ProAssurance (PRA) 10-Q 5 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 31, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'PROASSURANCE CORP	'
Entity Central Index Key	'0001127703	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	57,183,941
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments	'	'
Fixed maturities, available for sale, at fair value; amortized cost, $3,143,726 and $3,026,256, respectively	$3,246,820	$3,118,049
Equity securities, trading, at fair value; cost, $274,324 and $203,308, respectively	306,631	253,541
Short-term investments	94,973	248,605
Business owned life insurance	55,918	54,374
Investment in unconsolidated subsidiaries	254,962	214,236
Other investments, $30,058 at fair value at September 30, 2014, otherwise at cost or amortized cost	92,010	52,240
Total Investments	4,051,314	3,941,045
Cash and cash equivalents	248,005	129,383
Restricted cash	0	78,000
Premiums receivable	229,798	115,403
Receivable from reinsurers on paid losses and loss adjustment expenses	9,918	3,231
Receivable from reinsurers on unpaid losses and loss adjustment expenses	251,605	247,518
Prepaid reinsurance premiums	36,286	21,449
Deferred policy acquisition costs	44,049	28,207
Deferred tax asset	0	1,757
Real estate, net	40,116	41,010
Intangible assets	103,224	52,002
Goodwill	210,725	161,115
Other assets	100,957	329,979
Total Assets	5,325,997	5,150,099
Policy liabilities and accruals	'	'
Reserve for losses and loss adjustment expenses	2,146,018	2,072,822
Unearned premiums	391,296	255,463
Reinsurance premiums payable	32,314	34,321
Total Policy Liabilities	2,569,628	2,362,606
Deferred tax liability	21,062	0
Other liabilities	164,095	143,079
Long-term debt	250,000	250,000
Total Liabilities	3,004,785	2,755,685
Shareholders’ Equity	'	'
Common shares, par value $0.01 per share, 100,000,000 shares authorized, 62,283,426 and 62,096,787 shares issued, respectively	623	621
Additional paid-in capital	357,779	349,894
Accumulated other comprehensive income (loss), net of deferred tax expense (benefit) of $35,591 and $32,127, respectively	67,007	59,661
Retained earnings	2,094,181	2,015,603
Treasury shares, at cost, 4,596,000 shares and 900,281 shares, respectively	-198,378	-31,365
Total Shareholders’ Equity	2,321,212	2,394,414
Total Liabilities and Shareholders’ Equity	$5,325,997	$5,150,099

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Fixed maturities, available for sale, at fair value; amortized cost	$3,143,726	$3,026,256
Equity securities, trading, cost	274,324	203,308
Other investments, portion carried at fair value	30,058	0
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	62,283,426	62,096,787
Deferred tax expense (benefit) on accumulated other comprehensive income (loss)	$35,591	$32,127
Treasury shares, number of shares	4,596,000	900,281

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Changes in Capital (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Increase (Decrease) in Stockholders' Equity:	'	'	'	'
Beginning Balance	'	'	$2,394,414	$2,270,580
Common shares reacquired	'	'	-167,242	-7,964
Common shares issued for compensation	'	'	2,908	2,807
Share-based compensation	2,400	2,200	8,022	6,930
Net effect of restricted and performance shares issued and stock options exercised	'	'	-2,814	-3,968
Dividends to shareholders	'	'	-52,873	-46,375
Other comprehensive income (loss)	'	'	7,346	-75,307
Net income	34,778	63,357	131,451	226,658
Ending Balance	2,321,212	2,373,361	2,321,212	2,373,361
Common Stock	'	'	'	'
Increase (Decrease) in Stockholders' Equity:	'	'	'	'
Beginning Balance	'	'	621	619
Common shares reacquired	'	'	0	0
Common shares issued for compensation	'	'	0	0
Share-based compensation	'	'	0	0
Net effect of restricted and performance shares issued and stock options exercised	'	'	2	2
Dividends to shareholders	'	'	0	0
Other comprehensive income (loss)	'	'	0	0
Net income	'	'	0	0
Ending Balance	623	621	623	621
Additional Paid-in Capital	'	'	'	'
Increase (Decrease) in Stockholders' Equity:	'	'	'	'
Beginning Balance	'	'	349,894	341,780
Common shares reacquired	'	'	0	0
Common shares issued for compensation	'	'	2,679	2,807
Share-based compensation	'	'	8,022	6,930
Net effect of restricted and performance shares issued and stock options exercised	'	'	-2,816	-3,970
Dividends to shareholders	'	'	0	0
Other comprehensive income (loss)	'	'	0	0
Net income	'	'	0	0
Ending Balance	357,779	347,547	357,779	347,547
Accumulated Other Comprehensive Income (Loss)	'	'	'	'
Increase (Decrease) in Stockholders' Equity:	'	'	'	'
Beginning Balance	'	'	59,661	145,380
Common shares reacquired	'	'	0	0
Common shares issued for compensation	'	'	0	0
Share-based compensation	'	'	0	0
Net effect of restricted and performance shares issued and stock options exercised	'	'	0	0
Dividends to shareholders	'	'	0	0
Other comprehensive income (loss)	'	'	7,346	-75,307
Net income	'	'	0	0
Ending Balance	67,007	70,073	67,007	70,073
Retained Earnings	'	'	'	'
Increase (Decrease) in Stockholders' Equity:	'	'	'	'
Beginning Balance	'	'	2,015,603	1,782,857
Common shares reacquired	'	'	0	0
Common shares issued for compensation	'	'	0	0
Share-based compensation	'	'	0	0
Net effect of restricted and performance shares issued and stock options exercised	'	'	0	0
Dividends to shareholders	'	'	-52,873	-46,375
Other comprehensive income (loss)	'	'	0	0
Net income	'	'	131,451	226,658
Ending Balance	2,094,181	1,963,140	2,094,181	1,963,140
Treasury Stock	'	'	'	'
Increase (Decrease) in Stockholders' Equity:	'	'	'	'
Beginning Balance	'	'	-31,365	-56
Common shares reacquired	'	'	-167,242	-7,964
Common shares issued for compensation	'	'	229	0
Share-based compensation	'	'	0	0
Net effect of restricted and performance shares issued and stock options exercised	'	'	0	0
Dividends to shareholders	'	'	0	0
Other comprehensive income (loss)	'	'	0	0
Net income	'	'	0	0
Ending Balance	($198,378)	($8,020)	($198,378)	($8,020)

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Income and Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues	'	'	'	'
Net premiums earned	$177,028	$133,598	$525,061	$398,528
Net investment income	32,830	33,889	92,788	99,282
Equity in earnings (loss) of unconsolidated subsidiaries	298	-305	2,767	-3,500
Net realized investment gains (losses):	'	'	'	'
Other-than-temporary impairment (OTTI) losses	-1,425	0	-1,475	-71
Portion of OTTI losses recognized in (reclassified from) other comprehensive income before taxes	268	0	268	0
Net impairment losses recognized in earnings	-1,157	0	-1,207	-71
Other net realized investment gains (losses)	-6,974	12,500	8,866	47,721
Total net realized investment gains (losses)	-8,131	12,500	7,659	47,650
Other income	1,808	1,804	6,055	5,305
Total revenues	203,833	181,486	634,330	547,265
Expenses	'	'	'	'
Losses and loss adjustment expenses	106,486	65,619	306,591	203,885
Reinsurance recoveries	-7,264	-3,982	-18,948	-14,013
Net losses and loss adjustment expenses	99,222	61,637	287,643	189,872
Underwriting, policy acquisition and operating expenses	54,185	33,348	158,856	105,592
Segregated portfolio cells dividend expense	-483	0	2,355	0
Interest expense	3,606	322	10,697	1,085
Total expenses	156,530	95,307	459,551	296,549
Gain on acquisition	0	494	0	35,986
Income before income taxes	47,303	86,673	174,779	286,702
Provision for income taxes	'	'	'	'
Current expense (benefit)	15,591	12,687	37,884	36,902
Deferred expense (benefit)	-3,066	10,629	5,444	23,142
Total income tax expense (benefit)	12,525	23,316	43,328	60,044
Net income	34,778	63,357	131,451	226,658
Other comprehensive income (loss), after tax, net of reclassification adjustments	-14,646	-4,989	7,346	-75,307
Comprehensive income	$20,132	$58,368	$138,797	$151,351
Earnings per share:	'	'	'	'
Basic (USD per share)	$0.59	$1.02	$2.20	$3.67
Diluted (USD per share)	$0.59	$1.02	$2.19	$3.65
Weighted average number of common shares outstanding:	'	'	'	'
Basic (in shares)	58,676	61,844	59,807	61,793
Diluted (in shares)	58,931	62,108	60,047	62,040
Cash dividends declared per common share (USD per share)	$0.30	$0.25	$0.90	$0.75

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating Activities	'	'
Net income	$131,451	$226,658
Depreciation and amortization, net of accretion	36,286	34,364
Gain on acquisition	0	-35,986
Net realized investment gains	-7,659	-47,650
Share-based compensation	8,022	6,930
Deferred income taxes	5,444	23,142
Policy acquisition costs, net amortization (net deferral)	-5,249	-7,066
Other	-5,980	-8,367
Other changes in assets and liabilities, excluding effect of business combinations:	'	'
Premiums receivable	-42,406	-21,881
Reinsurance related assets and liabilities	-19,829	-1,510
Other assets	33,823	-34,016
Reserve for losses and loss adjustment expenses	-78,558	-104,387
Unearned premiums	55,565	23,574
Other liabilities	-9,827	-29,844
Net cash provided (used) by operating activities	101,083	23,961
Purchases of:	'	'
Fixed maturities, available for sale	-511,894	-406,152
Equity securities, trading	-85,986	-73,292
Other investments	-25,109	-7,926
Funding of tax credit limited partnerships	-8,439	-58,801
Investment in unconsolidated subsidiaries	-30,394	-15,637
Proceeds from sales or maturities of:	'	'
Fixed maturities, available for sale	486,702	782,612
Equity securities, trading	102,765	95,658
Other investments	15,074	2,352
Distributions from unconsolidated subsidiaries	3,850	14,564
Net sales or maturities (purchases) of short-term investments	177,013	-43,434
Cash received in acquisitions	35,013	22,780
Unsettled security transactions, net	-127	-2,744
(Increase) decrease in restricted cash	78,000	0
Other	3,467	-8,253
Net cash provided (used) by investing activities	239,935	301,727
Financing Activities	'	'
Repayment of long-term debt	0	-125,000
Repurchase of common stock	-163,146	-1,990
Dividends to shareholders	-53,820	-30,842
Other	-5,430	-7,356
Net cash provided (used) by financing activities	-222,396	-165,188
Increase (decrease) in cash and cash equivalents	118,622	160,500
Cash and cash equivalents at beginning of period	129,383	118,551
Cash and cash equivalents at end of period	248,005	279,051
Significant non-cash transactions	'	'
Deposit transferred as consideration for acquisition	$205,244	$153,700

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2014
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 U.S. generally accepted accounting principles (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- and nine-month periods ended September 30, 2014 are not necessarily indicative of the results that may be expected for the year ending December 31, 2014. The accompanying Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and Notes contained in ProAssurance’s December 31, 2013 report on Form 10-K. In connection with its preparation of the Condensed Consolidated Financial Statements, ProAssurance evaluated events that occurred subsequent to September 30, 2014 for recognition or disclosure in its financial statements and notes to financial statements.
	ProAssurance operates in four reportable segments as follows: Specialty Property and Casualty (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 13 of the Notes to Condensed Consolidated Financial Statements.
	Reclassifications
	On January 1, 2014, ProAssurance began reporting unearned ceding commissions as an offset to deferred policy acquisition costs (DPAC) on the Condensed Consolidated Balance Sheet, and the December 31, 2013 Condensed Consolidated Balance Sheet has been conformed to the current presentation. Previously, unearned ceding commissions ($0.8 million at December 31, 2013) were reported in Unearned premiums. Also, ceding commission income earned for the three and nine months ended September 30, 2014 and 2013 has been reported as an offset to DPAC amortization (see Note 6) which lowered DPAC amortization as previously reported for the three and nine months ended September 30, 2013 by $1.5 million and $4.2 million, respectively. Total underwriting, policy acquisition and operating expense for the 2013 three- and nine-month periods was not affected by the change in presentation.
	Intangible Assets
	Intangible assets with definite lives are amortized over the estimated useful life of the asset. Amortizable intangible assets primarily consist of agency and policyholder relationships, renewal rights and trade names and had a carrying value of $77.5 million at September 30, 2014 and $35.2 million at December 31, 2013. Intangible assets with an indefinite life, primarily state licenses, are not amortized and had carrying values of $25.8 million at September 30, 2014 and $16.8 million at December 31, 2013. Both amortizable and non-amortizable intangible assets increased during 2014 due to intangible assets purchased in the Eastern acquisition, see Note 2. Intangible assets are evaluated for impairment on an annual basis.
	Amortization expense for intangible assets for the three and nine months ended September 30, 2014 was $2.6 million and $7.7 million, respectively, and was $1.3 million and $4.0 million for the three and nine months ended September 30, 2013, respectively. Aggregate amortization expense for intangible assets over the next five years is estimated to be $2.6 million for the remainder of 2014, $8.3 million for 2015, $8.0 million for 2016, $5.7 million for 2017 and $5.3 million for 2018.
	Other Assets and Other Liabilities
	At December 31, 2013, Other assets was principally comprised of a deposit with an intermediate third-party of $205 million, related to the completion of the Eastern Insurance Holdings, Inc. (Eastern) acquisition which closed on January 1, 2014. See Note 2.
	At September 30, 2014, Other liabilities included $16.5 million in segregated portfolio cell (SPC) dividends payable related to our recently acquired Workers' Compensation segment. The SPC dividend payable represents the cumulative undistributed earnings of segregated portfolio cells that are contractually payable to external preferred shareholders of the cells.
	Accounting Policy Additions
	The significant accounting policies adopted as a result of the acquisition of Eastern and commencement of our Lloyd's Syndicate operations effective January 1, 2014 and followed by ProAssurance in making estimates that materially affect financial reporting are as follows:
	Earned But Unbilled Premiums (EBUB)
	Workers’ compensation premiums are determined based upon the payroll of the insured, the applicable premium rates and, where applicable, an experience based modification factor. An audit of the policyholders’ records is conducted after policy expiration to make a final determination of applicable premiums. Audit premium due from or due to a policyholder as a result of an audit is reflected in net premiums earned when billed. ProAssurance tracks, by policy, the amount of additional premium billed in final audit invoices as a percentage of payroll exposure and uses this information to estimate the probable additional amount that it has earned, but not yet billed, as of the balance sheet date. Changes to the EBUB estimate are included in Net premiums earned in the period recognized. As of September 30, 2014, ProAssurance carried earned but unbilled premiums of $3.4 million as a part of Premiums receivable.
	Convertible Bond Securities
	Investments in convertible bond 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. Interest on convertible bond securities is recorded on an accrual basis based on contractual interest rates and is included in Net investment income.
	Foreign Currency
	The functional currency of all ProAssurance foreign subsidiaries is the U.S. Dollar.
	Accounting Changes Not Yet Adopted
	Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity
	Effective for fiscal years beginning after December 15, 2014, the Financial Accounting Standards Board (FASB) issued guidance which changes the requirements for reporting discontinued operations. Under the new guidance, reporting entities are required to report disposals of business components only if the disposal represents a strategic shift in the entity’s operations that will have a major effect on the entity’s operations and financial results. The new guidance expands disclosure requirements for reported discontinued operations and requires disclosure of pre-tax profit or loss attributable to significant disposals that are not reported as discontinued operations. ProAssurance plans to adopt the guidance beginning January 1, 2015. Adoption of the guidance is expected to have no effect on ProAssurance’s results of operations or financial position.
	Equity Method and Joint Ventures-Accounting for Investments in Qualified Affordable Housing Projects
	Effective for fiscal years beginning after December 15, 2014, the FASB issued guidance which permits but does not require qualified reporting entities to use a new accounting method, the proportional amortization method, for investments in qualified affordable housing projects, also referred to as low income housing projects. Under the new method the initial cost of an investment is amortized in proportion to the tax benefits received, and investment performance is recognized as a component of income tax expense (benefit) rather than as a component of investment income. ProAssurance is in the process of evaluating whether it meets the qualification requirements for using the new method and the effect that the use of the new method would have on its results of operations and financial position. If ProAssurance elects to adopt the new method, the adoption will occur beginning January 1, 2015.
	Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period
	Effective for fiscal years beginning after December 15, 2015, the FASB issued guidance for share-based payments in which the terms of the award provide that a performance target can be achieved after completion of the requisite service period. The new guidance provides that compensation cost for such awards should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. ProAssurance plans to adopt the guidance beginning January 1, 2016. Adoption of the guidance is expected to have no effect on ProAssurance’s results of operations or financial position as ProAssurance has no awards with performance targets extending beyond the requisite service period.
	Revenue from Contracts with Customers
	Effective for fiscal years beginning after December 15, 2016, the FASB issued guidance related to revenue from contracts with customers. The core principle of the new guidance is that revenue should be 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, 2017. 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 expected to have no material effect on ProAssurance’s results of operations or financial position.
	Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern
	Effective for fiscal years ending after December 15, 2016 and interim periods beginning after December 15, 2016, the FASB issued guidance that establishes principles and definitions related to management's evaluation of whether there is substantial doubt about the organization's ability to continue as a going concern. For each interim and annual reporting period, the new guidance requires management to evaluate the organization's ability to meet its obligations as they are due within one year of the date the financial statements are issued and requires disclosure when there is substantial doubt regarding the organization's ability to continue as a going concern. ProAssurance plans to adopt the guidance beginning December 15, 2016. Adoption is expected to have no effect on ProAssurance’s results of operations or financial position.
	Accounting Changes Adopted
	Obligations Resulting from Joint and Several Liability Arrangements
	Effective for fiscal years beginning after December 15, 2013, the FASB revised guidance related to obligations resulting from joint and several liability arrangements. The new guidance requires an entity to recognize, measure and disclose obligations resulting from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date, except for obligations already addressed within existing GAAP guidance, with retrospective application required for such arrangements existing at the beginning of the fiscal year of adoption. ProAssurance adopted the guidance on January 1, 2014. Adoption of this guidance had no effect on ProAssurance's results of operations or financial position.
	Presentation of Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists
	Effective for fiscal years beginning after December 15, 2013, the FASB issued guidance related to the financial statement presentation of unrecognized tax benefits. The new guidance requires an entity to present unrecognized tax benefits as a reduction to a deferred tax asset resulting from a net operating loss carryforward, a similar tax loss, or tax credit carryforward except in circumstances where the relevant taxing authority does not permit offset or does not require offset and the entity does not intend to use the deferred tax asset for offset. The guidance requires prospective application for all unrecognized tax benefits that exist as of the effective date, but may be applied retrospectively. ProAssurance adopted the guidance prospectively on January 1, 2014. Adoption of this guidance had no material effect on ProAssurance's results of operations or financial position.

