fixed income securities is adjusted for the amortization of premiums and the accretion of discounts over the expected life of the security using the effective yield method. Callable debt securities held at a premium are amortized to the earliest call date. Premiums and discounts arising from the purchase of RMBS, CMBS, CLOs and other ABS are amortized over the expected life of the security based on future principal payments, giving additional consideration to prepayments. These prepayments are estimated based on historical and projected cash flows. Prepayment assumptions are reviewed quarterly and adjusted to reflect actual prepayments and changes in expectations. Future amortization of any premium and/or discount is adjusted to reflect the revised assumptions. Other Portfolio Holdings Equity securities may include common and non-redeemable preferred stocks. Equity securities with readily determinable fair values are carried at fair value. Certain equity securities without readily determinable fair values are carried at net asset value ("NAV") as a practical expedient. Short-term investments may include certain money market instruments, savings accounts, commercial paper, and debt issues purchased with a maturity of less than one year. We also enter into reverse repurchase agreements that are included in short-term investments. These loans are fully collateralized with high quality, readily marketable instruments at a minimum of 102% of the loan principal. At maturity, we receive principal and interest income on these agreements. All short-term investments are carried at cost, which approximates fair value. Other investments may include alternative investments and other securities. Alternative investments are accounted for using the equity method, with income typically recognized on a one-quarter lag. Other securities are primarily comprised of tax credit investments and equity securities without readily determinable fair values that are not carried at NAV as a practical expedient. These equity securities are carried at cost. Accounting for our tax credit investments is dependent on the type of credit we have purchased, as follows: • Federal low income housing tax credits are accounted for under the proportional amortization method; and • All other tax credits in our investment portfolio are accounted for using the equity method. For federal tax credits accounted for under the equity method, we use the deferral method for recognizing the benefit of the tax credit with the related deferred revenue being recognized in our Consolidated Income Statement as a component of "Federal income tax expense" proportionately over the life of the investment. We evaluate the alternative investments and tax credit investments included in our other investments portfolio to determine whether those investments are variable interest entities ("VIEs") and if so, whether consolidation is required. A VIE is an entity that either has equity investors that lack certain essential characteristics of a controlling financial interest or lack sufficient funds to finance its own activities without financial support provided by other entities. We consider several significant factors in determining if our investments are VIEs and if we are the primary beneficiary, including whether we have: (i) the power to direct activities of the VIE; (ii) the ability to remove the decision maker of the VIE; (iii) the ability to participate in making decisions that are significant to the VIE; and (iv) the obligation to absorb losses and the right to receive benefits that could potentially be significant to the VIE. We have reviewed our alternative and tax credit investments and have concluded that they are VIEs, but that we are not the primary beneficiary and therefore, consolidation is not required. Presentation in the Consolidated Statements of Income Net investment income earned on our Consolidated Statements of Income include the following: • Interest income, as well as amortization and accretion, on fixed income securities; • Dividend income on equity securities; • Interest income on our short-term investments; and • Income recognized on our alternative and other investments accounted for under the equity method of accounting, except for federal tax credits, as discussed below. Income related to federal tax credits (either low income housing tax credits or other federal credits) is recorded in our Consolidated Statements of Income as a component of “Federal income tax expense” proportionately over the life of the investment. Net realized and unrealized gains and losses on our Consolidated Statements of Income include the following: • Realized gain and losses on the disposal of investment securities, which are determined on the basis of the cost of the specific investments sold; • Other-than-temporary impairment ("OTTI") charges that are credit related or related to our intent to sell; and • Changes in unrealized gains or losses on our equity securities that are carried at fair value. On a quarterly basis, we review our investment portfolio for impairments that are other than temporary. The following provides information on this analysis for our fixed income securities and short-term investments, and our other investments. OTTI Charges on Fixed Income Securities and Short-Term Investments We review our fixed income securities and short-term investments that are in an unrealized loss position to determine: (i) if we have the intent to sell the security; (ii) if it is more likely than not that we will be required to sell the security before its anticipated recovery; (iii) if the decline is other than interest-rate related; and (iv) if the decline is other than temporary. Broad changes in the overall market or interest rate environment generally will not lead to a write down. If we determine that we have either the intent or requirement to sell the security, we write down its amortized cost to its fair value through an OTTI charge to earnings. If we do not have either the intent or requirement to sell the security, our evaluation for OTTI may include, but is not limited to, evaluation of the following factors: • Whether the decline appears to be issuer or industry specific; • The degree to which the issuer is current or in arrears in making principal and interest payments on the fixed income security; • The issuer’s current financial condition and ability to make future scheduled principal and interest payments on a timely basis; • Evaluation of projected cash flows; • Buy/hold/sell recommendations published by outside investment advisors and analysts; and • Relevant rating history, analysis, and guidance provided by rating agencies and analysts. To determine if an impairment is other than temporary, we perform assessments that may include, but are not limited to, a discounted cash flow analysis ("DCF") to determine the security's present value of future cash flows. This analysis is also performed on all previously-impaired debt securities that continue to be held by us and all RMBS, CMBS, CLOs and ABS that were not of high credit quality at the date of purchase. Any shortfall in the expected present value of the future cash flows, based on the DCF, from the amortized cost basis of a security is considered a “credit impairment,” with the remaining decline in fair value of a security considered a “non-credit impairment.” Credit impairments are charged to earnings as a component of realized losses, while non-credit impairments are recorded to other comprehensive income ("OCI") as a component of unrealized losses. The discount rate we use in a DCF is the effective interest rate implicit in the security at the date of acquisition for those RMBS, CMBS, CLOs and other ABS that were not of high credit quality at acquisition. For all other securities, we use a discount rate that equals the current yield, excluding the impact of previous OTTI charges, used to accrete the beneficial interest. DCFs may include, but are not necessarily limited to: (i) generating cash flows for each tranche considering tranche-specific data, market data, and other pertinent information, such as the historical performance of the underlying collateral, including net operating income generated by underlying properties, conditional default rate assumptions, loan loss severity assumptions, consensus projections, prepayment projections, and actual pool and collateral information; (ii) identifying applicable benchmark yields; and (iii) applying market-based tranche specific spreads to determine an appropriate yield by incorporating collateral performance, tranche-level attributes, trades, bids, and offers. Non-redeemable preferred stocks that are classified as fixed income securities are evaluated using the OTTI method described above unless the security is below investment grade. In this situation, we would determine: (i) if we do not intend to hold the security to its forecasted recovery; or (ii) if the decline is other than temporary, which includes declines driven by market volatility for which we cannot assert recovery in the near term. If we determine either that we do not intend to hold the security, or the decline is other than temporary, we write down the security's cost to its fair value through an OTTI charge to earnings. OTTI Charges on Other Investments Our evaluation for OTTI of an alternative investment may include, but is not limited to, conversations with the management of the alternative investment concerning the following: • The current investment strategy; • Changes made or future changes to be made to the investment strategy; • Emerging issues that may affect the success of the strategy; and • The appropriateness of the valuation methodology used regarding the underlying investments. Our evaluation for OTTI of our other investments (tax credits and equity securities without a readily determinable fair value for which NAV is not used as a practical expedient) include a qualitative assessment of impairment indicators, which include, but are not limited to, the following: • A significant deterioration in the earnings performance, credit ratings, asset quality, or business prospects of the investee; • A significant adverse change in the regulatory, economic, or technological environment of the investee; • A significant adverse change in the general market condition of either the geographical area or the industry in which the investee operates; • A bona fide offer to purchase, or an offer by the investee to sell, or a completed auction process for the same or similar investment for an amount less than the carrying amount of that investment; and • Factors that raise significant concerns about the investee's ability to continue as a going concern, such as negative cash flows from operations, working capital deficiencies, or noncompliance with statutory capital requirements or debt covenants. If there is a decline in the fair value of an alternative or other investment that we do not intend to hold, or if we determine the decline is other than temporary, we write down the carry value of the investment through an OTTI charge to earnings.
Fair Value of Financial Instruments	Fair Values of Financial Instruments Assets The fair values of our investments are generated using various valuation techniques and are placed into the fair value hierarchy considering the following: (i) the highest priority is given to quoted prices in active markets for identical assets (Level 1); (ii) the next highest priority is given to quoted prices in markets that are not active or inputs that are observable either directly or indirectly, including quoted prices for similar assets in markets that are not active and other inputs that can be derived principally from, or corroborated by, observable market data for substantially the full term of the assets (Level 2); and (iii) the lowest priority is given to unobservable inputs supported by little or no market activity and that reflect our assumptions about the exit price, including assumptions that market participants would use in pricing the asset (Level 3). An asset’s classification within the fair value hierarchy is based on the lowest level of significant input to its valuation. Transfers between levels in the fair value hierarchy are recognized at the end of the reporting period. The techniques used to value our financial assets are as follows: Level 1 Pricing Security Type Methodology Equity Securities; U.S. Treasury Notes Equity and U.S. Treasury Note prices are received from an independent pricing service that are based on observable market transactions. We validate these prices against a second external pricing service, and if established market value comparison thresholds are breached, further analysis is performed to determine the price to be used. Short-Term Investments Short-term investments are carried at cost, which approximates fair value. Given the liquid nature of our short-term investments, we generally validate their fair value by way of active trades within approximately one week of the financial statement close. Level 2 Pricing We utilize a market approach for our Level 2 securities, using primarily matrix pricing models prepared by external pricing services. Matrix pricing models use mathematical techniques to value debt securities by relying on the securities' relationship to other benchmark quoted securities, and not relying exclusively on quoted prices for specific securities, as the specific securities are not always frequently traded. As a matter of policy, we consistently use one pricing service as our primary source and secondary pricing services if prices are not available from the primary pricing service. Fixed income securities portfolio pricing is reviewed for reasonableness in the following ways: (i) comparing our pricing to other third-party pricing services as well as benchmark indexed pricing; (ii) comparing fair value fluctuations between months for reasonableness; and (iii) reviewing stale prices. If further analysis is needed, a challenge is sent to the pricing service for review and confirmation of the price. Further information on our Level 2 asset pricing is included in the following table: Security Type Methodology Corporate Securities including preferred stocks classified as Fixed Income Securities, and U.S. Government and Government Agencies Evaluations include obtaining relevant trade data, benchmark quotes and spreads, and incorporating this information into either spread-based or price-based evaluations as determined by the observed market data. Spread-based evaluations include: (i) creating a range of spreads for relevant maturities of each issuer based on the new issue market, secondary trading, and dealer quotes; and (ii) incorporating option adjusted spreads for issues that have early redemption features. Based on the findings in (i) and (ii) above, final spreads are derived and added to benchmark curves. Price-based evaluations include matching each issue to its best-known market maker and contacting firms that transact in these securities. Obligations of States and Political Subdivisions Evaluations are based on yield curves that are developed based on factors such as: (i) benchmarks to issues with interest rates near prevailing market rates; (ii) established trading spreads over widely-accepted market benchmarks; (iii) yields on new issues; and (iv) market information from third-party sources such as reportable trades, broker-dealers, or issuers. RMBS, CMBS, CLOs and other ABS Evaluations are based on a DCF, including: (i) generating cash flows for each tranche considering tranche-specific data, market data, and other pertinent information, such as historical performance of the underlying collateral, including net operating income generated by the underlying properties, conditional default rate assumptions, loan loss severity assumptions, consensus projections, prepayment projections, and actual pool and loan level collateral information; (ii) identifying applicable benchmark yields; and (iii) applying market-based tranche-specific spreads to determine an appropriate yield by incorporating collateral performance, tranche-level attributes, trades, bids, and offers. Foreign Government Evaluations are performed using a DCF model and by incorporating observed market yields of benchmarks as inputs, adjusting for varied maturities. Level 3 Pricing Less than 1% of our portfolio cannot be priced using our primary or secondary pricing service. At times, we may use valuations performed by the issuer or non-binding broker quotes to determine the fair value of these securities. We internally review these fair value measurements for reasonableness. This review typically includes an analysis of price fluctuations between months with variances over established thresholds being analyzed further. Liabilities The techniques used to value our notes payable are as follows: Level 1 Pricing Security Type Methodology 5.875% Senior Notes Based on the quoted market prices. Level 2 Pricing Security Type Methodology 7.25% Senior Notes; 6.70% Senior Notes Based on matrix pricing models prepared by external pricing services. Borrowings from Federal Home Loan Banks Evaluations are performed using a DCF model based on current borrowing rates provided by the Federal Home Loan Banks that are consistent with the remaining term of the borrowing.
Allowance for Uncollectible Accounts	Allowance for Uncollectible Accounts We estimate an allowance for uncollectible accounts on our premiums receivable. This allowance is based on historical write-off percentages adjusted for the effects of current and anticipated trends. An account is charged off when we believe it is probable that we will not collect a receivable. In making this determination, we consider information obtained from our efforts to collect amounts due directly or through collection agencies.
Share-Based Compensation	Share-Based Compensation Share-based compensation consists of all share-based payment transactions in which an entity acquires goods or services by issuing (or offering to issue) its shares, share units, share options, or other equity instruments. The cost resulting from all share-based payment transactions are recognized in the Financial Statements based on the fair value of both equity and liability awards. The fair value is measured at grant date for equity awards, whereas the fair value for liability awards are remeasured at each reporting period. The fair value of both equity and liability awards is recognized over the requisite service period. The requisite service period is typically the lesser of the vesting period or the period of time from the grant date to the date of retirement eligibility. The expense recognized for share-based awards, which, in some cases, contain performance criteria, is based on the number of shares or units expected to be issued at the end of the performance period. We repurchase the Parent’s stock from our employees in connection with tax withholding obligations, as permitted under our stock-based compensation plans. This activity is disclosed in our Consolidated Statements of Stockholders' Equity.
Reinsurance	Reinsurance Reinsurance recoverable represents estimates of amounts that will be recovered from reinsurers under our various treaties. Generally, amounts recoverable from reinsurers are recognized as assets at the same time and in a manner consistent with the paid and unpaid losses associated with the reinsured policies. We require collateral to secure reinsurance recoverables primarily from our reinsurance carriers that are not authorized, otherwise approved, or certified to do business in one or more of our ten insurance subsidiaries' domiciliary states. Our ten insurance subsidiaries are collectively referred to as the "Insurance Subsidiaries." This collateral is typically in the form of a letter of credit or cash. An allowance for estimated uncollectible reinsurance is recorded based on an evaluation of balances due from reinsurers and other available information, such as each reinsurer's credit rating from A.M. Best Company ("A.M. Best") or Standard & Poor's Rating Services ("S&P"). We charge off reinsurance recoverables on paid losses when it becomes probable that we will not collect the balance.
Property and Equipment	Property and Equipment Property and equipment used in operations, including certain costs incurred to develop or obtain computer software for internal use, are capitalized and carried at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. The following estimated useful lives can be considered as general guidelines: Asset Category Years Computer hardware 3 Computer software 3 to 5 Internally developed software 5 to 10 Software licenses 3 to 5 Furniture and fixtures 10 Buildings and improvements 5 to 40 We recorded depreciation expense of $19.5 million , $17.8 million , and $17.4 million for 2018 , 2017 , and 2016 , respectively.
Deferred Policy Acquisition Costs	Deferred Policy Acquisition Costs Deferred policy acquisition costs are limited to costs directly related to the successful acquisition of insurance contracts. Costs meeting this definition typically include, among other things, sales commissions paid to our distribution partners, premium taxes, and the portion of employee salaries and benefits directly related to time spent on acquired contracts. These costs are deferred and amortized over the life of the contracts. Accounting guidance requires a premium deficiency analysis to be performed at the level an entity acquires, services, and measures the profitability of its insurance contracts. We currently perform three premium deficiency analyses for our insurance operations, consistent with our reportable segments of Standard Commercial Lines, Standard Personal Lines, and E&S Lines. A combined ratio of over 100% does not necessarily indicate a premium deficiency, as any year's combined ratio includes a portion of underwriting expenses that are expensed at policy inception and therefore are not covered by the remaining unearned premium. In addition, investment income is not contemplated in the combined ratio calculation. There were no premium deficiencies for any of the reported years, as the sum of the anticipated loss and loss expense, unamortized acquisition costs, policyholder dividends, and other expenses for each segment did not exceed that segment’s related unearned premium and anticipated investment income. The investment yields assumed in the premium deficiency assessment for each reporting period, which were based on our actual average investment yield before tax as of the September 30 calculation date, were 3.3% for 2018 , 2.9% for 2017 , and 2.4% for 2016 .
Goodwill	Goodwill Goodwill results from business acquisitions where the cost of assets and liabilities acquired exceeds the fair value of those assets and liabilities. A quantitative goodwill impairment analysis is performed if our quarterly qualitative analysis indicates that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. Goodwill is allocated to the reporting units for purposes of these analyses. Based on our analysis at December 31, 2018 , goodwill was not impaired.
Reserve for Loss and Loss Expense	Reserve for Loss and Loss Expense Reserves for loss and loss expense are comprised of both case reserves on individual claims and reserves for claims incurred but not reported ("IBNR"). Case reserves result from claims that have been reported to one or more of our Insurance Subsidiaries, and are estimated at the amount of the expected ultimate payment. IBNR reserves are established at more aggregated levels than case basis reserves, and include: (i) reserves on IBNR claims; and (ii) provisions for future emergence on known or reopened claims. IBNR reserves are established based on the results of the Insurance Subsidiaries’ internal reserve analysis, supplemented with other internal and external information. The internal reserve analysis is performed quarterly, and relies upon generally accepted actuarial techniques. Such techniques assume that past experience, adjusted for the effects of current developments and anticipated trends, are an appropriate basis for predicting future events. Our analyses rely upon historical paid and case loss and loss expense experience organized by line of business, accident year, and maturity (i.e., “triangles”). Standard actuarial projection methods are applied to this history, producing a set of estimated ultimate loss and loss expenses. Ultimate loss and loss expenses are selected from the various methods, considering the strengths and weaknesses of the methods as they apply to the specific line and accident year. Certain types of exposures do not lend themselves to standard actuarial methods. Examples of these are: • Certain property catastrophe events may be low in frequency and high in severity. These events may affect many insureds simultaneously. Due to the unique nature of these events, ultimate liabilities are estimated for each event, based on surveys of our portfolio of exposures, in conjunction with individual claims estimates. While generally short-tailed, the liabilities associated with these events are subject to a higher degree of uncertainty. We maintain significant reinsurance protection that greatly limits the impact that these extreme events have on net loss and loss expenses. • Some insured events may span multiple years and trigger multiple policies, as in the case of asbestos and environmental claims, where the injury is deemed to occur over an extended period of time. These types of losses often do not lend themselves to traditional actuarial methods. Where we deem appropriate, our experience may be analyzed without differentiating by accident year, using alternative methods and metrics. In these cases, the associated selected ultimate loss and loss expenses are then allocated to the applicable accident years for reporting. • Another example of non-standard methods relate to loss expenses that cannot be attributed to a specific claim (referred to as “unallocated loss expenses”). These expenses are first allocated to line of business, and alternative projection methods are then applied to estimate expenses by calendar year, which are then allocated back to the applicable accident years for reporting. The selected ultimate loss and loss expenses are translated into indicated IBNR reserves, which are then compared to the recorded IBNR reserves. Management's judgment is applied in determining any required adjustments to IBNR and the resulting adjustments are then recorded and assigned or allocated to accident year using the results of the actuarial analysis. While the reserve analysis is the primary basis for determining the recorded IBNR reserves, other internal and external factors are considered. Internal factors include: (i) supplemental data regarding claims reporting and settlement trends; (ii) exposure estimates for reported claims, along with recent development on those estimates with respect to individual large claims and the aggregate of all claims; (iii) the rate at which new large or complex claims are being reported; and (iv) additional trends observed by claims personnel or reported to them by defense counsel. External factors considered include: (i) legislative enactments; (ii) judicial decisions; (iii) legal developments in the determination of liability and the imposition of damages; (iv) social inflation and heightened awareness of sources of liability; and (v) trends in general economic conditions, including the effects of inflation. Loss reserves are estimates, and as such, we also consider a range of possible loss and loss expense reserve estimates. This range is determined at the beginning of each year, using prior year-end data, and reflects the fact that there is no single precise method for estimating the required reserves, due to the many factors that may influence the amounts ultimately paid. Considering the reserve range along with all of the items described above, as well as current market conditions, IBNR estimates are then established and recorded. The combination of the IBNR estimates along with the case reserve estimates on individual claims results in our total reserves for loss and loss expense. These reserves are expected to be sufficient for settling loss and loss expense obligations under our policies on unpaid claims, including changes in the volume of business written, claims frequency and severity, the mix of business, claims processing, and other items that management expects to affect our ultimate settlement of loss and loss expense. However, the ultimate claim settlements may be higher or lower than reserves established. As our experience emerges and other information develops, we revise our reserve estimates accordingly. The changes in these estimates, resulting from the continuous review process and the differences between estimates and ultimate payments, are reflected in the Consolidated Statements of Income for the period in which such estimates are changed. The associated impacts may be material to the results of operations in future periods. We do not discount to present value that portion of our loss and loss expense reserves expected to be paid in future periods. Our loss and loss expense reserves implicitly include anticipated recoveries for salvage and subrogation claims. Claims are counted at the occurrence, line of business, and policy level. For example, if a single occurrence (e.g. an auto accident) leads to a claim under an auto and an associated umbrella policy, they are each counted separately. Conversely, multiple claimants under the same occurrence/line/policy would contribute only a single count. The claim counts provided are on a reported basis. A claim is considered reported when a reserve is established or a payment is made. Therefore, claims closed without payment are included in the count as long as there was an associated case reserve at some point in its life cycle. We also write a small amount of assumed reinsurance. Currently, this business is limited to our share of certain involuntary pools. As the associated claims are not processed by us, they are not captured within our claims system. Therefore, the claim counts reported exclude this business. (m)
Revenue Recognition	Revenue Recognition The Insurance Subsidiaries' net premiums written (“NPW”) include direct insurance policy writings, plus reinsurance assumed and estimates of premiums earned but unbilled on the workers compensation and general liability lines of business, less reinsurance ceded. The estimated premium on the workers compensation and general liability lines is referred to as audit premium. We estimate this premium, as it is anticipated to be either billed or returned on policies subsequent to expiration based on exposure levels (i.e. payroll or sales). Audit premium is based on historical trends adjusted for the uncertainty of future economic conditions. Economic instability could ultimately impact our estimates and assumptions, and changes in our estimate may be material to the results of operations in future periods. Premiums written are recognized as revenue over the period that coverage is provided using the semi-monthly pro-rata method. Unearned premiums and prepaid reinsurance premiums represent that portion of premiums written that are applicable to the unexpired terms of policies in force.
Dividends to Policyholders	Dividends to Policyholders We establish reserves for dividends to policyholders on certain policies, most significantly workers compensation policies. These dividends are based on the policyholders' loss experience. Dividend reserves are established based on past experience, adjusted for the effects of current developments and anticipated trends. The expense for these dividends is recognized over a period that begins at policy inception and ends with the payment of the dividend. We report these dividends within "Other insurance expenses" on the Consolidated Statements of Income. We do not issue policies that entitle the policyholder to participate in the earnings or surplus of our Insurance Subsidiaries.
Federal Income Tax	Federal Income Tax We use the asset and liability method of accounting for income taxes. Current federal income taxes are recognized for the estimated taxes payable or refundable on tax returns for the current year. Deferred federal income taxes arise from the recognition of temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities. We consider all evidence, both positive and negative, with respect to our federal tax loss carryback availability, expected levels of pre-tax financial statement income, and federal taxable income, when evaluating whether the temporary differences will be realized. In projecting future taxable income, we begin with budgeted pre-tax income adjusted for estimated non-taxable items. The assumptions about future taxable income require significant judgment and are consistent with the plans and estimates we use to manage our businesses. A valuation allowance is established when it is more likely than not that some portion of the deferred tax asset will not be realized. A liability for uncertain tax positions is recorded when it is more likely than not that a tax position will not be sustained upon examination by taxing authorities. The effect of a change in tax rates is recognized in the period of enactment. If we were to be levied interest and penalties by the Internal Revenue Service (“IRS”), the interest would be recognized as “Interest expense” and the penalties would be recognized as either “Other insurance expenses” or "Corporate expenses" on the Consolidated Statements of Income depending on the nature of what caused the occurrence of such an item.
Leases	Leases We have various operating leases for office space, equipment, and fleet vehicles. Rental expense for such leases is recorded on a straight-line basis over the lease term. If a lease has a fixed and determinable escalation clause, or periods of rent holidays, the difference between rental expense and rent paid is included in "Other liabilities" in the Consolidated Balance Sheets. In addition, we have various capital leases for computer hardware and software. These leases are accounted for as an acquisition of an asset with a corresponding obligation. Depreciation is calculated using the straight-line method over the shorter of the estimated useful life of the asset or the lease term.
Pension	Pension Our pension and post-retirement life benefit obligations and related costs are calculated using actuarial methods, within the framework of GAAP. Our pension benefit obligation is determined as the actuarial present value of the vested benefits to which the employee is currently entitled, based on the average life expectancy of the employee. Our funding policy provides that payments to our pension trust shall be equal to the minimum funding requirements of the Employee Retirement Income Security Act of 1974 ("ERISA"), plus additional amounts that the Board of Directors of Selective Insurance Company of America (“SICA”) may approve from time to time. Two key assumptions, the discount rate and the expected return on plan assets, are important elements of expense and/or liability measurement. We evaluate these key assumptions annually unless facts indicate that a more frequent review is required. The discount rate enables us to state expected future cash flows at their present value on the measurement date. The purpose of the discount rate is to determine the interest rates inherent in the price at which pension benefits could be effectively settled. Our discount rate selection is based on high-quality, long-term corporate bonds. To determine the expected long-term rate of return on the plan assets, we consider the current and expected asset allocation, as well as historical and expected returns on each plan asset class. Other assumptions involve demographic factors such as retirement age and mortality.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Estimated Useful Life for Property and Equipment	Asset Category Years Computer hardware 3 Computer software 3 to 5 Internally developed software 5 to 10 Software licenses 3 to 5 Furniture and fixtures 10 Buildings and improvements 5 to 40

Adoption of Accounting Pronou_2

Adoption of Accounting Pronouncements Adoption of Accounting Pronouncements (Tables)	12 Months Ended
	Dec. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	December 31, 2017 December 31, 2016 ($ in thousands) Prior to Adoption After Adoption Prior to Adoption After Adoption Undistributed (gains) losses of equity method investments $ (6,393 ) (5,362 ) $ (2,316 ) 318 Distributions in excess of current year income of equity method investments — 552 — — (Increase) decrease in other assets (9,872 ) (2,643 ) (30,071 ) (4,979 ) Net cash provided by operating activities 370,733 379,545 301,783 329,509 Distributions from other investments 23,426 21,843 26,837 24,202 Net cash used in investing activities (331,075 ) (332,658 ) (318,101 ) (320,736 )

Statements of Cash Flow (Tables

Statements of Cash Flow (Tables)	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	($ in thousands) 2018 2017 2016 Cash paid during the period for: Interest $ 23,992 23,905 22,098 Federal income tax 29,193 62,000 46,405 Non-cash items: Corporate actions related to fixed income securities, AFS 1 52,277 22,511 23,579 Corporate actions related to equity securities 1 944 4,725 3,263 Assets acquired under capital lease arrangements 4,119 278 3,151 Non-cash purchase of property and equipment 291 — 78
Schedule of Cash and Cash Equivalents	($ in thousands) December 31, 2018 December 31, 2017 Cash $ 505 534 Restricted cash 16,414 44,176 Total cash and restricted cash shown in the Statements of Cash Flows $ 16,919 44,710

