Tower Group International (TWGP) 10-Q 26 Nov 13 2013 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2013	Nov. 21, 2013
Document Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'TWGP	'
Entity Registrant Name	'Tower Group International, Ltd.	'
Entity Central Index Key	'0001289592	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	57,429,099

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Available-for-sale investments, at fair value:	'	'
Fixed-maturity securities	$2,289,545	$2,344,711
Total investments	2,517,362	2,553,505
Cash and cash equivalents	108,535	102,269
Investment income receivable	26,182	25,332
Investment in unconsolidated affiliate	76,196	71,894
Premiums receivable	392,433	412,045
Reinsurance recoverable on paid losses	27,333	17,609
Reinsurance recoverable on unpaid losses	690,069	459,457
Prepaid reinsurance premiums	126,159	63,923
Deferred acquisition costs, net	192,887	181,198
Intangible assets	99,507	106,768
Goodwill	55,540	241,458
Funds held by reinsured companies	890,186	137,545
Other assets	465,548	338,769
Total assets	5,667,937	4,711,772
Liabilities	'	'
Loss and loss adjustment expenses	2,552,351	1,895,679
Unearned premium	998,624	921,271
Reinsurance balances payable	46,442	40,569
Funds held under reinsurance agreements	657,275	98,581
Other liabilities	350,838	296,960
Deferred income taxes	20,282	24,763
Debt	451,224	449,731
Total liabilities	5,077,036	3,727,554
Contingencies (Note 18)	'	'
Shareholders' equity	'	'
Common stock ($0.01 par value; 100,000,000 shares authorized, 57,437,157 and 53,048,011 shares issued, and 57,429,099 and 43,513,678 shares outstanding)	574	530
Treasury stock (8,058 and 9,534,333 shares)	-17	-181,435
Paid-in-capital	812,547	780,036
Accumulated other comprehensive income	9,060	82,756
Retained earnings (accumulated deficit)	-242,930	268,171
Tower Group International, Ltd. shareholders' equity	579,234	950,058
Noncontrolling interests	11,667	34,160
Total shareholders' equity	590,901	984,218
Total liabilities and shareholders' equity	5,667,937	4,711,772
Tower	'	'
Available-for-sale investments, at fair value:	'	'
Fixed-maturity securities	2,035,770	2,064,148
Equity securities	134,650	140,695
Short-term investments	13,379	4,750
Other invested assets	77,038	57,786
Liabilities	'	'
Loss and loss adjustment expenses	2,433,087	1,759,888
Reciprocal Exchanges	'	'
Available-for-sale investments, at fair value:	'	'
Fixed-maturity securities	253,775	280,563
Equity securities	2,750	5,563
Cash and cash equivalents	12,744	9,782
Investment income receivable	2,609	2,610
Premiums receivable	45,385	44,285
Reinsurance recoverable on paid losses	6,556	682
Reinsurance recoverable on unpaid losses	24,897	52,389
Prepaid reinsurance premiums	19,988	17,803
Deferred acquisition costs, net	9,912	11,364
Intangible assets	6,596	6,854
Other assets	1,687	1,559
Liabilities	'	'
Loss and loss adjustment expenses	119,264	135,791
Unearned premium	102,492	103,216
Reinsurance balances payable	7,266	6,979
Funds held under reinsurance agreements	0	500
Other liabilities	10,851	21,321
Deferred income taxes	$19,818	$19,719

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Fixed-maturity securities, amortized cost	$2,229,407	$2,190,186
Cash and cash equivalents	108,535	102,269
Investment income receivable	26,182	25,332
Premiums receivable	392,433	412,045
Reinsurance recoverable on paid losses	27,333	17,609
Reinsurance recoverable on unpaid losses	690,069	459,457
Prepaid reinsurance premiums	126,159	63,923
Deferred acquisition costs, net	192,887	181,198
Intangible assets	99,507	106,768
Other assets	465,548	338,769
Loss and loss adjustment expenses	2,552,351	1,895,679
Unearned premium	998,624	921,271
Reinsurance balances payable	46,442	40,569
Funds held under reinsurance agreements	657,275	98,581
Other liabilities	350,838	296,960
Deferred income taxes	20,282	24,763
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	57,437,157	53,048,011
Common stock, shares outstanding	57,429,099	43,513,678
Treasury stock, shares	8,058	9,534,333
Tower	'	'
Fixed-maturity securities, amortized cost	1,980,652	1,926,236
Equity securities, cost	127,598	144,204
Short-term investments, cost	13,415	4,749
Loss and loss adjustment expenses	2,433,087	1,759,888
Reciprocal Exchanges	'	'
Fixed-maturity securities, amortized cost	248,755	263,950
Equity securities, cost	2,751	5,144
Cash and cash equivalents	12,744	9,782
Investment income receivable	2,609	2,610
Premiums receivable	45,385	44,285
Reinsurance recoverable on paid losses	6,556	682
Reinsurance recoverable on unpaid losses	24,897	52,389
Prepaid reinsurance premiums	19,988	17,803
Deferred acquisition costs, net	9,912	11,364
Intangible assets	6,596	6,854
Other assets	1,687	1,559
Loss and loss adjustment expenses	119,264	135,791
Unearned premium	102,492	103,216
Reinsurance balances payable	7,266	6,979
Funds held under reinsurance agreements	0	500
Other liabilities	10,851	21,321
Deferred income taxes	$19,818	$19,719

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues	'	'	'	'
Net premiums earned	$418,364	$460,153	$840,250	$880,311
Ceding commission revenue	11,933	10,080	26,084	15,243
Insurance services revenue	532	1,359	660	1,856
Policy billing fees	3,321	3,000	6,471	6,134
Net investment income	28,402	31,781	58,719	65,724
Net realized investment gains (losses):	'	'	'	'
Other-than-temporary impairments	-4,456	-2,270	-5,145	-5,246
Portion of loss recognized in other comprehensive income	'	286	'	286
Other net realized investment gains	2,422	2,003	9,962	8,307
Total net realized investment gains (losses)	-2,034	19	4,817	3,347
Total revenues	460,518	506,392	937,001	972,615
Expenses	'	'	'	'
Loss and loss adjustment expenses	559,892	349,775	835,624	617,268
Commission expense	106,278	95,186	195,854	175,571
Other operating expenses	88,308	78,100	172,701	155,171
Acquisition-related transaction costs	665	720	19,721	1,982
Interest expense	7,635	7,902	15,443	16,513
Total expenses	762,778	531,683	1,239,343	966,505
Other income (expense)	'	'	'	'
Equity income in unconsolidated affiliate	7,838	'	7,966	'
Goodwill impairment	-214,049	'	-214,049	'
Income (loss) before income taxes	-508,471	-25,291	-508,425	6,110
Income tax expense (benefit)	-1,930	-8,919	-3,520	306
Net income (loss)	-506,541	-16,372	-504,905	5,804
Less: Net income (loss) attributable to Noncontrolling interests	801	437	-10,480	3,448
Net income (loss) attributable to Tower Group International, Ltd.	($507,342)	($16,809)	($494,425)	$2,356
Earnings (loss) per share attributable to Tower Group International, Ltd. shareholders:	'	'	'	'
Basic	($8.88)	($0.39)	($9.61)	$0.05
Diluted	($8.88)	($0.39)	($9.61)	$0.05
Weighted average common shares outstanding:	'	'	'	'
Basic	57,135	43,289	51,487	43,340
Diluted	57,135	43,289	51,487	43,410
Dividends declared and paid per common share	$0.17	$0.17	$0.34	$0.34

