Employers (EIG) 10-K 24 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 16, 2017	Jun. 30, 2016
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Entity Registrant Name	Employers Holdings, Inc.
Entity Central Index Key	1,379,041
Current Fiscal Year End Date	--12-31
Entity Well Know Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock Shares Outstanding		32,145,592
Entity Public Float			$ 917,071,061
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investments:
Fixed maturity securities at fair value (amortized cost $2,305.9 at December 31, 2016 and $2,221.1 at December 31, 2015)	$ 2,344,400	$ 2,288,500
Equity securities at fair value (cost $116.1 at December 31, 2016 and $137.5 at December 31, 2015)	192,200	198,700
Short-term investments at fair value (amortized cost $16.0 at December 31, 2016)	16,000	0
Total investments	2,552,600	2,487,200
Cash and cash equivalents	67,200	56,600
Restricted cash and cash equivalents	3,600	2,500
Accrued investment income	20,600	20,600
Premiums receivable (less bad debt allowance of $9.8 at December 31, 2016 and $12.2 at December 31, 2015)	304,700	301,100
Reinsurance recoverable for:
Paid losses	8,700	7,700
Unpaid losses	580,000	628,200
Deferred policy acquisition costs	44,300	44,300
Deferred income taxes, net	59,400	67,900
Property and equipment, net	22,200	24,900
Intangible assets, net	8,200	8,500
Goodwill	36,200	36,200
Contingent commission receivable–LPT Agreement	31,100	29,200
Other assets	34,600	40,900
Total assets	3,773,400	3,755,800
Claims and policy liabilities:
Unpaid losses and loss adjustment expenses	2,301,000	2,347,500
Unearned premiums	310,300	308,900
Total claims and policy liabilities	2,611,300	2,656,400
Commissions and premium taxes payable	48,800	52,500
Accounts payable and accrued expenses	24,200	24,100
Deferred reinsurance gain—LPT Agreement	174,900	189,500
Notes payable	32,000	32,000
Other liabilities	41,600	40,500
Total liabilities	2,932,800	2,995,000
Commitments and contingencies (Note 12)
Stockholders’ equity:
Common stock, $0.01 par value; 150,000,000 shares authorized; 56,226,277 and 55,589,454 shares issued and 32,128,922 and 32,216,480 shares outstanding at December 31, 2016 and 2015, respectively	600	600
Preferred stock, $0.01 par value; 25,000,000 shares authorized; none issued	0	0
Additional paid-in capital	372,000	357,200
Retained earnings	777,200	682,000
Accumulated other comprehensive income, net of tax	74,500	83,600
Treasury stock, at cost (24,097,355 shares at December 31, 2016 and 23,372,974 shares at December 31, 2015)	(383,700)	(362,600)
Total stockholders’ equity	840,600	760,800
Total liabilities and stockholders’ equity	$ 3,773,400	$ 3,755,800

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investments:
Amortized cost	$ 2,438,000	$ 2,358,600
Premiums receivable, bad debt allowance	$ 9,800	$ 12,200
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	56,226,277	55,589,454
Common stock, shares outstanding (in shares)	32,128,922	32,216,480
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Treasury stock, at cost (in shares)	24,097,355	23,372,974
Debt Securities [Member]
Investments:
Amortized cost	$ 2,305,900	$ 2,221,100
Equity Securities [Member]
Investments:
Amortized cost	116,100	137,500
Short-term Investments [Member]
Investments:
Amortized cost	$ 16,000	$ 0

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Net premiums earned	$ 694,800	$ 690,400	$ 684,500
Net investment income	73,200	72,200	72,400
Net realized gains (losses) on investments	11,200	(10,700)	16,300
Other income	600	200	300
Total revenues	779,800	752,100	773,500
Expenses
Losses and loss adjustment expenses	417,900	429,400	453,400
Commission expense	83,500	85,400	81,400
Underwriting and other operating expenses	136,100	135,200	129,100
Interest expense	1,600	2,700	3,000
Total expenses	639,100	652,700	666,900
Net income before income taxes	140,700	99,400	106,600
Income tax expense	34,000	5,000	5,900
Net income	106,700	94,400	100,700
Comprehensive income
Unrealized (losses) gains during the period (net of taxes of $(1.0), $(16.3), and $14.6 for the years ended December 31, 2016, 2015, and 2014, respectively)	(1,800)	(30,300)	27,100
Reclassification adjustment for realized (gains) losses in net income (net of taxes of $3.9, $(3.7), and $5.7 for the years ended December 31, 2016, 2015, and 2014, respectively)	(7,300)	7,000	(10,600)
Other comprehensive (loss) income, net of tax	(9,100)	(23,300)	16,500
Total comprehensive income	$ 97,600	$ 71,100	$ 117,200
Earnings per common share (Note 18):
Basic	$ 3.29	$ 2.94	$ 3.19
Diluted	3.24	2.90	3.14
Cash dividends declared per common share	$ 0.36	$ 0.24	$ 0.24
Net realized gains (losses) on investments
Net realized gains on investments before impairments on fixed maturity and equity securities	$ 17,000	$ 6,500	$ 16,800
Other than temporary impairments recognized in earnings	(5,800)	(17,200)	(500)
Net realized gains (losses) on investments	$ 11,200	$ (10,700)	$ 16,300

Consolidated Statements of Com5

Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Comprehensive Income Parenthetical [Abstract]
Other comprehensive income (loss), unrealized holding gain (loss) on securities arising during period, tax	$ (1,000)	$ (16,300)	$ 14,600
Other comprehensive income (loss), reclassification adjustment for sale of securities included in net income, tax	$ 3,900	$ (3,700)	$ 5,700

Consolidated Statements of Stoc

Consolidated Statements of Stockholders Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income, Net	Treasury Stock at Cost
Stockholders' equity, shares at Dec. 31, 2013		54,672,904
Stockholders' equity, value at Dec. 31, 2013	$ 568,700	$ 600	$ 338,100	$ 502,200	$ 90,400	$ (362,600)
Stock-based compensation (Note 14), shares		0
Stock-based compensation (Note 14), value	6,000	$ 0	6,000	0	0	0
Stock-options exercised, shares		120,494
Stock options exercised, value	2,200	$ 0	2,200	0	0	0
Vesting of restricted stock units, net of shares withheld to satisfy minimum tax withholding (Note 14), shares		73,404
Vesting of restricted stock units, net of shares withheld to satisfy minimum tax withholding (Note 14), value	(600)	$ 0	(600)	0	0	0
Acquisition of treasury stock (Note 13), shares		0
Acquisition of treasury stock (Note 13), value	(21,100)	$ 0	0	0	0	(21,100)
Dividend to common stockholders, shares		0
Dividend to common stockholders, value	7,600	$ 0	0	7,600	0	0
Stockholders' equity, shares at Dec. 31, 2014		54,866,802
Excess tax benefit from stock-based compensation	900	$ 0	900	0	0	0
Net income for the period	100,700	0	0	100,700	0	0
Change in net unrealized gains on investments, net of taxes	16,500	0	0	0	16,500	0
Stockholders' equity, value at Dec. 31, 2014	686,800	$ 600	346,600	595,300	106,900	(362,600)
Stock-based compensation (Note 14), shares		0
Stock-based compensation (Note 14), value	4,600	$ 0	4,600	0	0	0
Stock-options exercised, shares		463,466
Stock options exercised, value	7,600	$ 0	7,600	0	0	0
Vesting of restricted stock units, net of shares withheld to satisfy minimum tax withholding (Note 14), shares		259,186
Vesting of restricted stock units, net of shares withheld to satisfy minimum tax withholding (Note 14), value	(2,700)	$ 0	(2,700)	0	0	0
Dividend to common stockholders, shares		0
Dividend to common stockholders, value	$ 7,700	$ 0	0	7,700	0	0
Stockholders' equity, shares at Dec. 31, 2015	55,589,454	55,589,454
Excess tax benefit from stock-based compensation	$ 1,100	$ 0	1,100	0	0	0
Net income for the period	94,400	0	0	94,400	0	0
Change in net unrealized gains on investments, net of taxes	(23,300)	0	0	0	(23,300)	0
Stockholders' equity, value at Dec. 31, 2015	760,800	$ 600	357,200	682,000	83,600	(362,600)
Stock-based compensation (Note 14), shares		0
Stock-based compensation (Note 14), value	5,800	$ 0	5,800	0	0	0
Stock-options exercised, shares		586,132
Stock options exercised, value	9,600	$ 0	9,600	0	0	0
Vesting of restricted stock units, net of shares withheld to satisfy minimum tax withholding (Note 14), shares		50,691
Vesting of restricted stock units, net of shares withheld to satisfy minimum tax withholding (Note 14), value	(600)	$ 0	(600)	0	0	0
Dividend to common stockholders, shares		0
Dividend to common stockholders, value	$ 11,500	$ 0	0	11,500	0	0
Stockholders' equity, shares at Dec. 31, 2016	56,226,277	56,226,277
Net income for the period	$ 106,700	$ 0	0	106,700	0	0
Change in net unrealized gains on investments, net of taxes	(9,100)	0	0	0	(9,100)	0
Stockholders' equity, value at Dec. 31, 2016	$ 840,600	$ 600	$ 372,000	$ 777,200	$ 74,500	$ (383,700)

Consolidated Stockholders Equit

Consolidated Stockholders Equity (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stockholders Equity Parenthetical [Abstract]
Change in net unrealized gains on investments, net of tax of	$ (4,900)	$ (12,600)	$ 8,900

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income	$ 106,700	$ 94,400	$ 100,700
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,500	8,300	7,000
Stock-based compensation	5,800	4,600	6,000
Amortization of premium on investments, net	14,600	12,800	10,600
Allowance for doubtful accounts	(2,400)	4,300	800
Deferred income tax expense (benefit)	13,400	(5,600)	(500)
Net realized (gains) losses on investments	(11,200)	10,700	(16,300)
Excess tax benefits from stock-based compensation	0	(1,200)	(1,200)
Other operating activities, adjustments to reconcile net income to net cash	0	100	(300)
Change in operating assets and liabilities:
Premiums receivable	(1,200)	(9,600)	(17,600)
Reinsurance recoverable on paid and unpaid losses	47,200	44,300	71,300
Federal income taxes	7,700	(3,900)	6,500
Unpaid losses and loss adjustment expenses	(46,500)	(22,200)	39,200
Unearned premiums	1,400	(1,900)	6,800
Accounts payable, accrued expenses and other liabilities	(4,200)	8,600	12,800
Deferred reinsurance gain–LPT Agreement	(14,600)	(17,500)	(42,100)
Contingent commission receivable–LPT Agreement	(1,900)	(2,800)	(1,300)
Other	(500)	(7,000)	(10,500)
Net cash provided by operating activities	122,800	116,400	171,900
Investing activities
Purchases of fixed maturity securities	(466,800)	(476,900)	(378,000)
Purchases of equity securities	(49,100)	(85,100)	(29,500)
Purchase of short-term investments	(10,000)	0	0
Proceeds from sale of fixed maturity securities	132,400	105,400	47,900
Proceeds from sale of equity securities	80,400	34,700	36,500
Proceeds from maturities and redemptions of investments	230,600	323,900	251,100
Capital expenditures and other	(5,000)	(11,500)	(10,500)
Change in restricted cash and cash equivalents	(1,100)	8,300	(4,200)
Net cash used in investing activities	(88,600)	(101,200)	(86,700)
Financing activities
Acquisition of common stock	(21,100)	0	0
Cash transactions related to stock-based compensation	9,000	4,800	1,600
Dividends paid to stockholders	(11,500)	(7,700)	(7,600)
Payments on notes payable and capital leases	0	(60,500)	(11,300)
Excess tax benefits from stock-based compensation	0	1,200	1,200
Net cash used in financing activities	(23,600)	(62,200)	(16,100)
Net increase (decrease) in cash and cash equivalents	10,600	(47,000)	69,100
Cash and cash equivalents at the beginning of the period	56,600	103,600	34,500
Cash and cash equivalents at the end of the period	67,200	56,600	103,600
Non-cash transactions
Financed property and equipment purchases	700	300	700
Non-cash exchange of fixed maturity investments for short-term investments	$ 6,000	$ 0	$ 0

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2016
Basis of Presentation [Abstract]
Basis of Presentation	Basis of Presentation and Summary of Operations Nature of Operations and Organization Employers Holdings, Inc. (EHI) is a Nevada holding company. Through its wholly owned insurance subsidiaries, Employers Insurance Company of Nevada (EICN), Employers Compensation Insurance Company (ECIC), Employers Preferred Insurance Company (EPIC), and Employers Assurance Company (EAC), EHI is engaged in the commercial property and casualty insurance industry, specializing in workers' compensation products and services. Unless otherwise indicated, all references to the “Company” refer to EHI, together with its subsidiaries. In 1999, the Nevada State Industrial Insurance System (the Fund) entered into a retroactive 100% quota share reinsurance agreement (the LPT Agreement) through a loss portfolio transfer transaction with third party reinsurers. The LPT Agreement commenced on June 30, 1999 and will remain in effect until all claims under the covered policies have closed, the LPT Agreement is commuted or terminated, upon the mutual agreement of the parties, or the reinsurers' aggregate maximum limit of liability is exhausted, whichever occurs first. The LPT Agreement does not provide for any additional termination terms. On January 1, 2000, EICN assumed all of the assets, liabilities and operations of the Fund, including the Fund's rights and obligations associated with the LPT Agreement. See Notes 3 and 10 . The Company accounts for the LPT Agreement as retroactive reinsurance. Upon entry into the LPT Agreement, an initial deferred reinsurance gain (the Deferred Gain) was recorded as a liability on the Company’s Consolidated Balance Sheets. The Company is entitled to receive a contingent profit commission under the LPT Agreement. The contingent profit commission is estimated based on both actual paid results to date and projections of expected paid losses under the LPT Agreement and is recorded as an asset on the Company's Consolidated Balance Sheets. Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP). All intercompany transactions and balances have been eliminated in consolidation. The Company operates as a single operating segment, workers’ compensation insurance, through its wholly owned subsidiaries. The Company considers an operating segment to be any component of its business whose operating results are regularly reviewed by the Company's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance based on discrete financial information. Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. As a result, actual results could differ from these estimates. The most significant areas that require management judgment are the estimate of unpaid losses and loss adjustment expenses (LAE), evaluation of reinsurance recoverables, recognition of premium revenue, recoverability of deferred income taxes, and valuation of investments.

Changes in Estimates Level 1 (N

Changes in Estimates Level 1 (Notes)	12 Months Ended
	Dec. 31, 2016
Changes in Estimates [Abstract]
Accounting Changes and Error Corrections	Changes in Estimates The Company reduced its estimated loss and LAE reserves ceded under the LPT Agreement (LPT Reserve Adjustments) in each of the years 2016 , 2015 , and 2014 as a result of the determination that adjustments were necessary to reflect observed favorable paid loss trends in each of these years. The following table shows the financial statement impact related to the LPT Reserve Adjustments. 2016 2015 2014 (in millions, except per share data) LPT Reserve Adjustments $ (5.0 ) $ (10.0 ) $ (46.8 ) Cumulative adjustment to the Deferred Gain (1) (3.1 ) (6.4 ) (31.1 ) Net income impact from this change in estimate 3.1 6.4 31.1 Earnings per common share impact from this change in estimate Basic 0.10 0.20 0.99 Diluted 0.09 0.20 0.97 (1) The cumulative adjustments to the Deferred Gain were also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised loss and LAE reserves been recognized at the inception of the LPT Agreement. The Company increased its estimate of Contingent commission receivable – LPT Agreement (LPT Contingent Commission Adjustments) in each of 2016 , 2015 , and 2014 as a result of the determination that adjustments were necessary to reflect observed favorable paid loss trends in each of those years. The following table shows the impact to the Consolidated Statements of Comprehensive Income related to these changes in estimates. 2016 2015 2014 (in millions, except per share data) Change in estimate of Contingent commission receivable - LPT Agreement $ 1.9 $ 2.8 $ 12.5 Cumulative adjustment to the Deferred Gain (1) (1.8 ) (2.6 ) (10.8 ) Net income impact from this change in estimate 1.8 2.6 10.8 Earnings per common share impact from this change in estimate Basic 0.06 0.08 0.34 Diluted 0.05 0.08 0.34 (1) The cumulative adjustments to the Deferred Gain were also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised loss and LAE reserves been recognized at the inception of the LPT Agreement. The Company reallocated loss and LAE reserves from non-taxable periods prior to January 1, 2000 to taxable years, which reduced its effective tax rates, in each of 2015 and 2014 . These changes in estimates were the result of the determination that a reallocation of reserves among accident years was appropriate to address a continuation of observed loss trends in each of those years. The following table shows the financial statement impact of these changes in estimates. 2015 2014 (in millions, except per share data) Loss and LAE reserves reallocated to taxable years $ 56.3 $ 13.1 Impact to effective tax rate (15.4 )% (3.4 )% Net income impact from this change in estimate $ 15.3 $ 3.6 Earnings per common share impact from this change in estimate Basic 0.48 0.11 Diluted 0.47 0.11 No reallocations of losses and LAE reserves from non-taxable periods were made in 2016 .

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies [Abstract]
Significant Accounting Policies	Summary of Significant Accounting Policies Cash and Cash Equivalents The Company considers all liquid investments with maturities of less than three months, as measured from the date of purchase, to be cash equivalents. Restricted Cash and Cash Equivalents Restricted cash and cash equivalents represent cash and cash equivalents held in trust in order to secure certain of the Company's obligations and, accordingly, are restricted as to withdrawal or usage. As of December 31, 2016 and 2015 the Company held $27.2 million and $32.7 million , respectively, in trust for reinsurance obligations, of which $3.6 million and $2.5 million , respectively, represented restricted cash and cash equivalents. Short-Term Investments The Company considers all liquid investments with maturities of between three and twelve months, as measured from the date of purchase, to be short-term investments. Investment Securities The Company's investments in fixed maturity securities and equity securities are classified as available-for-sale and are reported at fair value with unrealized gains and losses excluded from earnings and reported as a separate component of stockholders' equity, net of deferred taxes, in accumulated other comprehensive income on the Company’s Consolidated Balance Sheets. Investment income consists primarily of interest and dividends generated by investment securities. Interest is recorded as earned on an accrual basis and dividends are recorded as earned at the ex-dividend date. Interest income on mortgage-backed and asset-backed securities is determined using the effective-yield method based on estimated principal repayments. Mortgage-backed securities are adjusted for the effects of changes in prepayment assumptions on the related accretion of discount or amortization of premium of such securities using the retrospective method. Realized gains and losses on investments are determined on a specific-identification basis. When, in the opinion of management, a decline in the fair value of an equity security below its cost is considered to be “other-than-temporary,” the equity security's cost is written down to its fair value at the time the other-than-temporary decline is identified. The determination of an other-than-temporary decline for fixed maturity securities includes, in addition to other relevant factors, a presumption that if the market value is below cost by a significant amount for a period of time, a bifurcation of the write-down may be necessary based on the portion of the loss that is deemed to be a “credit loss”, which is considered a realized loss, and the portion that is deemed to be an “other than credit loss”, which is considered to be an unrealized loss. If management has the intent to sell the fixed maturity security or more likely than not will be required to sell the fixed maturity security before its anticipated recovery, the investment is written down to its fair value and the entire impairment is recorded as a realized loss in the Company's Consolidated Statements of Comprehensive Income. If management does not have the intent to sell or will not be required to sell the fixed maturity security but does not expect to recover the amortized cost basis of the fixed maturity security, the amount of the other-than-temporary impairment is bifurcated (see Note 6 ). Recognition of Revenue and Expense Revenue Recognition Premiums written are recognized as revenues, net of any applicable underlying reinsurance coverage, and are earned over the term of the related policy. At the end of the policy term, payroll-based premium audits are performed on substantially all policyholder accounts to determine the actual amount of net premiums earned for that policy year. Earned but unbilled premiums include estimated future audit premiums based on the Company's historical experience. These estimates are subject to changes in policyholders' payrolls, economic conditions, and seasonality, and are continually reviewed and adjusted as experience develops or new information becomes known. Any such adjustments are included in current operations; however, they are partially offset by the resulting changes in losses and LAE, commission expenses, and premium taxes. The Company's premiums receivable on its Consolidated Balance Sheets included $58.4 million and $53.5 million of additional premiums expected to be received from policyholders for final audits at December 31, 2016 and 2015 , respectively. The Company establishes a bad debt allowance on its premiums receivable through a charge included in underwriting and other operating expenses in its Consolidated Statements of Comprehensive Income. This bad debt allowance is determined based on estimates and assumptions to project future experience. After all collection efforts have been exhausted, the Company reduces the bad debt allowance for write-offs of premiums receivable that have been deemed uncollectible. The Company's bad debt allowance was $9.8 million and $12.2 million at December 31, 2016 and 2015 , respectively. The Company had write offs, net of recoveries of amounts previously written off, of $6.0 million , $2.4 million , and $3.4 million for the years ended December 31, 2016 , 2015 , and 2014 , respectively. Deferred Policy Acquisition Costs Policy acquisition costs, those costs that relate directly to the successful acquisition of new or renewal insurance contracts, including underwriting, policy issuance and processing, medical and inspection, and sales force contract selling are deferred and amortized as the related premiums are earned. Amortization of deferred policy acquisition costs for the years ended December 31, 2016 , 2015 , and 2014 , was $104.5 million , $103.9 million , and $102.7 million , respectively. If the sum of a policy’s expected losses and LAE and deferred policy acquisition costs exceeds the related unearned premiums and projected investment income, a premium deficiency is determined to exist. In this event, deferred policy acquisition costs are immediately expensed to the extent necessary to eliminate the premium deficiency. If the premium deficiency exceeds deferred acquisition costs then a liability is accrued for the excess deficiency. There were no premium deficiency adjustments recognized during the years ended December 31, 2016 , 2015 and 2014 . Unpaid Loss and LAE Reserves Unpaid loss and LAE reserves represent management's best estimate of the ultimate net cost of all reported and unreported losses incurred for the applicable periods, less payments made. The estimated reserves for losses and LAE include the accumulation of estimates for all claims reported prior to the balance sheet date, estimates of claims incurred but not reported, and estimates of expenses for investigating and adjusting all incurred and unadjusted claims (based on projections of relevant historical data). Amounts reported are subject to the impact of future changes in economic, regulatory and social conditions. Management believes that, subject to the inherent variability in any such estimate, the reserves are within a reasonable and acceptable range of adequacy. Estimates for claims prior to the balance sheet date are continually monitored and reviewed, and as settlements are made or reserves adjusted, the differences are reported in current operations. Salvage and subrogation recoveries are estimated based on a review of the level of historical salvage and subrogation recoveries. Reinsurance In the ordinary course of business, the Company may purchase excess of loss reinsurance in order to protect it against the impact of large and/or catastrophic losses. Additionally, the Company is a party to the LPT Agreement (see Note 10 ). These reinsurance arrangements reduce the Company's exposure to such losses since its reinsurers are liable to the Company to the extent of the reinsurance protection provided. However, the Company remains liable for all losses it incurs to the extent that any reinsurer is unable or unwilling to make timely payments under its reinsurance agreements. Balances due from reinsurers on unpaid losses, including an estimate of such recoverables related to reserves for incurred but not reported losses, are reported as reinsurance recoverables on the Company’s Consolidated Balance Sheets. Reinsurance recoverables on paid losses represents amounts currently due from reinsurers. Reinsurance recoverables on unpaid losses represents amounts that will be collectible from reinsurers once the losses are paid. Reinsurance recoverables on unpaid losses and LAE amounted to $580.0 million and $628.2 million at December 31, 2016 and 2015 , respectively. Ceded reinsurance premiums are accounted for on a basis consistent with those used in accounting for the underlying premiums, and are reported as reductions to arrive at net premiums written and earned. Ceded losses and LAE are also accounted for on a basis consistent with those used in accounting for the original policies issued and the terms of the relevant reinsurance agreement, and are recorded as reductions to losses and LAE incurred. Pursuant to the LPT Agreement, loss expenses are deemed to be 7% of total losses paid and are payable to the Company as compensation for management of the claims under the LPT Agreement. The Deferred Gain is amortized using the recovery method, whereby the amortization is determined by the proportion of actual reinsurance recoveries to total estimated recoveries through the life of the LPT Agreement, and is recorded in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income. Any adjustment to the estimated loss and LAE reserves ceded under the LPT Agreement results in a cumulative adjustment to the Deferred Gain, which is also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, such that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement. Additionally, the Company is entitled to receive a contingent profit commission under the LPT Agreement. The contingent profit commission is equal to 30% of the favorable difference between actual paid losses and LAE and expected paid losses and LAE as established in the LPT Agreement based on losses paid through June 30, 2024. The contingent profit commission is paid every five years beginning June 30, 2004 for the first 25 years of the agreement. The Company could be required to return any previously received contingent profit commission, plus interest, in the event of unfavorable differences through June 30, 2024. The Company records an estimate of contingent profit commission in its Consolidated Balance Sheets as Contingent commission receivable–LPT Agreement and a corresponding liability is recorded as Deferred reinsurance gain–LPT Agreement. The Contingent commission receivable–LPT Agreement is reduced as amounts are received from participating reinsurers. The Deferred reinsurance gain–LPT Agreement is amortized using the recovery method. The amortization of the contingent profit commission is determined by the proportion of actual reinsurance recoveries to total estimated recoveries over the life of the contingent profit commission (through June 30, 2024), and is recorded in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income. Any adjustment to the contingent profit commission under the LPT Agreement results in a cumulative adjustment to the Deferred Gain, which is also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, such that the Deferred Gain reflects the balance that would have existed had the revised contingent profit commission been recognized at the inception of the LPT Agreement. Property and Equipment Property and equipment are stated at cost less accumulated depreciation (see Note 7 ). Expenditures for maintenance and repairs are charged against operations as incurred. Electronic data processing equipment, software, furniture and equipment, and automobiles are depreciated using the straight-line method over three to seven years . Leasehold improvements are carried at cost less accumulated amortization. The Company amortizes leasehold improvements using the straight-line method over the lesser of the useful life of the asset or the remaining original lease term, excluding options or renewal periods. Leasehold improvements are generally amortized over three to five years . Obligations Held Under Capital Leases Leased property and equipment meeting capital lease criteria are capitalized at the lower of the present value of the related lease payments or the fair value of the leased asset at the inception of the lease. Amortization is calculated using the straight-line method based on the term of the lease and is included in the depreciation expense of property and equipment. See Note 12 for additional disclosures related to capital leases. Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the Company's financial statements. Under this method, the Company determines deferred tax assets and liabilities on the basis of the differences between the financial statement and tax bases of assets and liabilities by using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company records uncertain tax positions in accordance with ASC 740 on the basis of a two-step process. Recognition (Step 1) occurs when the Company concludes that a tax position, based solely on its technical merits, is more likely than not to be sustained upon examination. Measurement (Step 2) is addressed only if Step 1 has been satisfied. Under Step 2, the tax benefit is measured as the largest amount of benefit, determined on a cumulative probability basis, that is more likely than not to be realized upon ultimate settlement. The Company recognizes deferred tax assets when it determines that such assets are more likely than not to be realized in future periods. In making such a determination, the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If the Company determines that it would be able to realize its deferred tax assets in the future in excess of their net recorded amount, the Company would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents (including restricted cash equivalents), short-term investments, investment securities, premiums receivable, and reinsurance recoverable balances. The Company’s cash equivalents and short-term investments include investments in money market securities and securities backed by the U.S. government. The Company's investment securities are diversified throughout many industries and geographic regions and include investments in U.S. government and U.S. government-sponsored enterprises. The Company believes that it has no significant concentrations of credit risk from a single issue or issuer within its cash equivalents, short-term investments and investment securities other than concentrations in U.S. government and U.S. government-sponsored enterprises. The Company's premiums receivable are generally diversified due to the large number of entities composing the Company's policyholder base and their dispersion across many different industries. The Company monitors the financial condition of its reinsurers to minimize its exposure to significant losses from reinsurer insolvencies. The Company also obtains collateral from its reinsurers in order to mitigate the risks related to insolvencies. At December 31, 2016 , $3.5 million of the Company's reinsurance recoverables were collateralized by cash or letters of credit and an additional $355.7 million was in trust accounts for reinsurance recoverables specifically related to the LPT Agreement. Fair Value of Financial Instruments The fair values of the Company's financial instruments have been determined using available market information and other appropriate valuation methodologies. Judgment is required in developing fair value estimates where quoted market prices are not available. Accordingly, these estimates are not necessarily indicative of the amounts that could be realized in a current market exchange. The use of different market assumptions or estimating methodologies may have an effect on the estimated fair value amounts. The following methods and assumptions were used by the Company in estimating the fair value of its financial instruments: Cash and cash equivalents, short-term investments, premiums receivable, accounts payable, and accrued expenses and other liabilities. The carrying amounts for each of these financial instruments as reported in the Company's Consolidated Balance Sheets approximate their fair values. Investment Securities. The Company’s investment securities are predominantly valued on the basis of actual market transactions or observable inputs. A small portion of the Company’s investment securities are valued on the basis of pricing models with significant unobservable inputs or nonbinding broker quotes. See Note 5 . Goodwill and Other Intangible Assets The Company tests for impairment of goodwill and non-amortizable intangible assets in the fourth quarter of each year. At the end of each quarter, management considers the results of the previous analysis as well as any recent developments that may constitute triggering events requiring the impairment analysis of goodwill and other intangible assets to be updated. The Company has assessed the effects of current economic conditions on the Company's financial condition and results of operations and changes in the Company's stock price and determined that there were no impairments of these assets as of December 31, 2016 and 2015 . Intangible assets related to state licenses are not subject to amortization. Intangibles related to insurance relationships are amortized in proportion to the expected period of benefit over the next two years . The gross carrying value, accumulated amortization, and net carrying value for the Company's intangible assets, by major class, as of December 31, were as follows: 2016 2015 Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value (in millions) State licenses $ 7.7 $ — $ 7.7 $ 7.7 $ — $ 7.7 Insurance relationships 9.4 $ (8.9 ) 0.5 9.4 $ (8.6 ) 0.8 Total $ 17.1 $ (8.9 ) $ 8.2 $ 17.1 $ (8.6 ) $ 8.5 During the years ended December 31, 2016 , 2015 , and 2014 , the Company recognized $0.3 million , $0.5 million , and $0.7 million in amortization expenses associated with its intangible assets, respectively. These amortization expenses are included in the Company's Consolidated Statements of Comprehensive Income in underwriting and other operating expenses. Future amortization expenses associated with the Company's intangible assets are expected to be as follows: Year Amount (in millions) 2017 0.3 2018 0.2 Total $ 0.5 Stock-Based Compensation The Company provides stock-based compensation to its directors and certain of its employees, which is recognized in its Consolidated Statements of Comprehensive Income based on estimated fair values over the relevant service period (see Note 14 ).

