Selective Insurance (SIGI) 10-Q 27 Oct 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 15, 2016
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
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		57,856,321

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
ASSETS
Fixed income securities, held-to-maturity – at carrying value (fair value: $136,094 – 2016; $209,544 – 2015)	$ 130,472	$ 201,354
Fixed income securities, available-for-sale – at fair value (amortized cost: $4,682,267 – 2016; $4,352,514 – 2015)	4,832,532	4,408,203
Equity securities, available-for-sale – at fair value (cost: $122,981 – 2016; $193,816 – 2015)	147,304	207,051
Short-term investments (at cost which approximates fair value)	169,604	194,819
Other investments	88,512	77,842
Total investments (Note 4)	5,368,424	5,089,269
Cash	1,493	898
Interest and dividends due or accrued	39,901	38,501
Premiums receivable, net of allowance for uncollectible accounts of: $5,907 – 2016; $4,422 – 2015	711,589	615,164
Reinsurance recoverables, net of allowance for uncollectible accounts of: $5,500 – 2016; $5,700 – 2015	640,012	561,968
Prepaid reinsurance premiums	151,981	140,889
Deferred federal income tax	41,656	92,696
Property and equipment – at cost, net of accumulated depreciation and amortization of: $198,171 – 2016; $188,548 – 2015	69,812	65,701
Deferred policy acquisition costs	235,934	213,159
Goodwill	7,849	7,849
Other assets	94,582	78,339
Total assets	7,363,233	6,904,433
Liabilities And Stockholders' Equity
Reserve for loss and loss expenses	3,686,586	3,517,728
Unearned premiums	1,306,255	1,169,710
Short-term debt	45,000	60,000
Long-term debt	378,551	328,192
Current federal income tax	6,509	7,442
Accrued salaries and benefits	103,583	167,336
Other liabilities	261,845	255,984
Total liabilities	5,788,329	5,506,392
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: 101,505,201 – 2016; 100,861,372 – 2015	203,011	201,723
Additional paid-in capital	342,846	326,656
Retained earnings	1,538,928	1,446,192
Accumulated other comprehensive income (loss) (Note 10)	62,209	(9,425)
Treasury stock - at cost (shares: 43,653,034 – 2016; 43,500,642 – 2015)	(572,090)	(567,105)
Total stockholders' equity	1,574,904	1,398,041
Commitments and contingencies
Total liabilities and stockholders' equity	$ 7,363,233	$ 6,904,433

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fixed income securities, held-to-maturity, fair value	$ 136,094	$ 209,544
Fixed income securities, available-for-sale, amortized cost	4,682,267	4,352,514
Equity securities, available-for-sale, cost	122,981	193,816
Premiums receivable, allowance for uncollectible accounts	5,907	4,422
Reinsurance recoverables, allowance for uncollectible accounts	5,500	5,700
Property and equipment - at cost, accumulated depreciation and amortization	$ 198,171	$ 188,548
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	101,505,201	100,861,372
Treasury stock - at cost, shares	43,653,034	43,500,642

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues:
Net premiums earned	$ 542,429	$ 507,390	$ 1,596,819	$ 1,473,822
Net investment income earned	33,375	32,061	95,326	91,208
Net realized gains:
Net realized investment gains	4,030	1,590	7,233	23,598
Other-than-temporary impairments	(342)	(1,282)	(4,494)	(7,827)
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0	10	0
Total net realized gains	3,688	308	2,749	15,771
Other income	2,199	698	7,018	5,521
Total revenues	581,691	540,457	1,701,912	1,586,322
Expenses:
Loss and loss expense incurred	316,258	285,161	911,881	861,721
Policy acquisition costs	193,835	174,802	567,793	509,295
Interest expense	5,714	5,610	16,940	16,826
Other expenses	10,441	9,045	35,669	29,586
Total expenses	526,248	474,618	1,532,283	1,417,428
Income before federal income tax	55,443	65,839	169,629	168,894
Federal income tax expense:
Current	5,625	9,141	38,027	29,128
Deferred	11,316	9,702	12,467	19,294
Total federal income tax expense	16,941	18,843	50,494	48,422
Net income	$ 38,502	$ 46,996	$ 119,135	$ 120,472
Earnings per share:
Basic net income	$ 0.66	$ 0.82	$ 2.06	$ 2.11
Diluted net income	0.66	0.81	2.03	2.08
Dividends to stockholders	$ 0.15	$ 0.14	$ 0.45	$ 0.42

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income	$ 38,502	$ 46,996	$ 119,135	$ 120,472
Unrealized holding (losses) gains arising during period	(8,444)	5,442	70,473	(18,132)
Non-credit portion of other-than-temporary impairments recognized in other comprehensive income	0	0	(6)	0
Amounts reclassified into net income: Held-to-maturity securities	(9)	(63)	(68)	(353)
Amounts reclassified into net income: Non-credit other-than-temporary impairments	0	0	0	232
Amounts reclassified into net income: Realized gains on available-for-sale securities	(2,395)	(199)	(1,786)	(10,906)
Total unrealized (losses) gains on investment securities	(10,848)	5,180	68,613	(29,159)
Amount reclassified into net income: Net actuarial loss	1,050	1,110	3,021	3,332
Total defined benefit pension and post-retirement plans	1,050	1,110	3,021	3,332
Other comprehensive (loss) income	(9,798)	6,290	71,634	(25,827)
Comprehensive income	$ 28,704	$ 53,286	$ 190,769	$ 94,645

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]
Beginning of year at Dec. 31, 2014		$ 199,896	$ 305,385	$ 1,313,440	$ 19,788	$ (562,923)
Dividend reinvestment plan (shares: 29,865 – 2016; 38,947 - 2015)		78	1,014
Stock purchase and compensation plans (shares: 613,964 - 2016; 686,984 - 2015)		1,374	14,588
Net income	$ 120,472			120,472
Dividends to stockholders ($0.45 per share - 2016; $0.42 per share - 2015)				(24,376)
Other comprehensive income (loss)	(25,827)				(25,827)
Acquisition of treasury stock (shares: 152,392 - 2016; 139,031 - 2015)						(3,887)
End of period at Sep. 30, 2015	1,359,022	201,348	320,987	1,409,536	(6,039)	(566,810)
Beginning of year at Dec. 31, 2015	1,398,041	201,723	326,656	1,446,192	(9,425)	(567,105)
Dividend reinvestment plan (shares: 29,865 – 2016; 38,947 - 2015)		60	1,035
Stock purchase and compensation plans (shares: 613,964 - 2016; 686,984 - 2015)		1,228	15,155
Net income	119,135			119,135
Dividends to stockholders ($0.45 per share - 2016; $0.42 per share - 2015)				(26,399)
Other comprehensive income (loss)	71,634				71,634
Acquisition of treasury stock (shares: 152,392 - 2016; 139,031 - 2015)						(4,985)
End of period at Sep. 30, 2016	$ 1,574,904	$ 203,011	$ 342,846	$ 1,538,928	$ 62,209	$ (572,090)

Consolidated Statements of Sto7

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Dividend reinvestment plan, shares			29,865	38,947
Stock purchase and compensation plans, shares			613,964	686,984
Dividends to stockholders, per share	$ 0.15	$ 0.14	$ 0.45	$ 0.42
Acquisition of treasury stock, shares			152,392	139,031
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, 2016	Sep. 30, 2015
Operating Activities
Net income	$ 119,135	$ 120,472
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45,563	43,868
Stock-based compensation expense	8,950	7,626
Undistributed losses of equity method investments	49	781
Net realized gains	(2,749)	(15,771)
Changes in assets and liabilities:
Increase in reserve for loss and loss expenses, net of reinsurance recoverables	90,814	60,065
Increase in unearned premiums, net of prepaid reinsurance	125,453	121,424
Decrease in net federal income taxes	11,534	27,980
Increase in premiums receivable	(96,425)	(95,188)
Increase in deferred policy acquisition costs	(22,775)	(28,058)
(Increase) decrease in interest and dividends due or accrued	(1,356)	979
Decrease in accrued salaries and benefits	(63,753)	(338)
Increase in other assets	(16,280)	(13,888)
(Decrease) increase in other liabilities	(20,686)	29,081
Net adjustments	58,339	138,561
Net cash provided by operating activities	177,474	259,033
Investing Activities
Purchase of fixed income securities, available-for-sale	(842,253)	(731,154)
Purchase of fixed income securities, held-to-maturity	(4,235)	0
Purchase of equity securities, available-for-sale	(24,747)	(192,717)
Purchase of other investments	(34,994)	(6,589)
Purchase of short-term investments	(1,307,024)	(1,084,794)
Sale of fixed income securities, available-for-sale	33,448	22,323
Sale of short-term investments	1,332,239	1,090,911
Redemption and maturities of fixed income securities, held-to-maturity	74,186	79,972
Redemption and maturities of fixed income securities, available-for-sale	483,877	403,510
Sale of equity securities, available-for-sale	99,420	148,228
Distributions from other investments	18,512	22,038
Purchase of property and equipment	(13,421)	(11,869)
Net cash used in investing activities	(184,992)	(260,141)
Financing Activities
Dividends to stockholders	(24,885)	(22,848)
Acquisition of treasury stock	(4,985)	(3,887)
Net proceeds from stock purchase and compensation plans	4,906	6,016
Proceeds from borrowings	105,000	15,000
Repayments of borrowings	(70,000)	0
Excess tax benefits from share-based payment arrangements	1,917	1,498
Repayments of capital lease obligations	(3,840)	(3,517)
Net cash provided by (used in) financing activities	8,113	(7,738)
Net increase (decrease) in cash	595	(8,846)
Cash, beginning of year	898	23,959
Cash, end of period	$ 1,493	$ 15,113

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2016
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 2016 presentation. Such reclassifications had no effect on our net income, stockholders' equity, or 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, 2016 (“ Third Quarter 2016 ”) and September 30, 2015 (“ Third Quarter 2015 ”) and the nine-month periods ended September 30, 2016 (" Nine Months 2016 ") and September 30, 2015 (" Nine Months 2015 "). 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, 2015 (“ 2015 Annual Report ”) filed with the SEC.

Accounting Pronouncements

Accounting Pronouncements	9 Months Ended
	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Accounting Pronouncements	Accounting Pronouncements In June 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period (“ASU 2014-12”). ASU 2014-12 requires that performance targets that affect vesting and could be achieved after the requisite service period be treated as performance conditions. The adoption of ASU 2014-12 in the first quarter of 2016 did not affect us, as we record expense consistent with the requirements of this accounting update. In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis (“ASU 2015-02”). ASU 2015-02 affects the following areas: (i) limited partnerships and similar legal entities; (ii) the evaluation of fees paid to a decision maker or a service provider as a variable interest; (iii) the effect of fee arrangements on the primary beneficiary determination; (iv) the effect of related parties on the primary beneficiary determination; and (v) certain investment funds. We adopted this guidance in the first quarter of 2016. Under the new guidance, our limited partnership and tax credit investments are variable interest entities ("VIEs"); however, we are not the primary beneficiary of any of these investments. As such, the adoption had no impact on our financial condition or results of operations. The required disclosures related to our VIEs are included in Note 4. “Investments” below. In April 2015, the FASB issued ASU 2015-05, Customer's Accounting for Fees Paid in a Cloud Computing Arrangement (“ASU 2015-05”). ASU 2015-05 provides guidance to customers with cloud computing arrangements that include a software license. If a cloud computing arrangement includes a software license, the customer's accounting for the software license element of the arrangement is consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer accounts for the arrangement as a service contract. We adopted this guidance in the first quarter of 2016, with prospective application. The impact of this adoption did not have a material effect on our financial condition or results of operations. In May 2015, the FASB issued ASU 2015-07, Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent) (“ASU 2015-07”). ASU 2015-07 provides that investments for which the practical expedient is used to measure fair value at net asset value per share ("NAV") must be removed from the fair value hierarchy. Instead, those investments must be included as a reconciling line item so that the total fair value amount of investments in the disclosure is consistent with the amount on the balance sheet. ASU 2015-07 also includes disclosure requirements for investments for which the NAV practical expedient was used to determine fair value. The adoption of this guidance in the first quarter of 2016 did not impact our financial condition or results of operations. Pronouncements to be effective in the future In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”). ASU 2014-15 is intended to define management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and provide related footnote disclosures. ASU 2014-15 is effective for annual periods ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016. Early application is permitted. As the requirements of this literature are disclosure only, ASU 2014-15 will not impact our financial condition or results of operations. In May 2015, the FASB issued ASU 2015-09, Disclosures about Short-Duration Contracts (“ASU 2015-09”). ASU 2015-09 requires companies that issue short duration contracts to disclose additional information, including: (i) incurred and paid claims development tables; (ii) frequency and severity of claims; and (iii) information about material changes in judgments made in calculating the liability for unpaid claim adjustment expenses, including reasons for the change and the effects on the financial statements. ASU 2015-09 is effective for annual periods beginning after December 15, 2015, and interim periods within annual periods beginning after December 15, 2016. ASU 2015-09 is to be applied retrospectively by providing comparative disclosures for each period presented, except for those requirements that apply only to the current period. As the requirements of this literature are disclosure only, the application of this guidance will not impact our financial condition or results of operations. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Sub-topic 825-10): 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 investments 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. ASU 2016-01 is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early application to financial statements of annual or interim periods that have not yet been issued are permitted as of the beginning of the year of adoption, otherwise early adoption of ASU 2016-01 is not permitted. We are currently evaluating the impact of this guidance on our financial condition and results of operations. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 requires all lessees to recognize a lease liability and a right-of-use asset, measured at the present value of the future minimum lease payments, at the lease commencement date. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim reporting periods within that fiscal year, with early adoption permitted. ASU 2016-02 requires the application of a modified retrospective approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. While we are currently evaluating ASU 2016-02, we do not expect a material impact on our financial condition or results of operations from the adoption of this guidance. In March 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-based Payment Accounting (“ASU 2016-09”). ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions including: (i) income tax consequences; (ii) classification of awards as either equity or liabilities; (iii) forfeitures assumptions; and (iv) cash flow classification. ASU 2016-09 is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted. While we are currently evaluating ASU 2016-09, we do not expect a material impact on our financial condition or results of operations. In June 2016, the FASB issued ASU 2016-13 , Financial Instruments - Credit Losses (“ASU 2016-13”). ASU 2016-13 will change the way entities recognize impairment of financial assets by requiring immediate recognition of estimated credit losses expected to occur over the remaining life of many financial assets, including, among others, held-to-maturity debt securities, trade receivables, and reinsurance receivables. ASU 2016-13 requires a valuation allowance to be calculated on these financial assets and that they be presented on the financial statements net of the valuation allowance. The valuation allowance is a measurement of expected losses that is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. This methodology is referred to as the current expected credit loss model. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2018. We are currently evaluating the impact of this guidance on our financial condition and results of operations. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (“ASU 2016-15”). ASU 2016-15 adds or clarifies guidance on the classification of certain cash receipts and payments in the statement of cash flows 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; (iii) distributions received from equity method investees; and (iv) separately identifiable cash flows and application of the predominance principle. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the impact of this guidance on our statement of cash flows.

