Selective Insurance (SIGI) 10-Q 27 Apr 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 14, 2017
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Entity Registrant Name	SELECTIVE INSURANCE GROUP INC
Entity Central Index Key	230,557
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock , Shares Outstanding		58,248,140

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
ASSETS
Fixed income securities, held-to-maturity – at carrying value (fair value: $88,339 – 2017; $105,211 – 2016)	$ 84,836	$ 101,556
Fixed income securities, available-for-sale – at fair value (amortized cost: $4,805,368 – 2017; $4,753,759 – 2016)	4,867,005	4,792,540
Equity securities, available-for-sale – at fair value (cost: $124,614 – 2017; $120,889 – 2016)	154,918	146,753
Short-term investments (at cost which approximates fair value)	247,207	221,701
Other investments	106,796	102,397
Total investments (Note 4 and 6)	5,460,762	5,364,947
Cash	483	458
Interest and dividends due or accrued	40,239	40,164
Premiums receivable, net of allowance for uncollectible accounts of: $6,613 – 2017; $5,980 – 2016	707,677	681,611
Reinsurance recoverable, net of allowance for uncollectible accounts of: $5,000 – 2017; $5,500 – 2016	580,386	621,537
Prepaid reinsurance premiums	145,436	146,282
Current federal income tax	0	2,486
Deferred federal income tax	72,218	84,840
Property and equipment – at cost, net of accumulated depreciation and amortization of: $202,917 – 2017; $198,729 – 2016	68,503	69,576
Deferred policy acquisition costs	227,622	222,564
Goodwill	7,849	7,849
Other assets	92,921	113,534
Total assets	7,404,096	7,355,848
Liabilities And Stockholders' Equity
Reserve for losses and loss expenses (Note 8)	3,679,471	3,691,719
Unearned premiums	1,299,823	1,262,819
Long-term debt	438,782	438,667
Current federal income tax	11,552	0
Accrued salaries and benefits	96,322	132,880
Other liabilities	285,567	298,393
Total liabilities	5,811,517	5,824,478
Stockholders' Equity:
Preferred stock of $0 par value per share: Authorized shares: 5,000,000; no shares issued or outstanding	0	0
Common stock of $2 par value per share: Authorized shares: 360,000,000; Issued: 102,028,447 – 2017; 101,620,436 – 2016	204,057	203,241
Additional paid-in capital	354,239	347,295
Retained earnings	1,609,862	1,568,881
Accumulated other comprehensive income (loss) (Note 11)	2,090	(15,950)
Treasury stock – at cost (shares: 43,780,884 – 2017; 43,653,237 – 2016)	(577,669)	(572,097)
Total stockholders' equity	1,592,579	1,531,370
Commitments and contingencies
Total liabilities and stockholders' equity	$ 7,404,096	$ 7,355,848

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fixed income securities, held-to-maturity, fair value	$ 88,339	$ 105,211
Fixed income securities, available-for-sale, amortized cost	4,850,368	4,753,759
Equity securities, available-for-sale, cost	124,614	120,889
Premiums receivable, allowance for uncollectible accounts	6,613	5,980
Reinsurance recoverable, allowance for uncollectible accounts	5,000	5,500
Property and equipment - at cost, accumulated depreciation and amortization	$ 202,917	$ 198,729
Preferred stock, par value per share	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 2	$ 2
Common stock, shares authorized	360,000,000	360,000,000
Common stock, shares issued	102,028,447	101,620,436
Treasury stock - at cost, shares	43,780,884	43,653,237

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues:
Net premiums earned	$ 560,854	$ 522,458
Net investment income earned	37,419	30,769
Net realized losses:
Net realized investment gains	2,430	889
Other-than-temporary impairments	(3,475)	(3,593)
Total net realized losses	(1,045)	(2,704)
Other income	3,241	951
Total revenues	600,469	551,474
Expenses:
Losses and loss expenses incurred	317,472	297,144
Policy acquisition costs	196,228	183,227
Interest expense	6,106	5,606
Other expenses	13,089	13,622
Total expenses	532,895	499,599
Income before federal income tax	67,574	51,875
Federal income tax expense:
Current	14,273	14,084
Deferred	2,861	759
Total federal income tax expense	17,134	14,843
Net income	$ 50,440	$ 37,032
Earnings per share:
Basic net income	$ 0.87	$ 0.64
Diluted net income	0.85	0.63
Dividends to stockholders	$ 0.16	$ 0.15

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 50,440	$ 37,032
Unrealized holding gains arising during period	16,761	42,729
Amounts reclassified into net income: Held-to-maturity securities	(32)	(47)
Amounts reclassified into net income: Realized losses on available-for-sale securities	981	1,754
Total unrealized gains on investment securities	17,710	44,436
Amount reclassified into net income: Net actuarial loss	330	986
Total defined benefit pension and post-retirement plans	330	986
Other comprehensive income	18,040	45,422
Comprehensive income	$ 68,480	$ 82,454

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, 2015		$ 201,723	$ 326,656	$ 1,446,192	$ (9,425)	$ (567,105)
Dividend reinvestment plan (shares: 8,249 – 2017; 10,931 – 2016)		22	351
Stock purchase and compensation plans (shares: 399,762 – 2017; 386,567 – 2016)		773	6,958
Net income	$ 37,032			37,032
Dividends to stockholders ($0.16 per share – 2017; $0.15 per share – 2016)				(8,789)
Other comprehensive income	45,422				45,422
Acquisition of treasury stock (shares: 127,647 – 2017; 122,250 – 2016)						(3,845)
End of period at Mar. 31, 2016	1,475,965	202,518	333,965	1,474,435	35,997	(570,950)
Beginning of year at Dec. 31, 2016	1,531,370	203,241	347,295	1,568,881	(15,950)	(572,097)
Dividend reinvestment plan (shares: 8,249 – 2017; 10,931 – 2016)		16	348
Stock purchase and compensation plans (shares: 399,762 – 2017; 386,567 – 2016)		800	6,596
Net income	50,440			50,440
Dividends to stockholders ($0.16 per share – 2017; $0.15 per share – 2016)				(9,459)
Other comprehensive income	18,040				18,040
Acquisition of treasury stock (shares: 127,647 – 2017; 122,250 – 2016)						(5,572)
End of period at Mar. 31, 2017	$ 1,592,579	$ 204,057	$ 354,239	$ 1,609,862	$ 2,090	$ (577,669)

Consolidated Statements of Sto7

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Dividend reinvestment plan, shares	8,249	10,931
Stock purchase and compensation plans, shares	399,762	386,567
Dividends to stockholders, per share	$ 0.16	$ 0.15
Acquisition of treasury stock, shares	127,647	122,250
Preferred stock, par value per share	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Series A Preferred Stock [Member]
Preferred stock, par value per share	$ 0	$ 0
Preferred stock, shares authorized	300,000	300,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flow - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Activities
Net income	$ 50,440	$ 37,032
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,882	14,627
Stock-based compensation expense	5,273	4,377
Undistributed (gains) losses of equity method investments	(665)	1,066
Loss on disposal of fixed assets	998	0
Net realized losses	1,045	2,704
Changes in assets and liabilities:
Increase in reserve for losses and loss expenses, net of reinsurance recoverable	28,903	42,390
Increase in unearned premiums, net of prepaid reinsurance	37,850	42,901
Decrease in net federal income taxes	16,946	5,296
Increase in premiums receivable	(26,066)	(39,180)
Increase in deferred policy acquisition costs	(5,058)	(7,789)
(Increase) decrease in interest and dividends due or accrued	(218)	528
Decrease in accrued salaries and benefits	(36,558)	(27,115)
Decrease (increase) in other assets	15,998	(10,128)
Decrease in other liabilities	(55,175)	(52,902)
Net cash provided by operating activities	46,595	13,807
Investing Activities
Purchase of fixed income securities, available-for-sale	(724,880)	(264,828)
Purchase of equity securities, available-for-sale	(14,083)	(7,574)
Purchase of other investments	(11,211)	(12,723)
Purchase of short-term investments	(1,027,885)	(303,228)
Sale of fixed income securities, available-for-sale	594,805	12,905
Sale of short-term investments	1,010,917	394,915
Redemption and maturities of fixed income securities, held-to-maturity	16,527	37,400
Redemption and maturities of fixed income securities, available-for-sale	116,357	130,641
Sale of equity securities, available-for-sale	5,503	4,285
Distributions from other investments	6,428	7,994
Purchase of property and equipment	(4,937)	(3,439)
Net cash used in investing activities	(32,459)	(3,652)
Financing Activities
Dividends to stockholders	(8,955)	(8,270)
Acquisition of treasury stock	(5,572)	(3,845)
Net proceeds from stock purchase and compensation plans	1,563	1,478
Proceeds from borrowings	64,000	25,000
Repayments of borrowings	(64,000)	(25,000)
Excess tax benefits from share-based payment arrangements	0	1,361
Repayments of capital lease obligations	(1,147)	(1,094)
Net cash used in financing activities	(14,111)	(10,370)
Net increase (decrease) in cash	25	(215)
Cash, beginning of year	458	898
Cash, end of period	$ 483	$ 683

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2017
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. 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 first quarters ended March 31, 2017 (“ First Quarter 2017 ”) and March 31, 2016 (“ First Quarter 2016 ”). 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, 2016 (“ 2016 Annual Report ”) filed with the SEC.

Accounting Pronouncements

Accounting Pronouncements	3 Months Ended
	Mar. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Accounting Pronouncements	Accounting Pronouncements In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standard Update ("ASU") 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-based Payment Accounting (“ASU 2016-09”). ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions. We adopted this guidance on January 1, 2017, which resulted in the following impacts on our consolidated financial statements: Consolidated Statements of Income The new standard requires that the tax effects of share-based compensation be recognized in the income tax provision as discrete items outside of the annual estimated expected tax rate. In addition, all excess tax benefits and tax deficiencies should be recognized as income tax benefit or expense in the income statement. Previously, these amounts were recorded in additional paid-in capital. In addition, in calculating potential common shares used to determine diluted earnings per share, GAAP requires us to use the treasury stock method. The new standard requires that assumed proceeds under the treasury stock method be modified to exclude the amount of excess tax benefits that would have been recognized in additional paid-in capital. These changes were adopted on a prospective basis. As a result of adoption, we recognized an income tax benefit in the Consolidated Statements of Income of $2.9 million in First Quarter 2017 related to grants that have vested this quarter. In recording share-based compensation expense, the standard allows companies to make a policy election as to whether they will include an estimate of awards expected to be forfeited or whether they will account for forfeitures as they occur. We have elected to include an estimate of forfeitures in the computation of our share-based compensation expense. As this treatment is consistent with previous guidance, this election had no impact on our consolidated financial statements. Consolidated Statements of Cash Flows ASU 2016-09 requires that excess tax benefits from share-based awards be reported as operating activities in the consolidated statement of cash flows. Previously, these cash flows were included in financing activities. We elected to apply this change on a prospective basis; therefore, no changes have been made to the prior periods disclosed in this report. The standard also requires that employee taxes paid when an employer withholds shares for tax-withholding purposes be reported as financing activities in the consolidated statement of cash flows. This requirement has no impact to us as we have historically reported these cash flows as part of financing activities. In October 2016, the FASB issued ASU 2016-17, Consolidation: Interests Held through Related Parties That Are Under Common Control ("ASU 2016-17"). ASU 2016-17 changes how a decision maker considers indirect interests in a variable interest entity ("VIE") held under common control in making the primary beneficiary determination. ASU 2016-17 was effective for annual periods beginning after December 15, 2016, including interim periods within those annual periods. The adoption of ASU 2016-17 did not impact us, as we are not the decision maker in any of the VIEs in which we are invested. Pronouncements to be effective in the future In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). ASU 2016-01 provides guidance to improve certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. Specifically the guidance: (i) requires equity 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 is permitted only as of January 1, 2017, 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 (“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 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. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows: Restricted Cash ("ASU 2016-18"). ASU 2016-18, requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents in the reconciliation of beginning and ending cash on the statements of cash flows. This update also requires a reconciliation of the statement of the cash flows to the balance sheet if the balance sheet includes more than one line item of cash, cash equivalents, and restricted cash. ASU 2016-18 is effective, with retrospective adoption, for annual periods beginning after December 15, 2017, and interim periods within those annual periods. We currently have restricted cash associated with the National Flood Insurance Program ("NFIP") in "Other assets." This literature will impact the presentation of this item in both the Consolidated Balance Sheets and the Statements of Cash Flows. In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). ASU 2017-04 eliminates the second step of the two part goodwill impairment test, which required entities to determine the fair value of individual assets and liabilities of a reporting unit to measure the goodwill impairment. Under the new guidance, a goodwill impairment is calculated as the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The amendments in this update should be applied on a prospective basis for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We do not expect a material impact on our financial condition or results of operations from the adoption of this guidance. In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost ("ASU 2017-07"). ASU 2017-07 requires that an employer report a pension plan's service cost in the same line item or line items as other compensation costs arising from services rendered by pertinent employees during the period. ASU 2017-07 also requires that other components of net benefit cost be presented in the income statement separately from the service cost component. If a separate line item or items are not used, the line item or items used in the income statement to present the other components of net benefit cost must be disclosed. ASU 2017-07 is effective for annual periods beginning after December 15, 2017 including interim periods within those annual periods with early adoption permitted at the beginning of an annual period. As our pension plan was frozen as of March 2016, we have ceased accruing additional service fee costs since that time. Therefore, the application of this guidance is not anticipated to impact our financial condition, results of operations, or disclosures. In March 2017, the FASB issued ASU 2017-08, Receivables-Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities ("ASU 2017-08"). ASU 2017-08 revises the amortization period for certain callable debt securities held at a premium, requiring the premium to be amortized to the earliest call date. Under current GAAP, entities generally amortize the premium as an adjustment of yield over the contractual life of the instrument. ASU 2017-08 is effective for annual periods and interim periods within those annual periods beginning after December 15, 2018 with early adoption permitted. This ASU does not impact us as we amortize premium on these callable debt securities to the earliest call date.