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net income (loss)	($506,541)	($16,372)	($504,905)	$5,804
Other comprehensive income (loss) before tax	'	'	'	'
Gross unrealized investment holding gains (losses) arising during periods	-80,963	8,613	-81,334	33,585
Less: Reclassification adjustment for investment (gains) losses included in net income	1,938	-19	-4,529	-3,347
Portion of other-than-temporary impairment losses recognized in other comprehensive income	'	-286	'	-286
Cumulative translation adjustment	-53	'	-3,664	'
Deferred gain (loss) on cash flow hedge	2,220	-1,160	3,818	-1,391
Other comprehensive income (loss) before tax	-76,858	7,148	-85,709	28,561
Income tax benefit (expense) related to items of other comprehensive income (loss)	-2,721	-2,272	'	-9,010
Other comprehensive income (loss), net of income tax	-79,579	4,876	-85,709	19,551
Comprehensive income (loss)	-586,120	-11,496	-590,614	25,355
Less: Comprehensive income (loss) attributable to Noncontrolling interests	-9,526	2,992	-22,492	9,377
Comprehensive income (loss) attributable to Tower Group International, Ltd.	($576,594)	($14,488)	($568,122)	$15,978

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Shareholders' Equity (USD $)	Total	Common Stock	Treasury Stock	Paid-in Capital	Accumulated Other Comprehensive Income (loss)	Retained Earnings (Accumulated Deficit)	Noncontrolling Interests
In Thousands
Balance at Dec. 31, 2011	$1,037,131	$526	($158,185)	$772,877	$63,053	$331,480	$27,380
Balance (in shares) at Dec. 31, 2011	'	52,626	'	'	'	'	'
Dividends declared	-14,680	'	'	'	'	-14,680	'
Stock based compensation (in shares)	'	364	'	'	'	'	'
Stock based compensation	2,233	4	-2,152	4,381	'	'	'
Repurchase of common stock	-20,987	'	-20,987	'	'	'	'
Net income (loss)	5,804	'	'	'	'	2,356	3,448
Transfer of assets to Reciprocal Exchange	'	'	'	-1,778	'	'	1,778
Other comprehensive income (loss)	19,551	'	'	'	13,622	'	5,929
Balance at Jun. 30, 2012	1,029,052	530	-181,324	775,480	76,675	319,156	38,535
Balance (in shares) at Jun. 30, 2012	'	52,990	'	'	'	'	'
Balance at Dec. 31, 2012	984,218	530	-181,435	780,036	82,756	268,171	34,160
Balance (in shares) at Dec. 31, 2012	'	53,048	'	'	'	'	'
Dividends declared	-16,676	'	'	'	'	-16,676	'
Stock based compensation (in shares)	'	245	'	'	'	'	'
Stock based compensation	6,085	3	-5,870	11,952	'	'	'
Merger Transaction with Canopius Bermuda (in shares)	'	14,026	'	'	'	'	'
Merger Transaction with Canopius Bermuda	207,347	140	'	207,207	'	'	'
Extinguishment of treasury stock in connection with Merger Transaction (in shares)	'	-9,882	'	'	'	'	'
Extinguishment of treasury stock in connection with Merger Transaction	'	-99	187,288	-187,189	'	'	'
Termination of convertible senior notes hedge and warrants	541	'	'	541	'	'	'
Net income (loss)	-504,905	'	'	'	'	-494,425	-10,480
Other comprehensive income (loss)	-85,709	'	'	'	-73,696	'	-12,013
Balance at Jun. 30, 2013	$590,901	$574	($17)	$812,547	$9,060	($242,930)	$11,667
Balance (in shares) at Jun. 30, 2013	'	57,437	'	'	'	'	'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012
Cash flows provided by (used in) operating activities:	'	'
Net income (loss)	($504,905)	$5,804
Adjustments to reconcile net income to net cash provided by (used in) operations:	'	'
Gain on investment in acquired unconsolidated affiliate	-7,966	'
Net realized investment (gains) losses	-4,817	-3,347
Depreciation and amortization	22,080	15,985
Goodwill impairment	214,049	'
Amortization of bond premium or discount	6,124	5,377
Amortization of restricted stock	12,622	4,382
Deferred income taxes	44,743	-1,786
Excess tax benefits from share-based payment arrangements	-1,108	'
Changes in operating assets and liabilities:	'	'
Investment income receivable	-850	-451
Premiums receivable	19,612	26,643
Reinsurance recoverable	228,391	22,871
Prepaid reinsurance premiums	90,195	-1,654
Deferred acquisition costs, net	-5,871	-16,649
Funds held by reinsured companies	-53,822	-64,213
Other assets	35,105	-4,511
Loss and loss adjustment expenses	26,059	69,720
Unearned premium	-92,610	33,280
Reinsurance balances payable	5,873	-6,376
Funds held under reinsurance agreements	-2,020	-5,584
Other liabilities	-52,376	-7,054
Net cash flows provided by (used in) operations	-21,492	72,437
Cash flows provided by (used in) investing activities:	'	'
Cash acquired in Merger Transaction	134,741	'
Purchase of fixed assets	-15,661	-19,426
Purchase - fixed-maturity securities	-815,579	-997,657
Purchase - equity securities	-796,800	-802,154
Short-term investments, net	18,309	'
Purchase of other invested assets	-19,252	-7,986
Sale of fixed-maturity securities	664,401	911,796
Maturity of fixed-maturity securities	79,230	199,867
Sale - equity securities	802,297	745,618
Change in restricted cash	-3,870	'
Net cash flows provided by (used in) investing activities	47,816	30,058
Cash flows provided by (used in) financing activities:	'	'
Proceeds from credit facility borrowings	'	20,000
Proceeds from convertible senior notes hedge termination	2,380	'
Payment for warrants termination	-1,000	'
Issuance of common stock under stock-based compensation programs	2	3
Excess tax benefits from share-based payment arrangements	1,106	228
Treasury stock acquired-net employee share-based compensation	-5,870	-2,152
Repurchase of Common Stock	'	-20,987
Dividends paid	-16,676	-14,680
Net cash flows provided by (used in) financing activities	-20,058	-17,588
Increase (decrease) in cash and cash equivalents	6,266	84,907
Cash and cash equivalents, beginning of period	102,269	114,098
Cash and cash equivalents, end of period	$108,535	$199,005