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Standards	New Accounting Standards Recently Adopted Accounting Standards In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) Number 2016-09, Compensation - Stock Compensation (Topic 718). This update simplifies several aspects of the accounting for stock-based payment award transactions, including income taxes and classification of awards on the balance sheet and the statement of cash flows. The Company elected to early adopt this standard in the quarter ended September 30, 2016 with an effective date of January 1, 2016. Adoption of this standard had the following impacts on the Company's consolidated financial statements: • Consolidated Statements of Comprehensive Income – This standard requires that the tax effects of stock-based compensation be recognized in income tax expense, as opposed to additional paid-in capital. A net tax benefit related to stock-based compensation of $1.4 million was recognized as a reduction to income tax expense and an increase to net income in the Company's Consolidated Statements of Comprehensive Income for the year ended December 31, 2016. These changes increased basic and diluted earnings per share by $0.04 for the year ended December 31, 2016. This standard also requires that assumed proceeds under the treasury stock method be modified to exclude the excess tax benefits that would have been recognized in Additional paid-in capital. These changes were applied on a prospective basis. • Consolidated Statements of Cash Flows – This standard requires that excess tax benefits from stock-based compensation be reported as cash flows from operating activities, as opposed to financing activities. This update resulted in a change in presentation that was applied on a prospective basis and prior periods have not been adjusted. This standard also allows the Company to make a policy election as to whether it will include an estimate of stock-based compensation awards expected to be forfeited or whether it will account for forfeitures as they occur. The Company has elected to continue to estimate forfeitures in the computation of its stock-based compensation, consistent with previous guidance, and this election had no impact on the Company's consolidated financial statements. Finally, this standard allows the Company to withhold an amount in excess of the statutory supplemental tax rate from an employee’s stock-based compensation for federal tax withholding purposes without triggering liability accounting. It also clarifies that all cash payments made to tax authorities on an employee’s behalf should be presented as cash flows from financing activities in the Company's Consolidated Statements of Cash Flows. This update related to tax withholding and presentation of cash flows had no impact on the Company's consolidated financial statements. Recently Issued Accounting Standards – Not Yet Adopted In January 2016, the FASB issued ASU Number 2016-01, Financial Instruments - Overall (Subtopic 825-10). This update replaces the guidance to classify equity securities with readily determinable fair values into different categories (trading or available-for-sale) and requires equity securities to be measured at fair value with changes in fair value recognized in net income. Additionally, this update eliminates the method and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost. It requires financial instruments to be measured at fair value using the exit price notion. Furthermore, this update clarifies that an evaluation of deferred tax assets related to available-for-sale securities is needed, in combination with an evaluation of other deferred tax assets, to determine if a valuation allowance is required. This update becomes effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. This update will result in a reclassification adjustment, net of tax, to retained earnings from accumulated other comprehensive income, which will be determined based on the fair value of securities at the effective date of adoption. In February 2016, the FASB issued ASU Number 2016-02, Leases (Topic 842). This update provides guidance on a new lessee model that includes the recognition of assets and liabilities arising from lease transactions on the balance sheet. Additionally, the update provides clarity on the definition of a lease and the distinction between finance and operating leases. Furthermore, the update requires certain qualitative and quantitative disclosures pertaining to the amounts recorded in the financial statements. This update becomes effective for annual reporting periods, including interim periods within those annual periods, beginning after December 15, 2018 and early adoption is permitted. The Company has not yet estimated the full impact that the adoption will have on its consolidated financial condition and results of operations. In June 2016, the FASB issued ASU Number 2016-13, Financial Instruments - Credit Losses (Topic 326). This update replaces the incurred loss impairment methodology for recognizing credit losses on financial instruments with a methodology that reflects an entity's current estimate of all expected credit losses. This update requires financial assets measured at amortized cost to be presented net of an allowance for credit losses. Additionally, this update requires credit losses on available-for-sale fixed maturity securities to be presented as an allowance rather than as a write-down, allowing an entity to also record reversals of credit losses in current period net income. This update becomes effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted as of fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company has not yet estimated the full impact that the adoption will have on its consolidated financial condition and results of operations. In August 2016, the FASB issued ASU Number 2016-15, Statement of Cash Flows (Topic 230) . This update provides guidance and clarification on eight specific cash flow issues due to diversity in practice of how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The cash flow issues affected are debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, distributions received from equity method investees, beneficial interest in securitization transactions, and separately identifiable cash flows and application of the predominance principle. This update becomes effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company has determined the adoption of this standard will have no material financial impact on its consolidated financial condition, results of operations, and statement of cash flows. In November 2016, the FASB issued ASU Number 2016-18, Statement of Cash Flows (Topic 230) . This update provides guidance for the classification and presentation of restricted cash and restricted cash equivalents in the statement of cash flows. This update requires amounts generally described as restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. It requires the disclosure of information about the nature of restrictions on its cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. This update also requires the entity to disclose, on the face of the statement of cash flows or in the notes to the financial statements, any restricted cash or restricted cash equivalents disaggregated by the line item in which they appear within the statement of financial position. This update becomes effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company has determined the adoption of this standard will have no material financial impact on its consolidated financial condition, results of operations, and statement of cash flows. In May 2014, the FASB issued ASU Number 2014-09, Revenue from Contracts with Customers (Topic 606). This update clarifies the principles for recognizing revenue and develops revenue standards to improve revenue recognition guidance. This update requires an entity to recognize revenue as performance obligations are met in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. In applying this guidance companies are required to: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract(s); (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract(s); and (5) recognize revenue when, or as, the entity satisfies a performance obligation. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , which deferred the effective date of ASU 2014-09 to annual reporting periods beginning after December 15, 2017, and interim reporting periods within that annual reporting period. Insurance contracts are not within the scope of this updated guidance. The Company has analyzed revenue streams within the current business operation and determined the adoption of this standard will not have an impact on its consolidated financial condition and results of operations.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2016
Fair Value of Financial Instruments [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying value and the estimated fair value of the Company's financial instruments as of December 31, were as follows: 2016 2015 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Financial assets (in millions) Investments (Note 6) $ 2,552.6 $ 2,552.6 $ 2,487.2 $ 2,487.2 Cash and cash equivalents 67.2 67.2 56.6 56.6 Restricted cash and cash equivalents 3.6 3.6 2.5 2.5 Financial liabilities Notes payable (Note 11) $ 32.0 $ 33.0 $ 32.0 $ 36.6 Assets and liabilities recorded at fair value on the Company's Consolidated Balance Sheets are categorized based upon the levels of judgment associated with the inputs used to measure their fair value. Level inputs are defined as follows: • Level 1 - Inputs are unadjusted quoted market prices for identical assets or liabilities in active markets at the measurement date. • Level 2 - Inputs other than Level 1 prices that are observable for similar assets or liabilities through corroboration with market data at the measurement date. • Level 3 - Inputs that are unobservable that reflect management's best estimate of what willing market participants would use in pricing the assets or liabilities at the measurement date. The Company uses third party pricing services to assist with its investment accounting function. The ultimate pricing source varies depending on the investment security and pricing service used, but investment securities valued on the basis of observable (Levels 1 and 2) inputs are generally assigned values on the basis of actual transactions. Securities valued on the basis of pricing models with significant unobservable inputs or nonbinding broker quotes are classified as Level 3. The Company performs quarterly analyses on the prices it receives from third parties to determine whether the prices are reasonable estimates of fair value, including confirming the fair values of these securities through observable market prices using an alternative pricing source, as it is ultimately management’s responsibility to ensure that the fair values reflected in the Company’s consolidated financial statements are appropriate. If differences are noted in these analyses, the Company may obtain additional information from other pricing services to validate the quoted price. The Company bases all of its estimates of fair value for assets on the bid price, when available, as it represents what a third-party market participant would be willing to pay in an arm's length transaction. For securities not actively traded, third party pricing services may use quoted market prices of similar instruments or discounted cash flow analyses, incorporating inputs that are currently observable in the markets for similar securities. Inputs that are often used in the valuation methodologies include, but are not limited to, broker quotes, benchmark yields, credit spreads, default rates, and prepayment speeds. There were no adjustments to prices obtained from third party pricing services as of December 31, 2016 and 2015 that were material to the consolidated financial statements. These methods of valuation will only produce an estimate of fair value if there is objectively verifiable information to produce a valuation. If objectively verifiable information is not available, the Company would be required to produce an estimate of fair value using some of the same methodologies, making assumptions for market-based inputs that are unavailable. The Company's estimates of fair value for its financial liabilities are based on a combination of the variable interest rates for notes with similar durations to discount the projection of future payments on notes payable. The fair value measurements for notes payable have been determined to be Level 2. Each of the Company's insurance operating subsidiaries is a member of the Federal Home Loan Bank (FHLB) of San Francisco. Members are required to purchase stock in the FHLB in addition to maintaining collateral deposits that back any funds advanced. Investment in FHLB stock is recorded at cost, as purchases and sales of these securities are at par value with the issuer. The stock is considered a restricted security and is periodically evaluated for impairment based on the ultimate recovery of par value. Due to the nature of FHLB stock, its carrying value approximates fair value and was determined by the Company to be Level 3. Certain of the Company's privately placed asset-backed securities (ABS) are designated as level 3 primarily due to restrictions on resale. Third party pricing based on actual transactions are typically not available for these securities due to the limited nature of observable pricing inputs. The following table presents the items in the Company's Consolidated Balance Sheets that are stated at fair value and the corresponding fair value measurements. December 31, 2016 December 31, 2015 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 (in millions) Fixed maturity securities U.S. Treasuries $ — $ 127.4 $ — $ — $ 120.2 $ — U.S. Agencies — 12.8 — — 24.4 — States and municipalities — 851.6 — — 854.5 — Corporate securities — 956.7 — — 925.3 — Residential mortgage-backed securities — 258.0 — — 237.9 — Commercial mortgage-backed securities — 95.5 — — 80.3 — Asset-backed securities — 35.4 7.0 — 45.9 — Total fixed maturity securities $ — $ 2,337.4 $ 7.0 $ — $ 2,288.5 $ — Equity securities Industrial and miscellaneous $ 167.2 $ — $ — $ 178.4 $ — $ — Non-redeemable preferred (FHLB stock) — — 4.9 — — — Other 20.1 — — 20.3 — — Total equity securities $ 187.3 $ — $ 4.9 $ 198.7 $ — $ — Short-term investments $ — $ 16.0 $ — $ — $ — $ — Certain cash equivalents, principally money market securities, are measured at fair value using the net asset value (NAV) per share. The following table presents cash equivalents at NAV and total cash and cash equivalents carried at fair value on the Company's Consolidated Balance Sheets. December 31, 2016 December 31, 2015 Cash and cash equivalents at fair value $ 9.7 $ 56.6 Cash equivalents measured at NAV, which approximates fair value 57.5 — Total cash and cash equivalents $ 67.2 $ 56.6 The following table provides a reconciliation of the beginning and ending balances that are measured using Level 3 inputs for the year ended December 31, 2016 . Level 3 Securities (in millions) Beginning balance, January 1, 2016 $ — Purchases 11.9 Ending balance, December 31, 2016 $ 11.9

Investments

Investments	12 Months Ended
	Dec. 31, 2016
Investments [Abstract]
Investments	Investments The cost or amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the Company’s investments were as follows: Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value At December 31, 2016 (in millions) Fixed maturity securities U.S. Treasuries $ 124.1 $ 3.5 $ (0.2 ) $ 127.4 U.S. Agencies 11.9 0.9 — 12.8 States and municipalities 833.0 24.7 (6.1 ) 851.6 Corporate securities 942.3 18.9 (4.5 ) 956.7 Residential mortgage-backed securities 255.9 4.7 (2.6 ) 258.0 Commercial mortgage-backed securities 96.1 0.4 (1.0 ) 95.5 Asset-backed securities 42.6 — (0.2 ) 42.4 Total fixed maturity securities 2,305.9 53.1 (14.6 ) 2,344.4 Equity securities Industrial and miscellaneous 100.5 67.4 (0.7 ) 167.2 Non-redeemable preferred (FHLB stock) 4.9 — — 4.9 Other 10.7 9.4 — 20.1 Total equity securities 116.1 76.8 (0.7 ) 192.2 Short-term investments 16.0 — — 16.0 Total investments $ 2,438.0 $ 129.9 $ (15.3 ) $ 2,552.6 At December 31, 2015 Fixed maturity securities U.S. Treasuries $ 116.4 $ 3.9 $ (0.1 ) $ 120.2 U.S. Agencies 23.0 1.4 — 24.4 States and municipalities 809.4 45.1 — 854.5 Corporate securities 913.4 19.9 (8.0 ) 925.3 Residential mortgage-backed securities 231.8 7.1 (1.0 ) 237.9 Commercial mortgage-backed securities 81.1 0.2 (1.0 ) 80.3 Asset-backed securities 46.0 — (0.1 ) 45.9 Total fixed maturity securities 2,221.1 77.6 (10.2 ) 2,288.5 Equity securities Industrial and miscellaneous 126.0 56.8 (4.4 ) 178.4 Other 11.5 9.0 (0.2 ) 20.3 Total equity securities 137.5 65.8 (4.6 ) 198.7 Total investments $ 2,358.6 $ 143.4 $ (14.8 ) $ 2,487.2 The amortized cost and estimated fair value of the Company's fixed maturity securities at December 31, 2016 , by contractual maturity, are shown below. Expected maturities differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Amortized Cost Estimated Fair Value (in millions) Due in one year or less $ 136.1 $ 137.4 Due after one year through five years 896.8 918.6 Due after five years through ten years 613.4 625.7 Due after ten years 265.0 266.8 Mortgage and asset-backed securities 394.6 395.9 Total $ 2,305.9 $ 2,344.4 The following is a summary of investments that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 months or greater as of December 31, 2016 and 2015 . December 31, 2016 December 31, 2015 Estimated Fair Value Gross Unrealized Losses Number of Issues Estimated Fair Value Gross Unrealized Losses Number of Issues Less than 12 months: (dollars in millions) Fixed maturity securities U.S. Treasuries $ 33.3 $ (0.2 ) 14 $ 27.4 $ (0.1 ) 20 States and municipalities 200.9 (6.1 ) 50 — — — Corporate securities 289.5 (4.1 ) 101 328.4 (4.7 ) 122 Residential mortgage-backed securities 137.5 (2.6 ) 51 50.5 (0.8 ) 24 Commercial mortgage-backed securities 48.0 (1.0 ) 21 51.5 (1.0 ) 22 Asset-backed securities 30.1 (0.2 ) 20 34.1 — 27 Total fixed maturity securities 739.3 (14.2 ) 257 491.9 (6.6 ) 215 Equity securities 13.6 (0.6 ) 28 35.8 (4.6 ) 45 Total less than 12 months $ 752.9 $ (14.8 ) 285 $ 527.7 $ (11.2 ) 260 12 months or greater: Fixed maturity securities Corporate securities $ 15.2 $ (0.4 ) 5 $ 34.6 $ (3.3 ) 15 Residential mortgage-backed securities — — — 7.1 (0.2 ) 25 Asset-backed securities — — — 11.1 (0.1 ) 4 Total fixed maturity securities 15.2 (0.4 ) 5 52.8 (3.6 ) 44 Equity securities 1.7 (0.1 ) 5 — — — 12 months or greater $ 16.9 $ (0.5 ) 10 $ 52.8 $ (3.6 ) 44 Total available-for-sale: Fixed maturity securities U.S. Treasuries $ 33.3 $ (0.2 ) 14 $ 27.4 $ (0.1 ) 20 States and municipalities 200.9 (6.1 ) 50 — — — Corporate securities 304.7 (4.5 ) 106 363.0 (8.0 ) 137 Residential mortgage-backed securities 137.5 (2.6 ) 51 57.6 (1.0 ) 49 Commercial mortgage-backed securities 48.0 (1.0 ) 21 51.5 (1.0 ) 22 Asset-backed securities 30.1 (0.2 ) 20 45.2 (0.1 ) 31 Total fixed maturity securities 754.5 (14.6 ) 262 544.7 (10.2 ) 259 Equity securities 15.3 (0.7 ) 33 35.8 (4.6 ) 45 Total available-for-sale $ 769.8 $ (15.3 ) 295 $ 580.5 $ (14.8 ) 304 The Company determined that unrealized losses on fixed maturities at December 31, 2016 , 2015 , and 2014 were primarily the result of changes in prevailing interest rates and not the credit quality of the issuers. The fixed maturity securities whose fair value was less than amortized cost were not determined to be other-than-temporarily impaired given the lack of severity and duration of the impairment, the credit quality of the issuers, the Company’s intent to not sell the securities, and a determination that it is not more likely than not that the Company will be required to sell the securities until fair value recovers to above amortized cost, or principal value upon maturity. The Company recognized total impairments of $5.8 million (consisting of 37 securities), $17.2 million (consisting of 27 securities) and $0.5 million (consisting of seven securities) during the years ended December 31, 2016 , 2015 , and 2014 , respectively. The other-than-temporary impairments recognized during these years related to equity securities were the result of the Company's intent to sell and/or the severity and duration of the change in fair values of these securities, primarily due to the downturn in the energy sector that occurred during the fourth quarter of 2015 and the first quarter of 2016. Certain unrealized losses on equity securities were not considered to be other-than-temporary due to the financial condition and near-term prospects of the issuers, and the Company's intent to hold the securities until fair value recovers to above cost. Net realized gains on investments and the change in unrealized gains (losses) on fixed maturity and equity securities are determined on a specific-identification basis and were as follows: Years Ended December 31, 2016 2015 2014 Net realized gains (losses) on investments (in millions) Fixed maturity securities Gross gains $ 1.9 $ 0.5 $ 1.1 Gross losses (0.7 ) (0.4 ) — Net realized gains on fixed maturity securities $ 1.2 $ 0.1 $ 1.1 Equity securities Gross gains $ 16.6 $ 8.1 $ 15.7 Gross losses (6.6 ) (18.9 ) (0.5 ) Net realized gains (losses) on equity securities $ 10.0 $ (10.8 ) $ 15.2 Total $ 11.2 $ (10.7 ) $ 16.3 Change in unrealized gains (losses) Fixed maturity securities $ (28.9 ) $ (22.2 ) $ 23.1 Equity securities 14.9 (13.7 ) 2.2 Total $ (14.0 ) $ (35.9 ) $ 25.3 Net investment income was as follows: Years Ended December 31, 2016 2015 2014 (in millions) Fixed maturity securities $ 68.5 $ 68.8 $ 70.7 Equity securities 7.4 5.9 4.2 Cash equivalents and restricted cash 0.4 0.1 0.1 Gross investment income 76.3 74.8 75.0 Investment expenses (3.1 ) (2.6 ) (2.6 ) Net investment income $ 73.2 $ 72.2 $ 72.4 The Company is required by various state laws and regulations to hold securities or letters of credit in depository accounts with certain states in which it does business. As of December 31, 2016 and 2015 , securities having a fair value of $1,009.7 million and $881.2 million , respectively, were on deposit. These laws and regulations govern not only the amount but also the type of securities that are eligible for deposit. Certain reinsurance contracts require Company funds to be held in trust for the benefit of the ceding reinsurer to secure the outstanding liabilities assumed by the Company. The fair value of fixed maturity securities and restricted cash and cash equivalents held in trust for the benefit of the ceding reinsurers at December 31, 2016 and 2015 was $27.2 million and $32.7 million , respectively.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2016
Property and Equipment [Abstract]
Property, Plant and Equipment Disclosure	Property and Equipment Property and equipment consists of the following: As of December 31, 2016 2015 (in millions) Furniture and equipment $ 2.3 $ 2.3 Leasehold improvements 4.3 4.3 Computers and software 59.0 56.7 Automobiles 1.2 1.2 Property and equipment, gross 66.8 64.5 Accumulated amortization and depreciation (44.6 ) (39.6 ) Property and equipment, net $ 22.2 $ 24.9 Depreciation and amortization expenses related to property and equipment for the years ended December 31, 2016 , 2015 , and 2014 were $8.2 million , $7.8 million , and $6.3 million , respectively. Internally developed software costs of $1.3 million and $1.2 million were capitalized during each of the years ended December 31, 2016 and 2015 , respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Taxes [Abstract]
Income Taxes	Income Taxes The Company files a consolidated federal income tax return. The insurance subsidiaries pay premium taxes on gross premiums written in lieu of some states' income or franchise taxes. The Company's provision for income taxes consisted of the following: Years Ended December 31, 2016 2015 2014 Current tax expense: (in millions) Federal $ 20.3 $ 9.5 $ 6.3 State 0.3 1.1 0.1 Total current tax expense 20.6 10.6 6.4 Deferred federal tax expense (benefit) 13.4 (5.6 ) (0.5 ) Income tax expense $ 34.0 $ 5.0 $ 5.9 The difference between the statutory federal tax rate of 35% and the Company's effective tax rate on net income before income taxes as reflected in the Consolidated Statements of Comprehensive Income was as follows: Years Ended December 31, 2016 2015 2014 (in millions) Expense computed at statutory rate $ 49.3 $ 34.8 $ 37.3 Tax-advantaged investment income (8.5 ) (8.6 ) (8.8 ) Pre-Privatization reserve adjustments, excluding LPT — (15.3 ) (3.6 ) LPT deferred gain amortization (4.7 ) (4.9 ) (8.4 ) LPT Reserve Adjustment (1.1 ) (2.2 ) (10.9 ) Other (1.0 ) 1.2 0.3 Income tax expense $ 34.0 $ 5.0 $ 5.9 On January 1, 2000, EICN assumed the assets, liabilities, and operations of the Fund pursuant to legislation passed in the 1999 Nevada Legislature (the Privatization). Prior to the Privatization, the Fund was a part of the State of Nevada and therefore was not subject to federal income tax; accordingly, it did not take an income tax deduction with respect to the establishment of its unpaid loss and LAE reserves. Due to favorable loss experience after the Privatization, it was determined that certain of the pre-Privatization unpaid loss and LAE reserves assumed by EICN as part of the Privatization were no longer necessary and the unpaid loss and LAE reserves were reduced accordingly. Such downward adjustments of pre-Privatization unpaid loss reserves increased GAAP net income by $15.3 million and $3.6 million for the years ended December 31, 2015 and 2014 , respectively, but did not increase taxable income. There were no downward adjustments of pre-Privatization unpaid loss reserves for the year ended December 31, 2016 . Downward adjustments of pre-Privatization unpaid loss reserves, excluding the LPT, were $56.3 million and $13.1 million for the years ended December 31, 2015 and 2014 , respectively. The LPT Reserve Adjustments for the years ended December 31, 2016 , 2015 , and 2014 increased GAAP net income by $3.1 million , $6.4 million , and $31.1 million , respectively, but did not increase taxable income. The LPT Contingent Commission Adjustments increased net income by $1.8 million , $2.6 million , and $10.8 million during 2016 , 2015 , and 2014 , respectively, but did not increase taxable income. As of December 31, 2016 and 2015 , the Company had no unrecognized tax benefits. The Company paid (received) $13.7 million , $12.7 million and $(1.1) million in income taxes during the years ended December 31, 2016 , 2015 , and 2014 , respectively. Tax years 2013 through 2016 remained open and are subject to full examination by the federal taxing authority. The significant components of deferred income taxes, net, were as follows as of December 31: 2016 2015 Deferred Tax Deferred Tax Assets Liabilities Assets Liabilities (in millions) Unrealized capital gains, net $ — $ 40.1 $ — $ 45.0 Deferred policy acquisition costs — 15.7 — 15.7 Intangible assets — 2.9 — 3.0 Loss reserve discounting for tax reporting 51.7 — 56.3 — Unearned premiums 20.9 — 20.9 — Allowance for bad debt 3.4 — 4.3 — Stock-based compensation 4.4 — 4.1 — Accrued liabilities 8.1 — 8.4 — Minimum tax credit 27.8 — 28.0 — Net operating loss carryforward — — 8.7 — Other 9.7 7.9 8.4 7.5 Total $ 126.0 $ 66.6 $ 139.1 $ 71.2 Deferred income taxes, net $ 59.4 $ 67.9 During the year ended December 31, 2016 , the Company fully utilized its net operating loss carryforward that existed as of December 31, 2015 . As of December 31, 2016 and 2015 , the Company had a minimum tax credit of $27.8 million and $28.0 million , respectively, that may be carried forward indefinitely. Deferred tax assets are required to be reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax asset will not be realized. Realization of the deferred income tax asset is dependent on the Company generating sufficient taxable income in future years as the deferred income tax charges become deductible for tax reporting purposes. Although realization is not assured, management believes that it is more likely than not that the net deferred income tax asset will be realized.