Statements of Cash Flow

Statements of Cash Flow	9 Months Ended
	Sep. 30, 2016
Supplemental Cash Flow Information [Abstract]
Statements of Cash Flow	Statements of Cash Flow Supplemental cash flow information is as follows: Nine Months ended September 30, ($ in thousands) 2016 2015 Cash paid during the period for: Interest $ 13,874 13,843 Federal income tax 36,405 18,500 Non-cash items: Exchange of fixed income securities, AFS 21,775 35,425 Tax-free exchange of fixed income securities, held-to-maturity ("HTM") — 10,045 Corporate actions related to equity securities, AFS 1 3,032 4,239 Assets acquired under capital lease arrangements 3,108 6,933 Non-cash purchase of property and equipment 648 — 1 Examples of such corporate actions include non-cash acquisitions and stock splits. Included in "Other assets" on the Consolidated Balance Sheet was $20.9 million at September 30, 2016 and $9.9 million at September 30, 2015 of cash received from the National Flood Insurance Program ("NFIP"), which is restricted to pay flood claims under the Write Your Own ("WYO") program.

Investments

Investments	9 Months Ended
	Sep. 30, 2016
Investments [Abstract]
Investments	Investments (a) Information regarding our HTM fixed income securities as of September 30, 2016 and December 31, 2015 was as follows: September 30, 2016 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states and political subdivisions $ 104,159 414 104,573 3,256 — 107,829 Corporate securities 23,722 (165 ) 23,557 2,294 — 25,851 Asset-backed securities (“ABS”) 51 — 51 — — 51 Commercial mortgage-backed securities (“CMBS”) 2,346 (55 ) 2,291 72 — 2,363 Total HTM fixed income securities $ 130,278 194 130,472 5,622 — 136,094 December 31, 2015 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states and political subdivisions $ 175,269 848 176,117 5,763 — 181,880 Corporate securities 20,228 (185 ) 20,043 1,972 — 22,015 ABS 1,030 (120 ) 910 118 — 1,028 CMBS 4,527 (243 ) 4,284 337 — 4,621 Total HTM fixed income securities $ 201,054 300 201,354 8,190 — 209,544 Unrecognized holding gains and losses of HTM securities are not reflected in the Financial Statements, as they represent fair value fluctuations from the later of: (i) the date a security is designated as HTM; or (ii) the date that an other-than-temporary impairment (“OTTI”) charge is recognized on an HTM security, through the date of the balance sheet. Our HTM securities had an average duration of 1.6 years as of September 30, 2016 . (b) Information regarding our AFS securities as of September 30, 2016 and December 31, 2015 was as follows: September 30, 2016 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 86,491 3,400 — 89,891 Foreign government 9,041 443 — 9,484 Obligations of states and political subdivisions 1,376,245 70,984 (333 ) 1,446,896 Corporate securities 2,136,761 60,784 (1,427 ) 2,196,118 ABS 282,558 1,964 (69 ) 284,453 CMBS 261,233 5,634 (93 ) 266,774 Residential mortgage-backed securities (“RMBS”) 529,938 9,294 (316 ) 538,916 Total AFS fixed income securities 4,682,267 152,503 (2,238 ) 4,832,532 AFS equity securities: Common stock 111,746 24,832 (1,089 ) 135,489 Preferred stock 11,235 580 — 11,815 Total AFS equity securities 122,981 25,412 (1,089 ) 147,304 Total AFS securities $ 4,805,248 177,915 (3,327 ) 4,979,836 December 31, 2015 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 99,485 4,721 (91 ) 104,115 Foreign government 14,885 298 (2 ) 15,181 Obligations of states and political subdivisions 1,314,779 44,523 (160 ) 1,359,142 Corporate securities 1,892,296 23,407 (15,521 ) 1,900,182 ABS 244,541 531 (918 ) 244,154 CMBS 245,252 750 (2,410 ) 243,592 RMBS 541,276 4,274 (3,713 ) 541,837 Total AFS fixed income securities 4,352,514 78,504 (22,815 ) 4,408,203 AFS equity securities: Common stock 181,991 14,796 (1,998 ) 194,789 Preferred stock 11,825 477 (40 ) 12,262 Total AFS equity securities 193,816 15,273 (2,038 ) 207,051 Total AFS securities $ 4,546,330 93,777 (24,853 ) 4,615,254 Unrealized gains and losses of AFS securities represent fair value fluctuations from the later of: (i) the date a security is designated as AFS; or (ii) the date that an OTTI charge is recognized on an AFS security, through the date of the balance sheet. These unrealized gains and losses are recorded in "Accumulated other comprehensive income (loss)" ("AOCI") on the Consolidated Balance Sheets. (c) The following tables provide information regarding our AFS securities in a net unrealized loss position at September 30, 2016 and December 31, 2015 : September 30, 2016 Less than 12 months 12 months or longer ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 AFS fixed income securities: Obligations of states and political subdivisions $ 74,989 (333 ) — — Corporate securities 155,880 (1,139 ) 30,469 (288 ) ABS 21,766 (66 ) 2,450 (3 ) CMBS 24,633 (59 ) 8,709 (34 ) RMBS 13,674 (40 ) 37,677 (276 ) Total AFS fixed income securities 290,942 (1,637 ) 79,305 (601 ) AFS equity securities: Common stock 12,528 (1,089 ) — — Total AFS equity securities 12,528 (1,089 ) — — Total AFS $ 303,470 (2,726 ) 79,305 (601 ) December 31, 2015 Less than 12 months 12 months or longer ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 AFS fixed income securities: U.S. government and government agencies $ 16,006 (87 ) 396 (4 ) Foreign government 1,067 (2 ) — — Obligations of states and political subdivisions 28,617 (160 ) — — Corporate securities 761,479 (12,671 ) 50,382 (2,850 ) ABS 197,477 (807 ) 12,022 (111 ) CMBS 146,944 (2,196 ) 15,385 (214 ) RMBS 264,914 (1,992 ) 63,395 (1,721 ) Total AFS fixed income securities 1,416,504 (17,915 ) 141,580 (4,900 ) AFS equity securities: Common stock 31,148 (1,998 ) — — Preferred stock 1,531 (40 ) — — Total AFS equity securities 32,679 (2,038 ) — — Total AFS $ 1,449,183 (19,953 ) 141,580 (4,900 ) 1 Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI. There were no net unrealized/unrecognized losses on our HTM portfolio as of September 30, 2016 . The table below provides our net unrealized/unrecognized loss positions by impairment severity for AFS securities as of September 30, 2016 and for both AFS and HTM securities as of December 31, 2015 : ($ in thousands) September 30, 2016 December 31, 2015 Number of Issues % of Market/Book Unrealized Loss Number of Issues % of Market/Book Unrealized/ Unrecognized Loss 180 80% - 99% $ 3,327 606 80% - 99% $ 22,971 — 60% - 79% — 3 60% - 79% 1,888 — 40% - 59% — — 40% - 59% — — 20% - 39% — — 20% - 39% — — 0% - 19% — — 0% - 19% — $ 3,327 $ 24,859 We do not intend to sell any of the securities in the tables above, nor do we believe we will be required to sell any of these securities. We have also reviewed 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 2015 Annual Report , and have concluded that they are temporarily impaired. 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. Additionally, changes in market value due to interest rate fluctuations are considered temporary. If our judgment about an individual security changes in the future, we may ultimately record a credit loss after having originally concluded that one did not exist, which could have a material impact on our net income and financial position in future periods. (d) Fixed income securities at September 30, 2016 , by contractual maturity, are shown below. Mortgage-backed securities ("MBS") 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 HTM fixed income securities at September 30, 2016 : ($ in thousands) Carrying Value Fair Value Due in one year or less $ 59,074 59,671 Due after one year through five years 62,778 66,622 Due after five years through 10 years 8,620 9,801 Total HTM fixed income securities $ 130,472 136,094 Listed below are the contractual maturities of AFS fixed income securities at September 30, 2016 : ($ in thousands) Fair Value Due in one year or less $ 491,206 Due after one year through five years 2,403,246 Due after five years through 10 years 1,823,028 Due after 10 years 115,052 Total AFS fixed income securities $ 4,832,532 (e) We evaluate the alternative investments and tax credit investments included in our other investments portfolio to determine whether those investments are VIEs and if so, whether consolidation is required. A VIE is an entity that either has equity investors that lack certain essential characteristics of a controlling financial interest or lacks sufficient funds to finance its own activities without financial support provided by other entities. We consider several significant factors in determining if our investments are VIEs and if we are the primary beneficiary, including whether we have: (i) the power to direct activities of the VIE; (ii) the ability to remove the decision maker of the VIE; (iii) the ability to participate in making decisions that are significant to the VIE; and (iv) the obligation to absorb losses and the right to receive benefits that could potentially be significant to the VIE. We have determined that the investments in our other investment portfolio are VIEs, but that we are not the primary beneficiary and therefore, consolidation is not required. The following table summarizes our other investment portfolio by strategy: Other Investments September 30, 2016 December 31, 2015 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Alternative Investments Private equity $ 35,444 57,793 93,237 35,088 30,204 65,292 Private credit 27,709 30,763 58,472 13,246 15,129 28,375 Real assets 15,329 22,922 38,251 19,500 25,820 45,320 Total alternative investments 78,482 111,478 189,960 67,834 71,153 138,987 Other securities 10,030 22,611 32,641 10,008 3,200 13,208 Total other investments $ 88,512 134,089 222,601 77,842 74,353 152,195 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 2016 or 2015. In addition to the strategy descriptions included in Note 5. “Investments” in Item 8. “Financial Statements and Supplementary Data.” of our 2015 Annual Report , our private credit strategy now includes middle market lending, which is a strategy that provides privately negotiated loans to U.S. middle market companies. Typically, these are floating rate, senior secured loans diversified across industries. Loans can be made to private equity sponsor-backed companies or non-sponsored companies to finance leveraged buyouts, recapitalizations, and acquisitions. 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 as follows: Income Statement Information Quarter ended June 30, Nine months ended June 30, ($ in millions) 2016 2015 2016 2015 Net investment (loss) income $ (55.4 ) 44.1 26.1 139.6 Realized gains 245.6 385.2 1,186.8 977.7 Net change in unrealized depreciation 117.8 (222.2 ) (1,132.8 ) (1,089.0 ) Net gain $ 308.0 207.1 80.1 28.3 Selective’s insurance subsidiaries’ other investments gain (loss) $ 1.6 1.3 — (0.8 ) (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, 2016 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, 2016 : ($ in millions) FHLBI Collateral FHLBNY Collateral State and Regulatory Deposits Total U.S. government and government agencies $ 7.4 — 23.1 30.5 CMBS 1.0 — — 1.0 RMBS 53.1 64.4 — 117.5 Total pledged as collateral $ 61.5 64.4 23.1 149.0 (g) The Company did not have exposure to any credit concentration risk of a single issuer greater than 10% of the Company's stockholders' equity, other than certain U.S. government-backed investments, as of September 30, 2016 or December 31, 2015 . (h) The components of pre-tax net investment income earned for the periods indicated were as follows: Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Fixed income securities $ 32,453 30,601 $ 95,850 92,227 Equity securities 1,506 2,370 5,940 6,546 Short-term investments 192 24 493 72 Other investments 1,628 1,337 (49 ) (781 ) Investment expenses (2,404 ) (2,271 ) (6,908 ) (6,856 ) Net investment income earned $ 33,375 32,061 $ 95,326 91,208 (i) The following tables summarize OTTI by asset type for the periods indicated: Third Quarter 2016 Gross Included in Other Comprehensive Income ("OCI") Recognized in ($ in thousands) AFS equity securities: Common stock $ 342 — 342 Total AFS equity securities 342 — 342 Total OTTI losses $ 342 — 342 Third Quarter 2015 Gross Included in OCI Recognized in ($ in thousands) AFS fixed income securities: Corporate securities $ 253 — 253 Total AFS fixed income securities 253 — 253 AFS equity securities: Common stock 1,029 — 1,029 Total AFS equity securities 1,029 — 1,029 Total OTTI losses $ 1,282 — 1,282 Nine Months 2016 Gross Included in OCI Recognized in ($ in thousands) AFS fixed income securities: Corporate securities $ 1,077 — 1,077 RMBS 98 10 88 Total AFS fixed income securities 1,175 10 1,165 AFS equity securities: Common stock 3,316 — 3,316 Preferred stock 3 — 3 Total AFS equity securities 3,319 — 3,319 Total OTTI losses $ 4,494 10 4,484 Nine Months 2015 Gross Included in OCI Recognized in ($ in thousands) AFS fixed income securities: Corporate securities $ 1,445 — 1,445 RMBS 1 — 1 Total AFS fixed income securities 1,446 — 1,446 AFS equity securities: Common stock 6,201 — 6,201 Preferred stock 180 — 180 Total AFS equity securities 6,381 — 6,381 Total OTTI losses $ 7,827 — 7,827 For a discussion of our evaluation for OTTI of fixed income securities, short-term investments, equity securities, and other investments, refer to Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2015 Annual Report . (j) The components of net realized gains, excluding OTTI charges, for the periods indicated were as follows: Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 HTM fixed income securities Gains $ — 3 3 5 Losses — — (1 ) (1 ) AFS fixed income securities Gains 2,204 169 3,189 2,158 Losses (40 ) — (81 ) (130 ) AFS equity securities Gains 1,863 1,419 4,364 23,567 Losses — (1 ) (240 ) (1,347 ) Other investments Gains 3 — 3 — Losses — — (4 ) (654 ) Total net realized gains (excluding OTTI charges) $ 4,030 1,590 7,233 23,598 Realized gains and losses on the sale of investments are determined on the basis of the cost of the specific investments sold. Proceeds from the sale of AFS securities were $27.0 million and $12.7 million in Third Quarter 2016 and Third Quarter 2015 , respectively, and $132.9 million and $170.6 million in Nine Months 2016 and Nine Months 2015 , respectively. The $23.6 million in net realized gains for Nine Months 2015 were primarily due to a change in our dividend equity strategy from a quantitative, model-driven stock selection strategy to a fundamentally-based stock selection approach that incorporates an assessment of the sustainability and growth rate of a company’s dividends and future cash flow.