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Investment [Line Items]
Schedule of Unrealized Gains On Investments	($ in thousands) 2018 2017 2016 AFS securities: Fixed income securities $ 2,302 85,806 38,781 Equity securities — 38,894 25,864 Total AFS securities 2,302 124,700 64,645 HTM securities: Fixed income securities 89 (21 ) 159 Total HTM securities 89 (21 ) 159 Total net unrealized gains 2,391 124,679 64,804 Deferred income tax (502 ) (44,103 ) (22,681 ) Net unrealized gains, net of deferred income tax 1,889 80,576 42,123 Cumulative effect adjustment due to accounting change for equity unrealized 1 30,726 — — Cumulative effect adjustment due to accounting changes due to accounting change for stranded tax assets 1 (17,920 ) — — Increase (decrease) in net unrealized gains in OCI, net of deferred income tax $ (65,881 ) 38,453 (2,873 )
Schedule of Held-to-maturity Securities	December 31, 2018 Net Unrealized Unrecognized Unrecognized Amortized Gains Carrying Holding Holding Fair ($ in thousands) Cost (Losses) Value Gains Losses Value Obligations of state and political subdivisions $ 17,431 39 17,470 504 (5 ) 17,969 Corporate securities 19,590 50 19,640 855 (147 ) 20,348 Total HTM fixed income securities $ 37,021 89 37,110 1,359 (152 ) 38,317 December 31, 2017 Net Unrealized Unrecognized Unrecognized Amortized Gains Carrying Holding Holding Fair ($ in thousands) Cost (Losses) Value Gains Losses Value Obligations of state and political subdivisions 25,154 84 25,238 1,023 — 26,261 Corporate securities 16,996 (105 ) 16,891 1,003 (55 ) 17,839 Total HTM fixed income securities $ 42,150 (21 ) 42,129 2,026 (55 ) 44,100
Schedule of Available For Sale Securities	December 31, 2018 Cost/ Amortized Unrealized Unrealized Fair ($ in thousands) Cost Gains Losses Value AFS fixed income securities: U.S. government and government agencies $ 120,092 1,810 (592 ) 121,310 Foreign government 23,202 36 (107 ) 23,131 Obligations of states and political subdivisions 1,121,615 19,485 (2,631 ) 1,138,469 Corporate securities 1,639,852 5,521 (27,965 ) 1,617,408 CLO and other ABS 720,193 4,112 (6,943 ) 717,362 CMBS 527,409 3,417 (3,748 ) 527,078 RMBS 1,118,435 12,988 (3,081 ) 1,128,342 Total AFS fixed income securities $ 5,270,798 47,369 (45,067 ) 5,273,100 December 31, 2017 Cost/ Amortized Unrealized Unrealized Fair ($ in thousands) Cost Gains Losses Value AFS fixed income securities: U.S. government and government agencies $ 49,326 647 (233 ) 49,740 Foreign government 18,040 526 (11 ) 18,555 Obligations of states and political subdivisions 1,539,307 44,245 (582 ) 1,582,970 Corporate securities 1,588,339 30,891 (1,762 ) 1,617,468 CLO and other ABS 789,152 6,508 (202 ) 795,458 CMBS 382,727 1,563 (841 ) 383,449 RMBS 709,825 6,487 (1,430 ) 714,882 Total AFS fixed income securities 5,076,716 90,867 (5,061 ) 5,162,522 AFS equity securities: Common stock 129,696 38,287 (226 ) 167,757 Preferred stock 14,115 904 (71 ) 14,948 Total AFS equity securities 143,811 39,191 (297 ) 182,705 Total AFS securities $ 5,220,527 130,058 (5,358 ) 5,345,227
Schedule of Fair Value and Gross Pre-Tax Net Unrealized/Unrecognized Loss of Securities by Length of Time	December 31, 2018 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Unrealized AFS fixed income securities: U.S. government and government agencies $ 6,693 (174 ) 23,163 (418 ) 29,856 (592 ) Foreign government 12,208 (93 ) 1,482 (14 ) 13,690 (107 ) Obligations of states and political subdivisions 196,798 (2,074 ) 42,821 (557 ) 239,619 (2,631 ) Corporate securities 1,041,952 (23,649 ) 78,953 (4,316 ) 1,120,905 (27,965 ) CLO and other ABS 516,106 (6,750 ) 16,800 (193 ) 532,906 (6,943 ) CMBS 229,338 (2,548 ) 66,294 (1,200 ) 295,632 (3,748 ) RMBS 139,338 (1,660 ) 45,661 (1,421 ) 184,999 (3,081 ) Total AFS fixed income securities $ 2,142,433 (36,948 ) 275,174 (8,119 ) 2,417,607 (45,067 ) December 31, 2017 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Unrealized AFS fixed income securities: U.S. government and government agencies $ 23,516 (233 ) 250 — 23,766 (233 ) Foreign government 1,481 (11 ) — — 1,481 (11 ) Obligations of states and political subdivisions 107,514 (422 ) 14,139 (160 ) 121,653 (582 ) Corporate securities 238,326 (1,744 ) 3,228 (18 ) 241,554 (1,762 ) CLO and other ABS 74,977 (196 ) 1,655 (6 ) 76,632 (202 ) CMBS 154,267 (773 ) 5,214 (68 ) 159,481 (841 ) RMBS 269,485 (1,285 ) 11,200 (145 ) 280,685 (1,430 ) Total AFS fixed income securities 869,566 (4,664 ) 35,686 (397 ) 905,252 (5,061 ) AFS equity securities: Common stock 4,727 (226 ) — — 4,727 (226 ) Preferred stock 3,833 (71 ) — — 3,833 (71 ) Total AFS equity securities 8,560 (297 ) — — 8,560 (297 ) Total AFS securities $ 878,126 (4,961 ) 35,686 (397 ) 913,812 (5,358 )
Schedule of Investments Classified by Contractual Maturity Date	AFS HTM ($ in thousands) Fair Value Carrying Value Fair Value Due in one year or less $ 188,309 13,502 13,693 Due after one year through five years 2,040,395 17,308 18,260 Due after five years through 10 years 2,863,528 6,300 6,364 Due after 10 years 180,868 — — Total fixed income securities $ 5,273,100 37,110 38,317
Schedule of Other Investment Portfolio by Strategy and the Remaining Commitment Amount Associated With Each Strategy	Other Investments December 31, 2018 December 31, 2017 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Carrying Value Remaining Maximum 1 Alternative Investments Private equity $ 84,352 93,688 178,040 52,251 99,026 151,277 Private credit 41,682 81,453 123,135 37,743 94,959 132,702 Real assets 27,862 27,129 54,991 25,379 27,014 52,393 Total alternative investments 153,896 202,270 356,166 115,373 220,999 336,372 Other securities 2 25,042 — 25,042 16,895 — 16,895 Total other investments $ 178,938 202,270 381,208 132,268 220,999 353,267
Schedule of Aggregated Summarized Balance Sheet Financial Information For Partnerships In Our Alternative Investment Portfolio	Balance Sheet Information September 30, ($ in millions) 2018 2017 Investments $ 28,292 21,046 Total assets 30,377 22,357 Total liabilities 4,532 4,767 Total partners’ capital 25,845 17,590
Schedule of Aggregated Summarized Income Statement Financial Information For Partnerships In Our Alternative Investment Portfolio	Income Statement Information 12 months ended September 30, ($ in millions) 2018 2017 2016 Net investment income (loss) $ 134 (143 ) (44 ) Realized gains 1,981 325 1,374 Net change in unrealized appreciation (depreciation) 1,303 2,894 (719 ) Net income $ 3,418 3,076 611 Insurance Subsidiaries' alternative investments income (loss) 17.6 12.7 3.1
Schedule Of Securities Pledged As Collateral	($ in millions) FHLBI Collateral FHLBNY Collateral State and Regulatory Deposits Total U.S. government and government agencies $ — — 22.5 22.5 Obligations of states and political subdivisions — — 3.9 3.9 Corporate securities — — 0.3 0.3 CMBS 7.2 18.1 — 25.3 RMBS 58.0 45.5 — 103.5 Total pledged as collateral $ 65.2 63.6 26.7 155.5
Schedule of Components of Pre-Tax Net Investment Income Earned	($ in thousands) 2018 2017 2016 Fixed income securities $ 178,104 153,230 129,306 Equity securities 7,764 6,442 7,368 Short-term investments 3,472 1,526 686 Other investments 17,799 12,871 2,940 Investment expenses (11,803 ) (12,187 ) (9,546 ) Net investment income earned $ 195,336 161,882 130,754
Schedule of OTTI by Asset Type	2018 Recognized in Earnings ($ in thousands) Gross Included in OCI AFS fixed income securities: Corporate securities $ 1,783 — 1,783 RMBS 2,903 — 2,903 Total AFS fixed income securities 4,686 — 4,686 Other investments 1,893 — 1,893 Total OTTI losses $ 6,579 — 6,579 2017 Recognized in Earnings ($ in thousands) Gross Included in OCI AFS fixed income securities: U.S. government and government agencies $ 36 — 36 Obligations of states and political subdivisons 612 — 612 Corporate securities 587 — 587 CLO and other ABS 96 — 96 CMBS 670 — 670 RMBS 1,183 (36 ) 1,219 Total AFS fixed income securities 3,184 (36 ) 3,220 AFS equity securities: Common stock 1,435 — 1,435 Total AFS equity securities 1,435 — 1,435 Other investments 190 — 190 Total OTTI losses $ 4,809 (36 ) 4,845 2016 Recognized in Earnings ($ in thousands) Gross Included in OCI AFS fixed income securities: Obligations of states and political subdivisons $ 2,797 — 2,797 CLO and other ABS 19 — 19 Corporate securities 1,880 — 1,880 CMBS 220 — 220 RMBS 275 10 265 Total AFS fixed income securities 5,191 10 5,181 AFS equity securities: Common stock 3,316 — 3,316 Preferred stock 2 — 2 Total AFS equity securities 3,318 — 3,318 Total OTTI losses $ 8,509 10 8,499
Components of Net Realized and Unrealized Gains (Losses)	($ in thousands) 2018 2017 2016 Net realized (losses) gains on the disposals of securities: Fixed income securities $ (34,953 ) 6,944 (3,668 ) Equity securities 18,695 4,629 7,244 Short-term investments (3 ) (4 ) (13 ) Other investments (2,714 ) (365 ) (1 ) Net realized (losses) gains on the disposal of securities (18,975 ) 11,204 3,562 OTTI charges (6,579 ) (4,845 ) (8,499 ) Net realized (losses) gains (25,554 ) 6,359 (4,937 ) Unrealized (losses) recognized in income on equity securities 1 (29,369 ) — — Total net realized and unrealized investment (losses) gains $ (54,923 ) 6,359 (4,937 ) 1 Includes unrealized holding gains (losses) of: (i) $(3.1) million on equity securities remaining in our portfolio as of December 31, 2018; and (ii) $(26.3) million on equity securities sold in 2018.
Schedule of Components of Net Realized Gains Excluding OTTI Charges	($ in thousands) 2018 2017 2016 HTM fixed income securities Gains $ 2 44 3 Losses — (1 ) (1 ) AFS fixed income securities Gains 5,460 10,193 7,741 Losses (40,415 ) (3,292 ) (11,411 ) Equity securities Gains 23,203 5,829 8,108 Losses (4,508 ) (1,200 ) (864 ) Short-term investments Gains 7 2 — Losses (10 ) (6 ) (13 ) Other investments Gains — 494 3 Losses (2,714 ) (859 ) (4 ) Total net realized investment (losses) gains $ (18,975 ) 11,204 3,562

Comprehensive Income (Tables)

Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2018
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Schedule of Components of Comprehensive Income-Gross and Net of Tax	2018 ($ in thousands) Gross Tax Net Net income $ 211,721 32,782 178,939 Components of OCI: Unrealized (losses) gains on investment securities : Unrealized holding losses during the year (123,145 ) (25,861 ) (97,284 ) Amounts reclassified into net income: HTM securities 110 23 87 Realized losses on AFS securities 39,641 8,325 31,316 Net unrealized losses (83,394 ) (17,513 ) (65,881 ) Defined benefit pension and post-retirement plans: Net actuarial loss (11,273 ) (2,367 ) (8,906 ) Amounts reclassified into net income: Net actuarial loss 2,127 447 1,680 Defined benefit pension and post-retirement plans (9,146 ) (1,920 ) (7,226 ) Other comprehensive loss (92,540 ) (19,433 ) (73,107 ) Comprehensive income $ 119,181 13,349 105,832 2017 ($ in thousands) Gross Tax Net Net income $ 261,968 93,142 168,826 Components of OCI: Unrealized gains (losses) on investment securities : Unrealized holding gains during the year 66,894 23,879 43,015 Non-credit portion of OTTI recognized in OCI 36 13 23 Amounts reclassified into net income: HTM securities (179 ) (63 ) (116 ) Non-credit OTTI 104 36 68 Realized gains on AFS securities (6,979 ) (2,442 ) (4,537 ) Net unrealized gains 59,876 21,423 38,453 Defined benefit pension and post-retirement plans: Net actuarial loss (4,684 ) (984 ) (3,700 ) Amounts reclassified into net income: Net actuarial loss 2,102 735 1,367 Defined benefit pension and post-retirement plans (2,582 ) (249 ) (2,333 ) Other comprehensive income 57,294 21,174 36,120 Comprehensive income $ 319,262 114,316 204,946 2016 ($ in thousands) Gross Tax Net Net income $ 219,955 61,460 158,495 Components of OCI: Unrealized (losses) gains on investment securities : Unrealized holding losses during the year (9,195 ) (3,218 ) (5,977 ) Non-credit portion of OTTI recognized in OCI (10 ) (4 ) (6 ) Amounts reclassified into net income: HTM securities (141 ) (49 ) (92 ) Non-credit OTTI 213 75 138 Realized losses on AFS securities 4,713 1,649 3,064 Net unrealized losses (4,420 ) (1,547 ) (2,873 ) Defined benefit pension and post-retirement plans: Net actuarial loss (12,079 ) (4,227 ) (7,852 ) Amounts reclassified into net income: Net actuarial loss 6,462 2,262 4,200 Defined benefit pension and post-retirement plans (5,617 ) (1,965 ) (3,652 ) Other comprehensive loss (10,037 ) (3,512 ) (6,525 ) Comprehensive income $ 209,918 57,948 151,970
Schedule of Components of Accumulated Other Comprehensive Income	Net Unrealized (Loss) Gain on Investment Securities Defined Benefit Pension and Post-retirement Plans ($ in thousands) OTTI Related HTM Related All Other Investments Subtotal Total AOCI Balance, December 31, 2016 $ (150 ) 102 42,170 42,122 (58,072 ) (15,950 ) OCI before reclassifications 23 — 43,015 43,038 (3,700 ) 39,338 Amounts reclassified from AOCI 68 (116 ) (4,537 ) (4,585 ) 1,367 (3,218 ) Net current period OCI 91 (116 ) 38,478 38,453 (2,333 ) 36,120 Balance, December 31, 2017 (59 ) (14 ) 80,648 80,575 (60,405 ) 20,170 Cumulative effect adjustments 1 (12 ) (2 ) (12,792 ) (12,806 ) (12,213 ) (25,019 ) Balance: December 31, 2017 as adjusted $ (71 ) (16 ) 67,856 67,769 (72,618 ) (4,849 ) OCI before reclassifications — — (97,284 ) (97,284 ) (8,906 ) (106,190 ) Amounts reclassified from AOCI — 87 31,316 31,403 1,680 33,083 Net current period OCI — 87 (65,968 ) (65,881 ) (7,226 ) (73,107 ) Balance, December 31, 2018 $ (71 ) 71 1,888 1,888 (79,844 ) (77,956 ) 1 Upon adoption of ASU 2016-01 and ASU 2018-02 in the first quarter of 2018, we recognized a $25.0 million cumulative-effect adjustment to the opening balance of AOCI, which represents the after-tax net unrealized gain on our equity portfolio as of December 31, 2017 and the one-time reclassification from AOCI to retained earnings for the stranded tax assets that were created in AOCI from the enactment of Tax Reform. See Note 3. "Adoption of Accounting Pronouncements" above for additional information.
Schedule of Reclassification out of Accumulated Other Comprehensive Income	($ in thousands) Year ended December 31, 2018 Year ended December 31, 2017 Affected Line Item in the Consolidated Statements of Income OTTI related Non-credit OTTI on disposed securities $ — 104 Net realized and unrealized (losses) gains — 104 Income before federal income tax — (36 ) Total federal income tax expense — 68 Net income HTM related Unrealized losses on HTM disposals 137 32 Net realized and unrealized (losses) gains Amortization of net unrealized gains on HTM securities (27 ) (211 ) Net investment income earned 110 (179 ) Income before federal income tax (23 ) 63 Total federal income tax expense 87 (116 ) Net income Realized losses (gains) on AFS Realized losses (gains) on AFS disposals 39,641 (6,979 ) Net realized and unrealized (losses) gains 39,641 (6,979 ) Income before federal income tax (8,325 ) 2,442 Total federal income tax expense 31,316 (4,537 ) Net income Defined benefit pension and post-retirement life plans Net actuarial loss 450 450 Loss and loss expense incurred 1,677 1,652 Other insurance expenses Total defined benefit pension and post-retirement life 2,127 2,102 Income before federal income tax (447 ) (735 ) Total federal income tax expense 1,680 1,367 Net income Total reclassifications for the period $ 33,083 (3,218 ) Net income

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Carrying Amounts and Estimated Fair Values of Financial Instruments	December 31, 2018 December 31, 2017 ($ in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial Assets Fixed income securities: HTM $ 37,110 38,317 42,129 44,100 AFS 5,273,100 5,273,100 5,162,522 5,162,522 Equity securities 147,639 147,639 182,705 182,705 Short-term investments 323,864 323,864 165,555 165,555 Long-term debt: 7.25% Senior Notes 49,907 57,032 49,904 61,391 6.70% Senior Notes 99,462 107,075 99,446 116,597 5.875% Senior Notes 185,000 177,230 185,000 186,332 1.61% Borrowings from FHLBNY 25,000 24,218 25,000 24,270 1.56% Borrowings from FHLBNY 25,000 24,162 25,000 24,210 3.03% Borrowings from FHLBI 60,000 58,905 60,000 60,334 Subtotal long-term debt 444,369 448,622 444,350 473,134 Unamortized debt issuance costs (4,829 ) (5,234 ) Total long-term debt $ 439,540 439,116
Schedule of Quantitative Disclosures of our Financial Assets that were Measured at Fair Value	December 31, 2018 Fair Value Measurements Using ($ in thousands) Assets Measured at Fair Value Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) 1 Significant Other Observable Inputs (Level 2) 1 Significant Unobservable Inputs (Level 3) Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 121,310 78,381 42,929 — Foreign government 23,131 — 23,131 — Obligations of states and political subdivisions 1,138,469 — 1,138,469 — Corporate securities 1,617,408 — 1,617,408 — CLO and other ABS 717,362 — 709,953 7,409 CMBS 527,078 — 527,078 — RMBS 1,128,342 — 1,128,342 — Total AFS fixed income securities 5,273,100 78,381 5,187,310 7,409 Equity securities: Common stock 2 144,727 107,397 — — Preferred stock 2,912 2,912 — — Total equity securities 147,639 110,309 — — Short-term investments 323,864 321,370 2,494 — Total assets measured at fair value $ 5,744,603 510,060 5,189,804 7,409 December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets Measured at Fair Value Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) 1 Significant Other Observable Inputs (Level 2) 1 Significant Unobservable Inputs (Level 3) Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 49,740 24,652 25,088 — Foreign government 18,555 — 18,555 — Obligations of states and political subdivisions 1,582,970 — 1,582,970 — Corporate securities 1,617,468 — 1,617,468 — CLO and other ABS 795,458 — 795,458 — CMBS 383,449 — 376,895 6,554 RMBS 714,882 — 714,882 — Total AFS fixed income securities 5,162,522 24,652 5,131,316 6,554 AFS equity securities: Common stock 167,757 138,640 — 5,398 Preferred stock 14,948 14,948 — — Total AFS equity securities 182,705 153,588 — 5,398 Total AFS securities 5,345,227 178,240 5,131,316 11,952 Short-term investments 165,555 165,555 — — Total assets measured at fair value $ 5,510,782 343,795 5,131,316 11,952 1 There were no transfers of securities between Level 1 and Level 2. 2 In accordance with ASU 2015-07, investments amounting to $37.3 million and $23.7 million at December 31, 2018 and December 31, 2017, respectively, were measured at fair value using the net asset value per share (or its practical expedient) and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to total assets measured at fair value.
Schedule of Summary of the Changes in Fair Value of Securities Using Level 3 Inputs	2018 ($ in thousands) CMBS CLO and Other ABS Common Stock Total Fair value, December 31, 2017 $ 6,554 — 5,398 11,952 Total net (losses) gains for the period included in: OCI — — — — Net income — — — — Purchases — 7,409 — 7,409 Sales — — — — Issuances — — — — Settlements — — — — Transfers into Level 3 — — — — Transfers out of Level 3 (6,554 ) — (5,398 ) (11,952 ) Fair value, December 31, 2018 $ — 7,409 — 7,409
Schedule of Quantitative Information of our Financial Assets and Liabilities that were Disclosed at Fair Value	December 31, 2018 Fair Value Measurements Using ($ in thousands) Assets/Liabilities Disclosed at Fair Value Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets HTM: Obligations of states and political subdivisions $ 17,969 — 17,969 — Corporate securities 20,348 — 20,348 — Total HTM fixed income securities $ 38,317 — 38,317 — Financial Liabilities Long-term debt: 7.25% Senior Notes $ 57,032 — 57,032 — 6.70% Senior Notes 107,075 — 107,075 — 5.875% Senior Notes 177,230 177,230 — — 1.61% Borrowings from FHLBNY 24,218 — 24,218 — 1.56% Borrowings from FHLBNY 24,162 — 24,162 — 3.03% Borrowings from FHLBI 58,905 — 58,905 — Total long-term debt $ 448,622 177,230 271,392 — December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets/Liabilities Disclosed at Fair Value Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets HTM: Obligations of states and political subdivisions $ 26,261 — 26,261 — Corporate securities 17,839 — 12,306 5,533 Total HTM fixed income securities $ 44,100 — 38,567 5,533 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 61,391 — 61,391 — 6.70% Senior Notes 116,597 — 116,597 — 5.875% Senior Notes 186,332 186,332 — — 1.61% Borrowings from FHLBNY 24,270 — 24,270 — 1.56% Borrowings from FHLBNY 24,210 — 24,210 — 3.03% Borrowings from FHLBI 60,334 — 60,334 — Total long-term debt $ 473,134 186,332 286,802 —

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2018
Reinsurance Disclosures [Abstract]
Schedule of Total Reinsurance Balances Segregated By Reinsurer	As of December 31, 2018 As of December 31, 2017 ($ in thousands) Reinsurance Balances % of Reinsurance Balance Reinsurance Balances % of Reinsurance Balance Total reinsurance recoverables $ 549,172 $ 594,832 Total prepaid reinsurance premiums 157,723 153,493 Total reinsurance balance 706,895 748,325 Federal and state pools 1 : NFIP 170,453 24 % 204,161 27 % New Jersey Unsatisfied Claim Judgment Fund 55,167 7 62,947 9 Other 3,602 1 3,634 — Total federal and state pools 229,222 32 270,742 36 Remaining reinsurance balance $ 477,673 68 $ 477,583 64 Munich Re Group (A.M. Best rated "A+") $ 112,841 16 $ 117,460 16 Hannover Ruckversicherungs AG (A.M. Best rated "A+") 101,835 14 101,652 14 AXIS Reinsurance Company (A.M. Best rated "A+") 69,102 10 62,396 8 Swiss Re Group (A.M. Best rated "A+") 37,519 5 40,772 5 Transatlantic Reinsurance Company (A.M. Best rated “A+”) 17,686 3 13,237 2 Endurance Specialty Ins. LTD. (A.M. Best rated “A+”) 15,163 2 18,469 2 Partner Reinsurance Company of the U.S. (A.M. Best rated “A”) 12,261 2 16,925 2 All other reinsurers 111,266 16 106,672 15 Total reinsurers 477,673 68 % 477,583 64 % Less: collateral 2 (112,201 ) (122,413 ) Reinsurers, net of collateral $ 365,472 $ 355,170 1 Considered to have minimal risk of default. 2 Includes letters of credit, trust funds, and funds held against reinsurance recoverables.
List Of Direct, Assumed, And Ceded Reinsurance Amounts	($ in thousands) 2018 2017 2016 Premiums written: Direct $ 2,890,633 2,733,459 2,577,259 Assumed 26,250 26,685 28,779 Ceded (402,597 ) (389,503 ) (368,750 ) Net $ 2,514,286 2,370,641 2,237,288 Premiums earned: Direct $ 2,808,764 2,647,488 2,484,715 Assumed 25,831 25,831 28,214 Ceded (398,366 ) (382,292 ) (363,357 ) Net $ 2,436,229 2,291,027 2,149,572 Loss and loss expense incurred: Direct $ 1,706,951 1,570,678 1,560,356 Assumed 21,469 17,588 22,708 Ceded (230,286 ) (243,192 ) (348,267 ) Net $ 1,498,134 1,345,074 1,234,797
Schedule of Ceded Premiums and Losses Related to Flood Operations	Ceded to NFIP ($ in thousands) 2018 2017 2016 Ceded premiums written $ (248,053 ) (241,345 ) (232,245 ) Ceded premiums earned (244,238 ) (235,088 ) (227,882 ) Ceded loss and loss expense incurred (144,967 ) (160,922 ) (239,891 )