Business_Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Business Combinations	'
	Business Combinations
	All entities acquired in 2014 were accounted for in accordance with GAAP relating to business combinations.
	On January 1, 2014, ProAssurance completed the acquisition of Eastern by purchasing 100% of its outstanding common shares for cash of $205 million. Eastern is based in Lancaster, Pennsylvania and specializes in workers' compensation insurance and reinsurance products and services, including alternative market solutions. ProAssurance incurred expenses related to the purchase of approximately $2.1 million during the first nine months of 2014 and approximately $0.9 million during the year ended December 31, 2013. These expenses were included as a part of operating expenses in the periods incurred.
	The purchase consideration for Eastern was allocated to the assets acquired and liabilities assumed based on their estimated fair values on the acquisition date. Goodwill of $49.6 million was recognized equal to the excess of the purchase price over the net fair value of identifiable assets acquired and liabilities assumed. Factors contributing to the recognition of goodwill include strategic and synergistic benefits that are expected to be realized as a result of the acquisition. These benefits include insurance market diversification, expanded access to alternative markets, and opportunities to reach additional insureds in the healthcare market by being a single source provider of a suite of insurance products. None of the goodwill is expected to be tax deductible. The allocation of purchase consideration is shown in the table below.
	(In thousands)
	Fixed maturities, available for sale		$	107,131
	Equity securities, trading		65,945
	Cash and short-term investments		58,944
	Other investments		42,133
	Premiums receivable		71,989
	Receivable from reinsurers on paid and unpaid losses and LAE		18,942
	Intangible assets		59,000
	Deferred policy acquisition costs (see discussion below)		10,593
	Other assets		19,225
	Reserve for losses and loss adjustment expenses		(153,191		)
	Unearned premiums		(80,268		)
	Ceded balances payable		(9,507		)
	Segregated portfolio cells dividends payable		(14,430		)
	Deferred tax liabilities, net		(12,835		)
	Other liabilities		(28,038		)
	Fair value of net assets acquired		$	155,633
	Goodwill		49,610
	Total purchase consideration		$	205,243
	Intangible assets acquired included the following:
	(In millions)	Estimated Fair Value on Acquisition Date		Estimated Useful Life
	Agency relationships	$27.00		15
	Policyholder relationships	8		15
	Trade names	8		15
	Non-compete agreements	7		3
	Total intangibles subject to amortization	$50.00		13	*
	Insurance license agreements	$9.00		Indefinite
	* Reflects the weighted average estimated useful life of acquired intangible assets that are subject to amortization.
	ProAssurance's fair value estimate of the value of business acquired (VOBA), calculated as the present value of future earnings expected from the insurance contracts acquired, approximated the carrying value of Eastern's asset for deferred policy acquisition costs as of the acquisition date. Consequently, Eastern's asset for deferred policy acquisition costs was recognized in the purchase price allocation, as listed above, in lieu of recognizing an intangible asset for VOBA.
	ProAssurance believes that all contractual cash flows related to acquired receivables will be collected. The fair value of the reserve for losses and loss adjustment expenses and related reinsurance recoverables was based on three components: an actuarial estimate of the expected future net cash flows, a reduction to those cash flows for the time value of money determined utilizing the U.S. Treasury Yield Curve, and a risk margin adjustment to reflect the net present value of profit that an investor would demand in return for the assumption of the development risk associated with the reserve. The fair value of the reserve, including the risk margin adjustment, exceeded the undiscounted loss reserve previously established by Eastern by $9.3 million; this fair value adjustment is being amortized over the average expected life of the reserve of 6 years as a reduction to loss expenses.
	The following table provides Pro Forma Consolidated Results for the three and nine months ended September 30, 2014 and 2013 as if the Eastern transaction had occurred on January 1, 2013. ProAssurance Actual Consolidated Results have been adjusted by the following, net of related tax effects, to reflect the Pro Forma Consolidated Results below.
	•	For the three and nine months ended September 30, 2013, ProAssurance 2013 Actual Consolidated Results, which did not include Eastern, have been adjusted to include Eastern's 2013 operating results. ProAssurance Actual Consolidated Results for the three and nine months ended September 30, 2014 included Eastern's operating results (Revenue of $49.6 million and $149.9 million, respectively, and Net income of $1.7 million and $7.1 million, respectively).
	•	Certain costs included in ProAssurance actual results for the three and nine months ended September 30, 2014 have been reported in the Pro Forma Consolidated Results as if the costs had been incurred for the three and nine months ended September 30, 2013. Such costs include direct transaction costs and certain compensation costs directly related to the integration of Eastern operations.
	•	Actual Consolidated Results for the three and nine months ended September 30, 2013, were reduced to reflect amortization of intangible assets and debt security premiums and discounts recorded as a part of the Eastern purchase price allocation.
		Three Months Ended September 30, 2014				Nine Months Ended September 30, 2014
	(In thousands)	ProAssurance		ProAssurance		ProAssurance	ProAssurance
		Pro Forma		Actual		Pro Forma	Actual
		Consolidated		Consolidated Results		Consolidated	Consolidated Results
		Results				Results
	Revenue	$203,833		$203,833		$634,330	$634,330
	Net income	$34,759		$34,778		$132,451	$131,451
		Three Months Ended September 30, 2013				Nine Months Ended September 30, 2013
	(In thousands)	ProAssurance		ProAssurance		ProAssurance	ProAssurance
		Pro Forma		Actual		Pro Forma	Actual
		Consolidated		Consolidated Results		Consolidated	Consolidated Results
		Results				Results
	Revenue	$229,608		$181,486		$686,391	$547,265
	Net income	$66,868		$63,357		$233,666	$226,658

Fair_Value_Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2014
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 September 30, 2014 and December 31, 2013, including financial instruments for which ProAssurance has elected fair value, are shown in the following tables. 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.
		30-Sep-14
		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	$	—			$	176,813			$	—		$	176,813
	U.S. Government-sponsored enterprise obligations	—				43,966				—			43,966
	State and municipal bonds	—				1,082,040				5,594			1,087,634
	Corporate debt, multiple observable inputs	—				1,459,550				—			1,459,550
	Corporate debt, limited observable inputs:
	Other corporate debt, NRSRO ratings available	—				—				10,793			10,793
	Other corporate debt, NRSRO ratings not available	—				—				2,642			2,642
	Residential mortgage-backed securities	—				290,314				—			290,314
	Agency commercial mortgage-backed securities	—				16,893				—			16,893
	Other commercial mortgage-backed securities	—				57,323				—			57,323
	Other asset-backed securities	—				96,119				4,773			100,892
	Equity securities
	Financial	75,141				—				—			75,141
	Utilities/Energy	26,551				—				—			26,551
	Consumer oriented	64,912				—				—			64,912
	Industrial	54,912				—				—			54,912
	Bond funds	53,178				—				—			53,178
	All other	31,937				—				—			31,937
	Short-term investments	94,323				650				—			94,973
	Financial instruments carried at fair value, classified as a part of:
	Investment in unconsolidated subsidiaries	—				—				110,793			110,793
	Other investments	4,830				25,228				—			30,058
	Total assets	$	405,784			$	3,248,896			$	134,595		$	3,789,275
		31-Dec-13
		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	$	—			$	170,714			$	—		$	170,714
	U.S. Government-sponsored enterprise obligations	—				32,768				—			32,768
	State and municipal bonds	—				1,147,328				7,338			1,154,666
	Corporate debt, multiple observable inputs	—				1,346,977				—			1,346,977
	Corporate debt, limited observable inputs:
	Other corporate debt, NRSRO ratings available	—				—				11,449			11,449
	Other corporate debt, NRSRO ratings not available	—				—				2,727			2,727
	Residential mortgage-backed securities	—				235,614				—			235,614
	Agency commercial mortgage-backed securities	—				27,475				—			27,475
	Other commercial mortgage-backed securities	—				61,390				—			61,390
	Other asset-backed securities	—				67,455				6,814			74,269
	Equity securities
	Financial	81,536				—				—			81,536
	Utilities/Energy	32,350				—				—			32,350
	Consumer oriented	66,461				—				—			66,461
	Industrial	57,262				—				—			57,262
	All other	15,932				—				—			15,932
	Short-term investments	248,605											248,605
	Financial instruments carried at fair value, classified as a part of:
	Investment in unconsolidated subsidiaries	—				—				72,062			72,062
	Total assets	$	502,146			$	3,089,721			$	100,390		$	3,692,257
	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. If a value did not appear reasonable, the valuation was discussed with the service that provided the value and would have been adjusted, if necessary. No such adjustments were necessary in 2014 or 2013.
	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 recent significant economic or geographic events or ratings changes affecting the security’s fair value.
Corporate debt with 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 by an outside vendor based upon a widely distributed, loan-specific listing of average bid and ask prices published daily by an investment industry group. The publisher of the listing derived the averages from data received from multiple market-makers for bank loans.
Residential and commercial mortgage backed securities. Agency pass-through securities were valued using a matrix, considering the issuer type, coupon rate and longest cash flows outstanding. The matrix was developed daily based on 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. Valuations of Alt-A mortgages included a review of collateral performance data, which is generally updated monthly.
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 considered collateral type. Valuations of subprime home equity loans used the same valuation methodology as previously described for Alt-A mortgages.
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 bond securities. Convertible bonds were valued using a pricing model that incorporated selected dealer quotes as well as real-time market data including 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 price.
•	Exclusive of Investments in unconsolidated subsidiaries, which are valued at net asset value (NAV), the securities noted in the disclosure 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
State and municipal bonds consisted of auction rate municipal bonds valued internally using either published quotes for similar securities or values produced by discounted cash flow models using yields currently available on fixed rate securities with a similar term and collateral, adjusted to consider the effect of a floating rate and a premium for illiquidity. At September 30, 2014, 100% of the securities were rated; the average rating was A.
Corporate debt with 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 having like terms and payment features that are of comparable credit quality. Assessments of credit quality were based on NRSRO ratings, if available, or were subjectively determined by management if not available. At September 30, 2014, the average rating of rated securities was A-.
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.
Investment in unconsolidated subsidiaries consisted of limited partnership (LP) and limited liability company (LLC) interests valued using the NAV provided by the LP/LLC, which approximated the fair value of the interest.
Such interests include the following:
	Unfunded		Fair Value
	Commitments
(In thousands)	September 30,		September 30,				December 31,
	2014		2014				2013
Investments in LPs/LLCs:
Secured debt fund (1)	$16,200		$	23,896			$	13,233
Long equity fund (2)	None		7,034				6,574
Long/Short equity funds (3)	None		25,016				28,385
Non-public equity funds (4)	$71,518		42,818				23,870
Multi-strategy fund of funds (5)	None		8,263				—
Structured credit fund (6)	None		3,766				—
			$	110,793			$	72,062
-1	The LP is structured to provide income and capital appreciation primarily through investments in senior secured debt. Redemptions are not allowed. Income and capital are to be periodically distributed at the discretion of the LP over an anticipated time frame that spans from 7 to 9 years.
-2	The LP 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	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 event-driven market opportunities. The funds generally permit quarterly or semi-annual redemptions of the investors’ existing capital balance with 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	Comprised of interests in three 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 LPs. One LP allows redemption by special consent; 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 from 4 to 12 years.
-5	The LLC is 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 the LLC Board is permitted discretion to periodically extend offers to repurchase units of the LLC.
-6	The LP seeks 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.
ProAssurance may not sell, transfer or assign its interest in any of the above LPs/LLCs without special consent from the LPs/LLCs.
Quantitative Information Regarding Level 3 Valuations
Quantitative Information about Level 3 Fair Value Measurements
		Fair Value at
(In millions)		30-Sep-14		31-Dec-13		Valuation Technique		Unobservable Input		Range
										(Weighted Average)
Assets:
State and municipal bonds		$5.60		$7.30		Market Comparable		Comparability Adjustment		0% - 10% (5%)
						Securities
						Discounted Cash Flows		Comparability Adjustment		0% - 10% (5%)
Corporate debt with limited observable inputs		$13.40		$14.20		Market Comparable		Comparability Adjustment		0% - 5% (2.5%)
						Securities
						Discounted Cash Flows		Comparability Adjustment		0% - 5% (2.5%)
Other asset-backed securities		$4.80		$6.80		Market Comparable		Comparability Adjustment		0% - 5% (2.5%)
						Securities
						Discounted Cash Flows		Comparability Adjustment		0% - 5% (2.5%)
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.
	30-Sep-14
	Level 3 Fair Value Measurements – Assets
(In thousands)	U.S. Government-sponsored Enterprise Obligations				State and Municipal Bonds				Corporate Debt			Asset-backed Securities			Investment in Unconsolidated Subsidiaries			Total
Balance June 30, 2014	$	—			$	7,148			$	14,544		$	5,960		$	101,342		$	128,994
Total gains (losses) realized and unrealized:
Included in earnings, as a part of:
Net investment income	—				(4		)		16			—			—			12
Equity in earnings of unconsolidated subsidiaries	—				—				—			—			(683		)	(683		)
Net realized investment gains (losses)	—				—				—			—			—			—
Included in other comprehensive income	—				(76		)		35			(6		)	—			(47		)
Purchases	—				—				(499		)	—			12,055			11,556
Sales	—				(1,474		)		(661		)	—			(1,921		)	(4,056		)
Transfers in	—				—				—			—			—			—
Transfers out	—				—				—			(1,181		)	—			(1,181		)
Balance September 30, 2014	$	—			$	5,594			$	13,435		$	4,773		$	110,793		$	134,595
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	$	—			$	—			$	—		$	—		$	(683	)	$	(683	)
	30-Sep-14
	Level 3 Fair Value Measurements – Assets
(In thousands)	U.S. Government-sponsored Enterprise Obligations				State and Municipal Bonds				Corporate Debt			Asset-backed Securities			Investment in Unconsolidated Subsidiaries			Total
Balance December 31, 2013	$	—			$	7,338			$	14,176		$	6,814		$	72,062		$	100,390
Total gains (losses) realized and unrealized:
Included in earnings, as a part of:
Net investment income	—				(10		)		48			—			—			38
Equity in earnings of unconsolidated subsidiaries	—				—				—			—			5,413			5,413
Net realized investment gains (losses)	—				(95		)		3			—			—			(92		)
Included in other comprehensive income	1				(34		)		702			63			—			732
Purchases	1,000				1,861				2,000			3,340			37,430			45,631
Sales	—				(1,731		)		(1,469		)	(61		)	(4,112		)	(7,373		)
Transfers in	—				2,119				—			305			—			2,424
Transfers out	(1,001		)		(3,854		)		(2,025		)	(5,688		)	—			(12,568		)
Balance September 30, 2014	$	—			$	5,594			$	13,435		$	4,773		$	110,793		$	134,595
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	$	—			$	—			$	—		$	—		$	5,413		$	5,413
	30-Sep-13
	Level 3 Fair Value Measurements – Assets
(In thousands)	U.S. Government-sponsored Enterprise Obligations				State and Municipal Bonds				Corporate Debt			Asset-backed Securities			Investment in Unconsolidated Subsidiaries			Total
Balance June 30, 2013	$	—			$	5,025			$	11,359		$	4,679		$	44,549		$	65,612
Total gains (losses) realized and unrealized:
Included in earnings, as a part of:
Net investment income	—				—				(1		)	—			—			(1		)
Equity in earnings of unconsolidated subsidiaries	—				—				—			—			1,301			1,301
Net realized investment gains (losses)	—				—				—			—			—			—
Included in other comprehensive income	—				—				(221		)	16			—			(205		)
Purchases	—				—				—			—			2,354			2,354
Sales	—				—				(503		)	—			(3,548		)	(4,051		)
Transfers in	—				—				100			—			—			100
Transfers out	—				—				—			—			—			—
Balance September 30, 2013	$	—			$	5,025			$	10,734		$	4,695		$	44,656		$	65,110
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	$	—			$	—			$	—		$	—		$	1,301		$	1,301
	30-Sep-13
	Level 3 Fair Value Measurements – Assets
(In thousands)	U.S. Government-sponsored Enterprise Obligations				State and Municipal Bonds				Corporate Debt			Asset-backed Securities			Investment in Unconsolidated Subsidiaries			Total
Balance December 31, 2012	$	—			$	7,175			$	15,191		$	4,035		$	33,739		$	60,140
Total gains (losses) realized and unrealized:
Included in earnings, as a part of:
Net investment income	—				—				(103		)	(17		)	—			(120		)
Equity in earnings of unconsolidated subsidiaries	—				—				—			—			3,582			3,582
Net realized investment gains (losses)	—				(44		)		(69		)	—			—			(113		)
Included in other comprehensive income	—				—				(514		)	(81		)	—			(595		)
Purchases	—				—				7,470			1,356			20,975			29,801
Sales	—				(2,106		)		(1,368		)	(18		)	(13,640		)	(17,132		)
Transfers in	—				—				100			1,701			—			1,801
Transfers out	—				—				(9,973		)	(2,281		)	—			(12,254		)
Balance September 30, 2013	$	—			$	5,025			$	10,734		$	4,695		$	44,656		$	65,110
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	$	—			$	—			$	—		$	—		$	3,582		$	3,582
Transfers
There were no transfers between the Level 1 and Level 2 categories during the three and nine months ended September 30, 2014 or 2013.
Transfers shown in the preceding Level 3 Tables were as of the end of the period and were to or from Level 2, unless otherwise noted.
All transfers during the three and nine months ended September 30, 2014 and September 30, 2013 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.
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.
	30-Sep-14								31-Dec-13
(In thousands)	Carrying				Fair				Carrying			Fair
	Value				Value				Value			Value
Financial assets:
BOLI	$	55,918			$	55,918			$	54,374		$	54,374
Other investments	61,952				63,247				52,240			51,833
Other assets	21,298				21,248				17,940			17,940
Financial liabilities:
Senior notes due 2023	$	250,000			$	273,750			$	250,000		$	262,500
Other liabilities	14,022				14,139				13,303			13,303
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 LPs/LLCs accounted for using the cost method, investments in Federal Home Loan Bank (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 NAVs provided by the LP/LLC managers. 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 NAVs of the underlying securities. Other assets also included a secured note receivable and an unsecured receivable under a revolving credit agreement. 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. Other liabilities also included certain contractual liabilities related to prior business combinations. The fair values of the business combination liabilities were based on the present value of the expected future cash outflows, discounted at ProAssurance’s assumed incremental borrowing rate on the valuation date for unsecured liabilities with similar repayment structures.
The fair value of the long-term 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	9 Months Ended
	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]	'
Investments	'
	Investments
	Available-for-sale securities at September 30, 2014 and December 31, 2013 included the following:
		30-Sep-14
	(In thousands)	Amortized				Gross Unrealized Gains			Gross Unrealized Losses			Estimated Fair Value
		Cost
	Fixed maturities
	U.S. Treasury obligations	$	173,632			$	4,396		$	1,215		$	176,813
	U.S. Government-sponsored enterprise obligations	42,480				1,709			223			43,966
	State and municipal bonds	1,038,278				50,055			699			1,087,634
	Corporate debt	1,433,266				48,894			9,175			1,472,985
	Residential mortgage-backed securities	282,717				8,817			1,220			290,314
	Agency commercial mortgage-backed securities	16,785				172			64			16,893
	Other commercial mortgage-backed securities	55,853				1,587			117			57,323
	Other asset-backed securities	100,715				346			169			100,892
		$	3,143,726			$	115,976		$	12,882		$	3,246,820
		31-Dec-13
	(In thousands)	Amortized				Gross Unrealized Gains			Gross Unrealized Losses			Estimated Fair Value
		Cost
	Fixed maturities
	U.S. Treasury obligations	$	166,115			$	6,118		$	1,519		$	170,714
	U.S. Government-sponsored enterprise obligations	30,942				2,251			425			32,768
	State and municipal bonds	1,116,060				46,533			7,927			1,154,666
	Corporate debt	1,321,838				53,059			13,744			1,361,153
	Residential mortgage-backed securities	230,861				7,608			2,855			235,614
	Agency commercial mortgage-backed securities	27,268				343			136			27,475
	Other commercial mortgage-backed securities	59,066				2,491			167			61,390
	Other asset-backed securities	74,106				487			324			74,269
		$	3,026,256			$	118,890		$	27,097		$	3,118,049
	The recorded cost basis and estimated fair value of available-for-sale fixed maturities at September 30, 2014, 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
		Cost				year or less			one year			five years			ten years		Value
									through			through
									five years			ten years
	Fixed maturities, available for sale
	U.S. Treasury obligations	$	173,632			$	19,612		$	104,211		$	48,950		$	4,040	$	176,813
	U.S. Government-sponsored enterprise obligations	42,480				8,002			25,465			10,160			339		43,966
	State and municipal bonds	1,038,278				49,169			393,569			442,212			202,684		1,087,634
	Corporate debt	1,433,266				157,683			694,254			598,183			22,865		1,472,985
	Residential mortgage-backed securities	282,717															290,314
	Agency commercial mortgage-backed securities	16,785															16,893
	Other commercial mortgage-backed securities	55,853															57,323
	Other asset-backed securities	100,715															100,892
		$	3,143,726														$	3,246,820
	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 September 30, 2014.
	Cash and securities with a carrying value of $48.2 million at September 30, 2014 were on deposit with various state insurance departments to meet regulatory requirements.
	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 Funds at Lloyd's (FAL). ProAssurance investments at September 30, 2014 included fixed maturities with a fair value of $71.5 million and short term investments with a fair value of approximately $5.7 million on deposit with Lloyd's in order to satisfy these FAL requirements.
	Business Owned Life Insurance (BOLI)
	ProAssurance holds BOLI policies on management employees that are carried at the current cash surrender value of the policies (original cost $33 million). 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 principal beneficiary of these policies.
	Other Investments
	Other investments at September 30, 2014 and December 31, 2013 was comprised as follows:
	(In thousands)	September 30,				December 31,
		2014				2013
	Investments in LPs/LLCs, at cost	$	57,607			$	47,258
	Convertible securities, at fair value, see Note 1	30,058				—
	Other, principally FHLB capital stock, at cost	4,345				4,982
		$	92,010			$	52,240
	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.
	Unconsolidated Subsidiaries
	ProAssurance holds investments in unconsolidated subsidiaries, accounted for under the equity method. The investments include the following:
		30-Sep-14					Carrying Value
	(In thousands)	Unfunded		Percentage			September 30,			December 31,
		Commitments*		Ownership			2014			2013
	Investment in LPs/LLCs:
Tax credit partnerships	$15,710		See below			$	137,386		$	142,174
Secured debt fund	$16,200		<	20%		23,896			13,233
Long equity fund	None		<	20%		7,034			6,574
Long/short equity funds	None		<	25%		25,016			28,385
Non-public equity funds	$88,034		<	20%		46,127			23,870
Multi-strategy fund of funds	None		<	20%		8,263			—
Structured credit fund	None		<	20%		3,766			—
Real estate fund	$6,526		<	20%		3,474			—
						$	254,962		$	214,236
* Unfunded commitments are included in the carrying value of tax credit partnerships only.
Tax credit partnership interests held by ProAssurance generate investment returns by providing tax benefits to fund investors in the form of project operating losses and tax credits. The related properties are principally low income housing projects. ProAssurance's ownership percentage relative to two of the tax credit partnership interests is almost 100%; these interests had a carrying value of $60.9 million at September 30, 2014. ProAssurance's ownership percentage relative to the remaining tax credit partnership interests is less than 20%; these interests had a carrying value of $76.5 million at September 30, 2014. All are accounted for under the equity method as ProAssurance does not have the ability to exert control over the partnerships.
The Secured debt fund is structured to provide interest distributions and capital appreciation primarily through investments in senior secured debt.
The Long equity fund targets long-term total returns through holdings in public international companies.
The Long/Short equity fund targets absolute returns using a strategy designed to take advantage of event-driven market opportunities.
The Non-public equity funds hold diversified private equities and are structured to provide capital appreciation.
The Multi-strategy fund of funds holds portfolios having little or no correlation to the broader fixed income and equity security markets.
The Structured credit fund seeks to obtain superior risk-adjusted absolute returns by acquiring and actively managing a diversified portfolio of debt securities.
The Real estate fund invests in multi-tenant industrial real estate with the objective of achieving superior absolute returns in all market cycles.
Investments Held in a Loss Position
The following tables provide summarized information with respect to investments held in an unrealized loss position at September 30, 2014 and December 31, 2013, including the length of time the investment had been held in a continuous unrealized loss position.
	30-Sep-14
	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	$	59,770			$	1,215		$	37,309		$	534		$	22,461	$	681
U.S. Government-sponsored enterprise obligations	7,887				223			2,136			22			5,751		201
State and municipal bonds	71,155				699			32,129			128			39,026		571
Corporate debt	477,806				9,175			372,670			5,909			105,136		3,266
Residential mortgage-backed securities	66,143				1,220			26,012			105			40,131		1,115
Agency commercial mortgage-backed securities	10,432				64			8,536			8			1,896		56
Other commercial mortgage-backed securities	14,592				117			7,528			33			7,064		84
Other asset-backed securities	39,328				169			35,269			77			4,059		92
	$	747,113			$	12,882		$	521,589		$	6,816		$	225,524	$	6,066
Other investments
Investments in LPs/LLCs carried at cost	$	17,106			$	582		$	15,458		$	577		$	1,648	$	5
	31-Dec-13
	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	$	47,668			$	1,519		$	44,304		$	1,182		$	3,364	$	337
U.S. Government-sponsored enterprise obligations	6,640				425			5,752			321			888		104
State and municipal bonds	203,970				7,927			184,401			6,640			19,569		1,287
Corporate debt	349,277				13,744			324,510			12,061			24,767		1,683
Residential mortgage-backed securities	93,608				2,855			84,045			2,393			9,563		462
Agency commercial mortgage-backed securities	11,658				136			11,082			116			576		20
Other commercial mortgage-backed securities	11,153				167			10,215			159			938		8
Other asset-backed securities	25,539				324			21,804			77			3,735		247
	$	749,513			$	27,097		$	686,113		$	22,949		$	63,400	$	4,148
Other investments
Investments in LPs/LLCs carried at cost	$	14,752			$	1,059		$	13,166		$	1,018		$	1,586	$	41
As of September 30, 2014, excluding U.S. government backed securities, there were 617 debt securities (21.1% of all available-for-sale fixed maturity securities held) in an unrealized loss position representing 441 issuers. The greatest and second greatest unrealized loss position among those securities was approximately $0.5 million and $0.3 million, respectively. The securities were evaluated for impairment as of September 30, 2014.
As of December 31, 2013, excluding U.S. government backed securities, there were 714 debt securities (26.3% of all available-for-sale fixed maturity securities held) in an unrealized loss position representing 516 issuers. Both the greatest and second greatest unrealized loss position among those securities approximated $0.4 million. The securities were evaluated for impairment as of December 31, 2013.
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 other-than-temporary impairment 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, 2013 Form 10-K.
Fixed maturity securities held in an unrealized loss position at September 30, 2014, 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 September 30, 2014 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							Nine Months Ended
	30-Sep							30-Sep
(In thousands)	2014				2013			2014			2013
Fixed maturities	$	28,442			$	30,672		$	85,402		$	93,687
Equities	2,661				2,394			7,479			7,000
Short-term investments and Other invested assets	2,793				2,000			4,723			2,514
Business owned life insurance	646				633			1,544			1,508
Investment fees and expenses	(1,712		)		(1,810		)	(6,360		)	(5,427		)
Net investment income	$	32,830			$	33,889		$	92,788		$	99,282
Net Realized Investment Gains (Losses)
Realized investment gains and losses are recognized on the specific identification basis. The following table provides detailed information regarding net realized investment gains (losses):
	Three Months Ended September 30							Nine Months Ended September 30
(In thousands)	2014				2013			2014			2013
Total other-than-temporary impairment losses:
State and municipal bonds	$	—			$	—		$	(50	)	$	(71	)
Corporate debt	(1,425		)		—			(1,425		)	—
Portion recognized in (reclassified from) Other Comprehensive Income:
Corporate debt	268				—			268			—
Net impairments recognized in earnings	$	(1,157	)		$	—		$	(1,207	)	$	(71	)
Gross realized gains, available-for-sale securities	736				7,708			3,711			14,631
Gross realized (losses), available-for-sale securities	(52		)		(5,305		)	(371		)	(6,269		)
Net realized gains (losses), trading securities	3,227				5,818			21,830			14,650
Net realized gains (losses), Other investments	55				—			321			—
Change in unrealized holding gains (losses), trading securities	(10,402		)		3,355			(17,906		)	23,784
Change in unrealized holding gains (losses), convertible securities, carried at fair value	(538		)		—			1,281			—
Other	—				924			—			925
Net realized investment gains (losses)	$	(8,131	)		$	12,500		$	7,659		$	47,650
Credit-related impairments related to two corporate debt instruments were recognized in the third quarter of 2014. Additionally, a non-credit impairment related to one of the instruments was recognized as the fair value of the instrument was less than the expected future cash flows from the security. No significant impairment losses were recognized in the 2013 three- and nine-month periods.
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 other-than-temporary impairment was recorded in Other comprehensive income.
	Three Months Ended September 30							Nine Months Ended September 30
(In thousands)	2014				2013			2014			2013
Balance beginning of period	$	83			$	413		$	83		$	3,301
Additional credit losses recognized during the period, related to securities for which:
No OTTI has been previously recognized	149				—			149			—
Reductions due to:
Securities sold during the period (realized)	—				(330		)	—			(3,218		)
Balance September 30	$	232			$	83		$	232		$	83
Other information regarding sales and purchases of available-for-sale securities is as follows:
	Three Months Ended September 30							Nine Months Ended September 30
(In millions)	2014				2013			2014			2013
Proceeds from sales (exclusive of maturities and paydowns)	$	24.8			$	319.2		$	147.3		$	494.8
Purchases	$	146.5			$	98.8		$	511.9		$	406.2

