Selective Insurance (SIGI) 10-Q 26 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 15, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Registrant Name	SELECTIVE INSURANCE GROUP INC
Entity Central Index Key	230,557
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock , Shares Outstanding		58,888,985
Entity Emerging Growth Company	false
Entity Small Business	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
ASSETS
Fixed income securities, held-to-maturity – at carrying value (fair value: $46,240 – 2018; $44,100 – 2017)	$ 44,582	$ 42,129
Fixed income securities, available-for-sale – at fair value (amortized cost: $5,216,964 – 2018; $5,076,716 – 2017)	5,190,156	5,162,522
Equity securities – at fair value (cost: $134,530 – 2018)	157,867
Equity securities, available-for-sale – at fair value (cost: $143,811 – 2017)		182,705
Short-term investments (at cost which approximates fair value)	304,572	165,555
Other investments	163,930	132,268
Total investments (Note 4 and 6)	5,861,107	5,685,179
Cash	446	534
Restricted cash	12,386	44,176
Interest and dividends due or accrued	41,016	40,897
Premiums receivable, net of allowance for uncollectible accounts of: $10,100 – 2018; $10,000 – 2017	826,923	747,029
Reinsurance recoverable, net of allowance for uncollectible accounts of: $4,500 – 2018; $4,600 – 2017	603,827	594,832
Prepaid reinsurance premiums	167,108	153,493
Current federal income tax	0	3,243
Deferred federal income tax	52,347	31,990
Property and equipment – at cost, net of accumulated depreciation and amortization of: $227,639 – 2018; $213,227 – 2017	64,225	63,959
Deferred policy acquisition costs	258,033	235,055
Goodwill	7,849	7,849
Other assets	91,485	78,195
Total assets	7,986,752	7,686,431
Liabilities And Stockholders' Equity
Reserve for loss and loss expense (Note 8)	3,925,155	3,771,240
Unearned premiums	1,483,794	1,349,644
Long-term debt	439,436	439,116
Current federal income tax	12,133	0
Accrued salaries and benefits	95,352	131,850
Other liabilities	292,362	281,624
Total liabilities	6,248,232	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: 102,786,738 – 2018; 102,284,564 – 2017	205,573	204,569
Additional paid-in capital	385,451	367,717
Retained earnings	1,824,607	1,698,613
Accumulated other comprehensive (loss) income (Note 11)	(92,576)	20,170
Treasury stock – at cost (shares: 43,897,753 – 2018; 43,789,442 – 2017)	(584,535)	(578,112)
Total stockholders' equity	1,738,520	1,712,957
Commitments and contingencies
Total liabilities and stockholders' equity	$ 7,986,752	$ 7,686,431

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fixed income securities, held-to-maturity, fair value	$ 46,240	$ 44,100
Fixed income securities, available-for-sale, amortized cost	5,216,964	5,076,716
Equity securities, cost	134,530
Equity securities, available-for-sale, cost		143,811
Premiums receivable, allowance for uncollectible accounts	10,100	10,000
Reinsurance recoverable, allowance for uncollectible accounts	4,500	4,600
Property and equipment - at cost, accumulated depreciation and amortization	$ 227,639	$ 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	102,786,738	102,284,564
Treasury stock - at cost, shares	43,897,753	43,789,442

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Net premiums earned	$ 614,277	$ 572,055	$ 1,810,941	$ 1,700,939
Net investment income earned	52,443	40,446	141,227	119,295
Net realized and unrealized (losses) gains:
Net realized investment (losses) gains on disposals	(751)	6,871	4,034	12,252
Other-than-temporary impairments	(1,426)	(43)	(5,459)	(4,729)
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	(30)	0	(36)
Unrealized losses on equity securities	(2,610)	0	(15,563)	0
Total net realized and unrealized (losses) gains	(4,787)	6,798	(16,988)	7,487
Other income	2,538	1,994	7,896	8,526
Total revenues	664,471	621,293	1,943,076	1,836,247
Expenses:
Loss and loss expense incurred	379,199	344,587	1,130,468	1,003,618
Amortization of deferred policy acquisition costs	124,511	118,143	368,265	350,071
Other insurance expenses	80,108	78,874	244,342	243,799
Interest expense	6,073	6,085	18,350	18,272
Corporate expenses	7,450	6,289	22,065	26,669
Total expenses	597,341	553,978	1,783,490	1,642,429
Income before federal income tax	67,130	67,315	159,586	193,818
Federal income tax expense:
Current	10,314	16,859	23,529	48,917
Deferred	1,381	3,738	2,878	6,317
Total federal income tax expense	11,695	20,597	26,407	55,234
Net income	$ 55,435	$ 46,718	$ 133,179	$ 138,584
Earnings per share:
Basic net income	$ 0.94	$ 0.80	$ 2.26	$ 2.37
Diluted net income	0.93	0.79	2.23	2.34
Dividends to stockholders	$ 0.18	$ 0.16	$ 0.54	$ 0.48

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income	$ 55,435	$ 46,718	$ 133,179	$ 138,584
Unrealized holding (losses) gains arising during period	(17,036)	10,874	(103,389)	50,961
Non-credit portion of other-than-temporary impairments recognized in other comprehensive income	0	19	0	23
Amounts reclassified into net income: Held-to-maturity securities	(6)	(35)	(22)	(95)
Amounts reclassified into net income: Non-credit other than temporary impairments	0	25	0	25
Amounts reclassified into net income: Realized losses (gains) on disposals of available-for-sale securities	8,563	(4,394)	14,424	(4,638)
Total unrealized (losses) gains on investment securities	(8,479)	6,489	(88,987)	46,276
Amount reclassified into net income: Net actuarial loss	420	329	1,260	989
Total defined benefit pension and post-retirement plans	420	329	1,260	989
Other comprehensive (loss) income	(8,059)	6,818	(87,727)	47,265
Comprehensive income	$ 47,376	$ 53,536	$ 45,452	$ 185,849

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 income (loss) [Member]	Treasury stock [Member]
Balance at beginning of year, as adjusted				$ 1,568,881	$ (15,950)
Beginning of year at Dec. 31, 2016		$ 203,241	$ 347,295	1,568,881	(15,950)	$ (572,097)
Dividend reinvestment plan (shares: 17,683 – 2018; 22,278 – 2017)		45	1,025
Stock purchase and compensation plans (shares: 484,491 – 2018; 537,588 – 2017)		1,075	14,417
Net income	$ 138,584			138,584
Dividends to stockholders ($0.54 per share – 2018; $0.48 per share – 2017)				(28,424)
Other comprehensive (loss) income	47,265				47,265
Acquisition of treasury stock (shares: 108,311 – 2018; 136,012 – 2017)						(6,005)
End of period at Sep. 30, 2017	1,699,352	204,361	362,737	1,679,041	31,315	(578,102)
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01 [Member]				0	0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2018-02 [Member]				0	0
Balance at beginning of year, as adjusted				1,723,632	(4,849)
Beginning of year at Dec. 31, 2017	1,712,957	204,569	367,717	1,698,613	20,170	(578,112)
Dividend reinvestment plan (shares: 17,683 – 2018; 22,278 – 2017)		35	1,013
Stock purchase and compensation plans (shares: 484,491 – 2018; 537,588 – 2017)		969	16,721
Net income	133,179			133,179
Dividends to stockholders ($0.54 per share – 2018; $0.48 per share – 2017)				(32,204)
Other comprehensive (loss) income	(87,727)				(87,727)
Acquisition of treasury stock (shares: 108,311 – 2018; 136,012 – 2017)						(6,423)
End of period at Sep. 30, 2018	$ 1,738,520	$ 205,573	$ 385,451	1,824,607	(92,576)	$ (584,535)
Cumulative effect of new accounting principle in period of adoption					(25,019)
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01 [Member]				30,726	(30,726)
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2018-02 [Member]				$ (5,707)	$ 5,707

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Dividend reinvestment plan, shares			17,683	22,278
Stock purchase and compensation plans, shares			484,491	537,588
Dividends to stockholders, per share	$ 0.18	$ 0.16	$ 0.54	$ 0.48
Acquisition of treasury stock, shares			108,311	136,012
Preferred stock, par value per share	$ 0	$ 0	$ 0	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued	0	0	0	0	0
Series A Preferred Stock [Member]
Preferred stock, par value per share	$ 0	$ 0	$ 0	$ 0
Preferred stock, shares authorized	300,000	300,000	300,000	300,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flow - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating Activities
Net income	$ 133,179	$ 138,584
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	34,961	38,163
Stock-based compensation expense	12,150	10,139
Undistributed gains of equity method investments	(4,243)	(4,247)
Distributions in excess of current year income of equity method investments	3,210	552
Loss on disposal of fixed assets	62	998
Net realized and unrealized losses (gains)	16,988	(7,487)
Changes in assets and liabilities:
Increase in reserve for loss and loss expense, net of reinsurance recoverable	144,920	104,429
Increase in unearned premiums, net of prepaid reinsurance	120,535	115,855
Decrease in net federal income taxes	18,339	15,674
Increase in premiums receivable	(79,894)	(88,175)
Increase in deferred policy acquisition costs	(22,978)	(19,592)
Decrease (increase) in interest and dividends due or accrued	72	(1,088)
Decrease in accrued salaries and benefits	(36,498)	(19,804)
Increase in other assets	(13,881)	(6,304)
(Decrease) increase in other liabilities	(34,437)	12,621
Net cash provided by operating activities	292,485	290,318
Investing Activities
Purchase of fixed income securities, held-to-maturity	(7,150)	0
Purchase of fixed income securities, available-for-sale	(1,974,253)	(1,517,474)
Purchase of equity securities	(57,834)
Purchase of equity securities, available-for-sale		(44,480)
Purchase of other investments	(47,238)	(34,586)
Purchase of short-term investments	(2,711,360)	(3,025,824)
Sale of fixed income securities, available-for-sale	1,382,677	811,991
Sale of short-term investments	2,572,399	3,032,802
Redemption and maturities of fixed income securities, held-to-maturity	3,923	36,092
Redemption and maturities of fixed income securities, available-for-sale	456,037	439,616
Sale of equity securities	79,676
Sale of equity securities, available-for-sale		19,007
Sale of other investments	3,497	0
Distributions from other investments	23,420	17,041
Purchase of property and equipment	(11,150)	(11,806)
Net cash used in investing activities	(287,356)	(277,621)
Financing Activities
Dividends to stockholders	(30,694)	(26,915)
Acquisition of treasury stock	(6,423)	(6,005)
Net proceeds from stock purchase and compensation plans	5,001	4,744
Proceeds from borrowings	130,000	64,000
Repayments of borrowings	(130,000)	(64,000)
Repayments of capital lease obligations	(4,891)	(3,267)
Net cash used in financing activities	(37,007)	(31,443)
Net decrease in cash and restricted cash	(31,878)	(18,746)
Cash and restricted cash, beginning of year	44,710	37,405
Cash and restricted cash, end of period	$ 12,832	$ 18,659

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Basis of Presentation And Significant Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation As used herein, the "Company,” “we,” “us,” or “our” refers to Selective Insurance Group, Inc. (the "Parent"), and its subsidiaries, except as expressly indicated or unless the context otherwise requires. Our interim unaudited consolidated financial statements (“Financial Statements”) have been prepared by us in conformity with U.S. generally accepted accounting principles (“GAAP”) and the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding interim financial reporting. The preparation of the Financial Statements in conformity with GAAP requires us 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. All significant intercompany accounts and transactions between the Parent and its subsidiaries are eliminated in consolidation. 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 2. "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. Our Financial Statements reflect all adjustments that, in our opinion, are normal, recurring, and necessary for a fair presentation of our results of operations and financial condition. Our Financial Statements cover the third quarters ended September 30, 2018 (“ Third Quarter 2018 ”) and September 30, 2017 (“ Third Quarter 2017 ”) and the nine -month periods ended September 30, 2018 (" Nine Months 2018 ") and September 30, 2017 (" Nine Months 2017 "). The Financial Statements do not include all of the information and disclosures required by GAAP and the SEC for audited annual financial statements. Results of operations for any interim period are not necessarily indicative of results for a full year. Consequently, our Financial Statements should be read in conjunction with the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2017 (“ 2017 Annual Report”) filed with the SEC.