Indebtedness

Indebtedness	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Indebtedness	NOTE 5. Indebtedness During Nine Months 2016 , Selective Insurance Company of America ("SICA") borrowed the following short-term funds from the FHLBNY: • $25 million on February 26, 2016 at an interest rate of 0.59% , which was repaid on March 18, 2016; • $15 million on April 7, 2016 at an interest rate of 0.52% , which was repaid on April 28, 2016; and • $15 million on April 28, 2016 at an interest rate of 0.53% , which was repaid on May 19, 2016. During Nine Months 2016 , SICA borrowed the following long-term funds from the FHLBNY: • $25 million on July 21, 2016 at an interest rate of 1.61% , which is due on July 21, 2021; and • $25 million on August 15, 2016 at an interest rate of 1.56% , which is due on August 16, 2021. Additionally, in Third Quarter 2016, Selective Insurance Company of the Southeast and Selective Insurance Company of South Carolina repaid their $15 million outstanding aggregate borrowing from the FHLBI. For further information on our indebtedness, see Note 10. "Indebtedness" in Item 8. "Financial Statements and Supplementary Data." of our 2015 Annual Report .

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following table presents the carrying amounts and estimated fair values of our financial instruments as of September 30, 2016 and December 31, 2015 : September 30, 2016 December 31, 2015 ($ in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial Assets Fixed income securities: HTM $ 130,472 136,094 201,354 209,544 AFS 4,832,532 4,832,532 4,408,203 4,408,203 Equity securities, AFS 147,304 147,304 207,051 207,051 Short-term investments 169,604 169,604 194,819 194,819 Financial Liabilities Short-term debt: 0.63% borrowings from FHLBI $ — — 15,000 14,977 1.25% borrowings from FHLBI 45,000 45,072 45,000 45,083 Total short-term debt $ 45,000 45,072 60,000 60,060 Long-term debt: 7.25% Senior Notes $ 49,900 60,682 49,898 56,929 6.70% Senior Notes 99,426 118,192 99,415 110,363 5.875% Senior Notes 185,000 194,324 185,000 192,474 1.61% borrowings from FHLBNY 25,000 25,048 — — 1.56% borrowings from FHLBNY 25,000 24,990 — — Subtotal long-term debt 384,326 423,236 334,313 359,766 Unamortized debt issuance costs (5,775 ) (6,121 ) Total long-term debt $ 378,551 328,192 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 2015 Annual Report . The following tables provide quantitative disclosures of our financial assets that were measured at fair value at September 30, 2016 and December 31, 2015 : September 30, 2016 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 $ 89,891 35,147 54,744 — Foreign government 9,484 — 9,484 — Obligations of states and political subdivisions 1,446,896 — 1,446,896 — Corporate securities 2,196,118 — 2,196,118 — ABS 284,453 — 284,453 — CMBS 266,774 — 266,774 — RMBS 538,916 — 538,916 — Total AFS fixed income securities 4,832,532 35,147 4,797,385 — AFS equity securities: Common stock 135,489 127,813 — 7,676 Preferred stock 11,815 11,815 — — Total AFS equity securities 147,304 139,628 — 7,676 Total AFS securities 4,979,836 174,775 4,797,385 7,676 Short-term investments 169,604 169,604 — — Total assets measured at fair value $ 5,149,440 344,379 4,797,385 7,676 December 31, 2015 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 $ 104,115 42,702 61,413 — Foreign government 15,181 — 15,181 — Obligations of states and political subdivisions 1,359,142 — 1,359,142 — Corporate securities 1,900,182 — 1,900,182 — ABS 244,154 — 244,154 — CMBS 243,592 — 243,592 — RMBS 541,837 — 541,837 — Total AFS fixed income securities 4,408,203 42,702 4,365,501 — AFS equity securities: Common stock 194,789 191,517 — 3,272 Preferred stock 12,262 12,262 — — Total AFS equity securities 207,051 203,779 — 3,272 Total AFS securities 4,615,254 246,481 4,365,501 3,272 Short-term investments 194,819 194,819 — — Total assets measured at fair value $ 4,810,073 441,300 4,365,501 3,272 1 There were no transfers of securities between Level 1 and Level 2. The following table provides a summary of the changes in the fair value of securities measured using Level 3 inputs and related quantitative information for the nine -month period ended September 30, 2016 : September 30, 2016 Common Stock ($ in thousands) Fair value, December 31, 2015 $ 3,272 Total net (losses) gains for the period included in: OCI — Net income — Purchases 6,204 Sales (1,800 ) Issuances — Settlements — Transfers into Level 3 — Transfers out of Level 3 — Fair value, September 30, 2016 $ 7,676 The following tables provide quantitative information regarding our financial assets and liabilities that were disclosed at fair value at September 30, 2016 and December 31, 2015 : September 30, 2016 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 $ 107,829 — 107,829 — Corporate securities 25,851 — 18,160 7,691 ABS 51 — 51 — CMBS 2,363 — 2,363 — Total HTM fixed income securities $ 136,094 — 128,403 7,691 Financial Liabilities Short-term debt: 1.25% borrowings from FHLBI $ 45,072 — 45,072 — Total short-term debt $ 45,072 — 45,072 — Long-term debt: 7.25% Senior Notes $ 60,682 — 60,682 — 6.70% Senior Notes 118,192 — 118,192 — 5.875% Senior Notes 194,324 194,324 — — 1.61% borrowings from FHLBNY 25,048 — 25,048 — 1.56% borrowings from FHLBNY 24,990 — 24,990 — Total long-term debt $ 423,236 194,324 228,912 — December 31, 2015 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 $ 181,880 — 181,880 — Corporate securities 22,015 — 18,679 3,336 ABS 1,028 — 1,028 — CMBS 4,621 — 4,621 — Total HTM fixed income securities $ 209,544 — 206,208 3,336 Financial Liabilities Short-term debt: 0.63% borrowings from FHLBI $ 14,977 — 14,977 — 1.25% borrowings from FHLBI 45,083 — 45,083 — Total short-term debt $ 60,060 — 60,060 — Long-term debt: 7.25% Senior Notes $ 56,929 — 56,929 — 6.70% Senior Notes 110,363 — 110,363 — 5.875% Senior Notes 192,474 192,474 — — Total long-term debt $ 359,766 192,474 167,292 —

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2016
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 2015 Annual Report . Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Premiums written: Direct $ 669,844 631,429 $ 1,981,984 1,851,620 Assumed 7,644 6,099 21,752 17,140 Ceded (98,715 ) (92,503 ) (281,464 ) (273,514 ) Net $ 578,773 545,025 $ 1,722,272 1,595,246 Premiums earned: Direct $ 627,520 590,716 $ 1,846,587 1,728,865 Assumed 7,163 5,830 20,604 16,831 Ceded (92,254 ) (89,156 ) (270,372 ) (271,874 ) Net $ 542,429 507,390 $ 1,596,819 1,473,822 Loss and loss expense incurred: Direct $ 428,520 306,635 $ 1,152,223 935,529 Assumed 5,929 4,224 18,424 13,114 Ceded (118,191 ) (25,698 ) (258,766 ) (86,922 ) Net $ 316,258 285,161 $ 911,881 861,721 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) 2016 2015 2016 2015 Ceded premiums written $ (62,051 ) (62,463 ) $ (179,205 ) (178,784 ) Ceded premiums earned (56,505 ) (58,340 ) (169,986 ) (176,119 ) Ceded loss and loss expense incurred (99,200 ) (15,382 ) (164,179 ) (36,315 )

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Segment Information	Segment Information We classify our business into four reportable segments, which are as follows: • Standard Commercial Lines - comprised of insurance products and services provided in the standard marketplace to commercial enterprises, which are typically businesses, non-profit organizations, and local government agencies. • Standard Personal Lines - comprised of insurance products and services, including flood insurance coverage, provided primarily to individuals acquiring coverage in the standard marketplace. • E&S Lines - comprised of insurance products and services provided to customers who have not obtained coverage in the standard marketplace. • Investments - invests the premiums collected by our insurance operations, as well as our earnings and amounts generated through our capital management strategies, which may include the issuance of debt and equity securities. In computing the results of each segment, we do not make adjustments for interest expense or net general corporate expenses. While we do not fully allocate taxes to all segments, we do allocate taxes to our Investments segment as we manage that segment on after-tax results. 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 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) 2016 2015 2016 2015 Standard Commercial Lines: Net premiums earned: Commercial automobile $ 100,612 90,758 294,927 265,771 Workers compensation 78,596 74,560 229,847 213,991 General liability 133,981 123,252 391,349 357,430 Commercial property 74,052 68,587 217,821 199,699 Businessowners’ policies 24,461 23,726 73,016 69,603 Bonds 5,795 5,031 16,924 15,137 Other 4,089 3,628 11,868 10,649 Miscellaneous income 1,925 448 6,182 4,680 Total Standard Commercial Lines revenue 423,511 389,990 1,241,934 1,136,960 Standard Personal Lines: Net premiums earned: Personal automobile 34,865 36,623 106,526 110,373 Homeowners 32,031 33,670 98,342 101,122 Other 1,794 1,795 4,851 5,143 Miscellaneous income 275 250 836 841 Total Standard Personal Lines revenue 68,965 72,338 210,555 217,479 E&S Lines: Net premiums earned: General liability 37,398 32,395 108,372 87,914 Commercial property 11,853 11,309 35,013 31,428 Commercial automobile 2,902 2,056 7,963 5,562 Miscellaneous income (1 ) — — — Total E&S Lines revenue 52,152 45,760 151,348 124,904 Investments: Net investment income 33,375 32,061 95,326 91,208 Net realized investment gains 3,688 308 2,749 15,771 Total Investments revenue 37,063 32,369 98,075 106,979 Total revenues $ 581,691 540,457 1,701,912 1,586,322 Income Before Federal Income Tax Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Standard Commercial Lines: Underwriting gain $ 30,124 44,027 101,229 109,304 GAAP combined ratio 92.9 % 88.7 91.8 90.3 Statutory combined ratio 92.0 88.4 90.1 89.4 Standard Personal Lines: Underwriting gain (loss) $ 4,271 2,826 19,001 (4,295 ) GAAP combined ratio 93.8 % 96.1 90.9 102.0 Statutory combined ratio 92.0 95.0 90.7 101.7 E&S Insurance Operations: Underwriting loss $ (2,362 ) (2,022 ) (3,465 ) (5,033 ) GAAP combined ratio 104.5 % 104.4 102.3 104.0 Statutory combined ratio 101.4 101.1 100.9 101.8 Investments: Net investment income $ 33,375 32,061 95,326 91,208 Net realized investment gains 3,688 308 2,749 15,771 Total investment income, before federal income tax 37,063 32,369 98,075 106,979 Tax on investment income 9,752 7,614 24,290 26,186 Total investment income, after federal income tax $ 27,311 24,755 73,785 80,793 Reconciliation of Segment Results to Income Before Federal Income Tax Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Underwriting gain (loss), before federal income tax Standard Commercial Lines $ 30,124 44,027 101,229 109,304 Standard Personal Lines 4,271 2,826 19,001 (4,295 ) E&S Lines (2,362 ) (2,022 ) (3,465 ) (5,033 ) Investment income, before federal income tax 37,063 32,369 98,075 106,979 Total all segments 69,096 77,200 214,840 206,955 Interest expense (5,714 ) (5,610 ) (16,940 ) (16,826 ) General corporate and other expenses (7,939 ) (5,751 ) (28,271 ) (21,235 ) Income before federal income tax $ 55,443 65,839 169,629 168,894

Retirement Plans

Retirement Plans	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [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 2015 Annual Report . The following tables provide information regarding the Pension Plan: Pension Plan Pension Plan ($ in thousands) 2016 2015 2016 2015 Net Periodic Benefit Cost: Service cost $ 41 1,913 1,647 5,738 Interest cost 3,049 3,409 9,252 10,225 Expected return on plan assets (5,006 ) (3,991 ) (12,982 ) (11,972 ) Amortization of unrecognized net actuarial loss 1,763 1,643 4,724 4,930 Total net periodic cost $ (153 ) 2,974 2,641 8,921 As of December 31, 2015, we anticipated contributing $11.7 million to the Pension Plan for full year 2016. Actual contributions amounted to $54.5 million in Nine Months 2016 and we do not anticipate any additional funding this year. The decrease in net periodic cost in Third Quarter 2016 reflects lower expense as a result of the contributions that were higher than our original expectation. Pension Plan 2016 2015 Weighted-Average Expense Assumptions: Discount rate 4.69 % 4.29 % Effective interest rate for calculation of service cost 4.89 % — % Effective interest rate for calculation of interest cost 4.02 % — % Expected return on plan assets 6.37 % 6.27 % Rate of compensation increase 1 n/a 4.00 % 1 This assumption was 4.0% through March 31, 2016, the date after which benefits ceased accruing for all participants of the Pension Plan. Effective January 1, 2016, the approach used to calculate the service and interest components of net periodic benefit cost for the Pension Plan was changed to provide a more precise measurement of these costs. Historically, we calculated the service and interest components utilizing a single weighted-average discount rate derived from the yield curve used to measure the benefit obligation at the beginning of the period. On January 1, 2016, we elected to utilize an approach that discounts the individual expected cash flows using the applicable spot rates derived from the yield curve over the projected cash flow period. We accounted for this change prospectively as a change in accounting estimate. The decrease in service cost reflected in the table above is attributable to the discontinuation of benefit accruals for existing participants as of March 31, 2016.