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
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, because ProAssurance utilizes tax credit benefits transferred from tax credit partnership investments, and in 2013, because ProAssurance recognized a non-taxable gain related to an acquisition.
	In 2013 the IRS issued a Notice of Proposed Adjustment (NOPA) for the 2009 and 2010 tax years. ProAssurance subsequently protested certain issues in the NOPA, all of which related to the timing of deductions. In April 2014, ProAssurance and the IRS reached a final settlement on all contested issues which resulted in no additional tax liability for ProAssurance. ProAssurance subsequently received IRS refunds totaling $30.6 million, exclusive of interest, which included a refund from the settlement of non-contested issues addressed by the NOPA, and return of a protective payment made in 2013.
	The statute of limitations is now closed for all tax years prior to 2011.
	The liability for unrecognized tax benefits was $0.6 million at September 30, 2014 and $4.8 million at December 31, 2013. All unrecognized benefits included in the December 31, 2013 balance were attributable to timing issues which fully reversed during the first quarter of 2014; an additional $0.6 million was added to the liability in 2014 as a result of the acquisition of Eastern.
	ProAssurance had receivables for federal income taxes of $11.4 million at September 30, 2014 and $27.3 million at December 31, 2013, both carried as a part of Other Assets.

Deferred_Policy_Acquisition_Co

Deferred Policy Acquisition Costs	9 Months Ended
	Sep. 30, 2014
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 deferred policy acquisition costs was $16.7 million and $52.9 million for the three and nine months ended September 30, 2014, respectively, and $13.9 million and $39.0 million for the three and nine months ended September 30, 2013, respectively.

Reserve_for_Losses_and_Loss_Ad

Reserve for Losses and Loss Adjustment Expenses	9 Months Ended
	Sep. 30, 2014
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 significantly 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.
	During the three and nine months ended September 30, 2014, ProAssurance recognized favorable net loss development of $42.9 million and $133.3 million, respectively, related to prior accident years, of which $0.6 million and $2.9 million, respectively, related to the loss reserve assumed in the acquisition of Eastern. The favorable net loss development reflected reductions in the Company's estimates of claims severity, principally related to the 2007 through 2012 accident years.
	For the three and nine months ended September 30, 2013, ProAssurance recognized favorable net loss development of $49.4 million and $141.0 million, respectively, to reflect reductions in estimated claims severity. The favorable net loss development reflected reductions in the Company's estimates of claims severity, principally related to the 2005 through 2011 accident years.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
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 2013 Form 10-K.
	ProAssurance has funding commitments primarily related to non-public investment entities totaling approximately $164.7 million, expected to be paid as follows: $22.6 million in 2014, $124.7 million in 2015 and 2016 combined, $16.5 million in 2017 and 2018 combined, and $0.9 million thereafter.
	As a member of Lloyd's and a capital provider to Syndicate 1729, ProAssurance is required to provide capital, referred to as FAL. At September 30, 2014, ProAssurance is satisfying the FAL requirement with investment securities on deposit with Lloyd's with a carrying value of $77.2 million (see Note 4). ProAssurance anticipates its FAL requirement for the 2015 underwriting year to be approximately £50.9 million, which would require ProAssurance to fund an additional £5.8 million (approximately $9.8 million if funded with U.S. currency) during 2014. At December 31, 2013, the FAL requirement was primarily met through a standby letter of credit (LOC).
	ProAssurance has also issued an unconditional revolving credit agreement (the Credit Agreement) of up to £10 million ($16 million at September 30, 2014) to the Premium Trust Fund of Syndicate 1729 for the purpose of providing working capital. Advances under the Credit Agreement bear interest at 8.5% annually, and are repayable upon demand after December 31, 2016. As of September 30, 2014, £5.5 million ($9.2 million) had been advanced under the Credit Agreement.

Longterm_Debt

Long-term Debt	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Long-term Debt	'
	Long-term Debt
	ProAssurance’s outstanding long-term debt consisted of the following:
	(In thousands)	September 30,		December 31,
		2014		2013
	Senior notes due 2023, unsecured, interest at 5.3% annually	$	250,000	$	250,000
	Revolving credit agreement, maximum outstanding borrowings of $200 million permitted, expires in 2016	—		—
		$	250,000	$	250,000
	Covenant Compliance
	There are no financial covenants associated with the Senior Notes due 2023.
	The Revolving credit agreement (the Agreement) contains customary representations, covenants and events constituting default, and remedies for default. The Agreement also defines financial covenants regarding permitted leverage ratios and minimum net worth. ProAssurance is currently in compliance with all covenants of the Agreement.
	Additional Information
	For additional information regarding ProAssurance's long-term debt, see Note 10 of the Notes to Consolidated Financial Statements included in ProAssurance's December 31, 2013 Form 10-K.

Shareholders_Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Shareholders' Equity	'
	Shareholders’ Equity
	At September 30, 2014 and December 31, 2013, 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 $0.30 per share during each of the first three quarters of 2014, totaling $52.9 million, which included the third quarter dividend of $17.3 million that was paid in October 2014. ProAssurance declared cash dividends of $0.25 per share during each of the first three quarters of 2013, totaling $46.4 million, which included the third quarter dividend of $15.5 million that was paid in October 2013. The liability for unpaid dividends was included in Other liabilities. Though dividends are typically paid in the month following the quarter in which they were declared, no dividends were paid in the first quarter of 2013 because payment of the regular fourth quarter 2012 dividend was accelerated into December 2012.
	At September 30, 2014, Board authorizations for the repurchase of common shares or the retirement of outstanding debt of $136.7 million remained available for use. ProAssurance repurchased approximately 3.7 million and 0.2 million shares, having a total cost of $167.2 million and $8.0 million, during the nine months ended September 30, 2014 and 2013, respectively.
	Share-based compensation expense was $2.4 million and $8.0 million for the three and nine months ended September 30, 2014, respectively, and $2.2 million and $6.9 million for the three and nine months ended September 30, 2013, respectively. Related tax benefits were $0.8 million and $2.8 million for the three and nine months ended September 30, 2014, respectively, and $0.8 million and $2.4 million for the three and nine months ended September 30, 2013, respectively.
	ProAssurance awarded approximately 50,000 restricted share units and 161,000 base performance share units to employees in February 2014. The fair value of each unit awarded was estimated at $46.34, equal to the market value of a ProAssurance common share on the date of grant. 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 75% to 125% of base awards depending upon the degree to which stated performance objectives are achieved. ProAssurance issued approximately 29,000 and 111,000 common shares to employees in February 2014 related to restricted share units and performance share units, respectively, granted in 2011. Shares issued for performance share units were awarded at the maximum level (125%).
	ProAssurance issued approximately 30,000 common shares to employees in February 2014 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) (OCI)
	For the three and nine months ended September 30, 2014 and September 30, 2013, OCI was primarily comprised of unrealized gains and losses arising during the period related to available-for-sale securities, less reclassification adjustments as shown in the table below, net of tax. At September 30, 2014 and December 31, 2013, accumulated other comprehensive income was comprised primarily of unrealized gains and losses from available-for-sale securities, including non-credit impairment losses previously recognized in OCI of $0.8 million and 0.5 million, respectively, net of tax. All tax effects were computed using a 35% rate. OCI and accumulated other comprehensive income also included immaterial amounts of foreign currency translation adjustments.
	Amounts reclassified from accumulated other comprehensive income to net income and the amounts of deferred tax expense (benefit) included in OCI were as follows:
		Three Months Ended September 30						Nine Months Ended September 30
	(In thousands)	2014			2013			2014			2013
	Reclassifications from accumulated other comprehensive income to net income, available-for-sale securities:
	Realized investment gains (losses)	$	(473	)	$	2,403		$	2,133		$	8,638
	Non-credit impairment losses reclassified to earnings, due to sale of securities or reclassification as a credit loss	—			—			—			(347		)
	Total amounts reclassified, before tax effect	(473		)	2,403			2,133			8,291
	Tax effect (at 35%)	166			(841		)	(747		)	(2,902		)
	Net reclassification adjustments	$	(307	)	$	1,562		$	1,386		$	5,389
	Deferred tax expense (benefit) included in OCI	$	(5,126	)	$	(1,746	)	$	(2,571	)	$	(26,358	)

Variable_Interest_Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2014
Variable Interest Entities [Abstract]	'
Variable Interest Entities	'
	Variable Interest Entities
	ProAssurance holds passive interests in a number of entities that are considered to be Variable Interest Entities (VIEs) under GAAP guidance. ProAssurance's VIE interests principally consist of interests in LPs/LLCs formed for the purpose of achieving diversified equity and debt returns. ProAssurance VIE interests carried as a part of Other investments totaled $37.6 million at September 30, 2014 and $27.3 million at December 31, 2013. ProAssurance VIE interests carried as a part of Investment in unconsolidated subsidiaries totaled $58.1 million at September 30, 2014 and $49.5 million at December 31, 2013.
	ProAssurance has not consolidated these VIEs because it has either very limited or no power to control the activities that most significantly affect the economic performance of these entities and is not the primary beneficiary of any of the entities. ProAssurance’s involvement with each entity is limited to its direct ownership interest in the entity. ProAssurance has no arrangements with any of the entities to provide other financial support to or on behalf of the entity. At September 30, 2014, 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	9 Months Ended
	Sep. 30, 2014
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 dilutive stock options have been exercised and that performance, restricted and purchase share units have vested. All outstanding stock options, performance, restricted and purchase share units had a dilutive effect for the three and nine months ended September 30, 2014 and 2013.