Nature_of_Business

Nature of Business	6 Months Ended
	Jun. 30, 2013
Nature of Business	'
	Note 1—Nature of Business
	Tower Group International, Ltd. (the “Company” or “Tower”) offers a broad range of commercial, specialty and personal property and casualty insurance products and services through its subsidiaries to businesses and to individuals. On March 13, 2013, the Company and Tower Group, Inc. (“TGI”) completed a merger transaction under which the Company, formerly known as Canopius Holdings Bermuda Limited (“Canopius Bermuda”), was re-named Tower Group International, Ltd. and became the ultimate parent company (the “Merger Transaction”). The Company’s common shares are publicly traded on the NASDAQ Global Select Market under the symbol “TWGP”, which was also the symbol of TGI common shares on that exchange prior to the Merger Transaction. See “Note 4 – Merger Transaction” for further discussion of the Merger Transaction and the Company’s succession to TGI as registrant.
	Significant Business Developments and Risks and Uncertainties
	Loss reserves recognized in the June 30, 2013 statement of operations reflect an increase in its loss and loss adjustment expense reserves of $326.7 million excluding the Reciprocal Exchanges relating to reserve strengthening associated with losses from prior accident years. This unfavorable loss development arose primarily from accident years 2008-2011 within the workers’ compensation, commercial multi-peril liability (“CMP”), other liability and commercial auto liability lines of business offset to some degree by favorable development from more recent years within the short tail property lines of business. In the second quarter of 2013, the Company performed a comprehensive update to its internal reserve study in response to continued observance in the second quarter of 2013 of higher than expected reported loss development. In conjunction with its comprehensive internal review, the Company also retained its consulting actuary to perform an independent reserve study covering lines of business comprising over 90% of the Company’s loss reserves. Since 2010, the Company has changed the mix of business by reducing the amount of program and middle market workers’ compensation and liability business that it underwrites. For additional detail of this reserve charge by accident year, business segment and line of business please see “Note 9 - Loss and Loss Adjustment Expense”.
	The reserve strengthening was viewed by the Company as an event or circumstance that required the Company to perform a detailed quantitative analysis of whether its recorded goodwill was impaired. After performing the quantitative analysis, it was determined that $214.0 million of goodwill, which represents all of the goodwill allocated to the Commercial Insurance reporting unit, was impaired. Accordingly, the consolidated statement of operations in the second quarter of 2013 includes a non-cash charge of $214.0 million associated with the write-down of goodwill. See “Note 5 – Goodwill and Intangible Assets” for additional detail on the Goodwill impairment.
	As a result of the reserve strengthening, the Company is expecting its U.S. based operations to have a pre-tax loss for 2013, which would result in a three-year cumulative tax loss position on its U.S. subsidiaries. After considering this negative evidence and uncertainty regarding the Company’s ability to generate sufficient future taxable income in the United States, the Company concluded that it should not recognize any net deferred tax assets (comprised principally of net operating loss carryforwards). The Company, therefore provided a full valuation allowance against its deferred tax asset at June 30, 2013.
	Reinsurance Agreements
	On October 1, 2013, Tower announced that it entered into agreements with three reinsurers, Arch Reinsurance Ltd. (“Arch”), Hannover Re (Ireland) Plc. (“Hannover”) and Southport Re (Cayman), Ltd. (“Southport Re”).These agreements provided for surplus enhancement and improved certain financial leverage ratios, while increasing the Company’s financial flexibility. The agreements with Arch and Hannover each consist of one reinsurance agreement while the arrangement with Southport Re consists of several reinsurance agreements. Each of these is described below.
	The first agreement was between Tower Insurance Company of New York (“TICNY”), on its behalf and on behalf of each of its pool participants, and Arch. Under this multi-line quota share agreement, TICNY will cede 17.5% on a quota share of certain commercial automobile liability, commercial multi-peril property, commercial multi-peril liability and brokerage other liability (mono line liability) businesses. The agreement covers losses occurring on or after July 1, 2013 for policies in-force as at June 30, 2013 and policies written or renewed from July 1, 2013 to December 31, 2013. The agreement has a special termination clause whereby either party may terminate the agreement upon the occurrence of certain circumstances, including an A.M. Best financial strength rating downgrade to below A-. As noted below, A.M. Best downgraded Tower’s financial strength rating to B++. Neither party has provided notice to terminate the agreement.
	The second agreement was between TICNY, on its behalf and on behalf of each of its pool participants, and Hannover. Under this multi-line quota share agreement, TICNY will cede 14% on a quota share of certain brokerage commercial automobile liability, brokerage commercial multi-peril property, brokerage commercial multi-peril liability, brokerage other liability (mono line liability) and brokerage workers’ compensation businesses. The agreement covers losses occurring on or after July 1, 2013 for policies in-force as at June 30, 2013 and policies written or renewed from July 1, 2013 to December 31, 2013. The agreement has a special termination clause whereby either party may terminate the agreement upon the occurrence of certain circumstances, including an A.M. Best financial strength rating downgrade to below A-. As noted below, A.M. Best downgraded Tower’s financial strength rating to B++. Neither party has provided notice to terminate the agreement.
	The third reinsurance arrangement with Southport Re consisted of two separate reinsurance agreements with TICNY, on its behalf and on behalf of each of its pool participants, and a third reinsurance agreement with Tower Reinsurance, Ltd. (“TRL”). Under the first of the agreements with TICNY, TICNY ceded to Southport Re a 30% quota share of its workers’ compensation and employer’s liability business. The agreement covers losses occurring on or after July 1, 2013 for policies in force at June 30, 2013 and policies written or renewed during the term of the agreement. Under the second of these agreements with TICNY, an aggregate excess of loss agreement, Southport Re assumed a portion of the losses incurred by TICNY on its workers’ compensation and employer’s liability business between January 1, 2011 and June 30, 2013, but paid by TICNY on or after June 1, 2013. Finally, TRL, a wholly-owned Bermuda-domiciled reinsurance subsidiary of Tower, also entered into an aggregate excess of loss agreement with Southport Re, in which Southport Re assumed a portion of the losses incurred by TRL on its assumed workers’ compensation and employer’s liability business between January 1, 2011 and June 30, 2013, but paid by TRL on or after June 1, 2013. The agreement has a special termination clause whereby either party may terminate the agreement upon the occurrence of certain circumstances, including an A.M. Best financial strength rating downgrade to below A-. As noted below, A.M. Best downgraded Tower’s financial strength rating to B++. Neither party has provided notice to terminate the agreement.
	A.M. Best, Fitch and Demotech Downgrade the Company’s Financial Strength and Issuer Credit Ratings
	On October 7, 2013, Fitch Ratings (“Fitch”), downgraded Tower’s Issuer Default Rating from “BBB” to “B” and Tower’s insurance subsidiaries’ Insurer Financial Strength ratings from “A-” to “BB”. The ratings will continue to remain on negative watch until, at the earliest, the completion of Tower’s exploration of strategic alternatives.
	On October 8, 2013, A.M. Best Company (“A.M. Best”), lowered Tower’s issuer credit, as well as its financial strength ratings, from “A-” (Excellent) to “B++” (Good). The ratings remain under review with negative implications pending further discussions between A.M. Best and Tower’s management.
	On October 7, 2013, Demotech, Inc. (“Demotech”) lowered its rating on TICNY and three other U.S. based insurance subsidiaries (Kodiak Insurance Company, Massachusetts Homeland Insurance Company and York Insurance Company of Maine) from A’ (A prime) to A (A exceptional). In addition, Demotech removed its previous A’ (A prime) rating on six other U.S. based insurance subsidiaries (CastlePoint Florida Insurance Company, CastlePoint Insurance Company, CastlePoint National Insurance Company, Hermitage Insurance Company, North East Insurance Company and Preserver Insurance Company). Demotech also affirmed its A ratings on Adirondack Insurance Exchange, New Jersey Skylands Insurance Association, New Jersey Skylands Insurance Company and Mountain Valley Indemnity Company.
	Management expects these rating actions, in combination with other items that have impacted the Company in the second quarter of 2013, to result in a decrease in the amount of premiums the insurance subsidiaries are able to write. The net written premiums in the Commercial Insurance segment were $169.1 million and $343.6 million for the three and six months ended June 30, 2013, respectively. The net written premiums in the Specialty Insurance and Reinsurance segment were $103.7 million and $306.6 million for the three and six months ended June 30, 2013, respectively. Business written through certain program underwriting agents requires an A.M. Best rating of A- or greater.
	In addition, one of Tower’s ceding companies requested as a result of contractual provisions that $26.3 million of additional collateral be provided to support the recoverability of their reinsurance receivable from Tower. The $26.3 million was funded in October 2013. Tower’s U.S. based insurance subsidiaries are also required to post collateral for various statutory purposes, and such requests are received from time to time from various regulatory authorities.
	Statutory Capital
	The Company is required to maintain minimum capital and surplus for each of its insurance subsidiaries.
	U.S. based insurance companies are required to maintain capital and surplus above Company Action Level, which is a calculated capital and surplus number using a risk-based formula adopted by the state insurance regulators. The basis for this formula is the National Association of Insurance Commissioners’ (“NAIC’s”) risk-based capital (“RBC”) system and is designed to measure the adequacy of a U.S. regulated insurer’s statutory capital and surplus compared to risks inherent in its business. If an insurance entity falls into Company Action Level, its management is required to submit a comprehensive financial plan that identifies the conditions that contributed to the financial condition. This plan must contain proposals to correct the financial problems and provide projections of the financial condition, both with and without the proposed corrections. The plan must also outline the key assumptions underlying the projections and identify the quality of, and problems associated with, the underlying business. Depending on the level of actual capital and surplus in comparison to the Company Action Level, the state insurance regulators could increase their regulatory oversight, restrict the placement of new business, or place the company under regulatory control. Bermuda based insurance entities minimum capital and surplus requirements are calculated from a solvency formula prescribed by the Bermuda Monetary Authority (the “BMA”).