Accounting Pronouncements

Accounting Pronouncements	9 Months Ended
	Sep. 30, 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 "Unrealized losses on equity securities" on our Consolidated Statements of Income. See Note 4 (j) below for information regarding unrealized equity losses recognized in income in Third Quarter and Nine Months 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 impact 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 Sheet. 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 Nine Months 2017 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 3. "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: September 30, 2017 ($ in thousands) Prior to Adoption After Adoption Undistributed gains of equity method investments $ (5,157 ) (4,247 ) Distributions in excess of current year income of equity method investments — 552 Decrease (increase) in other assets 12,678 (6,304 ) Net cash provided by operating activities 307,838 290,318 Distributions from other investments 18,503 17,041 Net cash used in investing activities (276,159 ) (277,621 ) 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 should 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 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 balance sheet for the first time. However, these increases will not have a material impact to our financial condition. 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 on 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. 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 nonemployees. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. We do not anticipate the adoption of this guidance to 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	9 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Information [Abstract]
Statements of Cash Flow	Statements of Cash Flows Supplemental cash flow information was as follows: Nine Months ended September 30, ($ in thousands) 2018 2017 Cash paid during the period for: Interest $ 15,449 15,356 Federal income tax 7,193 39,000 Non-cash items: Corporate actions related to fixed income securities, AFS 1 32,757 6,192 Corporate actions related to equity securities 1 944 4,725 Assets acquired under capital lease arrangements 4,114 278 1 Examples of such 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) September 30, 2018 December 31, 2017 Cash $ 446 534 Restricted cash 12,386 44,176 Total cash and restricted cash shown in the Statements of Cash Flows $ 12,832 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	9 Months Ended
	Sep. 30, 2018
Investments [Abstract]
Investments	Investments (a) Information regarding our held-to-maturity ("HTM") fixed income securities as of September 30, 2018 and December 31, 2017 was as follows: September 30, 2018 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states and political subdivisions $ 21,834 36 21,870 526 — 22,396 Corporate securities 22,798 (86 ) 22,712 1,132 — 23,844 Total HTM fixed income securities $ 44,632 (50 ) 44,582 1,658 — 46,240 December 31, 2017 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states 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. (b) Information regarding our AFS securities as of September 30, 2018 and December 31, 2017 was as follows: September 30, 2018 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 97,304 306 (1,148 ) 96,462 Foreign government 18,015 88 (120 ) 17,983 Obligations of states and political subdivisions 1,161,322 10,848 (7,261 ) 1,164,909 Corporate securities 1,662,613 6,342 (19,302 ) 1,649,653 Collateralized loan obligations and other asset-backed securities ("CLO and other ABS") 772,738 4,571 (2,540 ) 774,769 Commercial mortgage-backed securities ("CMBS") 495,208 328 (5,987 ) 489,549 Residential mortgage-backed securities (“RMBS”) 1,009,764 2,670 (15,603 ) 996,831 Total AFS securities $ 5,216,964 25,153 (51,961 ) 5,190,156 December 31, 2017 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair 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 other-than-temporary impairment ("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 with the adoption of new accounting guidance through which unrealized gains and losses on equity securities are no longer recognized in AOCI, but are instead recognized through income. Refer to Note 2. "Adoption of Accounting Pronouncements" for additional information regarding the adoption of ASU 2016-01. (c) The severity of impairment on securities in an unrealized/unrecognized loss position averaged approximately 2% of amortized cost at September 30, 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 of unrealized/unrecognized losses at September 30, 2018 , and $0.1 million of unrealized/unrecognized losses at December 31, 2017 . September 30, 2018 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 Fair Value Unrealized 1 AFS fixed income securities: U.S. government and government agencies $ 26,414 (843 ) 8,497 (305 ) 34,911 (1,148 ) Foreign government 7,281 (120 ) — — 7,281 (120 ) Obligations of states and political subdivisions 411,980 (7,008 ) 6,397 (253 ) 418,377 (7,261 ) Corporate securities 1,140,349 (19,052 ) 6,373 (250 ) 1,146,722 (19,302 ) CLO and other ABS 497,809 (2,479 ) 4,335 (61 ) 502,144 (2,540 ) CMBS 376,359 (5,940 ) 2,340 (47 ) 378,699 (5,987 ) RMBS 699,336 (14,727 ) 19,183 (876 ) 718,519 (15,603 ) Total AFS securities $ 3,159,528 (50,169 ) 47,125 (1,792 ) 3,206,653 (51,961 ) December 31, 2017 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 Fair Value Unrealized 1 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 $ 878,126 (4,961 ) 35,686 (397 ) 913,812 (5,358 ) 1 Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI. The increase in the less than 12 months unrealized loss position was due to higher interest rates, with a 94-basis point increase in 2-year U.S. Treasury Note yields and a 66-basis point increase in 10-year U.S. Treasury Note yields during the nine-month period ending September 30, 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 in accordance with our review of these securities under our OTTI policy, as described in Note 2. “Summary of Significant Accounting Policies” within Item 8. “Financial Statements and Supplementary Data.” of our 2017 Annual Report, 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. (d) Fixed income securities at September 30, 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 September 30, 2018 : AFS HTM ($ in thousands) Fair Value Carrying Value Fair Value Due in one year or less $ 176,545 14,017 14,150 Due after one year through five years 2,107,663 20,518 21,926 Due after five years through 10 years 2,759,167 10,047 10,164 Due after 10 years 146,781 — — Total fixed income securities $ 5,190,156 44,582 46,240 (e) The following table summarizes our other investment portfolio by strategy: Other Investments September 30, 2018 December 31, 2017 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Alternative Investments Private equity $ 75,508 99,346 174,854 52,251 99,026 151,277 Private credit 37,525 85,747 123,272 37,743 94,959 132,702 Real assets 25,214 33,088 58,302 25,379 27,014 52,393 Total alternative investments 138,247 218,181 356,428 115,373 220,999 336,372 Other securities 25,683 — 25,683 16,895 — 16,895 Total other investments $ 163,930 218,181 382,111 132,268 220,999 353,267 1 The maximum exposure to loss includes both the carry 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. We do not have a future obligation to fund losses or debts on behalf of the investments above; 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 table sets forth gross summarized financial information for our other investments portfolio, including the portion not owned by us. The majority of these investments are carried under the equity method of accounting. The last line of the table below reflects our share of the aggregate income or loss, 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 for the three- and nine -month periods ended June 30 is included in our Third Quarter and Nine Months results. This information is as follows: Income Statement Information Quarter ended September 30, Nine Months ended September 30, ($ in millions) 2018 2017 2018 2017 Net investment income (loss) $ 11.9 0.6 (29.9 ) (61.8 ) Realized gains (losses) 124.8 43.3 1,348.3 (261.0 ) Net change in unrealized appreciation 1,434.3 1,296.3 695.8 3,186.3 Net gain $ 1,571.0 1,340.2 2,014.2 2,863.5 Selective’s insurance subsidiaries’ alternative investments gain $ 7.1 2.7 10.6 9.5 (f) 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 September 30, 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 September 30, 2018 : ($ in millions) FHLBI Collateral FHLBNY Collateral State and Regulatory Deposits Total U.S. government and government agencies $ — — 22.2 22.2 Obligations of states and political subdivisions — — 3.8 3.8 CMBS 7.2 9.4 — 16.6 RMBS 57.8 76.3 — 134.1 Total pledged as collateral $ 65.0 85.7 26.0 176.7 (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-backed investments, as of September 30, 2018 or December 31, 2017 . (h) The components of pre-tax net investment income earned were as follows: Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Fixed income securities $ 45,088 38,865 130,903 113,424 Equity securities 2,079 1,605 5,876 4,492 Short-term investments 867 396 2,001 1,023 Other investments 7,211 2,659 10,868 9,493 Investment expenses (2,802 ) (3,079 ) (8,421 ) (9,137 ) Net investment income earned $ 52,443 40,446 141,227 119,295 (i) OTTI charges were $1.4 million and $0.1 million in Third Quarter 2018 and Third Quarter 2017 , respectively, and $5.5 million and $4.8 million in Nine Months 2018 and Nine Months 2017 , respectively. All of the OTTI charges in 2018 and a majority of the charges in 2017 were related to securities for which we had the intent to sell, with each security type's charge not exceeding 1% of its amortized cost. For a discussion of our evaluation for OTTI, refer to Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2017 Annual Report. (j) Net realized and unrealized gains and losses (excluding OTTI charges) for Third Quarter and Nine Months 2018 and 2017 included the following: Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Net realized (losses) gains on the disposals of securities: Fixed income securities $ (9,413 ) 1,996 (13,922 ) 6,566 Equity securities 8,665 4,875 17,960 5,225 Short-term investments 2 — 1 — Other investments (5 ) — (5 ) 461 Net realized gains on the disposal of securities (751 ) 6,871 4,034 12,252 OTTI charges (1,426 ) (73 ) (5,459 ) (4,765 ) Net realized (losses) gains (2,177 ) 6,798 (1,425 ) 7,487 Unrealized (losses) recognized in income on equity securities 1 (2,610 ) — (15,563 ) — Total net realized and unrealized investment (losses) gains $ (4,787 ) 6,798 $ (16,988 ) 7,487 1 Includes unrealized holding gains (losses) of: (i) $5.5 million in Third Quarter 2018 and $4.2 million in Nine Months 2018 on equity securities remaining in our portfolio as of September 30, 2018 ; and (ii) $(8.1) million in Third Quarter 2018 and $(19.8) million in Nine Months 2018 on equity securities sold during the respective periods. The components of net realized gains on disposals of securities for the periods indicated were as follows: Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 HTM fixed income securities Gains $ — — 2 44 Losses — — — (1 ) AFS fixed income securities Gains 462 2,070 5,056 8,337 Losses (9,875 ) (74 ) (18,980 ) (1,814 ) Equity securities Gains 10,584 4,875 20,209 5,225 Losses (1,919 ) — (2,249 ) — Short-term investments Gains 3 — 6 2 Losses (1 ) — (5 ) (2 ) Other investments Gains — — — 480 Losses (5 ) — (5 ) (19 ) Total net realized gains (losses) on disposals of securities $ (751 ) 6,871 4,034 12,252 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 sales of AFS fixed income securities were $444.4 million and $94.9 million in Third Quarter 2018 and Third Quarter 2017 , respectively, and $1,382.7 million and $812.0 million in Nine Months 2018 and Nine Months 2017 , respectively. Proceeds from the sales of equity securities were $36.1 million and $12.7 million in Third Quarter 2018 and Third Quarter 2017 , respectively, and $79.7 million and $19.0 million in Nine Months 2018 and Nine Months 2017 , respectively.

Indebtedness Indebtedness

Indebtedness Indebtedness	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt Disclosure	Indebtedness Our long-term debt balance has not changed materially since December 31, 2017 . However, Selective Insurance Company of America ("SICA") borrowed the following short-term funds in the first quarter of 2018 from the FHLBNY: • On February 27, 2018, SICA borrowed $75 million at an interest rate of 1.75% . This borrowing was repaid on March 20, 2018; and • On March 28, 2018, SICA borrowed $55 million at an interest rate of 1.98% . This borrowing was repaid on April 18, 2018. For detailed information on our indebtedness, see Note 10. "Indebtedness" in Item 8. "Financial Statements and Supplementary Data." of our 2017 Annual Report.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Our financial assets are measured at fair value as disclosed on the Consolidated Balance Sheets. The fair values of our long-term debt are provided in this footnote and the related carry values have changed by less than 1% during Nine Months 2018 . For a discussion of the fair value and hierarchy of the techniques used to value our financial assets and liabilities, refer to Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2017 Annual Report. The following tables provide quantitative disclosures of our financial assets that were measured and recorded at fair value at September 30, 2018 and December 31, 2017 : September 30, 2018 Fair Value Measurements Using ($ in thousands) Assets 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 $ 96,462 76,760 19,702 — Foreign government 17,983 — 17,983 — Obligations of states and political subdivisions 1,164,909 — 1,164,909 — Corporate securities 1,649,653 — 1,649,653 — CLO and other ABS 774,769 — 770,628 4,141 CMBS 489,549 — 489,549 — RMBS 996,831 — 996,831 — Total AFS fixed income securities 5,190,156 76,760 5,109,255 4,141 Equity securities: Common stock 2 154,845 124,445 — — Preferred stock 3,022 3,022 — — Total equity securities 157,867 127,467 — — Short-term investments 304,572 303,572 1,000 — Total assets measured at fair value $ 5,652,595 507,799 5,110,255 4,141 December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets 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 2 167,757 138,640 — 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 Investments amounting to $30.4 million at September 30, 2018 , and $23.7 million at December 31, 2017 , were measured at fair value using net asset value per share (or its practical expedient) and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to total assets measured at fair value. There were no material changes in the fair value of securities measured using Level 3 prices in Nine Months 2017 . The following table provides a summary of Level 3 changes in Nine Months 2018 : September 30, 2018 ($ in thousands) CMBS Common Stock CLO and Other ABS Fair value, December 31, 2017 $ 6,554 5,398 — Total net (losses) gains for the period included in: OCI — — — Net income — — — Purchases — — 4,141 Sales — — — Issuances — — — Settlements — — — Transfers into Level 3 — — — Transfers out of Level 3 (6,554 ) (5,398 ) — Fair value, September 30, 2018 $ — — 4,141 The following tables provide quantitative information regarding our financial assets and liabilities that were disclosed at fair value at September 30, 2018 and December 31, 2017 : September 30, 2018 Fair Value Measurements Using ($ in thousands) Assets/ 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 $ 22,396 — 22,396 — Corporate securities 23,844 — 11,583 12,261 Total HTM fixed income securities $ 46,240 — 33,979 12,261 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 57,733 — 57,733 — 6.70% Senior Notes 106,760 — 106,760 — 5.875% Senior Notes 184,778 184,778 — — 1.61% borrowings from FHLBNY 23,936 — 23,936 — 1.56% borrowings from FHLBNY 23,871 — 23,871 — 3.03% borrowings from FHLBI 57,795 — 57,795 — Total long-term debt $ 454,873 184,778 270,095 — December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets/ 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	9 Months Ended
	Sep. 30, 2018
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The following table contains a listing of direct, assumed, and ceded reinsurance amounts for premiums written, premiums earned, and loss and loss expenses incurred for the periods indicated. For more information concerning reinsurance, refer to Note 8. “Reinsurance” in Item 8. “Financial Statements and Supplementary Data.” of our 2017 Annual Report. Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Premiums written: Direct $ 752,834 706,918 $ 2,220,431 2,097,146 Assumed 7,084 8,506 19,891 20,685 Ceded (108,250 ) (111,147 ) (308,846 ) (301,036 ) Net $ 651,668 604,277 $ 1,931,476 1,816,795 Premiums earned: Direct $ 706,497 666,048 $ 2,086,953 1,967,364 Assumed 6,484 7,623 19,220 19,465 Ceded (98,704 ) (101,616 ) (295,232 ) (285,890 ) Net $ 614,277 572,055 $ 1,810,941 1,700,939 Loss and loss expenses incurred: Direct $ 477,427 455,728 $ 1,289,357 1,187,400 Assumed 6,529 5,420 16,897 17,623 Ceded (104,757 ) (116,561 ) (175,786 ) (201,405 ) Net $ 379,199 344,587 $ 1,130,468 1,003,618 Ceded premiums and losses related to our participation in the NFIP, under which 100% of our flood premiums, losses, and loss expenses are ceded to the NFIP, are as follows: Ceded to NFIP Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Ceded premiums written $ (70,100 ) (68,132 ) $ (193,110 ) (188,274 ) Ceded premiums earned (61,448 ) (59,847 ) (180,582 ) (174,779 ) Ceded loss and loss expenses incurred (89,396 ) (112,994 ) (115,376 ) (134,675 )