Reserve for Loss and Loss Exp_2

Reserve for Loss and Loss Expense (Tables)	12 Months Ended
	Dec. 31, 2018
Insurance Loss Reserves [Abstract]
Schedule of Roll Forward of Reserve for Loss and Loss Expense	($ in thousands) 2018 2017 2016 Gross reserves for loss and loss expense, at beginning of year $ 3,771,240 3,691,719 3,517,728 Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of year 585,855 611,200 551,019 Net reserves for loss and loss expense, at beginning of year 3,185,385 3,080,519 2,966,709 Incurred loss and loss expense for claims occurring in the: Current year 1,527,997 1,384,266 1,300,565 Prior years (29,863 ) (39,192 ) (65,768 ) Total incurred loss and loss expense 1,498,134 1,345,074 1,234,797 Paid loss and loss expense for claims occurring in the: Current year 573,718 497,486 450,811 Prior years 753,321 742,722 670,176 Total paid loss and loss expense 1,327,039 1,240,208 1,120,987 Net reserves for loss and loss expense, at end of year 3,356,480 3,185,385 3,080,519 Add: Reinsurance recoverable on unpaid loss and loss expense, at end of year 537,388 585,855 611,200 Gross reserves for loss and loss expense at end of year $ 3,893,868 3,771,240 3,691,719
Schedule of (Favorable)/ Unfavorable Prior Year Development	(Favorable)/Unfavorable Prior Year Development ($ in millions) 2018 2017 2016 General Liability $ (9.5 ) (48.3 ) (45.0 ) Commercial Automobile 36.7 35.6 25.3 Workers Compensation (83.0 ) (52.3 ) (56.0 ) Businessowners' Policies (1.5 ) 1.9 1.8 Commercial Property 7.5 8.7 0.3 Homeowners 9.8 0.4 1.7 Personal Automobile 3.0 6.7 1.0 E&S Casualty Lines 12.0 10.0 6.0 E&S Property Lines (4.8 ) 0.1 1.2 Other (0.1 ) (2.0 ) (2.1 ) Total $ (29.9 ) (39.2 ) (65.8 )
Schedule of Exposure to Various Asbestos and Environmental Claims	2018 ($ in millions) Gross Net Asbestos $ 7.3 6.1 Landfill sites 12.2 7.4 Underground storage tanks 10.5 9.3 Total $ 30.0 22.8
Schedule of Roll Forward of Gross and Net Asbestos and Environmental Incurred Losses and Loss Expenses and Related Reserves	2018 2017 2016 ($ in thousands) Gross Net Gross Net Gross Net Asbestos Reserves for loss and loss expense at beginning of year $ 7,577 6,346 7,847 6,615 8,024 6,793 Incurred loss and loss expense — — — — 77 77 Less: loss and loss expense paid (249 ) (249 ) (270 ) (269 ) (254 ) (255 ) Reserves for loss and loss expense at the end of year $ 7,328 6,097 7,577 6,346 7,847 6,615 Environmental Reserves for loss and loss expense at beginning of year $ 20,838 14,866 22,115 16,101 22,387 16,368 Incurred loss and loss expense 3,059 2,877 126 — 1,406 1,303 Less: loss and loss expense paid (1,205 ) (1,057 ) (1,403 ) (1,235 ) (1,678 ) (1,570 ) Reserves for loss and loss expense at the end of year $ 22,692 16,686 20,838 14,866 22,115 16,101 Total Asbestos and Environmental Claims Reserves for loss and loss expense at beginning of year $ 28,415 21,212 29,962 22,716 30,411 23,161 Incurred loss and loss expense 3,059 2,877 126 — 1,483 1,380 Less: loss and loss expense paid (1,454 ) (1,306 ) (1,673 ) (1,504 ) (1,932 ) (1,825 ) Reserves for loss and loss expense at the end of year $ 30,020 22,783 28,415 21,212 29,962 22,716
Schedule of Short-duration Insurance Contracts, Claims Development	All Lines (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 920,143 941,972 916,691 883,590 870,057 869,927 857,960 853,401 848,413 846,017 34,771 85,707 2010 950,114 973,742 977,959 956,600 943,118 922,404 915,131 907,074 904,561 42,224 94,400 2011 1,042,576 1,061,667 1,062,233 1,056,107 1,033,518 1,023,726 1,019,351 1,013,115 50,251 104,677 2012 1,065,437 1,071,290 1,020,655 998,028 973,089 973,644 973,411 66,071 103,949 2013 1,044,142 1,062,045 1,047,230 1,021,007 1,002,316 987,763 86,250 91,084 2014 1,107,513 1,133,798 1,146,990 1,124,014 1,104,218 117,760 94,774 2015 1,114,081 1,130,513 1,144,830 1,138,313 175,271 93,673 2016 1,188,608 1,203,634 1,227,142 319,825 93,724 2017 1,270,110 1,313,372 471,978 96,426 2018 1,413,800 677,444 96,408 Total 10,921,712 All Lines (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 277,275 442,417 540,982 634,902 695,249 736,100 760,589 775,885 784,713 791,281 2010 328,826 509,910 625,229 704,895 773,536 803,773 823,770 835,532 846,386 2011 391,944 585,867 692,730 782,655 852,202 901,801 924,111 940,626 2012 378,067 555,819 651,544 743,742 810,135 856,195 879,372 2013 335,956 518,872 644,475 748,758 833,823 872,331 2014 405,898 614,075 736,154 855,959 936,425 2015 376,641 581,203 725,385 845,868 2016 387,272 617,958 764,331 2017 433,440 678,453 2018 511,271 Total 8,066,344 All outstanding liabilities before 2009, net of reinsurance 361,631 Liabilities for loss and loss expenses, net of reinsurance 3,216,999 General Liability (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 237,913 241,625 233,530 223,146 212,947 211,243 206,387 205,741 201,568 203,176 15,951 13,873 2010 215,208 228,680 242,499 237,154 222,328 211,619 208,968 202,394 206,146 18,634 12,696 2011 227,769 228,720 239,480 230,785 217,256 211,196 212,011 211,500 20,973 11,614 2012 238,979 245,561 215,083 194,144 175,305 175,268 180,659 25,251 9,960 2013 250,609 251,421 239,776 225,709 210,785 203,831 35,971 10,326 2014 244,312 249,946 257,132 239,333 234,082 57,041 10,513 2015 254,720 245,710 246,990 233,249 84,861 10,253 2016 277,214 272,048 277,986 142,991 10,213 2017 293,747 293,128 202,925 10,032 2018 317,934 270,267 8,741 Total 2,361,691 General Liability (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 14,346 37,143 64,970 103,213 130,554 151,920 166,767 176,316 180,621 183,263 2010 15,726 46,201 80,018 113,050 143,360 161,487 172,394 178,179 183,988 2011 13,924 42,692 73,643 102,978 135,377 159,768 170,525 181,856 2012 13,030 35,241 56,580 89,008 109,448 130,866 144,451 2013 12,789 35,113 72,127 104,587 139,114 153,628 2014 14,901 46,825 79,972 121,969 154,957 2015 14,665 39,978 78,668 116,804 2016 15,684 46,549 89,431 2017 17,366 49,470 2018 19,531 Total 1,277,379 All outstanding liabilities before 2009, net of reinsurance 90,918 Liabilities for loss and loss expenses, net of reinsurance 1,175,230 Workers Compensation (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 197,504 215,946 213,036 210,109 210,756 216,992 212,536 208,611 208,142 205,125 18,242 12,218 2010 198,371 214,469 212,815 211,030 214,916 212,448 208,155 204,423 199,539 22,614 12,185 2011 205,238 218,973 214,743 215,114 210,591 205,708 200,674 194,821 26,226 11,850 2012 203,864 208,036 199,360 195,197 188,596 187,359 183,314 30,444 11,613 2013 199,794 194,318 187,658 173,160 166,662 162,787 30,648 11,372 2014 199,346 187,065 182,579 172,515 164,420 33,422 10,488 2015 193,729 194,639 183,604 179,642 34,940 10,544 2016 196,774 184,946 176,248 56,258 10,553 2017 195,202 184,306 72,213 10,745 2018 193,894 98,015 10,553 Total 1,844,096 Workers Compensation (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 37,885 87,299 117,019 133,116 145,417 154,726 160,529 164,336 167,894 171,205 2010 46,795 93,281 122,442 137,184 149,086 153,795 158,078 162,796 165,526 2011 42,941 90,836 118,847 134,646 139,232 149,269 154,320 158,535 2012 40,911 86,909 108,211 122,755 132,052 139,477 143,281 2013 36,829 74,568 96,376 109,739 118,669 124,130 2014 35,924 78,944 100,876 113,626 119,392 2015 33,857 77,320 98,195 112,601 2016 34,525 78,531 98,037 2017 40,375 82,216 2018 41,122 Total 1,216,045 All outstanding liabilities before 2009, net of reinsurance 245,831 Liabilities for loss and loss expenses, net of reinsurance 873,882 Commercial Automobile (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 199,541 191,079 182,724 169,858 166,682 162,911 161,251 161,923 161,300 161,057 574 24,749 2010 187,562 189,305 187,778 181,923 179,854 172,969 173,157 173,471 173,080 762 25,406 2011 174,006 183,044 182,325 178,421 172,617 174,882 174,514 173,507 1,633 25,398 2012 179,551 191,947 183,527 184,289 184,367 186,128 184,633 2,259 24,025 2013 188,289 205,282 209,197 207,994 210,410 207,975 3,756 25,556 2014 200,534 212,725 216,824 219,925 218,172 8,718 27,528 2015 220,994 240,958 253,074 259,495 19,192 29,092 2016 255,187 274,367 285,302 46,407 30,855 2017 301,274 329,389 98,125 32,122 2018 347,908 164,906 32,895 Total 2,340,518 Commercial Automobile (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 63,126 94,406 113,697 137,564 149,949 155,560 158,303 159,723 160,013 160,456 2010 68,098 99,254 128,015 146,913 163,513 167,227 169,100 169,793 171,693 2011 69,849 99,196 121,576 142,507 157,291 166,082 170,000 170,913 2012 73,316 105,371 127,235 148,669 168,114 176,656 179,501 2013 76,469 109,893 140,015 169,850 189,626 200,750 2014 80,810 117,169 148,884 180,701 202,821 2015 91,347 132,260 175,866 211,515 2016 106,022 155,720 200,701 2017 117,287 178,823 2018 134,867 Total 1,812,040 All outstanding liabilities before 2009, net of reinsurance 3,842 Liabilities for loss and loss expenses, net of reinsurance 532,320 Businessowners' Policies (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 48,535 51,762 46,645 43,828 43,553 44,938 44,299 44,273 43,933 44,028 323 3,474 2010 53,669 49,285 42,408 39,915 40,899 40,581 41,239 41,197 40,920 381 3,918 2011 54,469 57,083 51,047 58,242 59,256 58,966 58,456 58,735 1,140 4,959 2012 54,342 48,029 46,303 44,172 44,077 43,747 43,418 430 5,542 2013 49,617 42,618 41,005 40,624 41,369 39,709 1,404 3,482 2014 55,962 60,949 62,548 59,806 58,517 2,959 4,062 2015 52,871 53,768 57,245 55,925 6,215 3,952 2016 52,335 53,792 54,993 9,272 3,823 2017 46,624 48,698 13,087 3,808 2018 55,024 16,177 3,823 Total 499,967 Businessowners' Policies (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 18,915 29,612 32,689 36,073 40,052 42,895 43,358 43,448 43,547 43,596 2010 20,821 28,131 31,027 34,705 37,819 38,900 40,279 40,395 40,439 2011 27,884 37,362 41,011 46,444 52,114 55,856 57,045 57,365 2012 22,199 31,833 35,089 37,215 38,766 40,627 41,326 2013 17,412 26,592 30,845 34,760 37,993 38,464 2014 28,914 40,584 44,911 49,460 52,940 2015 24,189 36,014 42,710 46,571 2016 24,655 36,848 39,973 2017 21,865 31,337 2018 29,995 Total 422,006 All outstanding liabilities before 2009, net of reinsurance 7,783 Liabilities for loss and loss expenses, net of reinsurance 85,744 Commercial Property (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 82,619 82,124 82,025 82,014 80,774 80,455 80,558 80,545 80,416 80,410 2 7,009 2010 105,647 96,851 97,386 96,127 95,530 95,363 95,178 95,155 95,142 4 7,668 2011 136,954 131,667 130,942 131,282 131,353 131,113 131,049 131,009 6 9,038 2012 118,464 114,224 115,375 116,658 117,102 117,170 117,225 21 8,515 2013 88,101 90,639 90,103 90,005 90,436 90,278 28 5,713 2014 141,192 136,249 136,820 138,751 138,155 57 6,514 2015 110,270 109,513 111,750 111,566 77 6,401 2016 121,927 126,185 125,937 405 6,727 2017 138,773 149,106 (76 ) 6,850 2018 183,177 7,052 7,695 Total 1,222,005 Commercial Property (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 59,933 78,695 80,433 80,894 80,251 80,352 80,529 80,509 80,405 80,393 2010 69,543 91,918 94,602 95,111 95,270 95,147 95,156 95,150 95,138 2011 94,538 127,580 129,579 130,681 131,060 131,115 131,089 131,100 2012 81,528 108,834 111,503 114,699 116,291 116,625 116,671 2013 60,244 87,874 90,446 90,350 90,840 90,696 2014 101,131 132,909 136,634 137,883 137,418 2015 79,048 106,182 109,829 110,994 2016 83,966 118,789 122,930 2017 99,047 142,338 2018 135,416 Total 1,163,094 All outstanding liabilities before 2009, net of reinsurance 69 Liabilities for loss and loss expenses, net of reinsurance 58,980 Personal Automobile (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 93,808 103,319 105,033 103,908 104,734 103,866 103,393 103,412 103,348 103,303 146 17,346 2010 103,340 110,075 112,346 109,515 107,490 107,405 107,224 107,054 106,887 160 20,822 2011 113,232 116,164 113,686 112,993 114,241 113,830 113,988 113,921 194 22,700 2012 113,771 114,921 109,832 109,324 110,294 110,300 109,795 205 22,332 2013 108,417 109,620 106,225 106,703 107,759 107,680 288 22,373 2014 102,250 109,325 106,757 107,452 106,821 774 22,504 2015 96,387 99,698 100,214 99,570 2,572 20,860 2016 92,727 98,032 100,202 6,252 19,803 2017 101,880 105,139 13,162 20,679 2018 111,594 23,506 21,748 Total 1,064,912 Personal Automobile (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 51,039 71,911 86,431 96,229 100,566 102,187 102,322 102,437 103,009 103,010 2010 58,786 82,490 95,300 101,540 104,061 105,849 106,453 106,733 106,722 2011 61,323 82,102 93,878 105,068 111,085 112,732 113,551 113,664 2012 63,704 82,729 94,842 102,977 107,890 109,355 109,447 2013 61,384 80,861 92,637 100,528 105,131 106,679 2014 62,519 83,739 92,589 99,173 104,055 2015 58,725 76,470 87,163 92,102 2016 57,961 76,823 86,752 2017 62,854 82,730 2018 69,721 Total 974,882 All outstanding liabilities before 2009, net of reinsurance 6,040 Liabilities for loss and loss expenses, net of reinsurance 96,070 Homeowners (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 47,636 44,511 42,609 40,313 61,927 40,400 40,465 40,457 40,451 40,500 70 5,634 2010 68,373 67,525 63,285 97,761 62,462 62,402 62,339 62,392 62,402 83 9,132 2011 103,804 98,211 82,744 94,167 94,543 94,183 94,378 94,587 131 15,109 2012 87,260 82,745 86,560 86,667 86,271 86,330 86,483 237 16,939 2013 73,670 72,528 71,494 72,145 71,714 72,148 331 7,747 2014 80,111 82,461 83,637 83,844 83,539 411 8,770 2015 76,637 76,400 76,559 74,723 1,172 7,744 2016 60,105 60,931 62,391 1,837 6,869 2017 59,167 67,978 1,969 7,299 2018 62,961 6,660 7,062 Total 707,712 Homeowners (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 28,299 36,965 38,078 39,342 39,731 39,819 39,907 40,189 40,269 40,403 2010 43,699 58,638 60,295 61,106 62,155 62,227 62,241 62,272 62,283 2011 71,668 89,963 91,718 92,185 93,312 93,720 94,007 94,412 2012 69,056 79,584 82,720 84,250 85,196 85,562 85,642 2013 50,664 65,528 67,838 69,775 71,776 72,197 2014 61,561 76,007 79,751 81,664 82,583 2015 52,589 70,078 72,202 72,927 2016 42,252 57,333 59,546 2017 45,466 63,290 2018 49,430 Total 682,713 All outstanding liabilities before 2009, net of reinsurance 6,107 Liabilities for loss and loss expenses, net of reinsurance 31,106 E&S Casualty Lines (in thousands, except for claim counts) Incurred Loss and Allocated Loss Expenses, Net of Reinsurance As of Accident Year Unaudited IBNR Cumulative Number of Reported Claims 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ 885 1,053 938 728 710 96 737 739 — 274 2010 3,294 4,106 3,369 4,299 3,831 3,055 4,932 5,168 — 813 2011 8,127 7,102 9,853 12,207 10,273 9,652 10,228 12,119 276 1,321 2012 42,367 42,621 43,175 46,149 46,165 45,988 46,444 6,417 2,022 2013 55,468 60,309 67,099 69,112 67,647 68,972 14,175 2,266 2014 55,316 63,505 69,929 71,719 71,206 14,097 2,040 2015 75,498 76,432 82,404 90,488 24,516 2,746 2016 94,451 96,416 104,655 52,151 2,732 2017 91,438 95,783 66,321 2,353 2018 98,324 82,486 1,734 Total 593,898 E&S Casualty Lines (in thousands) Cumulative Paid Loss and Allocated Loss Expenses, Net of Reinsurance Accident Year Unaudited 2011 2012 2013 2014 2015 2016 2017 2018 2009 $ — 198 431 605 626 709 737 739 2010 — 1,218 2,570 3,574 4,078 4,513 4,610 4,908 2011 — 806 3,200 6,445 9,954 9,912 10,256 9,819 2012 3,722 7,914 16,430 25,064 32,343 36,278 38,298 2013 2,715 9,470 21,980 35,200 46,108 51,142 2014 2,353 12,234 25,571 43,877 53,780 2015 3,036 13,057 29,389 50,712 2016 3,720 16,195 33,950 2017 5,057 14,672 2018 5,509 Total 263,529 All outstanding liabilities before 2009, net of reinsurance 98 Liabilities for loss and loss expenses, net of reinsurance 330,467
Schedule of Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability	(in thousands) December 31, 2018 Net outstanding liabilities: Standard Commercial Lines General liability $ 1,175,230 Workers compensation 873,882 Commercial automobile 532,320 Businessowners' policies 85,744 Commercial property 58,980 Other Standard Commercial Lines 9,122 Total Standard Commercial Lines net outstanding liabilities 2,735,278 Standard Personal Lines Personal automobile 96,070 Homeowners 31,106 Other Standard Personal Lines 10,474 Total Standard Personal Lines net outstanding liabilities 137,650 E&S Lines Casualty lines 330,467 Property lines 13,604 Total E&S Lines net outstanding liabilities 344,071 Total liabilities for unpaid loss and loss expenses, net of reinsurance 3,216,999 Reinsurance recoverable on unpaid claims: Standard Commercial Lines General liability 181,102 Workers compensation 220,683 Commercial automobile 15,641 Businessowners' policies 3,473 Commercial property 12,620 Other Standard Commercial Lines 2,909 Total Standard Commercial Lines reinsurance recoverable on unpaid loss 436,428 Standard Personal Lines Personal automobile 45,572 Homeowners 1,346 Other Standard Personal Lines 31,777 Total Standard Personal Lines reinsurance recoverable on unpaid loss 78,695 E&S Lines Casualty lines 21,898 Property lines 367 Total E&S Lines reinsurance recoverable on unpaid loss 22,265 Total reinsurance recoverable on unpaid loss 537,388 Unallocated loss expenses 139,481 Total gross liability for unpaid loss and loss expenses $ 3,893,868
Schedule of Short-duration Insurance Contracts, Schedule of Historical Claims Duration	Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 General liability 6.5% 12.2 15.3 17.0 14.5 9.8 6.3 4.8 2.7 1.1 Workers compensation 21.2 24.3 13.2 8.3 5.4 3.9 2.4 2.3 1.4 1.1 Commercial automobile 37.9 17.3 14.5 13.1 9.5 4.0 1.6 0.8 0.7 0.4 Businessowners’ policies 47.3 19.9 8.3 8.3 7.4 4.3 1.7 0.5 0.2 1.1 Commercial property 70.7 25.2 2.7 1.1 0.2 0.1 — — — — Personal automobile 57.1 18.5 10.5 7.2 4.3 1.5 0.4 0.1 0.2 — Homeowners 72.3 20.3 3.1 1.8 1.4 0.4 0.2 0.1 0.1 0.1 E&S Lines - casualty 5.0 11.4 17.1 21.4 15.4 8.6 5.4

Indebtedness (Tables)

Indebtedness (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Outstanding Debt 1 2018 Carry Value ($ in thousands) Issuance Date Maturity Date Interest Rate Original Amount Debt Discount and Unamortized Issuance Costs December 31, 2018 December 31, 2017 Description Long-term: (1) FHLBI 12/16/2016 12/16/2026 3.03 % $ 60,000 — 60,000 60,000 (2) FHLBNY 8/15/2016 8/16/2021 1.56 % 25,000 — 25,000 25,000 (2) FHLBNY 7/21/2016 7/21/2021 1.61 % 25,000 — 25,000 25,000 (3) Senior Notes 2/8/2013 2/9/2043 5.875 % 185,000 (4,229 ) 180,771 180,430 (4) Senior Notes 11/3/2005 11/1/2035 6.70 % 100,000 (931 ) 99,069 99,011 (5) Senior Notes 11/16/2004 11/15/2034 7.25 % 50,000 (300 ) 49,700 49,675 Total long-term debt $ 445,000 (5,460 ) 439,540 439,116

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Revenue from Continuing Operations By Segment	Revenue by Segment Years ended December 31, ($ in thousands) 2018 2017 2016 Standard Commercial Lines: Net premiums earned: Commercial automobile $ 493,093 442,818 398,942 Workers compensation 317,616 317,982 308,233 General liability 616,187 569,217 527,859 Commercial property 329,660 311,932 293,438 Businessowners’ policies 103,412 100,266 97,754 Bonds 33,991 29,086 23,227 Other 18,263 17,198 16,030 Miscellaneous income 8,180 9,488 7,782 Total Standard Commercial Lines revenue 1,920,402 1,797,987 1,673,265 Standard Personal Lines: Net premiums earned: Personal automobile 168,250 153,147 142,876 Homeowners 128,961 129,699 130,973 Other 7,230 6,855 6,758 Miscellaneous income 1,257 1,228 1,098 Total Standard Personal Lines revenue 305,698 290,929 281,705 E&S Lines: Net premiums earned: Casualty lines 164,313 157,366 151,638 Property lines 55,253 55,461 51,844 Miscellaneous income 1 — 1 Total E&S Lines revenue 219,567 212,827 203,483 Investments: Net investment income 195,336 161,882 130,754 Net realized and unrealized investment (losses) gains (54,923 ) 6,359 (4,937 ) Total Investments revenues 140,413 168,241 125,817 Total revenues $ 2,586,080 2,469,984 2,284,270
Schedule of Income from Continuing Operations before and after Federal Income Tax	Income Before and After Federal Income Tax Years ended December 31, ($ in thousands) 2018 2017 2016 Standard Commercial Lines: Underwriting gain, before federal income tax $ 109,104 149,514 146,435 Underwriting gain, after federal income tax 86,192 97,184 95,183 Combined ratio 94.3 % 91.6 % 91.2 % ROE contribution 4.9 % 6.1 6.4 Standard Personal Lines: Underwriting gain, before federal income tax 12,764 11,104 12,419 Underwriting gain, after federal income tax 10,084 7,217 8,072 Combined ratio 95.8 % 96.2 % 95.6 % ROE contribution 0.6 % 0.4 0.6 E&S Lines: Underwriting loss, before federal income tax (695 ) (6,282 ) (6,921 ) Underwriting loss, after federal income tax (549 ) (4,083 ) (4,499 ) Combined ratio 100.3 % 103.0 % 103.4 % ROE contribution — % (0.3 ) (0.3 ) Investments: Net investment income $ 195,336 161,882 130,754 Net realized and unrealized investment (losses) gains (54,923 ) 6,359 (4,937 ) Total investment income, before federal income tax 140,413 168,241 125,817 Tax on investment income 19,560 45,588 30,621 Total investment income, after federal income tax $ 120,853 122,653 95,196 ROE contribution of after-tax net investment income 6.9 % 7.5 6.5
Schedule of Reconciliation of Segment Results to Income From Continuing Operations, Before Federal Income Tax	Reconciliation of Segment Results to Income Before Federal Income Tax Years ended December 31, ($ in thousands) 2018 2017 2016 Underwriting gain (loss) Standard Commercial Lines $ 109,104 149,514 146,435 Standard Personal Lines 12,764 11,104 12,419 E&S Lines (695 ) (6,282 ) (6,921 ) Investment income 140,413 168,241 125,817 Total all segments 261,586 322,577 277,750 Interest expense (24,419 ) (24,354 ) (22,771 ) Corporate expenses (25,446 ) (36,255 ) (35,024 ) Income, before federal income tax $ 211,721 261,968 219,955

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Reconciliation of Earnings Per Share	2018 Income Shares Per Share ($ in thousands, except per share amounts) (Numerator) (Denominator) Amount Basic EPS: Net income available to common stockholders $ 178,939 58,950 $ 3.04 Effect of dilutive securities: Stock compensation plans — 763 Diluted EPS: Net income available to common stockholders $ 178,939 59,713 $ 3.00 2017 Income Shares Per Share ($ in thousands, except per share amounts) (Numerator) (Denominator) Amount Basic EPS: Net income available to common stockholders $ 168,826 58,458 $ 2.89 Effect of dilutive securities: Stock compensation plans — 899 Diluted EPS: Net income available to common stockholders $ 168,826 59,357 $ 2.84 2016 Income Shares Per Share ($ in thousands, except per share amounts) (Numerator) (Denominator) Amount Basic EPS: Net income available to common stockholders $ 158,495 57,889 $ 2.74 Effect of dilutive securities: Stock compensation plans — 858 Diluted EPS: Net income available to common stockholders $ 158,495 58,747 $ 2.70

Federal Income Taxes (Tables)

Federal Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of Federal Income Tax on Income at the Corporate Rate to the Effective Tax Rate	($ in thousands) 2018 2017 2016 Tax at statutory rate (21% in 2018 and 35% in 2017 and 2016) $ 44,461 91,689 76,984 Tax-advantaged interest (5,518 ) (11,510 ) (12,126 ) Dividends received deduction (647 ) (1,961 ) (1,114 ) Executive compensation 2,279 — 121 Stock-based compensation (3,093 ) (4,281 ) — Tax Reform deferred tax write off — 20,205 — Other 1 (4,700 ) (1,000 ) (2,405 ) Federal income tax expense from continuing operations $ 32,782 93,142 61,460
Schedule of Deferred Tax Assets and Liabilities	($ in thousands) 2018 2017 Deferred tax assets: Net loss reserve discounting $ 43,285 38,771 Net unearned premiums 53,556 50,267 Employee benefits 8,862 8,606 Long-term incentive compensation plans 9,095 12,221 Temporary investment write-downs 1,155 1,044 Net operating loss — 54 Other 5,744 5,784 Total deferred tax assets 121,697 116,747 Deferred tax liabilities: Deferred policy acquisition costs 53,049 47,484 Unrealized gains on investment securities 502 26,183 Other investment-related items, net 4,904 2,500 Accelerated depreciation and amortization 9,702 8,590 Total deferred tax liabilities 68,157 84,757 Net deferred federal income tax asset $ 53,540 31,990