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2014
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 and life sciences products liability insurance. The professional liability business primarily offers professional liability insurance to healthcare providers and institutions and to attorneys and their firms. The medical technology and life sciences business offers products liability insurance for medical technology and life sciences companies that manufacture or distribute products. The Specialty P&C segment cedes certain premium to the Lloyd's Syndicate segment under an agreement with Syndicate 1729. As discussed below, Syndicate 1729 operating results are reported on a quarter delay. The ceded premium associated with the Syndicate 1729 reinsurance agreement has been reported within the Specialty P&C segment on a similar lag, as this results in the ceded premium being reported in the same period in which the Lloyd's Syndicate segment reports the corresponding assumed premium.
	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 a captive insurer unaffiliated with ProAssurance or to SPCs operated by a wholly owned subsidiary of ProAssurance. The SPCs are fully or partially owned by the employer (or employer group, association or affiliate) insured by the policies ceded. Financial results (underwriting profit or loss, plus investment income) of the SPCs accrue to the owners of that cell. Our workers' compensation segment is comprised entirely of the business acquired through Eastern on January 1, 2014.
	Lloyd's Syndicate includes operating results from ProAssurance's 58% participation in Lloyd's of London Syndicate 1729 that began writing business as of January 1, 2014. Syndicate 1729 underwrites risks over a wide range of property and casualty insurance and reinsurance lines. The results of this segment are reported on a quarter delay, except that investment results associated with the FAL investments and certain U.S. paid administrative expenses, primarily start-up costs, are reported concurrently as that information is available on an earlier time frame.
	Corporate includes ProAssurance's U.S. investment operations, interest expense and U.S. income taxes, all of which are managed at the corporate level, 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, 2013 report on Form 10-K and Note 1 herein. ProAssurance evaluates performance of its Specialty P&C and Workers' Compensation segments based on before tax underwriting profit or loss, and excludes investment performance. Performance of the Lloyd's Syndicate segment is evaluated based on underwriting profit or loss, and investment results of investment assets solely allocated to Syndicate 1729 operations, net of United Kingdom 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 sales and transfers as if the sales or transfers were to third parties at current market prices. Assets are not allocated to segments because investments and assets are not managed at the segment level.
	Financial data by segment for the three and nine months ended September 30, 2014 and 2013 were as follows:
		Three Months Ended September 30, 2014
	(In thousands)	Specialty P&C			Workers' Compensation			Lloyd's Syndicate			Corporate			Eliminations			Consolidated
	Net premiums earned	$	123,791		$	49,792		$	3,445		$	—		$	—		$	177,028
	Net investment income	—			—			120			32,710			—			32,830
	Equity in earnings (loss) of unconsolidated subsidiaries	—			—			—			298			—			298
	Net realized gains (losses)	—			—			—			(8,131		)	—			(8,131		)
	Other income	1,071			179			(79		)	824			(187		)	1,808
	Net losses and loss adjustment expenses	(63,639		)	(33,046		)	(2,537		)	—			—			(99,222		)
	Underwriting, policy acquisition and operating expenses	(33,814		)	(14,785		)	(2,584		)	(3,189		)	187			(54,185		)
	Segregated portfolio cells dividend expense	—			483			—			—			—			483
	Interest expense	—			—			—			(3,606		)	—			(3,606		)
	Income tax expense (benefit)	—			—			—			(12,525		)	—			(12,525		)
	Segment operating results	$	27,409		$	2,623		$	(1,635	)	$	6,381		$	—		$	34,778
	Significant non-cash items
	Depreciation and amortization	$	2,334		$	1,602		$	157		$	8,219		$	—		$	12,312
		Nine Months Ended September 30, 2014
	(In thousands)	Specialty P&C			Workers' Compensation			Lloyd's Syndicate			Corporate			Eliminations			Consolidated
	Net premiums earned	$	374,704		$	143,960		$	6,397		$	—		$	—		$	525,061
	Net investment income	—			—			244			92,544			—			92,788
	Equity in earnings (loss) of unconsolidated subsidiaries	—			—			—			2,767			—			2,767
	Net realized gains (losses)	—			—			—			7,659			—			7,659
	Other income	4,167			503			(79		)	1,856			(392		)	6,055
	Net losses and loss adjustment expenses	(191,263		)	(91,975		)	(4,405		)	—			—			(287,643		)
	Underwriting, policy acquisition and operating expenses	(101,044		)	(45,379		)	(5,999		)	(6,826		)	392			(158,856		)
	Segregated portfolio cells dividend expense	—			(2,355		)	—			—			—			(2,355		)
	Interest expense	—			—			—			(10,697		)	—			(10,697		)
	Income tax expense (benefit)	—			—			—			(43,328		)	—			(43,328		)
	Segment operating results	$	86,564		$	4,754		$	(3,842	)	$	43,975		$	—		$	131,451
	Significant non-cash items
	Depreciation and amortization	$	6,708		$	4,384		$	329		$	24,865		$	—		$	36,286
		Three Months Ended September 30, 2013
	(In thousands)	Specialty P&C			Workers' Compensation			Lloyd's Syndicate			Corporate			Eliminations			Consolidated
	Net premiums earned	$	133,598		$	—		$	—		$	—		$	—		$	133,598
	Net investment income	—			—			—			33,889			—			33,889
	Equity in earnings (loss) of unconsolidated subsidiaries	—			—			—			(305		)	—			(305		)
	Net realized gains (losses)	—			—			—			12,500			—			12,500
	Other income	1,225			—			—			579			—			1,804
	Gain on acquisition	—			—			—			494			—			494
	Net losses and loss adjustment expenses	(61,637		)	—			—			—			—			(61,637		)
	Underwriting, policy acquisition and operating expenses	(30,708		)	—			—			(2,640		)	—			(33,348		)
	Interest expense	—			—			—			(322		)	—			(322		)
	Income tax expense (benefit)	—			—			—			(23,316		)	—			(23,316		)
	Segment operating results	$	42,478		$	—		$	—		$	20,879		$	—		$	63,357
	Significant non-cash items
	Depreciation and amortization	$	990		$	—		$	—		$	8,930		$	—		$	9,920
		Nine Months Ended September 30, 2013
	(In thousands)	Specialty P&C			Workers' Compensation			Lloyd's Syndicate			Corporate			Eliminations			Consolidated
	Net premiums earned	$	398,528		$	—		$	—		$	—		$	—		$	398,528
	Net investment income	—			—			—			99,282			—			99,282
	Equity in earnings (loss) of unconsolidated subsidiaries	—			—			—			(3,500		)	—			(3,500		)
	Net realized gains (losses)	—			—			—			47,650			—			47,650
	Other income	3,902			—			—			1,410			(7		)	5,305
	Gain on acquisition	—			—			—			35,986			—			35,986
	Net losses and loss adjustment expenses	(189,872		)	—			—			—			—			(189,872		)
	Underwriting, policy acquisition and operating expenses	(95,907		)	—			—			(9,692		)	7			(105,592		)
Interest expense	—			—			—			(1,085		)	—			(1,085		)
Income tax expense (benefit)	—			—			—			(60,044		)	—			(60,044		)
Segment operating results	$	116,651		$	—		$	—		$	110,007		$	—		$	226,658
Significant non-cash items
Depreciation and amortization	$	4,845		$	—		$	—		$	29,519		$	—		$	34,364
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 United States.
	Three Months Ended September 30						Nine Months Ended September 30
(In thousands)	2014			2013			2014			2013
Specialty P&C Segment
Gross premiums earned:
Healthcare professional liability	$	120,623		$	128,532		$	361,179		$	382,678
Legal professional liability	7,145			6,849			21,147			20,328
Medical technology and life sciences products liability	9,258			8,436			27,043			24,442
Other	420			463			1,445			1,336
Ceded premiums earned*	(13,655		)	(10,682		)	(36,110		)	(30,256		)
Segment net premiums earned	$	123,791		$	133,598		$	374,704		$	398,528
Workers' Compensation Segment
Gross premiums earned:
Traditional business	$	42,345		$	—		$	119,702		$	—
Alternative market business	14,345			—			40,253			—
Ceded premiums earned	(6,898		)	—			(15,995		)	—
Segment net premiums earned	$	49,792		$	—		$	143,960		$	—
Lloyd's Syndicate Segment
Gross premiums earned:
Property and casualty*	$	4,085		$	—		$	7,110		$	—
Ceded premiums earned	(640		)	—			(713		)	—
Segment net premiums earned	$	3,445		$	—		$	6,397		$	—
Consolidated net premiums earned	$	177,028		$	133,598		$	525,061		$	398,528
* Includes premium ceded from the Specialty P&C Segment to the Lloyd's Syndicate Segment of $1.1 million for the three months and $1.6 million for nine months ended September 30, 2014, respectively.

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Reclassifications	'
	Reclassifications
	On January 1, 2014, ProAssurance began reporting unearned ceding commissions as an offset to deferred policy acquisition costs (DPAC) on the Condensed Consolidated Balance Sheet, and the December 31, 2013 Condensed Consolidated Balance Sheet has been conformed to the current presentation. Previously, unearned ceding commissions ($0.8 million at December 31, 2013) were reported in Unearned premiums. Also, ceding commission income earned for the three and nine months ended September 30, 2014 and 2013 has been reported as an offset to DPAC amortization (see Note 6) which lowered DPAC amortization as previously reported for the three and nine months ended September 30, 2013 by $1.5 million and $4.2 million, respectively. Total underwriting, policy acquisition and operating expense for the 2013 three- and nine-month periods was not affected by the change in presentation.
Intangible Assets	'
	Intangible Assets
	Intangible assets with definite lives are amortized over the estimated useful life of the asset. Amortizable intangible assets primarily consist of agency and policyholder relationships, renewal rights and trade names and had a carrying value of $77.5 million at September 30, 2014 and $35.2 million at December 31, 2013. Intangible assets with an indefinite life, primarily state licenses, are not amortized and had carrying values of $25.8 million at September 30, 2014 and $16.8 million at December 31, 2013. Both amortizable and non-amortizable intangible assets increased during 2014 due to intangible assets purchased in the Eastern acquisition, see Note 2. Intangible assets are evaluated for impairment on an annual basis.
Other Assets and Other Liabilities	'
	Other Assets and Other Liabilities
	At December 31, 2013, Other assets was principally comprised of a deposit with an intermediate third-party of $205 million, related to the completion of the Eastern Insurance Holdings, Inc. (Eastern) acquisition which closed on January 1, 2014. See Note 2.
	At September 30, 2014, Other liabilities included $16.5 million in segregated portfolio cell (SPC) dividends payable related to our recently acquired Workers' Compensation segment. The SPC dividend payable represents the cumulative undistributed earnings of segregated portfolio cells that are contractually payable to external preferred shareholders of the cells.
Earned But Unbilled Premiums (EBUB)	'
	Earned But Unbilled Premiums (EBUB)
	Workers’ compensation premiums are determined based upon the payroll of the insured, the applicable premium rates and, where applicable, an experience based modification factor. An audit of the policyholders’ records is conducted after policy expiration to make a final determination of applicable premiums. Audit premium due from or due to a policyholder as a result of an audit is reflected in net premiums earned when billed. ProAssurance tracks, by policy, the amount of additional premium billed in final audit invoices as a percentage of payroll exposure and uses this information to estimate the probable additional amount that it has earned, but not yet billed, as of the balance sheet date. Changes to the EBUB estimate are included in Net premiums earned in the period recognized.
Convertible Bond Securities	'
	Convertible Bond Securities
	Investments in convertible bond 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. Interest on convertible bond securities is recorded on an accrual basis based on contractual interest rates and is included in Net investment income.
Foreign Currency	'
	Foreign Currency
	The functional currency of all ProAssurance foreign subsidiaries is the U.S. Dollar.
Accounting Changes Not Yet Adopted and Adopted	'
	Accounting Changes Not Yet Adopted
	Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity
	Effective for fiscal years beginning after December 15, 2014, the Financial Accounting Standards Board (FASB) issued guidance which changes the requirements for reporting discontinued operations. Under the new guidance, reporting entities are required to report disposals of business components only if the disposal represents a strategic shift in the entity’s operations that will have a major effect on the entity’s operations and financial results. The new guidance expands disclosure requirements for reported discontinued operations and requires disclosure of pre-tax profit or loss attributable to significant disposals that are not reported as discontinued operations. ProAssurance plans to adopt the guidance beginning January 1, 2015. Adoption of the guidance is expected to have no effect on ProAssurance’s results of operations or financial position.
	Equity Method and Joint Ventures-Accounting for Investments in Qualified Affordable Housing Projects
	Effective for fiscal years beginning after December 15, 2014, the FASB issued guidance which permits but does not require qualified reporting entities to use a new accounting method, the proportional amortization method, for investments in qualified affordable housing projects, also referred to as low income housing projects. Under the new method the initial cost of an investment is amortized in proportion to the tax benefits received, and investment performance is recognized as a component of income tax expense (benefit) rather than as a component of investment income. ProAssurance is in the process of evaluating whether it meets the qualification requirements for using the new method and the effect that the use of the new method would have on its results of operations and financial position. If ProAssurance elects to adopt the new method, the adoption will occur beginning January 1, 2015.
	Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period
	Effective for fiscal years beginning after December 15, 2015, the FASB issued guidance for share-based payments in which the terms of the award provide that a performance target can be achieved after completion of the requisite service period. The new guidance provides that compensation cost for such awards should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. ProAssurance plans to adopt the guidance beginning January 1, 2016. Adoption of the guidance is expected to have no effect on ProAssurance’s results of operations or financial position as ProAssurance has no awards with performance targets extending beyond the requisite service period.
	Revenue from Contracts with Customers
	Effective for fiscal years beginning after December 15, 2016, the FASB issued guidance related to revenue from contracts with customers. The core principle of the new guidance is that revenue should be 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, 2017. 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 expected to have no material effect on ProAssurance’s results of operations or financial position.
	Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern
	Effective for fiscal years ending after December 15, 2016 and interim periods beginning after December 15, 2016, the FASB issued guidance that establishes principles and definitions related to management's evaluation of whether there is substantial doubt about the organization's ability to continue as a going concern. For each interim and annual reporting period, the new guidance requires management to evaluate the organization's ability to meet its obligations as they are due within one year of the date the financial statements are issued and requires disclosure when there is substantial doubt regarding the organization's ability to continue as a going concern. ProAssurance plans to adopt the guidance beginning December 15, 2016. Adoption is expected to have no effect on ProAssurance’s results of operations or financial position.
	Accounting Changes Adopted
	Obligations Resulting from Joint and Several Liability Arrangements
	Effective for fiscal years beginning after December 15, 2013, the FASB revised guidance related to obligations resulting from joint and several liability arrangements. The new guidance requires an entity to recognize, measure and disclose obligations resulting from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date, except for obligations already addressed within existing GAAP guidance, with retrospective application required for such arrangements existing at the beginning of the fiscal year of adoption. ProAssurance adopted the guidance on January 1, 2014. Adoption of this guidance had no effect on ProAssurance's results of operations or financial position.
	Presentation of Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists
	Effective for fiscal years beginning after December 15, 2013, the FASB issued guidance related to the financial statement presentation of unrecognized tax benefits. The new guidance requires an entity to present unrecognized tax benefits as a reduction to a deferred tax asset resulting from a net operating loss carryforward, a similar tax loss, or tax credit carryforward except in circumstances where the relevant taxing authority does not permit offset or does not require offset and the entity does not intend to use the deferred tax asset for offset. The guidance requires prospective application for all unrecognized tax benefits that exist as of the effective date, but may be applied retrospectively. ProAssurance adopted the guidance prospectively on January 1, 2014. Adoption of this guidance had no material effect on ProAssurance's results of operations or financial position.

Business_Combinations_Tables

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Purchase price allocation	'
	The purchase consideration for Eastern was allocated to the assets acquired and liabilities assumed based on their estimated fair values on the acquisition date. Goodwill of $49.6 million was recognized equal to the excess of the purchase price over the net fair value of identifiable assets acquired and liabilities assumed. Factors contributing to the recognition of goodwill include strategic and synergistic benefits that are expected to be realized as a result of the acquisition. These benefits include insurance market diversification, expanded access to alternative markets, and opportunities to reach additional insureds in the healthcare market by being a single source provider of a suite of insurance products. None of the goodwill is expected to be tax deductible. The allocation of purchase consideration is shown in the table below.
	(In thousands)
	Fixed maturities, available for sale		$	107,131
	Equity securities, trading		65,945
	Cash and short-term investments		58,944
	Other investments		42,133
	Premiums receivable		71,989
	Receivable from reinsurers on paid and unpaid losses and LAE		18,942
	Intangible assets		59,000
	Deferred policy acquisition costs (see discussion below)		10,593
	Other assets		19,225
	Reserve for losses and loss adjustment expenses		(153,191		)
	Unearned premiums		(80,268		)
	Ceded balances payable		(9,507		)
	Segregated portfolio cells dividends payable		(14,430		)
	Deferred tax liabilities, net		(12,835		)
	Other liabilities		(28,038		)
	Fair value of net assets acquired		$	155,633
	Goodwill		49,610
	Total purchase consideration		$	205,243
Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination	'
	Intangible assets acquired included the following:
	(In millions)	Estimated Fair Value on Acquisition Date		Estimated Useful Life
	Agency relationships	$27.00		15
	Policyholder relationships	8		15
	Trade names	8		15
	Non-compete agreements	7		3
	Total intangibles subject to amortization	$50.00		13	*
	Insurance license agreements	$9.00		Indefinite
	* Reflects the weighted average estimated useful life of acquired intangible assets that are subject to amortization.
ProAssurance Consolidated results	'
	The following table provides Pro Forma Consolidated Results for the three and nine months ended September 30, 2014 and 2013 as if the Eastern transaction had occurred on January 1, 2013. ProAssurance Actual Consolidated Results have been adjusted by the following, net of related tax effects, to reflect the Pro Forma Consolidated Results below.
	•	For the three and nine months ended September 30, 2013, ProAssurance 2013 Actual Consolidated Results, which did not include Eastern, have been adjusted to include Eastern's 2013 operating results. ProAssurance Actual Consolidated Results for the three and nine months ended September 30, 2014 included Eastern's operating results (Revenue of $49.6 million and $149.9 million, respectively, and Net income of $1.7 million and $7.1 million, respectively).
	•	Certain costs included in ProAssurance actual results for the three and nine months ended September 30, 2014 have been reported in the Pro Forma Consolidated Results as if the costs had been incurred for the three and nine months ended September 30, 2013. Such costs include direct transaction costs and certain compensation costs directly related to the integration of Eastern operations.
	•	Actual Consolidated Results for the three and nine months ended September 30, 2013, were reduced to reflect amortization of intangible assets and debt security premiums and discounts recorded as a part of the Eastern purchase price allocation.
		Three Months Ended September 30, 2014				Nine Months Ended September 30, 2014
	(In thousands)	ProAssurance		ProAssurance		ProAssurance	ProAssurance
		Pro Forma		Actual		Pro Forma	Actual
		Consolidated		Consolidated Results		Consolidated	Consolidated Results
		Results				Results
	Revenue	$203,833		$203,833		$634,330	$634,330
	Net income	$34,759		$34,778		$132,451	$131,451
		Three Months Ended September 30, 2013				Nine Months Ended September 30, 2013
	(In thousands)	ProAssurance		ProAssurance		ProAssurance	ProAssurance
		Pro Forma		Actual		Pro Forma	Actual
		Consolidated		Consolidated Results		Consolidated	Consolidated Results
		Results				Results
	Revenue	$229,608		$181,486		$686,391	$547,265
	Net income	$66,868		$63,357		$233,666	$226,658