Statements of Cash Flow

Statements of Cash Flow	3 Months Ended
	Mar. 31, 2017
Supplemental Cash Flow Information [Abstract]
Statements of Cash Flow	Statements of Cash Flows Supplemental cash flow information was as follows: Quarter ended March 31, ($ in thousands) 2017 2016 Cash paid during the period for: Interest $ 3,409 2,904 Federal income tax — 8,000 Non-cash items: Exchange of fixed income securities, AFS 1,029 9,872 Assets acquired under capital lease arrangements 278 2,598 Non-cash purchase of property and equipment — 152 1 Examples of such corporate actions include non-cash acquisitions and stock splits. Included in "Other assets" on the Consolidated Balance Sheets was $14.4 million at March 31, 2017 and $13.5 million at March 31, 2016 of cash received from the NFIP, which is restricted to pay flood claims under the Write Your Own ("WYO") program.

Investments

Investments	3 Months Ended
	Mar. 31, 2017
Investments [Abstract]
Investments	Investments (a) Information regarding our held-to-maturity ("HTM") fixed income securities as of March 31, 2017 and December 31, 2016 was as follows: March 31, 2017 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states and political subdivisions $ 62,534 245 62,779 1,981 — 64,760 Corporate securities 22,194 (137 ) 22,057 1,614 (92 ) 23,579 Total HTM fixed income securities $ 84,728 108 84,836 3,595 (92 ) 88,339 December 31, 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 $ 77,466 317 77,783 2,133 — 79,916 Corporate securities 22,711 (143 ) 22,568 1,665 (158 ) 24,075 Commercial mortgage-backed securities ("CMBS") 1,220 (15 ) 1,205 15 — 1,220 Total HTM fixed income securities $ 101,397 159 101,556 3,813 (158 ) 105,211 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. (b) Information regarding our AFS securities as of March 31, 2017 and December 31, 2016 was as follows: March 31, 2017 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 86,816 1,566 (44 ) 88,338 Foreign government 31,965 628 — 32,593 Obligations of states and political subdivisions 1,261,191 28,923 (2,948 ) 1,287,166 Corporate securities 1,799,706 30,493 (2,073 ) 1,828,126 Collateralized loan obligations and other asset-backed securities ("CLO and other ABS") 675,838 2,998 (401 ) 678,435 CMBS 263,217 1,314 (775 ) 263,756 Residential mortgage-backed securities (“RMBS”) 686,635 3,623 (1,667 ) 688,591 Total AFS fixed income securities 4,805,368 69,545 (7,908 ) 4,867,005 AFS equity securities: Common stock 108,466 30,150 (285 ) 138,331 Preferred stock 16,148 480 (41 ) 16,587 Total AFS equity securities 124,614 30,630 (326 ) 154,918 Total AFS securities $ 4,929,982 100,175 (8,234 ) 5,021,923 December 31, 2016 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 75,139 2,230 (36 ) 77,333 Foreign government 26,559 322 (16 ) 26,865 Obligations of states and political subdivisions 1,366,287 18,610 (5,304 ) 1,379,593 Corporate securities 1,976,556 27,057 (5,860 ) 1,997,753 CLO and other ABS 527,876 1,439 (355 ) 528,960 CMBS 256,356 1,514 (1,028 ) 256,842 RMBS 524,986 3,006 (2,798 ) 525,194 Total AFS fixed income securities 4,753,759 54,178 (15,397 ) 4,792,540 AFS equity securities: Common stock 104,663 26,250 (305 ) 130,608 Preferred stock 16,226 274 (355 ) 16,145 Total AFS equity securities 120,889 26,524 (660 ) 146,753 Total AFS securities $ 4,874,648 80,702 (16,057 ) 4,939,293 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 table below provides our net unrealized/unrecognized loss positions by impairment severity for both AFS and HTM securities as of March 31, 2017 compared to December 31, 2016 . ($ in thousands) March 31, 2017 December 31, 2016 Number of Issues % of Market/Book Unrealized/ Unrecognized Loss Number of Issues % of Market/Book Unrealized/ Unrecognized Loss 304 80% - 99% $ 8,326 456 80% - 99% $ 16,215 — 60% - 79% — — 60% - 79% — — 40% - 59% — — 40% - 59% — — 20% - 39% — — 20% - 39% — — 0% - 19% — — 0% - 19% — $ 8,326 $ 16,215 The severity of impairment on the securities in the table above averaged 1% of amortized cost at March 31, 2017 and December 31, 2016 . Quantitative information regarding unrealized losses on our AFS portfolio is provided below. Our HTM portfolio had $0.1 million in unrealized/unrecognized losses at March 31, 2017 and $0.2 million in unrealized/unrecognized losses at December 31, 2016 . March 31, 2017 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 Fair Value Unrealized 1 AFS fixed income securities: U.S. government and government agencies $ 9,012 (44 ) — — 9,012 (44 ) Obligations of states and political subdivisions 114,632 (2,948 ) — — 114,632 (2,948 ) Corporate securities 229,836 (2,068 ) 244 (5 ) 230,080 (2,073 ) CLO and other ABS 137,388 (400 ) 310 (1 ) 137,698 (401 ) CMBS 80,494 (775 ) — — 80,494 (775 ) RMBS 212,486 (1,588 ) 2,246 (79 ) 214,732 (1,667 ) Total AFS fixed income securities 783,848 (7,823 ) 2,800 (85 ) 786,648 (7,908 ) AFS equity securities: Common stock 10,088 (285 ) — — 10,088 (285 ) Preferred stock 1,527 (41 ) — — 1,527 (41 ) Total AFS equity securities 11,615 (326 ) — — 11,615 (326 ) Total AFS $ 795,463 (8,149 ) 2,800 (85 ) 798,263 (8,234 ) December 31, 2016 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 Fair Value Unrealized 1 AFS fixed income securities: U.S. government and government agencies $ 6,419 (36 ) — — 6,419 (36 ) Foreign government 13,075 (16 ) — — 13,075 (16 ) Obligations of states and political subdivisions 306,509 (5,304 ) — — 306,509 (5,304 ) Corporate securities 462,902 (5,771 ) 4,913 (89 ) 467,815 (5,860 ) CLO and other ABS 189,795 (354 ) 319 (1 ) 190,114 (355 ) CMBS 82,492 (1,021 ) 1,645 (7 ) 84,137 (1,028 ) RMBS 279,480 (2,489 ) 8,749 (309 ) 288,229 (2,798 ) Total AFS fixed income securities 1,340,672 (14,991 ) 15,626 (406 ) 1,356,298 (15,397 ) AFS equity securities: Common stock 11,271 (305 ) — — 11,271 (305 ) Preferred stock 6,168 (355 ) — — 6,168 (355 ) Total AFS equity securities 17,439 (660 ) — — 17,439 (660 ) Total AFS $ 1,358,111 (15,651 ) 15,626 (406 ) 1,373,737 (16,057 ) 1 Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI. 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 2016 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 March 31, 2017 , 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 March 31, 2017 : ($ in thousands) Carrying Value Fair Value Due in one year or less $ 39,376 39,876 Due after one year through five years 37,028 39,365 Due after five years through 10 years 8,432 9,098 Total HTM fixed income securities $ 84,836 88,339 Listed below are the contractual maturities of AFS fixed income securities at March 31, 2017 : ($ in thousands) Fair Value Due in one year or less $ 331,997 Due after one year through five years 1,989,887 Due after five years through 10 years 2,294,091 Due after 10 years 251,030 Total AFS fixed income securities $ 4,867,005 (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 March 31, 2017 December 31, 2016 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Alternative Investments Private equity $ 41,354 74,669 116,023 41,135 76,774 117,909 Private credit 31,026 40,745 71,771 28,193 40,613 68,806 Real assets 16,265 27,764 44,029 14,486 22,899 37,385 Total alternative investments 88,645 143,178 231,823 83,814 140,286 224,100 Other securities 18,151 267 18,418 18,583 3,400 21,983 Total other investments $ 106,796 143,445 250,241 102,397 143,686 246,083 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 2017 or 2016 . For a description of our alternative investment strategies, as well as information regarding redemption, restrictions, and fund liquidations, refer to Note 5. “Investments” in Item 8. “Financial Statements and Supplementary Data.” of our 2016 Annual Report . 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 month periods ended December 31 is as follows: Income Statement Information Quarter ended December 31, ($ in millions) 2016 2015 Net investment (loss) income $ 25.6 46.6 Realized gains (235.1 ) 752.5 Net change in unrealized depreciation 561.5 (883.2 ) Net gain $ 352.0 (84.1 ) Selective’s insurance subsidiaries’ other investments gain (loss) $ 1.6 (1.1 ) (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 March 31, 2017 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 March 31, 2017 : ($ in millions) FHLBI Collateral FHLBNY Collateral State and Regulatory Deposits Total U.S. government and government agencies $ 4.3 — 24.4 28.7 CMBS 3.6 4.8 — 8.4 RMBS 60.4 53.9 — 114.3 Total pledged as collateral $ 68.3 58.7 24.4 151.4 (g) We did not have exposure to any credit concentration risk of a single issuer greater than 10% of our stockholders' equity, other than certain U.S. government-backed investments, as of March 31, 2017 or December 31, 2016 . (h) The components of pre-tax net investment income earned were as follows: Quarter ended March 31, ($ in thousands) 2017 2016 Fixed income securities $ 36,891 31,644 Equity securities 1,468 2,230 Short-term investments 250 159 Other investments 1,603 (1,066 ) Investment expenses (2,793 ) (2,198 ) Net investment income earned $ 37,419 30,769 (i) The following tables summarize OTTI by asset type for the periods indicated: First Quarter 2017 Gross Included in Other Comprehensive Income ("OCI") Recognized in ($ in thousands) AFS fixed income securities: U.S. government and government agencies 29 — 29 Obligations of states and political subdivisions 373 — 373 Corporate securities 194 — 194 CLO and other ABS 23 — 23 CMBS 450 — 450 RMBS 1,092 — 1,092 Total AFS fixed income securities 2,161 — 2,161 AFS equity securities: Common stock $ 1,314 — 1,314 Total AFS equity securities 1,314 — 1,314 Total OTTI losses $ 3,475 — 3,475 First Quarter 2016 Gross Included in OCI Recognized in ($ in thousands) AFS fixed income securities: Corporate securities $ 973 — 973 Total AFS fixed income securities 973 — 973 AFS equity securities: Common stock 2,617 — 2,617 Preferred stock 3 — 3 Total AFS equity securities 2,620 — 2,620 Total OTTI losses $ 3,593 — 3,593 For a discussion of our evaluation for OTTI refer to Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2016 Annual Report . (j) The components of net realized gains, excluding OTTI charges, for the periods indicated were as follows: Quarter ended March 31, ($ in thousands) 2017 2016 HTM fixed income securities Gains $ — — Losses (1 ) (1 ) AFS fixed income securities Gains 3,552 620 Losses (1,587 ) (36 ) AFS equity securities Gains — 330 Losses — (20 ) Other investments Gains 480 — Losses (14 ) (4 ) Total net realized gains (excluding OTTI charges) $ 2,430 889 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 $600.3 million and $17.2 million in First Quarter 2017 and First Quarter 2016 , respectively. This increase was driven by higher trading volume in our fixed income securities portfolio related to the recent hiring of new external investment managers.