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Schedule of Funded Status Of Retirement Income Plan And Retirement Life Plan	December 31, Pension Plan ($ in thousands) 2018 2017 Change in Benefit Obligation: Benefit obligation, beginning of year $ 364,411 330,588 Service cost — — Interest cost 12,428 12,490 Actuarial (gains) losses (31,738 ) 31,158 Benefits paid (10,422 ) (9,825 ) Benefit obligation, end of year $ 334,679 364,411 Change in Fair Value of Assets: Fair value of assets, beginning of year $ 363,673 316,515 Actual return on plan assets, net of expenses (21,571 ) 46,983 Contributions by the employer to funded plans — 10,000 Benefits paid (10,422 ) (9,825 ) Fair value of assets, end of year $ 331,680 363,673 Funded status $ (2,999 ) (738 )
Schedule of Amounts Recognized in Consolidated Balance Sheet	Amounts Recognized in the Consolidated Balance Sheet: Liabilities $ (2,999 ) (738 ) Net pension liability, end of year $ (2,999 ) (738 )
Schedule of Amounts recognized in Accumulated Other than Comprehensive Income	Amounts Recognized in AOCI: Net actuarial loss $ 98,057 87,438 Total $ 98,057 87,438
Schedule of Other Information as of December 31	Other Information as of December 31: Accumulated benefit obligation $ 334,679 364,411
Schedule of Components Of Net Periodic Benefit Cost And Other Amounts Recognized In Other Comprehensive Income	Pension Plan ($ in thousands) 2018 2017 2016 Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Income: Net Periodic Benefit Cost: Service cost $ — — 1,647 Interest cost 12,428 12,490 12,336 Expected return on plan assets (22,767 ) (19,419 ) (17,309 ) Amortization of unrecognized actuarial loss 1,981 2,001 6,299 Total net periodic cost $ (8,358 ) (4,928 ) 2,973 Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Net actuarial loss (gain) $ 12,600 3,594 11,316 Reversal of amortization of net actuarial loss (1,981 ) (2,001 ) (6,299 ) Total recognized in other comprehensive income $ 10,619 1,593 5,017 Total recognized in net periodic benefit cost and other comprehensive income $ 2,261 (3,335 ) 7,990
Schedule Of Weighted- Average Expense and Liability Assumptions	Pension Plan 2018 2017 2016 Weighted-Average Expense Assumptions for the years ended December 31: Discount rate 3.78 % 4.41 4.69 Expected return on plan assets 6.36 6.24 6.37 Rate of compensation increase 1 — — — Weighted-Average Liability Assumptions as of December 31: Discount rate 4.46 % 3.78
Schedule of Allocation of Plan Assets	2018 2017 Target Percentage 2 Actual Percentage Actual Percentage Return seeking assets 1 15%-70% 43 % 58 % Liability hedging assets 35%-75% 38 % 40 % Short-term investments 3 0%-2% 19 % 2 % Total 100 % 100 % 100 %
Schedule of Quantitative Disclosures of our Financial Assets that were Measured at Fair Value	December 31, 2018 Fair Value Measurements Using ($ in thousands) Assets Measured at Fair Value Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) 1 Significant Other Observable Inputs (Level 2) 1 Significant Unobservable Inputs (Level 3) Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 121,310 78,381 42,929 — Foreign government 23,131 — 23,131 — Obligations of states and political subdivisions 1,138,469 — 1,138,469 — Corporate securities 1,617,408 — 1,617,408 — CLO and other ABS 717,362 — 709,953 7,409 CMBS 527,078 — 527,078 — RMBS 1,128,342 — 1,128,342 — Total AFS fixed income securities 5,273,100 78,381 5,187,310 7,409 Equity securities: Common stock 2 144,727 107,397 — — Preferred stock 2,912 2,912 — — Total equity securities 147,639 110,309 — — Short-term investments 323,864 321,370 2,494 — Total assets measured at fair value $ 5,744,603 510,060 5,189,804 7,409 December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets Measured at Fair Value Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) 1 Significant Other Observable Inputs (Level 2) 1 Significant Unobservable Inputs (Level 3) Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 49,740 24,652 25,088 — Foreign government 18,555 — 18,555 — Obligations of states and political subdivisions 1,582,970 — 1,582,970 — Corporate securities 1,617,468 — 1,617,468 — CLO and other ABS 795,458 — 795,458 — CMBS 383,449 — 376,895 6,554 RMBS 714,882 — 714,882 — Total AFS fixed income securities 5,162,522 24,652 5,131,316 6,554 AFS equity securities: Common stock 167,757 138,640 — 5,398 Preferred stock 14,948 14,948 — — Total AFS equity securities 182,705 153,588 — 5,398 Total AFS securities 5,345,227 178,240 5,131,316 11,952 Short-term investments 165,555 165,555 — — Total assets measured at fair value $ 5,510,782 343,795 5,131,316 11,952 1 There were no transfers of securities between Level 1 and Level 2. 2 In accordance with ASU 2015-07, investments amounting to $37.3 million and $23.7 million at December 31, 2018 and December 31, 2017, respectively, were measured at fair value using the net asset value per share (or its practical expedient) and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to total assets measured at fair value.
Schedule of Expected Benefit Payments	Payments ($ in thousands) Pension Plan Benefits Expected to be Paid in Future Fiscal Years: 2019 $ 13,920 2020 13,869 2021 15,026 2022 16,159 2023 17,134 2024-2028 99,197
Retirement Income Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Quantitative Disclosures of our Financial Assets that were Measured at Fair Value	December 31, 2018 Fair Value Measurements at 12/31/18 Using ($ in thousands) Assets Measured at Fair Value At 12/31/18 Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description Return seeking assets: Global equity $ 113,409 113,409 — — Private assets 1 : Limited partnerships (at net asset value): Real assets 16,818 — — — Private equity 878 — — — Private credit 262 — — — Hedge fund 7,889 — — — Total limited partnerships 25,847 — — — Other private assets 3,780 — — — Total private assets 29,627 — — — Total return seeking assets 143,036 113,409 — — Liability hedging assets: Fixed income 106,000 106,000 — — U.S. Treasury overlay 18,528 18,528 — — Total liability hedging assets 124,528 124,528 — — Cash and short-term investments: Short-term investments 62,788 62,788 — — Deposit administration contracts 1,482 — 1,482 — Total cash and short-term investments 64,270 62,788 1,482 — Total invested assets $ 331,834 300,725 1,482 — December 31, 2017 Fair Value Measurements at 12/31/17 Using ($ in thousands) Assets Measured at Fair Value At 12/31/17 Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Description Return seeking assets: Long-duration fixed income: Global asset allocation fund $ 41,309 41,309 — — Global equity: Non-U.S. equity 67,989 67,989 — — U.S. equity 66,353 66,353 — — Total global equity 134,342 134,342 — — Private assets (limited partnerships, at net asset value) 1 : Real assets 16,305 — — — Private equity 1,096 — — — Private credit 460 — — — Hedge fund 15,192 — — — Total limited partnerships 33,053 — — — Other private assets 980 — — 980 Total private assets 34,033 — — 980 Total return seeking assets 209,684 175,651 — 980 Liability hedging assets: Long-duration fixed income: Extended duration fixed income 146,837 146,837 — — Total liability hedging assets 146,837 146,837 — — Cash and short-term investments: Short-term investments 4,939 4,939 — — Deposit administration contracts 1,615 — 1,615 — Total cash and short-term investments 6,554 4,939 1,615 — Total invested assets $ 363,075 327,427 1,615 980 1 In accordance with ASU 2015-07, certain investments that are measured at fair value using the net asset value per share (or its practical expedient) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to total Pension Plan invested assets.

Share-Based Payments (Tables)

Share-Based Payments (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule Of Share-Based Compensation Plan Approval	Plan Approvals Stock Plan Approved effective as of May 1, 2014 by stockholders on April 23, 2014. Most recently amended and restated plan was approved effective May 2, 2018 by stockholders on May 2, 2018. Cash Plan Approved effective April 1, 2005 by stockholders on April 27, 2005. ESPP Approved by stockholders on April 29, 2009 effective July 1, 2009. Agent Plan Approved by stockholders on April 26, 2006.
Schedule of Types of Share-Based Payments Issued	Plan Types of Share-Based Payments Issued Stock Plan Qualified and nonqualified stock options, stock appreciation rights ("SARs"), restricted stock, restricted stock units ("RSUs"), stock grants, and other awards valued in whole or in part by reference to the Parent's common stock. The maximum exercise period for an option grant under this plan is 10 years from the date of the grant. Dividend equivalent units ("DEUs") are earned during the vesting period on RSU grants. The DEUs are reinvested in the Parent's common stock at fair value on each dividend payment date. The requisite service period for grants to employees under this plan is the lesser of: (i) the stated vested date, which is typically three years from issuance; or (ii) the date the employee becomes eligible to retire. Cash Plan Cash incentive units (“CIUs”). The initial dollar value of each CIU will be adjusted to reflect the percentage increase or decrease in the total shareholder return on the Parent's common stock over a specified performance period. In addition, for certain grants, the number of CIUs granted will be increased or decreased to reflect our performance on specified performance indicators as compared to targeted peer companies. The requisite service period for grants under this plan is the lesser of: (i) the stated vested date, which is typically three years from issuance; or (ii) the date the employee becomes eligible to retire. ESPP Enables employees to purchase shares of the Parent’s common stock. The purchase price is the lower of: (i) 85% of the closing market price at the time the option is granted; or (ii) 85% of the closing price at the time the option is exercised. Shares are generally issued on June 30 and December 31 of each year. Agent Plan Quarterly offerings to purchase the Parent's common stock at a 10% discount with a one year restricted period during which the shares purchased cannot be sold or transferred. Only our independent retail insurance agencies and wholesale general agencies, and certain eligible persons associated with the agencies, are eligible to participate in this plan.
Schedule of Share-Based Compensation Shares Authorized and Available for Issuance	As of December 31, 2018 Authorized Available for Issuance Awards Outstanding Stock Plan 4,750,000 3,461,192 864,478 ESPP 1,500,000 429,181 — Agent Plan 3,000,000 1,776,359 —
Schedule of Share-Based Compensation Retired Plans	December 31, 2018 Types of Share-Based Payments Issued Reserve Shares Awards Outstanding 1 Plan 2005 Omnibus Stock Plan ("2005 Stock Plan") Qualified and nonqualified stock options, SARs, restricted stock, RSUs, phantom stock, stock bonuses, and other awards in such amounts and with such terms and conditions as it determined, subject to the provisions of the 2005 Stock Plan. The maximum exercise period for an option grant under this plan is 10 years from the date of the grant. DEUs are earned during the vesting period on RSU grants. The DEUs are reinvested in the Parent's common stock at fair value on each dividend payment date. 2,099,403 174,003 Parent's Stock Compensation Plan for Non-employee Directors ("Directors Stock Compensation Plan") Directors could elect to receive a portion of their annual compensation in shares of the Parent's common stock. 65,770 65,770 1 Awards outstanding under the 2005 Stock Plan consisted of 47,268 shares deferred by our non-employee directors and 126,735 stock options.
Schedule of Summary of Restricted Stock Units Transactions under Share-Based Payment Plans	Number Weighted Unvested RSU awards at December 31, 2017 865,587 $ 33.66 Granted in 2018 303,550 55.96 Vested in 2018 (303,606 ) 26.57 Forfeited in 2018 (19,226 ) 42.62 Unvested RSU awards at December 31, 2018 846,305 $ 44.00
Schedule of Summary of Stock Option Transactions under Share Based Payment Plans	Number Weighted Weighted Aggregate Outstanding at December 31, 2017 229,864 $ 15.38 Granted in 2018 — — Exercised in 2018 (103,129 ) 16.62 Forfeited or expired in 2018 — — Outstanding at December 31, 2018 126,735 $ 14.37 0.80 $ 5,903 Exercisable at December 31, 2018 126,735 $ 14.37 0.80 $ 5,903
Schedule of Share-Based Compensation ESPP and ASPP Shares Granted	2018 2017 2016 ESPP Issuances 70,448 75,093 88,432 Agent Plan Issuances 41,134 49,794 69,867
Schedule of Weighted Average Assumptions for Employee Stock Purchase Plan	ESPP 2018 2017 2016 Risk-free interest rate 1.88 % 1.07 0.47 Expected term 6 months 6 months 6 months Dividend yield 1.3 % 1.3 1.7 Expected volatility 18 % 24 31
Schedule of Weighted-Average Fair Value of Options and Stock Per Share	2018 2017 2016 RSUs $ 55.96 42.66 32.53 ESPP: Six month option 2.67 2.73 2.63 Discount of grant date market value 8.50 7.06 5.23 Total ESPP 11.17 9.79 7.86 Agent Plan: Discount of grant date market value 5.99 5.04 3.79
Schedule of Compensation Cost for Share-based Payment Arrangements	($ in millions) 2018 2017 2016 Share-based compensation expense, pre-tax $ 19.3 31.2 30.3 Income tax benefit, including the benefit related to stock grants that have vested during the year (7.0 ) (15.0 ) (10.3 ) Share-based compensation expense, after-tax $ 12.3 16.2 20.0

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Commitments For Non-Cancelable Leases	($ in millions) Capital Leases Operating Leases Total 2019 $ 0.7 7.8 8.5 2020 0.1 7.4 7.5 2021 — 5.1 5.1 2022 — 3.6 3.6 2023 — 2.9 2.9 After 2023 — 9.7 9.7 Total minimum payment required $ 0.8 36.5 37.3

Statutory Financial Informati_2

Statutory Financial Information, Capital Requirements, and Restrictions on Dividends and Transfers of Funds (Tables)	12 Months Ended
	Dec. 31, 2018
Insurance [Abstract]
Schedule of Insurance Subsidiaries Statutory Surplus Data	State of Domicile Unassigned Surplus Statutory Surplus Statutory Net Income ($ in millions) 2018 2017 2018 2017 2018 2017 2016 SICA New Jersey $ 478.6 455.5 632.8 609.7 78.0 84.6 72.2 Selective Way Insurance Company ("SWIC") New Jersey 300.2 276.1 349.3 325.1 47.5 43.6 41.2 SICSC Indiana 119.4 112.9 150.7 144.1 16.5 17.9 17.4 SICSE Indiana 92.2 86.2 117.7 111.8 12.9 14.7 13.4 SICNY New York 86.5 78.8 114.2 106.5 12.0 13.4 12.9 Selective Insurance Company of New England ("SICNE") New Jersey 19.9 16.1 50.0 46.3 5.6 6.3 5.9 Selective Auto Insurance Company of New Jersey ("SAICNJ") New Jersey 50.3 42.1 93.2 84.9 9.9 11.4 11.5 MUSIC New Jersey 23.0 21.4 91.5 89.9 9.4 10.3 9.7 Selective Casualty Insurance Company ("SCIC") New Jersey 44.9 34.5 119.3 109.0 13.3 13.4 12.6 Selective Fire and Casualty Insurance Company ("SFCIC") New Jersey 17.8 13.7 49.7 45.6 5.5 5.6 5.5 Total $ 1,232.8 1,137.3 1,768.4 1,672.9 210.6 221.2 202.3
Schedule of Insurance Subsidiaries Dividend Paid To Parent	Dividends Twelve Months ended December 31, 2018 2019 ($ in millions) State of Domicile Ordinary Dividends Paid Maximum Ordinary Dividends SICA New Jersey $ 43.0 $ 78.0 SWIC New Jersey 19.0 47.5 SICSC Indiana 10.0 16.5 SICSE Indiana 7.5 12.9 SICNY New York 4.5 11.4 SICNE New Jersey 2.0 5.6 SAICNJ New Jersey 2.5 9.9 MUSIC New Jersey 7.1 9.4 SCIC New Jersey 3.0 13.3 SFCIC New Jersey 1.5 5.5 Total $ 100.1 $ 210.0

Quarterly Financial Informati_2

Quarterly Financial Information (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	First Quarter Second Quarter Third Quarter Fourth Quarter 1 (unaudited, $ in thousands, except per share data) 2018 2017 2018 2017 2018 2017 2018 2017 Net premiums earned $ 591,828 560,854 604,836 568,030 614,277 572,055 625,288 590,088 Net investment income earned 43,231 37,419 45,553 41,430 52,443 40,446 54,109 42,587 Net realized and unrealized (losses) gains 2 (10,549 ) (1,045 ) (1,652 ) 1,734 (4,787 ) 6,798 (37,935 ) (1,128 ) Other income 2,179 3,241 3,179 3,291 2,538 1,994 1,542 2,190 Total revenues 626,689 600,469 651,916 614,485 664,471 621,293 643,004 633,737 Income before federal income taxes 19,931 67,574 72,525 58,929 67,130 67,315 52,135 68,150 Net income 18,925 50,440 58,819 41,426 55,435 46,718 45,760 30,242 Net income per share: Basic 0.32 0.87 1.00 0.71 0.94 0.80 0.77 0.52 Diluted 0.32 0.85 0.99 0.70 0.93 0.79 0.76 0.51 1 Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information. 2 Effective January 1, 2018, changes in unrealized gains and losses on our equity portfolio are recognized in income through "Net unrealized losses on equity securities" on our Consolidated Statements of Income, as a result of our adoption of ASU 2016-01 . See Note 3. "Adoption of Accounting Pronouncements" above. The addition of all quarters may not agree to annual amounts on the Financial Statements due to rounding.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended			12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Percent of Portfolio Level 3 Securities				1.00%
Percent of Investment Portfolio Comprised of Fixed Income Securities				89.00%
Percent of Fixed Income Securities Comprised of AFS				99.00%
Percent of Fixed Income Securities Comprised of HTM				1.00%
Percent of Loan Principal				102.00%
Depreciation expense				$ 19.5	$ 17.8	$ 17.4
Investment yields before tax assumed in premium deficiency assessment	3.30%	2.90%	2.40%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Property and Equipment) (Details)	12 Months Ended
	Dec. 31, 2018
Computer hardware [Member]
Property, Plant and Equipment, Estimated Useful Lives	3
Furniture and fixtures [Member]
Property, Plant and Equipment, Estimated Useful Lives	10
Maximum [Member] | Computer software [Member]
Property, Plant and Equipment, Estimated Useful Lives	5
Maximum [Member] | Software licenses [Member]
Property, Plant and Equipment, Estimated Useful Lives	5
Maximum [Member] | Internally developed software [Member]
Property, Plant and Equipment, Estimated Useful Lives	10
Maximum [Member] | Building and improvements [Member]
Property, Plant and Equipment, Estimated Useful Lives	40
Minimum [Member] | Computer software [Member]
Property, Plant and Equipment, Estimated Useful Lives	3
Minimum [Member] | Software licenses [Member]
Property, Plant and Equipment, Estimated Useful Lives	3
Minimum [Member] | Internally developed software [Member]
Property, Plant and Equipment, Estimated Useful Lives	5
Minimum [Member] | Building and improvements [Member]
Property, Plant and Equipment, Estimated Useful Lives	5

Adoption of Accounting Pronou_3

Adoption of Accounting Pronouncements Adoption of Accounting Pronouncements (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Undistributed (gains) losses of equity method investments		$ (8,341)	$ (5,362)	$ 318
Distributions in excess of current year income of equity method investments		2,924	552	0
Increase in other assets		(372)	(2,643)	(4,979)
Net cash provided by operating activities		454,944	379,545	329,509
Distributions from other investments		28,379	21,843	24,202
Net cash used in investing activities		(435,688)	(332,658)	(320,736)
Operating Lease, Right-of-Use Asset		20,800
Operating Lease, Liability		20,400
Finance Lease, Right-of-Use Asset		900
Finance Lease, Liability		900
Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Undistributed (gains) losses of equity method investments			(6,393)	(2,316)
Distributions in excess of current year income of equity method investments			0	0
Increase in other assets			(9,872)	(30,071)
Net cash provided by operating activities			370,733	301,783
Distributions from other investments			23,426	26,837
Net cash used in investing activities			(331,075)	(318,101)
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment		30,726	0	0
Accumulated other comprehensive (loss) income [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	[1]		25,019
Accumulated other comprehensive (loss) income [Member] | Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment		30,726	0	0
Accumulated other comprehensive (loss) income [Member] | Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment		(5,707)	0	0
Retained Earnings [Member] | Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment		(30,726)	0	0
Retained Earnings [Member] | Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment		5,707	$ 0	$ 0
Retained Earnings [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment		$ (1,000)
[1]	Upon adoption of ASU 2016-01 and ASU 2018-02 in the first quarter of 2018, we recognized a $25.0 million cumulative-effect adjustment to the opening balance of AOCI, which represents the after-tax net unrealized gain on our equity portfolio as of December 31, 2017 and the one-time reclassification from AOCI to retained earnings for the stranded tax assets that were created in AOCI from the enactment of Tax Reform. See Note 3. "Adoption of Accounting Pronouncements" above for additional information.

Statements of Cash Flow (Cash F

Statements of Cash Flow (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest	$ 23,992	$ 23,905	$ 22,098
Federal income tax	29,193	62,000	46,405
Corporate actions related to equity securities	944	4,725	3,263
Assets acquired under capital lease arrangements	4,119	278	3,151
Non-cash purchase of property and equipment	291	0	78
AFS Fixed Income Securities [Member]
Corporate actions related to fixed income securities, AFS	$ 52,277	$ 22,511	$ 23,579

Statements of Cash Flow Stateme

Statements of Cash Flow Statements of Cash Flow (Cash and Restricted Cash) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Cash	$ 505	$ 534
Restricted cash	16,414	44,176
Total cash and restricted cash shown in the Statements of Cash Flows	$ 16,919	$ 44,710	$ 37,405	$ 12,754

Investments (Unrealized Gains o

Investments (Unrealized Gains on Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net unrealized gains	$ 2,391	$ 124,679	$ 64,804
Deferred income tax expense	(502)	(44,103)	(22,681)
Net unrealized gains, net of deferred income tax	1,889	80,576	42,123
Increase (decrease) in net unrealized gains in OCI, net of deferred income tax	(65,881)	38,453	(2,873)
AFS Fixed Income Securities [Member]
Net unrealized gains	2,302	85,806	38,781
Equity Securities [Member]
Net unrealized gains	0	38,894	25,864
Available-for-sale Securities [Member]
Net unrealized gains	2,302	124,700	64,645
Total HTM Securities [Member]
Net unrealized gains	89	(21)	159
Accounting Standards Update 2018-02 [Member] | Investments [Member]
Cumulative effect adjustment	(17,920)	0	0
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member]
Cumulative effect adjustment	5,707	0	0
Accounting Standards Update 2016-01 [Member]
Cumulative effect adjustment	30,726	0	0
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Cumulative effect adjustment	$ (30,726)	$ 0	$ 0

Investments (Held-To-Maturity S

Investments (Held-To-Maturity Securities Disclosure) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost	$ 37,021	$ 42,150
Net Unrealized Gains (Losses)	89	(21)
Total HTM fixed income securities carrying value	37,110	42,129
Unrecognized Holding Gains	1,359	2,026
Unrecognized Holding Losses	(152)	(55)
Total HTM fixed income securities fair value	38,317	44,100
Obligations of States and Political Subdivisions [Member]
Amortized Cost	17,431	25,154
Net Unrealized Gains (Losses)	39	84
Total HTM fixed income securities carrying value	17,470	25,238
Unrecognized Holding Gains	504	1,023
Unrecognized Holding Losses	(5)	0
Total HTM fixed income securities fair value	17,969	26,261
Corporate Securities [Member]
Amortized Cost	19,590	16,996
Net Unrealized Gains (Losses)	50	(105)
Total HTM fixed income securities carrying value	19,640	16,891
Unrecognized Holding Gains	855	1,003
Unrecognized Holding Losses	(147)	(55)
Total HTM fixed income securities fair value	$ 20,348	$ 17,839

Investments (Available-For-Sale

Investments (Available-For-Sale Securities Disclosure) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost		$ 5,220,527
Unrealized Gains		130,058
Unrealized Losses		(5,358)
Total AFS securities		5,345,227
AFS Fixed Income Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	$ 5,270,798	5,076,716
Unrealized Gains	47,369	90,867
Unrealized Losses	(45,067)	(5,061)
Total AFS securities	5,273,100	5,162,522
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	120,092	49,326
Unrealized Gains	1,810	647
Unrealized Losses	(592)	(233)
Total AFS securities	121,310	49,740
AFS Fixed Income Securities [Member] | Foreign Government [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	23,202	18,040
Unrealized Gains	36	526
Unrealized Losses	(107)	(11)
Total AFS securities	23,131	18,555
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	1,121,615	1,539,307
Unrealized Gains	19,485	44,245
Unrealized Losses	(2,631)	(582)
Total AFS securities	1,138,469	1,582,970
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	1,639,852	1,588,339
Unrealized Gains	5,521	30,891
Unrealized Losses	(27,965)	(1,762)
Total AFS securities	1,617,408	1,617,468
AFS Fixed Income Securities [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	720,193	789,152
Unrealized Gains	4,112	6,508
Unrealized Losses	(6,943)	(202)
Total AFS securities	717,362	795,458
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	527,409	382,727
Unrealized Gains	3,417	1,563
Unrealized Losses	(3,748)	(841)
Total AFS securities	527,078	383,449
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	1,118,435	709,825
Unrealized Gains	12,988	6,487
Unrealized Losses	(3,081)	(1,430)
Total AFS securities	$ 1,128,342	714,882
Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost		143,811
Unrealized Gains		39,191
Unrealized Losses		(297)
Total AFS securities		182,705
Equity Securities [Member] | Common Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost		129,696
Unrealized Gains		38,287
Unrealized Losses		(226)
Total AFS securities		167,757
Equity Securities [Member] | Nonredeemable Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost		14,115
Unrealized Gains		904
Unrealized Losses		(71)
Total AFS securities		$ 14,948

Investments (Number of Securiti

Investments (Number of Securities in an Unrealized Unrecognized Loss Position) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Percentage Decline in Fair Value Percentage of Amortized Cost	2.00%	1.00%
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	$ 200	$ 100
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		878,126
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(4,961)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		35,686
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		(397)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value		913,812
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		(5,358)
AFS Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	2,142,433	869,566
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(36,948)	(4,664)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	275,174	35,686
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(8,119)	(397)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	2,417,607	905,252
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(45,067)	(5,061)
Equity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		8,560
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(297)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value		8,560
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		(297)
U.S. Government and Government Agencies [Member] | AFS Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	6,693	23,516
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(174)	(233)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	23,163	250
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(418)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	29,856	23,766
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(592)	(233)
Foreign Government [Member] | AFS Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	12,208	1,481
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(93)	(11)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,482	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(14)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	13,690	1,481
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(107)	(11)
Obligations of States and Political Subdivisions [Member] | AFS Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	196,798	107,514
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(2,074)	(422)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	42,821	14,139
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(557)	(160)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	239,619	121,653
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(2,631)	(582)
Corporate Securities [Member] | AFS Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,041,952	238,326
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(23,649)	(1,744)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	78,953	3,228
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(4,316)	(18)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	1,120,905	241,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(27,965)	(1,762)
Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | AFS Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	516,106	74,977
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(6,750)	(196)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	16,800	1,655
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(193)	(6)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	532,906	76,632
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(6,943)	(202)
Commercial Mortgage Backed Securities [Member] | AFS Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	229,338	154,267
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(2,548)	(773)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	66,294	5,214
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,200)	(68)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	295,632	159,481
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(3,748)	(841)
Residential Mortgage Backed Securities [Member] | AFS Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	139,338	269,485
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,660)	(1,285)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	45,661	11,200
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,421)	(145)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	184,999	280,685
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (3,081)	(1,430)
Common Stock [Member] | Equity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		4,727
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(226)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value		4,727
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		(226)
Nonredeemable Preferred Stock [Member] | Equity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		3,833
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(71)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value		3,833
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (71)

Investments (Fixed Maturity Sec

Investments (Fixed Maturity Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
AFS due in one year or less fair value	$ 188,309
AFS due after one year through five years fair value	2,040,395
AFS due after five years through 10 years fair value	2,863,528
AFS due after 10 years fair value	180,868
Fixed income securities, available-for-sale securities	5,273,100	$ 5,162,522
HTM due in one year or less carrying value	13,502
HTM due after one year through five years carrying value	17,308
HTM due after five years through 10 years carrying value	6,300
HTM due after 10 years carrying value	0
Total HTM fixed income securities carrying value	37,110	42,129
HTM due in one year or less fair value	13,693
HTM due after one year through five years fair value	18,260
HTM due after five years through 10 years fair value	6,364
HTM due after 10 years fair value	0
Total HTM fixed income securities fair value	$ 38,317	$ 44,100

Investments (Other Investment P

Investments (Other Investment Portfolio by Strategy and the Remaining Commitment Amount Associated With Each Strategy) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Carrying Value	$ 178,938	$ 132,268
Other Investment Portfolio [Member]
Carrying Value	178,938	132,268
Remaining Commitment	202,270	220,999
Maximum Exposure to Loss	381,208	353,267
Alternative Investments [Member]
Carrying Value	153,896	115,373
Remaining Commitment	202,270	220,999
Maximum Exposure to Loss	356,166	336,372
Private Equity [Member] | Alternative Investments [Member]
Carrying Value	84,352	52,251
Remaining Commitment	93,688	99,026
Maximum Exposure to Loss	178,040	151,277
Private Credit Funds [Member] | Alternative Investments [Member]
Carrying Value	41,682	37,743
Remaining Commitment	81,453	94,959
Maximum Exposure to Loss	123,135	132,702
Real Assets [Member] | Alternative Investments [Member]
Carrying Value	27,862	25,379
Remaining Commitment	27,129	27,014
Maximum Exposure to Loss	54,991	52,393
Other Securities [Member]
Carrying Value	25,042	16,895
Remaining Commitment	0	0
Maximum Exposure to Loss	$ 25,042	$ 16,895

Investments (Aggregated Balance

Investments (Aggregated Balance Sheet Summarized Financial Information for Partnerships in our Alternative Investment Portfolio) (Details) - Investments Accounted For Under The Equity Method [Member] - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Investments	$ 28,292	$ 21,046
Total assets	30,377	22,357
Total liabilities	4,532	4,767
Partners' capital	$ 25,845	$ 17,590

Investments (Aggregated Income

Investments (Aggregated Income Statement Summarized Financial Information for Partnerships in our Alternative Investment Portfolio) (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2015
Schedule of Equity Method Investments [Line Items]
Net investment income earned	$ 54,109		$ 52,443	$ 45,553	$ 43,231	$ 42,587		$ 40,446	$ 41,430	$ 37,419	$ 195,336	$ 161,882		$ 130,754
Investments Accounted For Under The Equity Method [Member]
Schedule of Equity Method Investments [Line Items]
Net investment income (loss)													$ 134,000		$ (143,000)	$ (44,000)
Realized gains													1,981,000		325,000	1,374,000
Net change in unrealized appreciation (depreciation)													1,303,000		2,894,000	(719,000)
Net Income													$ 3,418,000		$ 3,076,000	$ 611,000
Alternative Investments [Member]
Schedule of Equity Method Investments [Line Items]
Net investment income earned											$ 17,600	$ 12,700		$ 3,100
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Investments (Credit Concentrati