Liability for Unpaid Losses and

Liability for Unpaid Losses and Loss Adjustment Expenses	12 Months Ended
	Dec. 31, 2016
Liability for Unpaid Losses and Loss Adjustment Expenses [Abstract]
Liability for Unpaid Losses and Loss Adjustment Expenses	Liability for Unpaid Losses and Loss Adjustment Expenses Accounting for workers' compensation insurance requires the Company to estimate the liability for the expected ultimate cost of unpaid losses and LAE (loss reserves) as of a balance sheet date. Loss reserve estimates are inherently uncertain because the ultimate amount the Company will pay for many of the claims it has incurred as of the balance sheet date will not be known for many years. The estimate of loss reserves is intended to equal the difference between the expected ultimate losses and LAE of all claims that have occurred as of a balance sheet date and amounts already paid. The Company establishes loss reserves based on its own analysis of emerging claims experience and environmental conditions in its markets and review of the results of various actuarial projections. The Company's aggregate carried reserve for unpaid losses and LAE is the sum of its reserves for each accident year and represents its best estimate of outstanding loss reserves. The amount by which estimated losses in the aggregate differ from those previously estimated for a specific time period is known as reserve “development.” Reserve development is unfavorable when losses ultimately settle for more than the amount reserved or subsequent estimates indicate a basis for reserve increases on open claims, causing the previously estimated loss reserves to be ''deficient.'' Reserve development is favorable when estimates of ultimate losses indicate a decrease in established reserves, causing the previously estimated loss reserves to be ''redundant.'' Development is reflected in the Company's operating results through an adjustment to incurred losses and LAE during the period in which it is recognized. Although claims for which reserves are established may not be paid for several years or more, the Company does not discount loss reserves in its financial statements for the time value of money, in accordance with GAAP. The three main components of reserves for unpaid losses and LAE are case reserves, incurred but not reported (IBNR) loss reserves, and LAE reserves. When claims are reported, the Company establishes individual estimates of the ultimate cost of each claim (case reserves). These case reserves are continually monitored and revised in response to new information and for amounts paid. IBNR is an actuarial estimate of future payments on claims that have occurred but have not yet been reported. In addition to this provision for late reported claims, the Company also estimates and makes a provision for the extent to which the case reserves on known claims may develop and for additional payments on closed claims, known as “reopening.” IBNR reserves apply to the entire body of claims arising from a specific time period, rather than a specific claim. Most of the Company's IBNR reserves relate to estimated future claim payments on recorded open claims. LAE reserves are the Company's estimate of the future expenses of investigating, administering, and settling claims that will be paid to manage claims that have occurred, including legal expenses. LAE reserves are established in the aggregate, rather than on a claim-by-claim basis. LAE reserves are categorized between defense and cost containment, and adjusting and other. A portion of the Company's obligations for losses and LAE are ceded to unaffiliated reinsurers. The amount of reinsurance that will be recoverable on its losses and LAE reserves includes both the reinsurance recoverable from excess of loss reinsurance contracts, as well as reinsurance recoverable under the terms of the LPT Agreement. The Company uses actuarial methods to analyze and estimate the aggregate amount of unpaid losses and LAE. Management considers the results of various actuarial projection methods and their underlying assumptions, among other factors, in establishing reserves for unpaid losses and LAE. Judgment is required in the actuarial estimation of loss reserves, including the selection of various actuarial methodologies to project the ultimate cost of claims. Specifically, judgment is required in the following areas: the selection of projection parameters based on historical company data; the use of industry data and other benchmarks; the identification and quantification of potential changes in parameters from historical levels to current and future levels due to changes in future claims development expectations; and the weighting of differing reserve indications resulting from alternative methods and assumptions. The following table represents a reconciliation of changes in the liability for unpaid losses and LAE. Years Ended December 31, 2016 2015 2014 (in millions) Unpaid losses and LAE at beginning of period $ 2,347.5 $ 2,369.7 $ 2,330.5 Less reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE 628.2 669.5 743.1 Net unpaid losses and LAE at beginning of period 1,719.3 1,700.2 1,587.4 Losses and LAE, net of reinsurance, incurred in: Current year 452.9 456.9 503.8 Prior years (18.4 ) (7.2 ) 4.6 Total net losses and LAE incurred during the period 434.5 449.7 508.4 Paid losses and LAE, net of reinsurance, related to: Current year 78.7 75.4 75.9 Prior years 354.1 355.2 319.7 Total net paid losses and LAE during the period 432.8 430.6 395.6 Ending unpaid losses and LAE, net of reinsurance 1,721.0 1,719.3 1,700.2 Reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE 580.0 628.2 669.5 Unpaid losses and LAE at end of period $ 2,301.0 $ 2,347.5 $ 2,369.7 Total net losses and LAE included in the above table excludes the impact of the amortization of the Deferred Gain and LPT Reserve Adjustments (Note 10 ). In 2016, the Company had $18.4 million of favorable prior accident year loss development, which included $17.0 million of favorable development on its voluntary risk business and $1.4 million of favorable development related to its assigned risk business. In 2015, the Company had $7.2 million of favorable prior accident year loss development, which included $9.0 million of favorable prior accident year loss development on its voluntary risk business, which was partially offset by $1.8 million of unfavorable loss development related to its assigned risk business. In 2014, the increase in the estimate of incurred losses and LAE attributable to insured events in prior years was primarily related to the Company's assigned risk business. The favorable prior accident year loss development in 2016 and 2015 was the result of the Company's determination that adjustments were necessary to reflect observed favorable paid loss trends in each of these years. Paid loss trends have been impacted by cost savings associated with accelerated claims settlement activity that began in 2014 and continued through 2016. In California, where the Company's operations began in 2002, the actuaries' and management's initial expectations of ultimate losses and patterns of loss emergence and payment were based on benchmarks derived from analyses of historical insurance industry data in California. No historical data from the Company's California insurance subsidiary existed prior to July 1, 2002; however, some historical data was available for the prior years for some of the market segments the Company entered in California, but was limited as to the number of loss reserve evaluation points available. The industry-based benchmarks were judgmentally adjusted for the anticipated impact of significant environmental changes, specifically the enactment of major changes to the statutory workers' compensation benefit structure and the manner in which claims are administered and adjudicated in California. The actual emergence and payment of claims by the Company's California insurance subsidiary have been more favorable than those initial expectations through 2008, due in part to the enactment of the major changes in the California workers' compensation environment. The Company's recent loss experience, from 2010 through 2016, indicates an upward trend in medical and indemnity costs that are reflected in its loss reserves; however, the Company's indemnity claims frequency (the number of claims expressed as a percentage of payroll) decreased year-over-year for the past three years. The Company's reserve estimates assume that increasing medical cost trends will continue and will impact the Company's long-term claims costs and loss reserves. The Company continues to develop its own loss experience in California and will rely more on its experience and less on historical industry data in projecting its reserve requirements as such data becomes available. As the actual experience of the Company emerges, it will continue to evaluate prior estimates, which may result in additional adjustments in reserves. In Nevada, the Company has compiled a lengthy history of workers' compensation claims payment patterns based on the business of the Fund and EICN, but the emergence and payment of claims in recent years has been more favorable than in the long-term history in Nevada with the Fund. The expected patterns of claim payments and emergence used in the projection of the Company's ultimate claim payments are based on both the long and short-term historical paid data. In recent evaluations, claim patterns have continued to emerge in a manner consistent with short-term historical data. Consequently, for California and Nevada, the Company has relied more heavily on claim projection patterns observed in recent years. Loss reserves shown in the Company's Consolidated Balance Sheets are net of $28.1 million and $26.8 million for anticipated subrogation recoveries as of December 31, 2016 and 2015 , respectively. The Company compiles and aggregates its claims data by grouping the claims according to the year in which the claim occurred (“accident year”) when analyzing claim payment and emergence patterns and trends over time. For the purposes of defining claims frequency, the number of reported claims includes any claim that has case reserves and/or loss and LAE payments associated with them. The Company analyzed the usefulness of disaggregation of its results and determined the characteristics associated with the policies and the related unpaid loss reserves, incurred losses, and payment patterns are similar in nature. As such, the following tables show the Company's historical incurred and cumulative paid losses and LAE development, net of reinsurance, as well as IBNR loss reserves and the number of reported claims on an aggregated basis as of December 31, 2016 for each of the previous 10 accident years. Incurred Losses and LAE, Net of Reinsurance Years Ended December 31, As of December 31, 2016 Accident Year 2007 (1) 2008 (1) 2009 (1) 2010 (1) 2011 (1) 2012 (1) 2013 (1) 2014 (1) 2015 (1) 2016 IBNR Cumulative number of reported claims (in millions, except claims counts) 2007 $ 349.4 $ 341.8 $ 340.1 $ 340.3 $ 332.9 $ 332.7 $ 334.7 $ 334.6 $ 339.2 $ 346.6 $ 15.1 31,326 2008 315.9 315.3 317.8 329.2 329.5 335.1 336.9 343.8 341.4 16.2 28,082 2009 255.4 266.9 279.0 280.1 283.6 283.7 291.2 290.5 16.3 22,666 2010 204.9 224.4 228.1 246.1 250.2 262.0 259.9 23.8 18,533 2011 253.7 267.3 272.0 277.4 296.3 292.6 34.0 19,553 2012 348.8 359.9 360.9 386.4 388.2 60.5 25,930 2013 452.6 460.6 478.6 472.6 90.1 28,740 2014 463.4 445.8 432.9 107.4 28,231 2015 422.2 425.8 135.6 26,560 2016 419.0 226.1 21,239 Total $ 3,669.6 Cumulative Paid Losses and LAE, Net of Reinsurance Years Ended December 31, Accident Year 2007 (1) 2008 (1) 2009 (1) 2010 (1) 2011 (1) 2012 (1) 2013 (1) 2014 (1) 2015 (1) 2016 (in millions) 2007 $ 74.2 $ 165.3 $ 208.9 $ 236.7 $ 256.2 $ 270.0 $ 280.2 $ 288.3 $ 297.2 $ 302.3 2008 71.1 155.4 201.8 234.7 255.3 271.1 284.2 293.6 300.7 2009 59.0 130.6 174.1 202.0 219.3 232.1 242.3 249.5 2010 47.1 105.6 143.8 171.7 190.7 206.2 215.4 2011 47.4 115.1 162.6 193.8 217.5 230.1 2012 58.6 148.3 214.2 261.4 289.9 2013 68.5 184.4 263.8 317.4 2014 65.3 172.7 248.9 2015 65.5 174.5 2016 65.6 Total $ 2,394.2 All outstanding liabilities for unpaid losses and LAE prior to 2007, net of reinsurance 346.2 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 1,621.6 (1) Data presented for these calendar years is required supplementary information, which is unaudited The following table represents a reconciliation of claims development to the aggregate carrying amount of the liability for unpaid losses and LAE: December 31, 2016 (in millions) Liabilities for unpaid losses and LAE, net of reinsurance $ 1,621.6 Reinsurance recoverable on unpaid losses 580.0 Unallocated LAE 99.4 Total liability for unpaid losses and LAE $ 2,301.0 The following table presents the average annual percentage payout of incurred claims by age, net of reinsurance, as of December 31, 2016 and is presented as required supplementary information, which is unaudited: Average Annual Percentage Payout of Claims by Age, Net of Reinsurance Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 17.3 % 24.4 % 15.4 % 10.3 % 6.7 % 4.7 % 3.5 % 2.5 % 2.3 % 1.5 %

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2016
Reinsurance [Abstract]
Reinsurance	Reinsurance The Company purchases reinsurance from third parties in the normal course of its business in order to manage its exposures. The Company's reinsurance coverage is provided on both a quota share and excess of loss basis. The effects of reinsurance on the Company's written and earned premiums and on its losses and LAE incurred were as follows: Years Ended December 31, 2016 2015 2014 Written Earned Written Earned Written Earned (in millions) Direct premiums $ 691.0 $ 691.0 $ 684.9 $ 686.0 $ 686.8 $ 684.3 Assumed premiums 10.4 10.6 12.8 12.8 10.9 10.3 Gross premiums 701.4 701.6 697.7 698.8 697.7 694.6 Ceded premiums (6.8 ) (6.8 ) (8.4 ) (8.4 ) (10.1 ) (10.1 ) Net premiums $ 694.6 $ 694.8 $ 689.3 $ 690.4 $ 687.6 $ 684.5 Ceded losses and LAE incurred $ 0.1 $ 10.1 $ 17.2 Ceded losses and LAE incurred includes the amortization of the Deferred Gain, LPT Reserve Adjustments, and LPT Contingent Commission Adjustments. Excess of Loss Reinsurance The Company has consistently maintained excess of loss reinsurance coverage to protect it against the impact of large and/or catastrophic losses in its workers' compensation business. The Company currently maintains reinsurance for losses from a single occurrence or catastrophic event in excess of $10.0 million and up to $200.0 million , subject to certain exclusions. This current reinsurance program is effective July 1, 2016 through June 30, 2017 . The coverage under the Company's annual reinsurance programs that ended July 1, 2016 and 2015 was $193.0 million and $195.0 million , in excess of its $7.0 million and $5.0 million retention on a per occurrence basis, respectively. The reinsurance coverage includes coverage for acts of terrorism, excluding nuclear, biological, chemical, and radiological events. Any liability outside the coverage limits of the reinsurance program is retained by the Company. LPT Agreement Recoverables from reinsurers on unpaid losses and LAE amounted to $580.0 million and $628.2 million at December 31, 2016 and 2015 , respectively. At each of December 31, 2016 and 2015 , $465.5 million and $498.0 million , respectively, of those recoverables was related to the LPT Agreement that was entered into in 1999 by the Fund and assumed by EICN. Under the LPT Agreement, substantially all of the Fund's losses and LAE on claims incurred prior to July 1, 1995, have been ceded to three unaffiliated reinsurers on a 100% quota share basis. Investments have been placed in trust by the three reinsurers as security for payment of the reinsured claims. Under the LPT Agreement, initially $1.5 billion in liabilities for the incurred but unpaid losses and LAE related to claims incurred prior to July 1, 1995, were reinsured for consideration of $775.0 million . The LPT Agreement provides coverage up to $2.0 billion . Through December 31, 2016 , the Company has paid losses and LAE claims totaling $722.7 million related to the LPT Agreement. The Company amortized $11.7 million , $11.4 million , and $13.1 million of the Deferred Gain for the years ended December 31, 2016 , 2015 , and 2014 , respectively. Additionally, the Deferred Gain was reduced by $3.1 million , $6.4 million and $31.1 million for the years ended December 31, 2016 , 2015 , and 2014 , respectively, due to favorable LPT Reserve Adjustments and by $1.8 million , $2.6 million , and $10.8 million for the years ended December 31, 2016 , 2015 , and 2014 , respectively, due to favorable LPT Contingent Commission Adjustments (Note 2 ).

Notes Payable

Notes Payable	12 Months Ended
	Dec. 31, 2016
Notes Payable [Abstract]
Notes Payable	Notes Payable Notes payable is comprised of the following: December 31, 2016 2015 (in millions) Dekania Surplus Note, due April 30, 2034 $ 10.0 $ 10.0 ICONS Surplus Note, due May 26, 2034 12.0 12.0 Alesco Surplus Note, due December 15, 2034 10.0 10.0 Balance $ 32.0 $ 32.0 EPIC has a $10.0 million surplus note to Dekania CDO II, Ltd. issued as part of a pooled transaction. The note matures in 2034 and became callable by the Company in 2009 . The terms of the note provide for quarterly interest payments at a rate 425 basis points in excess of the 90-day LIBOR. Both the payment of interest and repayment of the principal under this note and the surplus notes described in the succeeding two paragraphs are subject to the prior approval of the Florida Department of Financial Services. Interest paid during each of the years ended December 31, 2016 , 2015 , and 2014 was $0.5 million . Interest accrued as of December 31, 2016 and 2015 was $0.1 million . EPIC has a $12.0 million surplus note to ICONS, Inc. issued as part of a pooled transaction. The note matures in 2034 and became callable by the Company in 2009 . The terms of the note provide for quarterly interest payments at a rate 425 basis points in excess of the 90-day LIBOR. Interest paid during each of the years ended December 31, 2016 , 2015 , and 2014 was $0.6 million , $0.6 million and $0.5 million , respectively. Interest accrued as of December 31, 2016 and 2015 was $0.1 million . EPIC has a $10.0 million surplus note to Alesco Preferred Funding V, LTD issued as part of a pooled transaction. The note matures in 2034 and became callable by the Company in 2009 . The terms of the note provide for quarterly interest payments at a rate 405 basis points in excess of the 90-day LIBOR. Interest paid during each of the years ended December 31, 2016 , 2015 , and 2014 was $0.5 million , $0.4 million , and $0.4 million , respectively. Interest accrued as of December 31, 2016 and 2015 was less than $0.1 million . In 2010, the Company entered into a credit facility, under which the Company was provided with: (a) $100.0 million line of credit through December 31, 2011; (b) $90.0 million line of credit from January 1, 2012 through December 31, 2012; (c) $80.0 million line of credit from January 1, 2013 through December 31, 2013; (d) $70.0 million line of credit from January 1, 2014 through December 31, 2014; and (e) $60.0 million line of credit from January 1, 2015 through December 31, 2015. Amounts outstanding bore interest at a rate equal to, at our option: (a) a fluctuating rate of 1.75% above prime rate or (b) a fixed rate that is 1.75% above the LIBOR rate then in effect. Interest paid during the years ended December 31, 2015 and 2014 totaled $1.3 million and $1.4 million , respectively. In accordance with the terms of the contract, the remaining principal balance of $60.0 million was repaid on the credit facility in 2015. Principal payment obligations on notes payable outstanding at December 31, 2016 , were as follows: Year Principal Due (in millions) 2017 - 2021 $ — Thereafter 32.0 Total $ 32.0