Indebtedness Indebtedness

Indebtedness Indebtedness	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	Indebtedness Our long-term debt balance has not changed since December 31, 2016 . However, on February 28, 2017 , Selective Insurance Company of America ("SICA") borrowed $64 million in short-term funds from the FHLBNY at an interest rate of 0.75% . This borrowing was repaid on March 21, 2017 . For detailed information on our indebtedness, see Note 10. "Indebtedness" in Item 8. "Financial Statements and Supplementary Data." of our 2016 Annual Report .

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Our financial assets are measured at fair value as disclosed on the Consolidated Balance Sheets. The fair values of our long-term debt have improved since December 31, 2016, but none by more than 5%. 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 2016 Annual Report . The following tables provide quantitative disclosures of our financial assets that were measured at fair value at March 31, 2017 and December 31, 2016 : March 31, 2017 Fair Value Measurements Using ($ in thousands) Assets Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) 1 Significant Other Observable Inputs (Level 2) 1 Significant Unobservable Inputs (Level 3) Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 88,338 46,150 42,188 — Foreign government 32,593 — 32,593 — Obligations of states and political subdivisions 1,287,166 — 1,287,166 — Corporate securities 1,828,126 — 1,828,126 — CLO and other ABS 678,435 — 678,435 — CMBS 263,756 — 263,756 — RMBS 688,591 — 688,591 — Total AFS fixed income securities 4,867,005 46,150 4,820,855 — AFS equity securities: Common stock 138,331 130,655 — 7,676 Preferred stock 16,587 16,587 — — Total AFS equity securities 154,918 147,242 — 7,676 Total AFS securities 5,021,923 193,392 4,820,855 7,676 Short-term investments 247,207 247,207 — — Total assets measured at fair value $ 5,269,130 440,599 4,820,855 7,676 December 31, 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 $ 77,333 27,520 49,813 — Foreign government 26,865 — 26,865 — Obligations of states and political subdivisions 1,379,593 — 1,379,593 — Corporate securities 1,997,753 — 1,997,753 — CLO and other ABS 528,960 — 528,960 — CMBS 256,842 — 256,842 — RMBS 525,194 — 525,194 — Total AFS fixed income securities 4,792,540 27,520 4,765,020 — AFS equity securities: Common stock 130,608 122,932 — 7,676 Preferred stock 16,145 16,145 — — Total AFS equity securities 146,753 139,077 — 7,676 Total AFS securities 4,939,293 166,597 4,765,020 7,676 Short-term investments 221,701 221,701 — — Total assets measured at fair value $ 5,160,994 388,298 4,765,020 7,676 1 There were no transfers of securities between Level 1 and Level 2. There were no changes in the fair value of securities measured using Level 3 inputs since December 31, 2016 . The following tables provide quantitative information regarding our financial assets and liabilities that were disclosed at fair value at March 31, 2017 and December 31, 2016 : March 31, 2017 Fair Value Measurements Using ($ in thousands) Assets/ Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets HTM: Obligations of states and political subdivisions $ 64,760 — 64,760 — Corporate securities 23,579 — 15,998 7,581 Total HTM fixed income securities $ 88,339 — 80,758 7,581 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 56,225 — 56,225 — 6.70% Senior Notes 108,553 — 108,553 — 5.875% Senior Notes 185,666 185,666 — — 1.61% borrowings from FHLBNY 24,393 — 24,393 — 1.56% borrowings from FHLBNY 24,329 — 24,329 — 3.03% borrowings from FHLBI 59,620 — 59,620 — Total long-term debt $ 458,786 185,666 273,120 — December 31, 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 $ 79,916 — 79,916 — Corporate securities 24,075 — 16,565 7,510 CMBS 1,220 — 1,220 — Total HTM fixed income securities $ 105,211 — 97,701 7,510 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 56,148 — 56,148 — 6.70% Senior Notes 108,333 — 108,333 — 5.875% Senior Notes 176,860 176,860 — — 1.61% borrowings from FHLBNY 24,286 — 24,286 — 1.56% borrowings from FHLBNY 24,219 — 24,219 — 3.03% borrowings from FHLBI 59,313 — 59,313 — Total long-term debt $ 449,159 176,860 272,299 —

Reinsurance

Reinsurance	3 Months Ended
	Mar. 31, 2017
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 2016 Annual Report . Quarter ended March 31, ($ in thousands) 2017 2016 Premiums written: Direct $ 683,820 646,278 Assumed 5,691 6,320 Ceded (90,807 ) (87,239 ) Net $ 598,704 565,359 Premiums earned: Direct $ 646,728 606,661 Assumed 5,779 6,270 Ceded (91,653 ) (90,473 ) Net $ 560,854 522,458 Loss and loss expense incurred: Direct $ 342,122 361,639 Assumed 4,437 6,355 Ceded (29,087 ) (70,850 ) Net $ 317,472 297,144 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 March 31, ($ in thousands) 2017 2016 Ceded premiums written $ (56,334 ) (53,248 ) Ceded premiums earned (57,277 ) (56,814 ) Ceded loss and loss expense incurred (6,541 ) (40,718 )

Reserve for Losses and Loss Exp

Reserve for Losses and Loss Expenses Reserves for Losses and Loss Expenses	3 Months Ended
	Mar. 31, 2017
Insurance Loss Reserves [Abstract]
Liability for Future Policy Benefits and Unpaid Claims Disclosure [Text Block]	Reserves for Losses and Loss Expenses The table below provides a roll forward of reserves for losses and loss expenses for beginning and ending reserve balances: Quarter ended March 31, ($ in thousands) 2017 2016 Gross reserves for losses and loss expenses, at beginning of year $ 3,691,719 3,517,728 Less: reinsurance recoverable on unpaid losses and loss expenses, at beginning of year 611,200 551,019 Net reserves for losses and loss expenses, at beginning of year 3,080,519 2,966,709 Incurred losses and loss expenses for claims occurring in the: Current year 331,331 312,778 Prior years (13,859 ) (15,634 ) Total incurred losses and loss expenses 317,472 297,144 Paid losses and loss expenses for claims occurring in the: Current year 54,708 44,310 Prior years 235,742 212,368 Total paid losses and loss expenses 290,450 256,678 Net reserves for losses and loss expenses, at end of period 3,107,541 3,007,175 Add: Reinsurance recoverable on unpaid losses and loss expenses, at end of period 571,930 568,321 Gross reserves for losses and loss expenses at end of period $ 3,679,471 3,575,496 Prior year development in First Quarter 2017 of $13.9 million was primarily driven by favorable prior year casualty reserve development of $22.4 million in our general liability line of business, partially offset by unfavorable casualty development of $6.0 million in our commercial automobile line of business and $2.0 million in our personal automobile line of business. Prior year development in First Quarter 2016 of $15.6 million was primarily due to favorable casualty reserve development of $12.0 million in our workers compensation line of business and $11.0 million in our general liability line of business. This was partially offset by unfavorable casualty development of $5.0 million in our commercial automobile line of business and $1.0 million in our E&S segment. For a discussion of the trends and recent developments impacting these lines, refer to the "Critical Accounting Policies and Estimates" section of Item 7. "Management's Discussion and Analysis of Financial Condition and Results of Operations." in our 2016 Annual Report.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information The disaggregated results of our four reportable segments are used by senior management to manage our operations. These reportable segments are evaluated as follows: • Our Standard Commercial Lines, Standard Personal Lines, and Excess and Surplus ("E&S") Lines are evaluated based on statutory underwriting results (net premiums earned, incurred losses and loss expenses, policyholder dividends, policy acquisition costs, and other underwriting expenses), and statutory combined ratios. • Our Investments segment is evaluated based on after-tax net investment income and net realized gains and losses. In computing the results of each segment, we do not make adjustments for interest expense or net general corporate expenses; however, we do partially allocate taxes to various segments. Furthermore, 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 March 31, ($ in thousands) 2017 2016 Standard Commercial Lines: Net premiums earned: Commercial automobile $ 107,129 95,419 Workers compensation 79,326 76,000 General liability 139,984 128,085 Commercial property 76,391 70,178 Businessowners’ policies 24,845 23,904 Bonds 6,498 5,464 Other 4,241 3,839 Miscellaneous income 2,860 690 Total Standard Commercial Lines revenue 441,274 403,579 Standard Personal Lines: Net premiums earned: Personal automobile 36,950 35,780 Homeowners 32,700 32,900 Other 1,551 1,525 Miscellaneous income 381 260 Total Standard Personal Lines revenue 71,582 70,465 E&S Lines: Net premiums earned: Commercial liability 37,912 36,856 Commercial property 13,327 12,508 Miscellaneous income — 1 Total E&S Lines revenue 51,239 49,365 Investments: Net investment income 37,419 30,769 Net realized investment losses (1,045 ) (2,704 ) Total Investments revenue 36,374 28,065 Total revenues $ 600,469 551,474 Income Before Federal Income Tax Quarter ended March 31, ($ in thousands) 2017 2016 Standard Commercial Lines: Underwriting gain $ 42,546 30,932 GAAP combined ratio 90.3 % 92.3 Statutory combined ratio 88.3 89.7 Standard Personal Lines: Underwriting gain $ 5,106 8,605 GAAP combined ratio 92.8 % 87.7 Statutory combined ratio 93.9 90.6 E&S Lines: Underwriting gain $ 1,570 1,418 GAAP combined ratio 96.9 % 97.1 Statutory combined ratio 95.9 98.4 Investments: Net investment income $ 37,419 30,769 Net realized investment losses (1,045 ) (2,704 ) Total investment income, before federal income tax 36,374 28,065 Tax on investment income 9,602 6,263 Total investment income, after federal income tax $ 26,772 21,802 Reconciliation of Segment Results to Income Before Federal Income Tax Quarter ended March 31, ($ in thousands) 2017 2016 Underwriting gain, before federal income tax Standard Commercial Lines $ 42,546 30,932 Standard Personal Lines 5,106 8,605 E&S Lines 1,570 1,418 Investment income, before federal income tax 36,374 28,065 Total all segments 85,596 69,020 Interest expense (6,106 ) (5,606 ) General corporate and other expenses (11,916 ) (11,539 ) Income, before federal income tax $ 67,574 51,875