Investments (Credit Concentration Risk) (Details)	Dec. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Maximum exposure to credit concentration risk of the Company's stockholder's equity other than certain U.S. government agencies	10.00%	10.00%

Investments (Investments Pledge

Investments (Investments Pledged as Collateral) (Details) $ in Millions	Dec. 31, 2018USD ($)
Debt Securities, Available-for-sale [Line Items]
Assets Held by Insurance Regulators	$ 26.7
Securities pledged as collateral for reinsurance obligations	155.5
U.S. Government and Government Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held by Insurance Regulators	22.5
Securities pledged as collateral for reinsurance obligations	22.5
Obligations of States and Political Subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	0
Assets Held by Insurance Regulators	3.9
Securities pledged as collateral for reinsurance obligations	3.9
Corporate Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held by Insurance Regulators	0.3
Securities pledged as collateral for reinsurance obligations	0.3
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held by Insurance Regulators	0
Securities pledged as collateral for reinsurance obligations	25.3
Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held by Insurance Regulators	0
Securities pledged as collateral for reinsurance obligations	103.5
Federal Home Loan Bank of New York [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	63.6
Federal Home Loan Bank of New York [Member] | U.S. Government and Government Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	0
Federal Home Loan Bank of New York [Member] | Corporate Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	0
Federal Home Loan Bank of New York [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	18.1
Federal Home Loan Bank of New York [Member] | Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	45.5
Federal Home Loan Bank of Indianapolis [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	65.2
Federal Home Loan Bank of Indianapolis [Member] | U.S. Government and Government Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	0
Federal Home Loan Bank of Indianapolis [Member] | Obligations of States and Political Subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	0
Federal Home Loan Bank of Indianapolis [Member] | Corporate Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	0
Federal Home Loan Bank of Indianapolis [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	7.2
Federal Home Loan Bank of Indianapolis [Member] | Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	$ 58

Investments (Net Investment Inc

Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement [Line Items]
Net investment income earned	$ 54,109		$ 52,443	$ 45,553	$ 43,231	$ 42,587		$ 40,446	$ 41,430	$ 37,419	$ 195,336	$ 161,882	$ 130,754
Fixed Income Securities [Member]
Statement [Line Items]
Net investment income earned											178,104	153,230	129,306
Equity Securities [Member]
Statement [Line Items]
Net investment income earned											7,764	6,442	7,368
Short-term Investments [Member]
Statement [Line Items]
Net investment income earned											3,472	1,526	686
Other Investment Portfolio [Member]
Statement [Line Items]
Net investment income earned											17,799	12,871	2,940
Investment Expenses [Member]
Statement [Line Items]
Net investment income earned											$ (11,803)	$ (12,187)	$ (9,546)
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Investments (OTTI by Asset Type

Investments (OTTI by Asset Type) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OTTI Losses Gross	$ 6,579	$ 4,809	$ 8,509
OTTI included in OCI	0	(36)	10
Total OTTI charges recognized in earnings	6,579	4,845	8,499
Other Investments [Member]
OTTI Losses Gross	1,893	190
OTTI included in OCI	0	0
Total OTTI charges recognized in earnings	1,893	190
AFS Fixed Income Securities [Member]
OTTI Losses Gross	4,686	3,184	5,191
OTTI included in OCI	0	(36)	10
Total OTTI charges recognized in earnings	4,686	3,220	5,181
AFS Fixed Income Securities [Member] | US Government Agencies Debt Securities [Member]
OTTI Losses Gross		36
OTTI included in OCI		0
Total OTTI charges recognized in earnings		36
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
OTTI Losses Gross		612	2,797
OTTI included in OCI		0	0
Total OTTI charges recognized in earnings		612	2,797
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
OTTI Losses Gross	1,783	587	1,880
OTTI included in OCI	0	0	0
Total OTTI charges recognized in earnings	1,783	587	1,880
AFS Fixed Income Securities [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member]
OTTI Losses Gross		96	19
OTTI included in OCI		0	0
Total OTTI charges recognized in earnings		96	19
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
OTTI Losses Gross		670	220
OTTI included in OCI		0	0
Total OTTI charges recognized in earnings		670	220
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
OTTI Losses Gross	2,903	1,183	275
OTTI included in OCI	0	(36)	10
Total OTTI charges recognized in earnings	$ 2,903	1,219	265
Available-for-sale Securities [Member] | Equity Securities [Member]
OTTI Losses Gross		1,435	3,318
OTTI included in OCI		0	0
Total OTTI charges recognized in earnings		1,435	3,318
Common Stock [Member] | Available-for-sale Securities [Member] | Equity Securities [Member]
OTTI Losses Gross		1,435	3,316
OTTI included in OCI		0	0
Total OTTI charges recognized in earnings		$ 1,435	3,316
Nonredeemable Preferred Stock [Member] | Available-for-sale Securities [Member] | Equity Securities [Member]
OTTI Losses Gross			2
OTTI included in OCI			0
Total OTTI charges recognized in earnings			$ 2

Investments (Components of Net

Investments (Components of Net Realized and Unrealized Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1],[2]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	[1],[2]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gain (Loss) on Securities [Line Items]
Unrealized Gain (Loss) on Investments																	$ (3,100)
Unrealized Gain Loss on Equity Securities Sold																	(26,300)
Net realized investment (losses) gains on disposals																	(18,975)	$ 11,204	$ 3,562
OTTI charges																	(6,579)	(4,845)	(8,499)
Net realized (losses) gains																	(25,554)	6,359	(4,937)
Unrealized losses recognized in income on equity securities																	(29,369)	0	0
Total net realized and unrealized (losses) gains	$ (37,935)		$ (4,787)		$ (1,652)		$ (10,549)		$ (1,128)		$ 6,798		$ 1,734		$ (1,045)		(54,923)	6,359	(4,937)
Fixed Income Securities [Member]
Gain (Loss) on Securities [Line Items]
Net realized investment (losses) gains on disposals																	(34,953)	6,944	(3,668)
Equity Securities [Member]
Gain (Loss) on Securities [Line Items]
Net realized investment (losses) gains on disposals																	18,695	4,629	7,244
Short-term Investments [Member]
Gain (Loss) on Securities [Line Items]
Net realized investment (losses) gains on disposals																	(3)	(4)	(13)
Other Investments [Member]
Gain (Loss) on Securities [Line Items]
Net realized investment (losses) gains on disposals																	$ (2,714)	$ (365)	$ (1)
[1]	Effective January 1, 2018, changes in unrealized gains and losses on our equity portfolio are recognized in income through "Net unrealized losses on equity securities" on our Consolidated Statements of Income, as a result of our adoption of ASU 2016-01. See Note 3. "Adoption of Accounting Pronouncements" above.
[2]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Investments (Net Realized Gains

Investments (Net Realized Gains Losses on Disposal) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items]
HTM fixed income securities gains	$ 2	$ 44	$ 3
HTM fixed income securities losses	0	(1)	(1)
Equity securities gains	23,203
Equity securities losses	(4,508)
Short term investments gains	(7)	(2)	0
Short term investments losses	10	6	(13)
Other investment securities gains	0	494	3
Other investment securities losses	(2,714)	(859)	(4)
Net realized investment (losses) gains on disposals	(18,975)	11,204	3,562
Sale of fixed income securities, available-for-sale	2,030,664	1,197,920	926,470
Sale of equity securities	113,339
Sale of equity securities, available-for-sale		37,960	119,617
Fixed Income Securities [Member]
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items]
AFS securities gains	5,460	10,193	7,741
AFS securities losses	(40,415)	(3,292)	(11,411)
Equity Securities [Member]
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items]
AFS securities gains		5,829	8,108
AFS securities losses		(1,200)	(864)
Net realized investment (losses) gains on disposals	$ 18,695	$ 4,629	$ 7,244

Comprehensive Income (Component

Comprehensive Income (Components of Comprehensive Income-Gross and Net of Tax) (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income before federal income tax	$ 52,135		$ 67,130	$ 72,525	$ 19,931	$ 68,150		$ 67,315	$ 58,929	$ 67,574	$ 211,721	$ 261,968	$ 219,955
Income Tax Expense (Benefit)											32,782	93,142	61,460
Net income	$ 45,760	[1]	$ 55,435	$ 58,819	$ 18,925	$ 30,242	[1]	$ 46,718	$ 41,426	$ 50,440	178,939	168,826	158,495
Unrealized holding gains (losses) during the period, Gross											(123,145)	66,894	(9,195)
Unrealized holding gains (losses) during the period, Tax											(25,861)	23,879	(3,218)
Unrealized holding gains (losses) arising during period, Net											(97,284)	43,015	(5,977)
Non-credit portion of other-than-temporary impairment losses recognized in other comprehensive income, Gross												36	(10)
Non-Credit Portion of Other-Than-Temporary Impairment Losses Recognized In Other Comprehensive Income, Tax												13	(4)
Non-credit portion of other-than-temporary impairments recognized in other comprehensive income, Net												23	(6)
Amount reclassified into net income: HTM securities, Gross											110	(179)	(141)
Amounts reclassified into net income: HTM securities, Tax											23	(63)	(49)
Amount reclassified into net income: HTM securities, Net											87	(116)	(92)
Non-credit OTTI, Gross												104	213
Non-credit OTTI, Tax												36	75
Amounts reclassified into net income: Non-credit other-than-temporary impairment											0	68	138
Realized (gains) losses on AFS securities, Gross											39,641	(6,979)	4,713
Realized (gains) losses on AFS securities, Tax											8,325	(2,442)	1,649
Realized (gains) losses on available for sale securities											31,316	(4,537)	3,064
Net unrealized gains (losses), Gross											(83,394)	59,876	(4,420)
Net unrealized gains (losses), Tax											(17,513)	21,423	(1,547)
Total unrealized (losses) gains on investment securities											(65,881)	38,453	(2,873)
Net actuarial (loss) gain, Gross											(11,273)	(4,684)	(12,079)
Net actuarial (loss) gain, Tax											(2,367)	(984)	(4,227)
Net actuarial (loss) gain, Net											(8,906)	(3,700)	(7,852)
Amount reclassified into net i ncome: Net actuarial loss, Gross											2,127	2,102	6,462
Amount reclassified into Net Income: Net actuarial loss, Tax											447	735	2,262
Amount reclassified into net income: Net actuarial loss, Net											1,680	1,367	4,200
Defined pension and other post-retirement benefit plans, Gross											(9,146)	(2,582)	(5,617)
Defined pension and other post-retirement benefit plans, Tax											(1,920)	(249)	(1,965)
Total defined benefit pension and post-retirement plans											(7,226)	(2,333)	(3,652)
Other Comprehensive Income (Loss), Gross											(92,540)	57,294	(10,037)
Other Comprehensive Income (Loss), Tax											(19,433)	21,174	(3,512)
Other comprehensive (loss) income											(73,107)	36,120	(6,525)
Comprehensive Income, Before Tax											119,181	319,262	209,918
Comprehensive Income, Tax											13,349	114,316	57,948
Comprehensive income											$ 105,832	$ 204,946	$ 151,970
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Comprehensive Income (Compone_2

Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		$ 20,170
Amounts reclassified into net income: Non-credit other-than-temporary impairment		0	$ 68	$ 138
Amount reclassified from AOCI, HTM		87	(116)	(92)
OCI before reclassifications, Defined Benefit Pension and Post Retirement Plans		(8,906)	(3,700)	(7,852)
Amounts reclassified from AOCI,All other		31,316	(4,537)	3,064
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax		(7,226)	(2,333)	(3,652)
Other comprehensive (loss) income		(73,107)	36,120	(6,525)
Balance December,		(77,956)	20,170
Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		(59)	(150)
Cumulative effect adjustment	[1]		(12)
OCI before reclassifications		0	23
Other comprehensive (loss) income		0	91
Balance December,		(71)	(59)	(150)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		(60,405)	(58,072)
Cumulative effect adjustment	[1]		(12,213)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax		1,680	1,367
Balance December,		(79,844)	(60,405)	(58,072)
Accumulated other comprehensive (loss) income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		20,170	(15,950)
Cumulative effect adjustment	[1]		(25,019)
OCI before reclassifications		(106,190)	39,338
Amount reclassified from AOCI		33,083	(3,218)
Other comprehensive (loss) income		(73,107)	36,120	(6,525)
Balance December,		(77,956)	20,170	(15,950)
Held-to-maturity Securities [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		(14)	102
Cumulative effect adjustment	[1]		(2)
OCI before reclassifications		0	0
Other comprehensive (loss) income		87	(116)
Balance December,		71	(14)	102
Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		80,648	42,170
Cumulative effect adjustment	[1]		(12,792)
OCI before reclassifications		(97,284)	43,015
Other comprehensive (loss) income		(65,968)	38,478
Balance December,		1,888	80,648	42,170
Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		80,575	42,122
Cumulative effect adjustment	[1]		(12,806)
OCI before reclassifications		(97,284)	43,038
Amount reclassified from AOCI		31,403	(4,585)
Other comprehensive (loss) income		(65,881)	38,453
Balance December,		1,888	80,575	$ 42,122
Adjustments for New Accounting Pronouncement [Member] | Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		(71)
Balance December,			(71)
Adjustments for New Accounting Pronouncement [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		(72,618)
Balance December,			(72,618)
Adjustments for New Accounting Pronouncement [Member] | Accumulated other comprehensive (loss) income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		(4,849)
Balance December,			(4,849)
Adjustments for New Accounting Pronouncement [Member] | Held-to-maturity Securities [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		(16)
Balance December,			(16)
Adjustments for New Accounting Pronouncement [Member] | Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		67,856
Balance December,			67,856
Adjustments for New Accounting Pronouncement [Member] | Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,		$ 67,769
Balance December,			$ 67,769
[1]	Upon adoption of ASU 2016-01 and ASU 2018-02 in the first quarter of 2018, we recognized a $25.0 million cumulative-effect adjustment to the opening balance of AOCI, which represents the after-tax net unrealized gain on our equity portfolio as of December 31, 2017 and the one-time reclassification from AOCI to retained earnings for the stranded tax assets that were created in AOCI from the enactment of Tax Reform. See Note 3. "Adoption of Accounting Pronouncements" above for additional information.

Comprehensive Income (Reclassif

Comprehensive Income (Reclassification out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net realized (losses) gains											$ (25,554)	$ 6,359	$ (4,937)
Net investment income	$ 54,109	[1]	$ 52,443	$ 45,553	$ 43,231	$ 42,587	[1]	$ 40,446	$ 41,430	$ 37,419	195,336	161,882	130,754
Income before federal income tax	52,135		67,130	72,525	19,931	68,150		67,315	58,929	67,574	211,721	261,968	219,955
Income Tax Expense (Benefit)											(32,782)	(93,142)	(61,460)
Net income	$ 45,760	[1]	$ 55,435	$ 58,819	$ 18,925	$ 30,242	[1]	$ 46,718	$ 41,426	$ 50,440	178,939	168,826	158,495
Loss and loss expense incurred											1,498,134	1,345,074	1,234,797
Policy acquisition costs											331,318	333,097	321,395
Total defined benefit pension and post-retirement plans											(7,226)	(2,333)	$ (3,652)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Net income											33,083	(3,218)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Retirement Income Plan [Member]
Income before federal income tax											2,127	2,102
Income Tax Expense (Benefit)											(447)	(735)
Net income											1,680	1,367
Loss and loss expense incurred											450	450
Policy acquisition costs											1,677	1,652
Accumulated other-than-temporary impairments including portion attributable to noncontrolling interest [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Net realized (losses) gains											0	104
Income before federal income tax											0	104
Income Tax Expense (Benefit)											0	(36)
Net income											0	68
Held-to-maturity Securities [Member] | Accumulated net investment gain (loss) including portion attributable to noncontrolling interest [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Net realized (losses) gains											137	32
Net investment income											(27)	(211)
Income before federal income tax											110	(179)
Income Tax Expense (Benefit)											(23)	63
Net income											87	(116)
Available-for-sale Securities [Member] | Accumulated net investment gain (loss) including portion attributable to noncontrolling interest [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Net realized (losses) gains											39,641	(6,979)
Income before federal income tax											39,641	(6,979)
Income Tax Expense (Benefit)											(8,325)	2,442
Net income											$ 31,316	$ (4,537)
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Value and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fixed income securities, held-to-maturity	$ 37,110	$ 42,129
Debt Securities, Available-for-sale	5,273,100	5,162,522
Equity securities	147,639
Equity securities, AFS		182,705
Short-term investments	323,864	165,555
Long-term debt	439,540	439,116
Seven Point Twenty Five Percent Senior Notes [Member]
Long-term Debt, Fair Value	57,032	61,391
Six Point Seventy Percent Senior Notes [Member]
Long-term Debt, Fair Value	107,075	116,597
Five Point Eight Hundred Seventy Five Percent Senior Notes [Member]
Long-term Debt, Fair Value	177,230	186,332
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term Debt, Fair Value	24,218	24,270
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term Debt, Fair Value	24,162	24,210
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Long-term Debt, Fair Value	58,905	60,334
Carrying Amount [Member]
Fixed income securities, held-to-maturity	37,110	42,129
Debt Securities, Available-for-sale	5,273,100	5,162,522
Equity securities	147,639
Equity securities, AFS		182,705
Short-term investments	323,864	165,555
Long-term debt	439,540	439,116
Carrying Amount [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Long-term debt	49,907	49,904
Carrying Amount [Member] | Six Point Seventy Percent Senior Notes [Member]
Long-term debt	99,462	99,446
Carrying Amount [Member] | Five Point Eight Hundred Seventy Five Percent Senior Notes [Member]
Long-term debt	185,000	185,000
Carrying Amount [Member] | One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term debt	25,000	25,000
Carrying Amount [Member] | One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term debt	25,000	25,000
Carrying Amount [Member] | Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Long-term debt	60,000	60,000
Carrying Amount [Member] | Long Term Debt Excluding Issuance Costs [Member]
Long-term debt	444,369	444,350
Carrying Amount [Member] | Unamortized Debt Issuance Costs [Member]
Unamortized debt issuance costs	(4,829)	(5,234)
Fair Value [Member]
Fixed income securities, held-to-maturity	38,317	44,100
Debt Securities, Available-for-sale	5,273,100	5,162,522
Equity securities	147,639
Equity securities, AFS		182,705
Short-term investments	323,864	165,555
Long-term Debt, Fair Value	448,622	473,134
Fair Value [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Long-term Debt, Fair Value	57,032	61,391
Fair Value [Member] | Six Point Seventy Percent Senior Notes [Member]
Long-term Debt, Fair Value	107,075	116,597
Fair Value [Member] | Five Point Eight Hundred Seventy Five Percent Senior Notes [Member]
Long-term Debt, Fair Value	177,230	186,332
Fair Value [Member] | One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term Debt, Fair Value	24,218	24,270
Fair Value [Member] | One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term Debt, Fair Value	24,162	24,210
Fair Value [Member] | Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Long-term Debt, Fair Value	$ 58,905	$ 60,334

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Disclosures at Fair Value Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments Net Asset Value	$ 37,300	$ 23,700
Debt Securities, Available-for-sale	5,273,100	5,162,522
Equity securities	147,639
Equity securities, AFS		182,705
Total AFS securities		5,345,227
Short-term investments	323,864	165,555
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	5,273,100	5,162,522
Equity securities	147,639
Equity securities, AFS		182,705
Total AFS securities		5,345,227
Short-term investments	323,864	165,555
Total Assets	5,744,603	5,510,782
U.S. Government and Government Agencies and Authorities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	121,310	49,740
Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	23,131	18,555
Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,138,469	1,582,970
Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,617,408	1,617,468
Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	717,362	795,458
Commercial Mortgage-backed Securities (CMBS) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	527,078	383,449
Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,128,342	714,882
Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	144,727
Equity securities, AFS		167,757
Nonredeemable Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	2,912
Equity securities, AFS		14,948
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	78,381	24,652
Equity securities	110,309
Equity securities, AFS		153,588
Total AFS securities		178,240
Short-term investments	321,370	165,555
Total Assets	510,060	343,795
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | U.S. Government and Government Agencies and Authorities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	78,381	24,652
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Commercial Mortgage-backed Securities (CMBS) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	107,397
Equity securities, AFS		138,640
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Nonredeemable Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	2,912
Equity securities, AFS		14,948
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	5,187,310	5,131,316
Equity securities	0
Equity securities, AFS		0
Total AFS securities		5,131,316
Short-term investments	2,494	0
Total Assets	5,189,804	5,131,316
Significant Other Observable Inputs (Level 2) [Member] | U.S. Government and Government Agencies and Authorities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	42,929	25,088
Significant Other Observable Inputs (Level 2) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	23,131	18,555
Significant Other Observable Inputs (Level 2) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,138,469	1,582,970
Significant Other Observable Inputs (Level 2) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,617,408	1,617,468
Significant Other Observable Inputs (Level 2) [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	709,953	795,458
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage-backed Securities (CMBS) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	527,078	376,895
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,128,342	714,882
Significant Other Observable Inputs (Level 2) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0
Equity securities, AFS		0
Significant Other Observable Inputs (Level 2) [Member] | Nonredeemable Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0
Equity securities, AFS		0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	7,409	6,554
Equity securities	0
Equity securities, AFS		5,398
Total AFS securities		11,952
Short-term investments	0	0
Total Assets	7,409	11,952
Significant Unobservable Inputs (Level 3) [Member] | U.S. Government and Government Agencies and Authorities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	7,409	0
Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage-backed Securities (CMBS) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	6,554
Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0
Equity securities, AFS		5,398
Significant Unobservable Inputs (Level 3) [Member] | Nonredeemable Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 0
Equity securities, AFS		$ 0

Fair Value Measurements (Change

Fair Value Measurements (Changes in Fair Value of Securities Using Level 3 Inputs) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	$ 11,952
Total net (losses) gains for the period included in OCI	0
Total net (losses) gains for the period included in net income	0
Purchases	7,409
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	(11,952)
Fair Value, Ending Balance	7,409
Common Stock [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	5,398
Total net (losses) gains for the period included in OCI	0
Total net (losses) gains for the period included in net income	0
Purchases	0
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	(5,398)
Fair Value, Ending Balance	0
AFS Fixed Income Securities [Member] | Commercial Mortgage-backed Securities (CMBS) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	6,554
Total net (losses) gains for the period included in OCI	0
Total net (losses) gains for the period included in net income	0
Purchases	0
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	(6,554)
Fair Value, Ending Balance	0
AFS Fixed Income Securities [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	0
Total net (losses) gains for the period included in OCI	0
Total net (losses) gains for the period included in net income	0
Purchases	7,409
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	0
Fair Value, Ending Balance	$ 7,409

Fair Value Measurements (Quan_2

Fair Value Measurements (Quantitative Information of Our Financial Assets and Liabilities That Were Disclosed at Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	$ 38,317	$ 44,100
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	0	0
Long-term Debt, Fair Value	177,230	186,332
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	38,317	38,567
Long-term Debt, Fair Value	271,392	286,802
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	0	5,533
Long-term Debt, Fair Value	0	0
Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	17,969	26,261
Obligations of States and Political Subdivisions [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	0	0
Obligations of States and Political Subdivisions [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	17,969	26,261
Obligations of States and Political Subdivisions [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	0	0
Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	20,348	17,839
Corporate Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	0	0
Corporate Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	20,348	12,306
Corporate Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total HTM fixed income securities fair value	0	5,533
Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	57,032	61,391
Seven Point Twenty Five Percent Senior Notes [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Seven Point Twenty Five Percent Senior Notes [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	57,032	61,391
Seven Point Twenty Five Percent Senior Notes [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Six Point Seventy Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	107,075	116,597
Six Point Seventy Percent Senior Notes [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Six Point Seventy Percent Senior Notes [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	107,075	116,597
Six Point Seventy Percent Senior Notes [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Five Point Eight Hundred Seventy Five Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	177,230	186,332
Five Point Eight Hundred Seventy Five Percent Senior Notes [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	177,230	186,332
Five Point Eight Hundred Seventy Five Percent Senior Notes [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Five Point Eight Hundred Seventy Five Percent Senior Notes [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	24,218	24,270
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	24,218	24,270
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	24,162	24,210
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	24,162	24,210
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	58,905	60,334
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	58,905	60,334
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Long-term Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	$ 448,622	$ 473,134

Reinsurance (Total Reinsurance

Reinsurance (Total Reinsurance Balances Segregated By Reinsurer) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Terrorism Risk Insurance Program Companys Estimated Deductible		$ 339,000
Terrorism Risk Insurance Program Reimbursed Percentage Maximum		81.00%
Terrorism Risk Insurance Program Annual Cap		$ 100,000,000
Terrorism Risk Insurance Program Insurer Retainer		19.00%
Terrorism Risk Insurance Program Reimbursed Percentage Minimum		80.00%
Allowance For Reinsurance Recoverable		$ 13,900	$ 14,600	$ 11,480	$ 10,122
Total reinsurance recoverables		549,172	594,832
Total prepaid reinsurance premiums		157,723	153,493
Net unsecured reinsurance balances		706,895	748,325
Less: collateral	[1]	(112,201)	(122,413)
National Flood Insurance Program [Member]
Net unsecured reinsurance balances	[2]	$ 170,453	$ 204,161
% of Net Unsecured Reinsurance	[2]	24.00%	27.00%
NJ Unsatisfied Claim Judgment Fund [Member]
Net unsecured reinsurance balances	[2]	$ 55,167	$ 62,947
% of Net Unsecured Reinsurance	[2]	7.00%	9.00%
Other Federal And State Pools [Member]
Net unsecured reinsurance balances	[2]	$ 3,602	$ 3,634
% of Net Unsecured Reinsurance	[2]	1.00%	0.00%
Total Federal And State Pools [Member]
Net unsecured reinsurance balances	[2]	$ 229,222	$ 270,742
% of Net Unsecured Reinsurance	[2]	32.00%	36.00%
Remaining Unsecured Reinsurance [Member]
Net unsecured reinsurance balances		$ 477,673	$ 477,583
% of Net Unsecured Reinsurance		68.00%	64.00%
Munich Re Group [Member]
Net unsecured reinsurance balances		$ 112,841	$ 117,460
% of Net Unsecured Reinsurance		16.00%	16.00%
Hanover Ruckversicherungs AG [Member]
Net unsecured reinsurance balances		$ 101,835	$ 101,652
% of Net Unsecured Reinsurance		14.00%	14.00%
AXIS Reinsurance Company [Member]
Net unsecured reinsurance balances		$ 69,102	$ 62,396
% of Net Unsecured Reinsurance		10.00%	8.00%
Swiss Re Group [Member]
Net unsecured reinsurance balances		$ 37,519	$ 40,772
% of Net Unsecured Reinsurance		5.00%	5.00%
Transatlantic Reinsurance Company [Member]
Net unsecured reinsurance balances		$ 17,686	$ 13,237
% of Net Unsecured Reinsurance		3.00%	2.00%
Endurance Specialty Ins LTD [Member]
Net unsecured reinsurance balances		$ 15,163	$ 18,469
% of Net Unsecured Reinsurance		2.00%	2.00%
Partner Reinsurance Company Of The US [Member]
Net unsecured reinsurance balances		$ 12,261	$ 16,925
% of Net Unsecured Reinsurance		2.00%	2.00%
All Other Reinsurers [Member]
Net unsecured reinsurance balances		$ 111,266	$ 106,672
% of Net Unsecured Reinsurance		16.00%	15.00%
Remaining Unsecured Reinsurance, Net of Collateral [Member]
Net unsecured reinsurance balances		$ 365,472	$ 355,170
SEC Schedule, 12-09, Allowance, Reinsurance Recoverable [Member]
Allowance For Reinsurance Recoverable		$ 4,500	$ 4,600
[1]	2Includes letters of credit, trust funds, and funds held against reinsurance recoverables.
[2]	1Considered to have minimal risk of default.