Reserve for Loss and Loss Expen

Reserve for Loss and Loss Expense	9 Months Ended
	Sep. 30, 2018
Insurance Loss Reserves [Abstract]
Liability for Future Policy Benefits and Unpaid Claims Disclosure	Reserve for Loss and Loss Expense The table below provides a roll forward of reserve for loss and loss expense balances: Nine Months ended September 30, ($ in thousands) 2018 2017 Gross reserve for loss and loss expense, at beginning of year $ 3,771,240 3,691,719 Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of year 585,855 611,200 Net reserve for loss and loss expense, at beginning of year 3,185,385 3,080,519 Incurred loss and loss expense for claims occurring in the: Current year 1,148,032 1,037,079 Prior years (17,564 ) (33,461 ) Total incurred loss and loss expense 1,130,468 1,003,618 Paid loss and loss expense for claims occurring in the: Current year 369,036 314,686 Prior years 610,734 581,186 Total paid loss and loss expense 979,770 895,872 Net reserve for loss and loss expense, at end of period 3,336,083 3,188,265 Add: Reinsurance recoverable on unpaid loss and loss expense, at end of period 589,072 647,535 Gross reserve for loss and loss expense at end of period $ 3,925,155 3,835,800 The $111.0 million increase in current year loss and loss expense incurred illustrated in the table above was primarily driven by: (i) non-catastrophe property losses; (ii) an increase in current year loss costs on our commercial automobile line of business; and (iii) an increase in exposure due to premium growth. Non-catastrophe property losses, which increased $61.9 million , to $278.5 million , in Nine Months 2018 , were partially related to the early January 2018 deep freeze in our footprint states and a relatively large number of fire losses over the course of the year. Prior year development in Nine Months 2018 of $17.6 million included $24.0 million of favorable casualty development, partially offset by $6.4 million of unfavorable property development. The favorable casualty development included $53.0 million of development in our workers compensation line of business and $8.0 million in our general liability line of business, partially offset by unfavorable development of $25.0 million in our commercial automobile line of business and $12.0 million in our excess and surplus ("E&S") casualty lines. Prior year development in Nine Months 2017 of $33.5 million was primarily driven by favorable prior year casualty reserve development of $48.3 million in our general liability line of business and $29.3 million in our workers compensation line of business. This was partially offset by unfavorable development of $26.0 million in our commercial automobile line of business, $10.0 million in our E&S segment, and $4.0 million in our personal automobile line of business. For a discussion of the trends and recent developments impacting these lines, refer to the "Critical Accounting Policies and Estimates" section of Item 7. "Management's Discussion and Analysis of Financial Condition and Results of Operations." in our 2017 Annual Report.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 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, policyholder dividends, policy acquisition costs, and other underwriting expenses), and combined ratios. • Our Investments segment is evaluated based on after-tax net investment income and net realized 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. The following summaries present revenues (net investment income and net realized and unrealized gains on investments in the case of the Investments segment) and pre-tax income for the individual segments: Revenue by Segment Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Standard Commercial Lines: Net premiums earned: Commercial automobile $ 124,862 111,711 365,197 327,156 Workers compensation 78,784 77,580 237,628 236,366 General liability 154,974 141,059 457,805 422,546 Commercial property 83,056 78,151 245,544 232,594 Businessowners’ policies 25,994 25,019 77,414 74,853 Bonds 8,778 7,420 25,247 20,904 Other 4,608 4,310 13,597 12,839 Miscellaneous income 2,228 1,712 6,936 7,588 Total Standard Commercial Lines revenue 483,284 446,962 1,429,368 1,334,846 Standard Personal Lines: Net premiums earned: Personal automobile 42,772 38,612 125,024 113,225 Homeowners 32,293 32,215 96,717 97,382 Other 2,092 1,774 5,349 4,867 Miscellaneous income 310 282 959 938 Total Standard Personal Lines revenue 77,467 72,883 228,049 216,412 E&S Lines: Net premiums earned: Casualty lines 42,179 40,090 120,098 117,056 Property lines 13,885 14,114 41,321 41,151 Miscellaneous income — — 1 — Total E&S Lines revenue 56,064 54,204 161,420 158,207 Investments: Net investment income 52,443 40,446 141,227 119,295 Net realized and unrealized investment (losses) gains (4,787 ) 6,798 (16,988 ) 7,487 Total Investments revenue 47,656 47,244 124,239 126,782 Total revenues $ 664,471 621,293 1,943,076 1,836,247 Income Before and After Federal Income Tax Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Standard Commercial Lines: Underwriting gain, before federal income tax $ 26,333 35,329 74,153 112,634 Underwriting gain, after federal income tax 20,803 22,964 58,581 73,212 Combined ratio 94.5 % 92.1 94.8 91.5 Standard Personal Lines: Underwriting gain, before federal income tax $ 3,158 8,179 6,457 7,517 Underwriting gain, after federal income tax 2,495 5,316 5,101 4,886 Combined ratio 95.9 % 88.7 97.2 96.5 E&S Lines: Underwriting gain (loss), before federal income tax $ 3,506 (11,063 ) (4,848 ) (8,174 ) Underwriting gain (loss), after federal income tax 2,770 (7,191 ) (3,830 ) (5,313 ) Combined ratio 93.7 % 120.4 103.0 105.2 Investments: Net investment income $ 52,443 40,446 141,227 119,295 Net realized and unrealized investment (losses) gains (4,787 ) 6,798 (16,988 ) 7,487 Total investment income, before federal income tax 47,656 47,244 124,239 126,782 Tax on investment income 8,562 13,236 21,405 34,572 Total investment income, after federal income tax $ 39,094 34,008 102,834 92,210 Reconciliation of Segment Results to Income Before Federal Income Tax Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Underwriting gain (loss) Standard Commercial Lines $ 26,333 35,329 74,153 112,634 Standard Personal Lines 3,158 8,179 6,457 7,517 E&S Lines 3,506 (11,063 ) (4,848 ) (8,174 ) Investment income 47,656 47,244 124,239 126,782 Total all segments 80,653 79,689 200,001 238,759 Interest expense (6,073 ) (6,085 ) (18,350 ) (18,272 ) Corporate expenses (7,450 ) (6,289 ) (22,065 ) (26,669 ) Income, before federal income tax $ 67,130 67,315 159,586 193,818

Retirement Plans

Retirement Plans	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Retirement Plans	Retirement Plans SICA's primary pension plan is the Retirement Income Plan for Selective Insurance Company of America (the “Pension Plan”). SICA also sponsors the Supplemental Excess Retirement Plan (the “Excess Plan”) and a life insurance benefit plan. All plans are closed to new entrants and benefits ceased accruing under the Pension Plan and the Excess Plan after March 31, 2016 . For more information concerning SICA's retirement plans, refer to Note 14. “Retirement Plans” in Item 8. “Financial Statements and Supplementary Data.” of our 2017 Annual Report. The following tables provide information regarding the Pension Plan: Pension Plan Pension Plan Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Net Periodic Benefit Cost: Interest cost $ 3,095 3,111 9,285 9,332 Expected return on plan assets (5,681 ) (4,854 ) (17,044 ) (14,563 ) Amortization of unrecognized net actuarial loss 494 481 1,481 1,444 Total net periodic benefit cost 1 $ (2,092 ) (1,262 ) (6,278 ) (3,787 ) 1 The components of net periodic benefit cost are included within "Loss and loss expense incurred" and "Other insurance expenses" on the Consolidated Statements of Income. Pension Plan Nine Months ended September 30, 2018 2017 Weighted-Average Expense Assumptions: Discount rate 3.78 % 4.41 % Effective interest rate for calculation of interest cost 3.46 3.83 Expected return on plan assets 6.36 6.24

Comprehensive Income

Comprehensive Income	9 Months Ended
	Sep. 30, 2018
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Comprehensive Income	Comprehensive Income The components of comprehensive income, both gross and net of tax, for Third Quarter and Nine Months 2018 and 2017 are as follows: Third Quarter 2018 ($ in thousands) Gross Tax Net Net income $ 67,130 11,695 55,435 Components of other comprehensive loss: Unrealized losses on investment securities : Unrealized holding losses during period (21,565 ) (4,529 ) (17,036 ) Amounts reclassified into net income: HTM securities (8 ) (2 ) (6 ) Realized losses on disposals of AFS securities 10,839 2,276 8,563 Total unrealized losses on investment securities (10,734 ) (2,255 ) (8,479 ) Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 532 112 420 Total defined benefit pension and post-retirement plans 532 112 420 Other comprehensive loss (10,202 ) (2,143 ) (8,059 ) Comprehensive income $ 56,928 9,552 47,376 Third Quarter 2017 ($ in thousands) Gross Tax Net Net income $ 67,315 20,597 46,718 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 16,729 5,855 10,874 Non-credit portion of OTTI recognized in OCI 30 11 19 Amounts reclassified into net income: HTM securities (54 ) (19 ) (35 ) Non-credit OTTI 38 13 25 Realized gains on disposals of AFS securities (6,760 ) (2,366 ) (4,394 ) Total unrealized gains on investment securities 9,983 3,494 6,489 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 507 178 329 Total defined benefit pension and post-retirement plans 507 178 329 Other comprehensive income 10,490 3,672 6,818 Comprehensive income $ 77,805 24,269 53,536 Nine Months 2018 ($ in thousands) Gross Tax Net Net income $ 159,586 26,407 133,179 Components of other comprehensive loss: Unrealized losses on investment securities : Unrealized holding losses during period (130,873 ) (27,484 ) (103,389 ) Amounts reclassified into net income: HTM securities (28 ) (6 ) (22 ) Realized losses on disposals of AFS securities 18,258 3,834 14,424 Total unrealized losses on investment securities (112,643 ) (23,656 ) (88,987 ) Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,595 335 1,260 Total defined benefit pension and post-retirement plans 1,595 335 1,260 Other comprehensive loss (111,048 ) (23,321 ) (87,727 ) Comprehensive income $ 48,538 3,086 45,452 Nine Months 2017 ($ in thousands) Gross Tax Net Net income $ 193,818 55,234 138,584 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 78,401 27,440 50,961 Non-credit portion of OTTI recognized in OCI 36 13 23 Amounts reclassified into net income: HTM securities (146 ) (51 ) (95 ) Non-credit OTTI 38 13 25 Realized gains on disposals of AFS securities (7,135 ) (2,497 ) (4,638 ) Total unrealized gains on investment securities 71,194 24,918 46,276 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,522 533 989 Total defined benefit pension and post-retirement plans 1,522 533 989 Other comprehensive income 72,716 25,451 47,265 Comprehensive income $ 266,534 80,685 185,849 The balances of, and changes in, each component of AOCI (net of taxes) as of September 30, 2018 were as follows: September 30, 2018 Defined Benefit Pension and Post-Retirement Plans Net Unrealized Gains (Losses) on Investment Securities Total AOCI ($ in thousands) OTTI Related HTM Related All Other Investments Subtotal Balance, December 31, 2017 $ (59 ) (14 ) 80,648 80,575 (60,405 ) 20,170 Cumulative effect adjustments (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 — — (103,389 ) (103,389 ) — (103,389 ) Amounts reclassified from AOCI — (22 ) 14,424 14,402 1,260 15,662 Net current period OCI — (22 ) (88,965 ) (88,987 ) 1,260 (87,727 ) Balance, September 30, 2018 $ (71 ) (38 ) (21,109 ) (21,218 ) (71,358 ) (92,576 ) The reclassifications out of AOCI were as follows: Quarter ended September 30, Nine Months ended September 30, Affected Line Item in the Unaudited Consolidated Statements of Income ($ in thousands) 2018 2017 2018 2017 OTTI related Non-credit OTTI on disposed securities $ — 38 — 38 Net realized and unrealized (losses) gains — 38 — 38 Income before federal income tax — (13 ) — (13 ) Total federal income tax expense — 25 — 25 Net income HTM related Unrealized losses on HTM disposals $ 11 11 5 41 Net realized and unrealized (losses) gains Amortization of net unrealized gains on HTM securities (19 ) (65 ) (33 ) (187 ) Net investment income earned (8 ) (54 ) (28 ) (146 ) Income before federal income tax 2 19 6 51 Total federal income tax expense (6 ) (35 ) (22 ) (95 ) Net income Realized losses (gains) on AFS and OTTI Realized losses (gains) on AFS disposals and OTTI 10,839 (6,760 ) 18,258 (7,135 ) Net realized and unrealized (losses) gains 10,839 (6,760 ) 18,258 (7,135 ) Income before federal income tax (2,276 ) 2,366 (3,834 ) 2,497 Total federal income tax expense 8,563 (4,394 ) 14,424 (4,638 ) Net income Defined benefit pension and post-retirement life plans Net actuarial loss 112 110 337 331 Loss and loss expense incurred 420 397 1,258 1,191 Other insurance expenses Total defined benefit pension and post-retirement life 532 507 1,595 1,522 Income before federal income tax (112 ) (178 ) (335 ) (533 ) Total federal income tax expense 420 329 1,260 989 Net income Total reclassifications for the period $ 8,977 (4,075 ) 15,662 (3,719 ) Net income