	As of June 30, 2013, Tower Reinsurance, Ltd. (“TRL”), one the Company’s two Bermuda-based reinsurers had capital and surplus that did not meet the minimum capital and surplus requirements of the BMA.
	The Company has discussed with the BMA its intention to combine a substantial portion of the business and the capital of CastlePoint Reinsurance Company (“CastlePoint Re”), the Company’s other Bermuda based reinsurer, with TRL. Through this combination, management believes that the combined entity’s capital would meet the minimum capital and surplus thresholds determined by the BMA. The Company is currently developing this plan and expects to deliver this plan to its Bermuda regulators in the next several weeks. The Company cannot provide assurance that it will be successful in pursuing this alternative. Should the business combination not be approved, TRL would be operating at a capital level that is below the regulatory minimums as designated by the BMA. As such, TRL may be subject to significant additional regulatory oversight or, in the event that such oversight did not satisfy the BMA, placed into liquidation.
	Tower has in place several intercompany reinsurance transactions between its U.S. based insurance subsidiaries and its Bermuda based insurance subsidiaries. The U.S. based insurance subsidiaries have historically reinsured on a quota share basis obligations to CastlePoint Re. The 2013 obligations that CastlePoint Re assumes from the U.S. based insurance subsidiaries are then retroceded to TRL. In addition, CastlePoint Re also entered into a loss portfolio transaction with TRL where its reserves associated with the U.S. insurance subsidiary business for underwriting years prior to 2013 were all transferred to TRL. Therefore, TRL recorded $175 million of reserve strengthening on its balance sheet as of June 30, 2013 and, consequently, the financial result of such development was a reduction in the capital of TRL to $8.3 million at June 30, 2013. In addition TRL is required to collateralize the additional $175 million of assumed reserves in a trust for the benefit of TICNY, the lead pool company of the U.S. insurance companies. TRL had unencumbered liquid assets of $96 million at June 30, 2013, and during October of 2013, TRL commuted two reinsurance treaties which provided an additional $79 million in unencumbered assets.
	The funding of the trust to support TICNY’s reinsurance recoverable has not yet occurred and requires approval by the BMA. The Company can provide no assurance that it will be successful in finalizing the business combination or in funding the trust. If the trust funding is not approved, 1) the statutory capital of TICNY would be at a level that could result in the New York Department of Financial Services placing TICNY under regulatory control; and 2) Tower Group, Inc. could violate the revised debt covenants of the bank credit facility at December 31, 2013, which violation, if not waived, would result in a cross default of our convertible notes. Statutory capital and surplus would be further reduced by whatever amounts are due from CastlePoint Re or from TRL that are not supported by assets held in trust. At June 30, 2013, all other U.S. based insurance subsidiaries maintained capital and surplus above company action level.
	Two insurance subsidiaries that do not constitute “significant subsidiaries” of the Company under Regulation S-X are in discussions with the insurance regulatory authority in their state of domicile with respect to the imposition of restrictions on the operation of their businesses. These discussions may result in such subsidiaries’ agreeing to provide the regulatory authority with increased information with respect to their business, operations and financial condition, as well as limitations on payments and transactions outside the ordinary course of business and material changes in their management and related matters.
	Liquidity
	TGI is the obligor under the bank credit facility agreement dated as of February 15, 2012, as amended, with Bank of America, N.A. and other lenders named therein ($70 million is outstanding as of June 30,2013) and the Convertible Senior Notes (“Notes”) due September 2014 ($150 million par outstanding as of June 30,2013). The indebtedness of TGI is guaranteed by Tower Group International, Ltd. (“TGIL”), as well as several of TGIL’s non-insurance subsidiaries.
	TGI amended its credit facility on October 11, 2013, and agreed to several restrictions under the credit facility, including:
		•	To not enter into any new borrowings under the credit facility;
		•	To pledge to the lending banks any proceeds of new capital raises by TGI or TGIL until such time as the credit facility is paid in full;
		•	To pledge to the lending banks proceeds from any sales of assets occurring at TGI; and
		•	To submit to regulatory authorities, as appropriate, a request for approval to pledge the capital stock of the U.S. based and Bermuda based insurance subsidiaries.
	In addition, the following financial covenants are included in the credit facility:
		•	Minimum Consolidated Net Worth is the greater of $553,400,000 or 90 % of Consolidated Net Worth as of June 30, 2013; this covenant increases by 90% of any new capital plus 50% of Net Income above $20,000,000;
		•	Debt to capitalization ratio limit of 46%;
		•	Minimum risk based capital ratio of 175% at December 31, 2013 for Tower Insurance Company of New York and any other insurance subsidiary that exceeds 10% of the consolidated statutory surplus of all insurances subsidiaries;
		•	Bermuda enhanced minimum capital requirement of 150% for CastlePoint Re at December 31, 2013 and 110% for TRL;
		•	Minimum statutory surplus for all insurance companies of the greater of $419,000,000 or 85% of Combined Surplus at June 30, 2013. The Company was in compliance with this covenant as of June 30, 2013; and
		•	Independent accountant’s annual report shall not be subject to any “going concern” or like qualification or exception. This financial covenant will remain in effect for the year ending December 31, 2013. Although the independent accountant’s report on the consolidated financial statements for the years ended December 31, 2010, 2011 and 2012 contains a “going concern” explanatory paragraph, on November 14, 2013, the Company received a waiver from the lenders under the credit facility in respect of such “going concern” paragraph.
	Tower currently is in compliance with all covenants contained in the credit facility.
	The credit facility matures on May 30, 2014, at which point any unpaid balance becomes due.
	The Company is evaluating potential opportunities to raise additional capital in private sales transactions as well as through other strategic alternatives currently being considered by TGIL’s Board of Directors, and intends to liquidate certain investments at TGI to repay the credit facility. Should the Company default on the credit facility and should such default not be waived by the credit banks, it would cause an acceleration of the maturity of the Notes, and such notes would become due concurrently with the unpaid balance on the credit facility.
	The Company’s plan to repay the Notes includes a combination of using proceeds from the sale of assets held at TGI as well as using proceeds generated by future strategic alternatives being evaluated by TGIL’s Board of Directors, and to the extent necessary, issuing debt and/or equity securities to pay down the principal of the Notes. To the extent that such asset sales and debt securities issuances are not executed or are not successful, the Company may seek to sell certain of its operating assets to satisfy this obligation. The Company can provide no assurance that it will be successful in finalizing the liquidation of the assets held at TGI, issuing new debt and/or equity securities or selling certain of its operating assets.
	As of June 30, 2013, there are $235 million of subordinated debentures outstanding. The subordinated debentures do not have financial covenants that would cause an acceleration of their stated maturities. The earliest stated maturity date is on a $10 million debenture, with a stated maturity in May 2033. The Company has the ability to defer interest payments on its subordinated debentures for up to twenty quarters.
	There are currently no commitments or assurances to raise additional capital, execute on any strategic alternatives or to liquidate certain investments at prices sufficient to liquidate the credit facility. In addition, there can be no guarantees that the Company will be able to remedy current statutory capital deficiencies in certain insurance subsidiaries or maintain adequate levels of statutory capital in the future. Consequently, there is substantial doubt about the Company’s ability to continue as a going concern. Should the Company no longer continue to support its capital or liquidity needs, or should the Company be unable to successfully execute the above mentioned initiatives, the above items would have a material adverse effect on its business, results of operations and financial position.
	The Company and certain of its senior officers have been named as defendants in several class action lawsuits instituted against them by certain shareholders. See “Note 18 – Contingences” for additional detail on such litigation.
	Reorganization
	In the second quarter of 2013, the Company changed the presentation of its business results by allocating its specialty business and assumed reinsurance previously reported in the Commercial Insurance segment to a new Specialty Insurance and Reinsurance segment. In addition, the Company redefined the Personal Insurance segment to include its management companies, which provide certain services to the Reciprocal Exchanges for a management fee. The Reciprocal Exchanges continue to be included in the Personal Insurance segment and transactions between the management companies and the Reciprocal Exchanges have been eliminated. The management companies were previously reported in the Insurance Services segment. The Company will no longer present an Insurance Services segment. These changes in presentation reflect the way management organizes the Company for operating decisions and assessing profitability subsequent to the Merger Transaction. The prior period segment disclosures have been restated to conform to the current presentation.
	Following the change in presentation described above, the Company now operates in three business segments: Commercial Insurance, Specialty Insurance and Reinsurance and Personal Insurance:
		•	Commercial Insurance (“Commercial”) segment offers a broad range of standard commercial lines property and casualty insurance products to businesses distributed through a network of retail and wholesale agents on both an admitted and non-admitted basis;
		•	Specialty Insurance and Reinsurance (“Specialty and Reinsurance”) segment offers (i) specialty commercial lines property casualty insurance products distributed through program underwriting agents and (ii) assumed reinsurance; and
		•	Personal Insurance (“Personal”) segment offers a broad range of personal lines property and casualty insurance products to individuals distributed through a network of retail and wholesale agents. Also included in the Personal Insurance segment are the results of the Reciprocal Exchanges.
	See “Note 17 – Segment Information” for further information on the composition of the Company’s operating and reportable segments.

