ProAssurance (PRA) 10-Q 4 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	PROASSURANCE CORP
Entity Central Index Key	1,127,703
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Amendment Flag	false
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		53,396,308

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Investments
Fixed maturities, available for sale, at fair value; amortized cost, $2,573,272 and $2,586,821, respectively	$ 2,604,429	$ 2,613,406
Equity securities, trading, at fair value; cost, $354,077 and $353,744, respectively	391,206	387,274
Short-term investments	280,341	442,084
Business owned life insurance	60,589	60,134
Investment in unconsolidated subsidiaries	330,479	340,906
Other investments, $29,978 and $31,501 at fair value, respectively, otherwise at cost or amortized cost	80,576	81,892
Total Investments	3,747,620	3,925,696
Cash and cash equivalents	101,918	117,347
Premiums receivable	224,718	223,480
Receivable from reinsurers on paid losses and loss adjustment expenses	5,574	5,446
Receivable from reinsurers on unpaid losses and loss adjustment expenses	271,679	273,475
Prepaid reinsurance premiums	43,184	39,723
Deferred policy acquisition costs	49,185	46,809
Deferred tax asset, net	1,870	10,256
Real estate, net	31,580	31,814
Intangible assets	82,999	84,406
Goodwill	210,725	210,725
Other assets	101,589	96,004
Total Assets	4,872,641	5,065,181
Policy liabilities and accruals
Reserve for losses and loss adjustment expenses	1,996,989	1,993,428
Unearned premiums	397,139	372,563
Reinsurance premiums payable	34,222	30,001
Total Policy Liabilities	2,428,350	2,395,992
Other liabilities	170,317	422,285
Debt less debt issuance costs	448,288	448,202
Total Liabilities	3,046,955	3,266,479
Shareholders’ Equity
Common shares, par value $0.01 per share, 100,000,000 shares authorized, 62,805,233 and 62,660,234 shares issued, respectively	628	627
Additional paid-in capital	375,912	376,518
Accumulated other comprehensive income (loss), net of deferred tax expense (benefit) of $11,375 and $9,894, respectively	20,323	17,399
Retained earnings	1,848,751	1,824,088
Treasury shares, at cost, 9,408,825 shares and 9,408,977 shares, respectively	(419,928)	(419,930)
Total Shareholders’ Equity	1,825,686	1,798,702
Total Liabilities and Shareholders’ Equity	$ 4,872,641	$ 5,065,181

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Fixed maturities, available for sale, at fair value; amortized cost	$ 2,573,272	$ 2,586,821
Equity securities, trading, cost	354,077	353,744
Other investments, portion carried at fair value	$ 29,978	$ 31,501
Common shares, par value (USD per share)	$ 0.01	$ 0.01
Common shares, shares authorized	100,000,000	100,000,000
Common shares, shares issued	62,805,233	62,660,234
Deferred tax expense (benefit) on accumulated other comprehensive income (loss)	$ 11,375	$ 9,894
Treasury shares, number of shares	9,408,925	9,408,977

Condensed Consolidated Statemen

Condensed Consolidated Statements of Changes in Capital (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase (Decrease) in Stockholders' Equity:
Beginning Balance	$ 1,798,702	$ 1,958,354
Common shares reacquired	0	(1,301)
Common shares issued for compensation and effect of shares reissued to stock purchase plan	940	1,509
Share-based compensation	3,346	2,715
Net effect of restricted and performance shares issued and stock options exercised	(5,314)	(2,895)
Dividends to shareholders	(16,516)	(16,445)
Other comprehensive income (loss)	2,924	23,260
Net income	41,455	19,317
Ending Balance	1,825,686	1,984,514
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity:
Beginning Balance	627	625
Net effect of restricted and performance shares issued and stock options exercised	1	1
Ending Balance	628	626
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity:
Beginning Balance	376,518	365,399
Common shares issued for compensation and effect of shares reissued to stock purchase plan	938	1,509
Share-based compensation	3,346	2,715
Net effect of restricted and performance shares issued and stock options exercised	(5,315)	(2,896)
Ending Balance	375,912	366,727
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity:
Beginning Balance	17,399	23,855
Other comprehensive income (loss)	2,924	23,260
Ending Balance	20,323	47,115
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity:
Beginning Balance	1,824,088	1,988,035
Dividends to shareholders	(16,516)	(16,445)
Net income	41,455	19,317
Ending Balance	1,848,751	1,990,907
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity:
Beginning Balance	419,930	(419,560)
Common shares reacquired	0	(1,301)
Common shares issued for compensation and effect of shares reissued to stock purchase plan	2	0
Ending Balance	$ (419,928)	$ (420,861)

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Income and Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues
Net premiums earned	$ 182,903	$ 177,579
Net investment income	23,186	25,440
Equity in earnings (loss) of unconsolidated subsidiaries	1,808	(3,634)
Net realized investment gains (losses):
OTTI losses	(419)	(10,734)
Portion of OTTI losses recognized in other comprehensive income before taxes	248	1,068
Net impairment losses recognized in earnings	(171)	(9,666)
Other net realized investment gains (losses)	13,451	1,314
Total net realized investment gains (losses)	13,280	(8,352)
Other income	1,821	2,354
Total revenues	222,998	193,387
Expenses
Net losses and loss adjustment expenses	119,151	110,955
Underwriting, policy acquisition and operating expenses	57,108	56,889
Segregated portfolio cells dividend expense (income)	2,375	1,176
Interest expense	4,133	3,686
Total expenses	182,767	172,706
Income before income taxes	40,231	20,681
Provision for income taxes
Current expense (benefit)	(8,278)	(651)
Deferred expense (benefit)	7,054	2,015
Total income tax expense (benefit)	(1,224)	1,364
Net income	41,455	19,317
Other comprehensive income (loss), after tax, net of reclassification adjustments	2,924	23,260
Comprehensive income	$ 44,379	$ 42,577
Earnings per share:
Basic (USD per share)	$ 0.78	$ 0.36
Diluted (USD per share)	$ 0.77	$ 0.36
Weighted average number of common shares outstanding:
Basic (in shares)	53,315	53,157
Diluted (in shares)	53,535	53,346
Cash dividends declared per common share (USD per share)	$ 0.31	$ 0.31

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Activities
Net income	$ 41,455	$ 19,317
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization, net of accretion	7,803	8,630
(Increase) decrease in cash surrender value of BOLI	(455)	(460)
Net realized investment (gains) losses	(13,280)	8,352
Share-based compensation	3,346	2,715
Deferred income taxes	7,054	2,015
Policy acquisition costs, net amortization (net deferral)	(2,376)	(570)
Equity in (earnings) loss of unconsolidated subsidiaries	(1,808)	3,634
Other	(167)	971
Other changes in assets and liabilities:
Premiums receivable	(1,238)	(2,849)
Reinsurance related assets and liabilities	2,428	(11,679)
Other assets	(5,027)	15,782
Reserve for losses and loss adjustment expenses	3,561	444
Unearned premiums	24,576	25,019
Other liabilities	(7,393)	(14,339)
Net cash provided (used) by operating activities	58,479	56,982
Purchases of:
Fixed maturities, available for sale	(160,364)	(199,590)
Equity securities, trading	(35,400)	(23,746)
Other investments	(3,930)	(9,623)
Funding of qualified affordable housing tax credit limited partnerships	(37)	(702)
Investment in unconsolidated subsidiaries	(5,613)	(20,581)
Proceeds from sales or maturities of:
Fixed maturities, available for sale	171,986	225,897
Equity securities, trading	41,584	20,496
Other investments	6,788	4,830
Distributions from unconsolidated subsidiaries	17,848	1,643
Net sales or maturities (purchases) of short-term investments	160,792	(29,130)
Unsettled security transactions, net change	6,296	(229)
Purchases of capital assets	(4,535)	0
Other	1,159	(1,100)
Net cash provided (used) by investing activities	196,574	(31,835)
Financing Activities
Repurchase of common stock	0	(1,301)
Dividends to shareholders	(265,664)	(69,438)
External capital contribution received for segregated portfolio cells	114	4,336
Other	(4,932)	(2,532)
Net cash provided (used) by financing activities	(270,482)	(68,935)
Increase (decrease) in Cash and cash equivalents	(15,429)	(43,788)
Cash and cash equivalents at beginning of period	117,347	241,100
Cash and cash equivalents at end of period	101,918	197,312
Significant non-cash transactions
Dividends declared and not yet paid	$ 16,516	$ 16,445

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements include the accounts of ProAssurance Corporation and its consolidated subsidiaries (ProAssurance, PRA or the Company). The financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation, consisting of normal recurring adjustments, have been included. ProAssurance’s results for the three months ended March 31, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 . The accompanying Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and Notes contained in ProAssurance’s December 31, 2016 report on Form 10-K. In connection with its preparation of the Condensed Consolidated Financial Statements, ProAssurance evaluated events that occurred subsequent to March 31, 2017 for recognition or disclosure in its financial statements and notes to financial statements. ProAssurance operates in four reportable segments as follows: Specialty P&C , Workers' Compensation, Lloyd's Syndicate and Corporate. For more information on the nature of products and services provided and for financial information by segment, refer to Note 12 of the Notes to Condensed Consolidated Financial Statements. Other Liabilities Other liabilities consisted of the following: (In millions) March 31, 2017 December 31, 2016 SPC dividends payable $ 37.0 $ 34.3 Unpaid dividends 16.5 265.7 All other 116.8 122.3 Total other liabilities $ 170.3 $ 422.3 SPC dividends payable are the cumulative undistributed earnings contractually payable to the external preferred shareholders of SPC s operated by ProAssurance's Cayman Islands subsidiary, Eastern Re . Unpaid dividends represent common stock dividends declared by ProAssurance's Board of Directors that had not yet been paid. Unpaid dividends at December 31, 2016 reflect a special dividend declared in late 2016 that was paid in January 2017 . Accounting Changes Adopted Improvements to Employee Share-Based Payment Accounting Effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years, the FASB issued guidance that simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of cash flows, and the classification of awards as either equity or liabilities. Under the new guidance, the difference between the deduction for tax purposes and the compensation cost recognized for financial reporting purposes is to be recognized as income tax expense in the current period and included with other income tax cash flows as an operating activity. The threshold for equity classification has also been revised to permit withholdings up to the maximum statutory tax rates in the applicable jurisdictions. The update also provides an accounting policy election to account for forfeitures as they occur. ProAssurance adopted the guidance as of January 1, 2017. The primary effects of the adoption on the current period are the following: (1) using a prospective application, ProAssurance recorded unrecognized excess tax benefits of $2.3 million as a current tax expense, (2) using a modified retrospective application, ProAssurance elected to recognize forfeitures as they occur and recorded a $0.4 million increase to Additional paid-in capital and a respective $0.3 million reduction to Retained earnings and a $0.1 million increase to deferred taxes to reflect the incremental share-based compensation expense, net of related tax impacts, that would have been recognized in prior years under the modified guidance and (3) excess tax benefits from share-based compensation of $2.3 million was reclassified from financing activities to operating activities in the Condensed Consolidated Statements of Cash Flows. Interests Held Through Related Parties that are Under Common Control Effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years, the FASB issued additional guidance regarding consolidation of legal entities such as limited partnerships, limited liability corporations, and securitization structures (collateralized debt obligations, collateralized loan obligations, and mortgage-backed security transactions). The new guidance modifies the criteria used by a reporting entity when determining if it is a primary beneficiary of a VIE when there are entities under common control and the reporting entity has indirect interests in the VIE through related party relationships. ProAssurance adopted the guidance as of January 1, 2017. Adoption of the guidance had no material effect on ProAssurance’s results of operations or financial position. Simplifying the Transition to the Equity Method of Accounting Effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years, the FASB issued guidance that eliminates the requirement for retroactive restatement when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence. The new guidance provides that the cost of acquiring an additional interest in an investee is to be added to the current basis of an investor’s previously held interest and the equity method of accounting adopted as of the date the investment becomes qualified for equity method accounting with no retroactive adjustment of the investment. If an available-for-sale equity security qualifies for the equity method of accounting the unrealized holding gain or loss in accumulated other comprehensive income is to be recognized through earnings at the date the investment becomes qualified for use of the equity method. ProAssurance adopted the guidance as of January 1, 2017. Adoption of the guidance had no material effect on ProAssurance’s results of operations or financial position. Accounting Changes Not Yet Adopted Clarifying the Definition of a Business Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance which provides clarification of the definition of a business, affecting areas such as acquisitions, disposals, goodwill and consolidation. The new guidance intends to assist entities with determining whether a transaction should be accounted for as an acquisition or disposal of assets or a business. ProAssurance plans to adopt the guidance beginning January 1, 2018. Adoption is not expected to have a material effect on ProAssurance’s results of operations or financial position. Restricted Cash Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance related to the classification of restricted cash presented in the statement of cash flows with the objective of reducing diversity in practice. Under the new guidance, entities are required to include restricted cash and restricted cash equivalents with cash and cash equivalents when reconciling beginning-of-period and end-of-period total amounts as presented on the statement of cash flows. ProAssurance plans to adopt the guidance beginning January 1, 2018. Adoption is not expected to have a material effect on ProAssurance’s results of operations or financial position as it affects disclosure only. Intra-Entity Transfers of Assets Other than Inventory Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance which reduces the complexity in accounting standards related to the income tax consequences of intra-entity transfers of assets other than inventory. Under the new guidance, entities are required to recognize income tax consequences of an intra-entity transfer of assets other than inventory when the transfer occurs instead of delaying recognition until the asset has been sold to an outside party. ProAssurance is in the process of evaluating the effect the new guidance would have on its results of operations and financial position and plans to adopt the guidance beginning January 1, 2018. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position. Classification of Certain Cash Receipts and Cash Payments Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance related to the classification of certain cash receipts and cash payments presented in the statement of cash flows with the objective of reducing diversity in practice. ProAssurance plans to adopt the guidance beginning January 1, 2018. Adoption is not expected to have a material effect on ProAssurance’s results of operations or financial position as it affects disclosure only. Revenue from Contracts with Customers Effective for fiscal years beginning after December 15, 2017 the FASB issued guidance related to revenue from contracts with customers. The core principle of the new guidance is that revenue is recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ProAssurance plans to adopt the guidance beginning January 1, 2018. As the majority of ProAssurance's revenues come from insurance contracts which fall under the scope of other FASB standards, adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position. Recognition and Measurement of Financial Assets and Financial Liabilities Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance that requires equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. The new guidance also specifies that an entity use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and present financial assets and liabilities by measurement category and form of financial asset. Other provisions of the new guidance include: revised disclosure requirements related to the presentation in comprehensive income of changes in the fair value of liabilities; elimination, for public companies, of disclosure requirements relative to the method(s) and significant assumptions underlying fair values disclosed for financial instruments measured at amortized cost; and simplified impairment assessments for equity investments without readily determinable fair values. ProAssurance plans to adopt the guidance beginning January 1, 2018. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position. Premium Amortization on Purchased Callable Debt Securities Effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, the FASB issued guidance that will require the premium for certain callable debt securities to be amortized over a shorter period than is currently required. Currently amortization is permitted over the contractual life of the instrument and the guidance shortens the amortization to the earliest call date. The purpose of the guidance is to more closely align the amortization period of premiums to expectations incorporated in market pricing on the underlying securities. ProAssurance plans to adopt the guidance beginning January 1, 2019. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position. Leases Effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, the FASB issued guidance that requires a lessee to recognize for all leases (with the exception of short-term leases) a lease liability, which is a lessee's obligation to make lease payments arising from a lease, measured on a discounted basis, and a right-of-use asset, which is an asset that represents the lessee's right to use, or control the use of, a specified asset for the lease term. ProAssurance plans to adopt the guidance beginning January 1, 2019. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position as ProAssurance does not have any leases it believes to be material. Simplifying the Test for Goodwill Impairment Effective for the fiscal years beginning after December 15, 2019 and interim periods within those fiscal years, the FASB issued guidance that simplifies the requirements to test goodwill for impairment for business entities that have goodwill reported in their financial statements. The guidance eliminates the second step of the impairment test which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount. In addition, the guidance also eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment. ProAssurance plans to adopt the guidance beginning January 1, 2020. Adoption is not expected to have a material effect on ProAssurance’s results of operations or financial position. Improvements to Financial Instruments - Credit Losses Effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years, the FASB issued guidance that replaces the incurred loss impairment methodology, which delays recognition of credit losses until a probable loss has been incurred, with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Under the new guidance, credit losses are required to be recorded through an allowance for credit losses account and the income statement reflects the measurement for newly recognized financial assets, as well as increases or decreases of expected credit losses that have taken place during the period. ProAssurance is in the process of evaluating the effect the new guidance would have on its results of operations and financial position and plans to adopt the guidance beginning January 1, 2020. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position.