Comprehensive Income

Comprehensive Income	9 Months Ended
	Sep. 30, 2016
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 2016 and 2015 were as follows: Third Quarter 2016 ($ in thousands) Gross Tax Net Net income $ 55,443 16,941 38,502 Components of OCI: Unrealized losses on investment securities : Unrealized holding losses during period (12,992 ) (4,548 ) (8,444 ) Amounts reclassified into net income: HTM securities (13 ) (4 ) (9 ) Realized gains on AFS securities (3,684 ) (1,289 ) (2,395 ) Total unrealized losses on investment securities (16,689 ) (5,841 ) (10,848 ) Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,615 565 1,050 Total defined benefit pension and post-retirement plans 1,615 565 1,050 Other comprehensive loss (15,074 ) (5,276 ) (9,798 ) Comprehensive income $ 40,369 11,665 28,704 Third Quarter 2015 ($ in thousands) Gross Tax Net Net income $ 65,839 18,843 46,996 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 8,371 2,929 5,442 Amounts reclassified into net income: HTM securities (97 ) (34 ) (63 ) Realized gains on AFS securities (305 ) (106 ) (199 ) Total unrealized gains on investment securities 7,969 2,789 5,180 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,709 599 1,110 Total defined benefit pension and post-retirement plans 1,709 599 1,110 Other comprehensive income 9,678 3,388 6,290 Comprehensive income $ 75,517 22,231 53,286 Nine Months 2016 ($ in thousands) Gross Tax Net Net income $ 169,629 50,494 119,135 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 108,420 37,947 70,473 Non-credit portion of OTTI recognized in OCI (10 ) (4 ) (6 ) Amounts reclassified into net income: HTM securities (104 ) (36 ) (68 ) Realized gains on AFS securities (2,747 ) (961 ) (1,786 ) Total unrealized gains on investment securities 105,559 36,946 68,613 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 4,648 1,627 3,021 Total defined benefit pension and post-retirement plans 4,648 1,627 3,021 Other comprehensive income 110,207 38,573 71,634 Comprehensive income $ 279,836 89,067 190,769 Nine Months 2015 ($ in thousands) Gross Tax Net Net income $ 168,894 48,422 120,472 Components of OCI: Unrealized losses on investment securities : Unrealized holding losses during period (27,896 ) (9,764 ) (18,132 ) Amounts reclassified into net income: HTM securities (543 ) (190 ) (353 ) Non-credit OTTI 357 125 232 Realized gains on AFS securities (16,778 ) (5,872 ) (10,906 ) Total unrealized losses on investment securities (44,860 ) (15,701 ) (29,159 ) Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 5,127 1,795 3,332 Total defined benefit pension and post-retirement plans 5,127 1,795 3,332 Other comprehensive loss (39,733 ) (13,906 ) (25,827 ) Comprehensive income $ 129,161 34,516 94,645 The balances of, and changes in, each component of AOCI (net of taxes) as of September 30, 2016 were as follows: September 30, 2016 Defined Benefit Pension and Post-Retirement Plans Net Unrealized Gain on Investment Securities Total AOCI ($ in thousands) OTTI Related HTM Related All Other Investments Subtotal Balance, December 31, 2015 $ (282 ) 194 45,083 44,995 (54,420 ) (9,425 ) OCI before reclassifications (6 ) — 70,473 70,467 — 70,467 Amounts reclassified from AOCI — (68 ) (1,786 ) (1,854 ) 3,021 1,167 Net current period OCI (6 ) (68 ) 68,687 68,613 3,021 71,634 Balance, September 30, 2016 $ (288 ) 126 113,770 113,608 (51,399 ) 62,209 The reclassifications out of AOCI were as follows: Quarter ended Nine Months ended Affected Line Item in the Unaudited Consolidated Statement of Income ($ in thousands) 2016 2015 2016 2015 OTTI related Non-credit OTTI on disposed securities $ — — — 357 Net realized gains — — — 357 Income before federal income tax — — — (125 ) Total federal income tax expense — — — 232 Net income HTM related Unrealized losses on HTM disposals 73 121 161 258 Net realized gains Amortization of net unrealized gains on HTM securities (86 ) (218 ) (265 ) (801 ) Net investment income earned (13 ) (97 ) (104 ) (543 ) Income before federal income tax 4 34 36 190 Total federal income tax expense (9 ) (63 ) (68 ) (353 ) Net income Realized losses (gains) on AFS and OTTI Realized losses (gains) on AFS disposals and OTTI (3,684 ) (305 ) (2,747 ) (16,778 ) Net realized gains (3,684 ) (305 ) (2,747 ) (16,778 ) Income before federal income tax 1,289 106 961 5,872 Total federal income tax expense (2,395 ) (199 ) (1,786 ) (10,906 ) Net income Defined benefit pension and post-retirement life plans Net actuarial loss 351 371 1,009 1,114 Loss and loss expense incurred 1,264 1,338 3,639 4,013 Policy acquisition costs Total defined benefit pension and post-retirement life 1,615 1,709 4,648 5,127 Income before federal income tax (565 ) (599 ) (1,627 ) (1,795 ) Total federal income tax expense 1,050 1,110 3,021 3,332 Net income Total reclassifications for the period $ (1,354 ) 848 1,167 (7,695 ) Net income

Litigation

Litigation	9 Months Ended
	Sep. 30, 2016
Loss Contingency, Information about Litigation Matters [Abstract]
Litigation	Litigation In the ordinary course of conducting business, we are named as defendants in various legal proceedings. Most of these proceedings are claims litigation involving our insurance subsidiaries as either: (i) liability insurers defending or providing indemnity for third-party claims brought against our customers; or (ii) insurers defending first-party coverage claims brought against them. We account for such activity through the establishment of unpaid loss and loss expense reserves. We expect that the ultimate liability, if any, with respect to such ordinary course claims litigation, after consideration of provisions made for potential losses and costs of defense, will not be material to our consolidated financial condition, results of operations, or cash flows. Our insurance subsidiaries are also from time to time involved 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. Our insurance subsidiaries also are involved from time to time in individual actions in which extra-contractual damages, punitive damages, or penalties are sought, such as claims alleging bad faith in the handling of insurance claims. We believe that we have valid defenses to these cases. We expect that the ultimate liability, if any, with respect to such lawsuits, after consideration of provisions made for estimated losses, will not be material to our consolidated financial condition. Nonetheless, given the large or indeterminate amounts sought in certain of these actions, and the inherent unpredictability of litigation, an adverse outcome in certain matters could, from time to time, have a material adverse effect on our consolidated results of operations or cash flows in particular quarterly or annual periods. As of September 30, 2016 , 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, 2016
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Hurricane Matthew impacted the Southern United States in October 2016. We currently estimate catastrophe losses from this event to range from $10 million to $14 million in the fourth quarter of 2016. In addition, we currently estimate a partial offset of approximately $1 million related to the servicing of policies impacted by this event through our participation in the NFIP.

Statements of Cash Flow (Tables

Statements of Cash Flow (Tables)	9 Months Ended
	Sep. 30, 2016
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Nine Months ended September 30, ($ in thousands) 2016 2015 Cash paid during the period for: Interest $ 13,874 13,843 Federal income tax 36,405 18,500 Non-cash items: Exchange of fixed income securities, AFS 21,775 35,425 Tax-free exchange of fixed income securities, held-to-maturity ("HTM") — 10,045 Corporate actions related to equity securities, AFS 1 3,032 4,239 Assets acquired under capital lease arrangements 3,108 6,933 Non-cash purchase of property and equipment 648 — 1 Examples of such corporate actions include non-cash acquisitions and stock splits.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2016
Investments [Line Items]
Schedule of Held-to-maturity Securities	September 30, 2016 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states and political subdivisions $ 104,159 414 104,573 3,256 — 107,829 Corporate securities 23,722 (165 ) 23,557 2,294 — 25,851 Asset-backed securities (“ABS”) 51 — 51 — — 51 Commercial mortgage-backed securities (“CMBS”) 2,346 (55 ) 2,291 72 — 2,363 Total HTM fixed income securities $ 130,278 194 130,472 5,622 — 136,094 December 31, 2015 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states and political subdivisions $ 175,269 848 176,117 5,763 — 181,880 Corporate securities 20,228 (185 ) 20,043 1,972 — 22,015 ABS 1,030 (120 ) 910 118 — 1,028 CMBS 4,527 (243 ) 4,284 337 — 4,621 Total HTM fixed income securities $ 201,054 300 201,354 8,190 — 209,544
Schedule of Available-for-sale Securities	September 30, 2016 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 86,491 3,400 — 89,891 Foreign government 9,041 443 — 9,484 Obligations of states and political subdivisions 1,376,245 70,984 (333 ) 1,446,896 Corporate securities 2,136,761 60,784 (1,427 ) 2,196,118 ABS 282,558 1,964 (69 ) 284,453 CMBS 261,233 5,634 (93 ) 266,774 Residential mortgage-backed securities (“RMBS”) 529,938 9,294 (316 ) 538,916 Total AFS fixed income securities 4,682,267 152,503 (2,238 ) 4,832,532 AFS equity securities: Common stock 111,746 24,832 (1,089 ) 135,489 Preferred stock 11,235 580 — 11,815 Total AFS equity securities 122,981 25,412 (1,089 ) 147,304 Total AFS securities $ 4,805,248 177,915 (3,327 ) 4,979,836 December 31, 2015 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 99,485 4,721 (91 ) 104,115 Foreign government 14,885 298 (2 ) 15,181 Obligations of states and political subdivisions 1,314,779 44,523 (160 ) 1,359,142 Corporate securities 1,892,296 23,407 (15,521 ) 1,900,182 ABS 244,541 531 (918 ) 244,154 CMBS 245,252 750 (2,410 ) 243,592 RMBS 541,276 4,274 (3,713 ) 541,837 Total AFS fixed income securities 4,352,514 78,504 (22,815 ) 4,408,203 AFS equity securities: Common stock 181,991 14,796 (1,998 ) 194,789 Preferred stock 11,825 477 (40 ) 12,262 Total AFS equity securities 193,816 15,273 (2,038 ) 207,051 Total AFS securities $ 4,546,330 93,777 (24,853 ) 4,615,254
Schedule of Fair Value and Gross Pre-Tax Net Unrealized/Unrecognized Loss of Securities by Length of Time	September 30, 2016 Less than 12 months 12 months or longer ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 AFS fixed income securities: Obligations of states and political subdivisions $ 74,989 (333 ) — — Corporate securities 155,880 (1,139 ) 30,469 (288 ) ABS 21,766 (66 ) 2,450 (3 ) CMBS 24,633 (59 ) 8,709 (34 ) RMBS 13,674 (40 ) 37,677 (276 ) Total AFS fixed income securities 290,942 (1,637 ) 79,305 (601 ) AFS equity securities: Common stock 12,528 (1,089 ) — — Total AFS equity securities 12,528 (1,089 ) — — Total AFS $ 303,470 (2,726 ) 79,305 (601 ) December 31, 2015 Less than 12 months 12 months or longer ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 AFS fixed income securities: U.S. government and government agencies $ 16,006 (87 ) 396 (4 ) Foreign government 1,067 (2 ) — — Obligations of states and political subdivisions 28,617 (160 ) — — Corporate securities 761,479 (12,671 ) 50,382 (2,850 ) ABS 197,477 (807 ) 12,022 (111 ) CMBS 146,944 (2,196 ) 15,385 (214 ) RMBS 264,914 (1,992 ) 63,395 (1,721 ) Total AFS fixed income securities 1,416,504 (17,915 ) 141,580 (4,900 ) AFS equity securities: Common stock 31,148 (1,998 ) — — Preferred stock 1,531 (40 ) — — Total AFS equity securities 32,679 (2,038 ) — — Total AFS $ 1,449,183 (19,953 ) 141,580 (4,900 ) 1 Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI.
Schedule of The Number Of Securities In An Unrealized Unrecognized Loss Position	($ in thousands) September 30, 2016 December 31, 2015 Number of Issues % of Market/Book Unrealized Loss Number of Issues % of Market/Book Unrealized/ Unrecognized Loss 180 80% - 99% $ 3,327 606 80% - 99% $ 22,971 — 60% - 79% — 3 60% - 79% 1,888 — 40% - 59% — — 40% - 59% — — 20% - 39% — — 20% - 39% — — 0% - 19% — — 0% - 19% — $ 3,327 $ 24,859
Schedule of Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy	Other Investments September 30, 2016 December 31, 2015 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Alternative Investments Private equity $ 35,444 57,793 93,237 35,088 30,204 65,292 Private credit 27,709 30,763 58,472 13,246 15,129 28,375 Real assets 15,329 22,922 38,251 19,500 25,820 45,320 Total alternative investments 78,482 111,478 189,960 67,834 71,153 138,987 Other securities 10,030 22,611 32,641 10,008 3,200 13,208 Total other investments $ 88,512 134,089 222,601 77,842 74,353 152,195 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 June 30, Nine months ended June 30, ($ in millions) 2016 2015 2016 2015 Net investment (loss) income $ (55.4 ) 44.1 26.1 139.6 Realized gains 245.6 385.2 1,186.8 977.7 Net change in unrealized depreciation 117.8 (222.2 ) (1,132.8 ) (1,089.0 ) Net gain $ 308.0 207.1 80.1 28.3 Selective’s insurance subsidiaries’ other investments gain (loss) $ 1.6 1.3 — (0.8 )
Schedule of Securities Pledged As Collateral	($ in millions) FHLBI Collateral FHLBNY Collateral State and Regulatory Deposits Total U.S. government and government agencies $ 7.4 — 23.1 30.5 CMBS 1.0 — — 1.0 RMBS 53.1 64.4 — 117.5 Total pledged as collateral $ 61.5 64.4 23.1 149.0
Schedule of Net Investment Income Earned	Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Fixed income securities $ 32,453 30,601 $ 95,850 92,227 Equity securities 1,506 2,370 5,940 6,546 Short-term investments 192 24 493 72 Other investments 1,628 1,337 (49 ) (781 ) Investment expenses (2,404 ) (2,271 ) (6,908 ) (6,856 ) Net investment income earned $ 33,375 32,061 $ 95,326 91,208
Schedule of OTTI By Asset Type	Third Quarter 2016 Gross Included in Other Comprehensive Income ("OCI") Recognized in ($ in thousands) AFS equity securities: Common stock $ 342 — 342 Total AFS equity securities 342 — 342 Total OTTI losses $ 342 — 342 Third Quarter 2015 Gross Included in OCI Recognized in ($ in thousands) AFS fixed income securities: Corporate securities $ 253 — 253 Total AFS fixed income securities 253 — 253 AFS equity securities: Common stock 1,029 — 1,029 Total AFS equity securities 1,029 — 1,029 Total OTTI losses $ 1,282 — 1,282 Nine Months 2016 Gross Included in OCI Recognized in ($ in thousands) AFS fixed income securities: Corporate securities $ 1,077 — 1,077 RMBS 98 10 88 Total AFS fixed income securities 1,175 10 1,165 AFS equity securities: Common stock 3,316 — 3,316 Preferred stock 3 — 3 Total AFS equity securities 3,319 — 3,319 Total OTTI losses $ 4,494 10 4,484 Nine Months 2015 Gross Included in OCI Recognized in ($ in thousands) AFS fixed income securities: Corporate securities $ 1,445 — 1,445 RMBS 1 — 1 Total AFS fixed income securities 1,446 — 1,446 AFS equity securities: Common stock 6,201 — 6,201 Preferred stock 180 — 180 Total AFS equity securities 6,381 — 6,381 Total OTTI losses $ 7,827 — 7,827
Schedule of Components of Net Realized Gains Excluding OTTI Charges	Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 HTM fixed income securities Gains $ — 3 3 5 Losses — — (1 ) (1 ) AFS fixed income securities Gains 2,204 169 3,189 2,158 Losses (40 ) — (81 ) (130 ) AFS equity securities Gains 1,863 1,419 4,364 23,567 Losses — (1 ) (240 ) (1,347 ) Other investments Gains 3 — 3 — Losses — — (4 ) (654 ) Total net realized gains (excluding OTTI charges) $ 4,030 1,590 7,233 23,598
Held To Maturity Fixed Income Securities [Member]
Investments [Line Items]
Schedule of Fixed Maturity Securities By Contractual Maturities	($ in thousands) Carrying Value Fair Value Due in one year or less $ 59,074 59,671 Due after one year through five years 62,778 66,622 Due after five years through 10 years 8,620 9,801 Total HTM fixed income securities $ 130,472 136,094
AFS Fixed Income Securities [Member]
Investments [Line Items]
Schedule of Fixed Maturity Securities By Contractual Maturities	($ in thousands) Fair Value Due in one year or less $ 491,206 Due after one year through five years 2,403,246 Due after five years through 10 years 1,823,028 Due after 10 years 115,052 Total AFS fixed income securities $ 4,832,532