Reinsurance (List of direct, as

Reinsurance (List of direct, assumed and ceded Reinsurance Amounts) (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Premiums Written:
Direct											$ 2,890,633	$ 2,733,459	$ 2,577,259
Assumed											26,250	26,685	28,779
Ceded premiums written											(402,597)	(389,503)	(368,750)
Net											2,514,286	2,370,641	2,237,288
Premiums Earned:
Direct											2,808,764	2,647,488	2,484,715
Assumed											25,831	25,831	28,214
Ceded premiums earned											(398,366)	(382,292)	(363,357)
Total Net Premiums Earned	$ 625,288		$ 614,277	$ 604,836	$ 591,828	$ 590,088		$ 572,055	$ 568,030	$ 560,854	2,436,229	2,291,027	2,149,572
Loss and loss expense incurred:
Direct											1,706,951	1,570,678	1,560,356
Assumed											21,469	17,588	22,708
Ceded loss and loss expense											(230,286)	(243,192)	(348,267)
Net											$ 1,498,134	$ 1,345,074	$ 1,234,797
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Reinsurance (Ceded Premiums and

Reinsurance (Ceded Premiums and Losses Related to Flood Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Percentage of NFIP claims ceded to the federal government	100.00%
Ceded premiums written	$ (402,597)	$ (389,503)	$ (368,750)
Ceded premiums earned	(398,366)	(382,292)	(363,357)
Ceded loss and loss expense	(230,286)	(243,192)	(348,267)
National Flood Insurance Program [Member]
Ceded premiums written	(248,053)	(241,345)	(232,245)
Ceded premiums earned	(244,238)	(235,088)	(227,882)
Ceded loss and loss expense	$ (144,967)	$ (160,922)	$ (239,891)

Reserve for Loss and Loss Exp_3

Reserve for Loss and Loss Expense (Rollforward of Reserve for Loss and Loss Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gross reserve for loss and loss expense, at beginning of year	$ 3,771,240	$ 3,691,719	$ 3,517,728
Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of year	585,855	611,200	551,019
Net reserve for loss and loss expense, at beginning of year	3,185,385	3,080,519	2,966,709
Incurred loss and loss expense for claims occurring in the current year	1,527,997	1,384,266	1,300,565
Incurred loss and loss expense for claims occurring in the prior years	(29,863)	(39,192)	(65,768)
Total incurred loss and loss expense	1,498,134	1,345,074	1,234,797
Paid loss and loss expense for claims occurring in current year	573,718	497,486	450,811
Paid loss and loss expense for claims occurring in prior years	753,321	742,722	670,176
Total paid loss and loss expense	1,327,039	1,240,208	1,120,987
Net reserve for loss and loss expense, at end of year	3,356,480	3,185,385	3,080,519
Add: reinsurance recoverable on unpaid loss and loss expense, at end of year	537,388	585,855	611,200
Gross reserve for loss and loss expense, at end of year	3,893,868	3,771,240	3,691,719
Increase of net loss and loss expense reserves	171,100	104,900	113,800
Anticipated recoveries for salvage and subrogation claims	$ 67,700	$ 64,800	$ 64,900

Reserve for Loss and Loss Exp_4

Reserve for Loss and Loss Expense (Reserve Loss Development) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years	$ 753,321	$ 742,722	$ 670,176
Favorable or adverse loss development	(29,863)	(39,192)	(65,768)
Favorable or unfavorable loss development [Member]
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years	29,900	39,200	65,800
Favorable or adverse loss development	(29,900)	(39,200)	(65,800)
Favorable or unfavorable loss development [Member] | Casualty Insurance Product Line [Member]
Favorable or adverse loss development	41,500	48,600	69,000
Favorable or unfavorable loss development [Member] | Property Insurance Product Line [Member]
Favorable or adverse loss development	11,600	9,400	3,200
Favorable or unfavorable loss development [Member] | General Liability [Member]
Favorable or adverse loss development	(9,500)	(48,300)	(45,000)
Favorable or unfavorable loss development [Member] | Commercial Automobile [Member]
Favorable or adverse loss development	36,700	35,600	25,300
Casualty Development	37,500	36,000	25,000
Favorable or unfavorable loss development [Member] | Workers Compensation [Member]
Favorable or adverse loss development	(83,000)	(52,300)	(56,000)
Favorable or unfavorable loss development [Member] | Business Owners' Policies [Member]
Favorable or adverse loss development	(1,500)	1,900	1,800
Favorable or unfavorable loss development [Member] | Commercial Property [Member]
Favorable or adverse loss development	7,500	8,700	300
Favorable or unfavorable loss development [Member] | Homeowners [Member]
Favorable or adverse loss development	9,800	400	1,700
Favorable or unfavorable loss development [Member] | Personal Automobile [Member]
Favorable or adverse loss development	3,000	6,700	1,000
Favorable or unfavorable loss development [Member] | E&S Casualty Lines [Member]
Favorable or adverse loss development	12,000	10,000	6,000
Favorable or unfavorable loss development [Member] | E&S Property Lines [Member]
Favorable or adverse loss development	(4,800)	100	1,200
Favorable or unfavorable loss development [Member] | Other Insurance Product Line [Member]
Favorable or adverse loss development	$ (100)	$ (2,000)	$ (2,100)

Reserve for Loss and Loss Exp_5

Reserve for Loss and Loss Expense (Exposure to Environmental Claims) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss and Loss expense reserves, Gross	$ 30,020	$ 28,415	$ 29,962	$ 30,411
Liability for Asbestos and Environmental Claims, Net	22,783	$ 21,212	$ 22,716	$ 23,161
Asbestos Claim [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss and Loss expense reserves, Gross	7,300
Liability for Asbestos and Environmental Claims, Net	6,100
Landfill Sites Related Claims [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss and Loss expense reserves, Gross	12,200
Liability for Asbestos and Environmental Claims, Net	7,400
Leaking Underground Storage Tanks Claims [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss and Loss expense reserves, Gross	10,500
Liability for Asbestos and Environmental Claims, Net	$ 9,300

Reserve for Loss and Loss Exp_6

Reserve for Loss and Loss Expense (Roll Forward of Gross and Net Asbestos and Net Environmental Incurred Losses and Loss Expenses and Related Reserves) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for loss and loss expense at beginning of year, gross	$ 28,415	$ 29,962	$ 30,411
Incurred loss and loss expense, gross	3,059	126	1,483
Less: loss and loss expense paid, gross	(1,454)	(1,673)	(1,932)
Reserve for loss and loss expense at the end of year, gross	30,020	28,415	29,962
Reserve for loss and loss expense at beginning of year, net	21,212	22,716	23,161
Incurred loss and loss expense, net	2,877	0	1,380
Less: loss and loss expense paid, net	(1,306)	(1,504)	(1,825)
Reserve for loss and loss expense at the end of year, net	22,783	21,212	22,716
Asbestos [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for loss and loss expense at beginning of year, gross	7,577	7,847	8,024
Incurred loss and loss expense, gross	0	0	(77)
Less: loss and loss expense paid, gross	(249)	(270)	(254)
Reserve for loss and loss expense at the end of year, gross	7,328	7,577	7,847
Reserve for loss and loss expense at beginning of year, net	6,346	6,615	6,793
Incurred loss and loss expense, net	0	0	77
Less: loss and loss expense paid, net	(249)	(269)	(255)
Reserve for loss and loss expense at the end of year, net	6,097	6,346	6,615
Enviromental [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for loss and loss expense at beginning of year, gross	20,838	22,115	22,387
Incurred loss and loss expense, gross	3,059	126	1,406
Less: loss and loss expense paid, gross	(1,205)	(1,403)	(1,678)
Reserve for loss and loss expense at the end of year, gross	22,692	20,838	22,115
Reserve for loss and loss expense at beginning of year, net	14,866	16,101	16,368
Incurred loss and loss expense, net	2,877	0	1,303
Less: loss and loss expense paid, net	(1,057)	(1,235)	(1,570)
Reserve for loss and loss expense at the end of year, net	$ 16,686	$ 14,866	$ 16,101

Reserve for Loss and Loss Exp_7

Reserve for Loss and Loss Expense Reserve for Loss and Loss Expense (Claims Development) (Details)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)	Dec. 31, 2009USD ($)
Claims Development [Line Items]
Net outstanding liabilities	$ 10,921,712,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	8,066,344,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	3,216,999,000
Reserve for loss and loss expense	3,893,868,000	$ 3,771,240,000
Short-duration Insurance Contracts, Accident Year 2009 [Member]
Claims Development [Line Items]
Net outstanding liabilities	846,017,000	848,413,000	$ 853,401,000	$ 857,960,000	$ 869,927,000	$ 870,057,000	$ 883,590,000	$ 916,691,000	$ 941,972,000	$ 920,143,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 34,771,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	85,707
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 791,281,000	784,713,000	775,885,000	760,589,000	736,100,000	695,249,000	634,902,000	540,982,000	442,417,000	277,275,000
Short-duration Insurance Contracts, Accident Year 2010 [Member]
Claims Development [Line Items]
Net outstanding liabilities	904,561,000	907,074,000	915,131,000	922,404,000	943,118,000	956,600,000	977,959,000	973,742,000	950,114,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 42,224,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	94,400
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 846,386,000	835,532,000	823,770,000	803,773,000	773,536,000	704,895,000	625,229,000	509,910,000	328,826,000
Short-duration Insurance Contracts, Accident Year 2011 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,013,115,000	1,019,351,000	1,023,726,000	1,033,518,000	1,056,107,000	1,062,233,000	1,061,667,000	1,042,576,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 50,251,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	104,677
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 940,626,000	924,111,000	901,801,000	852,202,000	782,655,000	692,730,000	585,867,000	391,944,000
Short-duration Insurance Contracts, Accident Year 2012 [Member]
Claims Development [Line Items]
Net outstanding liabilities	973,411,000	973,644,000	973,089,000	998,028,000	1,020,655,000	1,071,290,000	1,065,437,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 66,071,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	103,949
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 879,372,000	856,195,000	810,135,000	743,742,000	651,544,000	555,819,000	378,067,000
Short-duration Insurance Contracts, Accident Year 2013 [Member]
Claims Development [Line Items]
Net outstanding liabilities	987,763,000	1,002,316,000	1,021,007,000	1,047,230,000	1,062,045,000	1,044,142,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 86,250,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	91,084
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 872,331,000	833,823,000	748,758,000	644,475,000	518,872,000	335,956,000
Short-duration Insurance Contracts, Accident Year 2014 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,104,218,000	1,124,014,000	1,146,990,000	1,133,798,000	1,107,513,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 117,760,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	94,774
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 936,425,000	855,959,000	736,154,000	614,075,000	405,898,000
Short-duration Insurance Contracts, Accident Year 2015 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,138,313,000	1,144,830,000	1,130,513,000	1,114,081,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 175,271,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	93,673
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 845,868,000	725,385,000	581,203,000	376,641,000
Short-duration Insurance Contracts, Accident Year 2016 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,227,142,000	1,203,634,000	1,188,608,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 319,825,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	93,724
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 764,331,000	617,958,000	387,272,000
Short-duration Insurance Contracts, Accident Year 2017 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,313,372,000	1,270,110,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 471,978,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	96,426
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 678,453,000	433,440,000
Short-duration Insurance Contracts, Accident Year 2018 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,413,800,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 677,444,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	96,408
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 511,271,000
Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	361,631,000
Standard Commercial Lines [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	2,361,691,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,277,379,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	1,175,230,000
Standard Commercial Lines [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,844,096,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,216,045,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	873,882,000
Standard Commercial Lines [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	2,340,518,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,812,040,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	532,320,000
Standard Commercial Lines [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	499,967,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	422,006,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	85,744,000
Standard Commercial Lines [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,222,005,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,163,094,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	58,980,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	203,176,000	201,568,000	205,741,000	206,387,000	211,243,000	212,947,000	223,146,000	233,530,000	241,625,000	237,913,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 15,951,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	13,873
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 183,263,000	180,621,000	176,316,000	166,767,000	151,920,000	130,554,000	103,213,000	64,970,000	37,143,000	14,346,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	205,125,000	208,142,000	208,611,000	212,536,000	216,992,000	210,756,000	210,109,000	213,036,000	215,946,000	197,504,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 18,242,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	12,218
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 171,205,000	167,894,000	164,336,000	160,529,000	154,726,000	145,417,000	133,116,000	117,019,000	87,299,000	37,885,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	161,057,000	161,300,000	161,923,000	161,251,000	162,911,000	166,682,000	169,858,000	182,724,000	191,079,000	199,541,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 574,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	24,749
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 160,456,000	160,013,000	159,723,000	158,303,000	155,560,000	149,949,000	137,564,000	113,697,000	94,406,000	63,126,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	44,028,000	43,933,000	44,273,000	44,299,000	44,938,000	43,553,000	43,828,000	46,645,000	51,762,000	48,535,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 323,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,474
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 43,596,000	43,547,000	43,448,000	43,358,000	42,895,000	40,052,000	36,073,000	32,689,000	29,612,000	18,915,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	80,410,000	80,416,000	80,545,000	80,558,000	80,455,000	80,774,000	82,014,000	82,025,000	82,124,000	82,619,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,009
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 80,393,000	80,405,000	80,509,000	80,529,000	80,352,000	80,251,000	80,894,000	80,433,000	78,695,000	59,933,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	206,146,000	202,394,000	208,968,000	211,619,000	222,328,000	237,154,000	242,499,000	228,680,000	215,208,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 18,634,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	12,696
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 183,988,000	178,179,000	172,394,000	161,487,000	143,360,000	113,050,000	80,018,000	46,201,000	15,726,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	199,539,000	204,423,000	208,155,000	212,448,000	214,916,000	211,030,000	212,815,000	214,469,000	198,371,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 22,614,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	12,185
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 165,526,000	162,796,000	158,078,000	153,795,000	149,086,000	137,184,000	122,442,000	93,281,000	46,795,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	173,080,000	173,471,000	173,157,000	172,969,000	179,854,000	181,923,000	187,778,000	189,305,000	187,562,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 762,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	25,406
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 171,693,000	169,793,000	169,100,000	167,227,000	163,513,000	146,913,000	128,015,000	99,254,000	68,098,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	40,920,000	41,197,000	41,239,000	40,581,000	40,899,000	39,915,000	42,408,000	49,285,000	53,669,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 381,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,918
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 40,439,000	40,395,000	40,279,000	38,900,000	37,819,000	34,705,000	31,027,000	28,131,000	20,821,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	95,142,000	95,155,000	95,178,000	95,363,000	95,530,000	96,127,000	97,386,000	96,851,000	105,647,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 4,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,668
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 95,138,000	95,150,000	95,156,000	95,147,000	95,270,000	95,111,000	94,602,000	91,918,000	69,543,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	211,500,000	212,011,000	211,196,000	217,256,000	230,785,000	239,480,000	228,720,000	227,769,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 20,973,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,614
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 181,856,000	170,525,000	159,768,000	135,377,000	102,978,000	73,643,000	42,692,000	13,924,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	194,821,000	200,674,000	205,708,000	210,591,000	215,114,000	214,743,000	218,973,000	205,238,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 26,226,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,850
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 158,535,000	154,320,000	149,269,000	139,232,000	134,646,000	118,847,000	90,836,000	42,941,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	173,507,000	174,514,000	174,882,000	172,617,000	178,421,000	182,325,000	183,044,000	174,006,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,633,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	25,398
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 170,913,000	170,000,000	166,082,000	157,291,000	142,507,000	121,576,000	99,196,000	69,849,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	58,735,000	58,456,000	58,966,000	59,256,000	58,242,000	51,047,000	57,083,000	54,469,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,140,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	4,959
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 57,365,000	57,045,000	55,856,000	52,114,000	46,444,000	41,011,000	37,362,000	27,884,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	131,009,000	131,049,000	131,113,000	131,353,000	131,282,000	130,942,000	131,667,000	136,954,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	9,038
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 131,100,000	131,089,000	131,115,000	131,060,000	130,681,000	129,579,000	127,580,000	94,538,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	180,659,000	175,268,000	175,305,000	194,144,000	215,083,000	245,561,000	238,979,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 25,251,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	9,960
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 144,451,000	130,866,000	109,448,000	89,008,000	56,580,000	35,241,000	13,030,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	183,314,000	187,359,000	188,596,000	195,197,000	199,360,000	208,036,000	203,864,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 30,444,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,613
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 143,281,000	139,477,000	132,052,000	122,755,000	108,211,000	86,909,000	40,911,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	184,633,000	186,128,000	184,367,000	184,289,000	183,527,000	191,947,000	179,551,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,259,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	24,025
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 179,501,000	176,656,000	168,114,000	148,669,000	127,235,000	105,371,000	73,316,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	43,418,000	43,747,000	44,077,000	44,172,000	46,303,000	48,029,000	54,342,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 430,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,542
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 41,326,000	40,627,000	38,766,000	37,215,000	35,089,000	31,833,000	22,199,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	117,225,000	117,170,000	117,102,000	116,658,000	115,375,000	114,224,000	118,464,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 21,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,515
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 116,671,000	116,625,000	116,291,000	114,699,000	111,503,000	108,834,000	81,528,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	203,831,000	210,785,000	225,709,000	239,776,000	251,421,000	250,609,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 35,971,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,326
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 153,628,000	139,114,000	104,587,000	72,127,000	35,113,000	12,789,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	162,787,000	166,662,000	173,160,000	187,658,000	194,318,000	199,794,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 30,648,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,372
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 124,130,000	118,669,000	109,739,000	96,376,000	74,568,000	36,829,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	207,975,000	210,410,000	207,994,000	209,197,000	205,282,000	188,289,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 3,756,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	25,556
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 200,750,000	189,626,000	169,850,000	140,015,000	109,893,000	76,469,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	39,709,000	41,369,000	40,624,000	41,005,000	42,618,000	49,617,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,404,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,482
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 38,464,000	37,993,000	34,760,000	30,845,000	26,592,000	17,412,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	90,278,000	90,436,000	90,005,000	90,103,000	90,639,000	88,101,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 28,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,713
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 90,696,000	90,840,000	90,350,000	90,446,000	87,874,000	60,244,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	234,082,000	239,333,000	257,132,000	249,946,000	244,312,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 57,041,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,513
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 154,957,000	121,969,000	79,972,000	46,825,000	14,901,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	164,420,000	172,515,000	182,579,000	187,065,000	199,346,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 33,422,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,488
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 119,392,000	113,626,000	100,876,000	78,944,000	35,924,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	218,172,000	219,925,000	216,824,000	212,725,000	200,534,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 8,718,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	27,528
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 202,821,000	180,701,000	148,884,000	117,169,000	80,810,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	58,517,000	59,806,000	62,548,000	60,949,000	55,962,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,959,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	4,062
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 52,940,000	49,460,000	44,911,000	40,584,000	28,914,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	138,155,000	138,751,000	136,820,000	136,249,000	141,192,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 57,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,514
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 137,418,000	137,883,000	136,634,000	132,909,000	101,131,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	233,249,000	246,990,000	245,710,000	254,720,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 84,861,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,253
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 116,804,000	78,668,000	39,978,000	14,665,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	179,642,000	183,604,000	194,639,000	193,729,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 34,940,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,544
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 112,601,000	98,195,000	77,320,000	33,857,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	259,495,000	253,074,000	240,958,000	220,994,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 19,192,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	29,092
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 211,515,000	175,866,000	132,260,000	91,347,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	55,925,000	57,245,000	53,768,000	52,871,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,215,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,952
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 46,571,000	42,710,000	36,014,000	24,189,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	111,566,000	111,750,000	109,513,000	110,270,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 77,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,401
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 110,994,000	109,829,000	106,182,000	79,048,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	277,986,000	272,048,000	277,214,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 142,991,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,213
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 89,431,000	46,549,000	15,684,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	176,248,000	184,946,000	196,774,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 56,258,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,553
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 98,037,000	78,531,000	34,525,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	285,302,000	274,367,000	255,187,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 46,407,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	30,855
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 200,701,000	155,720,000	106,022,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	54,993,000	53,792,000	52,335,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 9,272,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,823
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 39,973,000	36,848,000	24,655,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	125,937,000	126,185,000	121,927,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 405,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,727
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 122,930,000	118,789,000	83,966,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	293,128,000	293,747,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 202,925,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,032
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 49,470,000	17,366,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	184,306,000	195,202,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 72,213,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,745
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 82,216,000	40,375,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	329,389,000	301,274,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 98,125,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	32,122
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 178,823,000	117,287,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	48,698,000	46,624,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 13,087,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,808
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 31,337,000	21,865,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	149,106,000	138,773,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ (76,000)
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,850
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 142,338,000	99,047,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	317,934,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 270,267,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,741
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 19,531,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	193,894,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 98,015,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,553
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 41,122,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	347,908,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 164,906,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	32,895
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 134,867,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	55,024,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 16,177,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,823
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 29,995,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	183,177,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 7,052,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,695
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 135,416,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | General Liability [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	90,918,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	245,831,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	3,842,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	7,783,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	69,000
Standard Personal Lines [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,064,912,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	974,882,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	96,070,000
Standard Personal Lines [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	707,712,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	682,713,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	31,106,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	103,303,000	103,348,000	103,412,000	103,393,000	103,866,000	104,734,000	103,908,000	105,033,000	103,319,000	93,808,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 146,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	17,346
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 103,010,000	103,009,000	102,437,000	102,322,000	102,187,000	100,566,000	96,229,000	86,431,000	71,911,000	51,039,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	40,500,000	40,451,000	40,457,000	40,465,000	40,400,000	61,927,000	40,313,000	42,609,000	44,511,000	47,636,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 70,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,634
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 40,403,000	40,269,000	40,189,000	39,907,000	39,819,000	39,731,000	39,342,000	38,078,000	36,965,000	$ 28,299,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	106,887,000	107,054,000	107,224,000	107,405,000	107,490,000	109,515,000	112,346,000	110,075,000	103,340,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 160,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,822
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 106,722,000	106,733,000	106,453,000	105,849,000	104,061,000	101,540,000	95,300,000	82,490,000	58,786,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	62,402,000	62,392,000	62,339,000	62,402,000	62,462,000	97,761,000	63,285,000	67,525,000	68,373,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 83,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	9,132
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 62,283,000	62,272,000	62,241,000	62,227,000	62,155,000	61,106,000	60,295,000	58,638,000	$ 43,699,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	113,921,000	113,988,000	113,830,000	114,241,000	112,993,000	113,686,000	116,164,000	113,232,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 194,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,700
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 113,664,000	113,551,000	112,732,000	111,085,000	105,068,000	93,878,000	82,102,000	61,323,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	94,587,000	94,378,000	94,183,000	94,543,000	94,167,000	82,744,000	98,211,000	103,804,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 131,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	15,109
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 94,412,000	94,007,000	93,720,000	93,312,000	92,185,000	91,718,000	89,963,000	71,668,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	109,795,000	110,300,000	110,294,000	109,324,000	109,832,000	114,921,000	113,771,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 205,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,332
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 109,447,000	109,355,000	107,890,000	102,977,000	94,842,000	82,729,000	63,704,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	86,483,000	86,330,000	86,271,000	86,667,000	86,560,000	82,745,000	87,260,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 237,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	16,939
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 85,642,000	85,562,000	85,196,000	84,250,000	82,720,000	79,584,000	69,056,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	107,680,000	107,759,000	106,703,000	106,225,000	109,620,000	108,417,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 288,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,373
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 106,679,000	105,131,000	100,528,000	92,637,000	80,861,000	61,384,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	72,148,000	71,714,000	72,145,000	71,494,000	72,528,000	73,670,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 331,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,747
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 72,197,000	71,776,000	69,775,000	67,838,000	65,528,000	50,664,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	106,821,000	107,452,000	106,757,000	109,325,000	102,250,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 774,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,504
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 104,055,000	99,173,000	92,589,000	83,739,000	62,519,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	83,539,000	83,844,000	83,637,000	82,461,000	80,111,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 411,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,770
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 82,583,000	81,664,000	79,751,000	76,007,000	61,561,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	99,570,000	100,214,000	99,698,000	96,387,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,572,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,860
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 92,102,000	87,163,000	76,470,000	58,725,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	74,723,000	76,559,000	76,400,000	76,637,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,172,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,744
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 72,927,000	72,202,000	70,078,000	52,589,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	100,202,000	98,032,000	92,727,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,252,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	19,803
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 86,752,000	76,823,000	57,961,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	62,391,000	60,931,000	60,105,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,837,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,869
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 59,546,000	57,333,000	42,252,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	105,139,000	101,880,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 13,162,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,679
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 82,730,000	62,854,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	67,978,000	59,167,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,969,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,299
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 63,290,000	45,466,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	111,594,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 23,506,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	21,748
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 69,721,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	62,961,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,660,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,062
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 49,430,000
Standard Personal Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	6,040,000
Standard Personal Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Homeowners [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	6,107,000
E&S Lines [Member]
Claims Development [Line Items]
Reserve for loss and loss expense								15,000,000
E&S Lines [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	593,898,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	263,529,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	330,467,000
E&S Lines [Member] | Commercial Property [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	13,604,000
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	739,000	737,000	96,000	710,000	728,000	938,000	1,053,000	885,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Short-duration Insurance Contract, Cumulative Number of Reported Claims	274
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 739,000	737,000	709,000	626,000	605,000	431,000	198,000	0
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	5,168,000	4,932,000	3,055,000	3,831,000	4,299,000	3,369,000	4,106,000	3,294,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Short-duration Insurance Contract, Cumulative Number of Reported Claims	813
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 4,908,000	4,610,000	4,513,000	4,078,000	3,574,000	2,570,000	1,218,000	0
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	12,119,000	10,228,000	9,652,000	10,273,000	12,207,000	9,853,000	7,102,000	8,127,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 276,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	1,321
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 9,819,000	10,256,000	9,912,000	9,954,000	6,445,000	3,200,000	806,000	$ 0
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	46,444,000	45,988,000	46,165,000	46,149,000	43,175,000	42,621,000	42,367,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,417,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,022
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 38,298,000	36,278,000	32,343,000	25,064,000	16,430,000	7,914,000	$ 3,722,000
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	68,972,000	67,647,000	69,112,000	67,099,000	60,309,000	55,468,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 14,175,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,266
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 51,142,000	46,108,000	35,200,000	21,980,000	9,470,000	$ 2,715,000
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	71,206,000	71,719,000	69,929,000	63,505,000	55,316,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 14,097,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,040
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 53,780,000	43,877,000	25,571,000	12,234,000	$ 2,353,000
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	90,488,000	82,404,000	76,432,000	75,498,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 24,516,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,746
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 50,712,000	29,389,000	13,057,000	$ 3,036,000
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	104,655,000	96,416,000	94,451,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 52,151,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,732
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 33,950,000	16,195,000	$ 3,720,000
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	95,783,000	91,438,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 66,321,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,353
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 14,672,000	$ 5,057,000
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	98,324,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 82,486,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	1,734
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 5,509,000
E&S Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | General Liability [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	$ 98,000

Reserve for Loss and Loss Exp_8

Reserve for Loss and Loss Expense Reserve for Loss and Loss Expense (Reconciliation of Claims Development to Liability) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net outstanding liabilities	$ 1,498,134	$ 1,345,074	$ 1,234,797
Liability for Unpaid Claims and Claims Adjustment Expense, Net	3,216,999
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	537,388	585,855	611,200	$ 551,019
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claims Adjustment Expense, Accumulated Unallocated Claim Adjustment Expense	139,481
Liability for Claims and Claims Adjustment Expense	3,893,868	$ 3,771,240	$ 3,691,719	$ 3,517,728
General Liability [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	1,175,230
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	181,102
General Liability [Member] | E&S Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	330,467
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	21,898
Workers Compensation [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	873,882
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	220,683
Commercial Automobile [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	532,320
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	15,641
Business Owners' Policies [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	85,744
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	3,473
Commercial Property [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	58,980
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	12,620
Commercial Property [Member] | E&S Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	13,604
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	367
Other Commercial [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	9,122
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	2,909
Total Standard Commercial Lines [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	2,735,278
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	436,428
Personal Automobile [Member] | Standard Personal Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	96,070
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	45,572
Homeowners [Member] | Standard Personal Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	31,106
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	1,346
Other Personal [Member] | Standard Personal Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	10,474
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	31,777
Standard Personal Lines [Member] | Standard Personal Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	137,650
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	78,695
Total E&S Lines [Member] | E&S Lines [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	344,071
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	$ 22,265