Retirement Plans

Retirement Plans	3 Months Ended
	Mar. 31, 2017
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 2016 Annual Report . The following tables provide information regarding the Pension Plan: Pension Plan ($ in thousands) 2017 2016 Net Periodic Benefit Cost: Service cost $ — 1,606 Interest cost 3,111 3,102 Expected return on plan assets (4,854 ) (3,988 ) Amortization of unrecognized net actuarial loss 481 1,480 Total net periodic cost $ (1,262 ) 2,200 Pension Plan 2017 2016 Weighted-Average Expense Assumptions: Discount rate 4.41 % 4.69 % Effective interest rate for calculation of service cost n/a 4.52 Effective interest rate for calculation of interest cost 3.83 % 4.02 Expected return on plan assets 6.24 % 6.37 Rate of compensation increase n/a 4.00

Comprehensive Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2017
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 First Quarter 2017 and First Quarter 2016 are as follows: First Quarter 2017 ($ in thousands) Gross Tax Net Net income $ 67,574 17,134 50,440 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 25,785 9,024 16,761 Amounts reclassified into net income: HTM securities (49 ) (17 ) (32 ) Realized losses on AFS securities 1,510 529 981 Total unrealized gains on investment securities 27,246 9,536 17,710 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 507 177 330 Total defined benefit pension and post-retirement plans 507 177 330 Other comprehensive income 27,753 9,713 18,040 Comprehensive income $ 95,327 26,847 68,480 First Quarter 2016 ($ in thousands) Gross Tax Net Net income $ 51,875 14,843 37,032 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 65,737 23,008 42,729 Amounts reclassified into net income: HTM securities (72 ) (25 ) (47 ) Realized losses on AFS securities 2,699 945 1,754 Total unrealized gains on investment securities 68,364 23,928 44,436 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,516 530 986 Total defined benefit pension and post-retirement plans 1,516 530 986 Other comprehensive income 69,880 24,458 45,422 Comprehensive income $ 121,755 39,301 82,454 The balances of, and changes in, each component of AOCI (net of taxes) as of March 31, 2017 were as follows: March 31, 2017 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, 2016 $ (150 ) 102 42,170 42,122 (58,072 ) (15,950 ) OCI before reclassifications — — 16,761 16,761 — 16,761 Amounts reclassified from AOCI — (32 ) 981 949 330 1,279 Net current period OCI — (32 ) 17,742 17,710 330 18,040 Balance, March 31, 2017 $ (150 ) 70 59,912 59,832 (57,742 ) 2,090 The reclassifications out of AOCI were as follows: Quarter ended Affected Line Item in the Unaudited Consolidated Statement of Income ($ in thousands) 2017 2016 HTM related Unrealized losses on HTM disposals 13 28 Net realized losses Amortization of net unrealized gains on HTM securities (62 ) (100 ) Net investment income earned (49 ) (72 ) Income before federal income tax 17 25 Total federal income tax expense (32 ) (47 ) Net income Realized losses (gains) on AFS and OTTI Realized losses (gains) on AFS disposals and OTTI 1,510 2,699 Net realized losses 1,510 2,699 Income before federal income tax (529 ) (945 ) Total federal income tax expense 981 1,754 Net income Defined benefit pension and post-retirement life plans Net actuarial loss 110 329 Losses and loss expenses incurred 397 1,187 Policy acquisition costs Total defined benefit pension and post-retirement life 507 1,516 Income before federal income tax (177 ) (530 ) Total federal income tax expense 330 986 Net income Total reclassifications for the period $ 1,279 2,693 Net income

Related Party Transactions Rela

Related Party Transactions Related Party Transactions	3 Months Ended
	Mar. 31, 2017
Related Party Transaction [Line Items]
Related Party Transactions Disclosure [Text Block]	Related Party Transactions BlackRock, Inc., a leading publicly traded investment management firm, with $5.4 trillion of assets under management at March 31, 2017 (“BlackRock”), has purchased our common shares in the ordinary course of its investment business and has previously filed Schedules 13G/A with the SEC. On April 10, 2017 , BlackRock filed a Schedule 13G/A reporting beneficial ownership as of March 31, 2017 , of 12.7% of our common stock. In connection with purchasing our common shares, BlackRock filed the necessary filings with insurance regulatory authorities. On the basis of those filings, BlackRock is deemed not to be a controlling person for the purposes of applicable insurance law. We are required to disclose related party information for our transactions with BlackRock. BlackRock is highly regulated, serves its clients as a fiduciary, and has a diverse platform of active (alpha) and index (beta) investment strategies across asset classes that enables it to tailor investment outcomes and asset allocation solutions for clients. BlackRock also offers the BlackRock Solutions ® investment and risk management technology platform, Aladdin ® , risk analytics, advisory and technology services and solutions to a broad base of institutional and wealth management investors. In First Quarter 2017 , we incurred expenses related to BlackRock of $0.5 million for services rendered. No material expenses were incurred with BlackRock in First Quarter 2016 . Amounts payable for such services at March 31, 2017 and December 31, 2016 , were $0.8 million and $0.4 million , respectively. We have no additional material transactions with related parties other than those disclosed in Note 16. "Related Party Transactions" included in Item 8. "Financial Statements and Supplementary Data." of our 2016 Annual Report .

Litigation

Litigation	3 Months Ended
	Mar. 31, 2017
Loss Contingency, Information about Litigation Matters [Abstract]
Litigation	Litigation In the ordinary course of conducting business, we are named as defendants in various legal proceedings. Most of these proceedings are claims litigation involving our ten insurance subsidiaries ("Insurance Subsidiaries") as either: (i) liability insurers defending or providing indemnity for third-party claims brought against our customers; or (ii) insurers defending first-party coverage claims brought against them. We account for such activity through the establishment of unpaid losses and loss expense reserves. We expect that any potential ultimate liability in such ordinary course claims litigation will not be material to our consolidated financial condition, results of operations, or cash flows after consideration of provisions made for potential losses and costs of defense. From time to time, our Insurance Subsidiaries also are named as defendants in other legal actions, some of which assert claims for substantial amounts. These actions include, among others, putative class actions seeking certification of a state or national class. Such putative class actions have alleged, for example, improper reimbursement of medical providers paid under workers compensation and personal and commercial automobile insurance policies. Similarly, our Insurance Subsidiaries are also named from time-to-time in individual actions seeking extra-contractual damages, punitive damages, or penalties, some of which allege bad faith in the handling of insurance claims. We believe that we have valid defenses to these cases. We expect that any potential ultimate liability in any such lawsuit will not be material to our consolidated financial condition, after consideration of provisions made for estimated losses. Nonetheless, given the inherent unpredictability of litigation and the large or indeterminate amounts sought in certain of these actions, an adverse outcome in certain matters could possibly have a material adverse effect on our consolidated results of operations or cash flows in particular quarterly or annual periods. As of March 31, 2017 , 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.

Statements of Cash Flow (Tables

Statements of Cash Flow (Tables)	3 Months Ended
	Mar. 31, 2017
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Quarter ended March 31, ($ in thousands) 2017 2016 Cash paid during the period for: Interest $ 3,409 2,904 Federal income tax — 8,000 Non-cash items: Exchange of fixed income securities, AFS 1,029 9,872 Assets acquired under capital lease arrangements 278 2,598 Non-cash purchase of property and equipment — 152 1 Examples of such corporate actions include non-cash acquisitions and stock splits.

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2017
Investments [Line Items]
Schedule of Held-to-maturity Securities	March 31, 2017 ($ in thousands) Amortized Cost Net Unrealized Gains (Losses) Carrying Value Unrecognized Holding Gains Unrecognized Holding Losses Fair Value Obligations of states and political subdivisions $ 62,534 245 62,779 1,981 — 64,760 Corporate securities 22,194 (137 ) 22,057 1,614 (92 ) 23,579 Total HTM fixed income securities $ 84,728 108 84,836 3,595 (92 ) 88,339 December 31, 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 $ 77,466 317 77,783 2,133 — 79,916 Corporate securities 22,711 (143 ) 22,568 1,665 (158 ) 24,075 Commercial mortgage-backed securities ("CMBS") 1,220 (15 ) 1,205 15 — 1,220 Total HTM fixed income securities $ 101,397 159 101,556 3,813 (158 ) 105,211
Schedule of Available-for-sale Securities	March 31, 2017 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 86,816 1,566 (44 ) 88,338 Foreign government 31,965 628 — 32,593 Obligations of states and political subdivisions 1,261,191 28,923 (2,948 ) 1,287,166 Corporate securities 1,799,706 30,493 (2,073 ) 1,828,126 Collateralized loan obligations and other asset-backed securities ("CLO and other ABS") 675,838 2,998 (401 ) 678,435 CMBS 263,217 1,314 (775 ) 263,756 Residential mortgage-backed securities (“RMBS”) 686,635 3,623 (1,667 ) 688,591 Total AFS fixed income securities 4,805,368 69,545 (7,908 ) 4,867,005 AFS equity securities: Common stock 108,466 30,150 (285 ) 138,331 Preferred stock 16,148 480 (41 ) 16,587 Total AFS equity securities 124,614 30,630 (326 ) 154,918 Total AFS securities $ 4,929,982 100,175 (8,234 ) 5,021,923 December 31, 2016 ($ in thousands) Cost/ Amortized Cost Unrealized Gains Unrealized Losses Fair Value AFS fixed income securities: U.S. government and government agencies $ 75,139 2,230 (36 ) 77,333 Foreign government 26,559 322 (16 ) 26,865 Obligations of states and political subdivisions 1,366,287 18,610 (5,304 ) 1,379,593 Corporate securities 1,976,556 27,057 (5,860 ) 1,997,753 CLO and other ABS 527,876 1,439 (355 ) 528,960 CMBS 256,356 1,514 (1,028 ) 256,842 RMBS 524,986 3,006 (2,798 ) 525,194 Total AFS fixed income securities 4,753,759 54,178 (15,397 ) 4,792,540 AFS equity securities: Common stock 104,663 26,250 (305 ) 130,608 Preferred stock 16,226 274 (355 ) 16,145 Total AFS equity securities 120,889 26,524 (660 ) 146,753 Total AFS securities $ 4,874,648 80,702 (16,057 ) 4,939,293
Schedule of The Number Of Securities In An Unrealized Unrecognized Loss Position	($ in thousands) March 31, 2017 December 31, 2016 Number of Issues % of Market/Book Unrealized/ Unrecognized Loss Number of Issues % of Market/Book Unrealized/ Unrecognized Loss 304 80% - 99% $ 8,326 456 80% - 99% $ 16,215 — 60% - 79% — — 60% - 79% — — 40% - 59% — — 40% - 59% — — 20% - 39% — — 20% - 39% — — 0% - 19% — — 0% - 19% — $ 8,326 $ 16,215
Schedule of Fair Value and Gross Pre-Tax Net Unrealized/Unrecognized Loss of Securities by Length of Time	March 31, 2017 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 Fair Value Unrealized 1 AFS fixed income securities: U.S. government and government agencies $ 9,012 (44 ) — — 9,012 (44 ) Obligations of states and political subdivisions 114,632 (2,948 ) — — 114,632 (2,948 ) Corporate securities 229,836 (2,068 ) 244 (5 ) 230,080 (2,073 ) CLO and other ABS 137,388 (400 ) 310 (1 ) 137,698 (401 ) CMBS 80,494 (775 ) — — 80,494 (775 ) RMBS 212,486 (1,588 ) 2,246 (79 ) 214,732 (1,667 ) Total AFS fixed income securities 783,848 (7,823 ) 2,800 (85 ) 786,648 (7,908 ) AFS equity securities: Common stock 10,088 (285 ) — — 10,088 (285 ) Preferred stock 1,527 (41 ) — — 1,527 (41 ) Total AFS equity securities 11,615 (326 ) — — 11,615 (326 ) Total AFS $ 795,463 (8,149 ) 2,800 (85 ) 798,263 (8,234 ) December 31, 2016 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Losses 1 Fair Value Unrealized Losses 1 Fair Value Unrealized 1 AFS fixed income securities: U.S. government and government agencies $ 6,419 (36 ) — — 6,419 (36 ) Foreign government 13,075 (16 ) — — 13,075 (16 ) Obligations of states and political subdivisions 306,509 (5,304 ) — — 306,509 (5,304 ) Corporate securities 462,902 (5,771 ) 4,913 (89 ) 467,815 (5,860 ) CLO and other ABS 189,795 (354 ) 319 (1 ) 190,114 (355 ) CMBS 82,492 (1,021 ) 1,645 (7 ) 84,137 (1,028 ) RMBS 279,480 (2,489 ) 8,749 (309 ) 288,229 (2,798 ) Total AFS fixed income securities 1,340,672 (14,991 ) 15,626 (406 ) 1,356,298 (15,397 ) AFS equity securities: Common stock 11,271 (305 ) — — 11,271 (305 ) Preferred stock 6,168 (355 ) — — 6,168 (355 ) Total AFS equity securities 17,439 (660 ) — — 17,439 (660 ) Total AFS $ 1,358,111 (15,651 ) 15,626 (406 ) 1,373,737 (16,057 ) 1 Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI.
Schedule of Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy	Other Investments March 31, 2017 December 31, 2016 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Carrying Value Remaining Commitment Maximum Exposure to Loss 1 Alternative Investments Private equity $ 41,354 74,669 116,023 41,135 76,774 117,909 Private credit 31,026 40,745 71,771 28,193 40,613 68,806 Real assets 16,265 27,764 44,029 14,486 22,899 37,385 Total alternative investments 88,645 143,178 231,823 83,814 140,286 224,100 Other securities 18,151 267 18,418 18,583 3,400 21,983 Total other investments $ 106,796 143,445 250,241 102,397 143,686 246,083 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 December 31, ($ in millions) 2016 2015 Net investment (loss) income $ 25.6 46.6 Realized gains (235.1 ) 752.5 Net change in unrealized depreciation 561.5 (883.2 ) Net gain $ 352.0 (84.1 ) Selective’s insurance subsidiaries’ other investments gain (loss) $ 1.6 (1.1 )
Schedule of Securities Pledged As Collateral	($ in millions) FHLBI Collateral FHLBNY Collateral State and Regulatory Deposits Total U.S. government and government agencies $ 4.3 — 24.4 28.7 CMBS 3.6 4.8 — 8.4 RMBS 60.4 53.9 — 114.3 Total pledged as collateral $ 68.3 58.7 24.4 151.4
Schedule of Net Investment Income Earned	Quarter ended March 31, ($ in thousands) 2017 2016 Fixed income securities $ 36,891 31,644 Equity securities 1,468 2,230 Short-term investments 250 159 Other investments 1,603 (1,066 ) Investment expenses (2,793 ) (2,198 ) Net investment income earned $ 37,419 30,769
Schedule of OTTI By Asset Type	First Quarter 2017 Gross Included in Other Comprehensive Income ("OCI") Recognized in ($ in thousands) AFS fixed income securities: U.S. government and government agencies 29 — 29 Obligations of states and political subdivisions 373 — 373 Corporate securities 194 — 194 CLO and other ABS 23 — 23 CMBS 450 — 450 RMBS 1,092 — 1,092 Total AFS fixed income securities 2,161 — 2,161 AFS equity securities: Common stock $ 1,314 — 1,314 Total AFS equity securities 1,314 — 1,314 Total OTTI losses $ 3,475 — 3,475 First Quarter 2016 Gross Included in OCI Recognized in ($ in thousands) AFS fixed income securities: Corporate securities $ 973 — 973 Total AFS fixed income securities 973 — 973 AFS equity securities: Common stock 2,617 — 2,617 Preferred stock 3 — 3 Total AFS equity securities 2,620 — 2,620 Total OTTI losses $ 3,593 — 3,593
Schedule of Components of Net Realized Gains Excluding OTTI Charges	Quarter ended March 31, ($ in thousands) 2017 2016 HTM fixed income securities Gains $ — — Losses (1 ) (1 ) AFS fixed income securities Gains 3,552 620 Losses (1,587 ) (36 ) AFS equity securities Gains — 330 Losses — (20 ) Other investments Gains 480 — Losses (14 ) (4 ) Total net realized gains (excluding OTTI charges) $ 2,430 889
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 $ 39,376 39,876 Due after one year through five years 37,028 39,365 Due after five years through 10 years 8,432 9,098 Total HTM fixed income securities $ 84,836 88,339
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 $ 331,997 Due after one year through five years 1,989,887 Due after five years through 10 years 2,294,091 Due after 10 years 251,030 Total AFS fixed income securities $ 4,867,005