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies [Abstract]
Commitments and Contingencies Disclosure	Commitments and Contingencies Leases The Company leases office facilities and certain equipment under operating and capital leases. Most leases have renewal options, typically with increased rental rates during the option period. Certain of these leases contain options to purchase the property at amounts that approximate fair market value; other leases contain options to purchase at a bargain purchase price. At December 31, 2016 , the remaining lease terms expire over the next six years . The future lease payments for the next five years on these non-cancelable operating and capital leases at December 31, 2016 , were as follows: Year Operating Leases Capital Leases (in millions) 2017 $ 5.1 $ 0.3 2018 3.7 0.2 2019 3.1 0.1 2020 2.5 0.1 2021 1.1 0.1 Thereafter 0.1 — Total $ 15.6 $ 0.8 Included in the future minimum capital lease payments are future interest charges of $0.1 million . Facilities rent expense was $4.9 million , $4.9 million , and $4.8 million for the years ended December 31, 2016 , 2015 , and 2014 , respectively. Property held under capital leases is included in property and equipment as follows: Asset Class 2016 2015 (in millions) Computers and software $ — $ 0.4 Automobiles 1.2 1.2 1.2 1.6 Accumulated amortization (0.6 ) (1.0 ) Total $ 0.6 $ 0.6 Contingencies Surrounding Insurance Assessments All of the states where the Company's insurance subsidiaries are licensed to transact business require property and casualty insurers doing business within the respective state to pay various insurance assessments. The Company accrues a liability for estimated insurance assessments as direct premiums are written, losses are recorded, or as other events occur in accordance with various states' laws and regulations, and defers these costs and recognizes them as an expense as the related premiums are earned. The Company had an accrued liability for guaranty fund assessments, second injury funds assessments, and other insurance assessments totaling $18.6 million and $22.0 million as of December 31, 2016 and 2015 , respectively. These liabilities are generally expected to be paid over one to eighty year periods based on individual state's regulations. The Company also recorded an asset of $21.6 million and $21.4 million , as of December 31, 2016 and 2015 , respectively, for prepaid policy charges still to be collected in the future from policyholders, or assessments that may be recovered through a reduction in future premium taxes in certain states. These assets are expected to be realized over one to ten year periods in accordance with their type and individual state's regulations.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2016
Stockholders' Equity Attributable to Parent [Abstract]
Treasury Stock	Stockholders' Equity Stock Repurchase Programs On February 16, 2016, the Board of Directors authorized a share repurchase program for up to $50.0 million of the Company's common stock from February 22, 2016 through February 22, 2018 (the 2016 Program). The Company expects that its common stock may be purchased at prevailing market prices through a variety of methods, including open market or private transactions, in accordance with applicable laws and regulations and as determined by management. The timing and actual number of shares repurchased will depend on a variety of factors, including the share price, corporate and regulatory requirements, and other market and economic conditions. Repurchases under the 2016 Program may be commenced, modified, or suspended from time-to-time without prior notice, and the 2016 Program may be suspended or discontinued at any time. Through December 31, 2016 , the Company has repurchased a total of 724,381 shares of common stock at an average price of $29.08 per share, including commissions, for a total of $21.1 million . Since the Company's initial public offering in January 2007 through December 31, 2016 , the Company has repurchased a total of 24,097,355 shares of common stock at an average cost per share of $15.92 , which is reported as treasury stock, at cost, on its Consolidated Balance Sheets.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2016
Stock-Based Compensation [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Employers Holdings, Inc. Amended and Restated Equity and Incentive Plan (the Plan) is administered by the Compensation Committee of the Board of Directors, which is authorized to grant, at its discretion, awards to officers, employees, non-employee directors, consultants, and independent contractors. The maximum number of common shares reserved for grants of awards under the Plan was 7,105,838 shares, prior to reductions for grants made. The Plan provides for the grant of stock options (both incentive stock options and nonqualified stock options), stock appreciation rights, shares of restricted stock, restricted stock units (RSUs), performance stock units (PSUs), and other stock-based awards. As of December 31, 2016 , the only incentive awards outstanding under the Plan were nonqualified stock options, RSUs, and PSUs. Compensation costs are recognized based on expected performance, if applicable, net of any estimated forfeitures on a straight-line basis over the employee requisite service periods. Forfeiture rates are based on historical experience and are adjusted in subsequent periods for differences in actual forfeitures from those estimated. Net stock-based compensation expense recognized in the Company's Consolidated Statements of Comprehensive Income was as follows: Years Ended December 31, 2016 2015 2014 Stock-based compensation expense related to: (in millions) Stock options $ 0.7 $ 1.0 $ 1.2 RSUs 1.9 2.0 1.9 PSUs 3.2 1.6 2.9 Total 5.8 4.6 6.0 Less: related tax benefit 2.0 1.6 2.1 Net stock-based compensation expense $ 3.8 $ 3.0 $ 3.9 Stock Options The fair value of the stock options granted is estimated using a Black-Scholes option pricing model that uses the assumptions noted in the following table. During the years ended December 31, 2016 , 2015 , and 2014 , the expected stock price volatility used to value the stock options granted in 2016 , 2015 , and 2014 was based on the volatility of the Company's historical stock price since February 2007. The expected term of the stock options granted in 2016 , 2015 , and 2014 was calculated using the 'plain-vanilla' calculation provided in the guidance of the Securities and Exchange Commission's Staff Accounting Bulletin No. 107. The dividend yield was calculated using amounts authorized by the Board of Directors. The risk-free interest rate is the yield on the grant date of the stock options of U.S. Treasury zero coupon securities with a maturity comparable to the expected term of the stock options. The Company anticipates issuing new shares of common stock upon the exercise of its outstanding stock options. The fair value of the stock options granted during the years ended December 31, 2016 , 2015 , and 2014 was calculated using the following weighted average assumptions: 2016 2015 2014 Expected volatility 38.0 % 38.0 % 39.0 % Expected life (in years) 4.8 4.8 4.8 Dividend yield 1.3 % 1.0 % 1.2 % Risk-free interest rate 1.4 % 1.6 % 1.6 % Weighted average grant date fair values of stock options granted $8.46 $7.63 $6.66 Changes in outstanding stock options for the year ended December 31, 2016 were as follows: Number of Stock Options Weighted-Average Exercise Price Weighted Average Remaining Contractual Life Stock options outstanding at December 31, 2013 1,546,898 $ 17.24 3.4 years Granted 141,744 20.87 6.2 years Exercised (120,494 ) 17.89 Expired (2,400 ) 17.00 Forfeited (44,458 ) 19.99 Stock options outstanding at December 31, 2014 1,521,290 17.45 2.9 years Granted 80,800 24.20 6.2 years Exercised (463,466 ) 16.43 Forfeited (17,079 ) 20.21 Stock options outstanding at December 31, 2015 1,121,545 18.31 2.8 years Granted 67,431 27.72 6.2 years Exercised (586,132 ) 16.39 Expired (6,075 ) 22.48 Forfeited (32,673 ) 24.35 Stock options outstanding at December 31, 2016 564,096 21.04 3.3 years Exercisable at December 31, 2016 380,703 19.57 2.4 years At December 31, 2016 , the Company had yet to recognize $1.1 million in deferred compensation related to stock option grants and expects to recognize these costs on a straight-line basis over the next 39 months . The fair value of stock options vested and the intrinsic value of outstanding and exercisable stock options as of December 31, were as follows: 2016 2015 2014 (in millions) Fair value of stock options vested $ 0.8 $ 1.3 $ 1.6 Intrinsic value of outstanding stock options 10.6 10.1 9.2 Intrinsic value of exercisable stock options 7.6 8.5 7.8 The intrinsic value of stock options exercised was $7.6 million , $4.0 million , and $0.5 million for the years ended December 31, 2016 , 2015 , and 2014 . RSUs The Company has awarded RSUs to non-employee members of the Board of Directors and certain employees of the Company. The RSUs awarded to non-employee members of the Board of Directors generally vest on the first anniversary of the award date. RSU grants allow each non-employee Director to decide whether to defer settlement of the RSUs until six months after termination of Board service or settle the RSUs at vesting. Dividend equivalents are granted to Directors who elected to defer settlement of the RSUs after the grants vested. RSUs awarded to employees of the Company have a service vesting period of approximately four years from the date awarded and vest 25% on or after each of the subsequent four anniversaries of such date . These RSUs are subject to accelerated vesting in certain limited circumstances, such as: retirement, death or disability of the holder, or in connection with a change of control of the Company. Changes in outstanding RSUs for the year ended December 31, 2016 were as follows: Number of RSUs Weighted Average Grant Date Fair Value RSUs outstanding at December 31, 2013 358,346 $ 18.44 Granted 87,396 21.02 Forfeited (16,690 ) 20.18 Vested (122,185 ) 18.26 RSUs outstanding at December 31, 2014 306,867 19.15 Granted 112,048 24.19 Forfeited (7,749 ) 20.99 Vested (92,133 ) 19.74 RSUs outstanding at December 31, 2015 319,033 20.71 Granted 100,218 28.20 Forfeited (21,872 ) 24.87 Vested (72,995 ) 21.56 RSUs outstanding at December 31, 2016 324,384 22.55 Vested but unsettled RSUs at December 31, 2016 140,587 18.54 At December 31, 2016 , the Company had yet to recognize $3.5 million in deferred compensation related to outstanding RSUs and expects to recognize these costs on a straight-line basis over the next 39 months . The grant date fair value of RSUs vested and the intrinsic value of vested RSUs for the years ended December 31, were as follows: 2016 2015 2014 (in millions) Grant date fair value of RSUs vested $ 1.6 $ 1.7 $ 2.2 Intrinsic value of RSUs vested 2.1 2.2 2.7 The intrinsic value of outstanding RSUs was $12.8 million , $8.7 million , and $7.2 million at December 31, 2016 , 2015 , and 2014 . PSUs The Company has awarded PSUs to certain employees of the Company as follows: Date of Grant Target Number Awarded Fair Value on Date of Grant Aggregate Fair Value on Date of Grant (in millions) March 2014 (1) 125,340 $ 20.87 $ 2.6 March 2015 (2) 110,000 24.20 2.7 March 2016 (2) 97,236 27.72 2.7 (1) The PSUs granted in 2014 have a performance period of three years and are subject to certain performance goals, based on the Company's statutory combined ratio, with payouts that range from 0% to 200% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level. (2) The PSUs awarded in March 2015 and 2016 were awarded to certain employees of the Company and have a performance period of two years followed by an additional one year vesting period. The PSU awards are subject to certain performance goals with payouts that range from 0% to 200% of the target awards. The values shown in the table represent the aggregate number of PSUs awarded at the target level. At December 31, 2016 , the Company had yet to recognize $4.7 million in deferred compensation related to PSU grants and expects to recognize these costs on a straight-line basis over the next 24 months . This is based on the expectation of the Company achieving an 89% of target rate for the 2014 PSUs, a 200% of target rate for the 2015 PSUs, and a 182% of target rate for the 2016 PSUs.

Statutory Matters

Statutory Matters	12 Months Ended
	Dec. 31, 2016
Stautory Matters [Abstract]
Statutory Financial Data Disclosure	Statutory Matters Statutory Financial Data The combined capital stock, surplus, and net income of the Company's insurance subsidiaries (EICN, ECIC, EPIC, and EAC), prepared in accordance with the statutory accounting practices (SAP) of the National Association of Insurance Commissioners (NAIC) as well as SAP permitted by the states of California, Florida, and Nevada, were as follows: December 31, 2016 2015 (in millions) Capital stock and unassigned surplus $ 622.0 $ 498.8 Paid in capital 174.9 174.9 Surplus notes 32.0 32.0 Total statutory surplus $ 828.9 $ 705.7 Net income for the Company's insurance subsidiaries prepared in accordance with SAP for the years ended December 31, 2016 , 2015 and 2014 was $101.4 million , $87.8 million and $58.6 million , respectively. Treatment of the LPT Agreement, deferred policy acquisition costs, fair value of financial instruments, and the surplus notes (see Notes 5 , 10 , and 11 ) are the primary differences in the SAP-basis capital stock and total surplus of the insurance subsidiaries of $828.9 million and $705.7 million , and the GAAP-basis equity of the Company of $840.6 million and $760.8 million as of December 31, 2016 and 2015 , respectively. Under SAP accounting, the retroactive reinsurance gain resulting from the LPT Agreement is recorded as a special component of surplus (special surplus funds) in the initial year of the contract, and not reported as unassigned surplus until the Company has recovered amounts in excess of the original consideration paid. The special surplus funds are also reduced by the amount of extraordinary dividends as approved by the Nevada Division of Insurance. Under SAP, the surplus notes are recorded as a separate component of surplus. Under SAP, changes to the estimated contingent profit commission under the LPT Agreement are reflected in commission expense in the period that the estimate is revised. Insurance Company Dividends and Regulatory Requirements and Restrictions The ability of EHI to pay dividends on the Company's common stock and to pay other expenses will be dependent to a significant extent upon the ability of the Nevada domiciled insurance company, EICN, the California domiciled insurance company, ECIC, and the Florida domiciled insurance companies, EPIC and EAC, to pay dividends to their immediate holding company, Employers Group, Inc. (EGI) and, in turn, the ability of EGI to pay dividends to EHI. The amount of dividends each of the Company's subsidiaries may pay to their immediate parent is limited by the laws of its respective state of domicile. On December 31, 2016, the legal structure of the Company's insurance subsidiaries changed such that all four of its insurance subsidiaries are now wholly owned by EGI (ECIC is no longer a wholly owned subsidiary of EICN and EAC is no longer a wholly owned subsidiary of EPIC). This change in legal structure allows each of the Company's insurance subsidiaries to pay dividends directly to EGI. Nevada law limits the payment of cash dividends by EICN to its parent by providing that payments cannot be made except from available and accumulated surplus, otherwise unrestricted (unassigned), and derived from realized net operating profits and realized and unrealized capital gains. A stock dividend may be paid out of any available surplus. A cash or stock dividend prohibited by these restrictions may only be declared and distributed as an extraordinary dividend upon the prior approval of the Nevada Commissioner of Insurance (Nevada Commissioner). EICN may not pay such an extraordinary dividend or make an extraordinary distribution until the Nevada Commissioner either approves or does not disapprove the payment within 30 days after receiving notice of its declaration. An extraordinary dividend or distribution is defined by statute to include any dividend or distribution of cash or property whose fair market value, together with that of other dividends or distributions made within the preceding 12 months, exceeds the lesser of: (a) 10% of EICN's statutory surplus as regards to policyholders at the next preceding December 31; or (b) EICN's statutory net income, not including realized capital gains, for the 12-month period ending at the next preceding December 31. As of December 31, 2016 , EICN had positive unassigned surplus of $152.1 million . During 2016 , EICN paid an extraordinary dividend in the form of the common stock of ECIC, valued at $358.3 million , to EGI as part of the internal restructuring of the Company's insurance subsidiaries. As a result of the payment of its extraordinary dividend, any dividends paid by EICN through December 31, 2017 will require prior approval by the Nevada Department of Insurance. Under Florida law, without regulatory approval, EPIC and EAC may pay dividends if they do not exceed the greater of: the lesser of 10% of surplus or net income, not including realized capital gains, plus a 2-year carry forward; 10% of surplus, with dividends payable limited to unassigned funds minus 25% of unrealized capital gains; or, the lesser of 10% of surplus or net investment income plus a 3-year carry forward with dividends payable limited to unassigned funds minus 25% of unrealized capital gains. During 2016 , EPIC paid an extraordinary dividend in the form of the common stock of EAC, valued at $179.8 million , to EGI as part of the internal restructuring of the Company's insurance subsidiaries. As a result of the payment of its extraordinary dividend, any dividends paid by EPIC through in 2017 will require approval by the Florida Office of Insurance Regulation (FOIR). Additionally, EAC paid an extraordinary dividend in the amount of $32.2 million to EPIC. As a result of the payment of its extraordinary dividend, EAC can pay $18.0 million of dividends without prior regulatory approval beginning July 6, 2017. ECIC is subject to regulation by the California Department of Insurance (California DOI). The ability of ECIC to pay dividends was further limited by restrictions imposed by the California DOI in its approval of the Company's October 1, 2008 reinsurance pooling agreement. Under that approval: (a) ECIC must initiate discussions of its business plan with the California DOI if its net written premium to policyholder surplus ratio exceeds 1.5 to 1 ; (b) ECIC will not exceed a ratio of net written premium to policyholder surplus of 2 to 1 without approval of the California DOI; (c) if at any time ECIC's policyholder surplus decreases to 80% or less than the September 30, 2008 balance, ECIC shall cease issuing new policies in California, but may continue to renew existing policies until it has (i) received a capital infusion to bring its surplus position to the same level as that as of September 30, 2008 and (ii) submitted a new business plan to the California DOI; (d) ECIC will maintain a risk based capital (RBC) level of at least 350% of the authorized control level; (e) should ECIC fail to comply with any commitments listed herein, ECIC will consent to any request by the California DOI to cease issuing new policies in California, but may continue to renew existing policies until such time that as ECIC is able to achieve full compliance with each commitment; and (f) the obligations listed shall only terminate with the written consent of the California DOI. During the years ended December 31, 2016 , 2015 , and 2014 , ECIC was in compliance with these requirements. Additionally, the California Insurance Holding Company System Regulatory Act limits the ability of ECIC to pay dividends to its parent. California law provides that, absent prior approval of the California Insurance Commissioner, dividends may only be declared from earned surplus. For purpose of this statute, earned surplus excludes amounts (1) derived from net appreciation in the value of assets not yet realized, or (2) derived from an exchange of assets, unless the assets received are currently realizable in cash. In addition, California law provides that the appropriate insurance regulatory authorities in the state of California must approve (or, within a 30 day notice period, not disapprove) any dividend that, together with all other such dividends paid during the preceding 12 months, exceeds the greater of: (a) 10% of the paying company's statutory surplus as regards to policyholders at the preceding December 31; or (b) 100% of net income for the preceding year. During 2016 , ECIC paid an ordinary dividend in the amount of $33.5 million to EICN. ECIC can pay $4.6 million of dividends through June 21, 2017 and $38.1 million thereafter without prior regulatory approval, provided that no dividends are paid prior to June 21, 2017. EPIC and EAC are subject to regulation by the Florida Department of Financial Services (FDFS). Florida statute Section 624.408 requires EPIC and EAC to maintain minimum capital and surplus of the greater of $4.0 million or 10% of total liabilities. Florida statute Section 624.4095 requires EPIC and EAC to maintain a ratio of written premiums, defined as 1.25 times written premiums, to surplus of no greater than 10-to-1 for gross written premiums and 4-to-1 for net written premiums. During the years ended December 31, 2016 , 2015 , and 2014 , EPIC and EAC were in compliance with these statutes. Additionally, EICN, ECIC, EPIC, and EAC are required to comply with NAIC RBC requirements. RBC is a method of measuring the amount of capital appropriate for an insurance company to support its overall business operations in light of its size and risk profile. NAIC RBC standards are used by regulators to determine appropriate regulatory actions relating to insurers that show signs of weak or deteriorating conditions. As of December 31, 2016 , 2015 , and 2014 , EICN, ECIC, EPIC, and EAC each had total adjusted capital above all regulatory action levels.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income, Net	12 Months Ended
	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income, Net	Accumulated Other Comprehensive Income Accumulated other comprehensive income is comprised of unrealized gains on investments classified as available-for-sale, net of deferred tax expense. The following table summarizes the components of accumulated other comprehensive income: Years Ended December 31, 2016 2015 (in millions) Net unrealized gain on investments, before taxes $ 114.6 $ 128.6 Deferred tax expense on net unrealized gains (40.1 ) (45.0 ) Total accumulated other comprehensive income $ 74.5 $ 83.6

Employee Benefit and Retirement

Employee Benefit and Retirement Plans	12 Months Ended
	Dec. 31, 2016
Employee Benefit and Retirement Plans [Abstract]
Compensation and Employee Benefit Plans	Employee Benefit and Retirement Plans The Company maintains a 401(k) defined contribution plan covering all eligible Company employees (the Employers 401(k) Plan). Under the Employers 401(k) Plan, the Company's safe harbor matching consists of 100% matching contribution on salary deferrals up to 3% of compensation and then 50% matching contribution on salary deferrals from 3% to 5% of compensation. The Company's matching contribution to the Employers 401(k) Plan was $1.9 million , $1.8 million , and $1.7 million for the years ended December 31, 2016 , 2015 , and 2014 , respectively.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Common Share Basic earnings per share, which includes no dilution from outstanding stock-based awards, is computed by dividing net income by the weighted average number of common shares outstanding for the period. Diluted earnings per share reflect the potential dilutive impact of all outstanding stock-based awards on earnings per share. Diluted earnings per share includes common shares assumed issued under the “treasury stock method,” which reflects the potential dilution that would occur if outstanding RSUs and PSUs vested, and stock options were to be exercised. The following table presents the net income and the weighted average shares outstanding used in the earnings per share common share calculations. Years Ended December 31, 2016 2015 2014 (in millions, except share data) Net income $ 106.7 $ 94.4 $ 100.7 Weighted average number of shares outstanding–basic 32,434,580 32,070,911 31,529,621 Effect of dilutive securities: Stock options 246,562 286,764 223,811 PSUs 222,594 155,768 264,511 RSUs 73,099 48,010 51,126 Dilutive potential shares 542,255 490,542 539,448 Weighted average number of shares outstanding–diluted 32,976,835 32,561,453 32,069,069 Diluted earnings per share excludes those outstanding stock options and any other common stock equivalents in periods where the inclusion of such stock options and common stock equivalents would be anti-dilutive. The following table presents the number of stock options, PSUs and RSUs that were excluded from the Company's calculation of diluted earnings per share. Years Ended December 31, 2016 2015 2014 Stock options excluded as the exercise price was greater than the average market price — 20,200 173,247 Stock options, PSUs and RSUs excluded under the treasury method, as the potential proceeds on settlement or exercise was greater than the value of shares acquired 89,221 257,405 260,171

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2016
Selecled Quarterly Financial Data (Unaudited) [Abstract]
Quarterly Financial Information	Selected Quarterly Financial Data (Unaudited) Quarterly results for the years ended December 31, 2016 and 2015 were as follows: 2016 Quarters Ended March 31 June 30 September 30 December 31 (in millions, except per share data) Net premiums earned $ 172.6 $ 176.9 $ 173.3 $ 172.0 Net realized gains on investments 1.5 6.0 1.6 2.1 Losses and loss adjustment expenses 107.3 111.7 109.0 89.9 Commission expense 20.3 21.9 21.3 20.0 Underwriting and other operating expenses 36.3 33.6 31.7 34.5 Income tax expense 5.9 7.4 7.8 12.9 Net income 21.8 26.8 22.6 35.5 Earnings per common share: Basic 0.67 0.82 0.70 1.10 Diluted 0.66 0.81 0.69 1.08 2015 Quarters Ended March 31 June 30 September 30 December 31 (in millions, except per share data) Net premiums earned $ 159.0 $ 170.6 $ 179.0 $ 181.8 Net realized gains (losses) on investments 1.2 1.9 2.0 (15.8 ) Losses and loss adjustment expenses 106.2 101.5 115.8 105.9 Commission expense 18.7 22.9 21.0 22.8 Underwriting and other operating expenses 33.5 32.5 31.6 37.6 Income tax expense (benefit) 4.1 4.1 5.9 (9.1 ) Net income 14.0 29.2 24.5 26.7 Earnings per common share: Basic 0.44 0.91 0.76 0.83 Diluted 0.43 0.90 0.75 0.82 Significant Quarterly Adjustments The second quarter of 2016 was impacted by an increase in net realized gains on investments, which resulted from sales of equity securities, which were undertaken in order to meet certain cash needs at the holding company. The fourth quarter of 2016 was impacted by favorable prior accident year loss development of $16.9 million . The fourth quarter of 2015 was impacted by: (1) favorable prior accident year loss development of $8.5 million ; (2) a $36.9 million reallocation of loss reserves from non-taxable periods prior to January 1, 2000 to taxable years, which reduced the Company's income tax provision by $11.5 million ; and (3) other-than-temporary impairments of certain equity securities, which resulted in a $17.0 million net realized loss on investments, primarily due to a sustained downturn in the energy sector.

Schedule II. Condensed Financia

Schedule II. Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2016
Notes to Condensed Financial Statments [Abstract]
Schedule II. Condensed Financial Information of Registrant	Employers Holdings, Inc. Condensed Balance Sheets December 31, (in millions, except share data) 2016 2015 Assets Investments: Investment in subsidiaries $ 757.5 $ 647.1 Investment in fixed maturity securities at fair value (amortized cost $14.7 in 2016 and $40.2 in 2015) 16.0 42.2 Equity securities at fair value (amortized cost $46.0 in 2015) — 51.6 Total investments 773.5 740.9 Cash and cash equivalents 41.4 1.4 Accrued investment income 0.3 — Intercompany receivable — 0.2 Federal income taxes receivable 9.6 1.7 Deferred income taxes, net 20.0 20.6 Other assets 0.7 1.5 Total assets $ 845.5 $ 766.3 Liabilities and stockholders' equity Accounts payable and accrued expenses $ 4.8 $ 5.2 Intercompany payable 0.1 — Other liabilities — 0.3 Total liabilities 4.9 5.5 Stockholders' equity : Common stock, $0.01 par value; 150,000,000 shares authorized 56,226,277 and 55,589,454 shares issued and 32,128,922 and 32,216,480 shares outstanding at December 31, 2016 and 2015, respectively 0.6 0.6 Preferred stock, $0.01 par value; 25,000,000 shares authorized; none issued — — Additional paid-in capital 372.0 357.2 Retained earnings 777.2 682.0 Accumulated other comprehensive income, net of tax 74.5 83.6 Treasury stock, at cost (24,097,355 shares at December 31, 2016 and 23,372,974 shares at December 31, 2015) (383.7 ) (362.6 ) Total stockholders' equity 840.6 760.8 Total liabilities and stockholders' equity $ 845.5 $ 766.3 Employers Holdings, Inc. Condensed Statements of Income Years Ended December 31, 2016 2015 2014 (in millions, except per share data) Revenues Net investment income $ 1.9 $ 4.0 $ 5.2 Net realized gains on investments 8.0 2.4 5.8 Total revenues 9.9 6.4 11.0 Expenses Other operating expenses 13.8 13.8 13.5 Interest expense — 1.1 1.4 Total expenses 13.8 14.9 14.9 Loss before income taxes and equity in earnings of subsidiary (3.9 ) (8.5 ) (3.9 ) Income tax benefit (3.5 ) (3.3 ) (2.6 ) Net loss before equity in earnings of subsidiary (0.4 ) (5.2 ) (1.3 ) Equity in net income of subsidiary 107.1 99.6 102.0 Net income $ 106.7 $ 94.4 $ 100.7 Earnings per common share (Note 18): Basic $ 3.29 $ 2.94 $ 3.19 Diluted $ 3.24 $ 2.90 $ 3.14 Cash dividends declared per common share $ 0.36 $ 0.24 $ 0.24 Employers Holdings, Inc. Condensed Statement of Cash Flows Years Ended December 31, 2016 2015 2014 (in millions) Operating activities Net income $ 106.7 $ 94.4 $ 100.7 Adjustments to reconcile net income to net cash provided by (used in) operating activities: Equity in undistributed net income of subsidiary (107.1 ) (99.6 ) (102.0 ) Realized gains on investments (8.0 ) (2.4 ) (5.8 ) Stock-based compensation 5.8 4.6 6.0 Excess tax benefits from stock-based compensation — (1.2 ) (1.2 ) Amortization of premium on investments, net 0.4 0.9 1.0 Deferred income tax expense (benefit) 2.9 (4.6 ) (2.3 ) Change in operating assets and liabilities: Accounts payable, accrued expenses, and other liabilities (0.7 ) 1.7 1.2 Federal income taxes (7.9 ) 4.9 0.8 Other assets 0.8 0.4 0.9 Intercompany payable/receivable 0.3 0.1 (1.4 ) Other (0.4 ) 1.2 0.9 Net cash (used in) provided by operating activities (7.2 ) 0.4 (1.2 ) Investing activities Purchase of fixed maturity securities (31.0 ) (21.6 ) (12.0 ) Purchase of equity securities (3.6 ) (19.0 ) (20.7 ) Proceeds from sale of fixed maturity securities — 18.3 4.1 Proceeds from maturities and redemptions of investments 24.9 45.5 32.6 Proceeds from sale of equity securities 88.5 24.0 20.6 Capital contributions to subsidiary (8.0 ) — — Change in restricted cash equivalents — 4.6 (4.1 ) Net cash provided by investing activities 70.8 51.8 20.5 Financing activities Acquisition of common stock (21.1 ) — — Cash transactions related to stock-based compensation 9.0 4.8 1.6 Dividends paid to stockholders (11.5 ) (7.7 ) (7.6 ) Payments on notes payable — (60.0 ) (10.0 ) Excess tax benefits from stock-based compensation — 1.2 1.2 Net cash used in financing activities (23.6 ) (61.7 ) (14.8 ) Net increase (decrease) in cash and cash equivalents 40.0 (9.5 ) 4.5 Cash and cash equivalents at the beginning of the period 1.4 10.9 6.4 Cash and cash equivalents at the end of the period $ 41.4 $ 1.4 $ 10.9

Schedule VI. Supplemental Infor

Schedule VI. Supplemental Information	12 Months Ended
	Dec. 31, 2016
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
Schedule of Supplemental Information for Property, Casualty Insurance Underwriters	Schedule VI. Supplemental Information Concerning Property - Casualty Insurance Operations Employers Holdings, Inc. and Subsidiaries Consolidated Supplemental Information Concerning Property and Casualty Insurance Operations Year Ended Deferred Policy Acquisition Costs Reserves For Unpaid Losses And LAE Unearned Premiums Net Premiums Earned Net Investment Income Losses and LAE Related to Current Years Losses and LAE Related to Prior Years (including LPT Amortization and Adj) Amortization of Deferred Policy Acquisition Costs Paid Losses And LAE (including LPT Amortization and Adj) Net Premiums Written (in millions) 2016 $ 44.3 $ 2,301.0 $ 310.3 $ 694.8 $ 73.2 $ 452.9 $ (35.0 ) $ 104.5 $ 416.2 $ 694.6 2015 44.3 2,347.5 308.9 690.4 72.2 456.9 (27.6 ) 103.9 410.2 689.3 2014 44.6 2,369.7 310.8 684.5 72.4 503.8 (50.4 ) 102.7 340.6 687.6