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2014
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 September 30, 2014 and December 31, 2013, including financial instruments for which ProAssurance has elected fair value, are shown in the following tables. 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.
		30-Sep-14
		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	$	—			$	176,813			$	—		$	176,813
	U.S. Government-sponsored enterprise obligations	—				43,966				—			43,966
	State and municipal bonds	—				1,082,040				5,594			1,087,634
	Corporate debt, multiple observable inputs	—				1,459,550				—			1,459,550
	Corporate debt, limited observable inputs:
	Other corporate debt, NRSRO ratings available	—				—				10,793			10,793
	Other corporate debt, NRSRO ratings not available	—				—				2,642			2,642
	Residential mortgage-backed securities	—				290,314				—			290,314
	Agency commercial mortgage-backed securities	—				16,893				—			16,893
	Other commercial mortgage-backed securities	—				57,323				—			57,323
	Other asset-backed securities	—				96,119				4,773			100,892
	Equity securities
	Financial	75,141				—				—			75,141
	Utilities/Energy	26,551				—				—			26,551
	Consumer oriented	64,912				—				—			64,912
	Industrial	54,912				—				—			54,912
	Bond funds	53,178				—				—			53,178
	All other	31,937				—				—			31,937
	Short-term investments	94,323				650				—			94,973
	Financial instruments carried at fair value, classified as a part of:
	Investment in unconsolidated subsidiaries	—				—				110,793			110,793
	Other investments	4,830				25,228				—			30,058
	Total assets	$	405,784			$	3,248,896			$	134,595		$	3,789,275
		31-Dec-13
		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	$	—			$	170,714			$	—		$	170,714
	U.S. Government-sponsored enterprise obligations	—				32,768				—			32,768
	State and municipal bonds	—				1,147,328				7,338			1,154,666
	Corporate debt, multiple observable inputs	—				1,346,977				—			1,346,977
	Corporate debt, limited observable inputs:
	Other corporate debt, NRSRO ratings available	—				—				11,449			11,449
	Other corporate debt, NRSRO ratings not available	—				—				2,727			2,727
	Residential mortgage-backed securities	—				235,614				—			235,614
	Agency commercial mortgage-backed securities	—				27,475				—			27,475
	Other commercial mortgage-backed securities	—				61,390				—			61,390
	Other asset-backed securities	—				67,455				6,814			74,269
	Equity securities
	Financial	81,536				—				—			81,536
	Utilities/Energy	32,350				—				—			32,350
	Consumer oriented	66,461				—				—			66,461
	Industrial	57,262				—				—			57,262
	All other	15,932				—				—			15,932
	Short-term investments	248,605											248,605
	Financial instruments carried at fair value, classified as a part of:
	Investment in unconsolidated subsidiaries	—				—				72,062			72,062
	Total assets	$	502,146			$	3,089,721			$	100,390		$	3,692,257
Investments in Limited liability companies and limited partnerships	'
	Investment in unconsolidated subsidiaries consisted of limited partnership (LP) and limited liability company (LLC) interests valued using the NAV provided by the LP/LLC, which approximated the fair value of the interest.
	Such interests include the following:
		Unfunded		Fair Value
		Commitments
	(In thousands)	September 30,		September 30,				December 31,
		2014		2014				2013
	Investments in LPs/LLCs:
	Secured debt fund (1)	$16,200		$	23,896			$	13,233
	Long equity fund (2)	None		7,034				6,574
	Long/Short equity funds (3)	None		25,016				28,385
	Non-public equity funds (4)	$71,518		42,818				23,870
	Multi-strategy fund of funds (5)	None		8,263				—
	Structured credit fund (6)	None		3,766				—
				$	110,793			$	72,062
	-1	The LP is structured to provide income and capital appreciation primarily through investments in senior secured debt. Redemptions are not allowed. Income and capital are to be periodically distributed at the discretion of the LP over an anticipated time frame that spans from 7 to 9 years.
	-2	The LP 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	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 event-driven market opportunities. The funds generally permit quarterly or semi-annual redemptions of the investors’ existing capital balance with 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	Comprised of interests in three 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 LPs. One LP allows redemption by special consent; 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 from 4 to 12 years.
	-5	The LLC is 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 the LLC Board is permitted discretion to periodically extend offers to repurchase units of the LLC.
	-6	The LP seeks 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.
Summary of quantitative information about Level 3 fair value measurements	'
	Quantitative Information Regarding Level 3 Valuations
	Quantitative Information about Level 3 Fair Value Measurements
			Fair Value at
	(In millions)		30-Sep-14		31-Dec-13		Valuation Technique		Unobservable Input		Range
											(Weighted Average)
	Assets:
	State and municipal bonds		$5.60		$7.30		Market Comparable		Comparability Adjustment		0% - 10% (5%)
							Securities
							Discounted Cash Flows		Comparability Adjustment		0% - 10% (5%)
	Corporate debt with limited observable inputs		$13.40		$14.20		Market Comparable		Comparability Adjustment		0% - 5% (2.5%)
							Securities
							Discounted Cash Flows		Comparability Adjustment		0% - 5% (2.5%)
	Other asset-backed securities		$4.80		$6.80		Market Comparable		Comparability Adjustment		0% - 5% (2.5%)
							Securities
							Discounted Cash Flows		Comparability Adjustment		0% - 5% (2.5%)
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.
		30-Sep-14
		Level 3 Fair Value Measurements – Assets
	(In thousands)	U.S. Government-sponsored Enterprise Obligations				State and Municipal Bonds				Corporate Debt			Asset-backed Securities			Investment in Unconsolidated Subsidiaries			Total
	Balance June 30, 2014	$	—			$	7,148			$	14,544		$	5,960		$	101,342		$	128,994
	Total gains (losses) realized and unrealized:
	Included in earnings, as a part of:
	Net investment income	—				(4		)		16			—			—			12
	Equity in earnings of unconsolidated subsidiaries	—				—				—			—			(683		)	(683		)
	Net realized investment gains (losses)	—				—				—			—			—			—
	Included in other comprehensive income	—				(76		)		35			(6		)	—			(47		)
	Purchases	—				—				(499		)	—			12,055			11,556
	Sales	—				(1,474		)		(661		)	—			(1,921		)	(4,056		)
	Transfers in	—				—				—			—			—			—
	Transfers out	—				—				—			(1,181		)	—			(1,181		)
	Balance September 30, 2014	$	—			$	5,594			$	13,435		$	4,773		$	110,793		$	134,595
	Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	$	—			$	—			$	—		$	—		$	(683	)	$	(683	)
		30-Sep-14
		Level 3 Fair Value Measurements – Assets
	(In thousands)	U.S. Government-sponsored Enterprise Obligations				State and Municipal Bonds				Corporate Debt			Asset-backed Securities			Investment in Unconsolidated Subsidiaries			Total
	Balance December 31, 2013	$	—			$	7,338			$	14,176		$	6,814		$	72,062		$	100,390
	Total gains (losses) realized and unrealized:
	Included in earnings, as a part of:
	Net investment income	—				(10		)		48			—			—			38
	Equity in earnings of unconsolidated subsidiaries	—				—				—			—			5,413			5,413
	Net realized investment gains (losses)	—				(95		)		3			—			—			(92		)
	Included in other comprehensive income	1				(34		)		702			63			—			732
	Purchases	1,000				1,861				2,000			3,340			37,430			45,631
	Sales	—				(1,731		)		(1,469		)	(61		)	(4,112		)	(7,373		)
	Transfers in	—				2,119				—			305			—			2,424
	Transfers out	(1,001		)		(3,854		)		(2,025		)	(5,688		)	—			(12,568		)
	Balance September 30, 2014	$	—			$	5,594			$	13,435		$	4,773		$	110,793		$	134,595
	Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	$	—			$	—			$	—		$	—		$	5,413		$	5,413
		30-Sep-13
		Level 3 Fair Value Measurements – Assets
	(In thousands)	U.S. Government-sponsored Enterprise Obligations				State and Municipal Bonds				Corporate Debt			Asset-backed Securities			Investment in Unconsolidated Subsidiaries			Total
	Balance June 30, 2013	$	—			$	5,025			$	11,359		$	4,679		$	44,549		$	65,612
	Total gains (losses) realized and unrealized:
	Included in earnings, as a part of:
	Net investment income	—				—				(1		)	—			—			(1		)
	Equity in earnings of unconsolidated subsidiaries	—				—				—			—			1,301			1,301
	Net realized investment gains (losses)	—				—				—			—			—			—
	Included in other comprehensive income	—				—				(221		)	16			—			(205		)
	Purchases	—				—				—			—			2,354			2,354
	Sales	—				—				(503		)	—			(3,548		)	(4,051		)
	Transfers in	—				—				100			—			—			100
	Transfers out	—				—				—			—			—			—
	Balance September 30, 2013	$	—			$	5,025			$	10,734		$	4,695		$	44,656		$	65,110
	Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	$	—			$	—			$	—		$	—		$	1,301		$	1,301
		30-Sep-13
		Level 3 Fair Value Measurements – Assets
	(In thousands)	U.S. Government-sponsored Enterprise Obligations				State and Municipal Bonds				Corporate Debt			Asset-backed Securities			Investment in Unconsolidated Subsidiaries			Total
	Balance December 31, 2012	$	—			$	7,175			$	15,191		$	4,035		$	33,739		$	60,140
	Total gains (losses) realized and unrealized:
	Included in earnings, as a part of:
	Net investment income	—				—				(103		)	(17		)	—			(120		)
	Equity in earnings of unconsolidated subsidiaries	—				—				—			—			3,582			3,582
	Net realized investment gains (losses)	—				(44		)		(69		)	—			—			(113		)
	Included in other comprehensive income	—				—				(514		)	(81		)	—			(595		)
	Purchases	—				—				7,470			1,356			20,975			29,801
	Sales	—				(2,106		)		(1,368		)	(18		)	(13,640		)	(17,132		)
	Transfers in	—				—				100			1,701			—			1,801
	Transfers out	—				—				(9,973		)	(2,281		)	—			(12,254		)
Balance September 30, 2013	$	—			$	5,025			$	10,734		$	4,695		$	44,656		$	65,110
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	$	—			$	—			$	—		$	—		$	3,582		$	3,582
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.
		30-Sep-14								31-Dec-13
	(In thousands)	Carrying				Fair				Carrying			Fair
		Value				Value				Value			Value
	Financial assets:
	BOLI	$	55,918			$	55,918			$	54,374		$	54,374
	Other investments	61,952				63,247				52,240			51,833
	Other assets	21,298				21,248				17,940			17,940
	Financial liabilities:
	Senior notes due 2023	$	250,000			$	273,750			$	250,000		$	262,500
	Other liabilities	14,022				14,139				13,303			13,303

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 30, 2014
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 September 30, 2014 and December 31, 2013 included the following:
		30-Sep-14
	(In thousands)	Amortized				Gross Unrealized Gains			Gross Unrealized Losses			Estimated Fair Value
		Cost
	Fixed maturities
	U.S. Treasury obligations	$	173,632			$	4,396		$	1,215		$	176,813
	U.S. Government-sponsored enterprise obligations	42,480				1,709			223			43,966
	State and municipal bonds	1,038,278				50,055			699			1,087,634
	Corporate debt	1,433,266				48,894			9,175			1,472,985
	Residential mortgage-backed securities	282,717				8,817			1,220			290,314
	Agency commercial mortgage-backed securities	16,785				172			64			16,893
	Other commercial mortgage-backed securities	55,853				1,587			117			57,323
	Other asset-backed securities	100,715				346			169			100,892
		$	3,143,726			$	115,976		$	12,882		$	3,246,820
		31-Dec-13
	(In thousands)	Amortized				Gross Unrealized Gains			Gross Unrealized Losses			Estimated Fair Value
		Cost
	Fixed maturities
	U.S. Treasury obligations	$	166,115			$	6,118		$	1,519		$	170,714
	U.S. Government-sponsored enterprise obligations	30,942				2,251			425			32,768
	State and municipal bonds	1,116,060				46,533			7,927			1,154,666
	Corporate debt	1,321,838				53,059			13,744			1,361,153
	Residential mortgage-backed securities	230,861				7,608			2,855			235,614
	Agency commercial mortgage-backed securities	27,268				343			136			27,475
	Other commercial mortgage-backed securities	59,066				2,491			167			61,390
	Other asset-backed securities	74,106				487			324			74,269
		$	3,026,256			$	118,890		$	27,097		$	3,118,049
Schedule of available for sale securities by contractual maturity	'
	The recorded cost basis and estimated fair value of available-for-sale fixed maturities at September 30, 2014, 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
		Cost				year or less			one year			five years			ten years		Value
									through			through
									five years			ten years
	Fixed maturities, available for sale
	U.S. Treasury obligations	$	173,632			$	19,612		$	104,211		$	48,950		$	4,040	$	176,813
	U.S. Government-sponsored enterprise obligations	42,480				8,002			25,465			10,160			339		43,966
	State and municipal bonds	1,038,278				49,169			393,569			442,212			202,684		1,087,634
	Corporate debt	1,433,266				157,683			694,254			598,183			22,865		1,472,985
	Residential mortgage-backed securities	282,717															290,314
	Agency commercial mortgage-backed securities	16,785															16,893
	Other commercial mortgage-backed securities	55,853															57,323
	Other asset-backed securities	100,715															100,892
		$	3,143,726														$	3,246,820
Other Investments	'
	Other investments at September 30, 2014 and December 31, 2013 was comprised as follows:
	(In thousands)	September 30,				December 31,
		2014				2013
	Investments in LPs/LLCs, at cost	$	57,607			$	47,258
	Convertible securities, at fair value, see Note 1	30,058				—
	Other, principally FHLB capital stock, at cost	4,345				4,982
		$	92,010			$	52,240
Unconsolidated Subsidiaries	'
	ProAssurance holds investments in unconsolidated subsidiaries, accounted for under the equity method. The investments include the following:
		30-Sep-14					Carrying Value
	(In thousands)	Unfunded		Percentage			September 30,			December 31,
		Commitments*		Ownership			2014			2013
	Investment in LPs/LLCs:
	Tax credit partnerships	$15,710		See below			$	137,386		$	142,174
	Secured debt fund	$16,200		<	20%		23,896			13,233
	Long equity fund	None		<	20%		7,034			6,574
	Long/short equity funds	None		<	25%		25,016			28,385
	Non-public equity funds	$88,034		<	20%		46,127			23,870
	Multi-strategy fund of funds	None		<	20%		8,263			—
	Structured credit fund	None		<	20%		3,766			—
	Real estate fund	$6,526		<	20%		3,474			—
							$	254,962		$	214,236
	* Unfunded commitments are included in the carrying value of tax credit partnerships only.
Investments held in an unrealized loss position	'
	The following tables provide summarized information with respect to investments held in an unrealized loss position at September 30, 2014 and December 31, 2013, including the length of time the investment had been held in a continuous unrealized loss position.
		30-Sep-14
		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	$	59,770			$	1,215		$	37,309		$	534		$	22,461	$	681
	U.S. Government-sponsored enterprise obligations	7,887				223			2,136			22			5,751		201
	State and municipal bonds	71,155				699			32,129			128			39,026		571
	Corporate debt	477,806				9,175			372,670			5,909			105,136		3,266
	Residential mortgage-backed securities	66,143				1,220			26,012			105			40,131		1,115
	Agency commercial mortgage-backed securities	10,432				64			8,536			8			1,896		56
	Other commercial mortgage-backed securities	14,592				117			7,528			33			7,064		84
	Other asset-backed securities	39,328				169			35,269			77			4,059		92
		$	747,113			$	12,882		$	521,589		$	6,816		$	225,524	$	6,066
	Other investments
	Investments in LPs/LLCs carried at cost	$	17,106			$	582		$	15,458		$	577		$	1,648	$	5
		31-Dec-13
		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	$	47,668			$	1,519		$	44,304		$	1,182		$	3,364	$	337
	U.S. Government-sponsored enterprise obligations	6,640				425			5,752			321			888		104
	State and municipal bonds	203,970				7,927			184,401			6,640			19,569		1,287
	Corporate debt	349,277				13,744			324,510			12,061			24,767		1,683
	Residential mortgage-backed securities	93,608				2,855			84,045			2,393			9,563		462
	Agency commercial mortgage-backed securities	11,658				136			11,082			116			576		20
	Other commercial mortgage-backed securities	11,153				167			10,215			159			938		8
	Other asset-backed securities	25,539				324			21,804			77			3,735		247
		$	749,513			$	27,097		$	686,113		$	22,949		$	63,400	$	4,148
	Other investments
	Investments in LPs/LLCs carried at cost	$	14,752			$	1,059		$	13,166		$	1,018		$	1,586	$	41
Net Investment Income	'
	Net investment income by investment category was as follows:
		Three Months Ended							Nine Months Ended
		30-Sep							30-Sep
	(In thousands)	2014				2013			2014			2013
	Fixed maturities	$	28,442			$	30,672		$	85,402		$	93,687
	Equities	2,661				2,394			7,479			7,000
	Short-term investments and Other invested assets	2,793				2,000			4,723			2,514
	Business owned life insurance	646				633			1,544			1,508
	Investment fees and expenses	(1,712		)		(1,810		)	(6,360		)	(5,427		)
	Net investment income	$	32,830			$	33,889		$	92,788		$	99,282
Net realized investment gains (losses)	'
	The following table provides detailed information regarding net realized investment gains (losses):
		Three Months Ended September 30							Nine Months Ended September 30
	(In thousands)	2014				2013			2014			2013
	Total other-than-temporary impairment losses:
	State and municipal bonds	$	—			$	—		$	(50	)	$	(71	)
	Corporate debt	(1,425		)		—			(1,425		)	—
	Portion recognized in (reclassified from) Other Comprehensive Income:
	Corporate debt	268				—			268			—
	Net impairments recognized in earnings	$	(1,157	)		$	—		$	(1,207	)	$	(71	)
	Gross realized gains, available-for-sale securities	736				7,708			3,711			14,631
	Gross realized (losses), available-for-sale securities	(52		)		(5,305		)	(371		)	(6,269		)
	Net realized gains (losses), trading securities	3,227				5,818			21,830			14,650
	Net realized gains (losses), Other investments	55				—			321			—
	Change in unrealized holding gains (losses), trading securities	(10,402		)		3,355			(17,906		)	23,784
	Change in unrealized holding gains (losses), convertible securities, carried at fair value	(538		)		—			1,281			—
	Other	—				924			—			925
	Net realized investment gains (losses)	$	(8,131	)		$	12,500		$	7,659		$	47,650
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 other-than-temporary impairment was recorded in Other comprehensive income.
		Three Months Ended September 30							Nine Months Ended September 30
	(In thousands)	2014				2013			2014			2013
	Balance beginning of period	$	83			$	413		$	83		$	3,301
	Additional credit losses recognized during the period, related to securities for which:
	No OTTI has been previously recognized	149				—			149			—
	Reductions due to:
	Securities sold during the period (realized)	—				(330		)	—			(3,218		)
	Balance September 30	$	232			$	83		$	232		$	83
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 September 30							Nine Months Ended September 30
	(In millions)	2014				2013			2014			2013
	Proceeds from sales (exclusive of maturities and paydowns)	$	24.8			$	319.2		$	147.3		$	494.8
	Purchases	$	146.5			$	98.8		$	511.9		$	406.2