Reserve for Loss and Loss Exp_9

Reserve for Loss and Loss Expense Reserve for Loss and Loss Expense (Historical Claims Duration) (Details)	Dec. 31, 2018
General Liability [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	6.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	12.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	15.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	17.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	14.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	9.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	6.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	4.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	2.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.10%
General Liability [Member] | E&S Lines [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	5.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	11.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	17.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	21.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	15.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	8.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	5.40%
Workers Compensation [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	21.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	24.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	13.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	8.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	5.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	3.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	2.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	2.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	1.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.10%
Commercial Automobile [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	37.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	17.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	14.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	13.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	9.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	1.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.40%
Business Owners' Policies [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	47.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	19.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	8.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	8.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	7.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	4.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	1.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.10%
Commercial Property [Member] | Standard Commercial Lines [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	70.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	25.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	2.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	1.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.00%
Personal Automobile [Member] | Standard Personal Lines [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	57.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	18.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	10.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	7.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	4.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	1.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.00%
Homeowners [Member] | Standard Personal Lines [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	72.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	20.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	3.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	1.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	1.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	0.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.10%

Indebtedness Indebtedness (Sche

Indebtedness Indebtedness (Schedule of Long-Term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Schedule of Debt Instruments [Line Items]
Debt Discount and Unamortized Issuance Costs	$ 0
Interest Rate	3.03%
Long-term Debt, Gross	$ 60,000
Long-term Debt	60,000	$ 60,000
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Schedule of Debt Instruments [Line Items]
Debt Discount and Unamortized Issuance Costs	$ 0
Interest Rate	1.56%
Long-term Debt, Gross	$ 25,000
Long-term Debt	25,000	25,000
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Schedule of Debt Instruments [Line Items]
Debt Discount and Unamortized Issuance Costs	$ 0
Interest Rate	1.61%
Long-term Debt, Gross	$ 25,000
Long-term Debt	25,000	25,000
Five Point Eight Hundred Seventy Five Percent Senior Notes [Member]
Schedule of Debt Instruments [Line Items]
Debt Discount and Unamortized Issuance Costs	$ (4,229)
Interest Rate	5.875%
Long-term Debt, Gross	$ 185,000
Long-term Debt	180,771	180,430
Six Point Seventy Percent Senior Notes [Member]
Schedule of Debt Instruments [Line Items]
Debt Discount and Unamortized Issuance Costs	$ (931)
Interest Rate	6.70%
Long-term Debt, Gross	$ 100,000
Long-term Debt	99,069	99,011
Seven Point Twenty Five Percent Senior Notes [Member]
Schedule of Debt Instruments [Line Items]
Debt Discount and Unamortized Issuance Costs	$ (300)
Interest Rate	7.25%
Long-term Debt, Gross	$ 50,000
Long-term Debt	49,700	49,675
Long-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Debt Discount and Unamortized Issuance Costs	(5,460)
Long-term Debt, Gross	445,000
Long-term Debt	$ 439,540	$ 439,116

Indebtedness (Narrative) (Detai

Indebtedness (Narrative) (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2005USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2013USD ($)	Dec. 31, 2004USD ($)
Federal Home Loan Bank Advances			$ 45,000
Maximum borrowing percentage		10.00%
Borrowing threshold of FHLBI		20
Net proceeds from the issuance			15,000
Five Point Eight Hundred Seventy Five Percent Senior Notes Due 2043 [Member]
Aggregate principal amount of notes				$ 185,000
Bond proceeds to Insurance Subsidiaries as capital				$ 57,100
Long-term Debt, Gross		$ 185,000
Interest Rate		5.875%
Redemption Of Seven Point Fifty Percent Junior Notes [Member]
Aggregate principal amount of notes					$ 100,000
Interest Rate					7.50%
Six Point Seventy Percent Senior Notes due 2035 [Member]
Acceleration of principal		$ 10,000
Aggregate principal amount of notes	$ 100,000
Discount for notes issued	$ 700
Effective yield	6.754%
Net proceeds from the issuance	$ 50,000
Long-term Debt, Gross		$ 100,000
Interest Rate		6.70%
Seven Point Twenty Five Percent Senior Notes due 2034 [Member]
Acceleration of principal		$ 10,000
Aggregate principal amount of notes						$ 50,000
Discount for notes issued						$ 100
Effective yield						7.27%
Bond proceeds to Insurance Subsidiaries as capital						$ 25,000
Long-term Debt, Gross		$ 50,000
Interest Rate		7.25%
Line of Credit expires Dec.1, 2020 [Member]
Line of credit borrowing capacity		$ 30,000
Line of credit, maximum borrowing capacity		50,000
Acceleration of principal		20,000
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term Debt, Gross		$ 25,000
Interest Rate		1.61%
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term Debt, Gross		$ 25,000
Interest Rate		1.56%
One Point Seventy Five Percent Borrowing From Federal Home Loan Bank Due March 20, 2018 [Member]
Federal Home Loan Bank Advances		$ 75,000
Federal Home Loan Bank, Advances, Interest Rate		1.75%
One Point Ninety Eight Percent Borrowing From Federal Home Loan Bank Due April 18, 2018 [Member]
Federal Home Loan Bank Advances		$ 55,000
Federal Home Loan Bank, Advances, Interest Rate		1.98%
Federal Home Loan Bank of Indianapolis [Member]
Aggregate investment in FHLBI		$ 2,800
Federal Home Loan Bank of New York [Member]
Aggregate investment in FHLBI		$ 2,700	$ 2,600

Indebtedness (Covenants in the

Indebtedness (Covenants in the Line of Credit) (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Consolidated net worth, required		$ 1,300,000
Statutory surplus, required		$ 750,000
Debt-to-capitalization ratio, required	[1]	35.00%
Consolidated net worth, actual		$ 1,791,802	$ 1,712,957	$ 1,531,370
Statutory surplus, actual		$ 1,768,400	$ 1,672,900
Debt-to-capitalization ratio, actual	[1]	19.70%
[1]	Calculated in accordance with Line of Credit agreement.

Segment Information (Narrative)

Segment Information (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting [Abstract]
Number of Operating Segments	4
Goodwill balance for our Standard Commercial Lines reporting unit	$ 7,849	$ 7,849
Percentage of net premiums written related to insurance policies written in New Jersey	19.00%

Segment Information (Revenue Fr

Segment Information (Revenue From Continuing Operations by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017	[1]	Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from External Customer [Line Items]
Net premiums earned	$ 625,288		$ 614,277		$ 604,836		$ 591,828		$ 590,088		$ 572,055		$ 568,030		$ 560,854		$ 2,436,229	$ 2,291,027	$ 2,149,572
Other income	1,542		2,538		3,179		2,179		2,190		1,994		3,291		3,241		9,438	10,716	8,881
Net investment income	54,109		52,443		45,553		43,231		42,587		40,446		41,430		37,419		195,336	161,882	130,754
Total net realized and unrealized (losses) gains	(37,935)	[2]	(4,787)	[2]	(1,652)	[2]	(10,549)	[2]	(1,128)	[2]	6,798	[2]	1,734	[2]	(1,045)	[2]	(54,923)	6,359	(4,937)
Total investment revenues																	140,413	168,241	125,817
Total revenues	$ 643,004		$ 664,471		$ 651,916		$ 626,689		$ 633,737		$ 621,293		$ 614,485		$ 600,469		2,586,080	2,469,984	2,284,270
Standard Commercial Lines [Member]
Revenue from External Customer [Line Items]
Other income																	8,180	9,488	7,782
Total revenues																	1,920,402	1,797,987	1,673,265
Standard Commercial Lines [Member] | Commercial Automobile [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	493,093	442,818	398,942
Standard Commercial Lines [Member] | Workers Compensation [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	317,616	317,982	308,233
Standard Commercial Lines [Member] | General Liability [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	616,187	569,217	527,859
Standard Commercial Lines [Member] | Commercial Property [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	329,660	311,932	293,438
Standard Commercial Lines [Member] | Business Owners' Policies [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	103,412	100,266	97,754
Standard Commercial Lines [Member] | Bonds Segment [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	33,991	29,086	23,227
Standard Commercial Lines [Member] | Other Commercial [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	18,263	17,198	16,030
Standard Personal Lines [Member]
Revenue from External Customer [Line Items]
Other income																	1,257	1,228	1,098
Total revenues																	305,698	290,929	281,705
Standard Personal Lines [Member] | Personal Automobile [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	168,250	153,147	142,876
Standard Personal Lines [Member] | Homeowners [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	128,961	129,699	130,973
Standard Personal Lines [Member] | Other Personal [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	7,230	6,855	6,758
Excess And Surplus Operations [Member]
Revenue from External Customer [Line Items]
Other income																	1	0	1
Total revenues																	219,567	212,827	203,483
Excess And Surplus Operations [Member] | Casualty Insurance Product Line [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	164,313	157,366	151,638
Excess And Surplus Operations [Member] | Property Insurance Product Line [Member]
Revenue from External Customer [Line Items]
Net premiums earned																	$ 55,253	$ 55,461	$ 51,844
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.
[2]	Effective January 1, 2018, changes in unrealized gains and losses on our equity portfolio are recognized in income through "Net unrealized losses on equity securities" on our Consolidated Statements of Income, as a result of our adoption of ASU 2016-01. See Note 3. "Adoption of Accounting Pronouncements" above.

Segment Information (Income Fro

Segment Information (Income From Continuing Operations, Before and After Federal Income Tax) (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017	[1]	Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net investment income	$ 54,109		$ 52,443		$ 45,553		$ 43,231		$ 42,587		$ 40,446		$ 41,430		$ 37,419		$ 195,336	$ 161,882	$ 130,754
Total net realized and unrealized (losses) gains	$ (37,935)	[2]	$ (4,787)	[2]	$ (1,652)	[2]	$ (10,549)	[2]	$ (1,128)	[2]	$ 6,798	[2]	$ 1,734	[2]	$ (1,045)	[2]	(54,923)	6,359	(4,937)
Total investment revenues																	140,413	168,241	125,817
Tax on investment income																	19,560	45,588	30,621
Total investment income, after federal income tax																	$ 120,853	$ 122,653	$ 95,196
Investments [Member]
Return on Equity																	6.90%	7.50%	6.50%
Standard Commercial Lines [Member]
Underwriting gain (loss), before federal income tax																	$ 109,104	$ 149,514	$ 146,435
Underwriting gain (loss), after federal income tax																	$ 86,192	$ 97,184	$ 95,183
Combined Ratio																	94.30%	91.60%	91.20%
Return on Equity																	4.90%	6.10%	6.40%
Standard Personal Lines [Member]
Underwriting gain (loss), before federal income tax																	$ 12,764	$ 11,104	$ 12,419
Underwriting gain (loss), after federal income tax																	$ 10,084	$ 7,217	$ 8,072
Combined Ratio																	95.80%	96.20%	95.60%
Return on Equity																	0.60%	0.40%	0.60%
Excess And Surplus Operations [Member]
Underwriting gain (loss), before federal income tax																	$ (695)	$ (6,282)	$ (6,921)
Underwriting gain (loss), after federal income tax																	$ (549)	$ (4,083)	$ (4,499)
Combined Ratio																	100.30%	103.00%	103.40%
Return on Equity																	0.00%	(0.30%)	(0.30%)
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.
[2]	Effective January 1, 2018, changes in unrealized gains and losses on our equity portfolio are recognized in income through "Net unrealized losses on equity securities" on our Consolidated Statements of Income, as a result of our adoption of ASU 2016-01. See Note 3. "Adoption of Accounting Pronouncements" above.

Segment Information (Reconcilia

Segment Information (Reconciliation of Segment Results to Income from Continuing Operations, before Federal Income Tax (Details)) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total investment revenues									$ 140,413	$ 168,241	$ 125,817
Interest expense									(24,419)	(24,354)	(22,771)
Corporate expenses									(25,446)	(36,255)	(35,024)
Income before federal income tax	$ 52,135	$ 67,130	$ 72,525	$ 19,931	$ 68,150	$ 67,315	$ 58,929	$ 67,574	211,721	261,968	219,955
Standard Commercial Lines [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting gain (loss), before federal income tax									109,104	149,514	146,435
Standard Personal Lines [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting gain (loss), before federal income tax									12,764	11,104	12,419
Excess And Surplus Operations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting gain (loss), before federal income tax									(695)	(6,282)	(6,921)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total all segments									$ 261,586	$ 322,577	$ 277,750

Earnings Per Share (Reconciliat

Earnings Per Share (Reconciliation of EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic EPS: [Abstract]
Net income	$ 45,760		$ 55,435	$ 58,819	$ 18,925	$ 30,242		$ 46,718	$ 41,426	$ 50,440	$ 178,939	$ 168,826	$ 158,495
Net income, basic shares											58,950	58,458	57,889
Basic net income per share	$ 0.77		$ 0.94	$ 1	$ 0.32	$ 0.52		$ 0.80	$ 0.71	$ 0.87	$ 3.04	$ 2.89	$ 2.74
Effect of dilutive securities: [Abstract]
Stock compensation plans, shares											763	899	858
Earnings Per Share, Diluted [Abstract]
Net income	$ 45,760		$ 55,435	$ 58,819	$ 18,925	$ 30,242		$ 46,718	$ 41,426	$ 50,440	$ 178,939	$ 168,826	$ 158,495
Shares net income, Diluted											59,713	59,357	58,747
Diluted net income per share	$ 0.76		$ 0.93	$ 0.99	$ 0.32	$ 0.51		$ 0.79	$ 0.70	$ 0.85	$ 3	$ 2.84	$ 2.70
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Federal Income Taxes (Reconcili

Federal Income Taxes (Reconciliation of Federal Income Tax on Income at the Corporate Rate to the Effective Tax Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%
Capital Loss Carrybacks	$ 3,800
Decrease in Discounted Loss Reserve	125,000	$ 35,000
Provisional Increase to Deferred Tax Asset	26,300	7,500
Provisional Increase to Deferred Tax Asset Per Year	3,300
Tax at statutory rate (21% in 2018 and 35% in 2017 and 2016)	44,461	91,689	$ 76,984
Tax-advantaged interest	(5,518)	(11,510)	(12,126)
Dividends received deduction	(647)	(1,961)	(1,114)
Federal Income Tax Expense Benefit Related to Executive Compensation	2,279	0	121
Share-based compensation expense income tax benefit	(3,093)	(4,281)	0
Tax Reform Deferred Tax Asset Impact	0	20,205	0
Other	(4,700)	(1,000)	(2,405)
Total federal income tax expense	$ 32,782	$ 93,142	$ 61,460

Federal Income Taxes (Deferred

Federal Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in Net Deferred Federal Income Tax Assets	$ 21,600
Net loss reserve discounting	43,285	$ 38,771
Net unearned premiums	53,556	50,267
Employee benefits	8,862	8,606
Long-term incentive compensation plans	9,095	12,221
Temporary investment write-downs	1,155	1,044
Net operating loss	0	54
Other	5,744	5,784
Total deferred tax assets	121,697	116,747
Deferred policy acquisition costs	53,049	47,484
Unrealized gains on investment securities	502	26,183
Other investment-related items, net	4,904	2,500
Accelerated depreciation and amortization	9,702	8,590
Total deferred tax liabilities	68,157	84,757
Deferred federal income tax	53,540	$ 31,990
Investments [Member]
Change in Net Deferred Federal Income Tax Assets	$ 18,600

Retirement Plans (Retirement Sa

Retirement Plans (Retirement Savings Plan) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Savings Plan [Member]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 15.8	$ 15.8	$ 15

Retirement Plans (Deferred Comp

Retirement Plans (Deferred Compensation Plan) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Compensation Plan Contributions By Employer	$ 0.4	$ 0.2	$ 0.3

Retirement Plans (Funded Status

Retirement Plans (Funded Status of Retirement Income Plan and Retirement Life Plan) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 400	$ 400	$ 500
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year	10,100
Benefit obligation, end of year	9,500	10,100
Retirement Income Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(8,358)	(4,928)	2,973
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year	364,411	330,588
Service cost	0	0	1,647
Interest cost	12,428	12,490	12,336
Actuarial losses (gains)	(31,738)	31,158
Benefits paid fair value	(10,422)	(9,825)
Benefit obligation, end of year	334,679	364,411	330,588
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets, beginning of year	363,673	316,515
Actual return on plan assets, net of expenses	(21,571)	46,983
Contributions by the employer to funded plans	0	10,000
Fair value of assets, end of year	331,680	363,673	316,515
Funded status	(2,999)	(738)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Liabilities	(2,999)	(738)
Net pension liability, end of year	(2,999)	(738)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net actuarial loss	98,057	87,438
Total	98,057	87,438
Weighted-Average Liability Asumptions
Accumulated benefit obligation	$ 334,679	$ 364,411
Discount rate	4.46%	3.78%
Retirement Life Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 300	$ 300	$ 300
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year	6,400
Benefit obligation, end of year	$ 5,800	$ 6,400

Retirement Plans (Components of

Retirement Plans (Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Compensation Plan Contributions By Employer	$ 400	$ 200	$ 300
Net actuarial loss (gain)	11,273	4,684	12,079
Reversal of amortization of net actuarial loss	(2,127)	(2,102)	(6,462)
Retirement Income Plan [Member]
Service cost	0	0	1,647
Interest cost	12,428	12,490	12,336
Expected return on plan assets	(22,767)	(19,419)	(17,309)
Amortization of unrecognized actuarial loss	1,981	2,001	6,299
Total net periodic cost	(8,358)	(4,928)	2,973
Net actuarial loss (gain)	12,600	3,594	11,316
Reversal of amortization of net actuarial loss	(1,981)	(2,001)	(6,299)
Total recognized in other comprehensive income	10,619	1,593	5,017
Total recognized in net periodic benefit cost and OCI	2,261	(3,335)	7,990
Estimated net actuarial loss that will be amortized from AOCI into net periodic benefit cost	2,600
Retirement Life Plan [Member]
Total net periodic cost	300	300	300
Supplemental Employee Retirement Plan [Member]
Total net periodic cost	$ 400	$ 400	$ 500

Retirement Plans (Weighted-Aver

Retirement Plans (Weighted-Average Expense Assumptions) (Details)		3 Months Ended	12 Months Ended
		Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Discount rate			4.12%
Expected return on plan assets			6.50%
Retirement Income Plan [Member]
Discount rate			3.78%	4.41%	4.69%
Expected return on plan assets			6.36%	6.24%	6.37%
Rate of compensation increase	[1]	4.00%	0.00%	0.00%	0.00%
[1]	This assumption was 4.00% through March 31, 2016, the date after which benefits ceased accruing for all participants of the Pension Plan.

Retirement Plans (Plan's Alloca

Retirement Plans (Plan's Allocated Target Ranges and Actual Weighted Average Asset Allocation by Investment Categories) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Plan Assets Redeployed into Risk Seeking Investments		$ 49
Actual percentage		100.00%	100.00%
Percent of Plan Assets Redeployed into Risk Seeking Investments		15.00%
Percent Hedge Against Projected Benefit Obligation		50.00%
Return Seeking Assets [Member]
Actual percentage		43.00%	58.00%
Liability Hedging Assets [Member]
Actual percentage		38.00%	40.00%
Short-term Investments Excluding Redeployment[Member]
Actual percentage	[1]	5.00%
Short-term Investments [Member]
Actual percentage	[1]	19.00%	2.00%
Minimum [Member] | Return Seeking Assets [Member]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description		0.15
Minimum [Member] | Liability Hedging Assets [Member]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description		0.35
Minimum [Member] | Short-term Investments [Member]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description		0
Maximum [Member] | Return Seeking Assets [Member]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description		0.7
Maximum [Member] | Liability Hedging Assets [Member]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description		0.75
Maximum [Member] | Short-term Investments [Member]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description		0.02
[1]	The actual percentage of assets allocated to short-term investments is higher than our target as of December 31, 2018 due to portfolio rebalancing initiatives that are expected to be completed during 2019. As part of this rebalancing initiative, $49 million, or 15%, of plan assets were redeployed into risk seeking assets in January 2019. Excluding the impact of this redeployment, our short-term investments represented 5% of plan assets at December 31, 2018.

Retirement Plans (Quantitative

Retirement Plans (Quantitative Disclosures of Retirement Income Plan's Invested Assets that are Measured at Fair Value on a Recurring Basis) (Details) - Retirement Income Plan [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Total Assets	$ 331,680	$ 363,673	$ 316,515
Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	331,834	363,075
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	300,725	327,427
Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,482	1,615
Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	980
Extended Duration Fixed Income [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		146,837
Extended Duration Fixed Income [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		146,837
Extended Duration Fixed Income [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		0
Extended Duration Fixed Income [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		0
Global Asset Allocation Fund [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		41,309
Global Asset Allocation Fund [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		41,309
Global Asset Allocation Fund [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		0
Global Asset Allocation Fund [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		0
International equity [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		67,989
International equity [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		67,989
International equity [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		0
International equity [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		0
US Global Equity [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		66,353
US Global Equity [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		66,353
US Global Equity [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		0
US Global Equity [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets		0
Global Equity [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	113,409	134,342
Global Equity [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	113,409	134,342
Global Equity [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Global Equity [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Real Assets [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	16,818	16,305
Real Assets [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Real Assets [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Real Assets [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Private Equity Funds [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	878	1,096
Private Equity Funds [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Private Equity Funds [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Private Equity Funds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Private Credit Funds [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	262	460
Private Credit Funds [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Private Credit Funds [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Private Credit Funds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Hedge Funds [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	7,889	15,192
Hedge Funds [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Hedge Funds [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Hedge Funds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	25,847	33,053
Alternative Investments [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Alternative Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Alternative Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Other Private Assets [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	3,780	980
Other Private Assets [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Other Private Assets [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Other Private Assets [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	980
Total Private Assets [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	29,627	34,033
Total Private Assets [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Total Private Assets [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Total Private Assets [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	980
Return Seeking Assets [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	143,036	209,684
Return Seeking Assets [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	113,409	175,651
Return Seeking Assets [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Return Seeking Assets [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	980
Fixed Income Securities [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	106,000
Fixed Income Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	106,000
Fixed Income Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0
Fixed Income Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0
US Treasury Securities [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	18,528
US Treasury Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	18,528
US Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0
US Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0
Short-term Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	62,788	4,939
Short-term Investments [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	62,788	4,939
Short-term Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Short-term Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Deposit Administration Contracts [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,482	1,615
Deposit Administration Contracts [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Deposit Administration Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,482	1,615
Deposit Administration Contracts [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Liability Hedging Assets [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	124,528	146,837
Liability Hedging Assets [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	124,528	146,837
Liability Hedging Assets [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Liability Hedging Assets [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	0
Cash And Short Term Investments [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	64,270	6,554
Cash And Short Term Investments [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	62,788	4,939
Cash And Short Term Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,482	1,615
Cash And Short Term Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value, recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	$ 0	$ 0

Retirement Plans (Benefit Payme

Retirement Plans (Benefit Payments) (Details) - Retirement Income Plan [Member] $ in Thousands	Dec. 31, 2018USD ($)
2,019	$ 13,920
2,020	13,869
2,021	15,026
2,022	16,159
2,023	17,134
2024 - 2028	$ 99,197

Share-Based Payments (Summary o

Share-Based Payments (Summary of Shares Available for Issuance) (Details)	Dec. 31, 2018shares
Omnibus Stock Plan 2014 [Member]
Schedule of Share-Based Compensation Shares Available for Issuance [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	4,750,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	3,461,192
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	864,478
Employee Stock [Member]
Schedule of Share-Based Compensation Shares Available for Issuance [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	1,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	429,181
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	0
Agent Stock Purchase Plan [Member]
Schedule of Share-Based Compensation Shares Available for Issuance [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	3,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	1,776,359
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	0

Shared-Based Payments (Summary

Shared-Based Payments (Summary of Retired Plans) (Details)	Dec. 31, 2018shares
Omnibus Stock Plan [Member]
Schedule of Share-Based Compensation Retired Plans [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	2,099,403
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	174,003
Stock Compensation Plan For Non Employee Directors [Member]
Schedule of Share-Based Compensation Retired Plans [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	65,770
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	65,770
Stock Option Share Based Compensation [Member] | Omnibus Stock Plan [Member]
Schedule of Share-Based Compensation Retired Plans [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	126,735
Restricted Stock Units (RSUs) [Member] | Omnibus Stock Plan [Member]
Schedule of Share-Based Compensation Retired Plans [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	47,268

Share-Based Payments (Summary_2

Share-Based Payments (Summary of the Restricted Stock Unit Transactions under Share-Based Payment Plans) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Incentive Plan [Member]
Weighted average remaining expense life	9 months
Share Based Compensation Liability Awards Amount Of Liability	$ 21.6	$ 37
Cash incentive unit payments made	$ 20.2	$ 14.2	$ 14.3
Restricted Stock Units (RSUs) [Member]
Unvested RSU awards at December 31, 2017	865,587
Granted in 2018, number of shares	303,550
Vested in 2018, number of shares	(303,606)
Forfeited in 2018, number of shares	(19,226)
Unvested RSU awards at December 31, 2018, number of shares	846,305	865,587
Unvested RSU awards at December 31, 2017, weighted average grant date fair value	$ 33.66
Granted in 2018, weighted average grant date fair value	55.96	$ 42.66	$ 32.53
Vested in 2018, weighted average grant date value	26.57
Forfeited in 2018, weighted average grant date fair value	42.62
Unvested RSU awards at December 31, 2018, weighted average grant date fair value	$ 44	$ 33.66
Total unrecognized compensation cost related to unvested RSU awards	$ 11
Weighted average remaining expense life	1 year 8 months
Total intrinsic value of shares vested	$ 18	$ 16	$ 12.6
Dividend Equivalent Units [Member]
Total intrinsic value of shares vested	$ 0.8	$ 0.9	$ 0.7

Share-Based Payments (Summary_3

Share-Based Payments (Summary of Stock Option Transactions under Share-Based Payment Plans) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Outstanding at December 31, 2017, number of shares	229,864
Granted in 2018, numbers of shares	0
Exercised in 2018, number of shares	(103,129)
Forfeited or expired 2018, number of shares	0
Outstanding at December 31, 2018, number of shares	126,735	229,864
Exercisable at December 31, 2018, number of shares	126,735
Outstanding at December 31, 2017, weighted average exercise price	$ 15.38
Granted in 2018, weighted average exercise price	0
Exercised in 2018, weighted average exercise price	16.62
Forfeited or expired 2018, weighted average exercise price	0
Outstanding at December 31, 2018, weighted average exercise price	14.37	$ 15.38
Exercisable as December 31, 2018, weighted average exercise price	$ 14.37
Outstanding at December 31, 2018, weighted average remaining contractual life in years	9 months 20 days
Exercisable at December 31, 2018, weighted average remaining contractual life in years	9 months 20 days
Outstanding at December 31, 2018, aggregate intrinsic value	$ 5,903
Exerciseable at December 31, 2018, aggregate intrinsic value	5,903
Total intrinsic value of options exercised	$ 4,500	$ 4,000	$ 2,300

Shared-Based Payments (Summar_2

Shared-Based Payments (Summary of ESPP and ASPP Shares Issued) (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Share-Based Compensation ESPP and ASPP Shares Granted [Line Items]
Stock Issued During Period Shares	540,337	635,521	720,323
Employee Stock [Member]
Schedule of Share-Based Compensation ESPP and ASPP Shares Granted [Line Items]
Stock Issued During Period Shares	70,448	75,093	88,432
Agent Stock Purchase Plan [Member]
Schedule of Share-Based Compensation ESPP and ASPP Shares Granted [Line Items]
Stock Issued During Period Shares	41,134	49,794	69,867