Summary of Significant Accoun30

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies [Abstract]
Cash and Cash Equivalents, Policy	Cash and Cash Equivalents The Company considers all liquid investments with maturities of less than three months, as measured from the date of purchase, to be cash equivalents.
Restricted Cash and Cash Equivalents, Policy	Restricted Cash and Cash Equivalents Restricted cash and cash equivalents represent cash and cash equivalents held in trust in order to secure certain of the Company's obligations and, accordingly, are restricted as to withdrawal or usage. As of December 31, 2016 and 2015 the Company held $27.2 million and $32.7 million , respectively, in trust for reinsurance obligations, of which $3.6 million and $2.5 million , respectively, represented restricted cash and cash equivalents.
Investments, Policy	Short-Term Investments The Company considers all liquid investments with maturities of between three and twelve months, as measured from the date of purchase, to be short-term investments. Investment Securities The Company's investments in fixed maturity securities and equity securities are classified as available-for-sale and are reported at fair value with unrealized gains and losses excluded from earnings and reported as a separate component of stockholders' equity, net of deferred taxes, in accumulated other comprehensive income on the Company’s Consolidated Balance Sheets. Investment income consists primarily of interest and dividends generated by investment securities. Interest is recorded as earned on an accrual basis and dividends are recorded as earned at the ex-dividend date. Interest income on mortgage-backed and asset-backed securities is determined using the effective-yield method based on estimated principal repayments. Mortgage-backed securities are adjusted for the effects of changes in prepayment assumptions on the related accretion of discount or amortization of premium of such securities using the retrospective method. Realized gains and losses on investments are determined on a specific-identification basis. When, in the opinion of management, a decline in the fair value of an equity security below its cost is considered to be “other-than-temporary,” the equity security's cost is written down to its fair value at the time the other-than-temporary decline is identified. The determination of an other-than-temporary decline for fixed maturity securities includes, in addition to other relevant factors, a presumption that if the market value is below cost by a significant amount for a period of time, a bifurcation of the write-down may be necessary based on the portion of the loss that is deemed to be a “credit loss”, which is considered a realized loss, and the portion that is deemed to be an “other than credit loss”, which is considered to be an unrealized loss. If management has the intent to sell the fixed maturity security or more likely than not will be required to sell the fixed maturity security before its anticipated recovery, the investment is written down to its fair value and the entire impairment is recorded as a realized loss in the Company's Consolidated Statements of Comprehensive Income. If management does not have the intent to sell or will not be required to sell the fixed maturity security but does not expect to recover the amortized cost basis of the fixed maturity security, the amount of the other-than-temporary impairment is bifurcated (see Note 6 ).
Revenue Recognition, Policy	Revenue Recognition Premiums written are recognized as revenues, net of any applicable underlying reinsurance coverage, and are earned over the term of the related policy. At the end of the policy term, payroll-based premium audits are performed on substantially all policyholder accounts to determine the actual amount of net premiums earned for that policy year. Earned but unbilled premiums include estimated future audit premiums based on the Company's historical experience. These estimates are subject to changes in policyholders' payrolls, economic conditions, and seasonality, and are continually reviewed and adjusted as experience develops or new information becomes known. Any such adjustments are included in current operations; however, they are partially offset by the resulting changes in losses and LAE, commission expenses, and premium taxes. The Company's premiums receivable on its Consolidated Balance Sheets included $58.4 million and $53.5 million of additional premiums expected to be received from policyholders for final audits at December 31, 2016 and 2015 , respectively. The Company establishes a bad debt allowance on its premiums receivable through a charge included in underwriting and other operating expenses in its Consolidated Statements of Comprehensive Income. This bad debt allowance is determined based on estimates and assumptions to project future experience. After all collection efforts have been exhausted, the Company reduces the bad debt allowance for write-offs of premiums receivable that have been deemed uncollectible. The Company's bad debt allowance was $9.8 million and $12.2 million at December 31, 2016 and 2015 , respectively.
Deferred Policy Acquisition Costs, Policy	Deferred Policy Acquisition Costs Policy acquisition costs, those costs that relate directly to the successful acquisition of new or renewal insurance contracts, including underwriting, policy issuance and processing, medical and inspection, and sales force contract selling are deferred and amortized as the related premiums are earned. Amortization of deferred policy acquisition costs for the years ended December 31, 2016 , 2015 , and 2014 , was $104.5 million , $103.9 million , and $102.7 million , respectively. If the sum of a policy’s expected losses and LAE and deferred policy acquisition costs exceeds the related unearned premiums and projected investment income, a premium deficiency is determined to exist. In this event, deferred policy acquisition costs are immediately expensed to the extent necessary to eliminate the premium deficiency. If the premium deficiency exceeds deferred acquisition costs then a liability is accrued for the excess deficiency. There were no premium deficiency adjustments recognized during the years ended December 31, 2016 , 2015 and 2014 .
Unpaid Loss and LAE Reserves, Policy	Unpaid Loss and LAE Reserves Unpaid loss and LAE reserves represent management's best estimate of the ultimate net cost of all reported and unreported losses incurred for the applicable periods, less payments made. The estimated reserves for losses and LAE include the accumulation of estimates for all claims reported prior to the balance sheet date, estimates of claims incurred but not reported, and estimates of expenses for investigating and adjusting all incurred and unadjusted claims (based on projections of relevant historical data). Amounts reported are subject to the impact of future changes in economic, regulatory and social conditions. Management believes that, subject to the inherent variability in any such estimate, the reserves are within a reasonable and acceptable range of adequacy. Estimates for claims prior to the balance sheet date are continually monitored and reviewed, and as settlements are made or reserves adjusted, the differences are reported in current operations. Salvage and subrogation recoveries are estimated based on a review of the level of historical salvage and subrogation recoveries.
Reinsurance, Policy	Reinsurance In the ordinary course of business, the Company may purchase excess of loss reinsurance in order to protect it against the impact of large and/or catastrophic losses. Additionally, the Company is a party to the LPT Agreement (see Note 10 ). These reinsurance arrangements reduce the Company's exposure to such losses since its reinsurers are liable to the Company to the extent of the reinsurance protection provided. However, the Company remains liable for all losses it incurs to the extent that any reinsurer is unable or unwilling to make timely payments under its reinsurance agreements. Balances due from reinsurers on unpaid losses, including an estimate of such recoverables related to reserves for incurred but not reported losses, are reported as reinsurance recoverables on the Company’s Consolidated Balance Sheets. Reinsurance recoverables on paid losses represents amounts currently due from reinsurers. Reinsurance recoverables on unpaid losses represents amounts that will be collectible from reinsurers once the losses are paid. Reinsurance recoverables on unpaid losses and LAE amounted to $580.0 million and $628.2 million at December 31, 2016 and 2015 , respectively. Ceded reinsurance premiums are accounted for on a basis consistent with those used in accounting for the underlying premiums, and are reported as reductions to arrive at net premiums written and earned. Ceded losses and LAE are also accounted for on a basis consistent with those used in accounting for the original policies issued and the terms of the relevant reinsurance agreement, and are recorded as reductions to losses and LAE incurred. Pursuant to the LPT Agreement, loss expenses are deemed to be 7% of total losses paid and are payable to the Company as compensation for management of the claims under the LPT Agreement. The Deferred Gain is amortized using the recovery method, whereby the amortization is determined by the proportion of actual reinsurance recoveries to total estimated recoveries through the life of the LPT Agreement, and is recorded in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income. Any adjustment to the estimated loss and LAE reserves ceded under the LPT Agreement results in a cumulative adjustment to the Deferred Gain, which is also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, such that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement. Additionally, the Company is entitled to receive a contingent profit commission under the LPT Agreement. The contingent profit commission is equal to 30% of the favorable difference between actual paid losses and LAE and expected paid losses and LAE as established in the LPT Agreement based on losses paid through June 30, 2024. The contingent profit commission is paid every five years beginning June 30, 2004 for the first 25 years of the agreement. The Company could be required to return any previously received contingent profit commission, plus interest, in the event of unfavorable differences through June 30, 2024. The Company records an estimate of contingent profit commission in its Consolidated Balance Sheets as Contingent commission receivable–LPT Agreement and a corresponding liability is recorded as Deferred reinsurance gain–LPT Agreement. The Contingent commission receivable–LPT Agreement is reduced as amounts are received from participating reinsurers. The Deferred reinsurance gain–LPT Agreement is amortized using the recovery method. The amortization of the contingent profit commission is determined by the proportion of actual reinsurance recoveries to total estimated recoveries over the life of the contingent profit commission (through June 30, 2024), and is recorded in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income. Any adjustment to the contingent profit commission under the LPT Agreement results in a cumulative adjustment to the Deferred Gain, which is also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, such that the Deferred Gain reflects the balance that would have existed had the revised contingent profit commission been recognized at the inception of the LPT Agreement.
Property, and Equipment, Policy	Property and Equipment Property and equipment are stated at cost less accumulated depreciation (see Note 7 ). Expenditures for maintenance and repairs are charged against operations as incurred. Electronic data processing equipment, software, furniture and equipment, and automobiles are depreciated using the straight-line method over three to seven years . Leasehold improvements are carried at cost less accumulated amortization. The Company amortizes leasehold improvements using the straight-line method over the lesser of the useful life of the asset or the remaining original lease term, excluding options or renewal periods. Leasehold improvements are generally amortized over three to five years .
Obligations Held Under Capital Leases, Policy	Obligations Held Under Capital Leases Leased property and equipment meeting capital lease criteria are capitalized at the lower of the present value of the related lease payments or the fair value of the leased asset at the inception of the lease. Amortization is calculated using the straight-line method based on the term of the lease and is included in the depreciation expense of property and equipment. See Note 12 for additional disclosures related to capital leases.
Income Taxes, Policy	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the Company's financial statements. Under this method, the Company determines deferred tax assets and liabilities on the basis of the differences between the financial statement and tax bases of assets and liabilities by using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company records uncertain tax positions in accordance with ASC 740 on the basis of a two-step process. Recognition (Step 1) occurs when the Company concludes that a tax position, based solely on its technical merits, is more likely than not to be sustained upon examination. Measurement (Step 2) is addressed only if Step 1 has been satisfied. Under Step 2, the tax benefit is measured as the largest amount of benefit, determined on a cumulative probability basis, that is more likely than not to be realized upon ultimate settlement. The Company recognizes deferred tax assets when it determines that such assets are more likely than not to be realized in future periods. In making such a determination, the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If the Company determines that it would be able to realize its deferred tax assets in the future in excess of their net recorded amount, the Company would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.
Credit Risk, Policy	Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents (including restricted cash equivalents), short-term investments, investment securities, premiums receivable, and reinsurance recoverable balances. The Company’s cash equivalents and short-term investments include investments in money market securities and securities backed by the U.S. government. The Company's investment securities are diversified throughout many industries and geographic regions and include investments in U.S. government and U.S. government-sponsored enterprises. The Company believes that it has no significant concentrations of credit risk from a single issue or issuer within its cash equivalents, short-term investments and investment securities other than concentrations in U.S. government and U.S. government-sponsored enterprises. The Company's premiums receivable are generally diversified due to the large number of entities composing the Company's policyholder base and their dispersion across many different industries. The Company monitors the financial condition of its reinsurers to minimize its exposure to significant losses from reinsurer insolvencies. The Company also obtains collateral from its reinsurers in order to mitigate the risks related to insolvencies. At December 31, 2016 , $3.5 million of the Company's reinsurance recoverables were collateralized by cash or letters of credit and an additional $355.7 million was in trust accounts for reinsurance recoverables specifically related to the LPT Agreement.
Fair Value of Financial Instruments, Policy	Fair Value of Financial Instruments The fair values of the Company's financial instruments have been determined using available market information and other appropriate valuation methodologies. Judgment is required in developing fair value estimates where quoted market prices are not available. Accordingly, these estimates are not necessarily indicative of the amounts that could be realized in a current market exchange. The use of different market assumptions or estimating methodologies may have an effect on the estimated fair value amounts. The following methods and assumptions were used by the Company in estimating the fair value of its financial instruments: Cash and cash equivalents, short-term investments, premiums receivable, accounts payable, and accrued expenses and other liabilities. The carrying amounts for each of these financial instruments as reported in the Company's Consolidated Balance Sheets approximate their fair values. Investment Securities. The Company’s investment securities are predominantly valued on the basis of actual market transactions or observable inputs. A small portion of the Company’s investment securities are valued on the basis of pricing models with significant unobservable inputs or nonbinding broker quotes. See Note 5 .
Goodwill and Other Intangible Assets, Policy	Goodwill and Other Intangible Assets The Company tests for impairment of goodwill and non-amortizable intangible assets in the fourth quarter of each year. At the end of each quarter, management considers the results of the previous analysis as well as any recent developments that may constitute triggering events requiring the impairment analysis of goodwill and other intangible assets to be updated. The Company has assessed the effects of current economic conditions on the Company's financial condition and results of operations and changes in the Company's stock price and determined that there were no impairments of these assets as of December 31, 2016 and 2015 . Intangible assets related to state licenses are not subject to amortization. Intangibles related to insurance relationships are amortized in proportion to the expected period of benefit over the next two years . The gross carrying value, accumulated amortization, and net carrying value for the Company's intangible assets, by major class, as of December 31, were as follows: 2016 2015 Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value (in millions) State licenses $ 7.7 $ — $ 7.7 $ 7.7 $ — $ 7.7 Insurance relationships 9.4 $ (8.9 ) 0.5 9.4 $ (8.6 ) 0.8 Total $ 17.1 $ (8.9 ) $ 8.2 $ 17.1 $ (8.6 ) $ 8.5 During the years ended December 31, 2016 , 2015 , and 2014 , the Company recognized $0.3 million , $0.5 million , and $0.7 million in amortization expenses associated with its intangible assets, respectively. These amortization expenses are included in the Company's Consolidated Statements of Comprehensive Income in underwriting and other operating expenses. Future amortization expenses associated with the Company's intangible assets are expected to be as follows: Year Amount (in millions) 2017 0.3 2018 0.2 Total $ 0.5
Stock-based Compensation, Policy	Stock-Based Compensation The Company provides stock-based compensation to its directors and certain of its employees, which is recognized in its Consolidated Statements of Comprehensive Income based on estimated fair values over the relevant service period (see Note 14 ).

Changes in Estimates (Tables)

Changes in Estimates (Tables)	12 Months Ended
	Dec. 31, 2016
Changes in Estimates [Abstract]
Change to Contingent Profit Commission [Table Text Block]	The Company increased its estimate of Contingent commission receivable – LPT Agreement (LPT Contingent Commission Adjustments) in each of 2016 , 2015 , and 2014 as a result of the determination that adjustments were necessary to reflect observed favorable paid loss trends in each of those years. The following table shows the impact to the Consolidated Statements of Comprehensive Income related to these changes in estimates. 2016 2015 2014 (in millions, except per share data) Change in estimate of Contingent commission receivable - LPT Agreement $ 1.9 $ 2.8 $ 12.5 Cumulative adjustment to the Deferred Gain (1) (1.8 ) (2.6 ) (10.8 ) Net income impact from this change in estimate 1.8 2.6 10.8 Earnings per common share impact from this change in estimate Basic 0.06 0.08 0.34 Diluted 0.05 0.08 0.34 (1) The cumulative adjustments to the Deferred Gain were also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised loss and LAE reserves been recognized at the inception of the LPT Agreement.
Change Due to Estimated Reserves Ceded Under the LPT Agreement [Table Text Block]	The Company reduced its estimated loss and LAE reserves ceded under the LPT Agreement (LPT Reserve Adjustments) in each of the years 2016 , 2015 , and 2014 as a result of the determination that adjustments were necessary to reflect observed favorable paid loss trends in each of these years. The following table shows the financial statement impact related to the LPT Reserve Adjustments. 2016 2015 2014 (in millions, except per share data) LPT Reserve Adjustments $ (5.0 ) $ (10.0 ) $ (46.8 ) Cumulative adjustment to the Deferred Gain (1) (3.1 ) (6.4 ) (31.1 ) Net income impact from this change in estimate 3.1 6.4 31.1 Earnings per common share impact from this change in estimate Basic 0.10 0.20 0.99 Diluted 0.09 0.20 0.97 (1) The cumulative adjustments to the Deferred Gain were also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised loss and LAE reserves been recognized at the inception of the LPT Agreement.
Change in Reserves for Non-taxable Periods [Table Text Block]	The Company reallocated loss and LAE reserves from non-taxable periods prior to January 1, 2000 to taxable years, which reduced its effective tax rates, in each of 2015 and 2014 . These changes in estimates were the result of the determination that a reallocation of reserves among accident years was appropriate to address a continuation of observed loss trends in each of those years. The following table shows the financial statement impact of these changes in estimates. 2015 2014 (in millions, except per share data) Loss and LAE reserves reallocated to taxable years $ 56.3 $ 13.1 Impact to effective tax rate (15.4 )% (3.4 )% Net income impact from this change in estimate $ 15.3 $ 3.6 Earnings per common share impact from this change in estimate Basic 0.48 0.11 Diluted 0.47 0.11

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies [Abstract]
Schedule of intangible assets table	The gross carrying value, accumulated amortization, and net carrying value for the Company's intangible assets, by major class, as of December 31, were as follows: 2016 2015 Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value (in millions) State licenses $ 7.7 $ — $ 7.7 $ 7.7 $ — $ 7.7 Insurance relationships 9.4 $ (8.9 ) 0.5 9.4 $ (8.6 ) 0.8 Total $ 17.1 $ (8.9 ) $ 8.2 $ 17.1 $ (8.6 ) $ 8.5
Expected amortization expense table	Future amortization expenses associated with the Company's intangible assets are expected to be as follows: Year Amount (in millions) 2017 0.3 2018 0.2 Total $ 0.5

Fair Value of Financial Instr33

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value of Financial Instruments [Abstract]
Estimated fair value of financial instruments table	The carrying value and the estimated fair value of the Company's financial instruments as of December 31, were as follows: 2016 2015 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Financial assets (in millions) Investments (Note 6) $ 2,552.6 $ 2,552.6 $ 2,487.2 $ 2,487.2 Cash and cash equivalents 67.2 67.2 56.6 56.6 Restricted cash and cash equivalents 3.6 3.6 2.5 2.5 Financial liabilities Notes payable (Note 11) $ 32.0 $ 33.0 $ 32.0 $ 36.6
Fair value, assets and liabilities measured on recurring basis table	The following table presents the items in the Company's Consolidated Balance Sheets that are stated at fair value and the corresponding fair value measurements. December 31, 2016 December 31, 2015 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 (in millions) Fixed maturity securities U.S. Treasuries $ — $ 127.4 $ — $ — $ 120.2 $ — U.S. Agencies — 12.8 — — 24.4 — States and municipalities — 851.6 — — 854.5 — Corporate securities — 956.7 — — 925.3 — Residential mortgage-backed securities — 258.0 — — 237.9 — Commercial mortgage-backed securities — 95.5 — — 80.3 — Asset-backed securities — 35.4 7.0 — 45.9 — Total fixed maturity securities $ — $ 2,337.4 $ 7.0 $ — $ 2,288.5 $ — Equity securities Industrial and miscellaneous $ 167.2 $ — $ — $ 178.4 $ — $ — Non-redeemable preferred (FHLB stock) — — 4.9 — — — Other 20.1 — — 20.3 — — Total equity securities $ 187.3 $ — $ 4.9 $ 198.7 $ — $ — Short-term investments $ — $ 16.0 $ — $ — $ — $ —
Fair value, assets measured on recurring basis, unobservable input reconciliation table	The following table provides a reconciliation of the beginning and ending balances that are measured using Level 3 inputs for the year ended December 31, 2016 . Level 3 Securities (in millions) Beginning balance, January 1, 2016 $ — Purchases 11.9 Ending balance, December 31, 2016 $ 11.9
Schedule of Cash and Cash Equivalents [Table Text Block]	The following table presents cash equivalents at NAV and total cash and cash equivalents carried at fair value on the Company's Consolidated Balance Sheets. December 31, 2016 December 31, 2015 Cash and cash equivalents at fair value $ 9.7 $ 56.6 Cash equivalents measured at NAV, which approximates fair value 57.5 — Total cash and cash equivalents $ 67.2 $ 56.6

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Investments [Abstract]
Available-for-sale securities table	The cost or amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the Company’s investments were as follows: Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value At December 31, 2016 (in millions) Fixed maturity securities U.S. Treasuries $ 124.1 $ 3.5 $ (0.2 ) $ 127.4 U.S. Agencies 11.9 0.9 — 12.8 States and municipalities 833.0 24.7 (6.1 ) 851.6 Corporate securities 942.3 18.9 (4.5 ) 956.7 Residential mortgage-backed securities 255.9 4.7 (2.6 ) 258.0 Commercial mortgage-backed securities 96.1 0.4 (1.0 ) 95.5 Asset-backed securities 42.6 — (0.2 ) 42.4 Total fixed maturity securities 2,305.9 53.1 (14.6 ) 2,344.4 Equity securities Industrial and miscellaneous 100.5 67.4 (0.7 ) 167.2 Non-redeemable preferred (FHLB stock) 4.9 — — 4.9 Other 10.7 9.4 — 20.1 Total equity securities 116.1 76.8 (0.7 ) 192.2 Short-term investments 16.0 — — 16.0 Total investments $ 2,438.0 $ 129.9 $ (15.3 ) $ 2,552.6 At December 31, 2015 Fixed maturity securities U.S. Treasuries $ 116.4 $ 3.9 $ (0.1 ) $ 120.2 U.S. Agencies 23.0 1.4 — 24.4 States and municipalities 809.4 45.1 — 854.5 Corporate securities 913.4 19.9 (8.0 ) 925.3 Residential mortgage-backed securities 231.8 7.1 (1.0 ) 237.9 Commercial mortgage-backed securities 81.1 0.2 (1.0 ) 80.3 Asset-backed securities 46.0 — (0.1 ) 45.9 Total fixed maturity securities 2,221.1 77.6 (10.2 ) 2,288.5 Equity securities Industrial and miscellaneous 126.0 56.8 (4.4 ) 178.4 Other 11.5 9.0 (0.2 ) 20.3 Total equity securities 137.5 65.8 (4.6 ) 198.7 Total investments $ 2,358.6 $ 143.4 $ (14.8 ) $ 2,487.2
Investments classified by contractual maturity date table	The amortized cost and estimated fair value of the Company's fixed maturity securities at December 31, 2016 , by contractual maturity, are shown below. Expected maturities differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Amortized Cost Estimated Fair Value (in millions) Due in one year or less $ 136.1 $ 137.4 Due after one year through five years 896.8 918.6 Due after five years through ten years 613.4 625.7 Due after ten years 265.0 266.8 Mortgage and asset-backed securities 394.6 395.9 Total $ 2,305.9 $ 2,344.4
Unrealized loss on investments table	The following is a summary of investments that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 months or greater as of December 31, 2016 and 2015 . December 31, 2016 December 31, 2015 Estimated Fair Value Gross Unrealized Losses Number of Issues Estimated Fair Value Gross Unrealized Losses Number of Issues Less than 12 months: (dollars in millions) Fixed maturity securities U.S. Treasuries $ 33.3 $ (0.2 ) 14 $ 27.4 $ (0.1 ) 20 States and municipalities 200.9 (6.1 ) 50 — — — Corporate securities 289.5 (4.1 ) 101 328.4 (4.7 ) 122 Residential mortgage-backed securities 137.5 (2.6 ) 51 50.5 (0.8 ) 24 Commercial mortgage-backed securities 48.0 (1.0 ) 21 51.5 (1.0 ) 22 Asset-backed securities 30.1 (0.2 ) 20 34.1 — 27 Total fixed maturity securities 739.3 (14.2 ) 257 491.9 (6.6 ) 215 Equity securities 13.6 (0.6 ) 28 35.8 (4.6 ) 45 Total less than 12 months $ 752.9 $ (14.8 ) 285 $ 527.7 $ (11.2 ) 260 12 months or greater: Fixed maturity securities Corporate securities $ 15.2 $ (0.4 ) 5 $ 34.6 $ (3.3 ) 15 Residential mortgage-backed securities — — — 7.1 (0.2 ) 25 Asset-backed securities — — — 11.1 (0.1 ) 4 Total fixed maturity securities 15.2 (0.4 ) 5 52.8 (3.6 ) 44 Equity securities 1.7 (0.1 ) 5 — — — 12 months or greater $ 16.9 $ (0.5 ) 10 $ 52.8 $ (3.6 ) 44 Total available-for-sale: Fixed maturity securities U.S. Treasuries $ 33.3 $ (0.2 ) 14 $ 27.4 $ (0.1 ) 20 States and municipalities 200.9 (6.1 ) 50 — — — Corporate securities 304.7 (4.5 ) 106 363.0 (8.0 ) 137 Residential mortgage-backed securities 137.5 (2.6 ) 51 57.6 (1.0 ) 49 Commercial mortgage-backed securities 48.0 (1.0 ) 21 51.5 (1.0 ) 22 Asset-backed securities 30.1 (0.2 ) 20 45.2 (0.1 ) 31 Total fixed maturity securities 754.5 (14.6 ) 262 544.7 (10.2 ) 259 Equity securities 15.3 (0.7 ) 33 35.8 (4.6 ) 45 Total available-for-sale $ 769.8 $ (15.3 ) 295 $ 580.5 $ (14.8 ) 304
Net realized gains and change in unrealized gains (losses), available for sale securities table	Net realized gains on investments and the change in unrealized gains (losses) on fixed maturity and equity securities are determined on a specific-identification basis and were as follows: Years Ended December 31, 2016 2015 2014 Net realized gains (losses) on investments (in millions) Fixed maturity securities Gross gains $ 1.9 $ 0.5 $ 1.1 Gross losses (0.7 ) (0.4 ) — Net realized gains on fixed maturity securities $ 1.2 $ 0.1 $ 1.1 Equity securities Gross gains $ 16.6 $ 8.1 $ 15.7 Gross losses (6.6 ) (18.9 ) (0.5 ) Net realized gains (losses) on equity securities $ 10.0 $ (10.8 ) $ 15.2 Total $ 11.2 $ (10.7 ) $ 16.3 Change in unrealized gains (losses) Fixed maturity securities $ (28.9 ) $ (22.2 ) $ 23.1 Equity securities 14.9 (13.7 ) 2.2 Total $ (14.0 ) $ (35.9 ) $ 25.3
Investment income table	Net investment income was as follows: Years Ended December 31, 2016 2015 2014 (in millions) Fixed maturity securities $ 68.5 $ 68.8 $ 70.7 Equity securities 7.4 5.9 4.2 Cash equivalents and restricted cash 0.4 0.1 0.1 Gross investment income 76.3 74.8 75.0 Investment expenses (3.1 ) (2.6 ) (2.6 ) Net investment income $ 73.2 $ 72.2 $ 72.4