Longterm_Debt_Tables

Long-term Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Schedule of Long-term Debt Instruments	'
	ProAssurance’s outstanding long-term debt consisted of the following:
	(In thousands)	September 30,		December 31,
		2014		2013
	Senior notes due 2023, unsecured, interest at 5.3% annually	$	250,000	$	250,000
	Revolving credit agreement, maximum outstanding borrowings of $200 million permitted, expires in 2016	—		—
		$	250,000	$	250,000

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Reclassification adjustments related to available-for-sale securities	'
	Amounts reclassified from accumulated other comprehensive income to net income and the amounts of deferred tax expense (benefit) included in OCI were as follows:
		Three Months Ended September 30						Nine Months Ended September 30
	(In thousands)	2014			2013			2014			2013
	Reclassifications from accumulated other comprehensive income to net income, available-for-sale securities:
	Realized investment gains (losses)	$	(473	)	$	2,403		$	2,133		$	8,638
	Non-credit impairment losses reclassified to earnings, due to sale of securities or reclassification as a credit loss	—			—			—			(347		)
	Total amounts reclassified, before tax effect	(473		)	2,403			2,133			8,291
	Tax effect (at 35%)	166			(841		)	(747		)	(2,902		)
	Net reclassification adjustments	$	(307	)	$	1,562		$	1,386		$	5,389
	Deferred tax expense (benefit) included in OCI	$	(5,126	)	$	(1,746	)	$	(2,571	)	$	(26,358	)

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Schedule of Segment Reporting Information, by Segment	'
	Financial data by segment for the three and nine months ended September 30, 2014 and 2013 were as follows:
		Three Months Ended September 30, 2014
	(In thousands)	Specialty P&C			Workers' Compensation			Lloyd's Syndicate			Corporate			Eliminations			Consolidated
	Net premiums earned	$	123,791		$	49,792		$	3,445		$	—		$	—		$	177,028
	Net investment income	—			—			120			32,710			—			32,830
	Equity in earnings (loss) of unconsolidated subsidiaries	—			—			—			298			—			298
	Net realized gains (losses)	—			—			—			(8,131		)	—			(8,131		)
	Other income	1,071			179			(79		)	824			(187		)	1,808
	Net losses and loss adjustment expenses	(63,639		)	(33,046		)	(2,537		)	—			—			(99,222		)
	Underwriting, policy acquisition and operating expenses	(33,814		)	(14,785		)	(2,584		)	(3,189		)	187			(54,185		)
	Segregated portfolio cells dividend expense	—			483			—			—			—			483
	Interest expense	—			—			—			(3,606		)	—			(3,606		)
	Income tax expense (benefit)	—			—			—			(12,525		)	—			(12,525		)
	Segment operating results	$	27,409		$	2,623		$	(1,635	)	$	6,381		$	—		$	34,778
	Significant non-cash items
	Depreciation and amortization	$	2,334		$	1,602		$	157		$	8,219		$	—		$	12,312
		Nine Months Ended September 30, 2014
	(In thousands)	Specialty P&C			Workers' Compensation			Lloyd's Syndicate			Corporate			Eliminations			Consolidated
	Net premiums earned	$	374,704		$	143,960		$	6,397		$	—		$	—		$	525,061
	Net investment income	—			—			244			92,544			—			92,788
	Equity in earnings (loss) of unconsolidated subsidiaries	—			—			—			2,767			—			2,767
	Net realized gains (losses)	—			—			—			7,659			—			7,659
	Other income	4,167			503			(79		)	1,856			(392		)	6,055
	Net losses and loss adjustment expenses	(191,263		)	(91,975		)	(4,405		)	—			—			(287,643		)
	Underwriting, policy acquisition and operating expenses	(101,044		)	(45,379		)	(5,999		)	(6,826		)	392			(158,856		)
	Segregated portfolio cells dividend expense	—			(2,355		)	—			—			—			(2,355		)
	Interest expense	—			—			—			(10,697		)	—			(10,697		)
	Income tax expense (benefit)	—			—			—			(43,328		)	—			(43,328		)
	Segment operating results	$	86,564		$	4,754		$	(3,842	)	$	43,975		$	—		$	131,451
	Significant non-cash items
	Depreciation and amortization	$	6,708		$	4,384		$	329		$	24,865		$	—		$	36,286
		Three Months Ended September 30, 2013
	(In thousands)	Specialty P&C			Workers' Compensation			Lloyd's Syndicate			Corporate			Eliminations			Consolidated
	Net premiums earned	$	133,598		$	—		$	—		$	—		$	—		$	133,598
	Net investment income	—			—			—			33,889			—			33,889
	Equity in earnings (loss) of unconsolidated subsidiaries	—			—			—			(305		)	—			(305		)
	Net realized gains (losses)	—			—			—			12,500			—			12,500
	Other income	1,225			—			—			579			—			1,804
	Gain on acquisition	—			—			—			494			—			494
	Net losses and loss adjustment expenses	(61,637		)	—			—			—			—			(61,637		)
	Underwriting, policy acquisition and operating expenses	(30,708		)	—			—			(2,640		)	—			(33,348		)
	Interest expense	—			—			—			(322		)	—			(322		)
	Income tax expense (benefit)	—			—			—			(23,316		)	—			(23,316		)
	Segment operating results	$	42,478		$	—		$	—		$	20,879		$	—		$	63,357
	Significant non-cash items
	Depreciation and amortization	$	990		$	—		$	—		$	8,930		$	—		$	9,920
		Nine Months Ended September 30, 2013
	(In thousands)	Specialty P&C			Workers' Compensation			Lloyd's Syndicate			Corporate			Eliminations			Consolidated
	Net premiums earned	$	398,528		$	—		$	—		$	—		$	—		$	398,528
	Net investment income	—			—			—			99,282			—			99,282
	Equity in earnings (loss) of unconsolidated subsidiaries	—			—			—			(3,500		)	—			(3,500		)
	Net realized gains (losses)	—			—			—			47,650			—			47,650
	Other income	3,902			—			—			1,410			(7		)	5,305
	Gain on acquisition	—			—			—			35,986			—			35,986
	Net losses and loss adjustment expenses	(189,872		)	—			—			—			—			(189,872		)
	Underwriting, policy acquisition and operating expenses	(95,907		)	—			—			(9,692		)	7			(105,592		)
	Interest expense	—			—			—			(1,085		)	—			(1,085		)
	Income tax expense (benefit)	—			—			—			(60,044		)	—			(60,044		)
	Segment operating results	$	116,651		$	—		$	—		$	110,007		$	—		$	226,658
	Significant non-cash items
	Depreciation and amortization	$	4,845		$	—		$	—		$	29,519		$	—		$	34,364
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 United States.
		Three Months Ended September 30						Nine Months Ended September 30
	(In thousands)	2014			2013			2014			2013
	Specialty P&C Segment
	Gross premiums earned:
	Healthcare professional liability	$	120,623		$	128,532		$	361,179		$	382,678
	Legal professional liability	7,145			6,849			21,147			20,328
	Medical technology and life sciences products liability	9,258			8,436			27,043			24,442
	Other	420			463			1,445			1,336
	Ceded premiums earned*	(13,655		)	(10,682		)	(36,110		)	(30,256		)
	Segment net premiums earned	$	123,791		$	133,598		$	374,704		$	398,528
	Workers' Compensation Segment
	Gross premiums earned:
	Traditional business	$	42,345		$	—		$	119,702		$	—
	Alternative market business	14,345			—			40,253			—
	Ceded premiums earned	(6,898		)	—			(15,995		)	—
	Segment net premiums earned	$	49,792		$	—		$	143,960		$	—
	Lloyd's Syndicate Segment
	Gross premiums earned:
	Property and casualty*	$	4,085		$	—		$	7,110		$	—
	Ceded premiums earned	(640		)	—			(713		)	—
	Segment net premiums earned	$	3,445		$	—		$	6,397		$	—
	Consolidated net premiums earned	$	177,028		$	133,598		$	525,061		$	398,528
	* Includes premium ceded from the Specialty P&C Segment to the Lloyd's Syndicate Segment of $1.1 million for the three months and $1.6 million for nine months ended September 30, 2014, respectively.

Basis_of_Presentation_Details_

Basis of Presentation (Details Textual) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
			Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'	'	'	'	'
Number of reportable segments	'	'	4	'	'
Finite-lived intangible assets, net	$77.50	'	$77.50	'	$35.20
Indefinite-lived intangible assets, excluding goodwill	25.8	'	25.8	'	16.8
Amortization expense	2.6	1.3	7.7	4	'
Amortization expense in 2014	2.6	'	2.6	'	'
Amortization expense in 2015	8.3	'	8.3	'	'
Amortization expense in 2016	8	'	8	'	'
Amortization expense in 2017	5.7	'	5.7	'	'
Amortization expense in 2018	5.3	'	5.3	'	'
Deposit with an intermediate third-party	'	'	'	'	205
Segregated portfolio cell dividends payable	16.5	'	16.5	'	'
Earned but unbilled premiums	3.4	'	3.4	'	'
Reclassifications [Member]	'	'	'	'	'
Reclassifications [Line Items]	'	'	'	'	'
Unearned ceding commission	'	'	'	'	0.8
Ceding commission income	'	$1.50	'	$4.20	'

Business_Combinations_Details

Business Combinations (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Jan. 01, 2014	Jan. 01, 2014
						Eastern Insurance Holdings [Member]	Eastern Insurance Holdings [Member]
Business Acquisition [Line Items]	'	'	'	'	'	'	'
Fixed maturities, available for sale	'	'	'	'	'	'	$107,131
Equity securities, trading	'	'	'	'	'	'	65,945
Cash and short-term investments	'	'	'	'	'	'	58,944
Other investments	'	'	'	'	'	'	42,133
Premiums receivable	'	'	'	'	'	'	71,989
Receivable from reinsurers on paid and unpaid losses and LAE	'	'	'	'	'	'	18,942
Intangible assets	'	'	'	'	'	'	59,000
Deferred policy acquisition costs (see discussion below)	'	'	'	'	'	'	10,593
Other assets	'	'	'	'	'	'	19,225
Reserve for losses and loss adjustment expenses	'	'	'	'	'	'	-153,191
Unearned premiums	'	'	'	'	'	'	-80,268
Ceded balances payable	'	'	'	'	'	'	-9,507
Segregated portfolio cells dividends payable	'	'	'	'	'	'	-14,430
Deferred tax liabilities, net	'	'	'	'	'	'	-12,835
Other liabilities	'	'	'	'	'	'	-28,038
Fair value of net assets acquired	'	'	'	'	'	'	155,633
Goodwill	210,725	'	210,725	'	161,115	'	49,610
Total purchase consideration	'	'	'	'	'	205,243	'
ProAssurance Consolidated results	'	'	'	'	'	'	'
ProAssurance Pro Forma Consolidated Results, Revenue	203,833	229,608	634,330	686,391	'	'	'
ProAssurance Pro Forma Consolidated Results, Net Income	34,759	66,868	132,451	233,666	'	'	'
ProAssurance Actual Consolidated Results, Revenue	203,833	181,486	634,330	547,265	'	'	'
ProAssurance Actual Consolidated Results, Net Income	$34,778	$63,357	$131,451	$226,658	'	'	'

Business_Combinations_Details_

Business Combinations (Details 1) (Eastern Insurance Holdings [Member], USD $)	0 Months Ended
In Millions, unless otherwise specified	Jan. 01, 2014
Acquired Finite-Lived Intangible Assets [Line Items]	'
Estimated Fair Value on Acquisition Date	$50
Estimated Useful Life, Weighted Average Useful Life	'13 years	[1]
Agency relationships [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Estimated Fair Value on Acquisition Date	27
Estimated Useful Life	'15 years
Policyholder relationships [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Estimated Fair Value on Acquisition Date	8
Estimated Useful Life	'15 years
Trade names [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Estimated Fair Value on Acquisition Date	8
Estimated Useful Life	'15 years
Noncompete agreements [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Estimated Fair Value on Acquisition Date	$7
Estimated Useful Life	'3 years
[1]	Reflects the weighted average estimated useful life of acquired intangible assets that are subject to amortization.

Business_Combinations_Details_1

Business Combinations (Details 2) (Eastern Insurance Holdings [Member], Insurance license agreements [Member], USD $)	0 Months Ended
In Millions, unless otherwise specified	Jan. 01, 2014
Eastern Insurance Holdings [Member] | Insurance license agreements [Member]	'
Acquired Indefinite-lived Intangible Assets [Line Items]	'
Estimated Fair Value on Acquisition Date	$9

Business_Combinations_Details_2

Business Combinations (Details Textual) (USD $)	0 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Jan. 01, 2014	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013	Jan. 01, 2014
Business Acquisition [Line Items]	'	'	'	'	'
Goodwill	'	$210,725,000	$210,725,000	$161,115,000	'
Eastern Insurance Holdings [Member]	'	'	'	'	'
Business Acquisition [Line Items]	'	'	'	'	'
Voting interests acquired	'	'	'	'	100.00%
Business acquisition cash paid	205,243,000	'	'	'	'
Expenses related to the purchase of business	'	'	2,100,000	900,000	'
Goodwill	'	'	'	'	49,610,000
Risk premium used in determining underlying net cash flows for fair value of acquired assets/liabilities	'	'	'	'	9,300,000
Amortization period of fair value estimate of Acquired Reserves for Losses and related reinsurance recoverables	'6 years	'	'	'	'
Revenue since acquisition date	'	49,600,000	149,900,000	'	'
Earnings since acquisition date	'	$1,700,000	$7,100,000	'	'

Fair_Value_Measurement_Details

Fair Value Measurement (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:	'	'
Equity securities	$306,631	$253,541
Level 3 [Member] | State and municipal bonds [Member]	'	'
Financial instruments carried at fair value, classified as a part of:	'	'
Total assets	5,600	7,300
Level 3 [Member] | Other asset-backed securities [Member]	'	'
Financial instruments carried at fair value, classified as a part of:	'	'
Total assets	4,800	6,800
Fair Value, Measurements, Recurring [Member]	'	'
Financial instruments carried at fair value, classified as a part of:	'	'
Investment in unconsolidated subsidiaries	110,793	72,062
Other Investments	30,058	'
Total assets	3,789,275	3,692,257
Fair Value, Measurements, Recurring [Member] | U.S. Treasury obligations [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	176,813	170,714
Fair Value, Measurements, Recurring [Member] | U.S. Government-sponsored enterprise obligations [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	43,966	32,768
Fair Value, Measurements, Recurring [Member] | State and municipal bonds [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	1,087,634	1,154,666
Fair Value, Measurements, Recurring [Member] | Corporate debt, multiple observable inputs [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	1,459,550	1,346,977
Fair Value, Measurements, Recurring [Member] | Other corporate debt, NRSRO ratings available [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	10,793	11,449
Fair Value, Measurements, Recurring [Member] | Other corporate debt, NRSRO ratings not available [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	2,642	2,727
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	290,314	235,614
Fair Value, Measurements, Recurring [Member] | Agency commercial mortgage-backed securities [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	16,893	27,475
Fair Value, Measurements, Recurring [Member] | Other commercial mortgage-backed securities [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	57,323	61,390
Fair Value, Measurements, Recurring [Member] | Other asset-backed securities [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	100,892	74,269
Fair Value, Measurements, Recurring [Member] | Financial [Member]	'	'
Assets:	'	'
Equity securities	75,141	81,536
Fair Value, Measurements, Recurring [Member] | Utilities/Energy [Member]	'	'
Assets:	'	'
Equity securities	26,551	32,350
Fair Value, Measurements, Recurring [Member] | Consumer oriented [Member]	'	'
Assets:	'	'
Equity securities	64,912	66,461
Fair Value, Measurements, Recurring [Member] | Industrial [Member]	'	'
Assets:	'	'
Equity securities	54,912	57,262
Fair Value, Measurements, Recurring [Member] | Bond funds [Member]	'	'
Assets:	'	'
Equity securities	53,178	'
Fair Value, Measurements, Recurring [Member] | All other [Member]	'	'
Assets:	'	'
Equity securities	31,937	15,932
Fair Value, Measurements, Recurring [Member] | Short-term Investments [Member]	'	'
Assets:	'	'
Short-term investments	94,973	248,605
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]	'	'
Financial instruments carried at fair value, classified as a part of:	'	'
Investment in unconsolidated subsidiaries	0	0
Other Investments	4,830	'
Total assets	405,784	502,146
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	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other corporate debt, NRSRO ratings available [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other corporate debt, NRSRO ratings not available [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	75,141	81,536
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Utilities/Energy [Member]	'	'
Assets:	'	'
Equity securities	26,551	32,350
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Consumer oriented [Member]	'	'
Assets:	'	'
Equity securities	64,912	66,461
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Industrial [Member]	'	'
Assets:	'	'
Equity securities	54,912	57,262
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Bond funds [Member]	'	'
Assets:	'	'
Equity securities	53,178	'
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | All other [Member]	'	'
Assets:	'	'
Equity securities	31,937	15,932
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Short-term Investments [Member]	'	'
Assets:	'	'
Short-term investments	94,323	248,605
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]	'	'
Financial instruments carried at fair value, classified as a part of:	'	'
Investment in unconsolidated subsidiaries	0	0
Other Investments	25,228	'
Total assets	3,248,896	3,089,721
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Treasury obligations [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	176,813	170,714
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Government-sponsored enterprise obligations [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	43,966	32,768
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | State and municipal bonds [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	1,082,040	1,147,328
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate debt, multiple observable inputs [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	1,459,550	1,346,977
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other corporate debt, NRSRO ratings available [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other corporate debt, NRSRO ratings not available [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	290,314	235,614
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Agency commercial mortgage-backed securities [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	16,893	27,475
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other commercial mortgage-backed securities [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	57,323	61,390
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other asset-backed securities [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	96,119	67,455
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	'
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | All other [Member]	'	'
Assets:	'	'
Equity securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Short-term Investments [Member]	'	'
Assets:	'	'
Short-term investments	650	'
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]	'	'
Financial instruments carried at fair value, classified as a part of:	'	'
Investment in unconsolidated subsidiaries	110,793	72,062
Other Investments	0	'
Total assets	134,595	100,390
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	5,594	7,338
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] | Other corporate debt, NRSRO ratings available [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	10,793	11,449
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other corporate debt, NRSRO ratings not available [Member]	'	'
Assets:	'	'
Fixed maturities, available for sale	2,642	2,727
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	4,773	6,814
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	'
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	'

Fair_Value_Measurement_Details1

Fair Value Measurement (Details 1) (USD $)	Sep. 30, 2014		Dec. 31, 2013
Secured debt fund [Member]	'		'
Investments in private funds [Abstract]	'		'
Investments LPs/LLCs unfunded commitments	$16,200,000	[1]	'
Investments in LPs/LLCs fair value	23,896,000	[1]	13,233,000	[1]
Long equity fund [Member]	'		'
Investments in private funds [Abstract]	'		'
Investments LPs/LLCs unfunded commitments	0	[2]	'
Investments in LPs/LLCs fair value	7,034,000	[2]	6,574,000	[2]
Long/Short equity funds [Member]	'		'
Investments in private funds [Abstract]	'		'
Investments LPs/LLCs unfunded commitments	0	[3]	'
Investments in LPs/LLCs fair value	25,016,000	[3]	28,385,000	[3]
Non-public equity funds [Member]	'		'
Investments in private funds [Abstract]	'		'
Investments LPs/LLCs unfunded commitments	71,518,000	[4]	'
Investments in LPs/LLCs fair value	42,818,000	[4]	23,870,000	[4]
Multi-Strategy Fund of Funds [Member]	'		'
Investments in private funds [Abstract]	'		'
Investments LPs/LLCs unfunded commitments	0	[5]	'
Investments in LPs/LLCs fair value	8,263,000	[5]	0	[5]
Structured Credit Fund [Member]	'		'
Investments in private funds [Abstract]	'		'
Investments LPs/LLCs unfunded commitments	0	[6]	'
Investments in LPs/LLCs fair value	3,766,000	[6]	0	[6]
Investment in LPs/LLCs [Member]	'		'
Investments in private funds [Abstract]	'		'
Investments in LPs/LLCs fair value	$110,793,000		$72,062,000
[1]	The LP is structured to provide income and capital appreciation primarily through investments in senior secured debt. Redemptions are not allowed. Income and capital are to be periodically distributed at the discretion of the LP over an anticipated time frame that spans from 7 to 9 years.
[2]	The LP 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]	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 event-driven market opportunities. The funds generally permit quarterly or semi-annual redemptions of the investors’ existing capital balance with 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]	Comprised of interests in three 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 LPs. One LP allows redemption by special consent; 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 from 4 to 12 years.
[5]	The LLC is 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 the LLC Board is permitted discretion to periodically extend offers to repurchase units of the LLC.
[6]	The LP seeks 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.