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Schedule of Quantitative Disclosures of Our Financial Assets That Were Measured At Fair Value	March 31, 2017 Fair Value Measurements Using ($ in thousands) Assets Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) 1 Significant Other Observable Inputs (Level 2) 1 Significant Unobservable Inputs (Level 3) Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 88,338 46,150 42,188 — Foreign government 32,593 — 32,593 — Obligations of states and political subdivisions 1,287,166 — 1,287,166 — Corporate securities 1,828,126 — 1,828,126 — CLO and other ABS 678,435 — 678,435 — CMBS 263,756 — 263,756 — RMBS 688,591 — 688,591 — Total AFS fixed income securities 4,867,005 46,150 4,820,855 — AFS equity securities: Common stock 138,331 130,655 — 7,676 Preferred stock 16,587 16,587 — — Total AFS equity securities 154,918 147,242 — 7,676 Total AFS securities 5,021,923 193,392 4,820,855 7,676 Short-term investments 247,207 247,207 — — Total assets measured at fair value $ 5,269,130 440,599 4,820,855 7,676 December 31, 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 $ 77,333 27,520 49,813 — Foreign government 26,865 — 26,865 — Obligations of states and political subdivisions 1,379,593 — 1,379,593 — Corporate securities 1,997,753 — 1,997,753 — CLO and other ABS 528,960 — 528,960 — CMBS 256,842 — 256,842 — RMBS 525,194 — 525,194 — Total AFS fixed income securities 4,792,540 27,520 4,765,020 — AFS equity securities: Common stock 130,608 122,932 — 7,676 Preferred stock 16,145 16,145 — — Total AFS equity securities 146,753 139,077 — 7,676 Total AFS securities 4,939,293 166,597 4,765,020 7,676 Short-term investments 221,701 221,701 — — Total assets measured at fair value $ 5,160,994 388,298 4,765,020 7,676 1 There were no transfers of securities between Level 1 and Level 2.
Schedule of Quantitative Information of Our Financial Assets and Liabilities That Were Disclosed at Fair Value	March 31, 2017 Fair Value Measurements Using ($ in thousands) Assets/ Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets HTM: Obligations of states and political subdivisions $ 64,760 — 64,760 — Corporate securities 23,579 — 15,998 7,581 Total HTM fixed income securities $ 88,339 — 80,758 7,581 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 56,225 — 56,225 — 6.70% Senior Notes 108,553 — 108,553 — 5.875% Senior Notes 185,666 185,666 — — 1.61% borrowings from FHLBNY 24,393 — 24,393 — 1.56% borrowings from FHLBNY 24,329 — 24,329 — 3.03% borrowings from FHLBI 59,620 — 59,620 — Total long-term debt $ 458,786 185,666 273,120 — December 31, 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 $ 79,916 — 79,916 — Corporate securities 24,075 — 16,565 7,510 CMBS 1,220 — 1,220 — Total HTM fixed income securities $ 105,211 — 97,701 7,510 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 56,148 — 56,148 — 6.70% Senior Notes 108,333 — 108,333 — 5.875% Senior Notes 176,860 176,860 — — 1.61% borrowings from FHLBNY 24,286 — 24,286 — 1.56% borrowings from FHLBNY 24,219 — 24,219 — 3.03% borrowings from FHLBI 59,313 — 59,313 — Total long-term debt $ 449,159 176,860 272,299 —

Reinsurance (Tables)

Reinsurance (Tables)	3 Months Ended
	Mar. 31, 2017
Reinsurance Disclosures [Abstract]
Schedule of List Of Direct, Assumed, And Ceded Reinsurance Amounts	Quarter ended March 31, ($ in thousands) 2017 2016 Premiums written: Direct $ 683,820 646,278 Assumed 5,691 6,320 Ceded (90,807 ) (87,239 ) Net $ 598,704 565,359 Premiums earned: Direct $ 646,728 606,661 Assumed 5,779 6,270 Ceded (91,653 ) (90,473 ) Net $ 560,854 522,458 Loss and loss expense incurred: Direct $ 342,122 361,639 Assumed 4,437 6,355 Ceded (29,087 ) (70,850 ) Net $ 317,472 297,144
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 March 31, ($ in thousands) 2017 2016 Ceded premiums written $ (56,334 ) (53,248 ) Ceded premiums earned (57,277 ) (56,814 ) Ceded loss and loss expense incurred (6,541 ) (40,718 )

Reserve for Losses and Loss E26

Reserve for Losses and Loss Expenses Reserves for Losses and Loss Expenses (Tables)	3 Months Ended
	Mar. 31, 2017
Insurance Loss Reserves [Abstract]
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block]	Quarter ended March 31, ($ in thousands) 2017 2016 Gross reserves for losses and loss expenses, at beginning of year $ 3,691,719 3,517,728 Less: reinsurance recoverable on unpaid losses and loss expenses, at beginning of year 611,200 551,019 Net reserves for losses and loss expenses, at beginning of year 3,080,519 2,966,709 Incurred losses and loss expenses for claims occurring in the: Current year 331,331 312,778 Prior years (13,859 ) (15,634 ) Total incurred losses and loss expenses 317,472 297,144 Paid losses and loss expenses for claims occurring in the: Current year 54,708 44,310 Prior years 235,742 212,368 Total paid losses and loss expenses 290,450 256,678 Net reserves for losses and loss expenses, at end of period 3,107,541 3,007,175 Add: Reinsurance recoverable on unpaid losses and loss expenses, at end of period 571,930 568,321 Gross reserves for losses and loss expenses at end of period $ 3,679,471 3,575,496 Prior year development in First Quarter 2017 of $13.9 million was primarily driven by favorable prior year casualty reserve development of $22.4 million in our general liability line of business, partially offset by unfavorable casualty development of $6.0 million in our commercial automobile line of business and $2.0 million in our personal automobile line of business. Prior year development in First Quarter 2016 of $15.6 million was primarily due to favorable casualty reserve development of $12.0 million in our workers compensation line of business and $11.0 million in our general liability line of business. This was partially offset by unfavorable casualty development of $5.0 million in our commercial automobile line of business and $1.0 million in our E&S segment. For a discussion of the trends and recent developments impacting these lines, refer to the "Critical Accounting Policies and Estimates" section of Item 7. "Management's Discussion and Analysis of Financial Condition and Results of Operations." in our 2016 Annual Report.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Schedule of Revenue By Segment	Revenue by Segment Quarter ended March 31, ($ in thousands) 2017 2016 Standard Commercial Lines: Net premiums earned: Commercial automobile $ 107,129 95,419 Workers compensation 79,326 76,000 General liability 139,984 128,085 Commercial property 76,391 70,178 Businessowners’ policies 24,845 23,904 Bonds 6,498 5,464 Other 4,241 3,839 Miscellaneous income 2,860 690 Total Standard Commercial Lines revenue 441,274 403,579 Standard Personal Lines: Net premiums earned: Personal automobile 36,950 35,780 Homeowners 32,700 32,900 Other 1,551 1,525 Miscellaneous income 381 260 Total Standard Personal Lines revenue 71,582 70,465 E&S Lines: Net premiums earned: Commercial liability 37,912 36,856 Commercial property 13,327 12,508 Miscellaneous income — 1 Total E&S Lines revenue 51,239 49,365 Investments: Net investment income 37,419 30,769 Net realized investment losses (1,045 ) (2,704 ) Total Investments revenue 36,374 28,065 Total revenues $ 600,469 551,474 Income Before Federal Income Tax Quarter ended March 31, ($ in thousands) 2017 2016 Standard Commercial Lines: Underwriting gain $ 42,546 30,932 GAAP combined ratio 90.3 % 92.3 Statutory combined ratio 88.3 89.7 Standard Personal Lines: Underwriting gain $ 5,106 8,605 GAAP combined ratio 92.8 % 87.7 Statutory combined ratio 93.9 90.6 E&S Lines: Underwriting gain $ 1,570 1,418 GAAP combined ratio 96.9 % 97.1 Statutory combined ratio 95.9 98.4 Investments: Net investment income $ 37,419 30,769 Net realized investment losses (1,045 ) (2,704 ) Total investment income, before federal income tax 36,374 28,065 Tax on investment income 9,602 6,263 Total investment income, after federal income tax $ 26,772 21,802
Schedule of Income Before Federal Income Tax	Income Before Federal Income Tax Quarter ended March 31, ($ in thousands) 2017 2016 Standard Commercial Lines: Underwriting gain $ 42,546 30,932 GAAP combined ratio 90.3 % 92.3 Statutory combined ratio 88.3 89.7 Standard Personal Lines: Underwriting gain $ 5,106 8,605 GAAP combined ratio 92.8 % 87.7 Statutory combined ratio 93.9 90.6 E&S Lines: Underwriting gain $ 1,570 1,418 GAAP combined ratio 96.9 % 97.1 Statutory combined ratio 95.9 98.4 Investments: Net investment income $ 37,419 30,769 Net realized investment losses (1,045 ) (2,704 ) Total investment income, before federal income tax 36,374 28,065 Tax on investment income 9,602 6,263 Total investment income, after federal income tax $ 26,772 21,802
Schedule of Reconciliation of Segment Results to Income Before Federal Income Tax	Reconciliation of Segment Results to Income Before Federal Income Tax Quarter ended March 31, ($ in thousands) 2017 2016 Underwriting gain, before federal income tax Standard Commercial Lines $ 42,546 30,932 Standard Personal Lines 5,106 8,605 E&S Lines 1,570 1,418 Investment income, before federal income tax 36,374 28,065 Total all segments 85,596 69,020 Interest expense (6,106 ) (5,606 ) General corporate and other expenses (11,916 ) (11,539 ) Income, before federal income tax $ 67,574 51,875