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Schedule of The Carrying Amounts and Estimated Fair Values of Financial Instruments	September 30, 2016 December 31, 2015 ($ in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial Assets Fixed income securities: HTM $ 130,472 136,094 201,354 209,544 AFS 4,832,532 4,832,532 4,408,203 4,408,203 Equity securities, AFS 147,304 147,304 207,051 207,051 Short-term investments 169,604 169,604 194,819 194,819 Financial Liabilities Short-term debt: 0.63% borrowings from FHLBI $ — — 15,000 14,977 1.25% borrowings from FHLBI 45,000 45,072 45,000 45,083 Total short-term debt $ 45,000 45,072 60,000 60,060 Long-term debt: 7.25% Senior Notes $ 49,900 60,682 49,898 56,929 6.70% Senior Notes 99,426 118,192 99,415 110,363 5.875% Senior Notes 185,000 194,324 185,000 192,474 1.61% borrowings from FHLBNY 25,000 25,048 — — 1.56% borrowings from FHLBNY 25,000 24,990 — — Subtotal long-term debt 384,326 423,236 334,313 359,766 Unamortized debt issuance costs (5,775 ) (6,121 ) Total long-term debt $ 378,551 328,192
Schedule of Quantitative Disclosures of Our Financial Assets That Were Measured At Fair Value	September 30, 2016 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 $ 89,891 35,147 54,744 — Foreign government 9,484 — 9,484 — Obligations of states and political subdivisions 1,446,896 — 1,446,896 — Corporate securities 2,196,118 — 2,196,118 — ABS 284,453 — 284,453 — CMBS 266,774 — 266,774 — RMBS 538,916 — 538,916 — Total AFS fixed income securities 4,832,532 35,147 4,797,385 — AFS equity securities: Common stock 135,489 127,813 — 7,676 Preferred stock 11,815 11,815 — — Total AFS equity securities 147,304 139,628 — 7,676 Total AFS securities 4,979,836 174,775 4,797,385 7,676 Short-term investments 169,604 169,604 — — Total assets measured at fair value $ 5,149,440 344,379 4,797,385 7,676 December 31, 2015 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 $ 104,115 42,702 61,413 — Foreign government 15,181 — 15,181 — Obligations of states and political subdivisions 1,359,142 — 1,359,142 — Corporate securities 1,900,182 — 1,900,182 — ABS 244,154 — 244,154 — CMBS 243,592 — 243,592 — RMBS 541,837 — 541,837 — Total AFS fixed income securities 4,408,203 42,702 4,365,501 — AFS equity securities: Common stock 194,789 191,517 — 3,272 Preferred stock 12,262 12,262 — — Total AFS equity securities 207,051 203,779 — 3,272 Total AFS securities 4,615,254 246,481 4,365,501 3,272 Short-term investments 194,819 194,819 — — Total assets measured at fair value $ 4,810,073 441,300 4,365,501 3,272 1 There were no transfers of securities between Level 1 and Level 2.
Schedule of Summary of the Changes in Fair Value of Securities Using Level 3 Inputs	September 30, 2016 Common Stock ($ in thousands) Fair value, December 31, 2015 $ 3,272 Total net (losses) gains for the period included in: OCI — Net income — Purchases 6,204 Sales (1,800 ) Issuances — Settlements — Transfers into Level 3 — Transfers out of Level 3 — Fair value, September 30, 2016 $ 7,676
Schedule of Quantitative Information of Our Financial Assets and Liabilities That Were Disclosed at Fair Value	September 30, 2016 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 $ 107,829 — 107,829 — Corporate securities 25,851 — 18,160 7,691 ABS 51 — 51 — CMBS 2,363 — 2,363 — Total HTM fixed income securities $ 136,094 — 128,403 7,691 Financial Liabilities Short-term debt: 1.25% borrowings from FHLBI $ 45,072 — 45,072 — Total short-term debt $ 45,072 — 45,072 — Long-term debt: 7.25% Senior Notes $ 60,682 — 60,682 — 6.70% Senior Notes 118,192 — 118,192 — 5.875% Senior Notes 194,324 194,324 — — 1.61% borrowings from FHLBNY 25,048 — 25,048 — 1.56% borrowings from FHLBNY 24,990 — 24,990 — Total long-term debt $ 423,236 194,324 228,912 — December 31, 2015 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 $ 181,880 — 181,880 — Corporate securities 22,015 — 18,679 3,336 ABS 1,028 — 1,028 — CMBS 4,621 — 4,621 — Total HTM fixed income securities $ 209,544 — 206,208 3,336 Financial Liabilities Short-term debt: 0.63% borrowings from FHLBI $ 14,977 — 14,977 — 1.25% borrowings from FHLBI 45,083 — 45,083 — Total short-term debt $ 60,060 — 60,060 — Long-term debt: 7.25% Senior Notes $ 56,929 — 56,929 — 6.70% Senior Notes 110,363 — 110,363 — 5.875% Senior Notes 192,474 192,474 — — Total long-term debt $ 359,766 192,474 167,292 —

Reinsurance (Tables)

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2016
Reinsurance Disclosures [Abstract]
Schedule of List Of Direct, Assumed, And Ceded Reinsurance Amounts	Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Premiums written: Direct $ 669,844 631,429 $ 1,981,984 1,851,620 Assumed 7,644 6,099 21,752 17,140 Ceded (98,715 ) (92,503 ) (281,464 ) (273,514 ) Net $ 578,773 545,025 $ 1,722,272 1,595,246 Premiums earned: Direct $ 627,520 590,716 $ 1,846,587 1,728,865 Assumed 7,163 5,830 20,604 16,831 Ceded (92,254 ) (89,156 ) (270,372 ) (271,874 ) Net $ 542,429 507,390 $ 1,596,819 1,473,822 Loss and loss expense incurred: Direct $ 428,520 306,635 $ 1,152,223 935,529 Assumed 5,929 4,224 18,424 13,114 Ceded (118,191 ) (25,698 ) (258,766 ) (86,922 ) Net $ 316,258 285,161 $ 911,881 861,721
Schedule of Ceded Premiums and Losses Related to Flood Operations	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) 2016 2015 2016 2015 Ceded premiums written $ (62,051 ) (62,463 ) $ (179,205 ) (178,784 ) Ceded premiums earned (56,505 ) (58,340 ) (169,986 ) (176,119 ) Ceded loss and loss expense incurred (99,200 ) (15,382 ) (164,179 ) (36,315 )

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Schedule of Revenue By Segment	Revenue by Segment Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Standard Commercial Lines: Net premiums earned: Commercial automobile $ 100,612 90,758 294,927 265,771 Workers compensation 78,596 74,560 229,847 213,991 General liability 133,981 123,252 391,349 357,430 Commercial property 74,052 68,587 217,821 199,699 Businessowners’ policies 24,461 23,726 73,016 69,603 Bonds 5,795 5,031 16,924 15,137 Other 4,089 3,628 11,868 10,649 Miscellaneous income 1,925 448 6,182 4,680 Total Standard Commercial Lines revenue 423,511 389,990 1,241,934 1,136,960 Standard Personal Lines: Net premiums earned: Personal automobile 34,865 36,623 106,526 110,373 Homeowners 32,031 33,670 98,342 101,122 Other 1,794 1,795 4,851 5,143 Miscellaneous income 275 250 836 841 Total Standard Personal Lines revenue 68,965 72,338 210,555 217,479 E&S Lines: Net premiums earned: General liability 37,398 32,395 108,372 87,914 Commercial property 11,853 11,309 35,013 31,428 Commercial automobile 2,902 2,056 7,963 5,562 Miscellaneous income (1 ) — — — Total E&S Lines revenue 52,152 45,760 151,348 124,904 Investments: Net investment income 33,375 32,061 95,326 91,208 Net realized investment gains 3,688 308 2,749 15,771 Total Investments revenue 37,063 32,369 98,075 106,979 Total revenues $ 581,691 540,457 1,701,912 1,586,322 Income Before Federal Income Tax Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Standard Commercial Lines: Underwriting gain $ 30,124 44,027 101,229 109,304 GAAP combined ratio 92.9 % 88.7 91.8 90.3 Statutory combined ratio 92.0 88.4 90.1 89.4 Standard Personal Lines: Underwriting gain (loss) $ 4,271 2,826 19,001 (4,295 ) GAAP combined ratio 93.8 % 96.1 90.9 102.0 Statutory combined ratio 92.0 95.0 90.7 101.7 E&S Insurance Operations: Underwriting loss $ (2,362 ) (2,022 ) (3,465 ) (5,033 ) GAAP combined ratio 104.5 % 104.4 102.3 104.0 Statutory combined ratio 101.4 101.1 100.9 101.8 Investments: Net investment income $ 33,375 32,061 95,326 91,208 Net realized investment gains 3,688 308 2,749 15,771 Total investment income, before federal income tax 37,063 32,369 98,075 106,979 Tax on investment income 9,752 7,614 24,290 26,186 Total investment income, after federal income tax $ 27,311 24,755 73,785 80,793
Schedule of Income Before Federal Income Tax	Income Before Federal Income Tax Quarter ended September 30, Nine Months ended September 30, ($ in thousands) 2016 2015 2016 2015 Standard Commercial Lines: Underwriting gain $ 30,124 44,027 101,229 109,304 GAAP combined ratio 92.9 % 88.7 91.8 90.3 Statutory combined ratio 92.0 88.4 90.1 89.4 Standard Personal Lines: Underwriting gain (loss) $ 4,271 2,826 19,001 (4,295 ) GAAP combined ratio 93.8 % 96.1 90.9 102.0 Statutory combined ratio 92.0 95.0 90.7 101.7 E&S Insurance Operations: Underwriting loss $ (2,362 ) (2,022 ) (3,465 ) (5,033 ) GAAP combined ratio 104.5 % 104.4 102.3 104.0 Statutory combined ratio 101.4 101.1 100.9 101.8 Investments: Net investment income $ 33,375 32,061 95,326 91,208 Net realized investment gains 3,688 308 2,749 15,771 Total investment income, before federal income tax 37,063 32,369 98,075 106,979 Tax on investment income 9,752 7,614 24,290 26,186 Total investment income, after federal income tax $ 27,311 24,755 73,785 80,793
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) 2016 2015 2016 2015 Underwriting gain (loss), before federal income tax Standard Commercial Lines $ 30,124 44,027 101,229 109,304 Standard Personal Lines 4,271 2,826 19,001 (4,295 ) E&S Lines (2,362 ) (2,022 ) (3,465 ) (5,033 ) Investment income, before federal income tax 37,063 32,369 98,075 106,979 Total all segments 69,096 77,200 214,840 206,955 Interest expense (5,714 ) (5,610 ) (16,940 ) (16,826 ) General corporate and other expenses (7,939 ) (5,751 ) (28,271 ) (21,235 ) Income before federal income tax $ 55,443 65,839 169,629 168,894

Retirement Plans (Table)

Retirement Plans (Table)	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Schedule of Components of Net Periodic Benefit Cost	Pension Plan Pension Plan ($ in thousands) 2016 2015 2016 2015 Net Periodic Benefit Cost: Service cost $ 41 1,913 1,647 5,738 Interest cost 3,049 3,409 9,252 10,225 Expected return on plan assets (5,006 ) (3,991 ) (12,982 ) (11,972 ) Amortization of unrecognized net actuarial loss 1,763 1,643 4,724 4,930 Total net periodic cost $ (153 ) 2,974 2,641 8,921 As of December 31, 2015, we anticipated contributing $11.7 million to the Pension Plan for full year 2016. Actual contributions amounted to $54.5 million in Nine Months 2016 and we do not anticipate any additional funding this year. The decrease in net periodic cost in Third Quarter 2016 reflects lower expense as a result of the contributions that were higher than our original expectation. Pension Plan 2016 2015 Weighted-Average Expense Assumptions: Discount rate 4.69 % 4.29 % Effective interest rate for calculation of service cost 4.89 % — % Effective interest rate for calculation of interest cost 4.02 % — % Expected return on plan assets 6.37 % 6.27 % Rate of compensation increase 1 n/a 4.00 %
Schedule of Weighted-Average Expense Assumptions	Pension Plan 2016 2015 Weighted-Average Expense Assumptions: Discount rate 4.69 % 4.29 % Effective interest rate for calculation of service cost 4.89 % — % Effective interest rate for calculation of interest cost 4.02 % — % Expected return on plan assets 6.37 % 6.27 % Rate of compensation increase 1 n/a 4.00 % 1 This assumption was 4.0% through March 31, 2016, the date after which benefits ceased accruing for all participants of the Pension Plan.