Restatement_of_Previously_Issu

Restatement of Previously Issued Financial Statements	6 Months Ended
	Jun. 30, 2013
Restatement of Previously Issued Financial Statements	'
	Note 2—Restatement of previously issued financial statements
	On November 14, 2013, Tower Group International, Ltd. (“Tower” or the “Company”) issued a Current Report on Form 8-K stating that it had reached a determination to restate Tower’s audited annual consolidated financial statements as of and for the years ended December 31, 2011 and 2012 contained in Amendment No. 1 to Tower’s Annual Report on Form 10-K for the year ended December 31, 2012, which was filed with the SEC on March 13, 2013 (the “2012 Form 10-K/A”), and that such financial statements should no longer be relied upon. In addition, Tower will revise its (i) audited annual consolidated financial statements for the year ended December 31, 2010 contained in the 2012 Form 10-K/A and (ii) unaudited interim consolidated financial statements as of and for the three months ended March 31, 2013 and 2012 contained in its Quarterly Report on Form 10-Q for the Quarter ended March 31, 2013, which was filed with the SEC on May 10, 2013. Following management review of the matter with the Audit Committee of Tower’s Board of Directors (the “Audit Committee”), and upon management’s recommendation, the Audit Committee reached a conclusion on November 7, 2013 that previously issued financial statements of the Company covering one or more periods for which the Company is required to provide financial statements need to be revised or restated and may no longer be relied upon because of the inadvertent mistakes described below. At such meeting, the Audit Committee authorized the Company’s Chief Financial Officer and Chief Accounting Officer to determine, in consultation with the Company’s independent registered public accounting firm, the specific financial statements that should be revised or restated and should no longer be relied upon. Acting upon such authority, on November 12, 2013, these officers reached a conclusion, and advised Tower’s Board of Directors, as to the specific financial statements that need to be so revised or restated and should no longer be relied upon, as described above. The Company had previously determined and announced on October 7, 2013 that its June 30, 2013 loss reserves were strengthened by approximately $365 million. The Company then undertook to review its reserve analyses for prior years. During this evaluation, the Company considered its historical loss reserve analyses and the analyses of its independent actuaries and reviewed and discussed its conclusions with its independent registered public accounting firm. Upon completion of this evaluation, the Company determined that inadvertent mistakes in classification of insurance premiums by line of business used in the loss reserving process resulted in (1) an increase in the loss and loss adjustment expenses of $9.6 million, $21.7 million and $5.7 million, for the years ended December 31, 2012, 2011 and 2010, respectively, and (2) a decrease in the reinsurance recoverables on unpaid losses asset balance by $37.0 million, $27.4 million and $5.7 million as of December 31, 2012, 2011 and 2010, respectively.
	In addition, subsequent to the announcement on October 7, 2013, the Company identified errors in its historical premiums receivable balances due to inadvertent mistakes in its premiums receivable reconciliation process. This resulted in (1) a decrease of premiums receivable asset balance of $11.0 million, $10.0 million, $5.6 million and $7.2 million as of the years ended December 31, 2012, 2011, 2010 and 2009, respectively, and (2) an increase (decrease) of other operating expenses of $1.0 million, $4.4 million, ($1.6) million and $7.2 million for the years ended December 31, 2012, 2011, 2010 and 2009, respectively. The Company has also corrected other immaterial adjustments that were initially recorded in the period they were identified.
	The effect of the restatement on the consolidated balance sheets are presented in the table below:
		December 31, 2012
	($ in thousands, except par value and share amounts)	As			Restated			Effect of
		Previously						Adjustments
		Reported
	Assets
	Total investments		2,554,505			2,553,505			(1,000	)
	Cash and cash equivalents		100,293			102,269			1,976
	Investment income receivable		25,332			25,332			—
	Investment in unconsolidated affiliate		70,830			71,894			1,064
	Premiums receivable		422,112			412,045			(10,067	)
	Reinsurance recoverable on paid losses		17,609			17,609			—
	Reinsurance recoverable on unpaid losses		496,192			459,457			(36,735	)
	Prepaid reinsurance premiums		63,923			63,923			—
	Deferred acquisition costs, net		180,941			181,198			257
	Intangible assets		106,768			106,768			—
	Goodwill		241,458			241,458			—
	Funds held by reinsured companies		137,545			137,545			—
	Other assets		331,506			338,769			7,263
	Total Assets		4,749,014		$	4,711,772		$	(37,242	)
	Liabilities
	Loss and loss adjustment expenses		1,895,073		$	1,895,679		$	606
	Unearned premium		920,859			921,271			412
	Reinsurance balances payable		40,569			40,569			—
	Funds held under reinsurance agreements		98,581			98,581			—
	Other liabilities		292,239			296,960			4,721
	Deferred income taxes		36,464			24,763			(11,701	)
	Debt		449,731			449,731			—
	Total liabilities		3,733,516			3,727,554			(5,962	)
	Contingencies		—			—			—
	Stockholders’ equity
	Common stock		530			530			—
	Treasury stock		(181,435	)		(181,435	)		—
	Paid-in-capital		780,036			780,036			—
	Accumulated other comprehensive income		83,406			82,756			(650	)
	Retained earnings		298,299			268,171			(30,128	)
	Tower Group, Inc. stockholders’ equity		980,836			950,058			(30,778	)
	Noncontrolling interests		34,662			34,160			(502	)
	Total stockholders’ equity		1,015,498			984,218			(31,280	)
	Total liabilities and stockholders’ equity		4,749,014		$	4,711,772		$	(37,242	)