Fair Value Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three level hierarchy has been established for valuing assets and liabilities based on how transparent (observable) the inputs are that are used to determine fair value, with the inputs considered most observable categorized as Level 1 and those that are the least observable categorized as Level 3. Hierarchy levels are defined as follows: Level 1: quoted (unadjusted) market prices in active markets for identical assets and liabilities. For ProAssurance, Level 1 inputs are generally quotes for debt or equity securities actively traded in exchange or over-the-counter markets. Level 2: market data obtained from sources independent of the reporting entity (observable inputs). For ProAssurance, Level 2 inputs generally include quoted prices in markets that are not active, quoted prices for similar assets or liabilities, and results from pricing models that use observable inputs such as interest rates and yield curves that are generally available at commonly quoted intervals. Level 3: the reporting entity's own assumptions about market participant assumptions based on the best information available in the circumstances (non-observable inputs). For ProAssurance, Level 3 inputs are used in situations where little or no Level 1 or 2 inputs are available or are inappropriate given the particular circumstances. Level 3 inputs include results from pricing models for which some or all of the inputs are not observable, discounted cash flow methodologies, single non-binding broker quotes and adjustments to externally quoted prices that are based on management judgment or estimation. Fair values of assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 are shown in the following tables. Where applicable, the tables also indicate the fair value hierarchy of the valuation techniques utilized to determine those fair values. For some assets, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. When this is the case, the asset is categorized based on the level of the most significant input to the fair value measurement. Assessments of the significance of a particular input to the fair value measurement require judgment and consideration of factors specific to the assets being valued. March 31, 2017 Fair Value Measurements Using Total (In thousands) Level 1 Level 2 Level 3 Fair Value Assets: Fixed maturities, available for sale U.S. Treasury obligations $ — $ 148,211 $ — $ 148,211 U.S. Government-sponsored enterprise obligations — 28,701 — 28,701 State and municipal bonds — 770,061 — 770,061 Corporate debt, multiple observable inputs 2,395 1,284,664 — 1,287,059 Corporate debt, limited observable inputs — — 18,914 18,914 Residential mortgage-backed securities — 207,906 — 207,906 Agency commercial mortgage-backed securities — 12,688 — 12,688 Other commercial mortgage-backed securities — 19,697 — 19,697 Other asset-backed securities — 108,190 3,002 111,192 Equity securities Financial 84,052 — — 84,052 Utilities/Energy 51,304 — — 51,304 Consumer oriented 60,686 — — 60,686 Industrial 52,497 — — 52,497 Bond funds 92,753 — — 92,753 All other 49,914 — — 49,914 Short-term investments 277,494 2,847 — 280,341 Other investments 1,270 27,805 903 29,978 Total assets categorized within the fair value hierarchy $ 672,365 $ 2,610,770 $ 22,819 3,305,954 LP/LLC interests carried at NAV which approximates fair value. These interests, reported as a part of Investment in unconsolidated subsidiaries, are not categorized within the fair value hierarchy. 199,696 Total assets at fair value $ 3,505,650 December 31, 2016 Fair Value Measurements Using Total (In thousands) Level 1 Level 2 Level 3 Fair Value Assets: Fixed maturities, available for sale U.S. Treasury obligations $ — $ 146,539 $ — $ 146,539 U.S. Government-sponsored enterprise obligations — 30,235 — 30,235 State and municipal bonds — 800,463 — 800,463 Corporate debt, multiple observable inputs 2,339 1,261,842 — 1,264,181 Corporate debt, limited observable inputs — — 14,810 14,810 Residential mortgage-backed securities — 217,906 — 217,906 Agency commercial mortgage-backed securities — 12,783 — 12,783 Other commercial mortgage-backed securities — 19,611 — 19,611 Other asset-backed securities — 103,871 3,007 106,878 Equity securities Financial 81,749 — — 81,749 Utilities/Energy 52,869 — — 52,869 Consumer oriented 61,284 — — 61,284 Industrial 54,265 — — 54,265 Bond funds 79,843 10,159 — 90,002 All other 27,181 19,924 — 47,105 Short-term investments 437,580 4,504 — 442,084 Other investments 1,956 29,542 3 31,501 Total assets categorized within the fair value hierarchy $ 799,066 $ 2,657,379 $ 17,820 3,474,265 LP/LLC interests carried at NAV which approximates fair value. These interests, reported as a part of Investment in unconsolidated subsidiaries, are not categorized within the fair value hierarchy. 204,719 Total assets at fair value $ 3,678,984 The fair values for securities included in the Level 2 category, with the few exceptions described below, were developed by one of several third party, nationally recognized pricing services, including services that price only certain types of securities. Each service uses complex methodologies to determine values for securities and subject the values they develop to quality control reviews. Management selected a primary source for each type of security in the portfolio and reviewed the values provided for reasonableness by comparing data to alternate pricing services and to available market and trade data. Values that appeared inconsistent were further reviewed for appropriateness. Any value that did not appear reasonable was discussed with the service that provided the value and adjusted, if necessary. No such adjustments were made during 2017 . One nominal adjustment was made during 2016 and related to an investment in an unrealized loss position that was subsequently sold during 2016. Level 2 Valuations Below is a summary description of the valuation methodologies primarily used by the pricing services for securities in the Level 2 category, by security type: U.S. Treasury obligations were valued based on quoted prices for identical assets, or, in markets that are not active, quotes for similar assets, taking into consideration adjustments for variations in contractual cash flows and yields to maturity. U.S. Government-sponsored enterprise obligations were valued using pricing models that consider current and historical market data, normal trading conventions, credit ratings, and the particular structure and characteristics of the security being valued, such as yield to maturity, redemption options, and contractual cash flows. Adjustments to model inputs or model results were included in the valuation process when necessary to reflect recent regulatory, government or corporate actions or significant economic, industry or geographic events affecting the security’s fair value. State and municipal bonds were valued using a series of matrices that considered credit ratings, the structure of the security, the sector in which the security falls, yields, and contractual cash flows. Valuations were further adjusted, when necessary, to reflect the expected effect on fair value of recent significant economic or geographic events or ratings changes. Corporate debt, multiple observable inputs consisted primarily of corporate bonds, but also included a small number of bank loans. The methodology used to value Level 2 corporate bonds was the same as the methodology previously described for U.S. Government-sponsored enterprise obligations. Bank loans were valued based on an average of broker quotes for the loans in question, if available. If quotes were not available, the loans were valued based on quoted prices for comparable loans or, if the loan was newly issued, by comparison to similar seasoned issues. Broker quotes were compared to actual trade prices to permit assessment of the reliability of the quotes; unreliable quotes were not considered in quoted averages. Residential and commercial mortgage-backed securities were valued using a pricing matrix which considers the issuer type, coupon rate and longest cash flows outstanding. The matrix used was based on the most recently available market information. Agency and non-agency collateralized mortgage obligations were both valued using models that consider the structure of the security, current and historical information regarding prepayment speeds, ratings and ratings updates, and current and historical interest rate and interest rate spread data. Other asset-backed securities were valued using models that consider the structure of the security, monthly payment information, current and historical information regarding prepayment speeds, ratings and ratings updates, and current and historical interest rate and interest rate spread data. Spreads and prepayment speeds consider collateral type. Equity securities were securities not traded on an exchange on the valuation date. The securities were valued using the most recently available quotes for the securities. Short-term investments are securities maturing within one year, carried at cost which approximated the fair value of the security due to the short term to maturity. Other investments consisted primarily of convertible bonds valued using a pricing model that incorporated selected dealer quotes as well as current market data regarding equity prices and risk free rates. If dealer quotes were unavailable for the security being valued, quotes for securities with similar terms and credit status were used in the pricing model. Dealer quotes selected for use were those considered most accurate based on parameters such as underwriter status and historical reliability. Level 3 Valuations Below is a summary description of the valuation processes and methodologies used as well as quantitative information regarding securities in the Level 3 category. Level 3 Valuation Processes • Level 3 securities are priced by the Chief Investment Officer. • Level 3 valuations are computed quarterly. Prices are evaluated quarterly against prior period prices and the expected change in prices. • ProAssurance Level 3 securities are primarily NRSRO rated debt instruments for which comparable market inputs are commonly available for evaluating the securities in question. Valuation of these debt instruments is not overly sensitive to changes in the unobservable inputs used. Level 3 Valuation Methodologies Corporate debt, limited observable inputs consisted of corporate bonds valued using dealer quotes for similar securities or discounted cash flow models using yields currently available for similar securities. Similar securities are defined as securities of comparable credit quality that have like terms and payment features. Assessments of credit quality were based on NRSRO ratings, if available, or were subjectively determined by management if not available. At March 31, 2017 , 88% of the securities were rated; the average rating was BBB . At December 31, 2016 , 84% of the securities were rated; the average rating was BBB+ . Other asset-backed securities consisted of securitizations of receivables valued using dealer quotes for similar securities or discounted cash flow models using yields currently available for similar securities. Other investments consisted of convertible securities for which limited observable inputs were available at March 31, 2017 and at December 31, 2016 . The securities were valued internally based on expected cash flows, including the expected final recovery, discounted at a yield that considered the lack of liquidity and the financial status of the issuer. Quantitative Information Regarding Level 3 Valuations Fair Value at (In thousands) March 31, 2017 December 31, 2016 Valuation Technique Unobservable Input Range Assets: Corporate debt, limited observable inputs $18,914 $14,810 Market Comparable Comparability Adjustment 0% - 5% (2.5%) Discounted Cash Flows Comparability Adjustment 0% - 5% (2.5%) Other asset-backed securities $3,002 $3,007 Market Comparable Comparability Adjustment 0% - 5% (2.5%) Discounted Cash Flows Comparability Adjustment 0% - 5% (2.5%) Other investments $903 $3 Discounted Cash Flows Comparability Adjustment 0% - 10% (5%) The significant unobservable inputs used in the fair value measurement of the above listed securities were the valuations of comparable securities with similar issuers, credit quality and maturity. Changes in the availability of comparable securities could result in changes in the fair value measurements. Fair Value Measurements - Level 3 Assets The following tables (the Level 3 Tables) present summary information regarding changes in the fair value of assets measured at fair value using Level 3 inputs. March 31, 2017 Level 3 Fair Value Measurements – Assets (In thousands) Corporate Debt Asset-backed Securities All other investments Total Balance December 31, 2016 $ 14,810 $ 3,007 $ 3 $ 17,820 Total gains (losses) realized and unrealized: Included in earnings, as a part of: Net investment income (39 ) — — (39 ) Net realized investment gains (losses) 13 — — 13 Included in other comprehensive income (208 ) (5 ) 2 (211 ) Purchases 7,048 — — 7,048 Sales (1,712 ) — — (1,712 ) Transfers in — — 898 898 Transfers out (998 ) — — (998 ) Balance March 31, 2017 $ 18,914 $ 3,002 $ 903 $ 22,819 Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end $ — $ — $ — $ — March 31, 2016 Level 3 Fair Value Measurements – Assets (In thousands) Corporate Debt Asset-backed Securities All other investments Total Balance December 31, 2015 $ 14,500 $ 757 $ — $ 15,257 Total gains (losses) realized and unrealized: Included in earnings, as a part of: Net investment income (14 ) — (1 ) (15 ) Net realized investment gains (losses) (75 ) — — (75 ) Included in other comprehensive income (75 ) (2 ) (1 ) (78 ) Purchases — 3,500 1,560 5,060 Sales (681 ) (167 ) — (848 ) Transfers in — — — — Transfers out (6 ) — — (6 ) Balance March 31, 2016 $ 13,649 $ 4,088 $ 1,558 $ 19,295 Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end $ — $ — $ — $ — Transfers Equity securities of approximately $35.4 million were transferred from Level 2 to Level 1 during the three months ended March 31, 2017 . There were no transfers between the Level 1 and Level 2 categories during the same period of 2016 . Transfers shown in the preceding Level 3 tables were as of the end of the quarter in which the transfer occurred. All transfers were to or from Level 2. All transfers during the three months ended March 31, 2017 and 2016 related to securities held for which the level of market activity for identical or nearly identical securities varies from period to period. The securities were valued using multiple observable inputs when those inputs were available; otherwise the securities were valued using limited observable inputs. Fair Values Not Categorized Investments in unconsolidated subsidiaries at both March 31, 2017 and December 31, 2016 included interests in investment fund LP s/ LLC s that measure fund assets at fair value on a recurring basis and that provide a NAV for the interest. The carrying value of these interests is based on the NAV provided and was considered to approximate the fair value of the interests. In accordance with GAAP , the fair value of these investments was not classified within the fair value hierarchy. Additional information regarding these investments is as follows: Unfunded Fair Value (In thousands) March 31, March 31, December 31, Investments in LPs/LLCs: Private debt funds (1) $11,972 $ 51,307 $ 55,637 Long equity fund (2) None 6,770 6,268 Long/short equity funds (3) None 29,944 28,926 Non-public equity funds (4) $55,334 86,506 89,691 Multi-strategy fund of funds (5) None 8,668 8,448 Structured credit fund (6) None 4,466 4,273 Long/short commodities fund (7) None 12,035 11,476 $ 199,696 $ 204,719 (1) The investment is comprised of interests in two unrelated LP funds that are structured to provide interest distributions primarily through diversified portfolios of private debt instruments. One LP allows redemption by special consent; the other does not permit redemption. Income and capital are to be periodically distributed at the discretion of the LP s over an anticipated time frame that spans from three to eight years. (2) The fund is a LP that holds long equities of public international companies. Redemptions are allowed at the end of any calendar month with a prior notice requirement of 15 days and are paid within 10 days of the end of the calendar month of the redemption request. (3) The investment is comprised of interests in multiple unrelated LP funds. The funds hold primarily long and short North American equities and target absolute returns using strategies designed to take advantage of market opportunities. The funds generally permit quarterly or semi-annual capital redemptions subject to notice requirements of 30 to 90 days. For some funds, redemptions above specified thresholds (lowest threshold is 90% ) may be only partially payable until after a fund audit is completed and are then payable within 30 days. (4) The investment is comprised of interests in multiple unrelated LP funds, each structured to provide capital appreciation through diversified investments in private equity, which can include investments in buyout, venture capital, mezzanine debt, distressed debt, and other private equity-oriented LP s. Two of the LP s allow redemption by terms set forth in the LP agreements; the others do not permit redemption. Income and capital are to be periodically distributed at the discretion of the LP over time frames that are anticipated to span up to nine years. (5) This fund is a LLC structured to build and manage low volatility, multi-manager portfolios that have little or no correlation to the broader fixed income and equity security markets. Redemptions are not permitted but offers to repurchase units of the LLC may be extended periodically. (6) This fund is a LP seeking to obtain superior risk-adjusted absolute returns by acquiring and actively managing a diversified portfolio of debt securities, including bonds, loans and other asset-backed instruments. Redemptions are allowed at any quarter-end with a prior notice requirement of 90 days . (7) This fund is a LLC invested across a broad range of commodities and focuses primarily on market neutral, relative value strategies, seeking to generate absolute returns with low correlation to broad commodity, equity and fixed income markets. Following an initial one year lock-up period, redemptions are allowed with a prior notice requirement of 30 days and are payable within 30 days. ProAssurance may not sell, transfer or assign its interest in any of the above LP s/ LLC s without special consent from the LP s/ LLC s. Financial Instruments - Methodologies Other Than Fair Value The following table provides the estimated fair value of our financial instruments that, in accordance with GAAP for the type of investment, are measured using a methodology other than fair value. All fair values provided fall within the Level 3 fair value category. March 31, 2017 December 31, 2016 (In thousands) Carrying Fair Carrying Fair Financial assets: BOLI $ 60,589 $ 60,589 $ 60,134 $ 60,134 Other investments $ 50,598 $ 62,061 $ 50,391 $ 58,757 Other assets $ 29,196 $ 29,072 $ 29,111 $ 28,960 Financial liabilities: Senior notes due 2023 $ 250,000 $ 274,315 $ 250,000 $ 270,898 Revolving Credit Agreement $ 200,000 $ 200,000 $ 200,000 $ 200,000 Other liabilities $ 17,855 $ 17,855 $ 17,033 $ 17,011 The fair value of the BOLI was equal to the cash surrender value associated with the policies on the valuation date. Other investments listed in the table above include interests in certain investment fund LP s/ LLC s accounted for using the cost method, investments in FHLB common stock carried at cost, and an annuity investment carried at amortized cost. The estimated fair value of the LP / LLC interests was based on the equity value of the interest provided by the LP / LLC managers for the most recent quarter, which approximates the fair value of the interest. The estimated fair value of the FHLB common stock was based on the amount ProAssurance would receive if its membership were canceled, as the membership cannot be sold. The fair value of the annuity represents the present value of the expected future cash flows discounted using a rate available in active markets for similarly structured instruments. Other assets and Other liabilities primarily consisted of related investment assets and liabilities associated with funded deferred compensation agreements. Fair values of the funded deferred compensation assets and liabilities were based on the NAV s provided by the underlying funds. Other assets also included a secured note receivable and unsecured note receivables under two separate line of credit agreements. Fair value of these receivables was based on the present value of expected cash flows from the receivables, discounted at market rates on the valuation date for receivables with similar credit standings and similar payment structures. The fair value of the debt was estimated based on the present value of expected future cash outflows, discounted at rates available on the valuation date for similar debt issued by entities with a similar credit standing to ProAssurance.