Comprehensive Income (Tables)

Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2016
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Schedule of Components of Comprehensive Income-Gross and Net of Tax	Third Quarter 2016 ($ in thousands) Gross Tax Net Net income $ 55,443 16,941 38,502 Components of OCI: Unrealized losses on investment securities : Unrealized holding losses during period (12,992 ) (4,548 ) (8,444 ) Amounts reclassified into net income: HTM securities (13 ) (4 ) (9 ) Realized gains on AFS securities (3,684 ) (1,289 ) (2,395 ) Total unrealized losses on investment securities (16,689 ) (5,841 ) (10,848 ) Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,615 565 1,050 Total defined benefit pension and post-retirement plans 1,615 565 1,050 Other comprehensive loss (15,074 ) (5,276 ) (9,798 ) Comprehensive income $ 40,369 11,665 28,704 Third Quarter 2015 ($ in thousands) Gross Tax Net Net income $ 65,839 18,843 46,996 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 8,371 2,929 5,442 Amounts reclassified into net income: HTM securities (97 ) (34 ) (63 ) Realized gains on AFS securities (305 ) (106 ) (199 ) Total unrealized gains on investment securities 7,969 2,789 5,180 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,709 599 1,110 Total defined benefit pension and post-retirement plans 1,709 599 1,110 Other comprehensive income 9,678 3,388 6,290 Comprehensive income $ 75,517 22,231 53,286 Nine Months 2016 ($ in thousands) Gross Tax Net Net income $ 169,629 50,494 119,135 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 108,420 37,947 70,473 Non-credit portion of OTTI recognized in OCI (10 ) (4 ) (6 ) Amounts reclassified into net income: HTM securities (104 ) (36 ) (68 ) Realized gains on AFS securities (2,747 ) (961 ) (1,786 ) Total unrealized gains on investment securities 105,559 36,946 68,613 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 4,648 1,627 3,021 Total defined benefit pension and post-retirement plans 4,648 1,627 3,021 Other comprehensive income 110,207 38,573 71,634 Comprehensive income $ 279,836 89,067 190,769 Nine Months 2015 ($ in thousands) Gross Tax Net Net income $ 168,894 48,422 120,472 Components of OCI: Unrealized losses on investment securities : Unrealized holding losses during period (27,896 ) (9,764 ) (18,132 ) Amounts reclassified into net income: HTM securities (543 ) (190 ) (353 ) Non-credit OTTI 357 125 232 Realized gains on AFS securities (16,778 ) (5,872 ) (10,906 ) Total unrealized losses on investment securities (44,860 ) (15,701 ) (29,159 ) Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 5,127 1,795 3,332 Total defined benefit pension and post-retirement plans 5,127 1,795 3,332 Other comprehensive loss (39,733 ) (13,906 ) (25,827 ) Comprehensive income $ 129,161 34,516 94,645
Schedule of Components of Accumulated Other Comprehensive Income	September 30, 2016 Defined Benefit Pension and Post-Retirement Plans Net Unrealized Gain on Investment Securities Total AOCI ($ in thousands) OTTI Related HTM Related All Other Investments Subtotal Balance, December 31, 2015 $ (282 ) 194 45,083 44,995 (54,420 ) (9,425 ) OCI before reclassifications (6 ) — 70,473 70,467 — 70,467 Amounts reclassified from AOCI — (68 ) (1,786 ) (1,854 ) 3,021 1,167 Net current period OCI (6 ) (68 ) 68,687 68,613 3,021 71,634 Balance, September 30, 2016 $ (288 ) 126 113,770 113,608 (51,399 ) 62,209
Schedule of Reclassifications Out Of Accumulated Other Comprehensive Income	Quarter ended Nine Months ended Affected Line Item in the Unaudited Consolidated Statement of Income ($ in thousands) 2016 2015 2016 2015 OTTI related Non-credit OTTI on disposed securities $ — — — 357 Net realized gains — — — 357 Income before federal income tax — — — (125 ) Total federal income tax expense — — — 232 Net income HTM related Unrealized losses on HTM disposals 73 121 161 258 Net realized gains Amortization of net unrealized gains on HTM securities (86 ) (218 ) (265 ) (801 ) Net investment income earned (13 ) (97 ) (104 ) (543 ) Income before federal income tax 4 34 36 190 Total federal income tax expense (9 ) (63 ) (68 ) (353 ) Net income Realized losses (gains) on AFS and OTTI Realized losses (gains) on AFS disposals and OTTI (3,684 ) (305 ) (2,747 ) (16,778 ) Net realized gains (3,684 ) (305 ) (2,747 ) (16,778 ) Income before federal income tax 1,289 106 961 5,872 Total federal income tax expense (2,395 ) (199 ) (1,786 ) (10,906 ) Net income Defined benefit pension and post-retirement life plans Net actuarial loss 351 371 1,009 1,114 Loss and loss expense incurred 1,264 1,338 3,639 4,013 Policy acquisition costs Total defined benefit pension and post-retirement life 1,615 1,709 4,648 5,127 Income before federal income tax (565 ) (599 ) (1,627 ) (1,795 ) Total federal income tax expense 1,050 1,110 3,021 3,332 Net income Total reclassifications for the period $ (1,354 ) 848 1,167 (7,695 ) Net income

Statements of Cash Flow (Cash F

Statements of Cash Flow (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015
Interest		$ 13,874	$ 13,843
Federal income tax		36,405	18,500
Corporate actions related to equity securities, AFS	[1]	3,032	4,239
Assets acquired under capital lease arrangements		3,108	6,933
Non-cash purchase of property and equipment		648	0
AFS Fixed Maturity Securities [Member]
Exchange of fixed income securities		21,775	35,425
Held-to-maturity Securities [Member]
Exchange of fixed income securities		0	10,045
National Flood Insurance Program [Member]
Restricted cash		$ 20,900	$ 9,900
[1]	Examples of such corporate actions include non-cash acquisitions and stock splits.

Investments (Held-To-Maturity S

Investments (Held-To-Maturity Securities Disclosure) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 130,278	$ 201,054
Net Unrealized Gains (Losses)	194	300
Carrying Value	130,472	201,354
Unrecognized Holding Gains	5,622	8,190
Unrecognized Holding Losses	0	0
Held-to-maturity Securities, Fair Value	$ 136,094	209,544
Held-to-maturity Securities Average Duration	1 year 7 months
Obligations of States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 104,159	175,269
Net Unrealized Gains (Losses)	414	848
Carrying Value	104,573	176,117
Unrecognized Holding Gains	3,256	5,763
Unrecognized Holding Losses	0	0
Held-to-maturity Securities, Fair Value	107,829	181,880
Corporate Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	23,722	20,228
Net Unrealized Gains (Losses)	(165)	(185)
Carrying Value	23,557	20,043
Unrecognized Holding Gains	2,294	1,972
Unrecognized Holding Losses	0	0
Held-to-maturity Securities, Fair Value	25,851	22,015
Asset-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	51	1,030
Net Unrealized Gains (Losses)	0	(120)
Carrying Value	51	910
Unrecognized Holding Gains	0	118
Unrecognized Holding Losses	0	0
Held-to-maturity Securities, Fair Value	51	1,028
Commercial Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	2,346	4,527
Net Unrealized Gains (Losses)	(55)	(243)
Carrying Value	2,291	4,284
Unrecognized Holding Gains	72	337
Unrecognized Holding Losses	0	0
Held-to-maturity Securities, Fair Value	$ 2,363	$ 4,621

Investments (Available-For-Sale

Investments (Available-For-Sale Securities Disclosure) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	$ 4,805,248	$ 4,546,330
Unrealized Gains	177,915	93,777
Unrealized Losses	(3,327)	(24,853)
Total AFS securities	4,979,836	4,615,254
AFS Fixed Income Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	4,682,267	4,352,514
Unrealized Gains	152,503	78,504
Unrealized Losses	(2,238)	(22,815)
Total AFS securities	4,832,532	4,408,203
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	86,491	99,485
Unrealized Gains	3,400	4,721
Unrealized Losses	0	(91)
Total AFS securities	89,891	104,115
AFS Fixed Income Securities [Member] | Foreign Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	9,041	14,885
Unrealized Gains	443	298
Unrealized Losses	0	(2)
Total AFS securities	9,484	15,181
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	1,376,245	1,314,779
Unrealized Gains	70,984	44,523
Unrealized Losses	(333)	(160)
Total AFS securities	1,446,896	1,359,142
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	2,136,761	1,892,296
Unrealized Gains	60,784	23,407
Unrealized Losses	(1,427)	(15,521)
Total AFS securities	2,196,118	1,900,182
AFS Fixed Income Securities [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	282,558	244,541
Unrealized Gains	1,964	531
Unrealized Losses	(69)	(918)
Total AFS securities	284,453	244,154
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	261,233	245,252
Unrealized Gains	5,634	750
Unrealized Losses	(93)	(2,410)
Total AFS securities	266,774	243,592
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	529,938	541,276
Unrealized Gains	9,294	4,274
Unrealized Losses	(316)	(3,713)
Total AFS securities	538,916	541,837
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	122,981	193,816
Unrealized Gains	25,412	15,273
Unrealized Losses	(1,089)	(2,038)
Total AFS securities	147,304	207,051
Equity Securities [Member] | Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	111,746	181,991
Unrealized Gains	24,832	14,796
Unrealized Losses	(1,089)	(1,998)
Total AFS securities	135,489	194,789
Equity Securities [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	11,235	11,825
Unrealized Gains	580	477
Unrealized Losses	0	(40)
Total AFS securities	$ 11,815	$ 12,262

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, 2016	Dec. 31, 2015
AFS Fair Value, Less than 12 months		$ 303,470	$ 1,449,183
AFS Unrealized Losses, Less than 12 months	[1]	(2,726)	(19,953)
AFS Fair Value, 12 months or longer		79,305	141,580
AFS Unrealized Losses, 12 months or longer	[1]	(601)	(4,900)
AFS Fixed Income Securities [Member]
AFS Fair Value, Less than 12 months		290,942	1,416,504
AFS Unrealized Losses, Less than 12 months	[1]	(1,637)	(17,915)
AFS Fair Value, 12 months or longer		79,305	141,580
AFS Unrealized Losses, 12 months or longer	[1]	(601)	(4,900)
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member]
AFS Fair Value, Less than 12 months			16,006
AFS Unrealized Losses, Less than 12 months	[1]		(87)
AFS Fair Value, 12 months or longer			396
AFS Unrealized Losses, 12 months or longer	[1]		(4)
AFS Fixed Income Securities [Member] | Foreign Government [Member]
AFS Fair Value, Less than 12 months			1,067
AFS Unrealized Losses, Less than 12 months	[1]		(2)
AFS Fair Value, 12 months or longer			0
AFS Unrealized Losses, 12 months or longer	[1]		0
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
AFS Fair Value, Less than 12 months		74,989	28,617
AFS Unrealized Losses, Less than 12 months	[1]	(333)	(160)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
AFS Fair Value, Less than 12 months		155,880	761,479
AFS Unrealized Losses, Less than 12 months	[1]	(1,139)	(12,671)
AFS Fair Value, 12 months or longer		30,469	50,382
AFS Unrealized Losses, 12 months or longer	[1]	(288)	(2,850)
AFS Fixed Income Securities [Member] | Asset-Backed Securities [Member]
AFS Fair Value, Less than 12 months		21,766	197,477
AFS Unrealized Losses, Less than 12 months	[1]	(66)	(807)
AFS Fair Value, 12 months or longer		2,450	12,022
AFS Unrealized Losses, 12 months or longer	[1]	(3)	(111)
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
AFS Fair Value, Less than 12 months		24,633	146,944
AFS Unrealized Losses, Less than 12 months	[1]	(59)	(2,196)
AFS Fair Value, 12 months or longer		8,709	15,385
AFS Unrealized Losses, 12 months or longer	[1]	(34)	(214)
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
AFS Fair Value, Less than 12 months		13,674	264,914
AFS Unrealized Losses, Less than 12 months	[1]	(40)	(1,992)
AFS Fair Value, 12 months or longer		37,677	63,395
AFS Unrealized Losses, 12 months or longer	[1]	(276)	(1,721)
Equity Securities [Member]
AFS Fair Value, Less than 12 months		12,528	32,679
AFS Unrealized Losses, Less than 12 months	[1]	(1,089)	(2,038)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
Equity Securities [Member] | Common Stock [Member]
AFS Fair Value, Less than 12 months		12,528	31,148
AFS Unrealized Losses, Less than 12 months	[1]	(1,089)	(1,998)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	$ 0	0
Equity Securities [Member] | Preferred Stock [Member]
AFS Fair Value, Less than 12 months			1,531
AFS Unrealized Losses, Less than 12 months	[1]		(40)
AFS Fair Value, 12 months or longer			0
AFS Unrealized Losses, 12 months or longer	[1]		$ 0
[1]	Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI.

Investments (Number of Securiti

Investments (Number of Securities in an Unrealized Unrecognized Loss Position) (Details) $ in Thousands	Sep. 30, 2016USD ($)Securities	Dec. 31, 2015USD ($)Securities
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Unrealized Unrecognized Loss	$ 3,327	$ 24,859
Eighty Percent to Ninety-Nine Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	180	606
Unrealized Unrecognized Loss	$ 3,327	$ 22,971
Sixty Percent to Seventy-Nine Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	0	3
Unrealized Unrecognized Loss	$ 0	$ 1,888
Forty Percent to Fifty-Nine Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	0	0
Unrealized Unrecognized Loss	$ 0	$ 0
Twenty Percent to Thirty-Nine Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	0	0
Unrealized Unrecognized Loss	$ 0	$ 0
Zero Percent to Nineteen Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	0	0
Unrealized Unrecognized Loss	$ 0	$ 0

Investments (HTM Fixed Income S

Investments (HTM Fixed Income Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less carrying value	$ 59,074
Due after one year through five years carrying value	62,778
Due after five years through 10 years carrying value	8,620
Carrying Value	130,472	$ 201,354
Due in one year or less fair value	59,671
Due after one year through five years fair value	66,622
Due after five years through 10 years fair value	9,801
HTM, Fair Value	$ 136,094	$ 209,544

Investments (AFS Fixed Income s

Investments (AFS Fixed Income securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less fair value	$ 491,206
Due after one year through five years fair value	2,403,246
Due after five years through 10 years fair value	1,823,028
Due after 10 years fair value	115,052
Total AFS fixed income securities	$ 4,832,532	$ 4,408,203

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, 2016	Dec. 31, 2015
Carrying Value		$ 88,512	$ 77,842
Other Investments [Member]
Carrying Value		88,512	77,842
Remaining Commitment		134,089	74,353
Maximum Exposure to Loss	[1]	222,601	152,195
Alternative Investments [Member]
Carrying Value		78,482	67,834
Remaining Commitment		111,478	71,153
Maximum Exposure to Loss	[1]	189,960	138,987
Private Equity [Member] | Alternative Investments [Member]
Carrying Value		35,444	35,088
Remaining Commitment		57,793	30,204
Maximum Exposure to Loss	[1]	93,237	65,292
Private Credit [Member] | Alternative Investments [Member]
Carrying Value		27,709	13,246
Remaining Commitment		30,763	15,129
Maximum Exposure to Loss	[1]	58,472	28,375
Real Assets [Member] | Alternative Investments [Member]
Carrying Value		15,329	19,500
Remaining Commitment		22,922	25,820
Maximum Exposure to Loss	[1]	38,251	45,320
Other Securities [Member]
Carrying Value		10,030	10,008
Remaining Commitment		22,611	3,200
Maximum Exposure to Loss	[1]	$ 32,641	$ 13,208
[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, 2016	Jun. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2015	Jun. 30, 2015
Schedule of Equity Method Investments [Line Items]
Net investment income earned	$ 33,375		$ 32,061		$ 95,326		$ 91,208
Alternative Investments [Member]
Schedule of Equity Method Investments [Line Items]
Net investment income earned	$ 1,600		$ 1,300		$ 0		$ (800)
Investments accounted for under the equity method [Member]
Schedule of Equity Method Investments [Line Items]
Net investment (loss) income		$ (55,400)		$ 44,100		$ 26,100		$ 139,600
Realized gains		245,600		385,200		1,186,800		977,700
Net change in unrealized depreciation		117,800		(222,200)		(1,132,800)		(1,089,000)
Net gain		$ 308,000		$ 207,100		$ 80,100		$ 28,300