Accounting_Policies_and_Basis_

Accounting Policies and Basis of Presentation	6 Months Ended
	Jun. 30, 2013
Accounting Policies and Basis of Presentation	'
	Note 3—Accounting Policies and Basis of Presentation
	Basis of Presentation
	The Merger Transaction was accounted for as a reverse acquisition, under which TGI was identified and treated as the accounting acquirer. As such, the Company’s unaudited consolidated financial statements include the accounts and operations of TGI and its insurance subsidiaries, managing general agencies and management companies as its historical financial statements, with the results of Tower Group International, Ltd., as accounting acquiree, being included from March 13, 2013, the effective date of the Merger Transaction. The unaudited consolidated financial statements also include the accounts of Adirondack Insurance Exchange, a New York reciprocal insurer, and New Jersey Skylands Insurance Association, a New Jersey reciprocal insurer (together, the “Reciprocal Exchanges”). The Company does not own the Reciprocal Exchanges but manages their business operations through its wholly-owned management companies.
	The accompanying unaudited consolidated financial statements included in this report have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and with the instructions to Securities and Exchange Commission (“SEC”) Form 10-Q and Article 10 of SEC Regulation S-X. The principles for condensed interim financial information do not require the inclusion of all the information and footnotes required by GAAP for complete financial statements. Therefore, these financial statements should be read in conjunction with TGI’s consolidated financial statements as of and for the year ended December 31, 2012 and notes thereto included in TGI’s Amendment No. 2 to the Annual Report on Form 10-K for the year ended December 31, 2012. The accompanying consolidated financial statements have not been audited by an independent registered public accounting firm in accordance with standards of the Public Company Accounting Oversight Board (United States) but, in the opinion of management, such financial statements include all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the Company’s financial position, results of operations and cash flows. All intercompany transactions have been eliminated in consolidation.
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Moreover, the results of operations for the six months ended June 30, 2013 may not be indicative of the results that may be expected for the year ending December 31, 2013.
	Intercompany transactions
	In the first quarter of 2012, the Company transferred a licensed insurance subsidiary shell to the Reciprocal Exchanges and received cash for its statutory book value. At the date of the transfer, the Company’s GAAP carrying basis in this subsidiary exceeded the statutory book value and the transfer resulted in a loss to the Company of $1.8 million. Since this was a non-recurring transaction between entities under common control, assets were transferred at historical book value. The difference in the consideration paid and the book value of the assets transferred was treated as an adjustment to equity. This transaction had no effect on consolidated shareholders’ equity.
	Reclassifications and Adjustments
	Since the Company accounted for the Merger Transaction as a reverse acquisition and recapitalization, it has retroactively restated Common Stock, Treasury Stock and Paid-in-Capital accounts and earnings per share for periods prior to the Merger Transaction to reflect the historical capitalization of TGI, adjusted for the 1.1330 conversion ratio as discussed in “Note 4 – Merger Transaction”. Certain other reclassifications have also been made to prior years’ financial information to conform to the current year presentation, including the changes in segment presentation discussed in “Note 1 – Nature of Business.”
	The table below reflects the previously reported and revised shareholders’ equity accounts resulting from the Merger Transaction:
		As previously			Revised
	($ in thousands, except per share amounts)	Reported			Amount
	As of December 31, 2012
	Common stock	$	469		$	530
	Treasury stock		(181,435	)		(181,435	)
	Paid-in-capital		780,097			780,036
	For the three-months ended June 30, 2012
	Earnings (Loss) per Share:
	Basic	$	(0.43	)	$	(0.39	)
	Diluted		(0.43	)		(0.39	)
	Weighted average common shares outstanding
	Basic		39,117			43,289
	Diluted		39,117			43,289
	For the six-months ended June 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.06		$	0.05
	Diluted		0.06			0.05
	Weighted average common shares outstanding
	Basic		39,206			43,340
	Diluted		39,268			43,410
	See “Note 15 – Earnings (loss) per Share” for the computation of the earnings per share.
	Accounting Pronouncements
	Accounting guidance adopted in 2012 and 2013
	In July 2012, the Financial Accounting Standards Board (“FASB”) issued amended guidance on testing indefinite-lived intangible assets for impairment. This guidance is intended to reduce the cost and complexity of the annual impairment test by allowing an entity to utilize more qualitative factors and is effective for annual and interim tests performed for fiscal years beginning after September 15, 2012. The Company will consider this guidance in connection with the annual impairment testing of its indefinite-lived intangible assets, which is performed annually in the fourth quarter based on data as of September 30. This guidance does not affect existing guidance on recognition or measurement of impairment losses on indefinite-lived intangible assets, and as such it will not affect the Company’s financial position, results of operations or cash flows.
	In February 2013, the FASB issued amended guidance on the presentation of amounts reclassified out of accumulated other comprehensive income in one place, either on the face of the income statement or in the footnotes to the financial statements. The Company adopted this guidance effective January 1, 2013 on a prospective basis as prescribed by the amended guidance. As all of the information that this guidance requires to be disclosed is already presented elsewhere in the Company’s financial statements under existing GAAP, and it does not affect the classification, recognition or measurement of items within other comprehensive income, the adoption will not affect the Company’s financial position, results of operations or cash flows.
	Accounting guidance not yet effective
	In July 2013, the FASB issued new guidance that permits the use of a new benchmark for hedges. This guidance is effective prospectively for new or re-designated hedges as of July 17, 2013. The Company will consider this guidance if and when it enters into any new hedging relationships.