Investments

Investments	3 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Available-for-sale securities at March 31, 2017 and December 31, 2016 included the following: March 31, 2017 (In thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Fixed maturities U.S. Treasury obligations $ 147,826 $ 1,203 $ 818 $ 148,211 U.S. Government-sponsored enterprise obligations 28,621 241 161 28,701 State and municipal bonds 755,639 19,139 4,717 770,061 Corporate debt 1,291,140 21,812 6,979 1,305,973 Residential mortgage-backed securities 206,455 3,407 1,956 207,906 Agency commercial mortgage-backed securities 12,727 63 102 12,688 Other commercial mortgage-backed securities 19,650 153 106 19,697 Other asset-backed securities 111,214 191 213 111,192 $ 2,573,272 $ 46,209 $ 15,052 $ 2,604,429 December 31, 2016 (In thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Fixed maturities U.S. Treasury obligations $ 146,186 $ 1,264 $ 911 $ 146,539 U.S. Government-sponsored enterprise obligations 30,038 388 191 30,235 State and municipal bonds 790,154 17,261 6,952 800,463 Corporate debt 1,264,812 22,659 8,480 1,278,991 Residential mortgage-backed securities 216,285 3,667 2,046 217,906 Agency commercial mortgage-backed securities 12,837 89 143 12,783 Other commercial mortgage-backed securities 19,571 177 137 19,611 Other asset-backed securities 106,938 207 267 106,878 $ 2,586,821 $ 45,712 $ 19,127 $ 2,613,406 The recorded cost basis and estimated fair value of available-for-sale fixed maturities at March 31, 2017 , by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (In thousands) Amortized Due in one Due after Due after Due after Total Fair Fixed maturities, available for sale U.S. Treasury obligations $ 147,826 $ 28,876 $ 98,304 $ 18,042 $ 2,989 $ 148,211 U.S. Government-sponsored enterprise obligations 28,621 12,863 7,781 7,918 139 28,701 State and municipal bonds 755,639 66,017 264,597 348,641 90,806 770,061 Corporate debt 1,291,140 122,549 764,626 388,119 30,679 1,305,973 Residential mortgage-backed securities 206,455 207,906 Agency commercial mortgage-backed securities 12,727 12,688 Other commercial mortgage-backed securities 19,650 19,697 Other asset-backed securities 111,214 111,192 $ 2,573,272 $ 2,604,429 Excluding obligations of the U.S. Government or U.S. Government-sponsored enterprises, no investment in any entity or its affiliates exceeded 10% of Shareholders’ equity at March 31, 2017 . Cash and securities with a carrying value of $46.4 million at March 31, 2017 were on deposit with various state insurance departments to meet regulatory requirements. ProAssurance also held securities with a carrying value of $246.5 million at March 31, 2017 that are pledged as collateral security for advances under the Revolving Credit Agreement (see Note 8 of the Notes to Condensed Consolidated Financial Statements for additional detail on the Revolving Credit Agreement ). As a member of Lloyd's and a capital provider to Syndicate 1729 , ProAssurance is required to maintain capital at Lloyd's , referred to as FAL . ProAssurance investments at March 31, 2017 included fixed maturities with a fair value of $96.7 million and short-term investments with a fair value of approximately $1.0 million on deposit with Lloyd's in order to satisfy these FAL requirements. BOLI ProAssurance holds BOLI policies that are carried at the current cash surrender value of the policies (original cost $33 million ). All insured individuals were members of ProAssurance management at the time the policies were acquired. The primary purpose of the program is to offset future employee benefit expenses through earnings on the cash value of the policies. ProAssurance is the owner and beneficiary of these policies. Investment in Unconsolidated Subsidiaries ProAssurance holds investments in unconsolidated subsidiaries, accounted for under the equity method. The investments include the following: Carrying Value (In thousands) March 31, December 31, Investment in LPs/LLCs: Qualified affordable housing tax credit partnerships $ 99,005 $ 102,313 Other tax credit partnerships 11,041 11,459 All other LPs/LLCs 220,433 227,134 $ 330,479 $ 340,906 Qualified affordable housing tax credit partnership interests held by ProAssurance generate investment returns by providing tax benefits to fund investors in the form of tax credits and project operating losses. The carrying value of these investments reflects ProAssurance's total commitments (both funded and unfunded) to the partnerships. ProAssurance's ownership percentage relative to two of the tax credit partnership interests is almost 100% ; these interests had a carrying value of $38.3 million at March 31, 2017 and $40.2 million at December 31, 2016 . ProAssurance's ownership percentage relative to the remaining tax credit partnership interests is less than 20% ; these interests had a carrying value of $60.7 million at March 31, 2017 and $62.1 million at December 31, 2016 . ProAssurance does not have the ability to exert control over the partnerships; all are accounted for using the equity method. Other tax credit partnerships are comprised entirely of historic tax credits. The historic tax credits generate investment returns by providing benefits to fund investors in the form of tax credits, tax deductible project operating losses and positive cash flows. ProAssurance's ownership percentage relative to the tax credit partnerships is almost 100% . ProAssurance does not have the ability to exert control over the partnerships; the interests are accounted for using the equity method. As discussed in additional detail in Note 2 of the Notes to Condensed Consolidated Financial Statements, ProAssurance holds interests in certain LP s/ LLC s that are investment funds which measure fund assets at fair value on a recurring basis and the fund managers provide a NAV for the interest. The carrying value of these interests is based on the NAV provided, and is considered to approximate the fair value of the interests; such interests totaled $199.7 million at March 31, 2017 and $204.7 million at December 31, 2016 . ProAssurance also holds interests in other LP s/ LLC s which are not considered to be investment funds; such interests totaled $20.7 million at March 31, 2017 and $22.4 million at December 31, 2016 . ProAssurance's ownership percentage relative to three of the LP s/ LLC s is greater than 25% , which is expected to be reduced as the funds mature and other investors participate in the funds; these investments had a carrying value of $20.8 million at March 31, 2017 and $18.5 million at December 31, 2016 . ProAssurance's ownership percentage relative to the remaining LP s/ LLC s is less than 25%; these interests had a carrying value of $199.6 million at March 31, 2017 and $208.6 million at December 31, 2016 . ProAssurance does not have the ability to exert control over any of these funds. Other Investments Other investments at March 31, 2017 and December 31, 2016 were comprised as follows: (In thousands) March 31, December 31, Investments in LPs/LLCs, at cost $ 47,164 $ 46,852 Convertible securities, at fair value 29,978 31,501 Other, principally FHLB capital stock, at cost 3,434 3,539 $ 80,576 $ 81,892 Investments in convertible securities are carried at fair value as permitted by the accounting guidance for hybrid financial instruments, with changes in fair value recognized in income as a component of Net realized investment gains (losses) during the period of change. FHLB capital stock is not marketable, but may be liquidated by terminating membership in the FHLB . The liquidation process can take up to five years . Investments Held in a Loss Position The following tables provide summarized information with respect to investments held in an unrealized loss position at March 31, 2017 and December 31, 2016 , including the length of time the investment had been held in a continuous unrealized loss position. March 31, 2017 Total Less than 12 months 12 months or longer Fair Unrealized Fair Unrealized Fair Unrealized (In thousands) Value Loss Value Loss Value Loss Fixed maturities, available for sale U.S. Treasury obligations $ 82,630 $ 818 $ 82,630 $ 818 $ — $ — U.S. Government-sponsored enterprise obligations 10,507 161 10,507 161 — — State and municipal bonds 167,434 4,717 160,343 4,132 7,091 585 Corporate debt 416,640 6,979 382,246 4,361 34,394 2,618 Residential mortgage-backed securities 97,495 1,956 95,381 1,922 2,114 34 Agency commercial mortgage-backed securities 4,571 102 4,191 72 380 30 Other commercial mortgage-backed securities 10,890 106 9,075 85 1,815 21 Other asset-backed securities 46,008 213 42,018 207 3,990 6 $ 836,175 $ 15,052 $ 786,391 $ 11,758 $ 49,784 $ 3,294 December 31, 2016 Total Less than 12 months 12 months or longer Fair Unrealized Fair Unrealized Fair Unrealized (In thousands) Value Loss Value Loss Value Loss Fixed maturities, available for sale U.S. Treasury obligations $ 79,833 $ 911 $ 79,833 $ 911 $ — $ — U.S. Government-sponsored enterprise obligations 11,746 191 11,746 191 — — State and municipal bonds 224,884 6,952 219,276 6,444 5,608 508 Corporate debt 469,632 8,480 424,721 5,662 44,911 2,818 Residential mortgage-backed securities 103,680 2,046 100,542 1,982 3,138 64 Agency commercial mortgage-backed securities 4,579 143 4,192 114 387 29 Other commercial mortgage-backed securities 9,822 137 9,179 134 643 3 Other asset-backed securities 44,343 267 39,079 256 5,264 11 $ 948,519 $ 19,127 $ 888,568 $ 15,694 $ 59,951 $ 3,433 As of March 31, 2017 , excluding U.S. Government or U.S. Government-sponsored enterprise obligations, there were 587 debt securities ( 23.2% of all available-for-sale fixed maturity securities held) in an unrealized loss position representing 397 issuers. The greatest and second greatest unrealized loss positions among those securities were approximately $0.5 million and $0.4 million , respectively. The securities were evaluated for impairment as of March 31, 2017 . As of December 31, 2016 , excluding U.S. Government or U.S. Government-sponsored enterprise obligations, there were 703 debt securities ( 27.2% of all available-for-sale fixed maturity securities held) in an unrealized loss position representing 456 issuers. The greatest and second greatest unrealized loss positions among those securities were each approximately $0.5 million . The securities were evaluated for impairment as of December 31, 2016 . Each quarter, ProAssurance performs a detailed analysis for the purpose of assessing whether any of the securities it holds in an unrealized loss position have suffered an OTTI in value. A detailed discussion of the factors considered in the assessment is included in Note 1 of the Notes to Consolidated Financial Statements included in ProAssurance's December 31, 2016 Form 10-K. Fixed maturity securities held in an unrealized loss position at March 31, 2017 , excluding asset-backed securities, have paid all scheduled contractual payments and are expected to continue doing so. Expected future cash flows of asset-backed securities held in an unrealized loss position were estimated as part of the March 31, 2017 impairment evaluation using the most recently available six-month historical performance data for the collateral (loans) underlying the security or, if historical data was not available, sector based assumptions, and equaled or exceeded the current amortized cost basis of the security. Net Investment Income Net investment income by investment category was as follows: Three Months Ended (In thousands) 2017 2016 Fixed maturities $ 20,121 $ 22,575 Equities 3,644 3,643 Short-term and Other investments 801 405 BOLI 455 460 Investment fees and expenses (1,835 ) (1,643 ) Net investment income $ 23,186 $ 25,440 Equity in Earnings (Loss) of Unconsolidated Subsidiaries Equity in earnings (loss) of unconsolidated subsidiaries included losses from qualified affordable housing project tax credit investments and historic tax credit investments. The losses recorded reflect ProAssurance's allocable portion of partnership operating losses. Losses from qualified affordable housing project tax credit investments were $3.3 million and $5.2 million for the 2017 and 2016 three-month period s, respectively, and tax credits recognized related to these investments totaled $4.6 million for both 2017 and 2016 three-month period s. Losses from historic tax credit investments were $0.4 million and $0.2 million and tax credits recognized related to these investments totaled $1.8 million and $2.6 million for the 2017 and 2016 three-month period s, respectively. Tax credits recognized reduced income tax expense in the respective periods. Net Realized Investment Gains (Losses) Realized investment gains and losses are recognized on the first-in, first-out basis. The following table provides detailed information regarding Net realized investment gains (losses): Three Months Ended March 31 (In thousands) 2017 2016 Total OTTI losses: Corporate debt $ (419 ) $ (7,604 ) Other investments — (3,130 ) Portion of OTTI losses recognized in other comprehensive income before taxes: Corporate debt 248 1,068 Net impairment losses recognized in earnings (171 ) (9,666 ) Gross realized gains, available-for-sale securities 1,853 3,185 Gross realized (losses), available-for-sale securities (67 ) (4,647 ) Net realized gains (losses), trading securities 6,562 2,055 Net realized gains (losses), Other investments 1,172 52 Change in unrealized holding gains (losses), trading securities 3,616 733 Change in unrealized holding gains (losses), convertible securities, carried at fair value 313 (66 ) Other 2 2 Net realized investment gains (losses) $ 13,280 $ (8,352 ) During the first quarter of 2017 , ProAssurance recognized OTTI in earnings of $0.2 million and $0.2 million of non-credit OTTI in OCI both of which related to corporate bonds. During the first quarter of 2016 , ProAssurance recognized OTTI in earnings of $6.5 million related to corporate bonds, including credit-related OTTI of $5.5 million related to debt instruments from ten issuers in the energy sector. The fair value of the bonds and the credit quality of the issuers had declined and ProAssurance recognized credit-related OTTI to reduce the amortized cost basis of the bonds to the present value of future cash flows expected to be received from the bonds. ProAssurance also recognized non-credit OTTI in OCI of $0.9 million related to certain of these same bonds, as the fair value of the bonds was less than the present value of the expected future cash flows from the securities. ProAssurance also recognized a $3.1 million OTTI in earnings for the 2016 three-month period related to an investment fund that is accounted for using the cost method (classified as Other investments). The fund is focused on the energy sector and securities held by the fund declined in value during 2016 . An OTTI was recognized to reduce ProAssurance's carrying value of the investment to the NAV reported by the fund. The following table presents a roll forward of cumulative credit losses recorded in earnings related to impaired debt securities for which a portion of the OTTI was recorded in OCI . Three Months Ended March 31 (In thousands) 2017 2016 Balance beginning of period $ 1,158 $ 5,751 Additional credit losses recognized during the period, related to securities for which: No OTTI has been previously recognized 171 2,398 OTTI has been previously recognized — 2,154 Reductions due to: Securities sold during the period (realized) — (3,744 ) Balance March 31 $ 1,329 $ 6,559 Other information regarding sales and purchases of available-for-sale securities is as follows: Three Months Ended March 31 (In millions) 2017 2016 Proceeds from sales (exclusive of maturities and paydowns) $ 79.2 $ 109.9 Purchases $ 160.4 $ 199.6

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes ProAssurance estimates its annual effective tax rate at the end of each quarterly reporting period and uses this estimated rate to record the provision for income taxes in the interim financial statements. The provision for income taxes is different from that which would be obtained by applying the statutory Federal income tax rate to income before taxes primarily because a portion of ProAssurance’s investment income is tax-exempt, and because ProAssurance utilizes tax credit benefits transferred from tax credit partnership investments. Also, in 2017 no U.S. or U.K. tax expense was recognized relative to ProAssurance's pro rata portion of the operating profits of Syndicate 1729 as prior year operating losses were available to offset the profits. In 2016 , no U.K. tax benefit was recognized relative to ProAssurance's pro rata portion of Syndicate 1729 's operating losses as there was no income against which the losses could be offset. ProAssurance had a receivable for Federal and U.K. income taxes of $3.3 million at March 31, 2017 , carried as a part of Other assets and a liability of $5.1 million at December 31, 2016 , carried as a part of Other liabilities. The liability for unrecognized tax benefits was $8.4 million at March 31, 2017 and December 31, 2016 .

Deferred Policy Acquisition Cos

Deferred Policy Acquisition Costs	3 Months Ended
	Mar. 31, 2017
Insurance [Abstract]
Deferred Policy Acquisition Costs	Deferred Policy Acquisition Costs Policy acquisition costs that are primarily and directly related to the successful production of new and renewal insurance contracts, most significantly agent commissions, premium taxes, and underwriting salaries and benefits, are capitalized as policy acquisition costs and amortized to expense, net of ceding commissions earned, as the related premium revenues are earned. Amortization of DPAC was $22.6 million and $21.5 million for the three months ended March 31, 2017 and 2016 , respectively.

Reserve for Losses and Loss Adj

Reserve for Losses and Loss Adjustment Expenses	3 Months Ended
	Mar. 31, 2017
Insurance [Abstract]
Reserve for Losses and Loss Adjustment Expenses	Reserve for Losses and Loss Adjustment Expenses The reserve for losses is established based on estimates of individual claims and actuarially determined estimates of future losses based on ProAssurance’s past loss experience, available industry data and projections as to future claims frequency, severity, inflationary trends and settlement patterns. Estimating the reserve, particularly the reserve appropriate for liability exposures, is a complex process. Claims may be resolved over an extended period of time, often five years or more, and may be subject to litigation. Estimating losses requires ProAssurance to make and revise judgments and assessments regarding multiple uncertainties over an extended period of time. As a result, the reserve estimate may vary considerably from the eventual outcome. The assumptions used in establishing ProAssurance’s reserve are regularly reviewed and updated by management as new data becomes available. Changes to estimates of previously established reserves are included in earnings in the period in which the estimate is changed. ProAssurance believes that the methods it uses to establish reserves are reasonable and appropriate. Each year, ProAssurance uses internal actuaries to review the reserve for losses of each insurance subsidiary. ProAssurance also engages consulting actuaries to review ProAssurance claims data and provide observations regarding cost trends, rate adequacy and ultimate loss costs. ProAssurance considers the views of the actuaries as well as other factors, such as known, anticipated or estimated changes in frequency and severity of claims, loss retention levels and premium rates, in establishing the amount of its reserve for losses. The statutory filings of each insurance company with the insurance regulators must be accompanied by a consulting actuary's certification as to their respective reserves. ProAssurance partitions its reserve by accident year, which is the year in which the claim becomes its liability. As claims are incurred (reported) and claim payments are made, they are aggregated by accident year for analysis purposes. ProAssurance also partitions its reserve by reserve type: case reserves and IBNR reserves. Case reserves are established by the claims department based upon the particular circumstances of each reported claim and represent ProAssurance’s estimate of the future loss costs (often referred to as expected losses) that will be paid on reported claims. Case reserves are decremented as claim payments are made and are periodically adjusted upward or downward as estimates regarding the amount of future losses are revised; a reported loss for an individual claim equates to the case reserve at any point in time plus the claim payments that have been made to date. IBNR reserves represent an estimate, in the aggregate, of future development on losses that have been reported to ProAssurance plus an estimate of losses that have been incurred but not reported. Development of Prior Accident Years In addition to setting the initial reserve for the current accident year, each period ProAssurance reassesses the amount of reserve required for prior accident years. The foundation of ProAssurance’s reserve re-estimation process is an actuarial analysis that is performed by both the internal and consulting actuaries. This detailed analysis projects ultimate losses on a line of business, geographic, coverage layer and accident year basis. The procedure uses the most representative data for each partition, capturing its unique patterns of development and trends. In all, there are 219 different partitions of ProAssurance's business for purposes of this analysis. ProAssurance believes that the use of consulting actuaries provides an independent view of the loss data as well as a broader perspective on industry loss trends. Activity in the Reserve for losses and loss adjustment expenses is summarized as follows: (In thousands) Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Year Ended December 31, 2016 Balance, beginning of year $ 1,993,428 $ 2,005,326 $ 2,005,326 Less reinsurance recoverables on unpaid losses and loss adjustment expenses 273,475 249,350 249,350 Net balance, beginning of year 1,719,953 1,755,976 1,755,976 Net reserves acquired from acquisitions — — — Net losses: Current year 147,927 139,660 587,007 Favorable development of reserves established in prior years, net (28,776 ) (28,705 ) (143,778 ) Total 119,151 110,955 443,229 Paid related to: Current year (33,085 ) (26,411 ) (96,190 ) Prior years (80,709 ) (80,154 ) (383,062 ) Total paid (113,794 ) (106,565 ) (479,252 ) Net balance, end of period 1,725,310 1,760,367 1,719,953 Plus reinsurance recoverables on unpaid losses and loss adjustment expenses 271,679 245,403 273,475 Balance, end of period $ 1,996,989 $ 2,005,770 $ 1,993,428 The favorable loss development recognized in the three months ended March 31, 2017 primarily reflected a lower than anticipated claims severity trend (i.e., the average size of a claim) for accident years 2009 through 2014 . The favorable loss development recognized in the three months ended March 31, 2016 primarily reflected a lower than anticipated claims severity trend for accident years 2009 through 2013 . The favorable loss development recognized in the twelve months ended December 31, 2016 primarily reflected a lower than anticipated claims severity trend for accident years 2008 through 2014. For additional information regarding ProAssurance's reserve, see Note 1 of the Notes to Consolidated Financial Statements included in ProAssurance's December 31, 2016 Form 10-K.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies ProAssurance is involved in various legal actions related to insurance policies and claims handling including, but not limited to, claims asserted by policyholders. These types of legal actions arise in the Company's ordinary course of business and, in accordance with GAAP for insurance entities, are considered as a part of the Company's loss reserving process, which is described in detail under the heading "Losses and Loss Adjustment Expenses" in the Accounting Policies section in Note 1 of the Notes to Consolidated Financial Statements in ProAssurance's 2016 Form 10-K. ProAssurance has funding commitments primarily related to non-public investment entities totaling approximately $138.4 million , expected to be paid as follows: $55.3 million in 2017 , $52.8 million in 2018 and 2019 combined, $25.4 million in 2020 and 2021 combined and $4.9 million thereafter. Of these funding commitments, $1.4 million are related to qualified affordable housing project tax credit investments and are expected to be paid as follows: $0.3 million in 2017 , $0.3 million in 2018 and 2019 combined, $0.3 million in 2020 and 2021 combined and $0.5 million thereafter. As a member of Lloyd's we are required to provide capital to support Syndicate 1729 through 2022 of up to $200 million , referred to as FAL . At March 31, 2017 , ProAssurance is satisfying the FAL requirement with investment securities on deposit with Lloyd's with a carrying value of $97.7 million (see Note 3 of the Notes to Condensed Consolidated Financial Statements). ProAssurance has issued an unconditional revolving credit agreement to the Premium Trust Fund of Syndicate 1729 for the purpose of providing working capital. Permitted borrowings are £20.0 million under an amended Syndicate Credit Agreement executed in April 2016. Under the amended Syndicate Credit Agreement advances bear interest at 3.8% annually, and may be repaid at any time but are repayable upon demand after December 31, 2019 . As of March 31, 2017 , the unused commitment under the Syndicate Credit Agreement approximated £12.4 million (approximately $15.6 million as of March 31, 2017 ). In conjunction with a strategic business partnership ProAssurance entered into during the third quarter of 2016, ProAssurance issued a line of credit of up to $9.0 million for the purpose of funding the entity's operations. The line of credit is non-interest bearing and may be repaid at any time but is repayable upon demand on or before August 31, 2017 . As of March 31, 2017 , the unused commitment under the line of credit approximated $4.9 million .