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property and Equipment [Abstract]
Property, plant and equipment table	Property and equipment consists of the following: As of December 31, 2016 2015 (in millions) Furniture and equipment $ 2.3 $ 2.3 Leasehold improvements 4.3 4.3 Computers and software 59.0 56.7 Automobiles 1.2 1.2 Property and equipment, gross 66.8 64.5 Accumulated amortization and depreciation (44.6 ) (39.6 ) Property and equipment, net $ 22.2 $ 24.9

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Taxes [Abstract]
Summary of income tax contingencies table	The Company's provision for income taxes consisted of the following: Years Ended December 31, 2016 2015 2014 Current tax expense: (in millions) Federal $ 20.3 $ 9.5 $ 6.3 State 0.3 1.1 0.1 Total current tax expense 20.6 10.6 6.4 Deferred federal tax expense (benefit) 13.4 (5.6 ) (0.5 ) Income tax expense $ 34.0 $ 5.0 $ 5.9
Reconciliation of federal staturoty income tax rates to the effective tax rates table	The difference between the statutory federal tax rate of 35% and the Company's effective tax rate on net income before income taxes as reflected in the Consolidated Statements of Comprehensive Income was as follows: Years Ended December 31, 2016 2015 2014 (in millions) Expense computed at statutory rate $ 49.3 $ 34.8 $ 37.3 Tax-advantaged investment income (8.5 ) (8.6 ) (8.8 ) Pre-Privatization reserve adjustments, excluding LPT — (15.3 ) (3.6 ) LPT deferred gain amortization (4.7 ) (4.9 ) (8.4 ) LPT Reserve Adjustment (1.1 ) (2.2 ) (10.9 ) Other (1.0 ) 1.2 0.3 Income tax expense $ 34.0 $ 5.0 $ 5.9
Deferred tax assets and liabilities	The significant components of deferred income taxes, net, were as follows as of December 31: 2016 2015 Deferred Tax Deferred Tax Assets Liabilities Assets Liabilities (in millions) Unrealized capital gains, net $ — $ 40.1 $ — $ 45.0 Deferred policy acquisition costs — 15.7 — 15.7 Intangible assets — 2.9 — 3.0 Loss reserve discounting for tax reporting 51.7 — 56.3 — Unearned premiums 20.9 — 20.9 — Allowance for bad debt 3.4 — 4.3 — Stock-based compensation 4.4 — 4.1 — Accrued liabilities 8.1 — 8.4 — Minimum tax credit 27.8 — 28.0 — Net operating loss carryforward — — 8.7 — Other 9.7 7.9 8.4 7.5 Total $ 126.0 $ 66.6 $ 139.1 $ 71.2 Deferred income taxes, net $ 59.4 $ 67.9

Liability for Unpaid Losses a37

Liability for Unpaid Losses and Loss Adjustment Expenses (Tables)	12 Months Ended
	Dec. 31, 2016
Liability for Unpaid Losses and Loss Adjustment Expenses [Abstract]
Changes in the liability for unpaid losses and LAE table	The following table represents a reconciliation of changes in the liability for unpaid losses and LAE. Years Ended December 31, 2016 2015 2014 (in millions) Unpaid losses and LAE at beginning of period $ 2,347.5 $ 2,369.7 $ 2,330.5 Less reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE 628.2 669.5 743.1 Net unpaid losses and LAE at beginning of period 1,719.3 1,700.2 1,587.4 Losses and LAE, net of reinsurance, incurred in: Current year 452.9 456.9 503.8 Prior years (18.4 ) (7.2 ) 4.6 Total net losses and LAE incurred during the period 434.5 449.7 508.4 Paid losses and LAE, net of reinsurance, related to: Current year 78.7 75.4 75.9 Prior years 354.1 355.2 319.7 Total net paid losses and LAE during the period 432.8 430.6 395.6 Ending unpaid losses and LAE, net of reinsurance 1,721.0 1,719.3 1,700.2 Reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE 580.0 628.2 669.5 Unpaid losses and LAE at end of period $ 2,301.0 $ 2,347.5 $ 2,369.7
Short-duration Insurance Contracts, Claims Development [Table Text Block]	The Company analyzed the usefulness of disaggregation of its results and determined the characteristics associated with the policies and the related unpaid loss reserves, incurred losses, and payment patterns are similar in nature. As such, the following tables show the Company's historical incurred and cumulative paid losses and LAE development, net of reinsurance, as well as IBNR loss reserves and the number of reported claims on an aggregated basis as of December 31, 2016 for each of the previous 10 accident years. Incurred Losses and LAE, Net of Reinsurance Years Ended December 31, As of December 31, 2016 Accident Year 2007 (1) 2008 (1) 2009 (1) 2010 (1) 2011 (1) 2012 (1) 2013 (1) 2014 (1) 2015 (1) 2016 IBNR Cumulative number of reported claims (in millions, except claims counts) 2007 $ 349.4 $ 341.8 $ 340.1 $ 340.3 $ 332.9 $ 332.7 $ 334.7 $ 334.6 $ 339.2 $ 346.6 $ 15.1 31,326 2008 315.9 315.3 317.8 329.2 329.5 335.1 336.9 343.8 341.4 16.2 28,082 2009 255.4 266.9 279.0 280.1 283.6 283.7 291.2 290.5 16.3 22,666 2010 204.9 224.4 228.1 246.1 250.2 262.0 259.9 23.8 18,533 2011 253.7 267.3 272.0 277.4 296.3 292.6 34.0 19,553 2012 348.8 359.9 360.9 386.4 388.2 60.5 25,930 2013 452.6 460.6 478.6 472.6 90.1 28,740 2014 463.4 445.8 432.9 107.4 28,231 2015 422.2 425.8 135.6 26,560 2016 419.0 226.1 21,239 Total $ 3,669.6 Cumulative Paid Losses and LAE, Net of Reinsurance Years Ended December 31, Accident Year 2007 (1) 2008 (1) 2009 (1) 2010 (1) 2011 (1) 2012 (1) 2013 (1) 2014 (1) 2015 (1) 2016 (in millions) 2007 $ 74.2 $ 165.3 $ 208.9 $ 236.7 $ 256.2 $ 270.0 $ 280.2 $ 288.3 $ 297.2 $ 302.3 2008 71.1 155.4 201.8 234.7 255.3 271.1 284.2 293.6 300.7 2009 59.0 130.6 174.1 202.0 219.3 232.1 242.3 249.5 2010 47.1 105.6 143.8 171.7 190.7 206.2 215.4 2011 47.4 115.1 162.6 193.8 217.5 230.1 2012 58.6 148.3 214.2 261.4 289.9 2013 68.5 184.4 263.8 317.4 2014 65.3 172.7 248.9 2015 65.5 174.5 2016 65.6 Total $ 2,394.2 All outstanding liabilities for unpaid losses and LAE prior to 2007, net of reinsurance 346.2 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 1,621.6 (1) Data presented for these calendar years is required supplementary information, which is unaudited
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Table Text Block]	The following table represents a reconciliation of claims development to the aggregate carrying amount of the liability for unpaid losses and LAE: December 31, 2016 (in millions) Liabilities for unpaid losses and LAE, net of reinsurance $ 1,621.6 Reinsurance recoverable on unpaid losses 580.0 Unallocated LAE 99.4 Total liability for unpaid losses and LAE $ 2,301.0
Short-duration Insurance Contracts, Schedule of Historical Claims Duration [Table Text Block]	The following table presents the average annual percentage payout of incurred claims by age, net of reinsurance, as of December 31, 2016 and is presented as required supplementary information, which is unaudited: Average Annual Percentage Payout of Claims by Age, Net of Reinsurance Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 17.3 % 24.4 % 15.4 % 10.3 % 6.7 % 4.7 % 3.5 % 2.5 % 2.3 % 1.5 %

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2016
Reinsurance [Abstract]
Supplemental schedule of reinsurance premiums for insurance companies table	The effects of reinsurance on the Company's written and earned premiums and on its losses and LAE incurred were as follows: Years Ended December 31, 2016 2015 2014 Written Earned Written Earned Written Earned (in millions) Direct premiums $ 691.0 $ 691.0 $ 684.9 $ 686.0 $ 686.8 $ 684.3 Assumed premiums 10.4 10.6 12.8 12.8 10.9 10.3 Gross premiums 701.4 701.6 697.7 698.8 697.7 694.6 Ceded premiums (6.8 ) (6.8 ) (8.4 ) (8.4 ) (10.1 ) (10.1 ) Net premiums $ 694.6 $ 694.8 $ 689.3 $ 690.4 $ 687.6 $ 684.5 Ceded losses and LAE incurred $ 0.1 $ 10.1 $ 17.2 Ceded losses and LAE incurred includes the amortization of the Deferred Gain, LPT Reserve Adjustments, and LPT Contingent Commission Adjustments.

Notes Payable (Tables)

Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2016
Notes Payable [Abstract]
Schedule of long-term debt instruments table	Notes payable is comprised of the following: December 31, 2016 2015 (in millions) Dekania Surplus Note, due April 30, 2034 $ 10.0 $ 10.0 ICONS Surplus Note, due May 26, 2034 12.0 12.0 Alesco Surplus Note, due December 15, 2034 10.0 10.0 Balance $ 32.0 $ 32.0
Schedule of maturities of long-term debt table	Principal payment obligations on notes payable outstanding at December 31, 2016 , were as follows: Year Principal Due (in millions) 2017 - 2021 $ — Thereafter 32.0 Total $ 32.0

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies [Abstract]
Operating and capital leases schedule of future minimum lease payments table	The future lease payments for the next five years on these non-cancelable operating and capital leases at December 31, 2016 , were as follows: Year Operating Leases Capital Leases (in millions) 2017 $ 5.1 $ 0.3 2018 3.7 0.2 2019 3.1 0.1 2020 2.5 0.1 2021 1.1 0.1 Thereafter 0.1 — Total $ 15.6 $ 0.8
Schedule of capital leased asssets table	Property held under capital leases is included in property and equipment as follows: Asset Class 2016 2015 (in millions) Computers and software $ — $ 0.4 Automobiles 1.2 1.2 1.2 1.6 Accumulated amortization (0.6 ) (1.0 ) Total $ 0.6 $ 0.6

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Stock-Based Compensation [Abstract]
Schedule of compensation cost for share-based payment arrangements, allocation of share-based compensation costs by plan table	Net stock-based compensation expense recognized in the Company's Consolidated Statements of Comprehensive Income was as follows: Years Ended December 31, 2016 2015 2014 Stock-based compensation expense related to: (in millions) Stock options $ 0.7 $ 1.0 $ 1.2 RSUs 1.9 2.0 1.9 PSUs 3.2 1.6 2.9 Total 5.8 4.6 6.0 Less: related tax benefit 2.0 1.6 2.1 Net stock-based compensation expense $ 3.8 $ 3.0 $ 3.9
Schedule of share-based payment award, stock options, valuation assumptions table	The fair value of the stock options granted during the years ended December 31, 2016 , 2015 , and 2014 was calculated using the following weighted average assumptions: 2016 2015 2014 Expected volatility 38.0 % 38.0 % 39.0 % Expected life (in years) 4.8 4.8 4.8 Dividend yield 1.3 % 1.0 % 1.2 % Risk-free interest rate 1.4 % 1.6 % 1.6 % Weighted average grant date fair values of stock options granted $8.46 $7.63 $6.66
Schedule of share-based compensation arrangement by share-based payment award, options, vested and expected to vest, outstanding table	Changes in outstanding stock options for the year ended December 31, 2016 were as follows: Number of Stock Options Weighted-Average Exercise Price Weighted Average Remaining Contractual Life Stock options outstanding at December 31, 2013 1,546,898 $ 17.24 3.4 years Granted 141,744 20.87 6.2 years Exercised (120,494 ) 17.89 Expired (2,400 ) 17.00 Forfeited (44,458 ) 19.99 Stock options outstanding at December 31, 2014 1,521,290 17.45 2.9 years Granted 80,800 24.20 6.2 years Exercised (463,466 ) 16.43 Forfeited (17,079 ) 20.21 Stock options outstanding at December 31, 2015 1,121,545 18.31 2.8 years Granted 67,431 27.72 6.2 years Exercised (586,132 ) 16.39 Expired (6,075 ) 22.48 Forfeited (32,673 ) 24.35 Stock options outstanding at December 31, 2016 564,096 21.04 3.3 years Exercisable at December 31, 2016 380,703 19.57 2.4 years
Schedule of fair value of options vested and instrinsic value of outstanding and exercisable options table	The fair value of stock options vested and the intrinsic value of outstanding and exercisable stock options as of December 31, were as follows: 2016 2015 2014 (in millions) Fair value of stock options vested $ 0.8 $ 1.3 $ 1.6 Intrinsic value of outstanding stock options 10.6 10.1 9.2 Intrinsic value of exercisable stock options 7.6 8.5 7.8
Schedule of share-based compensation, restricted stock and restricted stock units activity	Changes in outstanding RSUs for the year ended December 31, 2016 were as follows: Number of RSUs Weighted Average Grant Date Fair Value RSUs outstanding at December 31, 2013 358,346 $ 18.44 Granted 87,396 21.02 Forfeited (16,690 ) 20.18 Vested (122,185 ) 18.26 RSUs outstanding at December 31, 2014 306,867 19.15 Granted 112,048 24.19 Forfeited (7,749 ) 20.99 Vested (92,133 ) 19.74 RSUs outstanding at December 31, 2015 319,033 20.71 Granted 100,218 28.20 Forfeited (21,872 ) 24.87 Vested (72,995 ) 21.56 RSUs outstanding at December 31, 2016 324,384 22.55 Vested but unsettled RSUs at December 31, 2016 140,587 18.54
Schedule of fair value of RSUs vested and instrinsic value of outstanding and vested RSUs table	The grant date fair value of RSUs vested and the intrinsic value of vested RSUs for the years ended December 31, were as follows: 2016 2015 2014 (in millions) Grant date fair value of RSUs vested $ 1.6 $ 1.7 $ 2.2 Intrinsic value of RSUs vested 2.1 2.2 2.7
PSUs awarded to certain officers table	The Company has awarded PSUs to certain employees of the Company as follows: Date of Grant Target Number Awarded Fair Value on Date of Grant Aggregate Fair Value on Date of Grant (in millions) March 2014 (1) 125,340 $ 20.87 $ 2.6 March 2015 (2) 110,000 24.20 2.7 March 2016 (2) 97,236 27.72 2.7 (1) The PSUs granted in 2014 have a performance period of three years and are subject to certain performance goals, based on the Company's statutory combined ratio, with payouts that range from 0% to 200% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level. (2) The PSUs awarded in March 2015 and 2016 were awarded to certain employees of the Company and have a performance period of two years followed by an additional one year vesting period. The PSU awards are subject to certain performance goals with payouts that range from 0% to 200% of the target awards. The values shown in the table represent the aggregate number of PSUs awarded at the target level.

Statutory Matters (Tables)

Statutory Matters (Tables)	12 Months Ended
	Dec. 31, 2016
Stautory Matters [Abstract]
Statutory accounting practices disclosure table	The combined capital stock, surplus, and net income of the Company's insurance subsidiaries (EICN, ECIC, EPIC, and EAC), prepared in accordance with the statutory accounting practices (SAP) of the National Association of Insurance Commissioners (NAIC) as well as SAP permitted by the states of California, Florida, and Nevada, were as follows: December 31, 2016 2015 (in millions) Capital stock and unassigned surplus $ 622.0 $ 498.8 Paid in capital 174.9 174.9 Surplus notes 32.0 32.0 Total statutory surplus $ 828.9 $ 705.7

Accumulated Other Comprehensi43

Accumulated Other Comprehensive Income, Net (Tables)	12 Months Ended
	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of accumulated other comprehensive income (loss) table	The following table summarizes the components of accumulated other comprehensive income: Years Ended December 31, 2016 2015 (in millions) Net unrealized gain on investments, before taxes $ 114.6 $ 128.6 Deferred tax expense on net unrealized gains (40.1 ) (45.0 ) Total accumulated other comprehensive income $ 74.5 $ 83.6

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income and weighted average common shares outstanding used in earnings per share calculations table	The following table presents the net income and the weighted average shares outstanding used in the earnings per share common share calculations. Years Ended December 31, 2016 2015 2014 (in millions, except share data) Net income $ 106.7 $ 94.4 $ 100.7 Weighted average number of shares outstanding–basic 32,434,580 32,070,911 31,529,621 Effect of dilutive securities: Stock options 246,562 286,764 223,811 PSUs 222,594 155,768 264,511 RSUs 73,099 48,010 51,126 Dilutive potential shares 542,255 490,542 539,448 Weighted average number of shares outstanding–diluted 32,976,835 32,561,453 32,069,069
Antidilutive securities excluded from computation of earnings per share table	The following table presents the number of stock options, PSUs and RSUs that were excluded from the Company's calculation of diluted earnings per share. Years Ended December 31, 2016 2015 2014 Stock options excluded as the exercise price was greater than the average market price — 20,200 173,247 Stock options, PSUs and RSUs excluded under the treasury method, as the potential proceeds on settlement or exercise was greater than the value of shares acquired 89,221 257,405 260,171

Selected Quarterly Financial 45

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2016
Selecled Quarterly Financial Data (Unaudited) [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	Quarterly results for the years ended December 31, 2016 and 2015 were as follows: 2016 Quarters Ended March 31 June 30 September 30 December 31 (in millions, except per share data) Net premiums earned $ 172.6 $ 176.9 $ 173.3 $ 172.0 Net realized gains on investments 1.5 6.0 1.6 2.1 Losses and loss adjustment expenses 107.3 111.7 109.0 89.9 Commission expense 20.3 21.9 21.3 20.0 Underwriting and other operating expenses 36.3 33.6 31.7 34.5 Income tax expense 5.9 7.4 7.8 12.9 Net income 21.8 26.8 22.6 35.5 Earnings per common share: Basic 0.67 0.82 0.70 1.10 Diluted 0.66 0.81 0.69 1.08 2015 Quarters Ended March 31 June 30 September 30 December 31 (in millions, except per share data) Net premiums earned $ 159.0 $ 170.6 $ 179.0 $ 181.8 Net realized gains (losses) on investments 1.2 1.9 2.0 (15.8 ) Losses and loss adjustment expenses 106.2 101.5 115.8 105.9 Commission expense 18.7 22.9 21.0 22.8 Underwriting and other operating expenses 33.5 32.5 31.6 37.6 Income tax expense (benefit) 4.1 4.1 5.9 (9.1 ) Net income 14.0 29.2 24.5 26.7 Earnings per common share: Basic 0.44 0.91 0.76 0.83 Diluted 0.43 0.90 0.75 0.82

Schedule II - Balance Sheet Par

Schedule II - Balance Sheet Parenthetical (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amortized cost	$ 2,438,000	$ 2,358,600
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	56,226,277	55,589,454
Common stock, shares outstanding (in shares)	32,128,922	32,216,480
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Treasury stock, at cost (in shares)	24,097,355	23,372,974
Parent Company [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	56,226,277	55,589,454
Common stock, shares outstanding (in shares)	32,128,922	32,216,480
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Treasury stock, at cost (in shares)	24,097,355	23,372,974
Debt Securities [Member]
Amortized cost	$ 2,305,900	$ 2,221,100
Debt Securities [Member] | Parent Company [Member]
Amortized cost	14,700	40,200
Equity Securities [Member]
Amortized cost	116,100	137,500
Equity Securities [Member] | Parent Company [Member]
Amortized cost	$ 0	$ 46,000

Changes in Estimates (Details)

Changes in Estimates (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in Accounting Estimate [Line Items]
Unpaid losses and loss adjustment expenses		$ 2,301,000				$ 2,347,500				$ 2,301,000	$ 2,347,500	$ 2,369,700	$ 2,330,500
Amortization of deferred gain										(11,700)	(11,400)	(13,100)
Reserves reallocated to taxable years						36,900
Net income		$ 35,500	$ 22,600	$ 26,800	$ 21,800	$ 26,700	$ 24,500	$ 29,200	$ 14,000	$ 106,700	$ 94,400	$ 100,700
Basic		$ 1.10	$ 0.70	$ 0.82	$ 0.67	$ 0.83	$ 0.76	$ 0.91	$ 0.44	$ 3.29	$ 2.94	$ 3.19
Diluted		$ 1.08	$ 0.69	$ 0.81	$ 0.66	$ 0.82	$ 0.75	$ 0.90	$ 0.43	$ 3.24	$ 2.90	$ 3.14
Change to Contingent Profit Commission [Member]
Change in Accounting Estimate [Line Items]
Change in estimate of contingent commission receivable										$ 1,900	$ 2,800	$ 12,500
Amortization of deferred gain	[1]									(1,800)	(2,600)	(10,800)
Net income										$ 1,800	$ 2,600	$ 10,800
Basic										$ 0.06	$ 0.08	$ 0.34
Diluted										$ 0.05	$ 0.08	$ 0.34
Change Due to Estimated Reserves Ceded Under the LPT Agreement [Member]
Change in Accounting Estimate [Line Items]
Unpaid losses and loss adjustment expenses		$ (5,000)				$ (10,000)				$ (5,000)	$ (10,000)	$ (46,800)
Amortization of deferred gain	[2]									(3,100)	(6,400)	(31,100)
Net income										$ 3,100	$ 6,400	$ 31,100
Basic										$ 0.10	$ 0.20	$ 0.99
Diluted										$ 0.09	$ 0.20	$ 0.97
Due to change in reserves for non-taxable periods
Change in Accounting Estimate [Line Items]
Reserves reallocated to taxable years											$ 56,300	$ 13,100
Effective Income Tax Rate Reconciliation, Percent											(15.40%)	(3.40%)
Net income											$ 15,300	$ 3,600
Basic											$ 0.48	$ 0.11
Diluted											$ 0.47	$ 0.11
[1]	The cumulative adjustments to the Deferred Gain were also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised loss and LAE reserves been recognized at the inception of the LPT Agreement.
[2]	The cumulative adjustments to the Deferred Gain were also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised loss and LAE reserves been recognized at the inception of the LPT Agreement.

Summary of Significant Accoun48

Summary of Significant Accounting Policies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments	$ 2,552,600,000	$ 2,487,200,000
Restricted cash and cash equivalents	3,600,000	2,500,000
Premiums receivable from policyholders for final audit	58,400,000	53,500,000
Premiums receivable, bad debt allowance	9,800,000	12,200,000
Write-offs, net of recoveries of amounts previously written off	6,000,000	2,400,000	$ 3,400,000
Deferred policy acquisition cost, amortization expense	104,500,000	103,900,000	102,700,000
Premium Deficiency	0	0	0
Unpaid losses	$ 580,000,000	$ 628,200,000
LPT - loss expense as a percentange of losses paid, for management of LPT claims	7.00%
LPT favorable/ unfavorable difference, percentage		30.00%
LPT actual amounts paid versus expected amounts, period		every five years
LPT actual amounts paid versus expected amounts, expiration period	25
Collateralized by cash or letter of credit	$ 3,500,000
LPT collateral held in trust account	400,000,000
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible assets, gross carrying amount	17,100,000	$ 17,100,000
Intangible assets, accumulated amortization	(8,900,000)	(8,600,000)
Intangible assets, net	8,200,000	8,500,000
Amortization of intangible assets	300,000	500,000	$ 700,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Future amortization expense, year three	300,000
Future amortization expense, year four	200,000
Intangible assets, future amortization total	500,000
Funds Held in Trust, Reinsurance Agreement [Domain]
Investments	27,200,000	32,700,000
Restricted cash and cash equivalents	3,600,000	2,500,000
Licensing Agreements [Member]
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible assets, gross carrying amount	7,700,000	7,700,000
Intangible assets, net	7,700,000	7,700,000
Service Agreements [Member]
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible assets, gross carrying amount	9,400,000	9,400,000
Intangible assets, accumulated amortization	(8,900,000)	(8,600,000)
Intangible assets, net	$ 500,000	$ 800,000
Leasehold Improvements [Member]
Finite-Lived Intangible Assets, Amortization Method	amortized over three to five years
Electronic Data Processing Equipment, Software, Furniture and Equipment and Automobiles [Member]
Finite-Lived Intangible Assets, Amortization Method	straight-line method over three to seven years

New Accounting Standards Adopte

New Accounting Standards Adopted ASU (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income	$ 35,500	$ 22,600	$ 26,800	$ 21,800	$ 26,700	$ 24,500	$ 29,200	$ 14,000	$ 106,700	$ 94,400	$ 100,700
Income tax expense	$ 12,900	$ 7,800	$ 7,400	$ 5,900	$ (9,100)	$ 5,900	$ 4,100	$ 4,100	34,000	$ 5,000	$ 5,900
Accounting Standards Update No 2016-09 [Member]
Net income									1,400
Income tax expense									$ 1,400
EPS, basic and diluted									$ 0.04

Fair Value of Financial Instr50

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 2,552,600	$ 2,487,200
Cash and cash equivalents	67,200	56,600	$ 103,600	$ 34,500
Restricted cash and cash equivalents	3,600	2,500
Notes payable	32,000	32,000
Investments, fair value	2,552,600	2,487,200
Cash and cash equivalents, estimated fair value	67,200	56,600
Notes payable, fair value	$ 33,000	$ 36,600

Fair Value of Financial Instr51

Fair Value of Financial Instruments, Fair Value Inputs (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 2,552,600	$ 2,487,200
Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	2,344,400	2,288,500
Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	2,337,400	2,288,500
Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,000	0
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	127,400	120,200
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	127,400	120,200
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
US Government Agencies Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	12,800	24,400
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	12,800	24,400
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	851,600	854,500
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	851,600	854,500
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	956,700	925,300
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	956,700	925,300
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	258,000	237,900
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	258,000	237,900
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	95,500	80,300
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	95,500	80,300
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	42,400	45,900
Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	35,400	45,900
Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,000	0
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	192,200	198,700
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	187,300	198,700
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,900	0
Industrial and miscellaneous
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	167,200	178,400
Industrial and miscellaneous | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	167,200	178,400
Industrial and miscellaneous | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Industrial and miscellaneous | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Federal home loan bank stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,900
Federal home loan bank stock | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Federal home loan bank stock | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Federal home loan bank stock | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,900	0
Other equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	20,100	20,300
Other equities | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	20,100	20,300
Other equities | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Other equities | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	16,000
Short-term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Short-term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	16,000	0
Short-term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 0	$ 0