Retirement Plans (Table)

Retirement Plans (Table)	3 Months Ended
	Mar. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Schedule of Components of Net Periodic Benefit Cost	Pension Plan ($ in thousands) 2017 2016 Net Periodic Benefit Cost: Service cost $ — 1,606 Interest cost 3,111 3,102 Expected return on plan assets (4,854 ) (3,988 ) Amortization of unrecognized net actuarial loss 481 1,480 Total net periodic cost $ (1,262 ) 2,200 Pension Plan 2017 2016 Weighted-Average Expense Assumptions: Discount rate 4.41 % 4.69 % Effective interest rate for calculation of service cost n/a 4.52 Effective interest rate for calculation of interest cost 3.83 % 4.02 Expected return on plan assets 6.24 % 6.37 Rate of compensation increase n/a 4.00
Schedule of Weighted-Average Expense Assumptions	Pension Plan 2017 2016 Weighted-Average Expense Assumptions: Discount rate 4.41 % 4.69 % Effective interest rate for calculation of service cost n/a 4.52 Effective interest rate for calculation of interest cost 3.83 % 4.02 Expected return on plan assets 6.24 % 6.37 Rate of compensation increase n/a 4.00

Comprehensive Income (Tables)

Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2017
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Schedule of Components of Comprehensive Income-Gross and Net of Tax	First Quarter 2017 ($ in thousands) Gross Tax Net Net income $ 67,574 17,134 50,440 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 25,785 9,024 16,761 Amounts reclassified into net income: HTM securities (49 ) (17 ) (32 ) Realized losses on AFS securities 1,510 529 981 Total unrealized gains on investment securities 27,246 9,536 17,710 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 507 177 330 Total defined benefit pension and post-retirement plans 507 177 330 Other comprehensive income 27,753 9,713 18,040 Comprehensive income $ 95,327 26,847 68,480 First Quarter 2016 ($ in thousands) Gross Tax Net Net income $ 51,875 14,843 37,032 Components of OCI: Unrealized gains on investment securities : Unrealized holding gains during period 65,737 23,008 42,729 Amounts reclassified into net income: HTM securities (72 ) (25 ) (47 ) Realized losses on AFS securities 2,699 945 1,754 Total unrealized gains on investment securities 68,364 23,928 44,436 Defined benefit pension and post-retirement plans: Amounts reclassified into net income: Net actuarial loss 1,516 530 986 Total defined benefit pension and post-retirement plans 1,516 530 986 Other comprehensive income 69,880 24,458 45,422 Comprehensive income $ 121,755 39,301 82,454
Schedule of Components of Accumulated Other Comprehensive Income	March 31, 2017 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, 2016 $ (150 ) 102 42,170 42,122 (58,072 ) (15,950 ) OCI before reclassifications — — 16,761 16,761 — 16,761 Amounts reclassified from AOCI — (32 ) 981 949 330 1,279 Net current period OCI — (32 ) 17,742 17,710 330 18,040 Balance, March 31, 2017 $ (150 ) 70 59,912 59,832 (57,742 ) 2,090
Schedule of Reclassifications Out Of Accumulated Other Comprehensive Income	Quarter ended Affected Line Item in the Unaudited Consolidated Statement of Income ($ in thousands) 2017 2016 HTM related Unrealized losses on HTM disposals 13 28 Net realized losses Amortization of net unrealized gains on HTM securities (62 ) (100 ) Net investment income earned (49 ) (72 ) Income before federal income tax 17 25 Total federal income tax expense (32 ) (47 ) Net income Realized losses (gains) on AFS and OTTI Realized losses (gains) on AFS disposals and OTTI 1,510 2,699 Net realized losses 1,510 2,699 Income before federal income tax (529 ) (945 ) Total federal income tax expense 981 1,754 Net income Defined benefit pension and post-retirement life plans Net actuarial loss 110 329 Losses and loss expenses incurred 397 1,187 Policy acquisition costs Total defined benefit pension and post-retirement life 507 1,516 Income before federal income tax (177 ) (530 ) Total federal income tax expense 330 986 Net income Total reclassifications for the period $ 1,279 2,693 Net income

Statements of Cash Flow (Cash F

Statements of Cash Flow (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Interest	$ 3,409	$ 2,904
Federal income tax	0	8,000
Assets acquired under capital lease arrangements	278	2,598
Non-cash purchase of property and equipment	0	152
AFS Fixed Maturity Securities [Member]
Exchange of fixed income securities	1,029	9,872
National Flood Insurance Program [Member]
Restricted cash	$ 14,400	$ 13,500

Investments (Held-To-Maturity S

Investments (Held-To-Maturity Securities Disclosure) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 84,728	$ 101,397
Net Unrealized Gains (Losses)	108	159
Carrying Value	84,836	101,556
Unrecognized Holding Gains	3,595	3,813
Unrecognized Holding Losses	(92)	(158)
Held-to-maturity Securities, Fair Value	88,339	105,211
Obligations of States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	62,534	77,466
Net Unrealized Gains (Losses)	245	317
Carrying Value	62,779	77,783
Unrecognized Holding Gains	1,981	2,133
Unrecognized Holding Losses	0	0
Held-to-maturity Securities, Fair Value	64,760	79,916
Corporate Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	22,194	22,711
Net Unrealized Gains (Losses)	(137)	(143)
Carrying Value	22,057	22,568
Unrecognized Holding Gains	1,614	1,665
Unrecognized Holding Losses	(92)	(158)
Held-to-maturity Securities, Fair Value	$ 23,579	24,075
Commercial Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost		1,220
Net Unrealized Gains (Losses)		(15)
Carrying Value		1,205
Unrecognized Holding Gains		15
Unrecognized Holding Losses		0
Held-to-maturity Securities, Fair Value		$ 1,220

Investments (Available-For-Sale

Investments (Available-For-Sale Securities Disclosure) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	$ 4,929,982	$ 4,874,648
Unrealized Gains	100,175	80,702
Unrealized Losses	(8,234)	(16,057)
Total AFS securities	5,021,923	4,939,293
AFS Fixed Income Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	4,805,368	4,753,759
Unrealized Gains	69,545	54,178
Unrealized Losses	(7,908)	(15,397)
Total AFS securities	4,867,005	4,792,540
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	86,816	75,139
Unrealized Gains	1,566	2,230
Unrealized Losses	(44)	(36)
Total AFS securities	88,338	77,333
AFS Fixed Income Securities [Member] | Foreign Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	31,965	26,559
Unrealized Gains	628	322
Unrealized Losses	0	(16)
Total AFS securities	32,593	26,865
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	1,261,191	1,366,287
Unrealized Gains	28,923	18,610
Unrealized Losses	(2,948)	(5,304)
Total AFS securities	1,287,166	1,379,593
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	1,799,706	1,976,556
Unrealized Gains	30,493	27,057
Unrealized Losses	(2,073)	(5,860)
Total AFS securities	1,828,126	1,997,753
AFS Fixed Income Securities [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	675,838	527,876
Unrealized Gains	2,998	1,439
Unrealized Losses	(401)	(355)
Total AFS securities	678,435	528,960
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	263,217	256,356
Unrealized Gains	1,314	1,514
Unrealized Losses	(775)	(1,028)
Total AFS securities	263,756	256,842
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	686,635	524,986
Unrealized Gains	3,623	3,006
Unrealized Losses	(1,667)	(2,798)
Total AFS securities	688,591	525,194
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	124,614	120,889
Unrealized Gains	30,630	26,524
Unrealized Losses	(326)	(660)
Total AFS securities	154,918	146,753
Equity Securities [Member] | Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	108,466	104,663
Unrealized Gains	30,150	26,250
Unrealized Losses	(285)	(305)
Total AFS securities	138,331	130,608
Equity Securities [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost/Amortized Cost	16,148	16,226
Unrealized Gains	480	274
Unrealized Losses	(41)	(355)
Total AFS securities	$ 16,587	$ 16,145

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		Mar. 31, 2017	Dec. 31, 2016
AFS Fair Value, Less than 12 months		$ 795,463	$ 1,358,111
AFS Unrealized Losses, Less than 12 months	[1]	(8,149)	(15,651)
AFS Fair Value, 12 months or longer		2,800	15,626
AFS Unrealized Losses, 12 months or longer	[1]	(85)	(406)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		798,263	1,373,737
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(8,234)	(16,057)
AFS Fixed Income Securities [Member]
AFS Fair Value, Less than 12 months		783,848	1,340,672
AFS Unrealized Losses, Less than 12 months	[1]	(7,823)	(14,991)
AFS Fair Value, 12 months or longer		2,800	15,626
AFS Unrealized Losses, 12 months or longer	[1]	(85)	(406)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		786,648	1,356,298
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(7,908)	(15,397)
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member]
AFS Fair Value, Less than 12 months		9,012	6,419
AFS Unrealized Losses, Less than 12 months	[1]	(44)	(36)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		9,012	6,419
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(44)	(36)
AFS Fixed Income Securities [Member] | Foreign Government [Member]
AFS Fair Value, Less than 12 months			13,075
AFS Unrealized Losses, Less than 12 months	[1]		(16)
AFS Fair Value, 12 months or longer			0
AFS Unrealized Losses, 12 months or longer	[1]		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value			13,075
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]		(16)
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
AFS Fair Value, Less than 12 months		114,632	306,509
AFS Unrealized Losses, Less than 12 months	[1]	(2,948)	(5,304)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		114,632	306,509
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(2,948)	(5,304)
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
AFS Fair Value, Less than 12 months		229,836	462,902
AFS Unrealized Losses, Less than 12 months	[1]	(2,068)	(5,771)
AFS Fair Value, 12 months or longer		244	4,913
AFS Unrealized Losses, 12 months or longer	[1]	(5)	(89)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		230,080	467,815
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(2,073)	(5,860)
AFS Fixed Income Securities [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member]
AFS Fair Value, Less than 12 months		137,388	189,795
AFS Unrealized Losses, Less than 12 months	[1]	(400)	(354)
AFS Fair Value, 12 months or longer		310	319
AFS Unrealized Losses, 12 months or longer	[1]	(1)	(1)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		137,698	190,114
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(401)	(355)
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
AFS Fair Value, Less than 12 months		80,494	82,492
AFS Unrealized Losses, Less than 12 months	[1]	(775)	(1,021)
AFS Fair Value, 12 months or longer		0	1,645
AFS Unrealized Losses, 12 months or longer	[1]	0	(7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		80,494	84,137
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(775)	(1,028)
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
AFS Fair Value, Less than 12 months		212,486	279,480
AFS Unrealized Losses, Less than 12 months	[1]	(1,588)	(2,489)
AFS Fair Value, 12 months or longer		2,246	8,749
AFS Unrealized Losses, 12 months or longer	[1]	(79)	(309)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		214,732	288,229
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(1,667)	(2,798)
Equity Securities [Member]
AFS Fair Value, Less than 12 months		11,615	17,439
AFS Unrealized Losses, Less than 12 months	[1]	(326)	(660)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		11,615	17,439
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(326)	(660)
Equity Securities [Member] | Common Stock [Member]
AFS Fair Value, Less than 12 months		10,088	11,271
AFS Unrealized Losses, Less than 12 months	[1]	(285)	(305)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		10,088	11,271
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	(285)	(305)
Equity Securities [Member] | Preferred Stock [Member]
AFS Fair Value, Less than 12 months		1,527	6,168
AFS Unrealized Losses, Less than 12 months	[1]	(41)	(355)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		1,527	6,168
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	$ (41)	$ (355)
[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	Mar. 31, 2017USD ($)Securities	Dec. 31, 2016USD ($)Securities
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Unrealized Unrecognized Loss	$ 8,326	$ 16,215
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	304	456
Unrealized Unrecognized Loss	$ 8,326	$ 16,215
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	0
Unrealized Unrecognized Loss	$ 0	$ 0
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
Held-to-maturity Securities [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Unrealized Unrecognized Loss	$ 100	$ 200