Debt

Debt	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Long-term Debt	Debt ProAssurance’s outstanding debt consisted of the following: (In thousands) March 31, December 31, Senior notes due 2023, unsecured, interest at 5.3% annually $ 250,000 $ 250,000 Revolving Credit Agreement, outstanding borrowings are fully secured, see Note 3, and carried at a weighted average interest rate of 1.44% and 1.35%, respectively. Outstanding borrowings are not permitted to exceed $250 million aggregately; Revolving Credit Agreement expires in 2020. The interest rate on the borrowings is set at the time the respective borrowing is initiated or renewed. The current borrowings can be repaid or renewed in the second quarter 2017. If renewed, the interest rate will be reset. 200,000 200,000 Total principal 450,000 450,000 Less debt issuance costs 1,712 1,798 Debt less debt issuance costs $ 448,288 $ 448,202 Covenant Compliance There are no financial covenants associated with the Senior Notes due 2023. The Revolving Credit Agreement contains customary representations, covenants and events constituting default, and remedies for default. The Revolving Credit Agreement also defines financial covenants regarding permitted leverage ratios. ProAssurance is currently in compliance with all covenants of the Revolving Credit Agreement . Additional Information For additional information regarding ProAssurance's debt, see Note 10 of the Notes to Consolidated Financial Statements included in ProAssurance's December 31, 2016 Form 10-K.

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity At March 31, 2017 and December 31, 2016 , ProAssurance had 100 million shares of authorized common stock and 50 million shares of authorized preferred stock. The Board has the authority to determine provisions for the issuance of preferred shares, including the number of shares to be issued, the designations, powers, preferences and rights, and the qualifications, limitations or restrictions of such shares. To date, the Board has not approved the issuance of preferred stock. ProAssurance declared cash dividends of $0.31 per share during the first quarters of both 2017 and 2016 , totaling $16.5 million and $16.4 million , respectively. At March 31, 2017 , Board authorizations for the repurchase of common shares or the retirement of outstanding debt of $109.6 million remained available for use. ProAssurance did no t repurchase any common shares during the three months ended March 31, 2017 and repurchased approximately 27,700 shares at a cost of $1.3 million during the three months ended March 31, 2016 . Share-based compensation expense and related tax benefits were as follows: Three Months Ended March 31 (In thousands) 2017 2016 Share-based compensation expense $ 3,346 $ 2,715 Related tax benefits $ 1,171 $ 950 ProAssurance awarded approximately 84,600 restricted share units and 48,000 base performance share units to employees in February 2017 . The fair value of each unit awarded was estimated at $58.35 , equal to the market value of a ProAssurance common share on the date of grant less the estimated present value of dividends during the vesting period. All awards are charged to expense as an increase to equity over the service period (generally the vesting period) associated with the award. Restricted share units and performance share units vest in their entirety at the end of a three -year period following the grant date based on a continuous service requirement and, for performance share units, achievement of a performance objective. Partial vesting is permitted for retirees. A ProAssurance common share is issued for each unit once vesting requirements are met, except that units sufficient to satisfy required tax withholdings are paid in cash. The number of common shares issued for performance share units varies from 50% to 200% of base awards depending upon the degree to which stated performance objectives are achieved. ProAssurance issued approximately 29,300 and 99,500 common shares to employees in February 2017 related to restricted share units and performance share units, respectively, granted in 2014. Performance share units for the 2014 award were issued at levels ranging from 117% to 125% . ProAssurance issued approximately 9,000 common shares to employees in February 2017 as bonus compensation, as approved by the Compensation Committee of the Board. The shares issued were valued at fair value (the market price of a ProAssurance common share on the date of award). Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss) For the three months ended March 31, 2017 and 2016 , OCI was primarily comprised of unrealized gains and losses, including non-credit impairment losses, arising during the period related to available-for-sale securities, less reclassification adjustments, as shown in the table that follows, net of tax. For the three months ended March 31, 2016 , OCI included gains of $0.3 million related to changes from the reestimation of two defined benefit plans assumed in the Eastern acquisition, one of which was terminated late in 2016. The remaining plan is frozen as to the earnings of additional benefits, but the unrecognized plan benefit liability is reestimated annually. At March 31, 2017 and December 31, 2016 , AOCI was primarily comprised of unrealized gains and losses from available-for-sale securities, including non-credit impairments recognized in OCI of $0.5 million and $0.3 million , respectively, net of tax. During 2016 , as discussed above, one of the defined benefit plans assumed in the Eastern acquisition was terminated and the related unrecognized losses were reclassified from AOCI to earnings. At March 31, 2017 and December 31, 2016 , unrecognized changes in the remaining defined benefit plan liability were nominal in amount. All tax effects were computed using a 35% rate, with the exception of unrealized gains and losses on available-for-sale securities held at our U.K. and Cayman Island entities which were immaterial in amount. Amounts reclassified from AOCI to Net income and the amounts of deferred tax expense (benefit) included in OCI were as follows: Three Months Ended March 31 (In thousands) 2017 2016 Reclassifications from AOCI to Net income: Realized investment gains (losses) $ 1,616 $ (5,241 ) Non-credit impairment losses reclassified to earnings, due to sale of securities or reclassification as a credit loss — (2,758 ) Total amounts reclassified, before tax effect 1,616 (7,999 ) Tax effect (at 35%) (566 ) 2,800 Net reclassification adjustments $ 1,050 $ (5,199 ) Deferred tax expense (benefit) included in OCI $ 1,481 $ 12,260

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2017
Variable Interest Entities [Abstract]
Variable Interest Entities	Variable Interest Entities ProAssurance holds passive interests in a number of entities that are considered to be VIE s under GAAP guidance. ProAssurance's VIE interests principally consist of interests in LP s/ LLC s formed for the purpose of achieving diversified equity and debt returns. ProAssurance's VIE interests carried as a part of Other investments totaled $26.9 million at both March 31, 2017 and December 31, 2016 . ProAssurance's VIE interests carried as a part of Investment in unconsolidated subsidiaries totaled $270.7 million at March 31, 2017 and $282.3 million at December 31, 2016 . ProAssurance does not have power over the activities that most significantly impact the economic performance of these VIE s and thus is not the primary beneficiary. Therefore, ProAssurance has not consolidated these VIE s. ProAssurance’s involvement with each entity is limited to its direct ownership interest in the entity. Except as disclosed in Note 7 of the Notes to Condensed Consolidated Financial Statements, ProAssurance has no arrangements with any of the entities to provide other financial support to or on behalf of the entity. At March 31, 2017 , ProAssurance’s maximum loss exposure relative to these investments was limited to the carrying value of ProAssurance’s investment in the VIE .

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Diluted weighted average shares is calculated as basic weighted average shares plus the effect, calculated using the treasury stock method, of assuming that performance and restricted share units and purchase match units have vested. All outstanding performance and restricted share units and purchase match units had a dilutive effect for the three months ended March 31, 2017 and 2016 .

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information ProAssurance operates in four segments that are organized around the nature of the products and services provided: Specialty P&C , Workers' Compensation, Lloyd's Syndicate, and Corporate. A description of each segment follows. Specialty P&C is primarily focused on professional liability insurance and medical technology liability insurance. Professional liability insurance is primarily offered to healthcare providers and institutions and to attorneys and their firms. Medical technology liability insurance is offered to medical technology and life sciences companies that manufacture or distribute products including entities conducting human clinical trials. The Specialty P&C segment cedes certain premium to the Lloyd's Syndicate segment under a quota share agreement with Syndicate 1729 . As discussed below, Syndicate 1729 operating results are reported on a quarter delay. For consistency purposes, results from this ceding arrangement, other than cash receipts or disbursements, have been reported within the Specialty P&C segment on the same one quarter delay. Workers' Compensation provides workers' compensation products primarily to employers with 1,000 or fewer employees. The segment also offers alternative market solutions whereby policies written are 100% ceded either to captive insurers unaffiliated with ProAssurance or to SPC s operated by a wholly owned subsidiary of ProAssurance. Each SPC is owned, fully or in part, by an agency, group or association. Operating results (underwriting profit or loss, plus investment results reported in the Corporate segment) of the SPC s are due to the owners of that cell. Lloyd's Syndicate includes operating results from ProAssurance's 58% participation in Lloyd's of London Syndicate 1729 . Syndicate 1729 underwrites risks over a wide range of property and casualty insurance and reinsurance lines in both the U.S. and international markets. The results of this segment are reported on a quarter delay, except that investment results associated with investment assets solely allocated to Syndicate 1729 operations and certain U.S. paid administrative expenses are reported concurrently as that information is available on an earlier time frame. Corporate includes ProAssurance's investment operations, interest expense and U.S. income taxes, all of which are managed at the corporate level with the exception of investment assets solely allocated to Syndicate 1729 as discussed above. The segment also includes non-premium revenues generated outside of our insurance entities and corporate expenses. The accounting policies of the segments are the same as those described in Note 1 of the Notes to Consolidated Financial Statements in ProAssurance’s December 31, 2016 report on Form 10-K and Note 1 of the Notes to Condensed Consolidated Financial Statements. ProAssurance evaluates performance of its Specialty P&C and Workers' Compensation segments based on before tax underwriting profit or loss, which excludes investment performance. Performance of the Lloyd's Syndicate segment is evaluated based on underwriting profit or loss, plus investment results of investment assets solely allocated to Syndicate 1729 operations, net of U.K. income tax expense. Performance of the Corporate segment is evaluated based on the contribution made to consolidated after tax results. ProAssurance accounts for inter-segment transactions as if the transactions were to third parties at current market prices. Assets are not allocated to segments because investments and other assets are not managed at the segment level. Financial results by segment were as follows: Three Months Ended March 31, 2017 (In thousands) Specialty P&C Workers' Compensation Lloyd's Syndicate Corporate Inter-segment Eliminations Consolidated Net premiums earned $ 113,058 $ 55,283 $ 14,562 $ — $ — $ 182,903 Net investment income — — 372 22,814 — 23,186 Equity in earnings (loss) of unconsolidated subsidiaries — — — 1,808 — 1,808 Net realized gains (losses) — — 27 13,253 — 13,280 Other income 1,198 145 391 173 (86 ) 1,821 Net losses and loss adjustment expenses (74,994 ) (34,650 ) (9,507 ) — — (119,151 ) Underwriting, policy acquisition and operating expenses (25,977 ) (16,691 ) (6,211 ) (8,315 ) 86 (57,108 ) Segregated portfolio cells dividend (expense) income (1) 28 (1,174 ) — (1,229 ) — (2,375 ) Interest expense — — — (4,133 ) — (4,133 ) Income tax benefit (expense) — — 7 1,217 — 1,224 Segment operating results $ 13,313 $ 2,913 $ (359 ) $ 25,588 $ — $ 41,455 Significant non-cash items: Depreciation and amortization, net of accretion $ 1,911 $ 837 $ (3 ) $ 5,058 $ — $ 7,803 Three Months Ended March 31, 2016 (In thousands) Specialty P&C Workers' Compensation Lloyd's Syndicate Corporate Inter-segment Eliminations Consolidated Net premiums earned $ 110,755 $ 54,383 $ 12,441 $ — $ — $ 177,579 Net investment income — — 315 25,125 — 25,440 Equity in earnings (loss) of unconsolidated subsidiaries — — — (3,634 ) — (3,634 ) Net realized gains (losses) — — (5 ) (8,347 ) — (8,352 ) Other income 1,276 471 252 458 (103 ) 2,354 Net losses and loss adjustment expenses (2) (71,174 ) (35,027 ) (6,189 ) — 1,435 (110,955 ) Underwriting, policy acquisition and operating expenses (2) (25,054 ) (17,829 ) (5,167 ) (7,507 ) (1,332 ) (56,889 ) Segregated portfolio cells dividend (expense) income (1) — (713 ) — (463 ) — (1,176 ) Interest expense — — — (3,686 ) — (3,686 ) Income tax benefit (expense) — — (84 ) (1,280 ) — (1,364 ) Segment operating results $ 15,803 $ 1,285 $ 1,563 $ 666 $ — $ 19,317 Significant non-cash items: Depreciation and amortization, net of accretion $ 2,011 $ 1,404 $ 66 $ 5,149 $ — $ 8,630 (1) During the first quarter of 2017, ProAssurance began reporting in the Corporate segment the portion of the SPC dividend (expense) income that is attributable to the investment results of the SPCs, all of which are reported in the Corporate segment, to better align the expense with the related investment results of the SPCs. For comparative purposes, ProAssurance has reflected the SPC dividend expense for 2016 in the same manner. (2) In the first quarter of 2016, the portion of the management fee that was allocated to ULAE was eliminated in consolidation. During the second quarter of 2016, ProAssurance discontinued the practice of eliminating in consolidation the portion of the management fee that was allocated to ULAE, thus there was no similar elimination in the first quarter of 2017. The following table provides detailed information regarding ProAssurance's gross premiums earned by product as well as a reconciliation to net premiums earned. All gross premiums earned are from external customers except as noted. ProAssurance's insured risks are primarily within the U.S. Three Months Ended March 31 (In thousands) 2017 2016 Specialty P&C Segment Gross premiums earned: Healthcare professional liability $ 117,051 $ 113,749 Legal professional liability 6,317 6,614 Medical technology liability 8,312 8,550 Other 102 268 Ceded premiums earned (18,724 ) (18,426 ) Segment net premiums earned 113,058 110,755 Workers' Compensation Segment Gross premiums earned: Traditional business 41,768 42,650 Alternative market business 19,446 18,294 Ceded premiums earned (5,931 ) (6,561 ) Segment net premiums earned 55,283 54,383 Lloyd's Syndicate Segment Gross premiums earned: Property and casualty* 17,185 13,373 Ceded premiums earned (2,623 ) (932 ) Segment net premiums earned 14,562 12,441 Consolidated Net premiums earned $ 182,903 $ 177,579 *Includes premium assumed from the Specialty P&C segment of $3.5 million for the three months ended March 31, 2017 and $3.6 million for the three months ended March 31, 2016 .

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events In April 2017, ProAssurance repaid $10 million of the balance outstanding on the Revolving Credit Agreement (see Note 8 of the Notes to Condensed Consolidated Financial Statements for further discussion of the terms of the Revolving Credit Agreement ).