Fair Value of Financial Instr52

Fair Value of Financial Instruments Cash Equivalents at NAV and Total Cash and Cash Equivalents Carried at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents at fair value	$ 9.7	$ 56.6
Cash equivalents measured at NAV, which approximates fair value	57.5	0
Total cash and cash equivalents	$ 67.2	$ 56.6

Fair Value of Financial Instr53

Fair Value of Financial Instruments Fair Value of Financial Instruments, Reconciliation of Level 3 Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance, January 1, 2016	$ 2,487,200
Ending balance, December 31, 2016	2,552,600
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance, January 1, 2016	0
Purchases	11,900
Ending balance, December 31, 2016	$ 11,900

Investments (Details)

Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 2,438,000	$ 2,358,600
Gross unrealized gains	129,900	143,400
Gross unrealized loss	(15,300)	(14,800)
Investments	2,552,600	2,487,200
Deposit Assets
Investments	2,552,600	2,487,200
Assets Held-in-trust
Investments	2,552,600	2,487,200
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	2,305,900	2,221,100
Gross unrealized gains	53,100	77,600
Gross unrealized loss	(14,600)	(10,200)
Investments	2,344,400	2,288,500
Deposit Assets
Investments	2,344,400	2,288,500
Assets Held-in-trust
Investments	2,344,400	2,288,500
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	124,100	116,400
Gross unrealized gains	3,500	3,900
Gross unrealized loss	(200)	(100)
Investments	127,400	120,200
Deposit Assets
Investments	127,400	120,200
Assets Held-in-trust
Investments	127,400	120,200
US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	11,900	23,000
Gross unrealized gains	900	1,400
Gross unrealized loss	0	0
Investments	12,800	24,400
Deposit Assets
Investments	12,800	24,400
Assets Held-in-trust
Investments	12,800	24,400
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	833,000	809,400
Gross unrealized gains	24,700	45,100
Gross unrealized loss	(6,100)	0
Investments	851,600	854,500
Deposit Assets
Investments	851,600	854,500
Assets Held-in-trust
Investments	851,600	854,500
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	942,300	913,400
Gross unrealized gains	18,900	19,900
Gross unrealized loss	(4,500)	(8,000)
Investments	956,700	925,300
Deposit Assets
Investments	956,700	925,300
Assets Held-in-trust
Investments	956,700	925,300
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	255,900	231,800
Gross unrealized gains	4,700	7,100
Gross unrealized loss	(2,600)	(1,000)
Investments	258,000	237,900
Deposit Assets
Investments	258,000	237,900
Assets Held-in-trust
Investments	258,000	237,900
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	96,100	81,100
Gross unrealized gains	400	200
Gross unrealized loss	(1,000)	(1,000)
Investments	95,500	80,300
Deposit Assets
Investments	95,500	80,300
Assets Held-in-trust
Investments	95,500	80,300
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	42,600	46,000
Gross unrealized gains	0	0
Gross unrealized loss	(200)	(100)
Investments	42,400	45,900
Deposit Assets
Investments	42,400	45,900
Assets Held-in-trust
Investments	42,400	45,900
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	116,100	137,500
Gross unrealized gains	76,800	65,800
Gross unrealized loss	(700)	(4,600)
Investments	192,200	198,700
Deposit Assets
Investments	192,200	198,700
Assets Held-in-trust
Investments	192,200	198,700
Industrial and miscellaneous
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	100,500	126,000
Gross unrealized gains	67,400	56,800
Gross unrealized loss	(700)	(4,400)
Investments	167,200	178,400
Deposit Assets
Investments	167,200	178,400
Assets Held-in-trust
Investments	167,200	178,400
Federal home loan bank stock
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	4,900
Gross unrealized gains	0
Gross unrealized loss	0
Investments	4,900
Deposit Assets
Investments	4,900
Assets Held-in-trust
Investments	4,900
Other equities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	10,700	11,500
Gross unrealized gains	9,400	9,000
Gross unrealized loss	0	(200)
Investments	20,100	20,300
Deposit Assets
Investments	20,100	20,300
Assets Held-in-trust
Investments	20,100	20,300
Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	16,000	0
Gross unrealized gains	0
Gross unrealized loss	0
Investments	16,000
Deposit Assets
Investments	16,000
Assets Held-in-trust
Investments	16,000
Required by various state laws and regulations to hold securities or letters of credit in depository account [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments	1,009,700	881,200
Deposit Assets
Investments	1,009,700	881,200
Assets Held-in-trust
Investments	$ 1,009,700	$ 881,200

Investments, Amortized Cost and

Investments, Amortized Cost and Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amortized Cost
Due in one year or less, amortized cost	$ 136,100
Due after one year through five years, amortized cost	896,800
Due after five years through ten years, amortized cost	613,400
Due after ten years, amortized cost	265,000
Mortgage and asset-backed securities, amortized cost	394,600
Total, amortized cost	2,305,900
Estimated Fair Value
Due in one year or less, fair value	137,400
Due after one year through five years, fair value	918,600
Due after five years through ten years, fair value	625,700
Due after ten years, fair value	266,800
Mortgage and asset-backed securities, fair value	395,900
Total, fair value	$ 2,344,400	$ 2,288,500

Investments, Continuous Loss Po

Investments, Continuous Loss Position (Details) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares
Estimated Fair Value
Estimated fair value, less than 12 months	$ 527.7	$ 752.9	$ 527.7
Estimated fair value, 12 months or greater	52.8	16.9	52.8
Estimated fair value, total	580.5	769.8	580.5
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	11.2	14.8	11.2
Gross unrealized losses, 12 months or greater	3.6	0.5	3.6
Estimated unrealized loss, total position	$ 14.8	$ 15.3	$ 14.8
Number of issues in loss position, less than 12 months | shares	260	285	260
Number of issues in loss position, 12 months or greater | shares	44	10	44
Number of issues in loss position, aggregate | shares	304	295	304
Total impairments, value	$ 17	$ 5.8	$ 17.2	$ 0.5
Total impairments, number of securitites | shares	27	37	27	7
Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 491.9	$ 739.3	$ 491.9
Estimated fair value, 12 months or greater	52.8	15.2	52.8
Estimated fair value, total	544.7	754.5	544.7
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	6.6	14.2	6.6
Gross unrealized losses, 12 months or greater	3.6	0.4	3.6
Estimated unrealized loss, total position	$ 10.2	$ 14.6	$ 10.2
Number of issues in loss position, less than 12 months | shares	215	257	215
Number of issues in loss position, 12 months or greater | shares	44	5	44
Number of issues in loss position, aggregate | shares	259	262	259
US Treasury Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 27.4	$ 33.3	$ 27.4
Estimated fair value, total	27.4	33.3	27.4
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	0.1	0.2	0.1
Estimated unrealized loss, total position	$ 0.1	$ 0.2	$ 0.1
Number of issues in loss position, less than 12 months | shares	20	14	20
Number of issues in loss position, aggregate | shares	20	14	20
US States and Political Subdivisions Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 0	$ 200.9	$ 0
Estimated fair value, total	0	200.9	0
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	0	6.1	0
Estimated unrealized loss, total position	$ 0	$ 6.1	$ 0
Number of issues in loss position, less than 12 months | shares	0	50	0
Number of issues in loss position, aggregate | shares	0	50	0
Corporate Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 328.4	$ 289.5	$ 328.4
Estimated fair value, 12 months or greater	34.6	15.2	34.6
Estimated fair value, total	363	304.7	363
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	4.7	4.1	4.7
Gross unrealized losses, 12 months or greater	3.3	0.4	3.3
Estimated unrealized loss, total position	$ 8	$ 4.5	$ 8
Number of issues in loss position, less than 12 months | shares	122	101	122
Number of issues in loss position, 12 months or greater | shares	15	5	15
Number of issues in loss position, aggregate | shares	137	106	137
Residential Mortgage Backed Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 50.5	$ 137.5	$ 50.5
Estimated fair value, 12 months or greater	7.1	0	7.1
Estimated fair value, total	57.6	137.5	57.6
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	0.8	2.6	0.8
Gross unrealized losses, 12 months or greater	0.2	0	0.2
Estimated unrealized loss, total position	$ 1	$ 2.6	$ 1
Number of issues in loss position, less than 12 months | shares	24	51	24
Number of issues in loss position, 12 months or greater | shares	25	0	25
Number of issues in loss position, aggregate | shares	49	51	49
Commercial Mortgage Backed Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 51.5	$ 48	$ 51.5
Estimated fair value, total	51.5	48	51.5
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	1	1	1
Estimated unrealized loss, total position	$ 1	$ 1	$ 1
Number of issues in loss position, less than 12 months | shares	22	21	22
Number of issues in loss position, aggregate | shares	22	21	22
Asset-backed Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 34.1	$ 30.1	$ 34.1
Estimated fair value, 12 months or greater	11.1	0	11.1
Estimated fair value, total	45.2	30.1	45.2
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	0	0.2	0
Gross unrealized losses, 12 months or greater	0.1	0	0.1
Estimated unrealized loss, total position	$ 0.1	$ 0.2	$ 0.1
Number of issues in loss position, less than 12 months | shares	27	20	27
Number of issues in loss position, 12 months or greater | shares	4	0	4
Number of issues in loss position, aggregate | shares	31	20	31
Equity Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 35.8	$ 13.6	$ 35.8
Estimated fair value, 12 months or greater	0	1.7	0
Estimated fair value, total	35.8	15.3	35.8
Gross Unrealized Losses
Gross unrealized losses, less than 12 Months	4.6	0.6	4.6
Gross unrealized losses, 12 months or greater	0	0.1	0
Estimated unrealized loss, total position	$ 4.6	$ 0.7	$ 4.6
Number of issues in loss position, less than 12 months | shares	45	28	45
Number of issues in loss position, 12 months or greater | shares	0	5	0
Number of issues in loss position, aggregate | shares	45	33	45

Investments, Net Realized Gains

Investments, Net Realized Gains (Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net realized gains (losses)
Net realized gains (losses) on investments	$ 11,200	$ (10,700)	$ 16,300
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	(14,000)	(35,900)	25,300
Debt Securities [Member]
Net realized gains (losses)
Gross gains from sales	1,900	500	1,100
Gross losses from sales	(700)	(400)	0
Net realized gains (losses) on investments	1,200	100	1,100
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	(28,900)	(22,200)	23,100
Equity Securities [Member]
Net realized gains (losses)
Gross gains from sales	16,600	8,100	15,700
Gross losses from sales	(6,600)	(18,900)	(500)
Net realized gains (losses) on investments	10,000	(10,800)	15,200
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	$ 14,900	$ (13,700)	$ 2,200

Net Investment Income (Details)

Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Available-for-sale Securities	$ 2,552.6	$ 2,487.2
Investment income	76.3	74.8	$ 75
Investment expenses	(3.1)	(2.6)	(2.6)
Net investment income	73.2	72.2	72.4
Debt Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income related to fixed maturity securities and short-term investments and cash equivalents	68.5	68.8	70.7
Equity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income related to equity securities	7.4	5.9	4.2
Short-term Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income related to fixed maturity securities and short-term investments and cash equivalents	$ 0.4	$ 0.1	$ 0.1

Property and Equipment Property

Property and Equipment Property and Equipment breakout (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property and Equipment [Line Items]
Property and equipment, gross	$ 66,800	$ 64,500
Accumulated depreciation, depletion and amortization, property and equipment	44,600	39,600
Property and equipment, net	22,200	24,900
Utilities operating expense, depreciation and amortization	8,200	7,800	$ 6,300
Payments to develop software	1,300	1,200
Office Equipment [Member]
Property and Equipment [Line Items]
Property and equipment, gross	2,300	2,300
Leasehold Improvements [Member]
Property and Equipment [Line Items]
Property and equipment, gross	4,300	4,300
Computer Equipment [Member]
Property and Equipment [Line Items]
Property and equipment, gross	59,000	56,700
Automobiles [Member]
Property and Equipment [Line Items]
Property and equipment, gross	$ 1,200	$ 1,200

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal tax expense (benefit)									$ 20,300,000	$ 9,500,000	$ 6,300,000
Current state and local tax expense (benefit)									300,000	1,100,000	100,000
Current income tax expense (benefit)									20,600,000	10,600,000	6,400,000
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred income tax expense (benefit)									13,400,000	(5,600,000)	(500,000)
Income tax expense	$ 12,900,000	$ 7,800,000	$ 7,400,000	$ 5,900,000	$ (9,100,000)	$ 5,900,000	$ 4,100,000	$ 4,100,000	$ 34,000,000	5,000,000	5,900,000
Statutory federal tax rate									35.00%
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Expense computed at statutory rate									$ 49,300,000	34,800,000	37,300,000
Dividends received deduction and tax-exempt interest									(8,500,000)	(8,600,000)	(8,800,000)
Pre-privatization reserve adjustment									0	(15,300,000)	(3,600,000)
LPT deferred gain amortization									(4,700,000)	(4,900,000)	(8,400,000)
LPT reserve adjustment									(1,100,000)	(2,200,000)	(10,900,000)
Income tax reconciliation, other									(1,000,000)	1,200,000	300,000
Downward adjustment of pre-privatization unpaid loss reserve										56,300,000	13,100,000
Net income	35,500,000	$ 22,600,000	$ 26,800,000	$ 21,800,000	26,700,000	$ 24,500,000	$ 29,200,000	$ 14,000,000	106,700,000	94,400,000	100,700,000
Unrecognized tax benefits	0				0				0	0
Income Taxes Paid, Net									13,700,000	12,700,000	(1,100,000)
Deferred Tax Liabilities [Abstract]
Unrealized capital gains, net	40,100,000				45,000,000				40,100,000	45,000,000
Deferred policy acquisition cost	15,700,000				15,700,000				15,700,000	15,700,000
Intangible assets	2,900,000				3,000,000				2,900,000	3,000,000
Other deferred tax liabilities	7,900,000				7,500,000				7,900,000	7,500,000
Total deferred tax liabilities	66,600,000				71,200,000				66,600,000	71,200,000
Deferred Tax Assets [Abstract]
Loss reserves discounting for tax reporting	51,700,000				56,300,000				51,700,000	56,300,000
Unearned premiums	20,900,000				20,900,000				20,900,000	20,900,000
Allowance for bad debt	3,400,000				4,300,000				3,400,000	4,300,000
Stock based compensation	4,400,000				4,100,000				4,400,000	4,100,000
Accrued liabilities	8,100,000				8,400,000				8,100,000	8,400,000
Minimum tax credit	27,800,000				28,000,000				27,800,000	28,000,000
Net operating loss carry forward	0				8,700,000				0	8,700,000
Other deferred tax assets	9,700,000				8,400,000				9,700,000	8,400,000
Total deferred tax assets	126,000,000				139,100,000				126,000,000	139,100,000
Deferred income taxes, net	$ 59,400,000				$ 67,900,000				59,400,000	67,900,000
Change Due to Estimated Reserves Ceded Under the LPT Agreement [Member]
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Net income									3,100,000	6,400,000	31,100,000
Change to Contingent Profit Commission [Member]
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Net income									$ 1,800,000	$ 2,600,000	$ 10,800,000

Liability for Unpaid Losses a61

Liability for Unpaid Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Unpaid losses and LAE, gross of reinsurance, at beginning of period			$ 2,347,500	$ 2,369,700	$ 2,330,500
Loss reinsurance recoverable, excluding bad debt, on unpaid losses			628,200	669,500	743,100
Net unpaid losses and LAE at beginning of period			1,719,300	1,700,200	1,587,400
Losses and LAE, net of reinsurance, incurred in:
Current year			452,900	456,900	503,800
Prior years	$ 16,900	$ 8,500	(18,400)	(7,200)	4,600
Total net losses and LAE incurred during the period			434,500	449,700	508,400
Deduct payments for losses and LAE, net of reinsurance, related to:
Current year			78,700	75,400	75,900
Prior years			354,100	355,200	319,700
Total net payments for losses and LAE during the period			432,800	430,600	395,600
Ending unpaid losses and LAE, net of reinsurance	1,721,000	1,719,300	1,721,000	1,719,300	1,700,200
Loss reinsurance recoverable, excluding bad debt, on unpaid losses	580,000	628,200	580,000	628,200	669,500
Unpaid losses and LAE, gross of reinsurance, at end of period	2,301,000	2,347,500	2,301,000	2,347,500	$ 2,369,700
Salvage and subrogation recoveries, value	$ 28,100	$ 26,800	28,100	26,800
Voluntary risk business
Losses and LAE, net of reinsurance, incurred in:
Prior years			17,000	9,000
Involuntary assigned risk business
Losses and LAE, net of reinsurance, incurred in:
Prior years			$ 1,400	$ (1,800)

Liability for Unpaid Losses a62

Liability for Unpaid Losses and Loss Adjustment Expenses Historical Incurred Losses and LAE (Details) $ in Millions	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	[1]	Dec. 31, 2014USD ($)	[1]	Dec. 31, 2013USD ($)	[1]	Dec. 31, 2012USD ($)	[1]	Dec. 31, 2011USD ($)	[1]	Dec. 31, 2010USD ($)	[1]	Dec. 31, 2009USD ($)	[1]	Dec. 31, 2008USD ($)	[1]	Dec. 31, 2007USD ($)	[1]
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	$ 3,669.6
Cumulative paid losses and LAE, net of reinsurance	2,394.2
Liabilities for unpaid losses and LAE, net of reinsurance	1,621.6
Accident years prior to 2007
Claims Development [Line Items]
Cumulative paid losses and LAE, net of reinsurance	346.2
Accident year 2007
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	346.6	$ 339.2		$ 334.6		$ 334.7		$ 332.7		$ 332.9		$ 340.3		$ 340.1		$ 341.8		$ 349.4
IBNR	$ 15.1
Cumulative number of reported claims	31,326
Cumulative paid losses and LAE, net of reinsurance	$ 302.3	297.2		288.3		280.2		270		256.2		236.7		208.9		165.3		$ 74.2
Accident year 2008
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	341.4	343.8		336.9		335.1		329.5		329.2		317.8		315.3		315.9
IBNR	$ 16.2
Cumulative number of reported claims	28,082
Cumulative paid losses and LAE, net of reinsurance	$ 300.7	293.6		284.2		271.1		255.3		234.7		201.8		155.4		$ 71.1
Accident year 2009
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	290.5	291.2		283.7		283.6		280.1		279		266.9		255.4
IBNR	$ 16.3
Cumulative number of reported claims	22,666
Cumulative paid losses and LAE, net of reinsurance	$ 249.5	242.3		232.1		219.3		202		174.1		130.6		$ 59
Accident year 2010
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	259.9	262		250.2		246.1		228.1		224.4		204.9
IBNR	$ 23.8
Cumulative number of reported claims	18,533
Cumulative paid losses and LAE, net of reinsurance	$ 215.4	206.2		190.7		171.7		143.8		105.6		$ 47.1
Accident year 2011
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	292.6	296.3		277.4		272		267.3		253.7
IBNR	$ 34
Cumulative number of reported claims	19,553
Cumulative paid losses and LAE, net of reinsurance	$ 230.1	217.5		193.8		162.6		115.1		$ 47.4
Accident year 2012
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	388.2	386.4		360.9		359.9		348.8
IBNR	$ 60.5
Cumulative number of reported claims	25,930
Cumulative paid losses and LAE, net of reinsurance	$ 289.9	261.4		214.2		148.3		$ 58.6
Accident year 2013
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	472.6	478.6		460.6		452.6
IBNR	$ 90.1
Cumulative number of reported claims	28,740
Cumulative paid losses and LAE, net of reinsurance	$ 317.4	263.8		184.4		$ 68.5
Accident year 2014
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	432.9	445.8		463.4
IBNR	$ 107.4
Cumulative number of reported claims	28,231
Cumulative paid losses and LAE, net of reinsurance	$ 248.9	172.7		$ 65.3
Accident year 2015
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	425.8	422.2
IBNR	$ 135.6
Cumulative number of reported claims	26,560
Cumulative paid losses and LAE, net of reinsurance	$ 174.5	$ 65.5
Accident year 2016
Claims Development [Line Items]
Incurred losses and LAE, net of reinsurance	419
IBNR	$ 226.1
Cumulative number of reported claims	21,239
Cumulative paid losses and LAE, net of reinsurance	$ 65.6
[1]	Data presented for these calendar years is required supplementary information, which is unaudite

Liability for Unpaid Losses a63

Liability for Unpaid Losses and Loss Adjustment Expenses Reconciliation of Claims Development to Aggregate Carrying Amount of the Liability for Unpaid Losses and LAE (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for unpaid losses and LAE, net of reinsurance	$ 1,621,600
Reinsurance recoverable on unpaid losses	580,000	$ 628,200	$ 669,500	$ 743,100
Unallocated LAE	99,400
Unpaid losses and loss adjustment expenses	$ 2,301,000	$ 2,347,500	$ 2,369,700	$ 2,330,500

Liability for Unpaid Losses a64

Liability for Unpaid Losses and Loss Adjustment Expenses Short Duration Insurance Contracts, Historcial Claims Duration (Details)	Dec. 31, 2016
Average annual percentage payout of incurred claims by age, net of reinsurance
Year one	17.30%
Year two	24.40%
Year three	15.40%
Year four	10.30%
Year five	6.70%
Year six	4.70%
Year seven	3.50%
Year eight	2.50%
Year nine	2.30%
Year ten	1.50%

Reinsurance Reinsurance Premium

Reinsurance Reinsurance Premium Note (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Premiums Written, Net
Direct premiums, written	$ 691	$ 684.9	$ 686.8
Assumed premiums written	10.4	12.8	10.9
Gross premiums, written	701.4	697.7	697.7
Ceded premiums written	(6.8)	(8.4)	(10.1)
Premiums written, net	694.6	689.3	687.6
Premiums Earned, Net
Direct premiums earned	691	686	684.3
Assumed premiums earned	10.6	12.8	10.3
Gross premiums, earned	701.6	698.8	694.6
Ceded premiums earned	(6.8)	(8.4)	(10.1)
Premiums earned, net	694.8	690.4	684.5
Ceded losses and LAE incurred	$ 0.1	$ 10.1	$ 17.2

Reinsurance Excess of Loss (Det

Reinsurance Excess of Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Effects of Reinsurance [Line Items]
Retention amount on a per occurrence basis		$ 7	$ 5
Excess of retention amount on a per occurrence basis		$ 193	$ 195
Scenario, Forecast [Member]
Effects of Reinsurance [Line Items]
Retention amount on a per occurrence basis	$ 10
Maximum reinsurance for losses from single occurence or event	$ 200

Reinsurance LPT Agreement (Deta

Reinsurance LPT Agreement (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reinsurance Agreement [Line Items]
Unpaid losses		$ 580,000	$ 628,200
Recoverables was related to the LPT agreement		$ 465,500	498,000
Reinsurance quota share, percentage		100.00%
Ceded premiums written		$ 6,800	8,400	$ 10,100
Coverage provided under LPT agreement		2,000,000
Paid losses and LAE claims related to LPT		722,700
Amortization of deferred gain		11,700	11,400	13,100
LPT Agreement [Member]
Reinsurance Agreement [Line Items]
Liabilities for the incurred but unpaid losses and LAE related to claims prior to July 1, 1995		1,500,000
Ceded premiums written		775,000
Change Due to Estimated Reserves Ceded Under the LPT Agreement [Member]
Reinsurance Agreement [Line Items]
Amortization of deferred gain	[1]	3,100	6,400	31,100
Change to Contingent Profit Commission [Member]
Reinsurance Agreement [Line Items]
Amortization of deferred gain	[2]	$ 1,800	$ 2,600	$ 10,800
[1]	The cumulative adjustments to the Deferred Gain were also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised loss and LAE reserves been recognized at the inception of the LPT Agreement.
[2]	The cumulative adjustments to the Deferred Gain were also recognized in losses and LAE incurred in the Company's Consolidated Statements of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised loss and LAE reserves been recognized at the inception of the LPT Agreement.