Federal Income Taxes

Federal Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Tax Disclosure	Federal Income Taxes (a) On December 22, 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 continue to provide provisional amounts for loss reserve discounting because the Internal Revenue Service ("IRS") has not yet issued guidance with regard to the discount rates to be used under Tax Reform. For additional information, refer to Note 13. "Federal Income Taxes" in Item 8. "Financial Statements and Supplementary Data." of our 2017 Annual Report. We will continue to monitor IRS guidance to complete the analysis of loss reserve discounting. (b) A reconciliation of federal income tax on income at the corporate rate to the effective tax rate is as follows: Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Statutory tax rate 21 % 35 21 35 Tax at statutory rate $ 14,097 23,560 33,513 67,836 Tax-advantaged interest (1,338 ) (2,915 ) (4,242 ) (8,479 ) Dividends received deduction (107 ) (382 ) (443 ) (1,338 ) Stock-based compensation (415 ) (86 ) (2,963 ) (3,409 ) Other (542 ) 420 542 624 Federal income tax expense $ 11,695 20,597 26,407 55,234

Litigation

Litigation	9 Months Ended
	Sep. 30, 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 ten insurance subsidiaries ("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 September 30, 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.

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Hurricane Michael made landfall on October 10, 2018 in the Florida Panhandle as a powerful Category 4 hurricane and continued into Georgia and other southeastern states. While relatively early given the complexity of losses involved, we currently estimate our losses from this event to be approximately $10 million .

Accounting Pronouncements (Tabl

Accounting Pronouncements (Tables)	9 Months Ended
	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	September 30, 2017 ($ in thousands) Prior to Adoption After Adoption Undistributed gains of equity method investments $ (5,157 ) (4,247 ) Distributions in excess of current year income of equity method investments — 552 Decrease (increase) in other assets 12,678 (6,304 ) Net cash provided by operating activities 307,838 290,318 Distributions from other investments 18,503 17,041 Net cash used in investing activities (276,159 ) (277,621 )

Statements of Cash Flow (Tables

Statements of Cash Flow (Tables)	9 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Nine Months ended September 30, ($ in thousands) 2018 2017 Cash paid during the period for: Interest $ 15,449 15,356 Federal income tax 7,193 39,000 Non-cash items: Corporate actions related to fixed income securities, AFS 1 32,757 6,192 Corporate actions related to equity securities 1 944 4,725 Assets acquired under capital lease arrangements 4,114 278
Schedule of Cash and Restricted Cash	($ in thousands) September 30, 2018 December 31, 2017 Cash $ 446 534 Restricted cash 12,386 44,176 Total cash and restricted cash shown in the Statements of Cash Flows $ 12,832 44,710

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments [Line Items]
Schedule of Held-to-maturity Securities	September 30, 2018 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states and political subdivisions $ 21,834 36 21,870 526 — 22,396 Corporate securities 22,798 (86 ) 22,712 1,132 — 23,844 Total HTM fixed income securities $ 44,632 (50 ) 44,582 1,658 — 46,240 December 31, 2017 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states 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	September 30, 2018 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 97,304 306 (1,148 ) 96,462 Foreign government 18,015 88 (120 ) 17,983 Obligations of states and political subdivisions 1,161,322 10,848 (7,261 ) 1,164,909 Corporate securities 1,662,613 6,342 (19,302 ) 1,649,653 Collateralized loan obligations and other asset-backed securities ("CLO and other ABS") 772,738 4,571 (2,540 ) 774,769 Commercial mortgage-backed securities ("CMBS") 495,208 328 (5,987 ) 489,549 Residential mortgage-backed securities (“RMBS”) 1,009,764 2,670 (15,603 ) 996,831 Total AFS securities $ 5,216,964 25,153 (51,961 ) 5,190,156 December 31, 2017 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair 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, AFS	September 30, 2018 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 Fair Value Unrealized 1 AFS fixed income securities: U.S. government and government agencies $ 26,414 (843 ) 8,497 (305 ) 34,911 (1,148 ) Foreign government 7,281 (120 ) — — 7,281 (120 ) Obligations of states and political subdivisions 411,980 (7,008 ) 6,397 (253 ) 418,377 (7,261 ) Corporate securities 1,140,349 (19,052 ) 6,373 (250 ) 1,146,722 (19,302 ) CLO and other ABS 497,809 (2,479 ) 4,335 (61 ) 502,144 (2,540 ) CMBS 376,359 (5,940 ) 2,340 (47 ) 378,699 (5,987 ) RMBS 699,336 (14,727 ) 19,183 (876 ) 718,519 (15,603 ) Total AFS securities $ 3,159,528 (50,169 ) 47,125 (1,792 ) 3,206,653 (51,961 ) December 31, 2017 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 Fair Value Unrealized 1 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 $ 878,126 (4,961 ) 35,686 (397 ) 913,812 (5,358 ) 1 Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI.
Schedule of Fixed Maturity Securities By Contractual Maturities	AFS HTM ($ in thousands) Fair Value Carrying Value Fair Value Due in one year or less $ 176,545 14,017 14,150 Due after one year through five years 2,107,663 20,518 21,926 Due after five years through 10 years 2,759,167 10,047 10,164 Due after 10 years 146,781 — — Total fixed income securities $ 5,190,156 44,582 46,240
Schedule of Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy	Other Investments September 30, 2018 December 31, 2017 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Alternative Investments Private equity $ 75,508 99,346 174,854 52,251 99,026 151,277 Private credit 37,525 85,747 123,272 37,743 94,959 132,702 Real assets 25,214 33,088 58,302 25,379 27,014 52,393 Total alternative investments 138,247 218,181 356,428 115,373 220,999 336,372 Other securities 25,683 — 25,683 16,895 — 16,895 Total other investments $ 163,930 218,181 382,111 132,268 220,999 353,267 1 The maximum exposure to loss includes both the carry 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.
Schedule of Aggregated Summarized Income Statement Financial Information For Partnerships In Our Alternative Investment Portfolio	Income Statement Information Quarter ended September 30, Nine Months ended September 30, ($ in millions) 2018 2017 2018 2017 Net investment income (loss) $ 11.9 0.6 (29.9 ) (61.8 ) Realized gains (losses) 124.8 43.3 1,348.3 (261.0 ) Net change in unrealized appreciation 1,434.3 1,296.3 695.8 3,186.3 Net gain $ 1,571.0 1,340.2 2,014.2 2,863.5 Selective’s insurance subsidiaries’ alternative investments gain $ 7.1 2.7 10.6 9.5
Schedule of Securities Pledged As Collateral	($ in millions) FHLBI Collateral FHLBNY Collateral State and Regulatory Deposits Total U.S. government and government agencies $ — — 22.2 22.2 Obligations of states and political subdivisions — — 3.8 3.8 CMBS 7.2 9.4 — 16.6 RMBS 57.8 76.3 — 134.1 Total pledged as collateral $ 65.0 85.7 26.0 176.7
Schedule of Pre-Tax Net Investment Income Earned	Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Fixed income securities $ 45,088 38,865 130,903 113,424 Equity securities 2,079 1,605 5,876 4,492 Short-term investments 867 396 2,001 1,023 Other investments 7,211 2,659 10,868 9,493 Investment expenses (2,802 ) (3,079 ) (8,421 ) (9,137 ) Net investment income earned $ 52,443 40,446 141,227 119,295
Schedule of Components of Net Realized and Unrealized Gains and Losses Excluding OTTI Charges	Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Net realized (losses) gains on the disposals of securities: Fixed income securities $ (9,413 ) 1,996 (13,922 ) 6,566 Equity securities 8,665 4,875 17,960 5,225 Short-term investments 2 — 1 — Other investments (5 ) — (5 ) 461 Net realized gains on the disposal of securities (751 ) 6,871 4,034 12,252 OTTI charges (1,426 ) (73 ) (5,459 ) (4,765 ) Net realized (losses) gains (2,177 ) 6,798 (1,425 ) 7,487 Unrealized (losses) recognized in income on equity securities 1 (2,610 ) — (15,563 ) — Total net realized and unrealized investment (losses) gains $ (4,787 ) 6,798 $ (16,988 ) 7,487 1 Includes unrealized holding gains (losses) of: (i) $5.5 million in Third Quarter 2018 and $4.2 million in Nine Months 2018 on equity securities remaining in our portfolio as of September 30, 2018 ; and (ii) $(8.1) million in Third Quarter 2018 and $(19.8) million in Nine Months 2018 on equity securities sold during the respective periods.
Schedule of Realized Gains and Losses on Disposals of Securities	Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 HTM fixed income securities Gains $ — — 2 44 Losses — — — (1 ) AFS fixed income securities Gains 462 2,070 5,056 8,337 Losses (9,875 ) (74 ) (18,980 ) (1,814 ) Equity securities Gains 10,584 4,875 20,209 5,225 Losses (1,919 ) — (2,249 ) — Short-term investments Gains 3 — 6 2 Losses (1 ) — (5 ) (2 ) Other investments Gains — — — 480 Losses (5 ) — (5 ) (19 ) Total net realized gains (losses) on disposals of securities $ (751 ) 6,871 4,034 12,252

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Schedule of Quantitative Disclosures of Our Financial Assets That Were Measured At Fair Value	September 30, 2018 Fair Value Measurements Using ($ in thousands) Assets 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 $ 96,462 76,760 19,702 — Foreign government 17,983 — 17,983 — Obligations of states and political subdivisions 1,164,909 — 1,164,909 — Corporate securities 1,649,653 — 1,649,653 — CLO and other ABS 774,769 — 770,628 4,141 CMBS 489,549 — 489,549 — RMBS 996,831 — 996,831 — Total AFS fixed income securities 5,190,156 76,760 5,109,255 4,141 Equity securities: Common stock 2 154,845 124,445 — — Preferred stock 3,022 3,022 — — Total equity securities 157,867 127,467 — — Short-term investments 304,572 303,572 1,000 — Total assets measured at fair value $ 5,652,595 507,799 5,110,255 4,141 December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets 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 2 167,757 138,640 — 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 Investments amounting to $30.4 million at September 30, 2018 , and $23.7 million at December 31, 2017 , were measured at fair value using net asset value per share (or its practical expedient) and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to total assets measured at fair value
Schedule of Changes in Fair Value of Securities Using Level 3 Inputs	September 30, 2018 ($ in thousands) CMBS Common Stock CLO and Other ABS Fair value, December 31, 2017 $ 6,554 5,398 — Total net (losses) gains for the period included in: OCI — — — Net income — — — Purchases — — 4,141 Sales — — — Issuances — — — Settlements — — — Transfers into Level 3 — — — Transfers out of Level 3 (6,554 ) (5,398 ) — Fair value, September 30, 2018 $ — — 4,141
Schedule of Quantitative Information of Our Financial Assets and Liabilities That Were Disclosed at Fair Value	September 30, 2018 Fair Value Measurements Using ($ in thousands) Assets/ 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 $ 22,396 — 22,396 — Corporate securities 23,844 — 11,583 12,261 Total HTM fixed income securities $ 46,240 — 33,979 12,261 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 57,733 — 57,733 — 6.70% Senior Notes 106,760 — 106,760 — 5.875% Senior Notes 184,778 184,778 — — 1.61% borrowings from FHLBNY 23,936 — 23,936 — 1.56% borrowings from FHLBNY 23,871 — 23,871 — 3.03% borrowings from FHLBI 57,795 — 57,795 — Total long-term debt $ 454,873 184,778 270,095 — December 31, 2017 Fair Value Measurements Using ($ in thousands) Assets/ 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)	9 Months Ended
	Sep. 30, 2018
Reinsurance Disclosures [Abstract]
Schedule of List Of Direct, Assumed, And Ceded Reinsurance Amounts	Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Premiums written: Direct $ 752,834 706,918 $ 2,220,431 2,097,146 Assumed 7,084 8,506 19,891 20,685 Ceded (108,250 ) (111,147 ) (308,846 ) (301,036 ) Net $ 651,668 604,277 $ 1,931,476 1,816,795 Premiums earned: Direct $ 706,497 666,048 $ 2,086,953 1,967,364 Assumed 6,484 7,623 19,220 19,465 Ceded (98,704 ) (101,616 ) (295,232 ) (285,890 ) Net $ 614,277 572,055 $ 1,810,941 1,700,939 Loss and loss expenses incurred: Direct $ 477,427 455,728 $ 1,289,357 1,187,400 Assumed 6,529 5,420 16,897 17,623 Ceded (104,757 ) (116,561 ) (175,786 ) (201,405 ) Net $ 379,199 344,587 $ 1,130,468 1,003,618
Schedule of Ceded Premiums and Losses Related to Flood Operations	Ceded to NFIP Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Ceded premiums written $ (70,100 ) (68,132 ) $ (193,110 ) (188,274 ) Ceded premiums earned (61,448 ) (59,847 ) (180,582 ) (174,779 ) Ceded loss and loss expenses incurred (89,396 ) (112,994 ) (115,376 ) (134,675 )