Merger_Transaction

Merger Transaction	6 Months Ended
	Jun. 30, 2013
Merger Transaction	'
	Note 4 – Merger Transaction
	On August 20, 2012, TGI closed on its previously announced $74.9 million acquisition of a 10.7% stake in Canopius Group Limited (“Canopius Group”), a privately owned Lloyd’s insurance holding company domiciled in Guernsey, Channel Islands. In connection with this acquisition, TGI also entered into an agreement dated April 25, 2012 (the “Master Transaction Agreement”) under which Canopius Group committed to assist TGI with the establishment of a presence at Lloyd’s of London through a special purpose syndicate (“SPS Transaction Right and Acquisition Right”) (subject to required approvals) and granted TGI an option (the “Merger Option”) to combine with Canopius Bermuda. On July 30, 2012, TGI announced that it had exercised the Merger Option and executed an Agreement and Plan of Merger (the “Original Merger Agreement”) with Canopius Bermuda pursuant to which a wholly-owned subsidiary of Canopius Bermuda would acquire all of TGI’s common stock. TGI paid Canopius Group a fee of $1,000,000 to exercise the Merger Option. On November 8, 2012, the Original Merger Agreement was amended by Amendment No. 1 to the Agreement and Plan of Merger to reflect changes to the merger consideration to be received by TGI shareholders (the Original Merger Agreement as so amended, the “Merger Agreement”).
	Prior to the Merger Transaction date, Canopius Group priced on March 6, 2013, a private sale of 100% of the shares of Canopius Bermuda to third party investors for net consideration for $205,862,755. This investment resulted in 14,025,737 shares being issued in the private placement immediately preceding the merger.
	On March 13, 2013, Canopius Bermuda and TGI consummated the Merger Transaction contemplated by the Merger Agreement. Canopius Bermuda was re-named Tower Group International, Ltd. and became the ultimate parent company of TGI, with TGI becoming its indirect wholly-owned subsidiary. Pursuant to the terms of the Merger Agreement, among other things, (i) 100% of the issued and outstanding shares of TGI common stock was cancelled and automatically converted into the right to receive 1.1330 common shares of the Company, par value $0.01 per share (the “ Common Shares”), (ii) each outstanding option to acquire TGI common stock, whether vested or unvested and whether granted under TGI’s 2008 Long-Term Equity Compensation Plan or otherwise, automatically vested, free of any forfeiture conditions, and constituted a fully vested option to acquire that number of Common Shares (rounded down to the nearest whole number) equal to the number of shares of TGI common stock subject to such option multiplied by 1.1330, on the same terms and conditions (other than vesting and performance conditions) as were applicable to such TGI stock option immediately prior to the Merger Transaction, with the exercise price of such option adjusted to be the original exercise price divided by 1.1330, and (iii) substantially all issued and outstanding shares of TGI restricted stock, whether granted under TGI’s 2008 Long-Term Equity Compensation Plan or otherwise, automatically vested, free of any forfeiture conditions, and was converted into the right to receive, as soon as reasonably practicable after the effective time, 1.1330 Common Shares.
	Immediately after giving effect to the issuance of Common Shares to the former TGI shareholders in the Merger Transaction, approximately 57,432,150 Common Shares were outstanding, of which 76% were held by the former TGI shareholders. The remaining 24% of Common Shares outstanding immediately after giving effect to the Merger Transaction were held by third party investors. As the Company is the successor issuer to TGI, succeeding to the attributes of TGI as registrant, including TGI’s SEC filer code, its Common Shares trade on the same exchange, the NASDAQ Global Select Market, and under the same trading symbol, “TWGP,” that the shares of TGI common stock traded on and under prior to the Merger Transaction.
	The Merger Transaction is expected to advance the Company’s strategy and create a more efficient global, diversified specialty insurance company consisting of commercial, specialty and personal lines, reinsurance and international specialty products. In addition, the establishment of a Bermuda domicile provides the Company with an international platform through which it accesses the U.S., Bermuda and the Lloyd’s of London (“Lloyd’s”) markets.
	Accounting for the Merger Transaction
	The Company has accounted for the Merger Transaction as a reverse acquisition in which TGI, the legal acquiree, was identified and treated as the accounting acquirer and Tower Group International, Ltd., the legal acquirer, was identified and treated as the accounting acquiree. The identification of the accounting acquirer and acquiree in the Merger Transaction was primarily based on the fact that immediately following the close of the Merger Transaction there was a change in control of the Company with TGI designees to the Company’s Board of Directors comprising all of its directors and TGI’s former senior management comprising the Company’s entire senior management team. In accordance with accounting guidance for reverse acquisitions, the unaudited consolidated financial statements of the Company following the Merger Transaction have been issued under the name of the Company, as the legal parent, but reflect a continuation of the financial statements of TGI, as the accounting acquirer, with one exception, which was the retroactive adjustment of TGI’s historical legal capital to reflect the transaction as a recapitalization of TGI’s historical capital accounts. On the effective date of the Merger Transaction, the assets and liabilities of Tower Group International, Ltd. were accounted for under the acquisition method, under which they have been reflected at their respective acquisition date fair values.
	Prior to the Merger Transaction, Canopius Bermuda restructured its insurance operations as contemplated in the Master Transaction Agreement. This restructuring occurred primarily through the execution of retrocession agreements with Canopius Reinsurance Limited (“CRL”), an indirectly wholly-owned subsidiary of Canopius Group, to retrocede a percentage of Lloyd’s of London Syndicate 4444 (“Syndicate 4444”) business for the Year of Account (“YOA”) 2012, YOA 2011 and prior years, which Canopius Bermuda assumed from Canopius Group. Syndicate 4444 is an insurance syndicate managed by Canopius Group. The Company accounts for these retrocession agreements in accordance with prospective accounting treatment, and reports the assumed and ceded assets and liabilities on a gross basis on the consolidated balance sheet. On September 30, 2013, Tower commuted the Syndicate 4444 YOA 2012 and YOA 2011 and prior years retrocession agreements with CRL and novated the assumed reinsurance with Canopius Group on these same contracts.
	In addition, effective January 1, 2013, pursuant to the terms of the Master Transaction Agreement, prior to the Merger Transaction, TGI entered into a commutation agreement whereby the TGI commuted Syndicate 4444 YOA 2012 and YOA 2011 business TGI previously reinsured from Canopius Group in prior years. There was no gain or loss recognized on this commutation.
	The following provides details of the purchase consideration, the fair values of the respective assets acquired and liabilities assumed and the resulting amount of goodwill recorded in connection with the Merger Transaction.
	The purchase consideration was determined based on the total consideration received by Canopius Group for its sale of 100% of its equity ownership of Canopius Bermuda, and the proceeds received for the issuance and exercise of the Merger Option from TGI.
	(in thousands)
	Consideration received by Canopius Group from the third party sale	$	205,863
	Fair value of Merger Option received in connection with TGI’s investment in Canopius Group		484
	Exercise price of Merger Right received from TGI upon exercise		1,000
	Total preliminary purchase consideration	$	207,347
	($ in thousands)
	Assets
	Cash and cash equivalents	$	134,741
	Investments		26,485
	Reinsurance recoverables		468,727
	Prepaid reinsurance		152,431
	Funds held by reinsured companies		698,819
	Other assets		75,219
	Liabilities
	Loss and loss adjustment expenses		630,613
	Unearned premiums		169,963
	Funds held under reinsurance agreements		560,714
	Other liabilities		15,916
	Net assets acquired	$	179,216
	Purchase Consideration		207,347
	Goodwill	$	28,131
	Direct costs of the acquisition were expensed as incurred. During the three and six months ended June 30, 2013, the Company recognized approximately $0.7 million and $19.7 million, respectively, of such costs, all of which have been classified within “acquisition-related transaction costs” on the consolidated statement of operations. Such costs for the six months ended June 30, 2013 included $11.6 million in compensation expense (of which accelerated vesting of restricted stock was $10.3 million) and $8.1 million in legal and accounting fees.
	The resulting goodwill recognized in connection with the Merger Transaction is mainly derived from the synergies and economies of scale expected to result from the combined operations of the Company. See “Note 5 – Goodwill and Intangible Assets” for the allocation of the Merger Transaction goodwill by segment.
	The fair value of loss and loss adjustment expenses includes $19.1 million of reserves for risk premiums (“risk premiums”). The risk premium was determined using a cash flow model. This model used an estimate of net nominal future cash flows related to liabilities for losses and loss adjustment expenses that a market participant would expect as of the date of the transaction. These future cash flows were adjusted for the time value of money at a risk free rate and a risk margin to compensate an acquirer for bearing the risk associated with the liabilities.
	Since the effective date of the Merger Transaction on March 13, 2013 through June 30, 2013, the operations of the acquired business accounted for approximately $40.8 million and $(22.0) million of the Company’s consolidated revenues and net income (loss), respectively.
	The following unaudited pro forma financial information presents the consolidated revenues and net income (loss) of the Company for the three and six months ended June 30, 2013 and 2012, as if the Merger Transaction had been completed as of January 1, 2012.
	These pro forma amounts exclude any pro forma impacts to the Company’s effective federal income tax rates.
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Revenues	$	460,518		$	509,666		$	940,145		$	979,033
	Net Income (Loss)		(505,876	)		(16,887	)		(485,248	)		10,074