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounting Changes Adopted and Not Yet Adopted	Accounting Changes Adopted Improvements to Employee Share-Based Payment Accounting Effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years, the FASB issued guidance that simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of cash flows, and the classification of awards as either equity or liabilities. Under the new guidance, the difference between the deduction for tax purposes and the compensation cost recognized for financial reporting purposes is to be recognized as income tax expense in the current period and included with other income tax cash flows as an operating activity. The threshold for equity classification has also been revised to permit withholdings up to the maximum statutory tax rates in the applicable jurisdictions. The update also provides an accounting policy election to account for forfeitures as they occur. ProAssurance adopted the guidance as of January 1, 2017. The primary effects of the adoption on the current period are the following: (1) using a prospective application, ProAssurance recorded unrecognized excess tax benefits of $2.3 million as a current tax expense, (2) using a modified retrospective application, ProAssurance elected to recognize forfeitures as they occur and recorded a $0.4 million increase to Additional paid-in capital and a respective $0.3 million reduction to Retained earnings and a $0.1 million increase to deferred taxes to reflect the incremental share-based compensation expense, net of related tax impacts, that would have been recognized in prior years under the modified guidance and (3) excess tax benefits from share-based compensation of $2.3 million was reclassified from financing activities to operating activities in the Condensed Consolidated Statements of Cash Flows. Interests Held Through Related Parties that are Under Common Control Effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years, the FASB issued additional guidance regarding consolidation of legal entities such as limited partnerships, limited liability corporations, and securitization structures (collateralized debt obligations, collateralized loan obligations, and mortgage-backed security transactions). The new guidance modifies the criteria used by a reporting entity when determining if it is a primary beneficiary of a VIE when there are entities under common control and the reporting entity has indirect interests in the VIE through related party relationships. ProAssurance adopted the guidance as of January 1, 2017. Adoption of the guidance had no material effect on ProAssurance’s results of operations or financial position. Simplifying the Transition to the Equity Method of Accounting Effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years, the FASB issued guidance that eliminates the requirement for retroactive restatement when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence. The new guidance provides that the cost of acquiring an additional interest in an investee is to be added to the current basis of an investor’s previously held interest and the equity method of accounting adopted as of the date the investment becomes qualified for equity method accounting with no retroactive adjustment of the investment. If an available-for-sale equity security qualifies for the equity method of accounting the unrealized holding gain or loss in accumulated other comprehensive income is to be recognized through earnings at the date the investment becomes qualified for use of the equity method. ProAssurance adopted the guidance as of January 1, 2017. Adoption of the guidance had no material effect on ProAssurance’s results of operations or financial position. Accounting Changes Not Yet Adopted Clarifying the Definition of a Business Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance which provides clarification of the definition of a business, affecting areas such as acquisitions, disposals, goodwill and consolidation. The new guidance intends to assist entities with determining whether a transaction should be accounted for as an acquisition or disposal of assets or a business. ProAssurance plans to adopt the guidance beginning January 1, 2018. Adoption is not expected to have a material effect on ProAssurance’s results of operations or financial position. Restricted Cash Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance related to the classification of restricted cash presented in the statement of cash flows with the objective of reducing diversity in practice. Under the new guidance, entities are required to include restricted cash and restricted cash equivalents with cash and cash equivalents when reconciling beginning-of-period and end-of-period total amounts as presented on the statement of cash flows. ProAssurance plans to adopt the guidance beginning January 1, 2018. Adoption is not expected to have a material effect on ProAssurance’s results of operations or financial position as it affects disclosure only. Intra-Entity Transfers of Assets Other than Inventory Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance which reduces the complexity in accounting standards related to the income tax consequences of intra-entity transfers of assets other than inventory. Under the new guidance, entities are required to recognize income tax consequences of an intra-entity transfer of assets other than inventory when the transfer occurs instead of delaying recognition until the asset has been sold to an outside party. ProAssurance is in the process of evaluating the effect the new guidance would have on its results of operations and financial position and plans to adopt the guidance beginning January 1, 2018. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position. Classification of Certain Cash Receipts and Cash Payments Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance related to the classification of certain cash receipts and cash payments presented in the statement of cash flows with the objective of reducing diversity in practice. ProAssurance plans to adopt the guidance beginning January 1, 2018. Adoption is not expected to have a material effect on ProAssurance’s results of operations or financial position as it affects disclosure only. Revenue from Contracts with Customers Effective for fiscal years beginning after December 15, 2017 the FASB issued guidance related to revenue from contracts with customers. The core principle of the new guidance is that revenue is recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ProAssurance plans to adopt the guidance beginning January 1, 2018. As the majority of ProAssurance's revenues come from insurance contracts which fall under the scope of other FASB standards, adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position. Recognition and Measurement of Financial Assets and Financial Liabilities Effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, the FASB issued guidance that requires equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. The new guidance also specifies that an entity use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and present financial assets and liabilities by measurement category and form of financial asset. Other provisions of the new guidance include: revised disclosure requirements related to the presentation in comprehensive income of changes in the fair value of liabilities; elimination, for public companies, of disclosure requirements relative to the method(s) and significant assumptions underlying fair values disclosed for financial instruments measured at amortized cost; and simplified impairment assessments for equity investments without readily determinable fair values. ProAssurance plans to adopt the guidance beginning January 1, 2018. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position. Premium Amortization on Purchased Callable Debt Securities Effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, the FASB issued guidance that will require the premium for certain callable debt securities to be amortized over a shorter period than is currently required. Currently amortization is permitted over the contractual life of the instrument and the guidance shortens the amortization to the earliest call date. The purpose of the guidance is to more closely align the amortization period of premiums to expectations incorporated in market pricing on the underlying securities. ProAssurance plans to adopt the guidance beginning January 1, 2019. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position. Leases Effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, the FASB issued guidance that requires a lessee to recognize for all leases (with the exception of short-term leases) a lease liability, which is a lessee's obligation to make lease payments arising from a lease, measured on a discounted basis, and a right-of-use asset, which is an asset that represents the lessee's right to use, or control the use of, a specified asset for the lease term. ProAssurance plans to adopt the guidance beginning January 1, 2019. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position as ProAssurance does not have any leases it believes to be material. Simplifying the Test for Goodwill Impairment Effective for the fiscal years beginning after December 15, 2019 and interim periods within those fiscal years, the FASB issued guidance that simplifies the requirements to test goodwill for impairment for business entities that have goodwill reported in their financial statements. The guidance eliminates the second step of the impairment test which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount. In addition, the guidance also eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment. ProAssurance plans to adopt the guidance beginning January 1, 2020. Adoption is not expected to have a material effect on ProAssurance’s results of operations or financial position. Improvements to Financial Instruments - Credit Losses Effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years, the FASB issued guidance that replaces the incurred loss impairment methodology, which delays recognition of credit losses until a probable loss has been incurred, with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Under the new guidance, credit losses are required to be recorded through an allowance for credit losses account and the income statement reflects the measurement for newly recognized financial assets, as well as increases or decreases of expected credit losses that have taken place during the period. ProAssurance is in the process of evaluating the effect the new guidance would have on its results of operations and financial position and plans to adopt the guidance beginning January 1, 2020. Adoption of the guidance is not expected to have a material effect on ProAssurance’s results of operations or financial position.

Basis of Presentation (Tables)

Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other Liabilities	Other liabilities consisted of the following: (In millions) March 31, 2017 December 31, 2016 SPC dividends payable $ 37.0 $ 34.3 Unpaid dividends 16.5 265.7 All other 116.8 122.3 Total other liabilities $ 170.3 $ 422.3

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value	Fair values of assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 are shown in the following tables. Where applicable, the tables also indicate the fair value hierarchy of the valuation techniques utilized to determine those fair values. For some assets, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. When this is the case, the asset is categorized based on the level of the most significant input to the fair value measurement. Assessments of the significance of a particular input to the fair value measurement require judgment and consideration of factors specific to the assets being valued. March 31, 2017 Fair Value Measurements Using Total (In thousands) Level 1 Level 2 Level 3 Fair Value Assets: Fixed maturities, available for sale U.S. Treasury obligations $ — $ 148,211 $ — $ 148,211 U.S. Government-sponsored enterprise obligations — 28,701 — 28,701 State and municipal bonds — 770,061 — 770,061 Corporate debt, multiple observable inputs 2,395 1,284,664 — 1,287,059 Corporate debt, limited observable inputs — — 18,914 18,914 Residential mortgage-backed securities — 207,906 — 207,906 Agency commercial mortgage-backed securities — 12,688 — 12,688 Other commercial mortgage-backed securities — 19,697 — 19,697 Other asset-backed securities — 108,190 3,002 111,192 Equity securities Financial 84,052 — — 84,052 Utilities/Energy 51,304 — — 51,304 Consumer oriented 60,686 — — 60,686 Industrial 52,497 — — 52,497 Bond funds 92,753 — — 92,753 All other 49,914 — — 49,914 Short-term investments 277,494 2,847 — 280,341 Other investments 1,270 27,805 903 29,978 Total assets categorized within the fair value hierarchy $ 672,365 $ 2,610,770 $ 22,819 3,305,954 LP/LLC interests carried at NAV which approximates fair value. These interests, reported as a part of Investment in unconsolidated subsidiaries, are not categorized within the fair value hierarchy. 199,696 Total assets at fair value $ 3,505,650 December 31, 2016 Fair Value Measurements Using Total (In thousands) Level 1 Level 2 Level 3 Fair Value Assets: Fixed maturities, available for sale U.S. Treasury obligations $ — $ 146,539 $ — $ 146,539 U.S. Government-sponsored enterprise obligations — 30,235 — 30,235 State and municipal bonds — 800,463 — 800,463 Corporate debt, multiple observable inputs 2,339 1,261,842 — 1,264,181 Corporate debt, limited observable inputs — — 14,810 14,810 Residential mortgage-backed securities — 217,906 — 217,906 Agency commercial mortgage-backed securities — 12,783 — 12,783 Other commercial mortgage-backed securities — 19,611 — 19,611 Other asset-backed securities — 103,871 3,007 106,878 Equity securities Financial 81,749 — — 81,749 Utilities/Energy 52,869 — — 52,869 Consumer oriented 61,284 — — 61,284 Industrial 54,265 — — 54,265 Bond funds 79,843 10,159 — 90,002 All other 27,181 19,924 — 47,105 Short-term investments 437,580 4,504 — 442,084 Other investments 1,956 29,542 3 31,501 Total assets categorized within the fair value hierarchy $ 799,066 $ 2,657,379 $ 17,820 3,474,265 LP/LLC interests carried at NAV which approximates fair value. These interests, reported as a part of Investment in unconsolidated subsidiaries, are not categorized within the fair value hierarchy. 204,719 Total assets at fair value $ 3,678,984
Summary of quantitative information about Level 3 fair value measurements	Quantitative Information Regarding Level 3 Valuations Fair Value at (In thousands) March 31, 2017 December 31, 2016 Valuation Technique Unobservable Input Range Assets: Corporate debt, limited observable inputs $18,914 $14,810 Market Comparable Comparability Adjustment 0% - 5% (2.5%) Discounted Cash Flows Comparability Adjustment 0% - 5% (2.5%) Other asset-backed securities $3,002 $3,007 Market Comparable Comparability Adjustment 0% - 5% (2.5%) Discounted Cash Flows Comparability Adjustment 0% - 5% (2.5%) Other investments $903 $3 Discounted Cash Flows Comparability Adjustment 0% - 10% (5%)
Summary of changes in the fair value of assets measured at fair value	The following tables (the Level 3 Tables) present summary information regarding changes in the fair value of assets measured at fair value using Level 3 inputs. March 31, 2017 Level 3 Fair Value Measurements – Assets (In thousands) Corporate Debt Asset-backed Securities All other investments Total Balance December 31, 2016 $ 14,810 $ 3,007 $ 3 $ 17,820 Total gains (losses) realized and unrealized: Included in earnings, as a part of: Net investment income (39 ) — — (39 ) Net realized investment gains (losses) 13 — — 13 Included in other comprehensive income (208 ) (5 ) 2 (211 ) Purchases 7,048 — — 7,048 Sales (1,712 ) — — (1,712 ) Transfers in — — 898 898 Transfers out (998 ) — — (998 ) Balance March 31, 2017 $ 18,914 $ 3,002 $ 903 $ 22,819 Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end $ — $ — $ — $ — March 31, 2016 Level 3 Fair Value Measurements – Assets (In thousands) Corporate Debt Asset-backed Securities All other investments Total Balance December 31, 2015 $ 14,500 $ 757 $ — $ 15,257 Total gains (losses) realized and unrealized: Included in earnings, as a part of: Net investment income (14 ) — (1 ) (15 ) Net realized investment gains (losses) (75 ) — — (75 ) Included in other comprehensive income (75 ) (2 ) (1 ) (78 ) Purchases — 3,500 1,560 5,060 Sales (681 ) (167 ) — (848 ) Transfers in — — — — Transfers out (6 ) — — (6 ) Balance March 31, 2016 $ 13,649 $ 4,088 $ 1,558 $ 19,295 Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end $ — $ — $ — $ —
Investments in Limited liability companies and limited partnerships	Investments in unconsolidated subsidiaries at both March 31, 2017 and December 31, 2016 included interests in investment fund LP s/ LLC s that measure fund assets at fair value on a recurring basis and that provide a NAV for the interest. The carrying value of these interests is based on the NAV provided and was considered to approximate the fair value of the interests. In accordance with GAAP , the fair value of these investments was not classified within the fair value hierarchy. Additional information regarding these investments is as follows: Unfunded Fair Value (In thousands) March 31, March 31, December 31, Investments in LPs/LLCs: Private debt funds (1) $11,972 $ 51,307 $ 55,637 Long equity fund (2) None 6,770 6,268 Long/short equity funds (3) None 29,944 28,926 Non-public equity funds (4) $55,334 86,506 89,691 Multi-strategy fund of funds (5) None 8,668 8,448 Structured credit fund (6) None 4,466 4,273 Long/short commodities fund (7) None 12,035 11,476 $ 199,696 $ 204,719 (1) The investment is comprised of interests in two unrelated LP funds that are structured to provide interest distributions primarily through diversified portfolios of private debt instruments. One LP allows redemption by special consent; the other does not permit redemption. Income and capital are to be periodically distributed at the discretion of the LP s over an anticipated time frame that spans from three to eight years. (2) The fund is a LP that holds long equities of public international companies. Redemptions are allowed at the end of any calendar month with a prior notice requirement of 15 days and are paid within 10 days of the end of the calendar month of the redemption request. (3) The investment is comprised of interests in multiple unrelated LP funds. The funds hold primarily long and short North American equities and target absolute returns using strategies designed to take advantage of market opportunities. The funds generally permit quarterly or semi-annual capital redemptions subject to notice requirements of 30 to 90 days. For some funds, redemptions above specified thresholds (lowest threshold is 90% ) may be only partially payable until after a fund audit is completed and are then payable within 30 days. (4) The investment is comprised of interests in multiple unrelated LP funds, each structured to provide capital appreciation through diversified investments in private equity, which can include investments in buyout, venture capital, mezzanine debt, distressed debt, and other private equity-oriented LP s. Two of the LP s allow redemption by terms set forth in the LP agreements; the others do not permit redemption. Income and capital are to be periodically distributed at the discretion of the LP over time frames that are anticipated to span up to nine years. (5) This fund is a LLC structured to build and manage low volatility, multi-manager portfolios that have little or no correlation to the broader fixed income and equity security markets. Redemptions are not permitted but offers to repurchase units of the LLC may be extended periodically. (6) This fund is a LP seeking to obtain superior risk-adjusted absolute returns by acquiring and actively managing a diversified portfolio of debt securities, including bonds, loans and other asset-backed instruments. Redemptions are allowed at any quarter-end with a prior notice requirement of 90 days . (7) This fund is a LLC invested across a broad range of commodities and focuses primarily on market neutral, relative value strategies, seeking to generate absolute returns with low correlation to broad commodity, equity and fixed income markets. Following an initial one year lock-up period, redemptions are allowed with a prior notice requirement of 30 days and are payable within 30 days.
Financial instruments not measured at fair value	The following table provides the estimated fair value of our financial instruments that, in accordance with GAAP for the type of investment, are measured using a methodology other than fair value. All fair values provided fall within the Level 3 fair value category. March 31, 2017 December 31, 2016 (In thousands) Carrying Fair Carrying Fair Financial assets: BOLI $ 60,589 $ 60,589 $ 60,134 $ 60,134 Other investments $ 50,598 $ 62,061 $ 50,391 $ 58,757 Other assets $ 29,196 $ 29,072 $ 29,111 $ 28,960 Financial liabilities: Senior notes due 2023 $ 250,000 $ 274,315 $ 250,000 $ 270,898 Revolving Credit Agreement $ 200,000 $ 200,000 $ 200,000 $ 200,000 Other liabilities $ 17,855 $ 17,855 $ 17,033 $ 17,011