Investments (HTM Fixed Income S

Investments (HTM Fixed Income Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Due in one year or less carrying value	$ 39,376
Due after one year through five years carrying value	37,028
Due after five years through 10 years carrying value	8,432
Carrying Value	84,836	$ 101,556
Due in one year or less fair value	39,876
Due after one year through five years fair value	39,365
Due after five years through 10 years fair value	9,098
HTM, Fair Value	$ 88,339	$ 105,211

Investments (AFS Fixed Income s

Investments (AFS Fixed Income securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less fair value	$ 331,997
Due after one year through five years fair value	1,989,887
Due after five years through 10 years fair value	2,294,091
Due after 10 years fair value	251,030
Total AFS fixed income securities	$ 4,867,005	$ 4,792,540

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		Mar. 31, 2017	Dec. 31, 2016
Carrying Value		$ 106,796	$ 102,397
Other Investments [Member]
Carrying Value		106,796	102,397
Remaining Commitment		143,445	143,686
Maximum Exposure to Loss	[1]	250,241	246,083
Alternative Investments [Member]
Carrying Value		88,645	83,814
Remaining Commitment		143,178	140,286
Maximum Exposure to Loss	[1]	231,823	224,100
Private Equity [Member] | Alternative Investments [Member]
Carrying Value		41,354	41,135
Remaining Commitment		74,669	76,774
Maximum Exposure to Loss	[1]	116,023	117,909
Private Credit [Member] | Alternative Investments [Member]
Carrying Value		31,026	28,193
Remaining Commitment		40,745	40,613
Maximum Exposure to Loss	[1]	71,771	68,806
Real Assets [Member] | Alternative Investments [Member]
Carrying Value		16,265	14,486
Remaining Commitment		27,764	22,899
Maximum Exposure to Loss	[1]	44,029	37,385
Other Securities [Member]
Carrying Value		18,151	18,583
Remaining Commitment		267	3,400
Maximum Exposure to Loss	[1]	$ 18,418	$ 21,983
[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
	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Net investment income earned	$ 37,419		$ 30,769
Alternative Investments [Member]
Schedule of Equity Method Investments [Line Items]
Net investment income earned	$ 1,600		$ (1,100)
Investments accounted for under the equity method [Member]
Schedule of Equity Method Investments [Line Items]
Net investment (loss) income		$ 25,600		$ 46,600
Realized gains		(235,100)		752,500
Net change in unrealized depreciation		561,500		(883,200)
Net gain		$ 352,000		$ (84,100)

Investments (Investments Pledge

Investments (Investments Pledged as Collateral) (Details) $ in Millions	Mar. 31, 2017USD ($)
Investments Pledged As Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	$ 24.4
Securities Pledged As Collateral	151.4
U.S. Government and Government Agencies [Member]
Investments Pledged As Collateral [Line Items]
Carrying Value Bonds On Deposit With Various State And Regulatory Agencies	24.4
Securities Pledged As Collateral	28.7
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	8.4
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	114.3
Federal Home Loan Bank of Indianapolis [Member]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	68.3
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	4.3
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	3.6
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	60.4
Federal Home Loan Bank of New York [Member]
Investments Pledged As Collateral [Line Items]
Fixed Income Securities Pledged For FHLB Collateral	58.7
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	4.8
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	$ 53.9

Investments (Credit Concentrati

Investments (Credit Concentration Risk) (Details)	Mar. 31, 2017	Dec. 31, 2016
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
	Mar. 31, 2017	Mar. 31, 2016
Net Investment Income [Line Items]
Net investment income earned	$ 37,419	$ 30,769
Fixed Income Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	36,891	31,644
Equity Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	1,468	2,230
Short-Term Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	250	159
Other Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	1,603	(1,066)
Investment Expenses [Member]
Net Investment Income [Line Items]
Net investment income earned	$ (2,793)	$ (2,198)

Investments (OTTI by Asset Type

Investments (OTTI by Asset Type) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
OTTI Losses Gross	$ 3,475	$ 3,593
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0
OTTI Losses Recognized in Earnings	3,475	3,593
US Treasury and Government [Member]
OTTI Losses Gross	29
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0
OTTI Losses Recognized in Earnings	29
Obligations of States and Political Subdivisions [Member]
OTTI Losses Gross	373
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0
OTTI Losses Recognized in Earnings	373
Collateralized Loan Obligations and Other Asset Backed Securities [Member]
OTTI Losses Gross	23
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0
OTTI Losses Recognized in Earnings	23
Commercial Mortgage Backed Securities [Member]
OTTI Losses Gross	450
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0
OTTI Losses Recognized in Earnings	450
AFS Fixed Income Securities [Member]
OTTI Losses Gross	2,161	973
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0
OTTI Losses Recognized in Earnings	2,161	973
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
OTTI Losses Gross	194	973
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0
OTTI Losses Recognized in Earnings	194	973
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
OTTI Losses Gross	1,092
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0
OTTI Losses Recognized in Earnings	1,092
Total AFS Securities [Member] | Equity Securities [Member]
OTTI Losses Gross	1,314	2,620
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0
OTTI Losses Recognized in Earnings	1,314	2,620
Common Stock [Member] | Total AFS Securities [Member] | Equity Securities [Member]
OTTI Losses Gross	1,314	2,617
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income	0	0
OTTI Losses Recognized in Earnings	$ 1,314	2,617
Preferred Stock [Member] | Total AFS Securities [Member] | Equity Securities [Member]
OTTI Losses Gross		3
Other-than-temporary impairments on fixed income securities recognized in other comprehensive income		0
OTTI Losses Recognized in Earnings		$ 3

Investments (Components Of Net

Investments (Components Of Net Realized Gains, Excluding OTTI Charges) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
HTM securities realized gain	$ 0	$ 0
HTM fixed income securities losses	(1)	(1)
Other investments gains	480	0
Other investments losses	(14)	(4)
Total net realized gains (excluding OTTI charges)	2,430	889
Proceeds from sale of available for sale securities	600,300	17,200
Fixed Income Securities [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
AFS securities gains	3,552	620
AFS securities losses	(1,587)	(36)
Equity Securities [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
AFS securities gains	0	330
AFS securities losses	$ 0	$ (20)

Indebtedness Indebtedness (Deta

Indebtedness Indebtedness (Details) - Zero Point Seventy Five Percent Borrowing From Federal Home Loan Bank Due March 21, 2017 [Member] $ in Millions	Mar. 31, 2017USD ($)
Short-term Debt [Line Items]
Federal Home Loan Bank Advances	$ 64
Federal Home Loan Bank, Advances, Interest Rate	0.75%

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Disclosures of Fair Value Assets) (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Debt Securities		$ 4,867,005	$ 4,792,540
Equity securities, AFS		154,918	146,753
Total AFS securities		5,021,923	4,939,293
Short-term investments		247,207	221,701
Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		4,867,005	4,792,540
Equity securities, AFS		154,918	146,753
Total AFS securities		5,021,923	4,939,293
Short-term investments		247,207	221,701
Total assets measured at fair value		5,269,130	5,160,994
U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		88,338	77,333
Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		32,593	26,865
Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		1,287,166	1,379,593
Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		1,828,126	1,997,753
Collateralized Loan Obligations and Other Asset Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		678,435	528,960
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		263,756	256,842
Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities		688,591	525,194
Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS		138,331	130,608
Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS		16,587	16,145
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	46,150	27,520
Equity securities, AFS	[1]	147,242	139,077
Total AFS securities	[1]	193,392	166,597
Short-term investments	[1]	247,207	221,701
Total assets measured at fair value	[1]	440,599	388,298
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]	46,150	27,520
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] | Collateralized Loan Obligations and Other 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]	130,655	122,932
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member]
Equity securities, AFS	[1]	16,587	16,145
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	4,820,855	4,765,020
Equity securities, AFS	[1]	0	0
Total AFS securities	[1]	4,820,855	4,765,020
Short-term investments	[1]	0	0
Total assets measured at fair value	[1]	4,820,855	4,765,020
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]	42,188	49,813
Significant Other Observable Inputs (Level 2) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	32,593	26,865
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]	1,287,166	1,379,593
Significant Other Observable Inputs (Level 2) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	1,828,126	1,997,753
Significant Other Observable Inputs (Level 2) [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	678,435	528,960
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	263,756	256,842
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	[1]	688,591	525,194
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	7,676
Total AFS securities		7,676	7,676
Short-term investments		0	0
Total assets measured at fair value		7,676	7,676
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] | Collateralized Loan Obligations and Other 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	7,676
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 (Quan46

Fair Value Measurements (Quantitative Information of Our Financial Assets and Liabilities That Were Disclosed at Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	$ 88,339	$ 105,211
Long-term debt	438,782	438,667
Seven Point Twenty Five Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	56,225	56,148
Six Point Seventy Percent Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	108,553	108,333
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	185,666	176,860
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	24,393	24,286
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	24,329	24,219
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	59,620	59,313
Long-term Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	458,786	449,159
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	64,760	79,916
Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value	23,579	24,075
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity Securities, Fair Value		1,220
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
Long-term debt	185,666	176,860
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	185,666	176,860
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, Fair Value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, 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] | 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
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	80,758	97,701
Long-term debt	273,120	272,299
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	56,225	56,148
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	108,553	108,333
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, Fair Value	24,393	24,286
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, Fair Value	24,329	24,219
Significant Other Observable Inputs (Level 2) [Member] | Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	59,620	59,313
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	64,760	79,916
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	15,998	16,565
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		1,220
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	7,581	7,510
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, Fair Value	0	0
Significant Unobservable Inputs (Level 3) [Member] | Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	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	$ 7,581	7,510
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

Reinsurance (List of Direct, As

Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Premiums written:
Direct	$ 683,820	$ 646,278
Assumed	5,691	6,320
Ceded	(90,807)	(87,239)
Net	598,704	565,359
Premiums earned:
Direct	646,728	606,661
Assumed	5,779	6,270
Ceded	(91,653)	(90,473)
Net	560,854	522,458
Loss and loss expense incurred:
Direct	342,122	361,639
Assumed	4,437	6,355
Ceded	(29,087)	(70,850)
Net	317,472	297,144
National Flood Insurance Program [Member]
Premiums written:
Ceded	(56,334)	(53,248)
Premiums earned:
Ceded	(57,277)	(56,814)
Loss and loss expense incurred:
Ceded	$ (6,541)	$ (40,718)