Reserve for Loss and Loss Exp_2

Reserve for Loss and Loss Expense (Tables)	9 Months Ended
	Sep. 30, 2018
Insurance Loss Reserves [Abstract]
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense	Nine Months ended September 30, ($ in thousands) 2018 2017 Gross reserve for loss and loss expense, at beginning of year $ 3,771,240 3,691,719 Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of year 585,855 611,200 Net reserve for loss and loss expense, at beginning of year 3,185,385 3,080,519 Incurred loss and loss expense for claims occurring in the: Current year 1,148,032 1,037,079 Prior years (17,564 ) (33,461 ) Total incurred loss and loss expense 1,130,468 1,003,618 Paid loss and loss expense for claims occurring in the: Current year 369,036 314,686 Prior years 610,734 581,186 Total paid loss and loss expense 979,770 895,872 Net reserve for loss and loss expense, at end of period 3,336,083 3,188,265 Add: Reinsurance recoverable on unpaid loss and loss expense, at end of period 589,072 647,535 Gross reserve for loss and loss expense at end of period $ 3,925,155 3,835,800

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of Revenue By Segment	Revenue by Segment Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Standard Commercial Lines: Net premiums earned: Commercial automobile $ 124,862 111,711 365,197 327,156 Workers compensation 78,784 77,580 237,628 236,366 General liability 154,974 141,059 457,805 422,546 Commercial property 83,056 78,151 245,544 232,594 Businessowners’ policies 25,994 25,019 77,414 74,853 Bonds 8,778 7,420 25,247 20,904 Other 4,608 4,310 13,597 12,839 Miscellaneous income 2,228 1,712 6,936 7,588 Total Standard Commercial Lines revenue 483,284 446,962 1,429,368 1,334,846 Standard Personal Lines: Net premiums earned: Personal automobile 42,772 38,612 125,024 113,225 Homeowners 32,293 32,215 96,717 97,382 Other 2,092 1,774 5,349 4,867 Miscellaneous income 310 282 959 938 Total Standard Personal Lines revenue 77,467 72,883 228,049 216,412 E&S Lines: Net premiums earned: Casualty lines 42,179 40,090 120,098 117,056 Property lines 13,885 14,114 41,321 41,151 Miscellaneous income — — 1 — Total E&S Lines revenue 56,064 54,204 161,420 158,207 Investments: Net investment income 52,443 40,446 141,227 119,295 Net realized and unrealized investment (losses) gains (4,787 ) 6,798 (16,988 ) 7,487 Total Investments revenue 47,656 47,244 124,239 126,782 Total revenues $ 664,471 621,293 1,943,076 1,836,247
Schedule of Income Before and After Federal Income Tax	Income Before and After Federal Income Tax Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Standard Commercial Lines: Underwriting gain, before federal income tax $ 26,333 35,329 74,153 112,634 Underwriting gain, after federal income tax 20,803 22,964 58,581 73,212 Combined ratio 94.5 % 92.1 94.8 91.5 Standard Personal Lines: Underwriting gain, before federal income tax $ 3,158 8,179 6,457 7,517 Underwriting gain, after federal income tax 2,495 5,316 5,101 4,886 Combined ratio 95.9 % 88.7 97.2 96.5 E&S Lines: Underwriting gain (loss), before federal income tax $ 3,506 (11,063 ) (4,848 ) (8,174 ) Underwriting gain (loss), after federal income tax 2,770 (7,191 ) (3,830 ) (5,313 ) Combined ratio 93.7 % 120.4 103.0 105.2 Investments: Net investment income $ 52,443 40,446 141,227 119,295 Net realized and unrealized investment (losses) gains (4,787 ) 6,798 (16,988 ) 7,487 Total investment income, before federal income tax 47,656 47,244 124,239 126,782 Tax on investment income 8,562 13,236 21,405 34,572 Total investment income, after federal income tax $ 39,094 34,008 102,834 92,210
Schedule of Reconciliation of Segment Results to Income Before Federal Income Tax	Reconciliation of Segment Results to Income Before Federal Income Tax Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Underwriting gain (loss) Standard Commercial Lines $ 26,333 35,329 74,153 112,634 Standard Personal Lines 3,158 8,179 6,457 7,517 E&S Lines 3,506 (11,063 ) (4,848 ) (8,174 ) Investment income 47,656 47,244 124,239 126,782 Total all segments 80,653 79,689 200,001 238,759 Interest expense (6,073 ) (6,085 ) (18,350 ) (18,272 ) Corporate expenses (7,450 ) (6,289 ) (22,065 ) (26,669 ) Income, before federal income tax $ 67,130 67,315 159,586 193,818

Retirement Plans (Table)

Retirement Plans (Table)	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Schedule of Components of Net Periodic Benefit Cost	Pension Plan Pension Plan Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Net Periodic Benefit Cost: Interest cost $ 3,095 3,111 9,285 9,332 Expected return on plan assets (5,681 ) (4,854 ) (17,044 ) (14,563 ) Amortization of unrecognized net actuarial loss 494 481 1,481 1,444 Total net periodic benefit cost 1 $ (2,092 ) (1,262 ) (6,278 ) (3,787 ) 1 The components of net periodic benefit cost are included within "Loss and loss expense incurred" and "Other insurance expenses" on the Consolidated Statements of Income.
Schedule of Weighted-Average Expense Assumptions	Pension Plan Nine Months ended September 30, 2018 2017 Weighted-Average Expense Assumptions: Discount rate 3.78 % 4.41 % Effective interest rate for calculation of interest cost 3.46 3.83 Expected return on plan assets 6.36 6.24

Comprehensive Income (Tables)

Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2018
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Schedule of Components of Comprehensive Income-Gross and Net of Tax	Third Quarter 2018 ($ in thousands) Gross Tax Net Net income $ 67,130 11,695 55,435 Components of other comprehensive loss: Unrealized losses on investment securities : Unrealized holding losses during period (21,565 ) (4,529 ) (17,036 ) Amounts reclassified into net income: HTM securities (8 ) (2 ) (6 ) Realized losses on disposals of AFS securities 10,839 2,276 8,563 Total unrealized losses on investment securities (10,734 ) (2,255 ) (8,479 ) Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 532 112 420 Total defined benefit pension and post-retirement plans 532 112 420 Other comprehensive loss (10,202 ) (2,143 ) (8,059 ) Comprehensive income $ 56,928 9,552 47,376 Third Quarter 2017 ($ in thousands) Gross Tax Net Net income $ 67,315 20,597 46,718 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 16,729 5,855 10,874 Non-credit portion of OTTI recognized in OCI 30 11 19 Amounts reclassified into net income: HTM securities (54 ) (19 ) (35 ) Non-credit OTTI 38 13 25 Realized gains on disposals of AFS securities (6,760 ) (2,366 ) (4,394 ) Total unrealized gains on investment securities 9,983 3,494 6,489 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 507 178 329 Total defined benefit pension and post-retirement plans 507 178 329 Other comprehensive income 10,490 3,672 6,818 Comprehensive income $ 77,805 24,269 53,536 Nine Months 2018 ($ in thousands) Gross Tax Net Net income $ 159,586 26,407 133,179 Components of other comprehensive loss: Unrealized losses on investment securities : Unrealized holding losses during period (130,873 ) (27,484 ) (103,389 ) Amounts reclassified into net income: HTM securities (28 ) (6 ) (22 ) Realized losses on disposals of AFS securities 18,258 3,834 14,424 Total unrealized losses on investment securities (112,643 ) (23,656 ) (88,987 ) Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,595 335 1,260 Total defined benefit pension and post-retirement plans 1,595 335 1,260 Other comprehensive loss (111,048 ) (23,321 ) (87,727 ) Comprehensive income $ 48,538 3,086 45,452 Nine Months 2017 ($ in thousands) Gross Tax Net Net income $ 193,818 55,234 138,584 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 78,401 27,440 50,961 Non-credit portion of OTTI recognized in OCI 36 13 23 Amounts reclassified into net income: HTM securities (146 ) (51 ) (95 ) Non-credit OTTI 38 13 25 Realized gains on disposals of AFS securities (7,135 ) (2,497 ) (4,638 ) Total unrealized gains on investment securities 71,194 24,918 46,276 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,522 533 989 Total defined benefit pension and post-retirement plans 1,522 533 989 Other comprehensive income 72,716 25,451 47,265 Comprehensive income $ 266,534 80,685 185,849
Schedule of Components of Accumulated Other Comprehensive Income Net of Tax	September 30, 2018 Defined Benefit Pension and Post-Retirement Plans Net Unrealized Gains (Losses) on Investment Securities Total AOCI ($ in thousands) OTTI Related HTM Related All Other Investments Subtotal Balance, December 31, 2017 $ (59 ) (14 ) 80,648 80,575 (60,405 ) 20,170 Cumulative effect adjustments (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 — — (103,389 ) (103,389 ) — (103,389 ) Amounts reclassified from AOCI — (22 ) 14,424 14,402 1,260 15,662 Net current period OCI — (22 ) (88,965 ) (88,987 ) 1,260 (87,727 ) Balance, September 30, 2018 $ (71 ) (38 ) (21,109 ) (21,218 ) (71,358 ) (92,576 )
Schedule of Reclassifications Out Of Accumulated Other Comprehensive Income	Quarter ended September 30, Nine Months ended September 30, Affected Line Item in the Unaudited Consolidated Statements of Income ($ in thousands) 2018 2017 2018 2017 OTTI related Non-credit OTTI on disposed securities $ — 38 — 38 Net realized and unrealized (losses) gains — 38 — 38 Income before federal income tax — (13 ) — (13 ) Total federal income tax expense — 25 — 25 Net income HTM related Unrealized losses on HTM disposals $ 11 11 5 41 Net realized and unrealized (losses) gains Amortization of net unrealized gains on HTM securities (19 ) (65 ) (33 ) (187 ) Net investment income earned (8 ) (54 ) (28 ) (146 ) Income before federal income tax 2 19 6 51 Total federal income tax expense (6 ) (35 ) (22 ) (95 ) Net income Realized losses (gains) on AFS and OTTI Realized losses (gains) on AFS disposals and OTTI 10,839 (6,760 ) 18,258 (7,135 ) Net realized and unrealized (losses) gains 10,839 (6,760 ) 18,258 (7,135 ) Income before federal income tax (2,276 ) 2,366 (3,834 ) 2,497 Total federal income tax expense 8,563 (4,394 ) 14,424 (4,638 ) Net income Defined benefit pension and post-retirement life plans Net actuarial loss 112 110 337 331 Loss and loss expense incurred 420 397 1,258 1,191 Other insurance expenses Total defined benefit pension and post-retirement life 532 507 1,595 1,522 Income before federal income tax (112 ) (178 ) (335 ) (533 ) Total federal income tax expense 420 329 1,260 989 Net income Total reclassifications for the period $ 8,977 (4,075 ) 15,662 (3,719 ) Net income

Federal Income Taxes (Tables)

Federal Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2018 2017 2018 2017 Statutory tax rate 21 % 35 21 35 Tax at statutory rate $ 14,097 23,560 33,513 67,836 Tax-advantaged interest (1,338 ) (2,915 ) (4,242 ) (8,479 ) Dividends received deduction (107 ) (382 ) (443 ) (1,338 ) Stock-based compensation (415 ) (86 ) (2,963 ) (3,409 ) Other (542 ) 420 542 624 Federal income tax expense $ 11,695 20,597 26,407 55,234

Accounting Pronouncements (Deta

Accounting Pronouncements (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Undistributed gains of equity method investments	$ (4,243)	$ (4,247)
Distributions in excess of current year income of equity method investments	3,210	552
Decrease (increase) in other assets	(13,881)	(6,304)
Net cash provided by operating activities	292,485	290,318
Distributions from other investments	23,420	17,041
Net cash used in investing activities	(287,356)	(277,621)
AOCI Attributable to Parent [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption	(25,019)
AOCI Attributable to Parent [Member] | Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption	(30,726)	0
AOCI Attributable to Parent [Member] | Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption	$ 5,707	0
Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Undistributed gains of equity method investments		(5,157)
Distributions in excess of current year income of equity method investments		0
Decrease (increase) in other assets		12,678
Net cash provided by operating activities		307,838
Distributions from other investments		18,503
Net cash used in investing activities		$ (276,159)