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Amortized cost and estimated fair value of available-for-sale fixed maturities and equity securities	Available-for-sale securities at March 31, 2017 and December 31, 2016 included the following: March 31, 2017 (In thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Fixed maturities U.S. Treasury obligations $ 147,826 $ 1,203 $ 818 $ 148,211 U.S. Government-sponsored enterprise obligations 28,621 241 161 28,701 State and municipal bonds 755,639 19,139 4,717 770,061 Corporate debt 1,291,140 21,812 6,979 1,305,973 Residential mortgage-backed securities 206,455 3,407 1,956 207,906 Agency commercial mortgage-backed securities 12,727 63 102 12,688 Other commercial mortgage-backed securities 19,650 153 106 19,697 Other asset-backed securities 111,214 191 213 111,192 $ 2,573,272 $ 46,209 $ 15,052 $ 2,604,429 December 31, 2016 (In thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Fixed maturities U.S. Treasury obligations $ 146,186 $ 1,264 $ 911 $ 146,539 U.S. Government-sponsored enterprise obligations 30,038 388 191 30,235 State and municipal bonds 790,154 17,261 6,952 800,463 Corporate debt 1,264,812 22,659 8,480 1,278,991 Residential mortgage-backed securities 216,285 3,667 2,046 217,906 Agency commercial mortgage-backed securities 12,837 89 143 12,783 Other commercial mortgage-backed securities 19,571 177 137 19,611 Other asset-backed securities 106,938 207 267 106,878 $ 2,586,821 $ 45,712 $ 19,127 $ 2,613,406
Schedule of available for sale securities by contractual maturity	The recorded cost basis and estimated fair value of available-for-sale fixed maturities at March 31, 2017 , by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (In thousands) Amortized Due in one Due after Due after Due after Total Fair Fixed maturities, available for sale U.S. Treasury obligations $ 147,826 $ 28,876 $ 98,304 $ 18,042 $ 2,989 $ 148,211 U.S. Government-sponsored enterprise obligations 28,621 12,863 7,781 7,918 139 28,701 State and municipal bonds 755,639 66,017 264,597 348,641 90,806 770,061 Corporate debt 1,291,140 122,549 764,626 388,119 30,679 1,305,973 Residential mortgage-backed securities 206,455 207,906 Agency commercial mortgage-backed securities 12,727 12,688 Other commercial mortgage-backed securities 19,650 19,697 Other asset-backed securities 111,214 111,192 $ 2,573,272 $ 2,604,429
Unconsolidated subsidiaries	ProAssurance holds investments in unconsolidated subsidiaries, accounted for under the equity method. The investments include the following: Carrying Value (In thousands) March 31, December 31, Investment in LPs/LLCs: Qualified affordable housing tax credit partnerships $ 99,005 $ 102,313 Other tax credit partnerships 11,041 11,459 All other LPs/LLCs 220,433 227,134 $ 330,479 $ 340,906
Other investments	Other investments at March 31, 2017 and December 31, 2016 were comprised as follows: (In thousands) March 31, December 31, Investments in LPs/LLCs, at cost $ 47,164 $ 46,852 Convertible securities, at fair value 29,978 31,501 Other, principally FHLB capital stock, at cost 3,434 3,539 $ 80,576 $ 81,892
Investments held in an unrealized loss position	The following tables provide summarized information with respect to investments held in an unrealized loss position at March 31, 2017 and December 31, 2016 , including the length of time the investment had been held in a continuous unrealized loss position. March 31, 2017 Total Less than 12 months 12 months or longer Fair Unrealized Fair Unrealized Fair Unrealized (In thousands) Value Loss Value Loss Value Loss Fixed maturities, available for sale U.S. Treasury obligations $ 82,630 $ 818 $ 82,630 $ 818 $ — $ — U.S. Government-sponsored enterprise obligations 10,507 161 10,507 161 — — State and municipal bonds 167,434 4,717 160,343 4,132 7,091 585 Corporate debt 416,640 6,979 382,246 4,361 34,394 2,618 Residential mortgage-backed securities 97,495 1,956 95,381 1,922 2,114 34 Agency commercial mortgage-backed securities 4,571 102 4,191 72 380 30 Other commercial mortgage-backed securities 10,890 106 9,075 85 1,815 21 Other asset-backed securities 46,008 213 42,018 207 3,990 6 $ 836,175 $ 15,052 $ 786,391 $ 11,758 $ 49,784 $ 3,294 December 31, 2016 Total Less than 12 months 12 months or longer Fair Unrealized Fair Unrealized Fair Unrealized (In thousands) Value Loss Value Loss Value Loss Fixed maturities, available for sale U.S. Treasury obligations $ 79,833 $ 911 $ 79,833 $ 911 $ — $ — U.S. Government-sponsored enterprise obligations 11,746 191 11,746 191 — — State and municipal bonds 224,884 6,952 219,276 6,444 5,608 508 Corporate debt 469,632 8,480 424,721 5,662 44,911 2,818 Residential mortgage-backed securities 103,680 2,046 100,542 1,982 3,138 64 Agency commercial mortgage-backed securities 4,579 143 4,192 114 387 29 Other commercial mortgage-backed securities 9,822 137 9,179 134 643 3 Other asset-backed securities 44,343 267 39,079 256 5,264 11 $ 948,519 $ 19,127 $ 888,568 $ 15,694 $ 59,951 $ 3,433
Net Investment Income	Net investment income by investment category was as follows: Three Months Ended (In thousands) 2017 2016 Fixed maturities $ 20,121 $ 22,575 Equities 3,644 3,643 Short-term and Other investments 801 405 BOLI 455 460 Investment fees and expenses (1,835 ) (1,643 ) Net investment income $ 23,186 $ 25,440
Net realized investment gains (losses)	The following table provides detailed information regarding Net realized investment gains (losses): Three Months Ended March 31 (In thousands) 2017 2016 Total OTTI losses: Corporate debt $ (419 ) $ (7,604 ) Other investments — (3,130 ) Portion of OTTI losses recognized in other comprehensive income before taxes: Corporate debt 248 1,068 Net impairment losses recognized in earnings (171 ) (9,666 ) Gross realized gains, available-for-sale securities 1,853 3,185 Gross realized (losses), available-for-sale securities (67 ) (4,647 ) Net realized gains (losses), trading securities 6,562 2,055 Net realized gains (losses), Other investments 1,172 52 Change in unrealized holding gains (losses), trading securities 3,616 733 Change in unrealized holding gains (losses), convertible securities, carried at fair value 313 (66 ) Other 2 2 Net realized investment gains (losses) $ 13,280 $ (8,352 )
Other than temporary impairment, credit losses recognized in earnings	The following table presents a roll forward of cumulative credit losses recorded in earnings related to impaired debt securities for which a portion of the OTTI was recorded in OCI . Three Months Ended March 31 (In thousands) 2017 2016 Balance beginning of period $ 1,158 $ 5,751 Additional credit losses recognized during the period, related to securities for which: No OTTI has been previously recognized 171 2,398 OTTI has been previously recognized — 2,154 Reductions due to: Securities sold during the period (realized) — (3,744 ) Balance March 31 $ 1,329 $ 6,559
Information regarding sales and purchases of available-for-sale securities	Other information regarding sales and purchases of available-for-sale securities is as follows: Three Months Ended March 31 (In millions) 2017 2016 Proceeds from sales (exclusive of maturities and paydowns) $ 79.2 $ 109.9 Purchases $ 160.4 $ 199.6

Reserve for Losses and Loss A24

Reserve for Losses and Loss Adjustment Expenses (Tables)	3 Months Ended
	Mar. 31, 2017
Insurance [Abstract]
Summary of reserve for losses and loss adjustment expenses	Activity in the Reserve for losses and loss adjustment expenses is summarized as follows: (In thousands) Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Year Ended December 31, 2016 Balance, beginning of year $ 1,993,428 $ 2,005,326 $ 2,005,326 Less reinsurance recoverables on unpaid losses and loss adjustment expenses 273,475 249,350 249,350 Net balance, beginning of year 1,719,953 1,755,976 1,755,976 Net reserves acquired from acquisitions — — — Net losses: Current year 147,927 139,660 587,007 Favorable development of reserves established in prior years, net (28,776 ) (28,705 ) (143,778 ) Total 119,151 110,955 443,229 Paid related to: Current year (33,085 ) (26,411 ) (96,190 ) Prior years (80,709 ) (80,154 ) (383,062 ) Total paid (113,794 ) (106,565 ) (479,252 ) Net balance, end of period 1,725,310 1,760,367 1,719,953 Plus reinsurance recoverables on unpaid losses and loss adjustment expenses 271,679 245,403 273,475 Balance, end of period $ 1,996,989 $ 2,005,770 $ 1,993,428

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	ProAssurance’s outstanding debt consisted of the following: (In thousands) March 31, December 31, Senior notes due 2023, unsecured, interest at 5.3% annually $ 250,000 $ 250,000 Revolving Credit Agreement, outstanding borrowings are fully secured, see Note 3, and carried at a weighted average interest rate of 1.44% and 1.35%, respectively. Outstanding borrowings are not permitted to exceed $250 million aggregately; Revolving Credit Agreement expires in 2020. The interest rate on the borrowings is set at the time the respective borrowing is initiated or renewed. The current borrowings can be repaid or renewed in the second quarter 2017. If renewed, the interest rate will be reset. 200,000 200,000 Total principal 450,000 450,000 Less debt issuance costs 1,712 1,798 Debt less debt issuance costs $ 448,288 $ 448,202

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Schedule of Share-based compensation expense and related tax benefits	Share-based compensation expense and related tax benefits were as follows: Three Months Ended March 31 (In thousands) 2017 2016 Share-based compensation expense $ 3,346 $ 2,715 Related tax benefits $ 1,171 $ 950
Reclassification adjustments related to available-for-sale securities	Amounts reclassified from AOCI to Net income and the amounts of deferred tax expense (benefit) included in OCI were as follows: Three Months Ended March 31 (In thousands) 2017 2016 Reclassifications from AOCI to Net income: Realized investment gains (losses) $ 1,616 $ (5,241 ) Non-credit impairment losses reclassified to earnings, due to sale of securities or reclassification as a credit loss — (2,758 ) Total amounts reclassified, before tax effect 1,616 (7,999 ) Tax effect (at 35%) (566 ) 2,800 Net reclassification adjustments $ 1,050 $ (5,199 ) Deferred tax expense (benefit) included in OCI $ 1,481 $ 12,260

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Financial results by segment were as follows: Three Months Ended March 31, 2017 (In thousands) Specialty P&C Workers' Compensation Lloyd's Syndicate Corporate Inter-segment Eliminations Consolidated Net premiums earned $ 113,058 $ 55,283 $ 14,562 $ — $ — $ 182,903 Net investment income — — 372 22,814 — 23,186 Equity in earnings (loss) of unconsolidated subsidiaries — — — 1,808 — 1,808 Net realized gains (losses) — — 27 13,253 — 13,280 Other income 1,198 145 391 173 (86 ) 1,821 Net losses and loss adjustment expenses (74,994 ) (34,650 ) (9,507 ) — — (119,151 ) Underwriting, policy acquisition and operating expenses (25,977 ) (16,691 ) (6,211 ) (8,315 ) 86 (57,108 ) Segregated portfolio cells dividend (expense) income (1) 28 (1,174 ) — (1,229 ) — (2,375 ) Interest expense — — — (4,133 ) — (4,133 ) Income tax benefit (expense) — — 7 1,217 — 1,224 Segment operating results $ 13,313 $ 2,913 $ (359 ) $ 25,588 $ — $ 41,455 Significant non-cash items: Depreciation and amortization, net of accretion $ 1,911 $ 837 $ (3 ) $ 5,058 $ — $ 7,803 Three Months Ended March 31, 2016 (In thousands) Specialty P&C Workers' Compensation Lloyd's Syndicate Corporate Inter-segment Eliminations Consolidated Net premiums earned $ 110,755 $ 54,383 $ 12,441 $ — $ — $ 177,579 Net investment income — — 315 25,125 — 25,440 Equity in earnings (loss) of unconsolidated subsidiaries — — — (3,634 ) — (3,634 ) Net realized gains (losses) — — (5 ) (8,347 ) — (8,352 ) Other income 1,276 471 252 458 (103 ) 2,354 Net losses and loss adjustment expenses (2) (71,174 ) (35,027 ) (6,189 ) — 1,435 (110,955 ) Underwriting, policy acquisition and operating expenses (2) (25,054 ) (17,829 ) (5,167 ) (7,507 ) (1,332 ) (56,889 ) Segregated portfolio cells dividend (expense) income (1) — (713 ) — (463 ) — (1,176 ) Interest expense — — — (3,686 ) — (3,686 ) Income tax benefit (expense) — — (84 ) (1,280 ) — (1,364 ) Segment operating results $ 15,803 $ 1,285 $ 1,563 $ 666 $ — $ 19,317 Significant non-cash items: Depreciation and amortization, net of accretion $ 2,011 $ 1,404 $ 66 $ 5,149 $ — $ 8,630 (1) During the first quarter of 2017, ProAssurance began reporting in the Corporate segment the portion of the SPC dividend (expense) income that is attributable to the investment results of the SPCs, all of which are reported in the Corporate segment, to better align the expense with the related investment results of the SPCs. For comparative purposes, ProAssurance has reflected the SPC dividend expense for 2016 in the same manner. (2) In the first quarter of 2016, the portion of the management fee that was allocated to ULAE was eliminated in consolidation. During the second quarter of 2016, ProAssurance discontinued the practice of eliminating in consolidation the portion of the management fee that was allocated to ULAE, thus there was no similar elimination in the first quarter of 2017.
Schedule of Gross Premiums by Product	The following table provides detailed information regarding ProAssurance's gross premiums earned by product as well as a reconciliation to net premiums earned. All gross premiums earned are from external customers except as noted. ProAssurance's insured risks are primarily within the U.S. Three Months Ended March 31 (In thousands) 2017 2016 Specialty P&C Segment Gross premiums earned: Healthcare professional liability $ 117,051 $ 113,749 Legal professional liability 6,317 6,614 Medical technology liability 8,312 8,550 Other 102 268 Ceded premiums earned (18,724 ) (18,426 ) Segment net premiums earned 113,058 110,755 Workers' Compensation Segment Gross premiums earned: Traditional business 41,768 42,650 Alternative market business 19,446 18,294 Ceded premiums earned (5,931 ) (6,561 ) Segment net premiums earned 55,283 54,383 Lloyd's Syndicate Segment Gross premiums earned: Property and casualty* 17,185 13,373 Ceded premiums earned (2,623 ) (932 ) Segment net premiums earned 14,562 12,441 Consolidated Net premiums earned $ 182,903 $ 177,579 *Includes premium assumed from the Specialty P&C segment of $3.5 million for the three months ended March 31, 2017 and $3.6 million for the three months ended March 31, 2016 .

Basis of Presentation (Details

Basis of Presentation (Details Textual) $ in Thousands		3 Months Ended
		Mar. 31, 2017USD ($)segment	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments | segment		4
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unrecognized excess tax benefits recognized as current tax expense		$ 2,300
Operating activities in Condensed Consolidated Statements of Cash Flow		58,479	$ 56,982
Financing activities in Condensed Consolidated Statements of Cash Flow		(270,482)	$ (68,935)
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment- ASU 2016-09 adoption	[1]			$ 149
Operating activities in Condensed Consolidated Statements of Cash Flow		2,300
Financing activities in Condensed Consolidated Statements of Cash Flow		$ (2,300)
Additional Paid-in Capital [Member] | Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment- ASU 2016-09 adoption	[1]			425
Retained Earnings [Member] | Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment- ASU 2016-09 adoption	[1]			$ (276)
[1]	See Note 1 of the Notes to Condensed Consolidated Financial Statements for discussion of accounting guidance adopted during the period.

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SPC dividends payable	$ 37,002	$ 34,289
Unpaid dividends	16,516	265,659	$ 16,445
All other	116,799	122,336
Total other liabilities	$ 170,317	$ 422,285

Fair Value Measurement (Assets

Fair Value Measurement (Assets and Liabilities Measured at Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets:
Equity securities	$ 391,206	$ 387,274
Other investments	80,576	81,892
LP/LLC interests carried at NAV which approximates fair value. These interests, reported as a part of Investment in unconsolidated subsidiaries, are not categorized within the fair value hierarchy.	199,696	204,719
Level 3 [Member] | Corporate debt with limited observable inputs [Member]
Assets:
Total assets categorized within the fair value hierarchy	18,914	14,810
Level 3 [Member] | Other asset-backed securities [Member]
Assets:
Total assets categorized within the fair value hierarchy	3,002	3,007
Fair Value, Measurements, Recurring [Member]
Assets:
Other investments	29,978	31,501
Total assets categorized within the fair value hierarchy	3,305,954	3,474,265
LP/LLC interests carried at NAV which approximates fair value. These interests, reported as a part of Investment in unconsolidated subsidiaries, are not categorized within the fair value hierarchy.	199,696	204,719
Total assets at fair value, including NAV value not within fair value hierarchy	3,505,650	3,678,984
Fair Value, Measurements, Recurring [Member] | U.S. Treasury obligations [Member]
Assets:
Fixed maturities, available for sale	148,211	146,539
Fair Value, Measurements, Recurring [Member] | U.S. Government-sponsored enterprise obligations [Member]
Assets:
Fixed maturities, available for sale	28,701	30,235
Fair Value, Measurements, Recurring [Member] | State and municipal bonds [Member]
Assets:
Fixed maturities, available for sale	770,061	800,463
Fair Value, Measurements, Recurring [Member] | Corporate debt, multiple observable inputs [Member]
Assets:
Fixed maturities, available for sale	1,287,059	1,264,181
Fair Value, Measurements, Recurring [Member] | Corporate debt with limited observable inputs [Member]
Assets:
Fixed maturities, available for sale	18,914	14,810
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	207,906	217,906
Fair Value, Measurements, Recurring [Member] | Agency commercial mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	12,688	12,783
Fair Value, Measurements, Recurring [Member] | Other commercial mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	19,697	19,611
Fair Value, Measurements, Recurring [Member] | Other asset-backed securities [Member]
Assets:
Fixed maturities, available for sale	111,192	106,878
Fair Value, Measurements, Recurring [Member] | Financial [Member]
Assets:
Equity securities	84,052	81,749
Fair Value, Measurements, Recurring [Member] | Utilities/Energy [Member]
Assets:
Equity securities	51,304	52,869
Fair Value, Measurements, Recurring [Member] | Consumer oriented [Member]
Assets:
Equity securities	60,686	61,284
Fair Value, Measurements, Recurring [Member] | Industrial [Member]
Assets:
Equity securities	52,497	54,265
Fair Value, Measurements, Recurring [Member] | Bond funds [Member]
Assets:
Equity securities	92,753	90,002
Fair Value, Measurements, Recurring [Member] | All other [Member]
Assets:
Equity securities	49,914	47,105
Fair Value, Measurements, Recurring [Member] | Short-term investments [Member]
Assets:
Short-term investments	280,341	442,084
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Assets:
Other investments	1,270	1,956
Total assets categorized within the fair value hierarchy	672,365	799,066
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. Treasury obligations [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. Government-sponsored enterprise obligations [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | State and municipal bonds [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate debt, multiple observable inputs [Member]
Assets:
Fixed maturities, available for sale	2,395	2,339
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate debt with limited observable inputs [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Residential mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Agency commercial mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other commercial mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other asset-backed securities [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Financial [Member]
Assets:
Equity securities	84,052	81,749
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Utilities/Energy [Member]
Assets:
Equity securities	51,304	52,869
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Consumer oriented [Member]
Assets:
Equity securities	60,686	61,284
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Industrial [Member]
Assets:
Equity securities	52,497	54,265
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Bond funds [Member]
Assets:
Equity securities	92,753	79,843
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | All other [Member]
Assets:
Equity securities	49,914	27,181
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Short-term investments [Member]
Assets:
Short-term investments	277,494	437,580
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Assets:
Other investments	27,805	29,542
Total assets categorized within the fair value hierarchy	2,610,770	2,657,379
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Treasury obligations [Member]
Assets:
Fixed maturities, available for sale	148,211	146,539
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Government-sponsored enterprise obligations [Member]
Assets:
Fixed maturities, available for sale	28,701	30,235
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | State and municipal bonds [Member]
Assets:
Fixed maturities, available for sale	770,061	800,463
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate debt, multiple observable inputs [Member]
Assets:
Fixed maturities, available for sale	1,284,664	1,261,842
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate debt with limited observable inputs [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Residential mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	207,906	217,906
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Agency commercial mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	12,688	12,783
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other commercial mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	19,697	19,611
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other asset-backed securities [Member]
Assets:
Fixed maturities, available for sale	108,190	103,871
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Financial [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Utilities/Energy [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Consumer oriented [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Industrial [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Bond funds [Member]
Assets:
Equity securities	0	10,159
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | All other [Member]
Assets:
Equity securities	0	19,924
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Short-term investments [Member]
Assets:
Short-term investments	2,847	4,504
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Assets:
Other investments	903	3
Total assets categorized within the fair value hierarchy	22,819	17,820
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | U.S. Treasury obligations [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | U.S. Government-sponsored enterprise obligations [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | State and municipal bonds [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate debt, multiple observable inputs [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate debt with limited observable inputs [Member]
Assets:
Fixed maturities, available for sale	18,914	14,810
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Residential mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Agency commercial mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other commercial mortgage-backed securities [Member]
Assets:
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other asset-backed securities [Member]
Assets:
Fixed maturities, available for sale	3,002	3,007
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Financial [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Utilities/Energy [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Consumer oriented [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Industrial [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Bond funds [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | All other [Member]
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Short-term investments [Member]
Assets:
Short-term investments	$ 0	$ 0