Reinsurance (Ceded Premiums and

Reinsurance (Ceded Premiums and Losses Related to Flood Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Ceded premiums written	$ (90,807)	$ (87,239)
Ceded premiums earned	(91,653)	(90,473)
Ceded loss and loss expense incurred	(29,087)	(70,850)
National Flood Insurance Program [Member]
Ceded premiums written	(56,334)	(53,248)
Ceded premiums earned	(57,277)	(56,814)
Ceded loss and loss expense incurred	$ (6,541)	$ (40,718)
Percentage of NFIP claims ceded by federal government	100.00%

Reserve for Losses and Loss E49

Reserve for Losses and Loss Expenses Reserves for Losses and Loss Expenses (Rollforward of Reserves for Losses and Loss Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Liability for Catastrophe Claims [Line Items]
Gross reserves for losses and loss expenses, at beginning of year	$ 3,691,719	$ 3,517,728
Less: reinsurance recoverable on unpaid losses and loss expenses, at beginning of year	611,200	551,019
Net reserves for losses and loss expenses, at beginning of year	3,080,519	2,966,709
Incurred losses and loss expenses for claims occurring in the current year	331,331	312,778
Prior Year Claims and Claims Adjustment Expense	(13,859)	(15,634)
Total incurred losses and loss expenses	317,472	297,144
Paid losses and loss expenses for claims occurring in the current year	54,708	44,310
Paid losses and loss expenses for claims occurring in the prior years	235,742	212,368
Total paid losses and loss expenses	290,450	256,678
Net reserves for losses and loss expenses, at end of period	3,107,541	3,007,175
Add: reinsurance recoverable on unpaid losses and loss expenses, at end of period	571,930	568,321
Gross reserves for losses and loss expenses, at end of period	3,679,471	3,575,496
Change in Historical Claim Rate Experience [Member]
Liability for Catastrophe Claims [Line Items]
Prior Year Claims and Claims Adjustment Expense	13,900	15,600
Change in Historical Claim Rate Experience [Member] | General Liability [Member]
Liability for Catastrophe Claims [Line Items]
Prior Year Claims and Claims Adjustment Expense	22,400	11,000
Change in Historical Claim Rate Experience [Member] | Commercial Automobile [Member]
Liability for Catastrophe Claims [Line Items]
Prior Year Claims and Claims Adjustment Expense	6,000	5,000
Change in Historical Claim Rate Experience [Member] | Personal Automobile [Member]
Liability for Catastrophe Claims [Line Items]
Prior Year Claims and Claims Adjustment Expense	$ 2,000
Change in Historical Claim Rate Experience [Member] | Workers Compensation [Member]
Liability for Catastrophe Claims [Line Items]
Prior Year Claims and Claims Adjustment Expense		12,000
Change in Historical Claim Rate Experience [Member] | Excess And Surplus Operations [Member]
Liability for Catastrophe Claims [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 1,000

Segment Information Narrative (

Segment Information Narrative (Details)	3 Months Ended
	Mar. 31, 2017
Number of Operating Segments	4

Segment Information (Revenue by

Segment Information (Revenue by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total net premiums earned	$ 560,854	$ 522,458
Net investment income	37,419	30,769
Net realized investment losses	(1,045)	(2,704)
Total investment revenues	36,374	28,065
Other income	3,241	951
Total revenues	600,469	551,474
Standard Commercial Lines [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	441,274	403,579
Standard Commercial Lines [Member] | Commercial Automobile [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	107,129	95,419
Standard Commercial Lines [Member] | Workers Compensation [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	79,326	76,000
Standard Commercial Lines [Member] | General Liability [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	139,984	128,085
Standard Commercial Lines [Member] | Commercial Property [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	76,391	70,178
Standard Commercial Lines [Member] | Business Owners' Policies [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	24,845	23,904
Standard Commercial Lines [Member] | Bonds Segment [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	6,498	5,464
Standard Commercial Lines [Member] | Other Commercial [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	4,241	3,839
Standard Commercial Lines [Member] | Miscellaneous Income [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	2,860	690
Standard Personal Lines [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	71,582	70,465
Standard Personal Lines [Member] | Miscellaneous Income [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	381	260
Standard Personal Lines [Member] | Personal Automobile [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	36,950	35,780
Standard Personal Lines [Member] | Homeowners [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	32,700	32,900
Standard Personal Lines [Member] | Other Personal [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	1,551	1,525
Excess And Surplus Operations [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	51,239	49,365
Excess And Surplus Operations [Member] | General Liability [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	37,912	36,856
Excess And Surplus Operations [Member] | Commercial Property [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	13,327	12,508
Excess And Surplus Operations [Member] | Miscellaneous Income [Member]
Segment Reporting Information [Line Items]
Total net premiums earned	$ 0	$ 1

Segment Information (Income Bef

Segment Information (Income Before Federal Income Tax) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Net investment income	$ 37,419	$ 30,769
Net realized investment losses	(1,045)	(2,704)
Total investment income, before federal income tax	36,374	28,065
Tax on investment income	9,602	6,263
Total investment income, after federal income tax	26,772	21,802
Standard Commercial Lines [Member]
Segment Reporting Information [Line Items]
Underwriting gain, before federal income tax	$ 42,546	$ 30,932
GAAP combined ratio	90.30%	92.30%
Statutory combined ratio	88.30%	89.70%
Standard Personal Lines [Member]
Segment Reporting Information [Line Items]
Underwriting gain, before federal income tax	$ 5,106	$ 8,605
GAAP combined ratio	92.80%	87.70%
Statutory combined ratio	93.90%	90.60%
Excess And Surplus Operations [Member]
Segment Reporting Information [Line Items]
Underwriting gain, before federal income tax	$ 1,570	$ 1,418
GAAP combined ratio	96.90%	97.10%
Statutory combined ratio	95.90%	98.40%

Segment Information (Reconcilia

Segment Information (Reconciliation of Segment Results to Income Before Federal Income Tax (Details)) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Investment income, before federal income tax	$ 36,374	$ 28,065
Interest expense	(6,106)	(5,606)
General corporate and other expenses	(11,916)	(11,539)
Income before federal income tax	67,574	51,875
Standard Commercial Lines [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting gain, before federal income tax	42,546	30,932
Standard Personal Lines [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting gain, before federal income tax	5,106	8,605
Excess And Surplus Operations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting gain, before federal income tax	1,570	1,418
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total all segments	$ 85,596	$ 69,020

Retirement Plans (Components of

Retirement Plans (Components of Net Periodic Benefit Cost) (Details) - Pension Plan [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 0	$ 1,606
Interest cost	3,111	3,102
Expected return on plan assets	(4,854)	(3,988)
Amortization of unrecognized net actuarial loss	481	1,480
Total net periodic cost	$ (1,262)	$ 2,200

Retirement Plans (Weighted-Aver

Retirement Plans (Weighted-Average Expense Assumptions) (Details) - Pension Plan [Member]	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.41%	4.69%
Effective interest rate for calculation of service cost		4.52%
Effective interest rate for calculation of interest cost	3.83%	4.02%
Expected return on plan assets	6.24%	6.37%
Rate of compensation increase		4.00%

Comprehensive Income (Component

Comprehensive Income (Components of Comprehensive Income-Gross and Net of Tax) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income, Gross	$ 67,574	$ 51,875
Unrealized holding gains during the period, Gross	25,785	65,737
Amounts reclassified into net income: HTM securities, Gross	(49)	(72)
Amounts reclassified into net income: Realized losses on AFS securities, Gross	1,510	2,699
Total unrealized gains on investment securities, Gross	27,246	68,364
Amount reclassified into net income: Net actuarial loss, Gross	507	1,516
Total defined pension and other post-retirement benefit plans, Gross	507	1,516
Other comprehensive income, Gross	27,753	69,880
Comprehensive income before tax	95,327	121,755
Net income, Tax	17,134	14,843
Unrealized holding gains during the period, Tax	9,024	23,008
Amounts reclassified into net income: HTM securities, Tax	(17)	(25)
Amounts reclassified into net income: Realized losses on AFS securities, Tax	529	945
Total unrealized gains on investment securities, Tax	9,536	23,928
Amount reclassified into net income: Net actuarial loss, Tax	177	530
Total defined pension and other post-retirement benefit plans, Tax	177	530
Other comprehensive income, Tax	9,713	24,458
Comprehensive income, Tax	26,847	39,301
Net income	50,440	37,032
Unrealized holding gains arising during period	16,761	42,729
Amounts reclassified into net income: HTM Securities	(32)	(47)
Amounts reclassified into net income: Realized losses on available-for-sale securities	981	1,754
Total unrealized gains on investment securities	17,710	44,436
Amount reclassified into net income: Net actuarial loss	330	986
Total defined benefit pension and post-retirement plans	330	986
Other comprehensive income	18,040	45,422
Comprehensive income	$ 68,480	$ 82,454

Comprehensive Income (Compone57

Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016	$ (15,950)
Amounts reclassified into net income: Non-credit OTTI	0
OCI before reclassifications, Defined Benefit Pension and Post Retirement Plans	0
Amount reclassified into net income: Net actuarial loss	330	$ 986
Amounts reclassified from AOCI, HTM related	(32)	(47)
Amounts reclassified from AOCI, All Other	981	1,754
Other comprehensive income	18,040	45,422
Other Comprehensive Income, Defined Benefit Pension and Post Retirement Plans, Adjustment, Net of Tax	330	986
Ending Balance, March 31, 2017	2,090
Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016	42,170
OCI before reclassifications	16,761
Other comprehensive income	17,742
Ending Balance, March 31, 2017	59,912
Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016	42,122
OCI before reclassifications	16,761
Amounts reclassified from AOCI	949
Other comprehensive income	17,710
Ending Balance, March 31, 2017	59,832
Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016	(150)
OCI before reclassifications	0
Other comprehensive income	0
Ending Balance, March 31, 2017	(150)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Held-to-maturity Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016	102
OCI before reclassifications	0
Other comprehensive income	(32)
Ending Balance, March 31, 2017	70
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016	(58,072)
Amount reclassified into net income: Net actuarial loss	330
Ending Balance, March 31, 2017	(57,742)
Accumulated other comprehensive income (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016	(15,950)
OCI before reclassifications	16,761
Amounts reclassified from AOCI	1,279
Other comprehensive income	18,040	$ 45,422
Ending Balance, March 31, 2017	$ 2,090

Comprehensive Income (Reclassif

Comprehensive Income (Reclassification out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Total net realized losses	$ (1,045)	$ (2,704)
Net investment income	37,419	30,769
Losses and loss expenses incurred	317,472	297,144
Policy acquisition costs	196,228	183,227
Income before federal income tax	67,574	51,875
Total federal income tax expense	(17,134)	(14,843)
Net income	50,440	37,032
Reclassification out of AOCI
Net income	1,279	2,693
Pension Plan [Member] | Reclassification out of AOCI
Losses and loss expenses incurred	110	329
Policy acquisition costs	397	1,187
Income before federal income tax	507	1,516
Total federal income tax expense	(177)	(530)
Net income	330	986
Held-to-maturity Securities [Member] | Reclassification out of AOCI
Total net realized losses	13	28
Net investment income	(62)	(100)
Income before federal income tax	(49)	(72)
Total federal income tax expense	17	25
Net income	(32)	(47)
Available-for-sale Securities [Member] | Reclassification out of AOCI
Total net realized losses	1,510	2,699
Income before federal income tax	1,510	2,699
Total federal income tax expense	(529)	(945)
Net income	$ 981	$ 1,754

Related Party Transactions Re59

Related Party Transactions Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Assets under Management, Carrying Amount			$ 5,400,000
Percentage Common Stock Owned by Related Party	12.70%
Expenses Incurred, Related Parties	$ 0.5	$ 0
Due to Related Parties	$ 0.8		$ 0.4