Investments (Investments Pledge

Investments (Investments Pledged as Collateral) (Details) $ in Millions	Sep. 30, 2016USD ($)
Investments Pledged As Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	$ 23.1
Securities Pledged As Collateral	149
U.S. Government and Government Agencies [Member]
Investments Pledged As Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	23.1
Securities Pledged As Collateral	30.5
Commercial Mortgage Backed Securities [Member]
Investments Pledged As Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	0
Securities Pledged As Collateral	1
Residential Mortgage Backed Securities [Member]
Investments Pledged As Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	0
Securities Pledged As Collateral	117.5
Federal Home Loan Bank of Indianapolis [Member]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	61.5
Federal Home Loan Bank of Indianapolis [Member] | U.S. Government and Government Agencies [Member]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	7.4
Federal Home Loan Bank of Indianapolis [Member] | Commercial Mortgage Backed Securities [Member]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	1
Federal Home Loan Bank of Indianapolis [Member] | Residential Mortgage Backed Securities [Member]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	53.1
Federal Home Loan Bank of New York [Member]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	64.4
Federal Home Loan Bank of New York [Member] | U.S. Government and Government Agencies [Member]
Investments 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]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	0
Federal Home Loan Bank of New York [Member] | Residential Mortgage Backed Securities [Member]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	$ 64.4

Investments (Credit Concentrati

Investments (Credit Concentration Risk) (Details)	Sep. 30, 2016	Dec. 31, 2015
Investments [Abstract]
Maximum exposure to credit concentration risk of the Company's stockholder's equity other than certain U.S. government agencies	10.00%	10.00%

Investments (Net Investment Inc

Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Investment Income [Line Items]
Net investment income earned	$ 33,375	$ 32,061	$ 95,326	$ 91,208
Fixed Income Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	32,453	30,601	95,850	92,227
Equity Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	1,506	2,370	5,940	6,546
Short-Term Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	192	24	493	72
Other Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	1,628	1,337	(49)	(781)
Investment Expenses [Member]
Net Investment Income [Line Items]
Net investment income earned	$ (2,404)	$ (2,271)	$ (6,908)	$ (6,856)

Investments (OTTI by Asset Type

Investments (OTTI by Asset Type) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
OTTI Losses Gross	$ 342	$ 1,282	$ 4,494	$ 7,827
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0	10	0
OTTI Losses Recognized in Earnings	342	1,282	4,484	7,827
AFS Fixed Income Securities [Member]
OTTI Losses Gross		253	1,175	1,446
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income		0	10	0
OTTI Losses Recognized in Earnings		253	1,165	1,446
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
OTTI Losses Gross		253	1,077	1,445
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income		0	0	0
OTTI Losses Recognized in Earnings		253	1,077	1,445
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
OTTI Losses Gross			98	1
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income			10	0
OTTI Losses Recognized in Earnings			88	1
Total AFS Securities [Member] | Equity Securities [Member]
OTTI Losses Gross	342	1,029	3,319	6,381
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0	0	0
OTTI Losses Recognized in Earnings	342	1,029	3,319	6,381
Common Stock [Member] | Total AFS Securities [Member] | Equity Securities [Member]
OTTI Losses Gross	342	1,029	3,316	6,201
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0	0	0
OTTI Losses Recognized in Earnings	$ 342	$ 1,029	3,316	6,201
Preferred Stock [Member] | Total AFS Securities [Member] | Equity Securities [Member]
OTTI Losses Gross			3	180
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income			0	0
OTTI Losses Recognized in Earnings			$ 3	$ 180

Investments (Components Of Net

Investments (Components Of Net Realized Gains, Excluding OTTI Charges) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
HTM securities realized gain	$ 0	$ 3	$ 3	$ 5
HTM fixed income securities losses	0	0	(1)	(1)
Other investments gains	3	0	3	0
Other investments losses	0	0	(4)	(654)
Total net realized gains (excluding OTTI charges)	4,030	1,590	7,233	23,598
Proceeds from sale of available for sale securities	27,000	12,700	132,900	170,600
Fixed Income Securities [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
AFS securities gains	2,204	169	3,189	2,158
AFS securities losses	(40)	0	(81)	(130)
Equity Securities [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
AFS securities gains	1,863	1,419	4,364	23,567
AFS securities losses	$ 0	$ (1)	$ (240)	$ (1,347)

Indebtedness (Details)

Indebtedness (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Debt Instruments [Line Items]
Repayments of Federal Home Loan Bank Borrowings	$ 70,000	$ 0
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Debt Instruments [Line Items]
Outstanding Borrowing With The Federal Home Loan Bank Of New York	$ 25,000
Unpaid principal amount interest rate	1.61%
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Debt Instruments [Line Items]
Outstanding Borrowing With The Federal Home Loan Bank Of New York	$ 25,000
Unpaid principal amount interest rate	1.56%
Zero Point Fifty Nine Percent Borrowing From Federal Home Loan Bank Due March 18, 2016 [Member]
Debt Instruments [Line Items]
Outstanding Borrowing With The Federal Home Loan Bank Of New York	$ 25,000
Unpaid principal amount interest rate	0.59%
Zero Point Fifty Two Percent Borrowing From Federal Home Loan Bank Due April 28, 2016 [Member]
Debt Instruments [Line Items]
Outstanding Borrowing With The Federal Home Loan Bank Of New York	$ 15,000
Unpaid principal amount interest rate	0.52%
Zero Point Fifty Three Percent Borrowing From Federal Home Loan Bank Due May 19, 2016 [Member]
Debt Instruments [Line Items]
Outstanding Borrowing With The Federal Home Loan Bank Of New York	$ 15,000
Unpaid principal amount interest rate	0.53%
Federal Home Loan Bank of Indianapolis [Member]
Debt Instruments [Line Items]
Repayments of Federal Home Loan Bank Borrowings	$ 15,000

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Value and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Held-to-maturity securities	$ 130,472	$ 201,354
Available-for-sale securities	4,832,532	4,408,203
Equity securities, AFS	147,304	207,051
Short-term investments	169,604	194,819
Short-term debt	45,000	60,000
Long-term debt	378,551	328,192
Seven Point Twenty Five Percent Senior Notes [Member]
Long-term debt	60,682	56,929
Six Point Seventy Percent Senior Notes [Member]
Long-term debt	118,192	110,363
Five Point Eight Hundred Seventy Five Senior Notes [Member]
Long-term debt	194,324	192,474
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term debt	25,048
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term debt	24,990
Zero Point Sixty Three Percent Borrowing From Federal Home Loan Bank Due July 22, 2016 [Member]
Short-term debt		14,977
One Point Twenty Five Percent Borrowing From Federal Home Loan Bank [Member]
Short-term debt	45,072	45,083
Reported Value Measurement [Member]
Held-to-maturity securities	130,472	201,354
Available-for-sale securities	4,832,532	4,408,203
Equity securities, AFS	147,304	207,051
Short-term investments	169,604	194,819
Short-term debt	45,000	60,000
Long-term debt	378,551	328,192
Reported Value Measurement [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Long-term debt	49,900	49,898
Reported Value Measurement [Member] | Six Point Seventy Percent Senior Notes [Member]
Long-term debt	99,426	99,415
Reported Value Measurement [Member] | Five Point Eight Hundred Seventy Five Senior Notes [Member]
Long-term debt	185,000	185,000
Reported Value Measurement [Member] | One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term debt	25,000	0
Reported Value Measurement [Member] | One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term debt	25,000	0
Reported Value Measurement [Member] | Long Term Debt Excluding Issuance Costs [Member]
Long-term debt	384,326	334,313
Reported Value Measurement [Member] | Unamortized Debt Issuance Costs [Member]
Unamortized debt issuance costs	(5,775)	(6,121)
Reported Value Measurement [Member] | Zero Point Sixty Three Percent Borrowing From Federal Home Loan Bank Due July 22, 2016 [Member]
Short-term debt	0	15,000
Reported Value Measurement [Member] | One Point Twenty Five Percent Borrowing From Federal Home Loan Bank [Member]
Short-term debt	45,000	45,000
Estimate of Fair Value Measurement [Member]
Held-to-maturity securities	136,094	209,544
Available-for-sale securities	4,832,532	4,408,203
Equity securities, AFS	147,304	207,051
Short-term investments	169,604	194,819
Short-term debt	45,072	60,060
Long-term debt	423,236	359,766
Estimate of Fair Value Measurement [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Long-term debt	60,682	56,929
Estimate of Fair Value Measurement [Member] | Six Point Seventy Percent Senior Notes [Member]
Long-term debt	118,192	110,363
Estimate of Fair Value Measurement [Member] | Five Point Eight Hundred Seventy Five Senior Notes [Member]
Long-term debt	194,324	192,474
Estimate of Fair Value Measurement [Member] | One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Long-term debt	25,048	0
Estimate of Fair Value Measurement [Member] | One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Long-term debt	24,990	0
Estimate of Fair Value Measurement [Member] | Zero Point Sixty Three Percent Borrowing From Federal Home Loan Bank Due July 22, 2016 [Member]
Short-term debt	0	14,977
Estimate of Fair Value Measurement [Member] | One Point Twenty Five Percent Borrowing From Federal Home Loan Bank [Member]
Short-term debt	$ 45,072	$ 45,083

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Disclosures of Fair Value Assets) (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Available-for-sale Securities, Debt Securities		$ 4,832,532	$ 4,408,203
Equity securities, AFS		147,304	207,051
Total AFS securities		4,979,836	4,615,254
Short-term investments		169,604	194,819
Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		4,832,532	4,408,203
Equity securities, AFS		147,304	207,051
Total AFS securities		4,979,836	4,615,254
Short-term investments		169,604	194,819
Total assets measured at fair value		5,149,440	4,810,073
U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		89,891	104,115
Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		9,484	15,181
Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		1,446,896	1,359,142
Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		2,196,118	1,900,182
Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		284,453	244,154
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		266,774	243,592
Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		538,916	541,837
Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS		135,489	194,789
Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS		11,815	12,262
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	35,147	42,702
Equity securities, AFS	[1]	139,628	203,779
Total AFS securities	[1]	174,775	246,481
Short-term investments	[1]	169,604	194,819
Total assets measured at fair value	[1]	344,379	441,300
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, Debt Securities	[1]	35,147	42,702
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	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, Debt Securities	[1]	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, Debt Securities	[1]	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	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, Debt Securities	[1]	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, Debt Securities	[1]	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS	[1]	127,813	191,517
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS	[1]	11,815	12,262
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	4,797,385	4,365,501
Equity securities, AFS	[1]	0	0
Total AFS securities	[1]	4,797,385	4,365,501
Short-term investments	[1]	0	0
Total assets measured at fair value	[1]	4,797,385	4,365,501
Significant Other Observable Inputs (Level 2) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	54,744	61,413
Significant Other Observable Inputs (Level 2) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	9,484	15,181
Significant Other Observable Inputs (Level 2) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	1,446,896	1,359,142
Significant Other Observable Inputs (Level 2) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	2,196,118	1,900,182
Significant Other Observable Inputs (Level 2) [Member] | Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	284,453	244,154
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	266,774	243,592
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	538,916	541,837
Significant Other Observable Inputs (Level 2) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS	[1]	0	0
Significant Other Observable Inputs (Level 2) [Member] | Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS	[1]	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		0	0
Equity securities, AFS		7,676	3,272
Total AFS securities		7,676	3,272
Short-term investments		0	0
Total assets measured at fair value		7,676	3,272
Significant Unobservable Inputs (Level 3) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt 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, Debt Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS		7,676	3,272
Significant Unobservable Inputs (Level 3) [Member] | Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS		$ 0	$ 0
[1]	1 There were no transfers of securities between Level 1 and Level 2.

Fair Value Measurements (Change

Fair Value Measurements (Changes in Fair Value of Securities Using Level 3 Inputs) (Details) - Common Stock [Member] - AFS Fixed Maturity Securities [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2016USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, December 31, 2015	$ 3,272
Total net (losses) gains for the period included in other comprehensive income	0
Total net (losses) gains for the period included in net income	0
Purchases	6,204
Sales	(1,800)
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	0
Fair Value, September 30, 2016	$ 7,676

Fair Value Measurements (Quan46

Fair Value Measurements (Quantitative Information of Our Financial Assets and Liabilities That Were Disclosed at Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	$ 136,094	$ 209,544
Short-term debt	45,000	60,000
Long-term debt	378,551	328,192
Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	60,682	56,929
Six Point Seventy Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	118,192	110,363
Five Point Eight Hundred Seventy Five Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	194,324	192,474
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	25,048
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	24,990
Long-term Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	423,236	359,766
Zero Point Sixty Three Percent Borrowing From Federal Home Loan Bank Due July 22, 2016 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt		14,977
One Point Twenty Five Percent Borrowing From Federal Home Loan Bank [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt	45,072	45,083
Short-term Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt	45,072	60,060
Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	107,829	181,880
Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	25,851	22,015
Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	51	1,028
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	2,363	4,621
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Short-term debt	0	0
Long-term debt	194,324	192,474
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Six Point Seventy Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	194,324	192,474
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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Zero Point Sixty Three Percent Borrowing From Federal Home Loan Bank Due July 22, 2016 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt		0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | One Point Twenty Five Percent Borrowing From Federal Home Loan Bank [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	128,403	206,208
Short-term debt	45,072	60,060
Long-term debt	228,912	167,292
Significant Other Observable Inputs (Level 2) [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	60,682	56,929
Significant Other Observable Inputs (Level 2) [Member] | Six Point Seventy Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	118,192	110,363
Significant Other Observable Inputs (Level 2) [Member] | Five Point Eight Hundred Seventy Five Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	25,048
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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	24,990
Significant Other Observable Inputs (Level 2) [Member] | Zero Point Sixty Three Percent Borrowing From Federal Home Loan Bank Due July 22, 2016 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt		14,977
Significant Other Observable Inputs (Level 2) [Member] | One Point Twenty Five Percent Borrowing From Federal Home Loan Bank [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt	45,072	45,083
Significant Other Observable Inputs (Level 2) [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	107,829	181,880
Significant Other Observable Inputs (Level 2) [Member] | Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	18,160	18,679
Significant Other Observable Inputs (Level 2) [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	51	1,028
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	2,363	4,621
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	7,691	3,336
Short-term debt	0	0
Long-term debt	0	0
Significant Unobservable Inputs (Level 3) [Member] | Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0	0
Significant Unobservable Inputs (Level 3) [Member] | Six Point Seventy Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0	0
Significant Unobservable Inputs (Level 3) [Member] | Five Point Eight Hundred Seventy Five Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0
Significant Unobservable Inputs (Level 3) [Member] | Zero Point Sixty Three Percent Borrowing From Federal Home Loan Bank Due July 22, 2016 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt		0
Significant Unobservable Inputs (Level 3) [Member] | One Point Twenty Five Percent Borrowing From Federal Home Loan Bank [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term debt	0	0
Significant Unobservable Inputs (Level 3) [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	7,691	3,336
Significant Unobservable Inputs (Level 3) [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	$ 0	$ 0