Share-Based Payments (Weighted

Share-Based Payments (Weighted Average Assumptions for Employee Stock Purchase Plan and Other Options) (Details) - Employee Stock Purchase Plan [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Risk-free interest rate	1.88%	1.07%	0.47%
Expected term	6 months	6 months	6 months
Dividend yield	1.30%	1.30%	1.70%
Expected volatility	18.00%	24.00%	31.00%

Share-Based Payments (Weighted-

Share-Based Payments (Weighted-Average Fair Value of Options and Stock Per Share) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock Units (RSUs) [Member]
Stock, weighted average grant date fair value	$ 55.96	$ 42.66	$ 32.53
Employee Stock Purchase Plan [Member]
Options, weighted average grant date fair value	2.67	2.73	2.63
15% of grant date market value	8.50	7.06	5.23
Total ESPP	11.17	9.79	7.86
Agent Stock Purchase Plan [Member]
Stock, weighted average grant date fair value	$ 5.99	$ 5.04	$ 3.79

Shared-Based Payments (Summar_3

Shared-Based Payments (Summary of Share-Based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Share-Based Compensation Expenses [Abstract]
Share-based compensation expense charged against net income, Before Tax	$ 19.3	$ 31.2	$ 30.3
Share-based compensation expense income tax benefit	(7)	(15)	(10.3)
Share-based Compensation Expense, Net of Tax	$ 12.3	$ 16.2	$ 20

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity ownership percentage of director of parent of general independent retail insurance agency	10.00%
Equity Ownership Percentage Of Son Of Director Of Parent	10.00%
Direct premiums written	$ 2,890,633	$ 2,733,459	$ 2,577,259
Due to Related Parties, Current	400	600
Contributions to the Selective Insurance Group Foundation	500	0	0
Costs and Expenses, Related Party	2,000	2,000	400
Due to Related Parties	1,000	500
Investments	5,960,651	5,685,179
Related Party Insurance Agency [Member]
Direct premiums written	10,100	11,100	10,400
Commissions paid to Rue Insurance	$ 2,100	2,300	2,100
Vanguard Group [Member]
Percentage Common Stock Owned by Related Party	10.10%
Related Party Transaction, Purchases from Related Party	$ 11,500
Investments	10,500	0	0
Investment Income, Net	$ (400)
BlackRock Inc [Member]
Percentage Common Stock Owned by Related Party	14.20%
Investments	$ 800	500	500
Sale of Related Party Investments			77,600
Related Party Transaction, Other Revenues from Transactions with Related Party			1,100
Investment Income, Net			(2,300)
Retirement Income Plan [Member] | Vanguard Group [Member]
Investments	0	86,300
Investment Income, Net	(5,500)	(9,100)	(5,400)
Retirement Income Plan [Member] | BlackRock Inc [Member]
Investments	131,900	134,300
Investment Income, Net	$ 9,300	$ (25,200)	$ (8,500)

Commitments and Contingencies_2

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Purchase amount of annuities	$ 21
Rental expense for operating leases for office space, equipment, and vehicles	$ 10.4	$ 10.8	$ 12.3
Capital Lease Agreements Expiration Period	2,022
Contractual Obligation Additional Investment in Alternative or Other Investments	$ 202.3
Common Stock [Member]
Contractual Obligation	17.8
Collateralized Loan Obligations [Member]
Contractual Obligation	$ 40.4

Commitments and Contingencies_3

Commitments and Contingencies (Future Minimum Rental Commitments) (Details) $ in Millions	Dec. 31, 2018USD ($)
2019- Capital Leases	$ 0.7
2020- Capital Leases	0.1
2021- Capital Leases	0
2022- Capital Leases	0
2023- Capital Leases	0
After 2023- Capital Leases	0
Total minimum payment required- Capital Leases	0.8
2019- Operating Leases	7.8
2020- Operating Leases	7.4
2021- Operating Leases	5.1
2022- Operating Leases	3.6
2023- Operating Leases	2.9
After 2023- Operating Leases	9.7
Total minimum payment required- Operating Leases	36.5
2019- Total Leases	8.5
2020- Total Leases	7.5
2021- Total Leases	5.1
2022- Total Leases	3.6
2023- Total Leases	2.9
After 2023- Total Leases	9.7
Total minimum payment required	$ 37.3

Statutory Financial Informati_3

Statutory Financial Information, Capital Requirements and Restrictions on Dividends and Transfers of Funds (Statutory Financial Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statutory unassigned surplus	$ 1,232.8	$ 1,137.3
Statutory surplus	1,768.4	1,672.9
Statutory net income	210.6	221.2	$ 202.3
Selective Insurace Company of America (SICA) [Member]
Statutory unassigned surplus	478.6	455.5
Statutory surplus	632.8	609.7
Statutory net income	78	84.6	72.2
Selective Way Insurance Company (SWIC) [Member]
Statutory unassigned surplus	300.2	276.1
Statutory surplus	349.3	325.1
Statutory net income	47.5	43.6	41.2
Selective Insurance Company of South Carolina (SICSC) [Member]
Statutory unassigned surplus	119.4	112.9
Statutory surplus	150.7	144.1
Statutory net income	16.5	17.9	17.4
Selective Insurance Company of the Southeast (SICSE) [Member]
Statutory unassigned surplus	92.2	86.2
Statutory surplus	117.7	111.8
Statutory net income	12.9	14.7	13.4
Selective Insurance Company of New York (SICNY) [Member]
Statutory unassigned surplus	86.5	78.8
Statutory surplus	114.2	106.5
Statutory net income	12	13.4	12.9
Selective Insurance Company of New England (SICNE) [Member]
Statutory unassigned surplus	19.9	16.1
Statutory surplus	50	46.3
Statutory net income	5.6	6.3	5.9
Selective Auto Insurance Company of New Jersey (SAICNJ) [Member]
Statutory unassigned surplus	50.3	42.1
Statutory surplus	93.2	84.9
Statutory net income	9.9	11.4	11.5
Mesa Underwriting Specialty Insurance Company (MUSIC) [Member]
Statutory unassigned surplus	23	21.4
Statutory surplus	91.5	89.9
Statutory net income	9.4	10.3	9.7
Selective Casualty Insurance Company (SCIC) [Member]
Statutory unassigned surplus	44.9	34.5
Statutory surplus	119.3	109
Statutory net income	13.3	13.4	12.6
Selective Fire and Casualty Insurance Company (SFCIC) [Member]
Statutory unassigned surplus	17.8	13.7
Statutory surplus	49.7	45.6
Statutory net income	$ 5.5	$ 5.6	$ 5.5

Statutory Financial Informati_4

Statutory Financial Information, Capital Requirements, and Restrictions on Dividends and Transfers of Funds (Dividends) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total stockholders’ equity	$ 1,791,802	$ 1,712,957	$ 1,531,370
Ordinary dividends paid	100,100
Maximum ordinary dividends to be paid in the next fiscal year	$ 210,000
Maximum borrowing percentage	10.00%
New Jersey Dividend Restriction	10.00%
New York Dividend Restriction on Insurer's Statutory Surplus	10.00%
New York Dividend Restriction on Adjusted Net Investment Income	100.00%
Selective Insurace Company of America (SICA) [Member]
Ordinary dividends paid	$ 43,000
Maximum ordinary dividends to be paid in the next fiscal year	78,000
Selective Way Insurance Company (SWIC) [Member]
Ordinary dividends paid	19,000
Maximum ordinary dividends to be paid in the next fiscal year	47,500
Selective Insurance Company of South Carolina (SICSC) [Member]
Ordinary dividends paid	10,000
Maximum ordinary dividends to be paid in the next fiscal year	16,500
Selective Insurance Company of the Southeast (SICSE) [Member]
Ordinary dividends paid	7,500
Maximum ordinary dividends to be paid in the next fiscal year	12,900
Selective Insurance Company of New York (SICNY) [Member]
Ordinary dividends paid	4,500
Maximum ordinary dividends to be paid in the next fiscal year	11,400
Selective Insurance Company of New England (SICNE) [Member]
Ordinary dividends paid	2,000
Maximum ordinary dividends to be paid in the next fiscal year	5,600
Selective Auto Insurance Company of New Jersey (SAICNJ) [Member]
Ordinary dividends paid	2,500
Maximum ordinary dividends to be paid in the next fiscal year	9,900
Mesa Underwriting Specialty Insurance Company (MUSIC) [Member]
Ordinary dividends paid	7,100
Maximum ordinary dividends to be paid in the next fiscal year	9,400
Selective Casualty Insurance Company (SCIC) [Member]
Ordinary dividends paid	3,000
Maximum ordinary dividends to be paid in the next fiscal year	13,300
Selective Fire and Casualty Insurance Company (SFCIC) [Member]
Ordinary dividends paid	1,500
Maximum ordinary dividends to be paid in the next fiscal year	5,500
Parent Company [Member]
Total stockholders’ equity	1,900,000
Maximum ordinary dividends to be paid in the next fiscal year	146,000
Additional Borrowing Capacity for Parent	$ 70,500

Quarterly Financial Informati_3

Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax Reform Deferred Tax Asset Impact																	$ 0	$ 20,205	$ 0
Net premiums earned	$ 625,288	[1]	$ 614,277		$ 604,836		$ 591,828		$ 590,088	[1]	$ 572,055		$ 568,030		$ 560,854		2,436,229	2,291,027	2,149,572
Net investment income earned	54,109	[1]	52,443		45,553		43,231		42,587	[1]	40,446		41,430		37,419		195,336	161,882	130,754
Net realized and unrealized (losses) gains2	(37,935)	[1],[2]	(4,787)	[2]	(1,652)	[2]	(10,549)	[2]	(1,128)	[1],[2]	6,798	[2]	1,734	[2]	(1,045)	[2]	(54,923)	6,359	(4,937)
Other income	1,542	[1]	2,538		3,179		2,179		2,190	[1]	1,994		3,291		3,241		9,438	10,716	8,881
Total revenues	643,004	[1]	664,471		651,916		626,689		633,737	[1]	621,293		614,485		600,469		2,586,080	2,469,984	2,284,270
Income before federal income tax	52,135		67,130		72,525		19,931		68,150		67,315		58,929		67,574		211,721	261,968	219,955
Net income	$ 45,760	[1]	$ 55,435		$ 58,819		$ 18,925		$ 30,242	[1]	$ 46,718		$ 41,426		$ 50,440		$ 178,939	$ 168,826	$ 158,495
Basic net income per share	$ 0.77	[1]	$ 0.94		$ 1		$ 0.32		$ 0.52	[1]	$ 0.80		$ 0.71		$ 0.87		$ 3.04	$ 2.89	$ 2.74
Diluted net income per share	$ 0.76	[1]	$ 0.93		$ 0.99		$ 0.32		$ 0.51	[1]	$ 0.79		$ 0.70		$ 0.85		$ 3	$ 2.84	$ 2.70
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.
[2]	Effective January 1, 2018, changes in unrealized gains and losses on our equity portfolio are recognized in income through "Net unrealized losses on equity securities" on our Consolidated Statements of Income, as a result of our adoption of ASU 2016-01. See Note 3. "Adoption of Accounting Pronouncements" above.

Schedule I - Summary of Inves_2

Schedule I - Summary of Investments - Other Than Investments in Related Parties (Details) $ in Thousands	Dec. 31, 2018USD ($)
Amortized Cost or Cost	$ 5,948,735
Carrying Amount	5,960,651
Short-term Investments [Member]
Amortized Cost or Cost	323,864
Fair Value	323,864
Carrying Amount	323,864
Other Investments [Member]
Amortized Cost or Cost	178,938
Carrying Amount	178,938
Held-to-maturity Securities [Member] | Obligations of States and Political Subdivisions [Member]
Amortized Cost or Cost	17,431
Fair Value	17,969
Carrying Amount	17,470
Held-to-maturity Securities [Member] | Public Utilities
Amortized Cost or Cost	4,707
Fair Value	5,264
Carrying Amount	4,818
Held-to-maturity Securities [Member] | All other corporate securities
Amortized Cost or Cost	14,883
Fair Value	15,084
Carrying Amount	14,822
Held-to-maturity Securities [Member] | Fixed Income Securities [Member]
Amortized Cost or Cost	37,021
Fair Value	38,317
Carrying Amount	37,110
AFS Fixed Income Securities [Member] | US Government Agencies Debt Securities [Member]
Amortized Cost or Cost	120,092
Fair Value	121,310
Carrying Amount	121,310
AFS Fixed Income Securities [Member] | Foreign Government
Amortized Cost or Cost	23,202
Fair Value	23,131
Carrying Amount	23,131
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
Amortized Cost or Cost	1,121,615
Fair Value	1,138,469
Carrying Amount	1,138,469
AFS Fixed Income Securities [Member] | Public Utilities
Amortized Cost or Cost	28,464
Fair Value	28,393
Carrying Amount	28,393
AFS Fixed Income Securities [Member] | All other corporate securities
Amortized Cost or Cost	1,611,388
Fair Value	1,589,015
Carrying Amount	1,589,015
AFS Fixed Income Securities [Member] | CLO and Other ABS
Amortized Cost or Cost	720,193
Fair Value	717,362
Carrying Amount	717,362
AFS Fixed Income Securities [Member] | Commercial Mortgage-backed Securities (CMBS) [Member]
Amortized Cost or Cost	527,409
Fair Value	527,078
Carrying Amount	527,078
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
Amortized Cost or Cost	1,118,435
Fair Value	1,128,342
Carrying Amount	1,128,342
AFS Fixed Income Securities [Member] | Fixed Income Securities [Member]
Amortized Cost or Cost	5,270,798
Fair Value	5,273,100
Carrying Amount	5,273,100
Equity Securities [Member] | Public Utilities
Amortized Cost or Cost	2,416
Fair Value	2,732
Carrying Amount	2,732
Equity Securities [Member] | Banks, trusts, and insurance companies
Amortized Cost or Cost	7,448
Fair Value	8,331
Carrying Amount	8,331
Equity Securities [Member] | Industrial, miscellaneous and all other
Amortized Cost or Cost	125,361
Fair Value	133,664
Carrying Amount	133,664
Equity Securities [Member] | Preferred Stock [Member]
Amortized Cost or Cost	2,889
Fair Value	2,912
Carrying Amount	2,912
Equity Securities [Member] | Equity Securities [Member]
Amortized Cost or Cost	138,114
Fair Value	147,639
Carrying Amount	$ 147,639

Parent Corporation Balance Shee

Parent Corporation Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Fixed income securities, available-for-sale – at fair value (amortized cost: $111,208 – 2018; $89,799 – 2017)	$ 5,273,100	$ 5,162,522
Short-term investments	323,864	165,555
Cash	505	534
Current federal income tax	0	3,243
Deferred federal income tax	53,540	31,990
Other assets	76,877	78,195
Total assets	7,952,729	7,686,431
Liabilities:
Long-term debt	439,540	439,116
Other liabilities	277,579	281,624
Total liabilities	6,160,927	5,973,474
Stockholders’ Equity:
Preferred stock of $0 par value per share: Authorized shares: 5,000,000; no shares issued or outstanding	0	0
Common stock of $2 par value per share Authorized shares: 360,000,000 Issued: 102,848,394 - 2018; 102,284,564 - 2017	205,697	204,569
Additional paid-in capital	390,315	367,717
Retained earnings	1,858,414	1,698,613
Accumulated other comprehensive (loss) income	(77,956)	20,170
Treasury stock – at cost (shares: 43,899,840 – 2018; 43,789,442 – 2017)	(584,668)	(578,112)
Total stockholders’ equity	1,791,802	1,712,957	$ 1,531,370
Total liabilities and stockholders’ equity	7,952,729	7,686,431
Parent Company [Member]
ASSETS
Fixed income securities, available-for-sale – at fair value (amortized cost: $111,208 – 2018; $89,799 – 2017)	110,098	89,872
Short-term investments	35,358	24,080
Cash	505	534	$ 458	$ 898
Investment in subsidiaries	2,057,218	2,013,304
Current federal income tax	14,161	22,266
Deferred federal income tax	10,346	13,239
Other assets	1,186	871
Total assets	2,228,872	2,164,166
Liabilities:
Long-term debt	329,540	329,116
Intercompany notes payable	77,517	78,443
Accrued long-term stock compensation	21,574	37,017
Other liabilities	8,439	6,633
Total liabilities	437,070	451,209
Stockholders’ Equity:
Preferred stock of $0 par value per share: Authorized shares: 5,000,000; no shares issued or outstanding	0	0
Common stock of $2 par value per share Authorized shares: 360,000,000 Issued: 102,848,394 - 2018; 102,284,564 - 2017	205,697	204,569
Additional paid-in capital	390,315	367,717
Retained earnings	1,858,414	1,698,613
Accumulated other comprehensive (loss) income	(77,956)	20,170
Treasury stock – at cost (shares: 43,899,840 – 2018; 43,789,442 – 2017)	(584,668)	(578,112)
Total stockholders’ equity	1,791,802	1,712,957
Total liabilities and stockholders’ equity	$ 2,228,872	$ 2,164,166

Parent Corporation Balance Sh_2

Parent Corporation Balance Sheets (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fixed income securities, available-for-sale, amortized cost	$ 5,270,798	$ 5,076,716
Preferred stock, par value per share	$ 0	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued	0	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 2	$ 2
Common stock, shares authorized	360,000,000	360,000,000
Common stock, shares issued	102,848,394	102,284,564
Treasury stock, shares	43,899,840	43,789,442
Parent Company [Member]
Fixed income securities, available-for-sale, amortized cost	$ 111,208	$ 89,799
Preferred stock, par value per share	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 2	$ 2
Common stock, shares authorized	360,000,000	360,000,000
Common stock, shares issued	102,848,394	102,284,564
Treasury stock, shares	43,899,840	43,789,442

Parent Corporation Statements o

Parent Corporation Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Dividends from subsidaries											$ (100,100)
Net investment income earned	$ 54,109		$ 52,443	$ 45,553	$ 43,231	$ 42,587		$ 40,446	$ 41,430	$ 37,419	195,336	$ 161,882	$ 130,754
Net realized losses											(25,554)	6,359	(4,937)
Total revenues	643,004		664,471	651,916	626,689	633,737		621,293	614,485	600,469	2,586,080	2,469,984	2,284,270
Expenses:
Interest expense											24,419	24,354	22,771
Total expenses											2,374,359	2,208,016	2,064,315
Federal income tax (benefit) expense:
Current											35,012	62,184	48,581
Deferred											(2,230)	30,958	12,879
Total federal income tax expense											32,782	93,142	61,460
Net income	$ 45,760		$ 55,435	$ 58,819	$ 18,925	$ 30,242		$ 46,718	$ 41,426	$ 50,440	178,939	168,826	158,495
Parent Company [Member]
Revenues:
Dividends from subsidaries											100,060	80,096	61,014
Net investment income earned											3,425	2,044	1,259
Net realized losses											(1,567)	(15)	(220)
Total revenues											101,918	82,125	62,053
Expenses:
Interest expense											24,652	24,721	24,030
Other expenses											25,446	36,251	35,020
Total expenses											50,098	60,972	59,050
Income before federal income tax											51,820	21,153	3,003
Federal income tax (benefit) expense:
Current											(14,173)	(22,187)	(17,924)
Deferred											3,141	6,311	(2,143)
Total federal income tax expense											(11,032)	(15,876)	(20,067)
Net income before equity in undistributed income of subsidiaries											62,852	37,029	23,070
Equity In Undistributed Income Of Continuing Subsidiaries, Net Of Tax											116,087	131,797	135,425
Net income											$ 178,939	$ 168,826	$ 158,495
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Parent Corporation Statements_2

Parent Corporation Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net income	$ 45,760	[1]	$ 55,435	$ 58,819	$ 18,925	$ 30,242	[1]	$ 46,718	$ 41,426	$ 50,440	$ 178,939	$ 168,826	$ 158,495
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense											14,507	12,089	10,449
Net realized losses											25,554	(6,359)	4,937
Amortization - other											44,874	52,100	61,671
Changes in assets and liabilities:
Decrease (increase) in net federal income taxes											2,428	30,918	11,150
Increase in other assets											372	2,643	4,979
Increase in other liabilities											(13,343)	27,297	9,191
Net cash provided by operating activities											454,944	379,545	329,509
Investing Activities
Purchase of fixed income securities, available-for-sale											(2,918,203)	(2,130,362)	(1,982,023)
Redemption and maturities of fixed income securities, available-for-sale											638,916	555,216	641,524
Sale of fixed income securities, available for sale											12,106	58,832	102,868
Purchase of short-term investments											(4,259,734)	(4,280,553)	(3,499,380)
Sale of short-term investments											4,101,530	4,338,318	3,470,022
Net cash used in investing activities											(435,688)	(332,658)	(320,736)
Financing Activities
Dividends to stockholders											(42,097)	(37,045)	(33,758)
Acquisition of treasury stock											(6,556)	(6,015)	(4,992)
Net proceeds from stock purchase and compensation plans											7,252	7,599	7,811
Excess tax benefits from share-based payment arrangements											0	0	1,819
Net cash used in financing activities											(47,047)	(39,582)	15,878
Cash, beginning of year					534						534
Cash, end of year	505					534					505	534
Parent Company [Member]
Operating Activities
Net income											178,939	168,826	158,495
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income of subsidiaries, net of tax											(116,087)	(131,797)	(135,425)
Stock-based compensation expense											14,507	12,089	10,449
Net realized losses											1,567	15	220
Amortization - other											567	678	648
Changes in assets and liabilities:
(Decrease) increase in accrued long-term stock compensation											(15,443)	4,988	5,564
Decrease (increase) in net federal income taxes											11,246	3,811	(3,612)
Increase in other assets											(343)	(60)	(202)
Increase in other liabilities											1,712	714	80
Net cash provided by operating activities											76,665	59,264	36,217
Investing Activities
Purchase of fixed income securities, available-for-sale											(75,046)	(58,832)	(45,789)
Redemption and maturities of fixed income securities, available-for-sale											6,849	10,465	14,983
Sale of fixed income securities, available for sale											45,099	31,819	18,768
Purchase of short-term investments											(207,115)	(185,590)	(119,501)
Sale of short-term investments											195,846	179,292	130,841
Net cash used in investing activities											(34,367)	(22,846)	(698)
Financing Activities
Dividends to stockholders											(42,097)	(37,045)	(33,758)
Acquisition of treasury stock											(6,556)	(6,015)	(4,992)
Net proceeds from stock purchase and compensation plans											7,252	7,599	7,811
Excess tax benefits from share-based payment arrangements											0	0	1,819
Principal payments of borrowings from subsidiaries											(926)	(881)	(6,839)
Net cash used in financing activities											(42,327)	(36,342)	(35,959)
Net (decrease) increase in cash											(29)	76	(440)
Cash, beginning of year					$ 534					$ 458	534	458	898
Cash, end of year	$ 505					$ 534					$ 505	$ 534	$ 458
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Schedule III - Supplementary _2

Schedule III - Supplementary Insurance Information (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred policy acquisition costs	$ 252,612					$ 235,055					$ 252,612	$ 235,055	$ 222,564
Reserve for loss and loss expenses	3,893,868					3,771,240					3,893,868	3,771,240	3,691,719
Unearned premiums	1,431,932					1,349,644					1,431,932	1,349,644	1,262,819
Net premiums earned											2,436,229	2,291,027	2,149,572
Net investment income											140,413	168,241	125,817
Loss and loss expense incurred											1,498,134	1,345,074	1,234,797
Amortization of deferred policy acquisition costs											495,042	469,236	450,328
Other operating expenses											321,880	322,381	312,514
Net premiums written											2,514,286	2,370,641	2,237,288
Other insurance expenses											331,318	333,097	321,395
Other income	(1,542)	[1]	$ (2,538)	$ (3,179)	$ (2,179)	(2,190)	[1]	$ (1,994)	$ (3,291)	$ (3,241)	(9,438)	(10,716)	(8,881)
Standard Commercial Lines [Member]
Deferred policy acquisition costs	206,391					193,408					206,391	193,408	181,193
Reserve for loss and loss expenses	3,283,531					3,165,217					3,283,531	3,165,217	3,098,554
Unearned premiums	1,020,054					956,173					1,020,054	956,173	884,976
Net premiums earned											1,912,222	1,788,499	1,665,483
Net investment income											0	0	0
Loss and loss expense incurred											1,141,038	1,008,150	913,506
Amortization of deferred policy acquisition costs											412,420	387,552	367,813
Other operating expenses											249,660	243,283	237,729
Net premiums written											1,975,683	1,858,735	1,745,782
Standard Personal Lines [Member]
Deferred policy acquisition costs	18,070					16,952					18,070	16,952	16,664
Reserve for loss and loss expenses	223,223					263,166					223,223	263,166	286,081
Unearned premiums	304,085					295,435					304,085	295,435	282,111
Net premiums earned											304,441	289,701	280,607
Net investment income											0	0	0
Loss and loss expense incurred											206,752	189,294	177,749
Amortization of deferred policy acquisition costs											33,617	32,542	34,105
Other operating expenses											51,308	56,761	56,334
Net premiums written											309,277	296,775	281,822
Excess And Surplus Operations [Member]
Deferred policy acquisition costs	28,151					24,695					28,151	24,695	24,707
Reserve for loss and loss expenses	387,114					342,857					387,114	342,857	307,084
Unearned premiums	107,793					98,036					107,793	98,036	95,732
Net premiums earned											219,566	212,827	203,482
Net investment income											0	0	0
Loss and loss expense incurred											150,344	147,630	143,542
Amortization of deferred policy acquisition costs											49,005	49,142	48,410
Other operating expenses											20,912	22,337	18,451
Net premiums written											229,326	215,131	209,684
Investments Segment [Member]
Deferred policy acquisition costs	0					0					0	0	0
Reserve for loss and loss expenses	0					0					0	0	0
Unearned premiums	$ 0					$ 0					0	0	0
Net premiums earned											0	0	0
Net investment income											140,413	168,241	125,817
Loss and loss expense incurred											0	0	0
Amortization of deferred policy acquisition costs											0	0	0
Other operating expenses											0	0	0
Net premiums written											0	0	0
Miscellaneous Income [Member]
Other income											$ (9,438)	$ (10,716)	$ (8,881)
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Schedule IV - Reinsurance (Deta

Schedule IV - Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Direct Amount											$ 2,808,764	$ 2,647,488	$ 2,484,715
Assumed From Other Companies											25,831	25,831	28,214
Ceded to Other Companies											398,366	382,292	363,357
Total Net Premiums Earned	$ 625,288		$ 614,277	$ 604,836	$ 591,828	$ 590,088		$ 572,055	$ 568,030	$ 560,854	$ 2,436,229	$ 2,291,027	$ 2,149,572
Percentage of Amount Assumed to Net											1.00%	1.00%	1.00%
Accident and Health Insurance Segment [Member]
Direct Amount											$ 19	$ 24	$ 32
Assumed From Other Companies											0	0	0
Ceded to Other Companies											19	24	0
Total Net Premiums Earned											$ 0	$ 0	$ 32
Percentage of Amount Assumed to Net											0.00%	0.00%	0.00%
Property and liability insurance [Member]
Direct Amount											$ 2,808,745	$ 2,647,464	$ 2,484,683
Assumed From Other Companies											25,831	25,831	28,214
Ceded to Other Companies											398,347	382,268	363,357
Total Net Premiums Earned											$ 2,436,229	$ 2,291,027	$ 2,149,540
Percentage of Amount Assumed to Net											1.00%	1.00%	1.00%
[1]	Results for the fourth quarter of 2017 include the impact of the $20.2 million write off of deferred tax assets required with the implementation of Tax Reform. See Note 13. "Federal Income Taxes" above for additional information.

Schedule V - Allowance for Unc

Schedule V - Allowance for Uncollectible Premiums and Other Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance, January 1	$ 14,600	$ 11,480	$ 10,122
Additions	4,022	6,414	4,669
Deductions	(4,722)	(3,294)	(3,311)
Balance, December 31	$ 13,900	$ 14,600	$ 11,480