Fair_Value_Measurement_Details2

Fair Value Measurement (Details 2) (Level 3 [Member], USD $)

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

In Thousands, unless otherwise specified

State and municipal bonds [Member]

State and municipal bonds [Member]

State and municipal bonds [Member]

State and municipal bonds [Member]

State and municipal bonds [Member]

State and municipal bonds [Member]

State and municipal bonds [Member]

State and municipal bonds [Member]

Corporate debt with limited observable inputs [Member]

Corporate debt with limited observable inputs [Member]

Corporate debt with limited observable inputs [Member]

Corporate debt with limited observable inputs [Member]

Corporate debt with limited observable inputs [Member]

Corporate debt with limited observable inputs [Member]

Corporate debt with limited observable inputs [Member]

Corporate debt with limited observable inputs [Member]

Other asset-backed securities [Member]

Other asset-backed securities [Member]

Other asset-backed securities [Member]

Other asset-backed securities [Member]

Other asset-backed securities [Member]

Other asset-backed securities [Member]

Other asset-backed securities [Member]

Other asset-backed securities [Member]

Market comparable securities valuation technique [Member]

Market comparable securities valuation technique [Member]

Market comparable securities valuation technique [Member]

Discount cash flows valuation technique [Member]

Discount cash flows valuation technique [Member]

Discount cash flows valuation technique [Member]

Market comparable securities valuation technique [Member]

Market comparable securities valuation technique [Member]

Market comparable securities valuation technique [Member]

Discount cash flows valuation technique [Member]

Discount cash flows valuation technique [Member]

Discount cash flows valuation technique [Member]

Market comparable securities valuation technique [Member]

Market comparable securities valuation technique [Member]

Market comparable securities valuation technique [Member]

Discount cash flows valuation technique [Member]

Discount cash flows valuation technique [Member]

Discount cash flows valuation technique [Member]

Minimum [Member]

Maximum [Member]

Weighted Average [Member]

Minimum [Member]

Maximum [Member]

Weighted Average [Member]

Minimum [Member]

Maximum [Member]

Weighted Average [Member]

Minimum [Member]

Maximum [Member]

Weighted Average [Member]

Minimum [Member]

Maximum [Member]

Weighted Average [Member]

Minimum [Member]

Maximum [Member]

Weighted Average [Member]

Assets:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Assets, Fair Value

$5,600

$7,300

'

'

'

'

'

'

$13,400

$14,200

'

'

'

'

'

'

$4,800

$6,800

'

'

'

'

'

'

Comparability Adjustment

'

'

0.00%

10.00%

5.00%

0.00%

10.00%

5.00%

'

'

0.00%

5.00%

2.50%

0.00%

5.00%

2.50%

'

'

0.00%

5.00%

2.50%

0.00%

5.00%

2.50%

Fair_Value_Measurement_Details3

Fair Value Measurement (Details 3) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:	'	'	'	'
Beginning Balance	$128,994	$65,612	$100,390	$60,140
Included in earnings, as a part of:	'	'	'	'
Included in other comprehensive income	-47	-205	732	-595
Purchases	11,556	2,354	45,631	29,801
Sales	-4,056	-4,051	-7,373	-17,132
Transfers in	0	100	2,424	1,801
Transfers out	-1,181	0	-12,568	-12,254
Ending Balance	134,595	65,110	134,595	65,110
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	-683	1,301	5,413	3,582
U.S. Government-sponsored enterprise obligations [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:	'	'	'	'
Beginning Balance	0	0	0	0
Included in earnings, as a part of:	'	'	'	'
Included in other comprehensive income	0	0	1	0
Purchases	0	0	1,000	0
Sales	0	0	0	0
Transfers in	0	0	0	0
Transfers out	0	0	-1,001	0
Ending Balance	0	0	0	0
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0	0	0
State and municipal bonds [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:	'	'	'	'
Beginning Balance	7,148	5,025	7,338	7,175
Included in earnings, as a part of:	'	'	'	'
Included in other comprehensive income	-76	0	-34	0
Purchases	0	0	1,861	0
Sales	-1,474	0	-1,731	-2,106
Transfers in	0	0	2,119	0
Transfers out	0	0	-3,854	0
Ending Balance	5,594	5,025	5,594	5,025
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0	0	0
Corporate debt [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:	'	'	'	'
Beginning Balance	14,544	11,359	14,176	15,191
Included in earnings, as a part of:	'	'	'	'
Included in other comprehensive income	35	-221	702	-514
Purchases	-499	0	2,000	7,470
Sales	-661	-503	-1,469	-1,368
Transfers in	0	100	0	100
Transfers out	'	0	-2,025	-9,973
Ending Balance	13,435	10,734	13,435	10,734
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0	0	0
Asset-backed securities [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:	'	'	'	'
Beginning Balance	5,960	4,679	6,814	4,035
Included in earnings, as a part of:	'	'	'	'
Included in other comprehensive income	-6	16	63	-81
Purchases	0	0	3,340	1,356
Sales	0	0	-61	-18
Transfers in	0	0	305	1,701
Transfers out	-1,181	0	-5,688	-2,281
Ending Balance	4,773	4,695	4,773	4,695
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0	0	0
Investment in LPs/LLCs [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:	'	'	'	'
Beginning Balance	101,342	44,549	72,062	33,739
Included in earnings, as a part of:	'	'	'	'
Included in other comprehensive income	0	0	0	0
Purchases	12,055	2,354	37,430	20,975
Sales	-1,921	-3,548	-4,112	-13,640
Transfers in	0	0	0	0
Transfers out	0	0	0	0
Ending Balance	110,793	44,656	110,793	44,656
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	-683	1,301	5,413	3,582
Net investment Income [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	12	-1	38	-120
Net investment Income [Member] | U.S. Government-sponsored enterprise obligations [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	0	0
Net investment Income [Member] | State and municipal bonds [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	-4	0	-10	0
Net investment Income [Member] | Corporate debt [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	16	-1	48	-103
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	0	-17
Net investment Income [Member] | Investment in LPs/LLCs [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	0	0
Equity in earnings (loss) of unconsolidated subsidiaries [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	-683	1,301	5,413	3,582
Equity in earnings (loss) of unconsolidated subsidiaries [Member] | U.S. Government-sponsored enterprise obligations [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	0	0
Equity in earnings (loss) of unconsolidated subsidiaries [Member] | State and municipal bonds [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	0	0
Equity in earnings (loss) of unconsolidated subsidiaries [Member] | Corporate debt [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	0	0
Equity in earnings (loss) of unconsolidated subsidiaries [Member] | Asset-backed securities [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	0	0
Equity in earnings (loss) of unconsolidated subsidiaries [Member] | Investment in LPs/LLCs [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	-683	1,301	5,413	3,582
Net realized investment gains (losses) [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	-92	-113
Net realized investment gains (losses) [Member] | U.S. Government-sponsored enterprise obligations [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	0	0
Net realized investment gains (losses) [Member] | State and municipal bonds [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	0	0	-95	-44
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	0	0	3	-69
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	0	0
Net realized investment gains (losses) [Member] | Investment in LPs/LLCs [Member]	'	'	'	'
Included in earnings, as a part of:	'	'	'	'
Total gains (losses) realized and unrealized, included in earnings	$0	$0	$0	$0

Fair_Value_Measurement_Details4

Fair Value Measurement (Details 4) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial assets:	'	'
BOLI	$55,918	$54,374
Other investments	92,010	52,240
Other assets	100,957	329,979
Financial liabilities:	'	'
Senior notes due 2023	250,000	250,000
Other Liabilities	164,095	143,079
Not Measured At Fair Value [Member] | Carrying Value [Member]	'	'
Financial assets:	'	'
BOLI	55,918	54,374
Other investments	61,952	52,240
Other assets	21,298	17,940
Financial liabilities:	'	'
Other Liabilities	14,022	13,303
Not Measured At Fair Value [Member] | Carrying Value [Member] | Senior notes due 2023 [Member]	'	'
Financial liabilities:	'	'
Senior notes due 2023	250,000	250,000
Not Measured At Fair Value [Member] | Level 3 [Member] | Fair Value [Member]	'	'
Financial assets:	'	'
BOLI	55,918	54,374
Other investments	63,247	51,833
Other assets	21,248	17,940
Financial liabilities:	'	'
Other Liabilities	14,139	13,303
Not Measured At Fair Value [Member] | Level 3 [Member] | Fair Value [Member] | Senior notes due 2023 [Member]	'	'
Financial liabilities:	'	'
Senior notes due 2023	$273,750	$262,500

Fair_Value_Measurement_Details5

Fair Value Measurement (Details Textuals) (Details)	9 Months Ended
	Sep. 30, 2014
Long equity fund [Member]	'
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]	'
Investment redemption notice period	'15 days
Structured Credit Fund [Member]	'
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]	'
Investment redemption notice period	'90 days
Minimum [Member] | Secured debt fund [Member]	'
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]	'
Liquidating investments remaining period	'7 years
Minimum [Member] | Long/Short Equity Funds [Member]	'
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]	'
Redemption percentage of LP at NAV for which initial payment is limited	90.00%
Investment redemption notice period	'30 days
Minimum [Member] | Non-public equity funds [Member]	'
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]	'
Liquidating investments remaining period	'4 years
Maximum [Member] | Secured debt fund [Member]	'
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]	'
Liquidating investments remaining period	'9 years
Maximum [Member] | Long equity fund [Member]	'
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]	'
Payment period for redemption of LP valued at NAV	'10 days
Maximum [Member] | 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
Investment redemption notice period	'90 days
Maximum [Member] | Non-public equity funds [Member]	'
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]	'
Liquidating investments remaining period	'12 years

Fair_Value_Measurement_Details6

Fair Value Measurement (Details Textuals 1) (Details) (USD $)	Sep. 30, 2014	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'	'
Fair value level 1 to level 2 transfers	$0	$0
Fair value level 2 to level 1 transfers	$0	$0

Investments_Details

Investments (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
U.S. Treasury obligations [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	$173,632	$166,115
Gross Unrealized Gains	4,396	6,118
Gross Unrealized Losses	1,215	1,519
Estimated Fair Value	176,813	170,714
U.S. Government-sponsored enterprise obligations [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	42,480	30,942
Gross Unrealized Gains	1,709	2,251
Gross Unrealized Losses	223	425
Estimated Fair Value	43,966	32,768
State and municipal bonds [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	1,038,278	1,116,060
Gross Unrealized Gains	50,055	46,533
Gross Unrealized Losses	699	7,927
Estimated Fair Value	1,087,634	1,154,666
Corporate debt [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	1,433,266	1,321,838
Gross Unrealized Gains	48,894	53,059
Gross Unrealized Losses	9,175	13,744
Estimated Fair Value	1,472,985	1,361,153
Residential mortgage-backed securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	282,717	230,861
Gross Unrealized Gains	8,817	7,608
Gross Unrealized Losses	1,220	2,855
Estimated Fair Value	290,314	235,614
Agency commercial mortgage-backed securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	16,785	27,268
Gross Unrealized Gains	172	343
Gross Unrealized Losses	64	136
Estimated Fair Value	16,893	27,475
Other commercial mortgage-backed securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	55,853	59,066
Gross Unrealized Gains	1,587	2,491
Gross Unrealized Losses	117	167
Estimated Fair Value	57,323	61,390
Other asset-backed securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	100,715	74,106
Gross Unrealized Gains	346	487
Gross Unrealized Losses	169	324
Estimated Fair Value	100,892	74,269
Debt Securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	3,143,726	3,026,256
Gross Unrealized Gains	115,976	118,890
Gross Unrealized Losses	12,882	27,097
Estimated Fair Value	$3,246,820	$3,118,049

Investments_Details_1

Investments (Details 1) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
U.S. Treasury obligations [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	$173,632	$166,115
Due in one year or less	19,612	'
Due after one year through five years	104,211	'
Due after five years through ten years	48,950	'
Due after ten years	4,040	'
Estimated Fair Value	176,813	170,714
U.S. Government-sponsored enterprise obligations [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	42,480	30,942
Due in one year or less	8,002	'
Due after one year through five years	25,465	'
Due after five years through ten years	10,160	'
Due after ten years	339	'
Estimated Fair Value	43,966	32,768
State and municipal bonds [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	1,038,278	1,116,060
Due in one year or less	49,169	'
Due after one year through five years	393,569	'
Due after five years through ten years	442,212	'
Due after ten years	202,684	'
Estimated Fair Value	1,087,634	1,154,666
Corporate debt [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	1,433,266	1,321,838
Due in one year or less	157,683	'
Due after one year through five years	694,254	'
Due after five years through ten years	598,183	'
Due after ten years	22,865	'
Estimated Fair Value	1,472,985	1,361,153
Residential mortgage-backed securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	282,717	230,861
Estimated Fair Value	290,314	235,614
Agency commercial mortgage-backed securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	16,785	27,268
Estimated Fair Value	16,893	27,475
Other commercial mortgage-backed securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	55,853	59,066
Estimated Fair Value	57,323	61,390
Other asset-backed securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	100,715	74,106
Estimated Fair Value	100,892	74,269
Debt Securities [Member]	'	'
Fixed maturities, available for sale	'	'
Amortized Cost	3,143,726	3,026,256
Estimated Fair Value	$3,246,820	$3,118,049

Investments_Details_2

Investments (Details 2) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Other Investments	'	'
Other investments	$92,010	$52,240
Investments in LPs/LLCs, at cost [Member]	'	'
Other Investments	'	'
Other investments	57,607	47,258
Convertible securities, at fair value [Member]	'	'
Other Investments	'	'
Other investments	30,058	0
Other, principally FHLB capital stock at cost [Member]	'	'
Other Investments	'	'
Other investments	$4,345	$4,982

Investments_Details_3

Investments (Details 3) (USD $)	9 Months Ended
	Sep. 30, 2014		Dec. 31, 2013
Unconsolidated Subsidiaries	'		'
Investment in unconsolidated subsidiaries	$254,962,000		$214,236,000
Tax credit partnerships [Member]	'		'
Unconsolidated Subsidiaries	'		'
Unfunded Commitments	15,710,000	[1]	'
Investment in unconsolidated subsidiaries	137,386,000		142,174,000
Secured debt fund [Member]	'		'
Unconsolidated Subsidiaries	'		'
Unfunded Commitments	16,200,000	[1]	'
Investment in unconsolidated subsidiaries	23,896,000		13,233,000
Secured debt fund [Member] | Maximum [Member]	'		'
Unconsolidated Subsidiaries	'		'
Percentage Ownership	20.00%		'
Long equity fund [Member]	'		'
Unconsolidated Subsidiaries	'		'
Unfunded Commitments	0	[1]	'
Investment in unconsolidated subsidiaries	7,034,000		6,574,000
Long equity fund [Member] | Maximum [Member]	'		'
Unconsolidated Subsidiaries	'		'
Percentage Ownership	20.00%		'
Long/Short equity funds [Member]	'		'
Unconsolidated Subsidiaries	'		'
Unfunded Commitments	0	[1]	'
Investment in unconsolidated subsidiaries	25,016,000		28,385,000
Long/Short equity funds [Member] | Maximum [Member]	'		'
Unconsolidated Subsidiaries	'		'
Percentage Ownership	25.00%		'
Non-public equity funds [Member]	'		'
Unconsolidated Subsidiaries	'		'
Unfunded Commitments	88,034,000	[1]	'
Investment in unconsolidated subsidiaries	46,127,000		23,870,000
Non-public equity funds [Member] | Maximum [Member]	'		'
Unconsolidated Subsidiaries	'		'
Percentage Ownership	20.00%		'
Multi-Strategy Fund of Funds [Member]	'		'
Unconsolidated Subsidiaries	'		'
Unfunded Commitments	0	[1]	'
Investment in unconsolidated subsidiaries	8,263,000		0
Multi-Strategy Fund of Funds [Member] | Maximum [Member]	'		'
Unconsolidated Subsidiaries	'		'
Percentage Ownership	20.00%		'
Structured Credit Fund [Member]	'		'
Unconsolidated Subsidiaries	'		'
Unfunded Commitments	0	[1]	'
Investment in unconsolidated subsidiaries	3,766,000		0
Structured Credit Fund [Member] | Maximum [Member]	'		'
Unconsolidated Subsidiaries	'		'
Percentage Ownership	20.00%		'
Real Estate Funds [Member]	'		'
Unconsolidated Subsidiaries	'		'
Unfunded Commitments	6,526,000	[1]	'
Investment in unconsolidated subsidiaries	$3,474,000		$0
Real Estate Funds [Member] | Maximum [Member]	'		'
Unconsolidated Subsidiaries	'		'
Percentage Ownership	20.00%		'
[1]	Unfunded commitments are included in the carrying value of tax credit partnerships only.