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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Premiums written:
Direct	$ 669,844	$ 631,429	$ 1,981,984	$ 1,851,620
Assumed	7,644	6,099	21,752	17,140
Ceded	(98,715)	(92,503)	(281,464)	(273,514)
Net	578,773	545,025	1,722,272	1,595,246
Premiums earned:
Direct	627,520	590,716	1,846,587	1,728,865
Assumed	7,163	5,830	20,604	16,831
Ceded	(92,254)	(89,156)	(270,372)	(271,874)
Net	542,429	507,390	1,596,819	1,473,822
Loss and loss expense incurred:
Direct	428,520	306,635	1,152,223	935,529
Assumed	5,929	4,224	18,424	13,114
Ceded	(118,191)	(25,698)	(258,766)	(86,922)
Net	316,258	285,161	911,881	861,721
National Flood Insurance Program [Member]
Premiums written:
Ceded	(62,051)	(62,463)	(179,205)	(178,784)
Premiums earned:
Ceded	(56,505)	(58,340)	(169,986)	(176,119)
Loss and loss expense incurred:
Ceded	$ (99,200)	$ (15,382)	$ (164,179)	$ (36,315)

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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Ceded premiums written	$ (98,715)	$ (92,503)	$ (281,464)	$ (273,514)
Ceded premiums earned	(92,254)	(89,156)	(270,372)	(271,874)
Ceded loss and loss expense incurred	(118,191)	(25,698)	(258,766)	(86,922)
National Flood Insurance Program [Member]
Ceded premiums written	(62,051)	(62,463)	(179,205)	(178,784)
Ceded premiums earned	(56,505)	(58,340)	(169,986)	(176,119)
Ceded loss and loss expense incurred	$ (99,200)	$ (15,382)	$ (164,179)	$ (36,315)
Percentage of NFIP claims ceded by federal government			100.00%

Segment Information Narrative (

Segment Information Narrative (Details)	9 Months Ended
	Sep. 30, 2016
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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Total net premiums earned	$ 542,429	$ 507,390	$ 1,596,819	$ 1,473,822
Net investment income	33,375	32,061	95,326	91,208
Net realized investment gains	3,688	308	2,749	15,771
Total investment revenues	37,063	32,369	98,075	106,979
Other income	2,199	698	7,018	5,521
Total revenues	581,691	540,457	1,701,912	1,586,322
Standard Commercial Lines [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	423,511	389,990	1,241,934	1,136,960
Standard Commercial Lines [Member] | Commercial Automobile [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	100,612	90,758	294,927	265,771
Standard Commercial Lines [Member] | Workers Compensation [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	78,596	74,560	229,847	213,991
Standard Commercial Lines [Member] | General Liability [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	133,981	123,252	391,349	357,430
Standard Commercial Lines [Member] | Commercial Property [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	74,052	68,587	217,821	199,699
Standard Commercial Lines [Member] | Business Owners' Policies [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	24,461	23,726	73,016	69,603
Standard Commercial Lines [Member] | Bonds Segment [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	5,795	5,031	16,924	15,137
Standard Commercial Lines [Member] | Other Commercial [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	4,089	3,628	11,868	10,649
Standard Commercial Lines [Member] | Miscellaneous Income [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	1,925	448	6,182	4,680
Standard Personal Lines [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	68,965	72,338	210,555	217,479
Standard Personal Lines [Member] | Miscellaneous Income [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	275	250	836	841
Standard Personal Lines [Member] | Personal Automobile [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	34,865	36,623	106,526	110,373
Standard Personal Lines [Member] | Homeowners [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	32,031	33,670	98,342	101,122
Standard Personal Lines [Member] | Other Personal [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	1,794	1,795	4,851	5,143
Excess And Surplus Operations [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	52,152	45,760	151,348	124,904
Excess And Surplus Operations [Member] | Commercial Automobile [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	2,902	2,056	7,963	5,562
Excess And Surplus Operations [Member] | General Liability [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	37,398	32,395	108,372	87,914
Excess And Surplus Operations [Member] | Commercial Property [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	11,853	11,309	35,013	31,428
Excess And Surplus Operations [Member] | Miscellaneous Income [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	$ (1)	$ 0	$ 0	$ 0

Segment Information (Income Bef

Segment Information (Income Before Federal Income Tax) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Net investment income	$ 33,375	$ 32,061	$ 95,326	$ 91,208
Net realized investment gains	3,688	308	2,749	15,771
Total investment income, before federal income tax	37,063	32,369	98,075	106,979
Tax on investment income	9,752	7,614	24,290	26,186
Total investment income, after federal income tax	27,311	24,755	73,785	80,793
Standard Commercial Lines [Member]
Segment Reporting Information [Line Items]
Underwriting gain (loss), before federal income tax	$ 30,124	$ 44,027	$ 101,229	$ 109,304
GAAP combined ratio	92.90%	88.70%	91.80%	90.30%
Statutory combined ratio	92.00%	88.40%	90.10%	89.40%
Standard Personal Lines [Member]
Segment Reporting Information [Line Items]
Underwriting gain (loss), before federal income tax	$ 4,271	$ 2,826	$ 19,001	$ (4,295)
GAAP combined ratio	93.80%	96.10%	90.90%	102.00%
Statutory combined ratio	92.00%	95.00%	90.70%	101.70%
Excess And Surplus Operations [Member]
Segment Reporting Information [Line Items]
Underwriting gain (loss), before federal income tax	$ (2,362)	$ (2,022)	$ (3,465)	$ (5,033)
GAAP combined ratio	104.50%	104.40%	102.30%	104.00%
Statutory combined ratio	101.40%	101.10%	100.90%	101.80%

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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Investment income, before federal income tax	$ 37,063	$ 32,369	$ 98,075	$ 106,979
Interest expense	(5,714)	(5,610)	(16,940)	(16,826)
General corporate and other expenses	(7,939)	(5,751)	(28,271)	(21,235)
Income before federal income tax	55,443	65,839	169,629	168,894
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	30,124	44,027	101,229	109,304
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	4,271	2,826	19,001	(4,295)
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	(2,362)	(2,022)	(3,465)	(5,033)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total all segments	$ 69,096	$ 77,200	$ 214,840	$ 206,955

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		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 41	$ 1,913	$ 1,647	$ 5,738
Interest cost	3,049	3,409	9,252	10,225
Expected return on plan assets	(5,006)	(3,991)	(12,982)	(11,972)
Amortization of unrecognized net actuarial loss	1,763	1,643	4,724	4,930
Total net periodic cost	$ (153)	$ 2,974	2,641	$ 8,921
Estimated contribution from employer					$ 11,700
Defined Benefit Plan, Contributions by Employer			$ 54,500

Retirement Plans (Weighted-Aver

Retirement Plans (Weighted-Average Expense Assumptions) (Details) - Pension Plan [Member]	3 Months Ended	9 Months Ended
	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate		4.69%	4.29%
Effective interest rate for calculation of service cost		4.89%	0.00%
Effective interest rate for calculation of interest cost		4.02%	0.00%
Expected return on plan assets		6.37%	6.27%
Rate of compensation increase	4.00%		4.00%

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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income, Gross	$ 55,443	$ 65,839	$ 169,629	$ 168,894
Unrealized holding (losses) gains during the period, Gross	(12,992)	8,371	108,420	(27,896)
Non-credit portion of OTTI recognized in OCI, Gross			(10)
Amounts reclassified into net income: HTM securities, Gross	(13)	(97)	(104)	(543)
Amounts reclassified into net income: Non-credit OTTI, Gross				357
Realized gains on AFS securities, Gross	(3,684)	(305)	(2,747)	(16,778)
Total unrealized (losses) gains on investment securities, Gross	(16,689)	7,969	105,559	(44,860)
Amount reclassified into net income: Net actuarial loss, Gross	1,615	1,709	4,648	5,127
Total defined pension and other post-retirement benefit plans, Gross	1,615	1,709	4,648	5,127
Other comprehensive (loss) income, Gross	(15,074)	9,678	110,207	(39,733)
Comprehensive income before tax	40,369	75,517	279,836	129,161
Net income, Tax	16,941	18,843	50,494	48,422
Unrealized holding (losses) gains during the period, Tax	(4,548)	2,929	37,947	(9,764)
Non-credit portion of OTTI recognized in OCI, Tax			(4)
Amounts reclassified into net income: HTM securities, Tax	(4)	(34)	(36)	(190)
Amounts reclassified into net income: Non-credit OTTI, Tax				125
Realized gains on AFS securities, Tax	(1,289)	(106)	(961)	(5,872)
Total unrealized (losses) gains on investment securities, Tax	(5,841)	2,789	36,946	(15,701)
Amount reclassified into net income: Net actuarial loss, Tax	565	599	1,627	1,795
Total defined pension and other post-retirement benefit plans, Tax	565	599	1,627	1,795
Other comprehensive (loss) income, Tax	(5,276)	3,388	38,573	(13,906)
Comprehensive income, Tax	11,665	22,231	89,067	34,516
Net income	38,502	46,996	119,135	120,472
Unrealized holding (losses) gains arising during period	(8,444)	5,442	70,473	(18,132)
Non-credit portion of OTTI recognized in OCI			(6)
Amounts reclassified into net income: HTM Securities	(9)	(63)	(68)	(353)
Amounts reclassified into net income: Non-credit OTTI	0	0	0	232
Realized gains on available-for-sale securities	(2,395)	(199)	(1,786)	(10,906)
Total unrealized (losses) gains on investment securities	(10,848)	5,180	68,613	(29,159)
Amount reclassified into net income: Net actuarial loss	1,050	1,110	3,021	3,332
Total defined benefit pension and post-retirement plans	1,050	1,110	3,021	3,332
Other comprehensive (loss) income	(9,798)	6,290	71,634	(25,827)
Comprehensive income	$ 28,704	$ 53,286	$ 190,769	$ 94,645

Comprehensive Income (Compone56

Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2015			$ (9,425)
Amounts reclassified into net income: Non-credit OTTI	$ 0	$ 0	0	$ 232
OCI before reclassifications, Defined Benefit Pension and Post Retirement Plans			0
Amount reclassified into net income: Net actuarial loss	1,050	1,110	3,021	3,332
Amounts reclassified from AOCI, HTM related	(9)	(63)	(68)	(353)
Amounts reclassified from AOCI, All Other	(2,395)	(199)	(1,786)	(10,906)
Other comprehensive income	(9,798)	6,290	71,634	(25,827)
Other Comprehensive Income, Defined Benefit Pension and Post Retirement Plans, Adjustment, Net of Tax	1,050	$ 1,110	3,021	3,332
Ending Balance, September 30, 2016	62,209		62,209
Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2015			45,083
OCI before reclassifications			70,473
Other comprehensive income			68,687
Ending Balance, September 30, 2016	113,770		113,770
Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2015			44,995
OCI before reclassifications			70,467
Amounts reclassified from AOCI			(1,854)
Other comprehensive income			68,613
Ending Balance, September 30, 2016	113,608		113,608
Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2015			(282)
OCI before reclassifications			(6)
Other comprehensive income			(6)
Ending Balance, September 30, 2016	(288)		(288)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Held-to-maturity Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2015			194
OCI before reclassifications			0
Other comprehensive income			(68)
Ending Balance, September 30, 2016	126		126
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2015			(54,420)
Amount reclassified into net income: Net actuarial loss			3,021
Ending Balance, September 30, 2016	(51,399)		(51,399)
Accumulated other comprehensive income (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2015			(9,425)
OCI before reclassifications			70,467
Amounts reclassified from AOCI			1,167
Other comprehensive income			71,634	$ (25,827)
Ending Balance, September 30, 2016	$ 62,209		$ 62,209

Comprehensive Income (Reclassif

Comprehensive Income (Reclassification out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Total net realized gains	$ 3,688	$ 308	$ 2,749	$ 15,771
Net investment income	33,375	32,061	95,326	91,208
Loss and loss expense incurred	316,258	285,161	911,881	861,721
Policy acquisition costs	193,835	174,802	567,793	509,295
Income before federal income tax	55,443	65,839	169,629	168,894
Total federal income tax expense	(16,941)	(18,843)	(50,494)	(48,422)
Net income	38,502	46,996	119,135	120,472
Reclassification out of AOCI
Net income	(1,354)	848	1,167	(7,695)
Pension Plan [Member] | Reclassification out of AOCI
Loss and loss expense incurred	351	371	1,009	1,114
Policy acquisition costs	1,264	1,338	3,639	4,013
Income before federal income tax	1,615	1,709	4,648	5,127
Total federal income tax expense	(565)	(599)	(1,627)	(1,795)
Net income	1,050	1,110	3,021	3,332
Non-credit OTTI on Disposed Securities [Member] | Reclassification out of AOCI
Total net realized gains	0	0	0	357
Income before federal income tax	0	0	0	357
Total federal income tax expense	0	0	0	(125)
Net income	0	0	0	232
Held-to-maturity Securities [Member] | Reclassification out of AOCI
Total net realized gains	73	121	161	258
Net investment income	(86)	(218)	(265)	(801)
Income before federal income tax	(13)	(97)	(104)	(543)
Total federal income tax expense	4	34	36	190
Net income	(9)	(63)	(68)	(353)
Available-for-sale Securities [Member] | Reclassification out of AOCI
Total net realized gains	(3,684)	(305)	(2,747)	(16,778)
Income before federal income tax	(3,684)	(305)	(2,747)	(16,778)
Total federal income tax expense	1,289	106	961	5,872
Net income	$ (2,395)	$ (199)	$ (1,786)	$ (10,906)

Subsequent Events Subsequent 58

Subsequent Events Subsequent Events (Details) - Subsequent Event [Member] $ in Millions	3 Months Ended
	Dec. 31, 2016USD ($)
Subsequent Event [Line Items]
Flood Claims Handling Fees	$ 1
Minimum [Member]
Subsequent Event [Line Items]
Estimated Catastrophe Losses	10
Maximum [Member]
Subsequent Event [Line Items]
Estimated Catastrophe Losses	$ 14