Statements of Cash Flow (Cash F

Statements of Cash Flow (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Interest	$ 15,449	$ 15,356
Federal income tax	7,193	39,000
Assets acquired under capital lease arrangements	4,114	278
Cash	446		$ 534
Restricted cash	12,386		44,176
Total cash and restricted cash shown in the Statements of Cash Flows	12,832	18,659	$ 44,710	$ 37,405
AFS Fixed Income Securities [Member]
Corporate actions related to securities	32,757	6,192
Equity Securities [Member]
Corporate actions related to securities	$ 944	$ 4,725

Investments (Held-To-Maturity S

Investments (Held-To-Maturity Securities Disclosure) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 44,632	$ 42,150
Net Unrealized Gains (Losses)	(50)	(21)
HTM, Carrying Value	44,582	42,129
Unrecognized Holding Gains	1,658	2,026
Unrecognized Holding Losses	0	(55)
Held-to-maturity securities, fair value	46,240	44,100
Obligations of States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	21,834	25,154
Net Unrealized Gains (Losses)	36	84
HTM, Carrying Value	21,870	25,238
Unrecognized Holding Gains	526	1,023
Unrecognized Holding Losses	0	0
Held-to-maturity securities, fair value	22,396	26,261
Corporate Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	22,798	16,996
Net Unrealized Gains (Losses)	(86)	(105)
HTM, Carrying Value	22,712	16,891
Unrecognized Holding Gains	1,132	1,003
Unrecognized Holding Losses	0	(55)
Held-to-maturity securities, fair value	$ 23,844	$ 17,839

Investments (Available-For-Sale

Investments (Available-For-Sale Securities Disclosure) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	$ 5,216,964	$ 5,220,527
Unrealized Gains	25,153	130,058
Unrealized Losses	(51,961)	(5,358)
AFS securities, fair value	5,190,156	5,345,227
AFS Fixed Income Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost		5,076,716
Unrealized Gains		90,867
Unrealized Losses		(5,061)
AFS securities, fair value		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	97,304	49,326
Unrealized Gains	306	647
Unrealized Losses	(1,148)	(233)
AFS securities, fair value	96,462	49,740
AFS Fixed Income Securities [Member] | Foreign Government [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	18,015	18,040
Unrealized Gains	88	526
Unrealized Losses	(120)	(11)
AFS securities, fair value	17,983	18,555
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	1,161,322	1,539,307
Unrealized Gains	10,848	44,245
Unrealized Losses	(7,261)	(582)
AFS securities, fair value	1,164,909	1,582,970
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	1,662,613	1,588,339
Unrealized Gains	6,342	30,891
Unrealized Losses	(19,302)	(1,762)
AFS securities, fair value	1,649,653	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	772,738	789,152
Unrealized Gains	4,571	6,508
Unrealized Losses	(2,540)	(202)
AFS securities, fair value	774,769	795,458
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	495,208	382,727
Unrealized Gains	328	1,563
Unrealized Losses	(5,987)	(841)
AFS securities, fair value	489,549	383,449
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost	1,009,764	709,825
Unrealized Gains	2,670	6,487
Unrealized Losses	(15,603)	(1,430)
AFS securities, fair value	$ 996,831	714,882
Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost		143,811
Unrealized Gains		39,191
Unrealized Losses		(297)
AFS securities, fair value		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)
AFS securities, fair value		167,757
Equity Securities [Member] | Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Cost/Amortized Cost		14,115
Unrealized Gains		904
Unrealized Losses		(71)
AFS securities, fair value		$ 14,948

Investments (Fair Value and Gro

Investments (Fair Value and Gross Pre-Tax Net Unrealized Unrecognized Loss of Securities By Length of Time) (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Percent Of Securities of Amortized Cost In An Unrealized Unrecognized Loss Position		2.00%	1.00%
AFS Fair Value, Less than 12 months		$ 3,159,528	$ 878,126
AFS Unrealized Losses, Less than 12 months	[1]	(50,169)	(4,961)
AFS Fair Value, 12 months or longer		47,125	35,686
AFS Unrealized Losses, 12 months or longer	[1]	(1,792)	(397)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		3,206,653	913,812
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(51,961)	(5,358)
Held-to-maturity Securities [Member]
Unrealized Unrecognized Loss		200	100
AFS Fixed Income Securities [Member]
AFS Fair Value, Less than 12 months			869,566
AFS Unrealized Losses, Less than 12 months	[1]		(4,664)
AFS Fair Value, 12 months or longer			35,686
AFS Unrealized Losses, 12 months or longer	[1]		(397)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value			905,252
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]		(5,061)
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member]
AFS Fair Value, Less than 12 months		26,414	23,516
AFS Unrealized Losses, Less than 12 months	[1]	(843)	(233)
AFS Fair Value, 12 months or longer		8,497	250
AFS Unrealized Losses, 12 months or longer	[1]	(305)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		34,911	23,766
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(1,148)	(233)
AFS Fixed Income Securities [Member] | Foreign Government [Member]
AFS Fair Value, Less than 12 months		7,281	1,481
AFS Unrealized Losses, Less than 12 months	[1]	(120)	(11)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		7,281	1,481
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(120)	(11)
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
AFS Fair Value, Less than 12 months		411,980	107,514
AFS Unrealized Losses, Less than 12 months	[1]	(7,008)	(422)
AFS Fair Value, 12 months or longer		6,397	14,139
AFS Unrealized Losses, 12 months or longer	[1]	(253)	(160)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		418,377	121,653
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(7,261)	(582)
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
AFS Fair Value, Less than 12 months		1,140,349	238,326
AFS Unrealized Losses, Less than 12 months	[1]	(19,052)	(1,744)
AFS Fair Value, 12 months or longer		6,373	3,228
AFS Unrealized Losses, 12 months or longer	[1]	(250)	(18)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		1,146,722	241,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(19,302)	(1,762)
AFS Fixed Income Securities [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member]
AFS Fair Value, Less than 12 months		497,809	74,977
AFS Unrealized Losses, Less than 12 months	[1]	(2,479)	(196)
AFS Fair Value, 12 months or longer		4,335	1,655
AFS Unrealized Losses, 12 months or longer	[1]	(61)	(6)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		502,144	76,632
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(2,540)	(202)
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
AFS Fair Value, Less than 12 months		376,359	154,267
AFS Unrealized Losses, Less than 12 months	[1]	(5,940)	(773)
AFS Fair Value, 12 months or longer		2,340	5,214
AFS Unrealized Losses, 12 months or longer	[1]	(47)	(68)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		378,699	159,481
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(5,987)	(841)
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
AFS Fair Value, Less than 12 months		699,336	269,485
AFS Unrealized Losses, Less than 12 months	[1]	(14,727)	(1,285)
AFS Fair Value, 12 months or longer		19,183	11,200
AFS Unrealized Losses, 12 months or longer	[1]	(876)	(145)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		718,519	280,685
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	$ (15,603)	(1,430)
Equity Securities [Member]
AFS Fair Value, Less than 12 months			8,560
AFS Unrealized Losses, Less than 12 months	[1]		(297)
AFS Fair Value, 12 months or longer			0
AFS Unrealized Losses, 12 months or longer	[1]		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value			8,560
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]		(297)
Equity Securities [Member] | Common Stock [Member]
AFS Fair Value, Less than 12 months			4,727
AFS Unrealized Losses, Less than 12 months	[1]		(226)
AFS Fair Value, 12 months or longer			0
AFS Unrealized Losses, 12 months or longer	[1]		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value			4,727
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]		(226)
Equity Securities [Member] | Preferred Stock [Member]
AFS Fair Value, Less than 12 months			3,833
AFS Unrealized Losses, Less than 12 months	[1]		(71)
AFS Fair Value, 12 months or longer			0
AFS Unrealized Losses, 12 months or longer	[1]		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value			3,833
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]		$ (71)
[1]	Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI.

Investments (Fixed Income Secur

Investments (Fixed Income Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Fixed Income Securities [Line Items]
Due in one year or less fair value, AFS	$ 176,545
Due after one year through five years fair value, AFS	2,107,663
Due after five years through 10 years fair value, AFS	2,759,167
Due after 10 years fair value, AFS	146,781
AFS, Fair Value	5,190,156	$ 5,162,522
Due in one year or less carrying value, HTM	14,017
Due after one year through five years carrying value, HTM	20,518
Due after five years through 10 years carrying value, HTM	10,047
Due after 10 years carrying value, HTM	0
HTM, Carrying Value	44,582	42,129
Due in one year or less fair value, HTM	14,150
Due after one year through five years fair value, HTM	21,926
Due after five years through 10 years fair value, HTM	10,164
Due after 10 years fair value, HTM	0
HTM, Fair Value	$ 46,240	$ 44,100

Investments (Other Investment P

Investments (Other Investment Portfolio by Strategy and the Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy) (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Carrying Value		$ 163,930	$ 132,268
Other Investments [Member]
Carrying Value		163,930	132,268
Remaining Commitment		218,181	220,999
Maximum Exposure to Loss	[1]	382,111	353,267
Alternative Investments [Member]
Carrying Value		138,247	115,373
Remaining Commitment		218,181	220,999
Maximum Exposure to Loss	[1]	356,428	336,372
Private Equity [Member] | Alternative Investments [Member]
Carrying Value		75,508	52,251
Remaining Commitment		99,346	99,026
Maximum Exposure to Loss	[1]	174,854	151,277
Private Credit [Member] | Alternative Investments [Member]
Carrying Value		37,525	37,743
Remaining Commitment		85,747	94,959
Maximum Exposure to Loss	[1]	123,272	132,702
Real Assets [Member] | Alternative Investments [Member]
Carrying Value		25,214	25,379
Remaining Commitment		33,088	27,014
Maximum Exposure to Loss	[1]	58,302	52,393
Other Securities [Member]
Carrying Value		25,683	16,895
Remaining Commitment		0	0
Maximum Exposure to Loss	[1]	$ 25,683	$ 16,895
[1]	The maximum exposure to loss includes both the carry 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.

Investments (Aggregated Income

Investments (Aggregated Income Statement Summarized Financial Information for Partnerhips in our Alternative Investment Portfolio) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Net investment income earned	$ 52,443	$ 40,446	$ 141,227	$ 119,295
Alternative Investments [Member]
Schedule of Equity Method Investments [Line Items]
Net investment income earned	7,100	2,700	10,600	9,500
Investments accounted for under the equity method [Member]
Schedule of Equity Method Investments [Line Items]
Net investment income (loss)	11,900	600	(29,900)	(61,800)
Realized gains (losses)	124,800	43,300	1,348,300	(261,000)
Net change in unrealized appreciation	1,434,300	1,296,300	695,800	3,186,300
Net gain	$ 1,571,000	$ 1,340,200	$ 2,014,200	$ 2,863,500

Investments (Investments Pledge

Investments (Investments Pledged as Collateral) (Details) $ in Millions	Sep. 30, 2018USD ($)
Financial Instruments Owned and Pledged as Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	$ 26
Securities Pledged As Collateral	176.7
U.S. Government and Government Agencies [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	22.2
Securities Pledged As Collateral	22.2
Obligations of States and Political Subdivisions [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	3.8
Securities Pledged As Collateral	3.8
Commercial Mortgage Backed Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	0
Securities Pledged As Collateral	16.6
Residential Mortgage Backed Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	0
Securities Pledged As Collateral	134.1
Federal Home Loan Bank of Indianapolis [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	65
Federal Home Loan Bank of Indianapolis [Member] | U.S. Government and Government Agencies [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	0
Federal Home Loan Bank of Indianapolis [Member] | Obligations of States and Political Subdivisions [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	0
Federal Home Loan Bank of Indianapolis [Member] | Commercial Mortgage Backed Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	7.2
Federal Home Loan Bank of Indianapolis [Member] | Residential Mortgage Backed Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	57.8
Federal Home Loan Bank of New York [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	85.7
Federal Home Loan Bank of New York [Member] | U.S. Government and Government Agencies [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	0
Federal Home Loan Bank of New York [Member] | Obligations of States and Political Subdivisions [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	0
Federal Home Loan Bank of New York [Member] | Commercial Mortgage Backed Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	9.4
Federal Home Loan Bank of New York [Member] | Residential Mortgage Backed Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	$ 76.3

Investments (Credit Concentrati

Investments (Credit Concentration Risk) (Details)	Sep. 30, 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-backed investments	10.00%	10.00%

Investments (Net Investment Inc

Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net Investment Income [Line Items]
Net investment income earned	$ 52,443	$ 40,446	$ 141,227	$ 119,295
Fixed Income Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	45,088	38,865	130,903	113,424
Equity Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	2,079	1,605	5,876	4,492
Short-Term Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	867	396	2,001	1,023
Other Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	7,211	2,659	10,868	9,493
Investment Expenses [Member]
Net Investment Income [Line Items]
Net investment income earned	$ (2,802)	$ (3,079)	$ (8,421)	$ (9,137)

Investments (OTTI) (Details)

Investments (OTTI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Investments [Abstract]
OTTI Charges	$ 1,426	$ 73	$ 5,459	$ 4,765

Investments (Components Of Net

Investments (Components Of Net Realized and Unrealized Gains and Losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Gain (Loss) on Securities [Line Items]
Net realized (losses) gains on disposals of securities, fixed income securities (excluding OTTI charges)		$ (9,413)	$ 1,996	$ (13,922)	$ 6,566
Total net realized gains on the disposal of securities (excluding OTTI charges)		(751)	6,871	4,034	12,252
OTTI Charges		(1,426)	(73)	(5,459)	(4,765)
Net realized (losses) gains		(2,177)	6,798	(1,425)	7,487
Unrealized (losses) recognized in income on equity securities	[1]	(2,610)	0	(15,563)	0
Total net realized and unrealized (losses) gains		(4,787)	6,798	(16,988)	7,487
Unrealized holding gains (losses) on equity securities		5,500		4,200
Unrealized losses on equity securities sold during the period		(8,100)		(19,800)
Equity Securities [Member]
Gain (Loss) on Securities [Line Items]
Total net realized gains on the disposal of securities (excluding OTTI charges)		8,665	4,875	17,960	5,225
Short-Term Investments [Member]
Gain (Loss) on Securities [Line Items]
Total net realized gains on the disposal of securities (excluding OTTI charges)		2	0	1	0
Other Investments [Member]
Gain (Loss) on Securities [Line Items]
Total net realized gains on the disposal of securities (excluding OTTI charges)		$ (5)	$ 0	$ (5)	$ 461
[1]	Includes unrealized holding gains (losses) of: (i) $5.5 million in Third Quarter 2018 and $4.2 million in Nine Months 2018 on equity securities remaining in our portfolio as of September 30, 2018; and (ii) $(8.1) million in Third Quarter 2018 and $(19.8) million in Nine Months 2018 on equity securities sold during the respective periods.