Investments_Details_4

Investments (Details 4) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments in LPs/LLCs [Member]	'	'
Investments held in an unrealized loss position	'	'
Other Investments, Investments in LPs/LLCs carried at cost, Fair Value	$17,106	$14,752
Other Investments, Investments in LPs/LLCs carried at cost, Unrealized Loss	582	1,059
Other investments, Investments in LPs/LLCs carried at cost, Less than Twelve Months, Fair Value	15,458	13,166
Other Investments, Investments in LPs/LLCs carried at cost, Less than 12 Months, Unrealized Losses	577	1,018
Other Investments, Investments in LPs/LLCs carried at cost, Twelve Months or Longer, Fair Value	1,648	1,586
Other Investments, Investments in LPs/LLCs carried at cost, 12 Months or Longer, Unrealized Losses	5	41
U.S. Treasury obligations [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	59,770	47,668
Unrealized Loss	1,215	1,519
Less than 12 months, Fair Value	37,309	44,304
Less than 12 months, Unrealized Loss	534	1,182
More than 12 months, Fair Value	22,461	3,364
More than 12 months, Unrealized Loss	681	337
US Government-sponsored Enterprises Debt Securities [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	7,887	6,640
Unrealized Loss	223	425
Less than 12 months, Fair Value	2,136	5,752
Less than 12 months, Unrealized Loss	22	321
More than 12 months, Fair Value	5,751	888
More than 12 months, Unrealized Loss	201	104
State and municipal bonds [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	71,155	203,970
Unrealized Loss	699	7,927
Less than 12 months, Fair Value	32,129	184,401
Less than 12 months, Unrealized Loss	128	6,640
More than 12 months, Fair Value	39,026	19,569
More than 12 months, Unrealized Loss	571	1,287
Corporate debt [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	477,806	349,277
Unrealized Loss	9,175	13,744
Less than 12 months, Fair Value	372,670	324,510
Less than 12 months, Unrealized Loss	5,909	12,061
More than 12 months, Fair Value	105,136	24,767
More than 12 months, Unrealized Loss	3,266	1,683
Residential mortgage-backed securities [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	66,143	93,608
Unrealized Loss	1,220	2,855
Less than 12 months, Fair Value	26,012	84,045
Less than 12 months, Unrealized Loss	105	2,393
More than 12 months, Fair Value	40,131	9,563
More than 12 months, Unrealized Loss	1,115	462
Agency commercial mortgage-backed securities [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	10,432	11,658
Unrealized Loss	64	136
Less than 12 months, Fair Value	8,536	11,082
Less than 12 months, Unrealized Loss	8	116
More than 12 months, Fair Value	1,896	576
More than 12 months, Unrealized Loss	56	20
Other commercial mortgage-backed securities [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	14,592	11,153
Unrealized Loss	117	167
Less than 12 months, Fair Value	7,528	10,215
Less than 12 months, Unrealized Loss	33	159
More than 12 months, Fair Value	7,064	938
More than 12 months, Unrealized Loss	84	8
Other asset-backed securities [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	39,328	25,539
Unrealized Loss	169	324
Less than 12 months, Fair Value	35,269	21,804
Less than 12 months, Unrealized Loss	77	77
More than 12 months, Fair Value	4,059	3,735
More than 12 months, Unrealized Loss	92	247
Debt Securities [Member]	'	'
Investments held in an unrealized loss position	'	'
Fair Value	747,113	749,513
Unrealized Loss	12,882	27,097
Less than 12 months, Fair Value	521,589	686,113
Less than 12 months, Unrealized Loss	6,816	22,949
More than 12 months, Fair Value	225,524	63,400
More than 12 months, Unrealized Loss	$6,066	$4,148

Investments_Details_5

Investments (Details 5) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net Investment Income	'	'	'	'
Investment fees and expenses	($1,712)	($1,810)	($6,360)	($5,427)
Net investment income	32,830	33,889	92,788	99,282
Fixed maturities [Member]	'	'	'	'
Net Investment Income	'	'	'	'
Investment Income	28,442	30,672	85,402	93,687
Equities [Member]	'	'	'	'
Net Investment Income	'	'	'	'
Investment Income	2,661	2,394	7,479	7,000
Short-term investments and Other invested assets [Member]	'	'	'	'
Net Investment Income	'	'	'	'
Investment Income	2,793	2,000	4,723	2,514
Business owned life insurance [Member]	'	'	'	'
Net Investment Income	'	'	'	'
Investment Income	$646	$633	$1,544	$1,508

Investments_Details_6

Investments (Details 6) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Gain (Loss) on Investments [Line Items]	'	'	'	'
Other-than-temporary impairment (OTTI) losses	($1,425)	$0	($1,475)	($71)
Portion of OTTI losses recognized in (reclassified from) other comprehensive income before taxes	268	0	268	0
Net impairments recognized in earnings	-1,157	0	-1,207	-71
Gross realized gains, available-for-sale securities	736	7,708	3,711	14,631
Gross realized (losses), available-for-sale securities	-52	-5,305	-371	-6,269
Net realized gains (losses), trading securities	3,227	5,818	21,830	14,650
Net realized gains (losses), Other investments	55	0	321	0
Change in unrealized holding gains (losses), trading securities	-10,402	3,355	-17,906	23,784
Change in unrealized holding gains (losses), convertible securities, carried at fair value	-538	0	1,281	0
Other	0	924	0	925
Total net realized investment gains (losses)	-8,131	12,500	7,659	47,650
US States and Political Subdivisions Debt Securities [Member]	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Other-than-temporary impairment (OTTI) losses	0	0	-50	-71
Corporate debt [Member]	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Other-than-temporary impairment (OTTI) losses	-1,425	0	-1,425	0
Portion of OTTI losses recognized in (reclassified from) other comprehensive income before taxes	$268	$0	$268	$0

Investments_Details_7

Investments (Details 7) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Cumulative credit losses recorded in earnings related to impaired debt securities	'	'	'	'
Accumulated credit losses related to impaired debt securities, Beginning Balance	$83	$413	$83	$3,301
No OTTI has been previously recognized	149	0	149	0
Reductions due to: Securities sold during the period (realized)	0	-330	0	-3,218
Accumulated credit losses related to impaired debt securities, Ending Balance	$232	$83	$232	$83

Investments_Details_8

Investments (Details 8) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Information regarding sales and purchases of available-for-sale securities	'	'	'	'
Proceeds from sales (exclusive of maturities and paydowns)	$24,800,000	$319,200,000	$147,300,000	$494,800,000
Purchases	$146,500,000	$98,800,000	$511,894,000	$406,152,000

Investments_Details_Textual

Investments (Details Textual) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
	Affiliate		Tax Credit Partnerships Almost 100% Ownership [Member]	Tax Credit Partnerships Less Than 20% Ownership [Member]	Maximum [Member]	Maximum [Member]	Maximum [Member]	Fixed maturities [Member]	Short-term Investments [Member]	Non Government-Backed [Member]	Non Government-Backed [Member]
			investment_interest			Tax Credit Partnerships Almost 100% Ownership [Member]	Tax Credit Partnerships Less Than 20% Ownership [Member]			Issuer	Security
										Security	Issuer
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Number of investment affiliates exceeding shareholder's equity ten percent threshold limit	0	'	'	'	'	'	'	'	'	'	'
Threshold limit of investments based on shareholders' equity	10.00%	'	'	'	'	'	'	'	'	'	'
Securities on deposit with state insurance departments	$48,200,000	'	'	'	'	'	'	'	'	'	'
Required FAL Deposit	77,200,000	'	'	'	'	'	'	71,500,000	5,700,000	'	'
Business owned life insurance cost	33,000,000	'	'	'	'	'	'	'	'	'	'
Period for federal home loan bank stock liquidation process	'	'	'	'	'5 years	'	'	'	'	'	'
Number of tax credit partnerships almost 100% ownership percentage	'	'	2	'	'	'	'	'	'	'	'
Percentage Ownership	'	'	'	'	'	100.00%	20.00%	'	'	'	'
Investment in unconsolidated subsidiaries	254,962,000	214,236,000	60,900,000	76,500,000	'	'	'	'	'	'	'
Number of debt securities in unrealized loss position	'	'	'	'	'	'	'	'	'	617	714
Debt securities in unrealized loss position as percentage of total debt securities held	'	'	'	'	'	'	'	'	'	21.10%	26.30%
Number of issuers in unrealized loss position	'	'	'	'	'	'	'	'	'	441	516
Single greatest unrealized loss position	'	'	'	'	'	'	'	'	'	500,000	400,000
Second greatest unrealized loss position	'	'	'	'	'	'	'	'	'	$300,000	$400,000

Income_Taxes_Details_Textual

Income Taxes (Details Textual) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Jan. 01, 2014
In Millions, unless otherwise specified			Eastern Insurance Holdings [Member]
Income Tax Contingency [Line Items]	'	'	'
Refund adjustment from settlement with taxing authority	$30.60	'	'
Unrecognized tax benefits	0.6	4.8	0.6
Income taxes receivable	$11.40	$27.30	'

Deferred_Policy_Acquisition_Co1

Deferred Policy Acquisition Costs (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Insurance [Abstract]	'	'	'	'
Amortization of deferred policy acquisition costs	$16.70	$13.90	$52.90	$39

Reserve_for_Losses_and_Loss_Ad1

Reserve for Losses and Loss Adjustment Expenses (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Summary of reserve for losses and loss adjustment expenses	'	'	'	'
Minimum period for claims resolution	'	'	'5 years	'
Net losses:	'	'	'	'
Favorable development of reserves established in prior years, net	$42.90	$49.40	$133.30	$141
Liability for unpaid claims and claims adjustment expense incurred claims prior years accident years	'2007 through 2012	'2005 through 2011	'2007 through 2012	'2005 through 2011
Eastern Insurance Holdings [Member]	'	'	'	'
Net losses:	'	'	'	'
Favorable development of reserves established in prior years, net	$0.60	'	$2.90	'

Commitments_and_Contingencies_

Commitments and Contingencies (Details Textual)	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014
	USD ($)	GBP (£)	Non-Public Investment Entities [Member]
			USD ($)
Other Commitment, Fiscal Year Maturity [Abstract]	'	'	'
Commitments Total	'	'	$164,700,000
Commitments due 2014	'	'	22,600,000
Commitments due 2015 and 2016	'	'	124,700,000
Commitments due 2017 and 2018	'	'	16,500,000
Commitments due thereafter	'	'	900,000
Required FAL Deposit	77,200,000	'	'
Estimated FAL For Next Underwriting Year	'	50,900,000	'
Estimated Additional Funding Required In Current Year For FAL	9,800,000	5,800,000	'
Current lending capacity under revolving credit agreement	16,000,000	10,000,000	'
Interest rate on revolving credit agreement	8.50%	8.50%	'
Advances outstanding under revolving credit agreement	$9,200,000	£ 5,500,000	'

Longterm_Debt_Details

Long-term Debt (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Outstanding long-term debt	'	'
Long-term debt	$250,000,000	$250,000,000
Senior Notes [Member] | Senior notes due 2023 [Member]	'	'
Outstanding long-term debt	'	'
Long-term debt	250,000,000	250,000,000
Interest rate on Senior Notes	5.30%	'
Line of Credit [Member] | Revolving Credit Agreement [Member]	'	'
Outstanding long-term debt	'	'
Long-term debt	0	0
Maximum outstanding borrowings under revolving credit agreement	$200,000,000	'

Shareholders_Equity_Details

Shareholders' Equity (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reclassification adjustments related to available-for-sale securities	'	'	'	'
Net realized investment gains (losses)	($8,131)	$12,500	$7,659	$47,650
Total amounts reclassified, before tax effect	47,303	86,673	174,779	286,702
Tax effect (at 35%)	-12,525	-23,316	-43,328	-60,044
Net income	34,778	63,357	131,451	226,658
Tax rate used to compute the tax effect of OCI components	35.00%	35.00%	35.00%	35.00%
Deferred tax expense (benefit) included in OCI	-5,126	-1,746	-2,571	-26,358
Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'	'
Reclassification adjustments related to available-for-sale securities	'	'	'	'
Total amounts reclassified, before tax effect	-473	2,403	2,133	8,291
Tax effect (at 35%)	166	-841	-747	-2,902
Net income	-307	1,562	1,386	5,389
Reclassification out of Accumulated Other Comprehensive Income [Member] | Realized investment gains (losses) [Member]	'	'	'	'
Reclassification adjustments related to available-for-sale securities	'	'	'	'
Net realized investment gains (losses)	-473	2,403	2,133	8,638
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	'	'	'	'
Reclassification adjustments related to available-for-sale securities	'	'	'	'
Net realized investment gains (losses)	$0	$0	$0	($347)

Shareholders_Equity_Details_Te

Shareholders' Equity (Details Textual) (USD $)	1 Months Ended	3 Months Ended						9 Months Ended
	Feb. 28, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'
Authorized common stock (in shares)	'	100,000,000	'	'	'	'	'	100,000,000	'	100,000,000
Authorized preferred stock (in shares)	'	50,000,000	'	'	'	'	'	50,000,000	'	50,000,000
Quarterly dividend declared, per share (USD per share)	'	$0.30	$0.30	$0.30	$0.25	$0.25	$0.25	$0.90	$0.75	'
Dividend declared	'	$17,300,000	'	'	$15,500,000	'	'	$52,900,000	$46,400,000	'
Total authorizations which remain available for use	'	136,700,000	'	'	'	'	'	136,700,000	'	'
Common shares acquired (in shares)	'	'	'	'	'	'	'	3,700,000	200,000	'
Cost of common shares reacquired	'	'	'	'	'	'	'	167,242,000	7,964,000	'
Share-based compensation	'	2,400,000	'	'	2,200,000	'	'	8,022,000	6,930,000	'
Tax benefits from share-based compensation expense	'	800,000	'	'	800,000	'	'	2,800,000	2,400,000	'
Bonus compensation shares issued (in shares)	30,000	'	'	'	'	'	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities	'	$800,000	'	'	'	'	'	$800,000	'	$500,000
Tax rate used to compute the tax effect of amounts reclassified out of OCI	'	35.00%	'	'	35.00%	'	'	35.00%	35.00%	'
Restricted Share Units [Member]	'	'	'	'	'	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'
Awards in period (in shares)	50,000	'	'	'	'	'	'	'	'	'
Fair value of each unit awarded (USD per share)	46.34	'	'	'	'	'	'	'	'	'
Award vesting period	'3 years	'	'	'	'	'	'	'	'	'
Shares issued in period for share-based compensation (in shares)	29,000	'	'	'	'	'	'	'	'	'
Performance Shares [Member]	'	'	'	'	'	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'
Awards in period (in shares)	161,000	'	'	'	'	'	'	'	'	'
Fair value of each unit awarded (USD per share)	46.34	'	'	'	'	'	'	'	'	'
Award vesting period	'3 years	'	'	'	'	'	'	'	'	'
Shares issued in period for share-based compensation (in shares)	111,000	'	'	'	'	'	'	'	'	'
Award payout rate	125.00%	'	'	'	'	'	'	'	'	'
Minimum [Member] | Performance Shares [Member]	'	'	'	'	'	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'
Award payout rate	75.00%	'	'	'	'	'	'	'	'	'
Maximum [Member] | Performance Shares [Member]	'	'	'	'	'	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'
Award payout rate	125.00%	'	'	'	'	'	'	'	'	'

Variable_Interest_Entities_Det

Variable Interest Entities (Details) (Variable Interest Entity, Not Primary Beneficiary [Member], USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Other Investments [Member]	'	'
Variable Interest Entity [Line Items]	'	'
VIE interests carrying value	$37.60	$27.30
VIE interest maximum loss exposure	37.6	'
Investment in unconsolidated subsidiaries [Member]	'	'
Variable Interest Entity [Line Items]	'	'
VIE interests carrying value	58.1	49.5
VIE interest maximum loss exposure	$58.10	'

Segment_Information_Details_Te

Segment Information (Details Textual) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014
Segment Reporting Information [Line Items]	'	'
Number of operating segments	'	4
Workers Compensation [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Worker's compensation SPC percentage ceded	100.00%	100.00%
Lloyds Syndicate [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Proportion of Capital Provided to support Lloyd's Syndicate 1729	58.00%	58.00%
Specialty Property and Casualty [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Premiums Ceded To Lloyd's Syndicate Segment	$1.10	$1.60

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Net premiums earned	$177,028	$133,598	$525,061	$398,528
Net investment income	32,830	33,889	92,788	99,282
Equity in earnings (loss) of unconsolidated subsidiaries	298	-305	2,767	-3,500
Net realized gains (losses)	-8,131	12,500	7,659	47,650
Other income	1,808	1,804	6,055	5,305
Gain on acquisition	0	494	0	35,986
Net losses and loss adjustment expenses	-99,222	-61,637	-287,643	-189,872
Underwriting, policy acquisition and operating expenses	-54,185	-33,348	-158,856	-105,592
Segregated portfolio cells dividend expense	483	0	-2,355	0
Interest expense	-3,606	-322	-10,697	-1,085
Income tax expense (benefit)	-12,525	-23,316	-43,328	-60,044
Segment operating results	34,778	63,357	131,451	226,658
Depreciation and amortization	12,312	9,920	36,286	34,364
Specialty P&C [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net premiums earned	123,791	133,598	374,704	398,528
Other income	1,071	1,225	4,167	3,902
Net losses and loss adjustment expenses	-63,639	-61,637	-191,263	-189,872
Underwriting, policy acquisition and operating expenses	-33,814	-30,708	-101,044	-95,907
Segment operating results	27,409	42,478	86,564	116,651
Depreciation and amortization	2,334	990	6,708	4,845
Workers Compensation [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net premiums earned	49,792	0	143,960	0
Other income	179	0	503	0
Net losses and loss adjustment expenses	-33,046	0	-91,975	0
Underwriting, policy acquisition and operating expenses	-14,785	0	-45,379	0
Segregated portfolio cells dividend expense	483	'	-2,355	'
Segment operating results	2,623	0	4,754	0
Depreciation and amortization	1,602	0	4,384	0
Lloyds Syndicate [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net premiums earned	3,445	0	6,397	0
Net investment income	120	0	244	0
Other income	-79	'	-79	'
Net losses and loss adjustment expenses	-2,537	'	-4,405	'
Underwriting, policy acquisition and operating expenses	-2,584	0	-5,999	0
Segment operating results	-1,635	0	-3,842	0
Depreciation and amortization	157	0	329	0
Corporate [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Net investment income	32,710	33,889	92,544	99,282
Equity in earnings (loss) of unconsolidated subsidiaries	298	-305	2,767	-3,500
Net realized gains (losses)	-8,131	12,500	7,659	47,650
Other income	824	579	1,856	1,410
Gain on acquisition	'	494	'	35,986
Underwriting, policy acquisition and operating expenses	-3,189	-2,640	-6,826	-9,692
Interest expense	-3,606	-322	-10,697	-1,085
Income tax expense (benefit)	-12,525	-23,316	-43,328	-60,044
Segment operating results	6,381	20,879	43,975	110,007
Depreciation and amortization	8,219	8,930	24,865	29,519
Eliminations [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Other income	-187	0	-392	-7
Underwriting, policy acquisition and operating expenses	187	0	392	7
Segment operating results	$0	$0	$0	$0

Segment_Information_Details_1

Segment Information (Details 1) (USD $)	3 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Segment Reporting Information [Line Items]	'		'	'		'
Net premiums earned	$177,028		$133,598	$525,061		$398,528
Specialty P&C [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Ceded premiums earned	-13,655	[1]	-10,682	-36,110	[1]	-30,256
Net premiums earned	123,791		133,598	374,704		398,528
Workers Compensation [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Ceded premiums earned	-6,898		0	-15,995		0
Net premiums earned	49,792		0	143,960		0
Lloyds Syndicate [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Ceded premiums earned	-640		0	-713		0
Net premiums earned	3,445		0	6,397		0
Healthcare professional liability [Member] | Specialty P&C [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Gross premiums earned	120,623		128,532	361,179		382,678
Legal professional liability [Member] | Specialty P&C [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Gross premiums earned	7,145		6,849	21,147		20,328
Medical technology and life sciences product liability [Member] | Specialty P&C [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Gross premiums earned	9,258		8,436	27,043		24,442
Other [Member] | Specialty P&C [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Gross premiums earned	420		463	1,445		1,336
Traditional business [Member] | Workers Compensation [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Gross premiums earned	42,345		0	119,702		0
Alternative market business [Member] | Workers Compensation [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Gross premiums earned	14,345		0	40,253		0
Property, Liability and Casualty Insurance Product Line [Member] | Lloyds Syndicate [Member]	'		'	'		'
Segment Reporting Information [Line Items]	'		'	'		'
Gross premiums earned	$4,085	[1]	$0	$7,110	[1]	$0
[1]	Includes premium ceded from the Specialty P&C Segment to the Lloyd's Syndicate Segment of $1.1 million for the three months and $1.6 million for nine months ended September 30, 2014, respectively.