Fair Value Measurement (Quantit

Fair Value Measurement (Quantitative Information Regarding Level 3 Valuations) (Details) - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Corporate debt with limited observable inputs [Member]
Assets:
Fair Value at	$ 18,914	$ 14,810
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	5.00%
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	2.50%
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	5.00%
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	2.50%
Other asset-backed securities [Member]
Assets:
Fair Value at	$ 3,002	3,007
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	5.00%
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	2.50%
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	5.00%
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	2.50%
Other investments [Member]
Assets:
Fair Value at	$ 903	$ 3
Other investments [Member] | Discount cash flows valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Other investments [Member] | Discount cash flows valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	10.00%
Other investments [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	5.00%

Fair Value Measurement (Level 3

Fair Value Measurement (Level 3 Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	$ 17,820	$ 15,257
Included in earnings, as a part of:
Included in other comprehensive income	(211)	(78)
Purchases	7,048	5,060
Sales	(1,712)	(848)
Transfers in	898	0
Transfers out	(998)	(6)
Ending Balance	22,819	19,295
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0
Corporate debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	14,810	14,500
Included in earnings, as a part of:
Included in other comprehensive income	(208)	(75)
Purchases	7,048	0
Sales	(1,712)	(681)
Transfers in	0	0
Transfers out	(998)	(6)
Ending Balance	18,914	13,649
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0
Asset-backed securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	3,007	757
Included in earnings, as a part of:
Included in other comprehensive income	(5)	(2)
Purchases	0	3,500
Sales	0	(167)
Transfers in	0	0
Transfers out	0	0
Ending Balance	3,002	4,088
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0
All other investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	3	0
Included in earnings, as a part of:
Included in other comprehensive income	2	(1)
Purchases	0	1,560
Sales	0	0
Transfers in	898	0
Transfers out	0	0
Ending Balance	903	1,558
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0
Net investment Income [Member]
Included in earnings, as a part of:
Total gains (losses) realized and unrealized, included in earnings	(39)	(15)
Net investment Income [Member] | Corporate debt [Member]
Included in earnings, as a part of:
Total gains (losses) realized and unrealized, included in earnings	(39)	(14)
Net investment Income [Member] | Asset-backed securities [Member]
Included in earnings, as a part of:
Total gains (losses) realized and unrealized, included in earnings	0	0
Net investment Income [Member] | All other investments [Member]
Included in earnings, as a part of:
Total gains (losses) realized and unrealized, included in earnings	0	(1)
Net realized investment gains (losses) [Member]
Included in earnings, as a part of:
Total gains (losses) realized and unrealized, included in earnings	13	(75)
Net realized investment gains (losses) [Member] | Corporate debt [Member]
Included in earnings, as a part of:
Total gains (losses) realized and unrealized, included in earnings	13	(75)
Net realized investment gains (losses) [Member] | Asset-backed securities [Member]
Included in earnings, as a part of:
Total gains (losses) realized and unrealized, included in earnings	0	0
Net realized investment gains (losses) [Member] | All other investments [Member]
Included in earnings, as a part of:
Total gains (losses) realized and unrealized, included in earnings	$ 0	$ 0

Fair Value Measurement (Narrati

Fair Value Measurement (Narrative) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2017USD ($)Agreement	Dec. 31, 2016USD ($)
Credit Derivatives [Line Items]
Number of line of credit agreement | Agreement	2
Equity securities [Member]
Credit Derivatives [Line Items]
Transfer of equity securities from Level 2 to Level 1 | $	$ 35,400,000	$ 0
Standard & Poor's, BBB Rating [Member] | Corporate debt with limited observable inputs [Member]
Credit Derivatives [Line Items]
Credit rating	88.00%
NRSRO | Standard & Poor's, BBB+ Rating [Member] | Corporate debt with limited observable inputs [Member]
Credit Derivatives [Line Items]
Credit rating		84.00%

Fair Value Measurement (Investm

Fair Value Measurement (Investments in LLCs and Limited Partnerships) (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments in LPs/LLCs fair value	$ 199,696,000	$ 204,719,000
Private debt fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments LPs/LLCs unfunded commitments	11,972,000
Investments in LPs/LLCs fair value	51,307,000	55,637,000
Long equity fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments LPs/LLCs unfunded commitments	0
Investments in LPs/LLCs fair value	6,770,000	6,268,000
Long/Short equity funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments LPs/LLCs unfunded commitments	0
Investments in LPs/LLCs fair value	29,944,000	28,926,000
Non-public equity funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments LPs/LLCs unfunded commitments	55,334,000
Investments in LPs/LLCs fair value	86,506,000	89,691,000
Multi-strategy fund of funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments LPs/LLCs unfunded commitments	0
Investments in LPs/LLCs fair value	8,668,000	8,448,000
Structured credit fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments LPs/LLCs unfunded commitments	0
Investments in LPs/LLCs fair value	4,466,000	4,273,000
Long/Short commodities fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments LPs/LLCs unfunded commitments	0
Investments in LPs/LLCs fair value	$ 12,035,000	$ 11,476,000

Fair Value Measurement (Inves35

Fair Value Measurement (Investments in LLCs and Limited Partnerships Footnote) (Details)	3 Months Ended
	Mar. 31, 2017
Long equity fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investment redemption notice period	15 days
Payment period for redemption of LP valued at NAV	10 days
Long/Short Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Payment period for redemption of LP valued at NAV	30 days
Redemption percentage of LP at NAV for which initial payment is limited	90.00%
Non-public equity funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidating investments remaining period	9 years
Structured credit fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investment redemption notice period	90 days
Long/Short commodities fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investment redemption notice period	30 days
Minimum [Member] | Secured debt fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidating investments remaining period	3 years
Minimum [Member] | Long/Short Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investment redemption notice period	30 days
Maximum [Member] | Secured debt fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidating investments remaining period	8 years
Maximum [Member] | Long/Short Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investment redemption notice period	90 days
Maximum [Member] | Long/Short commodities fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Payment period for redemption of LP valued at NAV	30 days

Fair Value Measurement (Methodo

Fair Value Measurement (Methodologies Other Than Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financial assets:
BOLI	$ 60,589	$ 60,134
Other investments	80,576	81,892
Other assets	101,589	96,004
Financial liabilities:
Debt	448,288	448,202
Total other liabilities	170,317	422,285
Not Measured At Fair Value [Member] | Carrying Value [Member]
Financial assets:
BOLI	60,589	60,134
Other investments	50,598	50,391
Other assets	29,196	29,111
Financial liabilities:
Total other liabilities	17,855	17,033
Not Measured At Fair Value [Member] | Carrying Value [Member] | Senior notes due 2023 [Member]
Financial liabilities:
Debt	250,000	250,000
Not Measured At Fair Value [Member] | Carrying Value [Member] | Revolving Credit Facility [Member]
Financial liabilities:
Debt	200,000	200,000
Not Measured At Fair Value [Member] | Level 3 [Member] | Fair Value [Member]
Financial assets:
BOLI	60,589	60,134
Other investments	62,061	58,757
Other assets	29,072	28,960
Financial liabilities:
Total other liabilities	17,855	17,011
Not Measured At Fair Value [Member] | Level 3 [Member] | Fair Value [Member] | Senior notes due 2023 [Member]
Financial liabilities:
Debt	274,315	270,898
Not Measured At Fair Value [Member] | Level 3 [Member] | Fair Value [Member] | Revolving Credit Facility [Member]
Financial liabilities:
Debt	$ 200,000	$ 200,000

Investments (Available-For-Sale

Investments (Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
U.S. Treasury obligations [Member]
Fixed maturities, available for sale
Amortized Cost	$ 147,826	$ 146,186
Gross Unrealized Gains	1,203	1,264
Gross Unrealized Losses	818	911
Estimated Fair Value	148,211	146,539
U.S. Government-sponsored enterprise obligations [Member]
Fixed maturities, available for sale
Amortized Cost	28,621	30,038
Gross Unrealized Gains	241	388
Gross Unrealized Losses	161	191
Estimated Fair Value	28,701	30,235
State and municipal bonds [Member]
Fixed maturities, available for sale
Amortized Cost	755,639	790,154
Gross Unrealized Gains	19,139	17,261
Gross Unrealized Losses	4,717	6,952
Estimated Fair Value	770,061	800,463
Corporate debt [Member]
Fixed maturities, available for sale
Amortized Cost	1,291,140	1,264,812
Gross Unrealized Gains	21,812	22,659
Gross Unrealized Losses	6,979	8,480
Estimated Fair Value	1,305,973	1,278,991
Residential mortgage-backed securities [Member]
Fixed maturities, available for sale
Amortized Cost	206,455	216,285
Gross Unrealized Gains	3,407	3,667
Gross Unrealized Losses	1,956	2,046
Estimated Fair Value	207,906	217,906
Agency commercial mortgage-backed securities [Member]
Fixed maturities, available for sale
Amortized Cost	12,727	12,837
Gross Unrealized Gains	63	89
Gross Unrealized Losses	102	143
Estimated Fair Value	12,688	12,783
Other commercial mortgage-backed securities [Member]
Fixed maturities, available for sale
Amortized Cost	19,650	19,571
Gross Unrealized Gains	153	177
Gross Unrealized Losses	106	137
Estimated Fair Value	19,697	19,611
Other asset-backed securities [Member]
Fixed maturities, available for sale
Amortized Cost	111,214	106,938
Gross Unrealized Gains	191	207
Gross Unrealized Losses	213	267
Estimated Fair Value	111,192	106,878
Debt Securities [Member]
Fixed maturities, available for sale
Amortized Cost	2,573,272	2,586,821
Gross Unrealized Gains	46,209	45,712
Gross Unrealized Losses	15,052	19,127
Estimated Fair Value	$ 2,604,429	$ 2,613,406

Investments (Available For Sale

Investments (Available For Sale Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
U.S. Treasury obligations [Member]
Fixed maturities, available for sale
Amortized Cost	$ 147,826	$ 146,186
Due in one year or less	28,876
Due after one year through five years	98,304
Due after five years through ten years	18,042
Due after ten years	2,989
Estimated Fair Value	148,211	146,539
U.S. Government-sponsored enterprise obligations [Member]
Fixed maturities, available for sale
Amortized Cost	28,621	30,038
Due in one year or less	12,863
Due after one year through five years	7,781
Due after five years through ten years	7,918
Due after ten years	139
Estimated Fair Value	28,701	30,235
State and municipal bonds [Member]
Fixed maturities, available for sale
Amortized Cost	755,639	790,154
Due in one year or less	66,017
Due after one year through five years	264,597
Due after five years through ten years	348,641
Due after ten years	90,806
Estimated Fair Value	770,061	800,463
Corporate debt [Member]
Fixed maturities, available for sale
Amortized Cost	1,291,140	1,264,812
Due in one year or less	122,549
Due after one year through five years	764,626
Due after five years through ten years	388,119
Due after ten years	30,679
Estimated Fair Value	1,305,973	1,278,991
Residential mortgage-backed securities [Member]
Fixed maturities, available for sale
Amortized Cost	206,455	216,285
Estimated Fair Value	207,906	217,906
Agency commercial mortgage-backed securities [Member]
Fixed maturities, available for sale
Amortized Cost	12,727	12,837
Estimated Fair Value	12,688	12,783
Other commercial mortgage-backed securities [Member]
Fixed maturities, available for sale
Amortized Cost	19,650	19,571
Estimated Fair Value	19,697	19,611
Other asset-backed securities [Member]
Fixed maturities, available for sale
Amortized Cost	111,214	106,938
Estimated Fair Value	111,192	106,878
Debt Securities [Member]
Fixed maturities, available for sale
Amortized Cost	2,573,272	2,586,821
Estimated Fair Value	$ 2,604,429	$ 2,613,406

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)AffiliateBusinessIssuerinvestment_interestSecurity	Mar. 31, 2016USD ($)Issuer	Dec. 31, 2016USD ($)IssuerSecurity	Dec. 31, 2015USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of investment affiliates exceeding shareholder's equity ten percent threshold limit | Affiliate	0
Threshold limit of investments based on shareholders' equity	10.00%
Securities on deposit with state insurance departments	$ 46,400
Business owned life insurance cost	33,000
Investment in unconsolidated subsidiaries	330,479		$ 340,906
Investments in LPs/LLCs fair value	$ 199,696		204,719
Number of LPs / LLCs with investment ownership percent over 25% | Business	3
Equity in earnings, losses from affordable housing projects	$ (3,300)	$ (5,200)
Affordable housing tax credits	4,600	4,600
Losses from historic tax credit investments	(400)	(200)
Tax credits recognized related to historic tax credit investments	1,800	2,600
Net impairment losses recognized in earnings	171	9,666
Portion of noncredit OTTI losses recognized in OCI	248	1,068
Credit-related other-than-temporary impairment recognized in earnings	$ 1,329	6,559	1,158	$ 5,751
Tax Credit Partnerships Almost 100% Ownership [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of tax credit partnerships almost 100% ownership percentage | investment_interest	2
Investment in unconsolidated subsidiaries	$ 38,300		40,200
Tax Credit Partnerships Less Than 20% Ownership [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment in unconsolidated subsidiaries	60,700		62,100
Other Limited Partnerships and Limited Liability Company, Not Considered Investment Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment in unconsolidated subsidiaries	$ 20,700		22,400
Other Limited Partnerships and Limited Liability Company, Greater Than 25% Ownership [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity method investment ownership percentage	25.00%
Investment in unconsolidated subsidiaries	$ 20,800		18,500
Other Limited Partnerships and Limited Liability Company Less than 25% Ownership [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment in unconsolidated subsidiaries	$ 199,600		$ 208,600
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Period for federal home loan bank stock liquidation process	5 years
Maximum [Member] | Tax Credit Partnerships Almost 100% Ownership [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity method investment ownership percentage	100.00%
Maximum [Member] | Tax Credit Partnerships Less Than 20% Ownership [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity method investment ownership percentage	20.00%
Fixed maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Required FAL Deposit	$ 96,700
Short-term investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Required FAL Deposit	$ 1,000
Non Government-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of debt securities in unrealized loss position | Security	587		703
Debt securities in unrealized loss position as percentage of total debt securities held	23.20%		27.20%
Number of issuers in unrealized loss position | Issuer	397		456
Single greatest unrealized loss position	$ 500		$ 500
Second greatest unrealized loss position	400		500
Corporate debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Portion of noncredit OTTI losses recognized in OCI	248	$ 1,068
Credit-related other-than-temporary impairment recognized in earnings			$ 5,500
Debt securities, number of issuers | Issuer		10
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Net impairment losses recognized in earnings		$ 6,500
Portion of noncredit OTTI losses recognized in OCI		900
Other investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Net impairment losses recognized in earnings		$ 3,100
Revolving Credit Facility [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities pledged as collateral	$ 246,500

Investments (Unconsolidated Sub

Investments (Unconsolidated Subsidiaries) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Unconsolidated Subsidiaries
Investment in unconsolidated subsidiaries	$ 330,479	$ 340,906
Qualified affordable housing tax credit partnerships [Member]
Unconsolidated Subsidiaries
Investment in unconsolidated subsidiaries	99,005	102,313
Other tax credit partnerships [Member]
Unconsolidated Subsidiaries
Investment in unconsolidated subsidiaries	11,041	11,459
All Other LPs/LLCs [Member]
Unconsolidated Subsidiaries
Investment in unconsolidated subsidiaries	$ 220,433	$ 227,134