Investments (Net Realized Gains

Investments (Net Realized Gains (Losses) on Disposals) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Realized Gains (Losses) on Disposals Excluding OTTI [Line Items]
HTM fixed income securities Gains	$ 0	$ 0	$ 2	$ 44
HTM fixed income securities Losses	0	0	0	(1)
Equity securities Gains	10,584		20,209
Equity securities Losses	(1,919)		(2,249)
Short-term investments Gains	3	0	6	2
Short-term investments Losses	(1)	0	(5)	(2)
Other investments Gains	0	0	0	480
Other investments Losses	(5)	0	(5)	(19)
Net realized investment (losses) gains on disposals	(751)	6,871	4,034	12,252
Sale of fixed income securities, available-for-sale	444,400	94,900	1,382,677	811,991
Sale of equity securities	36,100		79,676
Sale of equity securities, available-for-sale		12,700		19,007
Fixed Maturities [Member]
Schedule of Realized Gains (Losses) on Disposals Excluding OTTI [Line Items]
AFS securities Gains	462	2,070	5,056	8,337
AFS securities Losses	(9,875)	(74)	(18,980)	(1,814)
Equity Securities [Member]
Schedule of Realized Gains (Losses) on Disposals Excluding OTTI [Line Items]
AFS securities Gains		4,875		5,225
AFS securities Losses		0		0
Net realized investment (losses) gains on disposals	$ 8,665	$ 4,875	$ 17,960	$ 5,225

Indebtedness Indebtedness (Deta

Indebtedness Indebtedness (Details) $ in Millions	Sep. 30, 2018USD ($)
One Point Seventy Five Percent Borrowing From Federal Home Loan Bank Due March 20, 2018 [Member]
Short-term Debt [Line Items]
Federal Home Loan Bank Advances	$ 75
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]
Short-term Debt [Line Items]
Federal Home Loan Bank Advances	$ 55
Federal Home Loan Bank, Advances, Interest Rate	1.98%

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Disclosures of Fair Value Assets) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Percentage increase in long-term debt		1.00%
Available-for-sale Securities, Fixed Income Securities		$ 5,190,156	$ 5,162,522
Equity securities, available-for-sale			182,705
Total AFS securities		5,190,156	5,345,227
Short-term investments		304,572	165,555
Net Asset Value		30,400	23,700
Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		5,190,156	5,162,522
Equity securities, available-for-sale			182,705
Equity securities		157,867
Total AFS securities			5,345,227
Short-term investments		304,572	165,555
Total assets measured at fair value		5,652,595	5,510,782
U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		96,462	49,740
Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		17,983	18,555
Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		1,164,909	1,582,970
Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		1,649,653	1,617,468
Collateralized Loan Obligations and Other Asset Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		774,769	795,458
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		489,549	383,449
Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		996,831	714,882
Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, available-for-sale	[1]		167,757
Equity securities	[1]	154,845
Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, available-for-sale			14,948
Equity securities		3,022
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	76,760	24,652
Equity securities, available-for-sale	[2]		153,588
Equity securities	[2]	127,467
Total AFS securities	[2]		178,240
Short-term investments	[2]	303,572	165,555
Total assets measured at fair value	[2]	507,799	343,795
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	76,760	24,652
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	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]
Available-for-sale Securities, Fixed Income Securities	[2]	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	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]
Available-for-sale Securities, Fixed Income Securities	[2]	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, available-for-sale	[1],[2]		138,640
Equity securities	[1],[2]	124,445
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, available-for-sale	[2]		14,948
Equity securities	[2]	3,022
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	5,109,255	5,131,316
Equity securities, available-for-sale	[2]		0
Equity securities	[2]	0
Total AFS securities	[2]		5,131,316
Short-term investments	[2]	1,000	0
Total assets measured at fair value	[2]	5,110,255	5,131,316
Significant Other Observable Inputs (Level 2) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	19,702	25,088
Significant Other Observable Inputs (Level 2) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	17,983	18,555
Significant Other Observable Inputs (Level 2) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	1,164,909	1,582,970
Significant Other Observable Inputs (Level 2) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	1,649,653	1,617,468
Significant Other Observable Inputs (Level 2) [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	770,628	795,458
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	489,549	376,895
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities	[2]	996,831	714,882
Significant Other Observable Inputs (Level 2) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, available-for-sale	[1],[2]		0
Equity securities	[1],[2]	0
Significant Other Observable Inputs (Level 2) [Member] | Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, available-for-sale	[2]		0
Equity securities	[2]	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		4,141	6,554
Equity securities, available-for-sale			5,398
Equity securities		0
Total AFS securities			11,952
Short-term investments		0	0
Total assets measured at fair value		4,141	11,952
Significant Unobservable Inputs (Level 3) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		4,141	0
Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		0	6,554
Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Fixed Income Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, available-for-sale	[1]		5,398
Equity securities	[1]	0
Significant Unobservable Inputs (Level 3) [Member] | Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, available-for-sale			$ 0
Equity securities		$ 0
[1]	Investments amounting to $30.4 million at September 30, 2018, and $23.7 million at December 31, 2017, were measured at fair value using 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.
[2]	There were no transfers of securities between Level 1 and Level 2.

Fair Value Measurements (Change

Fair Value Measurements (Change in Fair Value of Securities Using Level 3 Inputs) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Commercial Mortgage Backed Securities [Member] | AFS Fixed Maturity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, December 31, 2017	$ 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, September 30, 2018	0
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
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, September 30, 2018	0
Equity Securities [Member] | Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, December 31, 2017	5,398
Collateralized Loan Obligations and Other Asset Backed Securities [Member] | Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, December 31, 2017	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	4,141
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	0
Fair value, September 30, 2018	$ 4,141

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	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	$ 46,240	$ 44,100
Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	57,733	61,391
Six Point Seventy Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	106,760	116,597
Five Point Eight Hundred Seventy Five Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	184,778	186,332
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	23,936	24,270
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	23,871	24,210
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	57,795	60,334
Long-term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	454,873	473,134
Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	22,396	26,261
Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	23,844	17,839
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	0	0
Long-term debt, fair value	184,778	186,332
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Six Point Seventy Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Five Point Eight Hundred Seventy Five Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	184,778	186,332
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	33,979	38,567
Long-term debt, fair value	270,095	286,802
Significant Other Observable Inputs (Level 2) [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	57,733	61,391
Significant Other Observable Inputs (Level 2) [Member] | Six Point Seventy Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	106,760	116,597
Significant Other Observable Inputs (Level 2) [Member] | Five Point Eight Hundred Seventy Five Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Significant Other Observable Inputs (Level 2) [Member] | One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	23,936	24,270
Significant Other Observable Inputs (Level 2) [Member] | One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	23,871	24,210
Significant Other Observable Inputs (Level 2) [Member] | Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	57,795	60,334
Significant Other Observable Inputs (Level 2) [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	22,396	26,261
Significant Other Observable Inputs (Level 2) [Member] | Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	11,583	12,306
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	12,261	5,533
Long-term debt, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Six Point Seventy Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Five Point Eight Hundred Seventy Five Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities, fair value	$ 12,261	$ 5,533

Reinsurance (List of Direct, As

Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Premiums written:
Direct	$ 752,834	$ 706,918	$ 2,220,431	$ 2,097,146
Assumed	7,084	8,506	19,891	20,685
Ceded	(108,250)	(111,147)	(308,846)	(301,036)
Net	651,668	604,277	1,931,476	1,816,795
Premiums earned:
Direct	706,497	666,048	2,086,953	1,967,364
Assumed	6,484	7,623	19,220	19,465
Ceded	(98,704)	(101,616)	(295,232)	(285,890)
Net	614,277	572,055	1,810,941	1,700,939
Loss and loss expenses incurred:
Direct	477,427	455,728	1,289,357	1,187,400
Assumed	6,529	5,420	16,897	17,623
Ceded	(104,757)	(116,561)	(175,786)	(201,405)
Net	379,199	344,587	1,130,468	1,003,618
National Flood Insurance Program [Member]
Premiums written:
Ceded	(70,100)	(68,132)	(193,110)	(188,274)
Premiums earned:
Ceded	(61,448)	(59,847)	(180,582)	(174,779)
Loss and loss expenses incurred:
Ceded	$ (89,396)	$ (112,994)	$ (115,376)	$ (134,675)

Reinsurance (Ceded Premiums and

Reinsurance (Ceded Premiums and Losses Related to Flood Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Ceded premiums written	$ (108,250)	$ (111,147)	$ (308,846)	$ (301,036)
Ceded premiums earned	(98,704)	(101,616)	(295,232)	(285,890)
Ceded loss and loss expenses incurred	(104,757)	(116,561)	(175,786)	(201,405)
National Flood Insurance Program [Member]
Ceded premiums written	(70,100)	(68,132)	(193,110)	(188,274)
Ceded premiums earned	(61,448)	(59,847)	(180,582)	(174,779)
Ceded loss and loss expenses incurred	$ (89,396)	$ (112,994)	$ (115,376)	$ (134,675)
Percentage of NFIP claims ceded by federal government			100.00%

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	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Increase in current year loss and loss expense incurred	$ 111,000
Increase in non catastrophe property losses	61,900
Non catastrophe property losses	278,500
Gross reserve for loss and loss expense, at beginning of year	3,771,240	$ 3,691,719
Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of year	585,855	611,200
Net reserve for loss and loss expense, at beginning of year	3,185,385	3,080,519
Incurred loss and loss expense for claims occurring in the current year	1,148,032	1,037,079
Total incurred loss and loss expense	1,130,468	1,003,618
Paid loss and loss expense for claims occurring in the current year	369,036	314,686
Paid loss and loss expense for claims occurring in the prior years	610,734	581,186
Total paid loss and loss expense	979,770	895,872
Net reserve for loss and loss expense, at end of period	3,336,083	3,188,265
Add: reinsurance recoverable on unpaid loss and loss expense, at end of period	589,072	647,535
Gross reserve for loss and loss expense, at end of period	3,925,155	3,835,800
Change in Historical Claim Rate Experience [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	(17,564)	(33,461)
Property Insurance Product Line [Member] | Change in Historical Claim Rate Experience [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	6,400
Casualty Insurance Product Line [Member] | Change in Historical Claim Rate Experience [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	(24,000)
General Liability [Member] | Casualty Insurance Product Line [Member] | Change in Historical Claim Rate Experience [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	(8,000)	(48,300)
Excess And Surplus Operations [Member] | Casualty Insurance Product Line [Member] | Change in Historical Claim Rate Experience [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	12,000	10,000
Personal Automobile [Member] | Casualty Insurance Product Line [Member] | Change in Historical Claim Rate Experience [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development		4,000
Commercial Automobile [Member] | Casualty Insurance Product Line [Member] | Change in Historical Claim Rate Experience [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	25,000	26,000
Workers Compensation [Member] | Casualty Insurance Product Line [Member] | Change in Historical Claim Rate Experience [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ (53,000)	$ (29,300)

Segment Information Narrative (

Segment Information Narrative (Details)	9 Months Ended
	Sep. 30, 2018
Number of Operating Segments	4