Notes Payable Outstanding (Deta

Notes Payable Outstanding (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Notes payable	$ 32,000	$ 32,000
Dekania Surplus Note [Member]
Debt Instrument [Line Items]
Notes payable	$ 10,000	10,000
Notes payable, maturity date	Apr. 30, 2034
Notes payable, callable	2,009
Interest rate, basis points in excess of the 90-day LIBOR	425
Cash paid for interest	$ 500	500	$ 500
Accrued interest	100	100
ICONS Surpuls Note [Member]
Debt Instrument [Line Items]
Notes payable	$ 12,000	12,000
Notes payable, maturity date	May 26, 2034
Notes payable, callable	2,009
Interest rate, basis points in excess of the 90-day LIBOR	425
Cash paid for interest	$ 600	600	500
Accrued interest	100	100
Alesco Surplus Note [Member]
Debt Instrument [Line Items]
Notes payable	$ 10,000	10,000
Notes payable, maturity date	Dec. 15, 2034
Notes payable, callable	2,009
Interest rate, basis points in excess of the 90-day LIBOR	405
Cash paid for interest	$ 500	400	400
Accrued interest	$ 100	100
Line of Credit [Member]
Debt Instrument [Line Items]
Notes payable			60,000	$ 70,000	$ 80,000	$ 90,000	$ 100,000
Line of credit, percentage above prime rate	1.75%
Line of credit, percentage above LIBOR rate	1.75%
Cash paid for interest		1,300	$ 1,400
Line of credit facility, decrease, repayments		$ 60,000

Notes Payable Principal payment

Notes Payable Principal payment obligations on notes payable outstanding (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Capitalization, Long-term Debt [Line Items]
Repayments of principal in next twelve months	$ 0
Repayments of principal in year two	0
Repayments of principal in year three	0
Repayments of principal in year four	0
Repayments of principal in year five	0
Repayments of principal after year five	32,000
Notes payable	$ 32,000	$ 32,000

Commitments and Contingencies F

Commitments and Contingencies Future Lease Payments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies [Abstract]
Remaining lease terms expire over the next	6 years
Future lease payments for non-cancelable operating and capital leases, in years	5 years
Operating Leases, Future Minimum Payments Due [Abstract]
Operating leases, future minimum payments due, current	$ 5.1
Operating leases, future minimum payments, due in two years	3.7
Operating leases, future minimum payments, due in three years	3.1
Operating leases, future minimum payments, due in four years	2.5
Operating leases, future minimum payments, due in five years	1.1
Operating leases, future minimum payments, due thereafter	0.1
Operating leases, future minimum payments due	15.6
Capital Leases, Future Minimum Payments Due [Abstract]
Capital leases, future minimum payments due, current	0.3
Capital leases, future minimum payments due in two years	0.2
Capital leases, future minimum payments due in three years	0.1
Capital leases, future minimum payments due in four years	0.1
Capital leases, future minimum payments due in five years	0.1
Capital leases, Future minimum payments due thereafter	0
Capital leases, future minimum payments due	0.8
Future interest charges included in capital lease payments	0.1
Facilities rent expense	$ 4.9	$ 4.9	$ 4.8

Commitments and Contingencies P

Commitments and Contingencies Property held under capital leases is included in property and equipment (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Property held under capital leases
Accumulated depreciation, depletion and amortization, property and equipment	$ (44.6)	$ (39.6)
Computers and software
Property held under capital leases
Property held under captial leases	0	0.4
Automobiles [Member]
Property held under capital leases
Property held under captial leases	1.2	1.2
Assets Held under Capital Leases [Member]
Property held under capital leases
Property held under captial leases	1.2	1.6
Accumulated depreciation, depletion and amortization, property and equipment	(0.6)	(1)
Total property held under capital leases	$ 0.6	$ 0.6

Commitments and Contingencies C

Commitments and Contingencies Contingencies Surrounding Insurance Assessments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Amount of Insurance-related assessment liability	$ 18.6	$ 22
Payment period for assessment liability based on individual states regulations	one to eighty year periods
Other assets, prepaid policy surcharges	$ 21.6	$ 21.4
Expected realization period for assets related to policy surcharges	one to ten year periods

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended	120 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Feb. 16, 2016
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount			$ 50
Stock repurchased during period, shares	724,381	24,097,355
Accelerated share repurchases, final price paid per share	$ 29.08	$ 15.92
Stock Repurchased During Period, Value	$ 21.1

Stock-Based Compensation Expens

Stock-Based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares reserved for grants	7,105,838
Stock-based compensation expense [Abstract]
Stock-based compensation expense	$ 5.8	$ 4.6	$ 6
Less: related tax benefit	2	1.6	2.1
Net stock-based compensation expense	3.8	3	3.9
Stock Option [Member]
Stock-based compensation expense [Abstract]
Stock-based compensation expense	0.7	1	1.2
Restricted stock units (RSUs)
Stock-based compensation expense [Abstract]
Stock-based compensation expense	1.9	2	1.9
Performance shares units [Member]
Stock-based compensation expense [Abstract]
Stock-based compensation expense	$ 3.2	$ 1.6	$ 2.9

Stock-Based Compensation Fair M

Stock-Based Compensation Fair Market Value of Stock Options Granted, Calculated (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Market Value of Stock Options Granted, Calculated [Abstract]
Expected volatility	38.00%	38.00%	39.00%
Expected life (in years)	4 years 274 days	4 years 274 days	4 years 274 days
Dividend yield	1.30%	1.00%	1.20%
Risk free interest rate	1.40%	1.60%	1.60%
Weighted average grant date fair value	$ 8.46	$ 7.63	$ 6.66

Stock-Based Compensation Change

Stock-Based Compensation Changes in Outstanding Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value	$ 8.46	$ 7.63	$ 6.66
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options or share units	564,096	1,121,545	1,521,290	1,546,898
Number of options or share units, granted	67,431	80,800	141,744
Stock-options exercised, shares	(586,132)	(463,466)	(120,494)
Number of options or share units, expired	(6,075)		(2,400)
Number of options or share units, forfeited	(32,673)	(17,079)	(44,458)
Number of exercisable options or share units	380,703
Weighted average exercise price, grants	$ 27.72	$ 24.20	$ 20.87
Weighted average exercise price, exercises	16.39	16.43	17.89
Weighted average exercise price, expirations	22.48		17
Weighted average exercise price, forfeitures	24.35	20.21	19.99
Weighted average exercise price, outstanding	21.04	$ 18.31	$ 17.45	$ 17.24
Weighted average exercisable price	$ 19.57
Weighted average remaining contractual life	3 years 125 days	2 years 300 days	2 years 324 days	3 years 164 days
Share-based compensation expense, deferred	$ 1.1
Share-based compensation expense, Period for Recognition	39 months
Options vested, fair value	$ 0.8	$ 1.3	$ 1.6
Options outstanding, intrinsic value	10.6	10.1	9.2
Options exercisable, intrinsic value	7.6	8.5	7.8
Options exercised, intrinsic value	$ 7.6	$ 4	$ 0.5
Stock Options Granted [Domain]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average remaining contractual life	6 years 73 days	6 years 73 days	6 years 73 days
Stock Options Exercisable [Domain]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average remaining contractual life	2 years 160 days
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service vesting period for options awarded	4 years
Vesting rights for options awarded	vest 25% on or after each of the subsequent four anniversaries of such date
Number of outstanding options or share units	324,384	319,033	306,867	358,346
Number of options or share units, granted	100,218	112,048	87,396
Number of options or share units, forfeited	(21,872)	(7,749)	(16,690)
Number of vested options or share units	(72,995)	(92,133)	(122,185)
Weighted average exercise price, grants	$ 28.20	$ 24.19	$ 21.02
Weighted average exercise price, forfeitures	24.87	20.99	20.18
Weighted average exercise price, vested	21.56	19.74	18.26
Weighted average grant date fair value	$ 22.55	$ 20.71	$ 19.15	$ 18.44
Share-based compensation expense, deferred	$ 3.5
Share-based compensation expense, Period for Recognition	39 months
Options vested, fair value	$ 1.6	$ 1.7	$ 2.2
Options outstanding, intrinsic value	12.8	8.7	7.2
Options exercisable, intrinsic value	$ 2.1	$ 2.2	$ 2.7
Restricted Stock Units Vested but Unsettled [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options or share units	140,587
Weighted average grant date fair value	$ 18.54

Stock-Based Compensation Perfor

Stock-Based Compensation Performance Share Awards (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2014		Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards, minimum payout	0.00%		0.00%
Performane share awards, maximum payout	200.00%		200.00%
Performance share awards, expected target	182.00%				200.00%
Performance share awards, ultimate payout			100.00%
Performance shares units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service vesting period for options awarded			3 years
Number of outstanding options or share units	97,236	[1]	125,340	[2]	110,000	[1]
Share-based compensation options, exercise price on grant date	$ 27.72	[1]	$ 20.87	[2]	$ 24.20	[1]
Fair value of awards awarded on grant date	$ 2.7	[1]	$ 2.6	[2]	$ 2.7	[1]
Share-based compensation expense, deferred	$ 4.7
Share-based compensation expense, Period for Recognition	24 months
[1]	The PSUs awarded in March 2015 and 2016 were awarded to certain employees of the Company and have a performance period of two years followed by an additional one year vesting period. The PSU awards are subject to certain performance goals with payouts that range from 0% to 200% of the target awards. The values shown in the table represent the aggregate number of PSUs awarded at the target level.
[2]	The PSUs granted in 2014 have a performance period of three years and are subject to certain performance goals, based on the Company's statutory combined ratio, with payouts that range from 0% to 200% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level.

Statutory Matters Statutory Mat

Statutory Matters Statutory Matters (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 06, 2017	Jun. 22, 2017
Statutory Accounting Practices [Line Items]
Capital stock and unassigned surplus	$ 622,000	$ 498,800
Paid in capital	174,900	174,900
Surplus notes	32,000	32,000
Total statutory surplus	828,900	705,700
SAP, net income amount	101,400	87,800	$ 58,600
Total stockholders’ equity	$ 840,600	$ 760,800
Will maintain a risk based capital (RBC) level of at least	350.00%
EICN
Statutory Accounting Practices [Line Items]
Capital stock and unassigned surplus	$ 152,100
Extraordinary dividends, approves or does not disapprove the payment within	30 days
Percentage of surplus of EICN's statutory surplus as regards to policyholders	10.00%
SAP, dividends paid with approval of regulatory agency	$ 358,300
EPIC
Statutory Accounting Practices [Line Items]
Percentage of surplus used to calculate the lesser of 10% of surplus or net income, not including realized capital gains, plus a 2-year carry forward.	10.00%
Percentage of surplus used to calculate 10% of surplus, with dividends payable limited to unassigned funds minus 25% of unrealized capital gains	10.00%
Percentage of surplus used to calculate the lesser of 10% of surplus or net investment income plus a 3-year carry forward with dividends payable limited to unassigned funds minus 25% of unrealized capital gains	10.00%
Percentage of unassigned gains used to calculate 10% of surplus, with dividends payable limited to unassigned funds minus 25% of unrealized capital gains	25.00%
Percentage of unassigned gains used to calculate the lesser of 10% of surplus or net investment income plus a 3-year carry forward with dividends payable limited to unassigned funds minus 25% of unrealized capital gains	25.00%
SAP, dividends paid with approval of regulatory agency	$ 179,800
EAC
Statutory Accounting Practices [Line Items]
SAP, dividends paid with approval of regulatory agency	$ 32,200
EAC | Scenario, Forecast [Member]
Statutory Accounting Practices [Line Items]
Maximum dividends that may be paid without prior approval				$ 18,000
ECIC
Statutory Accounting Practices [Line Items]
ECIC must initiate discussions of its business plan with the California DOI if its premium to policyholder surplus ratio exceeds	1.5 to 1
ECIC will not exceed a ratio of premium to policyholder surplus of	2 to 1
If at any time ECIC's policyholder surplus decreases to	80.00%
Dividends paid, without approval of regulatory agency	$ 33,500
Maximum dividends that may be paid without prior approval	4,600
ECIC | Scenario, Forecast [Member]
Statutory Accounting Practices [Line Items]
Maximum dividends that may be paid without prior approval					$ 38,100
EAC and EPIC
Statutory Accounting Practices [Line Items]
Total statutory surplus	$ 4,000
Florida statute section 624.408 requires EPIC and EAC to maintain minimum capital and surplus of the greater of $4.0 million or 10% of total liabilities.	10.00%
Used to calculate ratio of written premium to surplus	1.25
Net gross premiums to surplus ratio. Florida statute section 624.4095 requires net gross premiums times 1.25 not exceed this ratio.	10-to-1
Net written premiums to surplus ratio. Florida statute section 624.4095 requires net written premiums times 1.25 not exceed this ratio.	4-to-1

Accumulated Other Comprehensi79

Accumulated Other Comprehensive Income, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net unrealized gain on investments, before taxes	$ 114,600	$ 128,600
Deferred tax expense	(40,100)	(45,000)
Total accumulated other comprehensive income, net	$ (74,500)	$ (83,600)

Employee Benefit and Retireme80

Employee Benefit and Retirement Plans Employee Benefit and Retirement Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Benefit and Retirement Plans [Abstract]
Safe habor matching, 100%	100.00%
Employee contributions, 100% match, percentage	3.00%
Safe harbor matching 50%	50.00%
Employee contributions 50% match, percentage	3.00%
Employee contributions, maximum match, percentage	5.00%
Company's contributions to Employers 401(k)	$ 1.9	$ 1.8	$ 1.7

Earnings Per Share Earnings Per

Earnings Per Share Earnings Per Share (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income	$ 35,500	$ 22,600	$ 26,800	$ 21,800	$ 26,700	$ 24,500	$ 29,200	$ 14,000	$ 106,700	$ 94,400	$ 100,700
Weighted average number of shares outstanding - basic									32,434,580	32,070,911	31,529,621
Effect of diluted securities:									542,255	490,542	539,448
Weighted average number of shares outstanding - diluted									32,976,835	32,561,453	32,069,069
Employee Stock Option [Member]
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Effect of diluted securities:									246,562	286,764	223,811
Performance shares units [Member]
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Effect of diluted securities:									222,594	155,768	264,511
Restricted stock units (RSUs)
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Effect of diluted securities:									73,099	48,010	51,126

Earnings Per Share Antidilutive

Earnings Per Share Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of EPS	89,221	257,405	260,171
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of EPS	0	20,200	173,247

Selected Quarterly Financial 83

Selected Quarterly Financial Data Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Prior Year Claims and Claims Adjustment Expense	$ 16,900				$ 8,500				$ (18,400)	$ (7,200)	$ 4,600
Net premiums earned	172,000	$ 173,300	$ 176,900	$ 172,600	181,800	$ 179,000	$ 170,600	$ 159,000	694,800	690,400	684,500
Net realized gains (losses) on investments	2,100	1,600	6,000	1,500	(15,800)	2,000	1,900	1,200	11,200	(10,700)	16,300
Losses and loss adjustment expenses	89,900	109,000	111,700	107,300	105,900	115,800	101,500	106,200	417,900	429,400	453,400
Commission expense	20,000	21,300	21,900	20,300	22,800	21,000	22,900	18,700	83,500	85,400	81,400
Underwriting and other operating expenses	34,500	31,700	33,600	36,300	37,600	31,600	32,500	33,500	136,100	135,200	129,100
Income tax expense	12,900	7,800	7,400	5,900	(9,100)	5,900	4,100	4,100	34,000	5,000	5,900
Net income	$ 35,500	$ 22,600	$ 26,800	$ 21,800	$ 26,700	$ 24,500	$ 29,200	$ 14,000	$ 106,700	$ 94,400	$ 100,700
Earnings per common share (Note 18):
Basic	$ 1.10	$ 0.70	$ 0.82	$ 0.67	$ 0.83	$ 0.76	$ 0.91	$ 0.44	$ 3.29	$ 2.94	$ 3.19
Diluted	$ 1.08	$ 0.69	$ 0.81	$ 0.66	$ 0.82	$ 0.75	$ 0.90	$ 0.43	$ 3.24	$ 2.90	$ 3.14
Reserves reallocated to taxable years					$ 36,900
Total impairments, value					17,000				$ 5,800	$ 17,200	$ 500
Due to change in reserves for non-taxable periods
Condensed Financial Statements, Captions [Line Items]
Income tax expense					$ 11,500
Net income										$ 15,300	$ 3,600
Earnings per common share (Note 18):
Basic										$ 0.48	$ 0.11
Diluted										$ 0.47	$ 0.11
Reserves reallocated to taxable years										$ 56,300	$ 13,100

Schedule II. Condensed Financ84

Schedule II. Condensed Financial Information of Registrant (Condensed Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments
Investment in fixed maturity securities at fair value (amortized cost $14.7 in 2016 and $40.2 in 2015)	$ 2,552,600	$ 2,487,200
Equity securities at fair value (amortized cost $46.0 in 2015)	192,200	198,700
Total investments	2,552,600	2,487,200
Cash and cash equivalents	67,200	56,600	$ 103,600	$ 34,500
Accrued investment income	20,600	20,600
Deferred income taxes, net	59,400	67,900
Other assets	34,600	40,900
Total assets	3,773,400	3,755,800
Liabilities and stockholders’ equity
Accounts payable and accrued expenses	24,200	24,100
Other liabilities	41,600	40,500
Total liabilities	2,932,800	2,995,000
Stockholders’ equity:
Common stock, $0.01 par value; 150,000,000 shares authorized; 56,226,277 and 55,589,454 shares issued and 32,128,922 and 32,216,480 shares outstanding at December 31, 2016 and 2015, respectively	600	600
Preferred stock, $0.01 par value; 25,000,000 shares authorized; none issued	0	0
Additional paid-in capital	372,000	357,200
Retained earnings	777,200	682,000
Accumulated other comprehensive income, net of tax	74,500	83,600
Treasury stock, at cost (24,097,355 shares at December 31, 2016 and 23,372,974 shares at December 31, 2015)	(383,700)	(362,600)
Total stockholders’ equity	840,600	760,800
Total liabilities and stockholders’ equity	3,773,400	3,755,800
Parent Company [Member]
Investments
Investment in subsidiaries	757,500	647,100
Investment in fixed maturity securities at fair value (amortized cost $14.7 in 2016 and $40.2 in 2015)	16,000	42,200
Equity securities at fair value (amortized cost $46.0 in 2015)	0	51,600
Total investments	773,500	740,900
Cash and cash equivalents	41,400	1,400	$ 10,900	$ 6,400
Accrued investment income	300	0
Intercompany receivable	0	200
Federal income taxes recoverable	9,600	1,700
Deferred income taxes, net	20,000	20,600
Other assets	700	1,500
Total assets	845,500	766,300
Liabilities and stockholders’ equity
Accounts payable and accrued expenses	4,800	5,200
Intercompany payable	100	0
Other liabilities	0	300
Total liabilities	4,900	5,500
Stockholders’ equity:
Common stock, $0.01 par value; 150,000,000 shares authorized; 56,226,277 and 55,589,454 shares issued and 32,128,922 and 32,216,480 shares outstanding at December 31, 2016 and 2015, respectively	600	600
Preferred stock, $0.01 par value; 25,000,000 shares authorized; none issued	0	0
Additional paid-in capital	372,000	357,200
Retained earnings	777,200	682,000
Accumulated other comprehensive income, net of tax	74,500	83,600
Treasury stock, at cost (24,097,355 shares at December 31, 2016 and 23,372,974 shares at December 31, 2015)	(383,700)	(362,600)
Total stockholders’ equity	840,600	760,800
Total liabilities and stockholders’ equity	$ 845,500	$ 766,300

Schedule II. Condensed Financ85

Schedule II. Condensed Financial Information of Registrant (Condensed Balance Sheets Parenthetical) (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fixed maturity securities, amortized cost	$ 2,438,000	$ 2,358,600
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	56,226,277	55,589,454
Common stock, shares outstanding (in shares)	32,128,922	32,216,480
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Treasury stock, at cost (in shares)	24,097,355	23,372,974
Parent Company [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	56,226,277	55,589,454
Common stock, shares outstanding (in shares)	32,128,922	32,216,480
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Treasury stock, at cost (in shares)	24,097,355	23,372,974
Debt Securities [Member]
Fixed maturity securities, amortized cost	$ 2,305,900	$ 2,221,100
Debt Securities [Member] | Parent Company [Member]
Fixed maturity securities, amortized cost	14,700	40,200
Equity Securities [Member]
Fixed maturity securities, amortized cost	116,100	137,500
Equity Securities [Member] | Parent Company [Member]
Fixed maturity securities, amortized cost	$ 0	$ 46,000

Schedule II. Condensed Financ86

Schedule II. Condensed Financial Information of Registrant (Condensed Statements of Income) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Net investment income									$ 73,200	$ 72,200	$ 72,400
Net realized gains on investments	$ 2,100	$ 1,600	$ 6,000	$ 1,500	$ (15,800)	$ 2,000	$ 1,900	$ 1,200	11,200	(10,700)	16,300
Total revenues									779,800	752,100	773,500
Expenses
Interest expense									1,600	2,700	3,000
Total expenses									639,100	652,700	666,900
Income tax expense	12,900	7,800	7,400	5,900	(9,100)	5,900	4,100	4,100	34,000	5,000	5,900
Net income	$ 35,500	$ 22,600	$ 26,800	$ 21,800	$ 26,700	$ 24,500	$ 29,200	$ 14,000	$ 106,700	$ 94,400	$ 100,700
Earnings per common share for the stated periods (Note 18):
Basic	$ 1.10	$ 0.70	$ 0.82	$ 0.67	$ 0.83	$ 0.76	$ 0.91	$ 0.44	$ 3.29	$ 2.94	$ 3.19
Diluted	$ 1.08	$ 0.69	$ 0.81	$ 0.66	$ 0.82	$ 0.75	$ 0.90	$ 0.43	3.24	2.90	3.14
Cash dividends declared per common share									$ 0.36	$ 0.24	$ 0.24
Parent Company [Member]
Revenues
Net investment income									$ 1,900	$ 4,000	$ 5,200
Net realized gains on investments									8,000	2,400	5,800
Total revenues									9,900	6,400	11,000
Expenses
Other operating expenses									13,800	13,800	13,500
Interest expense									0	1,100	1,400
Total expenses									13,800	14,900	14,900
Income (loss) before income taxes and equity in earnings of subsidiaries									(3,900)	(8,500)	(3,900)
Income tax expense									(3,500)	(3,300)	(2,600)
Net income (loss) before equity in earnings of subsidiaries									(400)	(5,200)	(1,300)
Equity in net income of subsidiaries									107,100	99,600	102,000
Net income									$ 106,700	$ 94,400	$ 100,700
Earnings per common share for the stated periods (Note 18):
Basic									$ 3.29	$ 2.94	$ 3.19
Diluted									$ 3.24	$ 2.90	$ 3.14

Schedule II. Condensed Financ87

Schedule II. Condensed Financial Information of Registrant (Condensed Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income	$ 35,500	$ 22,600	$ 26,800	$ 21,800	$ 26,700	$ 24,500	$ 29,200	$ 14,000	$ 106,700	$ 94,400	$ 100,700
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Realized gains on investments									(11,200)	10,700	(16,300)
Stock-based compensation									5,800	4,600	6,000
Excess Tax Benefit from Share-based Compensation, Operating Activities									0	1,200	1,200
Amortization of premium on investments, net									14,600	12,800	10,600
Deferred income tax expense									13,400	(5,600)	(500)
Change in operating assets and liabilities:
Accounts payable, accrued expenses and other liabilities									(4,200)	8,600	12,800
Federal income taxes									7,700	(3,900)	6,500
Other									(500)	(7,000)	(10,500)
Net cash provided by operating activities									122,800	116,400	171,900
Investing activities
Purchases of fixed maturity securities									(466,800)	(476,900)	(378,000)
Purchase of equity securities									(49,100)	(85,100)	(29,500)
Proceeds from sale of fixed maturity securities									132,400	105,400	47,900
Proceeds from maturities and redemptions of investments									230,600	323,900	251,100
Proceeds from sale of equity securities									80,400	34,700	36,500
Capital Contributions to subsidiary									(8,000)	0	0
Restricted cash used in investing activities									(1,100)	8,300	(4,200)
Net cash provided by investing activities									(88,600)	(101,200)	(86,700)
Financing activities
Acquisition of common stock									(21,100)	0	0
Cash transactions related to stock-based compensation									9,000	4,800	1,600
Dividends paid to stockholders									(11,500)	(7,700)	(7,600)
Payments on notes payable and capital leases									0	(60,500)	(11,300)
Excess tax benefits from stock-based compensation									0	1,200	1,200
Net cash used in financing activities									(23,600)	(62,200)	(16,100)
Net increase (decrease) in cash and cash equivalents									10,600	(47,000)	69,100
Cash and cash equivalents at the beginning of the period				56,600				103,600	56,600	103,600	34,500
Cash and cash equivalents at the end of the period	67,200				56,600				67,200	56,600	103,600
Parent Company [Member]
Operating activities
Net income									106,700	94,400	100,700
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in net income of subsidiaries									107,100	99,600	102,000
Realized gains on investments									(8,000)	(2,400)	(5,800)
Stock-based compensation									5,800	4,600	6,000
Excess Tax Benefit from Share-based Compensation, Operating Activities									0	(1,200)	(1,200)
Amortization of premium on investments, net									400	900	1,000
Deferred income tax expense									2,900	(4,600)	(2,300)
Change in operating assets and liabilities:
Accounts payable, accrued expenses and other liabilities									(700)	1,700	1,200
Federal income taxes									(7,900)	4,900	800
Other assets									(800)	(400)	(900)
Intercompany payable/receivable									300	100	(1,400)
Other									400	(1,200)	(900)
Net cash provided by operating activities									(7,200)	400	(1,200)
Investing activities
Purchases of fixed maturity securities									(31,000)	(21,600)	(12,000)
Purchase of equity securities									(3,600)	(19,000)	(20,700)
Proceeds from sale of fixed maturity securities									0	18,300	4,100
Proceeds from maturities and redemptions of investments									24,900	45,500	32,600
Proceeds from sale of equity securities									88,500	24,000	20,600
Restricted cash used in investing activities									0	4,600	(4,100)
Net cash provided by investing activities									70,800	51,800	20,500
Financing activities
Acquisition of common stock									(21,100)	0	0
Cash transactions related to stock-based compensation									9,000	4,800	1,600
Dividends paid to stockholders									(11,500)	(7,700)	(7,600)
Payments on notes payable and capital leases									0	(60,000)	(10,000)
Excess tax benefits from stock-based compensation									0	1,200	1,200
Net cash used in financing activities									(23,600)	(61,700)	(14,800)
Net increase (decrease) in cash and cash equivalents									40,000	(9,500)	4,500
Cash and cash equivalents at the beginning of the period				$ 1,400				$ 10,900	1,400	10,900	6,400
Cash and cash equivalents at the end of the period	$ 41,400				$ 1,400				$ 41,400	$ 1,400	$ 10,900

Schedule VI. Supplemental Inf88

Schedule VI. Supplemental Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
Deferred policy acquisition costs	$ 44,300				$ 44,300				$ 44,300	$ 44,300	$ 44,600
Unpaid losses and loss adjustment expenses	2,301,000				2,347,500				2,301,000	2,347,500	2,369,700	$ 2,330,500
Unearned premiums	310,300				308,900				310,300	308,900	310,800
Net premiums earned	$ 172,000	$ 173,300	$ 176,900	$ 172,600	$ 181,800	$ 179,000	$ 170,600	$ 159,000	694,800	690,400	684,500
Net investment income									73,200	72,200	72,400
Current year									452,900	456,900	503,800
Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense Including LPT Amortization and Adj									(35,000)	(27,600)	(50,400)
Deferred policy acquisition cost, amortization expense									104,500	103,900	102,700
Payments For Losses And Loss Adjustment Expense Including LPT Amortization and Adj									416,200	410,200	340,600
Premiums written, net									$ 694,600	$ 689,300	$ 687,600