Investments (Other Investments)

Investments (Other Investments) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Other Investments
Other investments	$ 80,576	$ 81,892
Investments in LPs/LLCs, at cost [Member]
Other Investments
Other investments	47,164	46,852
Convertible securities, at fair value [Member]
Other Investments
Other investments	29,978	31,501
Other, principally FHLB capital stock at cost [Member]
Other Investments
Other investments	$ 3,434	$ 3,539

Investments (Investments Held i

Investments (Investments Held in a Loss Position) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
U.S. Treasury obligations [Member]
Investments held in an unrealized loss position
Fair Value	$ 82,630	$ 79,833
Unrealized Loss	818	911
Less than 12 months, Fair Value	82,630	79,833
Less than 12 months, Unrealized Loss	818	911
More than 12 months, Fair Value	0	0
More than 12 months, Unrealized Loss	0	0
US Government-sponsored Enterprises Debt Securities [Member]
Investments held in an unrealized loss position
Fair Value	10,507	11,746
Unrealized Loss	161	191
Less than 12 months, Fair Value	10,507	11,746
Less than 12 months, Unrealized Loss	161	191
More than 12 months, Fair Value	0	0
More than 12 months, Unrealized Loss	0	0
State and municipal bonds [Member]
Investments held in an unrealized loss position
Fair Value	167,434	224,884
Unrealized Loss	4,717	6,952
Less than 12 months, Fair Value	160,343	219,276
Less than 12 months, Unrealized Loss	4,132	6,444
More than 12 months, Fair Value	7,091	5,608
More than 12 months, Unrealized Loss	585	508
Corporate debt [Member]
Investments held in an unrealized loss position
Fair Value	416,640	469,632
Unrealized Loss	6,979	8,480
Less than 12 months, Fair Value	382,246	424,721
Less than 12 months, Unrealized Loss	4,361	5,662
More than 12 months, Fair Value	34,394	44,911
More than 12 months, Unrealized Loss	2,618	2,818
Residential mortgage-backed securities [Member]
Investments held in an unrealized loss position
Fair Value	97,495	103,680
Unrealized Loss	1,956	2,046
Less than 12 months, Fair Value	95,381	100,542
Less than 12 months, Unrealized Loss	1,922	1,982
More than 12 months, Fair Value	2,114	3,138
More than 12 months, Unrealized Loss	34	64
Agency commercial mortgage-backed securities [Member]
Investments held in an unrealized loss position
Fair Value	4,571	4,579
Unrealized Loss	102	143
Less than 12 months, Fair Value	4,191	4,192
Less than 12 months, Unrealized Loss	72	114
More than 12 months, Fair Value	380	387
More than 12 months, Unrealized Loss	30	29
Other commercial mortgage-backed securities [Member]
Investments held in an unrealized loss position
Fair Value	10,890	9,822
Unrealized Loss	106	137
Less than 12 months, Fair Value	9,075	9,179
Less than 12 months, Unrealized Loss	85	134
More than 12 months, Fair Value	1,815	643
More than 12 months, Unrealized Loss	21	3
Other asset-backed securities [Member]
Investments held in an unrealized loss position
Fair Value	46,008	44,343
Unrealized Loss	213	267
Less than 12 months, Fair Value	42,018	39,079
Less than 12 months, Unrealized Loss	207	256
More than 12 months, Fair Value	3,990	5,264
More than 12 months, Unrealized Loss	6	11
Debt Securities [Member]
Investments held in an unrealized loss position
Fair Value	836,175	948,519
Unrealized Loss	15,052	19,127
Less than 12 months, Fair Value	786,391	888,568
Less than 12 months, Unrealized Loss	11,758	15,694
More than 12 months, Fair Value	49,784	59,951
More than 12 months, Unrealized Loss	$ 3,294	$ 3,433

Investments (Net Investment Inc

Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net Investment Income
Investment fees and expenses	$ (1,835)	$ (1,643)
Net investment income	23,186	25,440
Fixed maturities [Member]
Net Investment Income
Investment Income	20,121	22,575
Equities [Member]
Net Investment Income
Investment Income	3,644	3,643
Short-term investments and Other invested assets [Member]
Net Investment Income
Investment Income	801	405
BOLI [Member]
Net Investment Income
Investment Income	$ 455	$ 460

Investments (Net Realized Inves

Investments (Net Realized Investment Gains (Losses)) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)Issuer	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Gain (Loss) on Investments [Line Items]
OTTI losses	$ (419)	$ (10,734)
Portion of OTTI losses recognized in other comprehensive income before taxes	248	1,068
Net impairment losses recognized in earnings	(171)	(9,666)
Gross realized gains, available-for-sale securities	1,853	3,185
Gross realized (losses), available-for-sale securities	(67)	(4,647)
Net realized gains (losses), trading securities	6,562	2,055
Net realized gains (losses), Other investments	1,172	52
Change in unrealized holding gains (losses), trading securities	3,616	733
Change in unrealized holding gains (losses), convertible securities, carried at fair value	313	(66)
Other	2	2
Total net realized investment gains (losses)	13,280	(8,352)
Credit-related other-than-temporary impairment recognized in earnings	1,329	6,559	$ 1,158	$ 5,751
Corporate debt [Member]
Gain (Loss) on Investments [Line Items]
OTTI losses	(419)	(7,604)
Portion of OTTI losses recognized in other comprehensive income before taxes	248	$ 1,068
Credit-related other-than-temporary impairment recognized in earnings			$ 5,500
Debt securities, number of issuers | Issuer		10
Other investments [Member]
Gain (Loss) on Investments [Line Items]
OTTI losses	$ 0	$ (3,130)
Net impairment losses recognized in earnings		$ (3,100)

Investments (Credit Losses Reco

Investments (Credit Losses Recorded in Earnings) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other than Temporary Impairment, Credit Losses Recognized in Earnings:
Accumulated credit losses related to impaired debt securities, Beginning Balance	$ 1,158	$ 5,751
No OTTI has been previously recognized	171	2,398
OTTI has been previously recognized	0	2,154
Securities sold during the period (realized)	0	(3,744)
Accumulated credit losses related to impaired debt securities, Ending Balance	$ 1,329	$ 6,559

Investments (Sales and Purchase

Investments (Sales and Purchases of Available-for-Sale Securities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Information regarding sales and purchases of available-for-sale securities
Proceeds from sales (exclusive of maturities and paydowns)	$ 79,200	$ 109,900
Purchases	$ 160,364	$ 199,590

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 8.4	$ 8.4
Other Assets [Member]
Income Tax Contingency [Line Items]
Income taxes receivable	$ 3.3
Other Liabilities [Member]
Income Tax Contingency [Line Items]
Income taxes liabilities		$ 5.1

Deferred Policy Acquisition C48

Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Insurance [Abstract]
Amortization of deferred policy acquisition costs	$ 22.6	$ 21.5

Reserve for Losses and Loss A49

Reserve for Losses and Loss Adjustment Expenses - Narrative and Activity in the Reserve (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017USD ($)partition	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)
Liability for Unpaid Claims and Claims Adjustment Expense, Period Increase (Decrease) [Abstract]
Minimum period for claims resolution (years)	5 years
Number of business partitions | partition	219
Summary of reserve for losses and loss adjustment expenses
Balance, beginning of year	$ 1,993,428	$ 2,005,326	$ 2,005,326
Less reinsurance recoverables on unpaid losses and loss adjustment expenses	273,475	249,350	249,350
Net balance, beginning of year	1,719,953	1,755,976	1,755,976
Net reserves acquired from acquisitions	0	0	0
Net losses:
Current year	147,927	139,660	587,007
Favorable development of reserves established in prior years, net	(28,776)	(28,705)	(143,778)
Total	119,151	110,955	443,229
Paid related to:
Current year	(33,085)	(26,411)	(96,190)
Prior years	(80,709)	(80,154)	(383,062)
Total paid	(113,794)	(106,565)	(479,252)
Net balance, end of year	1,725,310	1,760,367	1,719,953
Plus reinsurance recoverables on unpaid losses and loss adjustment expenses	271,679	245,403	273,475
Balance, end of year	$ 1,996,989	$ 2,005,770	$ 1,993,428

Commitments and Contingencies (

Commitments and Contingencies (Narrative) (Details)	Mar. 31, 2017USD ($)	Mar. 31, 2017GBP (£)	Apr. 30, 2016GBP (£)
Non-Public Investment Entities [Member]
Other Commitment, Fiscal Year Maturity [Abstract]
Commitments Total	$ 138,400,000
Commitments due 2017	55,300,000
Commitments due 2018 and 2019	52,800,000
Commitments due 2020 and 2021	25,400,000
Commitments due thereafter	4,900,000
Qualified Affordable Housing Project [Member]
Other Commitment, Fiscal Year Maturity [Abstract]
Commitments due 2017	300,000
Commitments due 2018 and 2019	300,000
Commitments due 2020 and 2021	300,000
Commitments due thereafter	500,000
Qualified affordable housing project investments	1,400,000
Strategic Business Partnership [Member]
Other Commitment, Fiscal Year Maturity [Abstract]
Line of credit amount	9,000,000
Line of credit unused commitment	4,900,000
Lloyds Syndicate [Member]
Other Commitment, Fiscal Year Maturity [Abstract]
Required FAL Deposit	97,700,000
Current lending capacity under revolving credit agreement | £			£ 20,000,000
Interest rate on revolving credit agreement			3.80%
Unused commitments to extend credit	15,600,000	£ 12,400,000
Lloyds Syndicate [Member] | Commitment to Provide Capital [Member]
Other Commitment, Fiscal Year Maturity [Abstract]
Commitments Total	$ 200,000,000

Debt (Details)

Debt (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Outstanding long-term debt
Debt, gross	$ 450,000,000	$ 450,000,000
Less debt issuance costs	1,712,000	1,798,000
Debt less debt issuance costs	448,288,000	448,202,000
Senior Notes [Member] | Senior notes due 2023 [Member]
Outstanding long-term debt
Debt, gross	$ 250,000,000	$ 250,000,000
Debt stated interest rate	5.30%	5.30%
Line of Credit [Member] | Revolving Credit Facility [Member]
Outstanding long-term debt
Debt, gross	$ 200,000,000	$ 200,000,000
Interest rate on senior notes	1.44%	1.35%
Line of credit maximum borrowing capacity	$ 250,000,000	$ 250,000,000

Shareholders' Equity (Narrative

Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 28, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized common stock (in shares)		100,000,000		100,000,000
Authorized preferred stock (in shares)		50,000,000		50,000,000
Quarterly dividend declared, per share (USD per share)		$ 0.31	$ 0.31
Dividend declared		$ 16,500	$ 16,400
Total authorizations which remain available for use		$ 109,600
Common shares acquired (in shares)		0	27,700
Cost of common shares reacquired		$ 0	$ 1,301
Share-based compensation expense		3,346	2,715
Share-based compensation		3,346	2,715
Tax benefits from share-based compensation expense		1,171	950
Bonus compensation shares issued (in shares)	9,000
Gain (loss) related to unrecognized changes in defined benefit plan liabilities			$ 300
Non-credit loss, net of tax		$ 500		$ 300
Statutory income tax rate		35.00%		35.00%
Restricted Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards in period (in shares)	84,600
Fair value of each unit awarded (USD per share)	$ 58.35
Award vesting period	3 years
Shares issued in period for share-based compensation (in shares)	29,300
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards in period (in shares)	48,000
Shares issued in period for share-based compensation (in shares)	99,500
Minimum [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award payout rate	50.00%
Minimum [Member] | Performance Shares Granted in 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award payout rate					117.00%
Maximum [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award payout rate	200.00%
Maximum [Member] | Performance Shares Granted in 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award payout rate					125.00%

Shareholders' Equity (Share-bas

Shareholders' Equity (Share-based Compensation Expense and Related Tax Benefits) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Equity [Abstract]
Share-based compensation expense	$ 3,346	$ 2,715
Related tax benefits	$ 1,171	$ 950

Shareholders' Equity (AOCI Recl

Shareholders' Equity (AOCI Reclassification) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Reclassifications from AOCI to Net income:
Deferred tax expense (benefit) included in OCI	$ 1,481	$ 12,260
Tax rate used to compute the tax effect of amounts reclassified out of OCI	35.00%		35.00%
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications from AOCI to Net income:
Reclassification amount, before tax effect	$ 1,616	(7,999)
Tax effect (at 35%)	(566)	2,800
Net reclassification adjustments	1,050	(5,199)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Realized investment gains (losses) [Member]
Reclassifications from AOCI to Net income:
Reclassification amount, before tax effect	1,616	(5,241)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Non-credit impairment losses reclassified to earnings, due to sale of securities or reclassification as a credit loss [Member]
Reclassifications from AOCI to Net income:
Reclassification amount, before tax effect	$ 0	$ (2,758)

Variable Interest Entities (Det

Variable Interest Entities (Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Other investments [Member]
Variable Interest Entity [Line Items]
VIE interests carrying value	$ 26.9	$ 26.9
Investment in unconsolidated subsidiaries [Member]
Variable Interest Entity [Line Items]
VIE interests carrying value	$ 270.7	$ 282.3

Segment Information (Narrative)

Segment Information (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)segment	Mar. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	4
Premiums ceded under quota share agreement | $	$ 3.5	$ 3.6
Workers Compensation [Member]
Segment Reporting Information [Line Items]
Worker's compensation SPC percentage ceded	100.00%
Lloyds Syndicate [Member]
Segment Reporting Information [Line Items]
Proportion of Capital Provided to support Lloyd's Syndicate 1729	58.00%

Segment Information (Financial

Segment Information (Financial Data by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Net premiums earned	$ 182,903	$ 177,579
Net investment income	23,186	25,440
Equity in earnings (loss) of unconsolidated subsidiaries	1,808	(3,634)
Net realized gains (losses)	13,280	(8,352)
Other income	1,821	2,354
Net losses and loss adjustment expenses	(119,151)	(110,955)
Underwriting, policy acquisition and operating expenses	(57,108)	(56,889)
Segregated portfolio cells dividend (expense) income	(2,375)	(1,176)
Interest expense	(4,133)	(3,686)
Income tax benefit (expense)	1,224	(1,364)
Net income	41,455	19,317
Depreciation and amortization, net of accretion	7,803	8,630
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segregated portfolio cells dividend (expense) income		(463)
Operating Segments [Member] | Specialty P&C [Member]
Segment Reporting Information [Line Items]
Net premiums earned	113,058	110,755
Other income	1,198	1,276
Net losses and loss adjustment expenses	(74,994)	(71,174)
Underwriting, policy acquisition and operating expenses	(25,977)	(25,054)
Segregated portfolio cells dividend (expense) income	28
Net income	13,313	15,803
Depreciation and amortization, net of accretion	1,911	2,011
Operating Segments [Member] | Workers Compensation [Member]
Segment Reporting Information [Line Items]
Net premiums earned	55,283	54,383
Other income	145	471
Net losses and loss adjustment expenses	(34,650)	(35,027)
Underwriting, policy acquisition and operating expenses	(16,691)	(17,829)
Segregated portfolio cells dividend (expense) income	(1,174)	(713)
Net income	2,913	1,285
Depreciation and amortization, net of accretion	837	1,404
Operating Segments [Member] | Lloyds Syndicate [Member]
Segment Reporting Information [Line Items]
Net premiums earned	14,562	12,441
Net investment income	372	315
Net realized gains (losses)	27	(5)
Other income	391	252
Net losses and loss adjustment expenses	(9,507)	(6,189)
Underwriting, policy acquisition and operating expenses	(6,211)	(5,167)
Income tax benefit (expense)	7	(84)
Net income	(359)	1,563
Depreciation and amortization, net of accretion	(3)	66
Operating Segments [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Net investment income	22,814	25,125
Equity in earnings (loss) of unconsolidated subsidiaries	1,808	(3,634)
Net realized gains (losses)	13,253	(8,347)
Other income	173	458
Underwriting, policy acquisition and operating expenses	(8,315)	(7,507)
Segregated portfolio cells dividend (expense) income	(1,229)
Interest expense	(4,133)	(3,686)
Income tax benefit (expense)	1,217	(1,280)
Net income	25,588	666
Depreciation and amortization, net of accretion	5,058	5,149
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net premiums earned	0	0
Other income	(86)	(103)
Net losses and loss adjustment expenses	0	1,435
Underwriting, policy acquisition and operating expenses	86	(1,332)
Net income	0	0
Depreciation and amortization, net of accretion	$ 0	$ 0

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Net premiums earned	$ 182,903	$ 177,579
Healthcare professional liability [Member] | Specialty P&C [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	117,051	113,749
Legal professional liability [Member] | Specialty P&C [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	6,317	6,614
Medical technology and life sciences product liability [Member] | Specialty P&C [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	8,312	8,550
Other [Member] | Specialty P&C [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	102	268
Traditional business [Member] | Workers Compensation [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	41,768	42,650
Alternative market business [Member] | Workers Compensation [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	19,446	18,294
Operating Segments [Member] | Specialty P&C [Member]
Segment Reporting Information [Line Items]
Ceded premiums earned	(18,724)	(18,426)
Net premiums earned	113,058	110,755
Operating Segments [Member] | Workers Compensation [Member]
Segment Reporting Information [Line Items]
Ceded premiums earned	(5,931)	(6,561)
Net premiums earned	55,283	54,383
Operating Segments [Member] | Lloyds Syndicate [Member]
Segment Reporting Information [Line Items]
Ceded premiums earned	(2,623)	(932)
Net premiums earned	14,562	12,441
Operating Segments [Member] | Property, Liability and Casualty Insurance Product Line [Member] | Lloyds Syndicate [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	$ 17,185	$ 13,373

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	1 Months Ended
	Apr. 30, 2017USD ($)
Subsequent event [Member] | Line of Credit [Member] | Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Amount of debt repaid	$ 10