Segment Information (Revenue by

Segment Information (Revenue by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total net premiums earned	$ 614,277	$ 572,055	$ 1,810,941	$ 1,700,939
Other income	2,538	1,994	7,896	8,526
Net investment income	52,443	40,446	141,227	119,295
Net realized and unrealized investment (losses) gains	(4,787)	6,798	(16,988)	7,487
Total investment revenues	47,656	47,244	124,239	126,782
Total revenues	664,471	621,293	1,943,076	1,836,247
Standard Commercial Lines [Member]
Segment Reporting Information [Line Items]
Other income	2,228	1,712	6,936	7,588
Total revenues	483,284	446,962	1,429,368	1,334,846
Standard Commercial Lines [Member] | Commercial Automobile [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	124,862	111,711	365,197	327,156
Standard Commercial Lines [Member] | Workers Compensation [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	78,784	77,580	237,628	236,366
Standard Commercial Lines [Member] | General Liability [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	154,974	141,059	457,805	422,546
Standard Commercial Lines [Member] | Commercial Property [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	83,056	78,151	245,544	232,594
Standard Commercial Lines [Member] | Business Owners' Policies [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	25,994	25,019	77,414	74,853
Standard Commercial Lines [Member] | Bonds Segment [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	8,778	7,420	25,247	20,904
Standard Commercial Lines [Member] | Other Commercial [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	4,608	4,310	13,597	12,839
Standard Personal Lines [Member]
Segment Reporting Information [Line Items]
Other income	310	282	959	938
Total revenues	77,467	72,883	228,049	216,412
Standard Personal Lines [Member] | Personal Automobile [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	42,772	38,612	125,024	113,225
Standard Personal Lines [Member] | Homeowners [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	32,293	32,215	96,717	97,382
Standard Personal Lines [Member] | Other Personal [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	2,092	1,774	5,349	4,867
Excess And Surplus Operations [Member]
Segment Reporting Information [Line Items]
Other income	0	0	1	0
Total revenues	56,064	54,204	161,420	158,207
Excess And Surplus Operations [Member] | Casualty Insurance Product Line [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	42,179	40,090	120,098	117,056
Excess And Surplus Operations [Member] | Property Insurance Product Line [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	$ 13,885	$ 14,114	$ 41,321	$ 41,151

Segment Information (Income Bef

Segment Information (Income Before and After Federal Income Tax) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Net investment income	$ 52,443	$ 40,446	$ 141,227	$ 119,295
Net realized and unrealized investment (losses) gains	(4,787)	6,798	(16,988)	7,487
Total investment income, before federal income tax	47,656	47,244	124,239	126,782
Tax on investment income	8,562	13,236	21,405	34,572
Total investment income, after federal income tax	39,094	34,008	102,834	92,210
Standard Commercial Lines [Member]
Segment Reporting Information [Line Items]
Underwriting gain (loss), before federal income tax	26,333	35,329	74,153	112,634
Underwriting gain (loss), after federal income tax	$ 20,803	$ 22,964	$ 58,581	$ 73,212
Combined ratio	94.50%	92.10%	94.80%	91.50%
Standard Personal Lines [Member]
Segment Reporting Information [Line Items]
Underwriting gain (loss), before federal income tax	$ 3,158	$ 8,179	$ 6,457	$ 7,517
Underwriting gain (loss), after federal income tax	$ 2,495	$ 5,316	$ 5,101	$ 4,886
Combined ratio	95.90%	88.70%	97.20%	96.50%
Excess And Surplus Operations [Member]
Segment Reporting Information [Line Items]
Underwriting gain (loss), before federal income tax	$ 3,506	$ (11,063)	$ (4,848)	$ (8,174)
Underwriting gain (loss), after federal income tax	$ 2,770	$ (7,191)	$ (3,830)	$ (5,313)
Combined ratio	93.70%	120.40%	103.00%	105.20%

Segment Information (Reconcilia

Segment Information (Reconciliation of Segment Results to Income Before Federal Income Tax (Details)) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Investment income, before federal income tax	$ 47,656	$ 47,244	$ 124,239	$ 126,782
Interest expense	(6,073)	(6,085)	(18,350)	(18,272)
Corporate expenses	(7,450)	(6,289)	(22,065)	(26,669)
Income before federal income tax	67,130	67,315	159,586	193,818
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	26,333	35,329	74,153	112,634
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	3,158	8,179	6,457	7,517
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	3,506	(11,063)	(4,848)	(8,174)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total underwriting gain (loss), before federal income tax all segments	$ 80,653	$ 79,689	$ 200,001	$ 238,759

Retirement Plans (Components of

Retirement Plans (Components of Net Periodic Benefit Cost) (Details) - Pension Plan [Member] - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost		$ 3,095	$ 3,111	$ 9,285	$ 9,332
Expected return on plan assets		(5,681)	(4,854)	(17,044)	(14,563)
Amortization of unrecognized net actuarial loss		494	481	1,481	1,444
Total net periodic benefit	[1]	$ (2,092)	$ (1,262)	$ (6,278)	$ (3,787)
[1]	The components of net periodic benefit cost are included within "Loss and loss expense incurred" and "Other insurance expenses" on the Consolidated Statements of Income.

Retirement Plans (Weighted-Aver

Retirement Plans (Weighted-Average Expense Assumptions) (Details) - Pension Plan [Member]	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.78%	4.41%
Effective interest rate for calculation of interest cost	3.46%	3.83%
Expected return on plan assets	6.36%	6.24%

Comprehensive Income (Component

Comprehensive Income (Components of Comprehensive Income-Gross and Net of Tax) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income, Gross	$ 67,130	$ 67,315	$ 159,586	$ 193,818
Unrealized holding (losses) gains during the period, Gross	(21,565)	16,729	(130,873)	78,401
Non-credit portion of OTTI recognized in OCI, Gross		30		36
Amounts reclassified into net income: HTM securities, Gross	(8)	(54)	(28)	(146)
Amounts reclassified into net income: Non-credit OTTI, Gross		38		38
Amounts reclassified into net income: Realized losses (gains) on disposals of AFS securities, Gross	10,839	(6,760)	18,258	(7,135)
Total unrealized (losses) gains on investment securities, Gross	(10,734)	9,983	(112,643)	71,194
Amount reclassified into net income: Net actuarial loss, Gross	532	507	1,595	1,522
Total defined pension and other post-retirement benefit plans, Gross	532	507	1,595	1,522
Other comprehensive (loss) income, Gross	(10,202)	10,490	(111,048)	72,716
Comprehensive income before tax	56,928	77,805	48,538	266,534
Net income, Tax	11,695	20,597	26,407	55,234
Unrealized holding (losses) gains during the period, Tax	(4,529)	5,855	(27,484)	27,440
Non-credit portion of OTTI recognized in OCI, Tax		11		13
Amounts reclassified into net income: HTM securities, Tax	(2)	(19)	(6)	(51)
Amounts reclassified into net income: Non-credit OTTI, Tax		13		13
Amounts reclassified into net income: Realized losses (gains) on disposals of AFS securities, Tax	2,276	(2,366)	3,834	(2,497)
Total unrealized (losses) gains on investment securities, Tax	(2,255)	3,494	(23,656)	24,918
Amount reclassified into net income: Net actuarial loss, Tax	112	178	335	533
Total defined pension and other post-retirement benefit plans, Tax	112	178	335	533
Other comprehensive (loss) income, Tax	(2,143)	3,672	(23,321)	25,451
Comprehensive income, Tax	9,552	24,269	3,086	80,685
Net income	55,435	46,718	133,179	138,584
Unrealized holding (losses) gains arising during period	(17,036)	10,874	(103,389)	50,961
Non-credit portion of OTTI recognized in OCI		19		23
Amounts reclassified into net income: HTM Securities	(6)	(35)	(22)	(95)
Amounts reclassified into net income: Non-credit other than temporary impairments	0	25	0	25
Amounts reclassified into net income: Realized losses (gains) on disposals of available-for-sale securities	8,563	(4,394)	14,424	(4,638)
Total unrealized (losses) gains on investment securities	(8,479)	6,489	(88,987)	46,276
Amount reclassified into net income: Net actuarial loss	420	329	1,260	989
Total defined benefit pension and post-retirement plans	420	329	1,260	989
Other comprehensive (loss) income	(8,059)	6,818	(87,727)	47,265
Comprehensive income	$ 47,376	$ 53,536	$ 45,452	$ 185,849

Comprehensive Income (Compone_2

Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			$ 20,170
Amounts reclassified from AOCI, Non-credit OTTI	$ 0	$ 25	0	$ 25
Amounts reclassified from AOCI, HTM related	(6)	(35)	(22)	(95)
Amounts reclassified from AOCI, All Other	8,563	(4,394)	14,424	(4,638)
OCI before reclassifications, Defined Benefit Pension and Post Retirement Plans			0
Amount reclassified into net income: Net actuarial loss	420	329	1,260	989
Other comprehensive income	(8,059)	6,818	(87,727)	47,265
Other Comprehensive Income, Defined Benefit Pension and Post Retirement Plans, Adjustment, Net of Tax	420	$ 329	1,260	989
Ending Balance, September 30, 2018	(92,576)		(92,576)
Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			80,648
Cumulative effect adjustment	(12,792)		(12,792)
OCI before reclassifications			(103,389)
Other comprehensive income			(88,965)
Ending Balance, September 30, 2018	(21,109)		(21,109)
Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			80,575
Cumulative effect adjustment	(12,806)		(12,806)
OCI before reclassifications			(103,389)
Amounts reclassified from AOCI			14,402
Other comprehensive income			(88,987)
Ending Balance, September 30, 2018	(21,218)		(21,218)
Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			(59)
Cumulative effect adjustment	(12)		(12)
OCI before reclassifications			0
Other comprehensive income			0
Ending Balance, September 30, 2018	(71)		(71)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Held-to-maturity Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			(14)
Cumulative effect adjustment	(2)		(2)
OCI before reclassifications			0
Other comprehensive income			(22)
Ending Balance, September 30, 2018	(38)		(38)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			(60,405)
Cumulative effect adjustment	(12,213)		(12,213)
Amount reclassified into net income: Net actuarial loss			1,260
Ending Balance, September 30, 2018	(71,358)		(71,358)
Accumulated other comprehensive income (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			20,170
Cumulative effect adjustment	(25,019)		(25,019)
OCI before reclassifications			(103,389)
Amounts reclassified from AOCI			15,662
Other comprehensive income			(87,727)	$ 47,265
Ending Balance, September 30, 2018	$ (92,576)		(92,576)
Adjustments for New Accounting Pronouncement [Member] | Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			67,856
Adjustments for New Accounting Pronouncement [Member] | Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			67,769
Adjustments for New Accounting Pronouncement [Member] | Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			(71)
Adjustments for New Accounting Pronouncement [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member] | Held-to-maturity Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			(16)
Adjustments for New Accounting Pronouncement [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			(72,618)
Adjustments for New Accounting Pronouncement [Member] | Accumulated other comprehensive income (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2017			$ (4,849)

Comprehensive Income (Reclassif

Comprehensive Income (Reclassification out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Total net realized and unrealized (losses) gains	$ 4,787	$ (6,798)	$ 16,988	$ (7,487)
Net investment income	52,443	40,446	141,227	119,295
Loss and loss expense incurred	379,199	344,587	1,130,468	1,003,618
Other insurance expenses	80,108	78,874	244,342	243,799
Income before federal income tax	67,130	67,315	159,586	193,818
Total federal income tax expense	(11,695)	(20,597)	(26,407)	(55,234)
Net income	55,435	46,718	133,179	138,584
Reclassification out of AOCI
Net income	8,977	(4,075)	15,662	(3,719)
Pension Plan [Member] | Reclassification out of AOCI
Loss and loss expense incurred	112	110	337	331
Other insurance expenses	420	397	1,258	1,191
Income before federal income tax	532	507	1,595	1,522
Total federal income tax expense	(112)	(178)	(335)	(533)
Net income	420	329	1,260	989
Non Credit OTTI On Disposed Securities [Member] | Reclassification out of AOCI
Total net realized and unrealized (losses) gains	0	38	0	38
Income before federal income tax	0	38	0	38
Total federal income tax expense	0	(13)	0	(13)
Net income	0	25	0	25
Held-to-maturity Securities [Member] | Reclassification out of AOCI
Total net realized and unrealized (losses) gains	(11)	(11)	(5)	(41)
Net investment income	(19)	(65)	(33)	(187)
Income before federal income tax	(8)	(54)	(28)	(146)
Total federal income tax expense	2	19	6	51
Net income	(6)	(35)	(22)	(95)
Available-for-sale Securities [Member] | Reclassification out of AOCI
Total net realized and unrealized (losses) gains	(10,839)	6,760	(18,258)	7,135
Income before federal income tax	10,839	(6,760)	18,258	(7,135)
Total federal income tax expense	(2,276)	2,366	(3,834)	2,497
Net income	$ 8,563	$ (4,394)	$ 14,424	$ (4,638)

Federal Income Taxes (Schedule

Federal Income Taxes (Schedule of Effective Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Statutory corporate tax rate percentage	21.00%	35.00%	21.00%	35.00%
Tax at statutory rate	$ 14,097	$ 23,560	$ 33,513	$ 67,836
Tax advantaged interest	(1,338)	(2,915)	(4,242)	(8,479)
Dividend received deduction	(107)	(382)	(443)	(1,338)
Stock-based compensation	(415)	(86)	(2,963)	(3,409)
Other	(542)	420	542	624
Total federal income tax expense	$ 11,695	$ 20,597	$ 26,407	$ 55,234

Subsequent Events Subsequent _2

Subsequent Events Subsequent Events (Details) $ in Millions	1 Months Ended
	Oct. 26, 2018USD ($)
Subsequent Event [Member]
Subsequent Event [Line Items]
Loss from Catastrophes	$ 10