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2013
Goodwill and Intangible Assets	'
	Note 5–Goodwill and Intangible Assets
	Goodwill is calculated as the excess of purchase price over the net fair value of assets acquired. Under GAAP, the Company is required to allocate goodwill to each of its reporting units. On March 13, 2013, the Company recorded $28.1 million of goodwill in connection with the Merger Transaction (See “Note 4– Merger Transaction”), which was mainly derived from synergies and economies of scale expected to result from the combined operations of the Company. Management allocated the goodwill recognized in the Merger Transaction to the Commercial Insurance reporting unit.
	2013 Reorganization
	In the second quarter of 2013, the Company changed the way it presents its results by segment, as described in “Note 1 – Nature of Business”. Following the reorganization, based on information regularly reviewed by the Company’s chief operating decision maker, the Company concluded it had three reporting units corresponding to it each of the business segments: (i) Commercial Insurance, (ii) Specialty Insurance and Reinsurance and (iii) Personal Insurance.
	In accordance with GAAP, when an entity reorganizes its reporting structure in a manner that changes the composition of one or more of its reporting units, the entity reassigns goodwill to the affected reporting units by using a relative fair value allocation approach.
	Goodwill Impairment Testing and Charge
	The Company tests goodwill balances for impairment annually in the fourth quarter of each year using a September 30 measurement date, or more frequently if circumstances indicate that the value of goodwill may be impaired. Goodwill impairment is performed at the reporting unit level and the test requires a two-step process. In performing Step 1of the impairment test, management compared the estimated fair values of the applicable reporting units to their aggregate carrying values, including goodwill. If the carrying amount of a reporting unit including goodwill were to exceed the fair value of the reporting unit, Step 2 of the goodwill impairment would be performed. Step 2 of the goodwill impairment test requires comparing the implied fair value of the affected reporting unit’s goodwill against the carrying value of that goodwill.
	In its 2012 annual impairment test, management determined that a greater risk of future impairment existed for the Commercial Insurance reporting unit. During the second quarter of 2013, management concluded an impairment test was required as a result of the significant prior years’ loss reserves incurred (see “Note 9 – Loss and Loss Adjustment Expense”) and the 2013 reorganization.
	In conducting the goodwill impairment analysis as of June 30, 2013, the Company tested the reporting units prior to the reorganization as required by GAAP. The Company estimated each of the reporting units’ fair values using a market multiple approach based on tangible book values. Historically, the Company also utilized market multiple approaches based on (i) book value, (ii) estimates of projected results for future periods, and (iii) a valuation technique using discounted cash flows. However, based upon the significance of the loss reserve charge recorded in the second quarter of 2013, the reduction to Tower’s insurance subsidiaries’ capital and surplus levels (see “Note 16 – Statutory Financial Information”), management in its judgment concluded a multiple of tangible book value was most indicative of a price a market participant would pay for the reporting units. In addition, the Commercial Insurance reporting unit’s estimated fair value was adjusted for the expected capital infusion a market participant would be expected to fund into the insurance businesses to maintain historical rating agency ratings.
	Step 1 of the impairment test indicated the Commercial Insurance unit’s carrying value exceeded its fair value and the Personal Insurance unit’s fair value exceeded its carrying value.
	Accordingly, the Company performed a Step 2 impairment test on the Commercial Insurance reporting unit. Based on the results, the Company recorded a non-cash goodwill impairment charge of $214.0 million to write-down all of the goodwill in the Commercial Insurance reporting unit as of June 30, 2013.
	The following table reflects the changes to goodwill during 2013 and is presented using the reporting units prior to the reorganization.
	($ in thousands)	Commercial			Personal		Total
		Insurance			Insurance
	Balance, January 1, 2013	$	185,918		$	55,540	$	241,458
	Goodwill from Merger Transaction		28,131			-		28,131
	Goodwill impairment		(214,049	)		-		(214,049	)
	Total, June 30, 2013	$	-		$	55,540	$	55,540
	As of June 30, 2013, all remaining goodwill is in the Personal Insurance reporting unit. Subsequent goodwill assessments could result in personal lines goodwill impairment due to the impact of a volatile financial impact on earnings, changes in liquidity and market capitalizations, or other unfavorable events resulting rating agency downgrades.
	Intangible Assets
	The intangible assets consist of finite life and indefinite life assets. Finite life intangible assets include customer relationships and trademarks. Insurance company licenses and management contracts are considered indefinite life intangible assets subject to annual impairment testing. Management assessed the carrying value of its intangible assets as of June 30, 2013, and concluded an impairment charge of $3.8 million was required to reduce its customer relationship intangible assets. This charge is reported in Other Operating Expenses in the consolidated statements of operations.

Variable_Interest_Entities_VIE

Variable Interest Entities ("VIEs")	6 Months Ended
	Jun. 30, 2013
Variable Interest Entities ("VIEs")	'
	Note 6–Variable Interest Entities (“VIEs”)
	Through its management companies, Tower is the attorney-in-fact for the Reciprocal Exchanges and has the ability to direct their activities. The Reciprocal Exchanges are policyholder-owned insurance carriers organized as unincorporated associations. Each policyholder insured by the Reciprocal Exchanges shares risk with the other policyholders.
	In the event of dissolution, policyholders would share any residual unassigned surplus in the same proportion as the amount of insurance purchased but are not subject to assessment for any deficit in unassigned surplus of the Reciprocal Exchanges. Tower receives management fee income for the services provided to the Reciprocal Exchanges. The assets of the Reciprocal Exchanges can be used only to settle the obligations of the Reciprocal Exchanges and general creditors to their liabilities have no recourse to Tower as the primary beneficiary.
	In addition, Tower holds the surplus notes issued by the Reciprocal Exchanges when they were originally capitalized. The obligation to repay principal and interest on the surplus notes is subordinated to the Reciprocal Exchanges’ other liabilities including obligations to policyholders and claimants for benefits under insurance policies. Principal and interest on the surplus notes are payable only with regulatory approval. The Company has no ownership interest in the Reciprocal Exchanges.
	The Company determined that each of the Reciprocal Exchanges qualifies as a VIE and that the Company is the primary beneficiary as it has both the power to direct the activities of the Reciprocal Exchanges that most significantly impact their economic performance and the risk of economic loss through its ownership of the surplus notes. Accordingly, the Company consolidates these Reciprocal Exchanges and eliminates all intercompany balances and transactions with Tower.
	For the three months ended June 30, 2013, the Reciprocal Exchanges recognized total revenues, total expenses and net income (loss) of $49.1 million, $48.3 million and $0.8 million, respectively. For the three months ended June 30, 2012, the Reciprocal Exchanges recognized total revenues, total expenses and net income of $49.2 million, $48.8 million and $0.4 million, respectively.
	For the six months ended June 30, 2013, the Reciprocal Exchanges recognized total revenues, total expenses and net income (loss) of $96.4 million, $106.9 million and $(10.5) million, respectively. For the six months ended June 30, 2012, the Reciprocal Exchanges recognized total revenues, total expenses and net income of $99.4 million, $96.0 million and $3.4 million, respectively.

Investments

Investments	6 Months Ended
	Jun. 30, 2013
Investments	'
	Note 7—Investments
	The cost or amortized cost and fair value of the Company’s investments in fixed maturity and equity securities, gross unrealized gains and losses, and other-than-temporary impairment losses (“OTTI”) as of June 30, 2013 and December 31, 2012 are summarized as follows:
	($ in thousands)	Cost or			Gross			Gross			Fair Value			Unrealized
		Amortized			Unrealized			Unrealized						OTTI
		Cost			Gains			Losses						Losses (1)
	June 30, 2013
	U.S. Treasury securities	$	390,003		$	1,024		$	(5,780	)	$	385,247		$	-
	U.S. Agency securities		104,099			2,189			(965	)		105,323			-
	Municipal bonds		568,991			24,132			(5,732	)		587,391			(71	)
	Corporate and other bonds
	Finance		246,779			14,594			(4,240	)		257,133			-
	Industrial		406,976			13,171			(5,675	)		414,472			-
	Utilities		58,368			2,078			(2,152	)		58,294			(203	)
	Commercial mortgage-backed securities		217,531			21,439			(2,351	)		236,619			(604	)
	Residential mortgage-backed securities
	Agency backed securities		161,783			4,891			(1,614	)		165,060			-
	Non-agency backed securities		35,583			4,059			(30	)		39,612			(6	)
	Asset-backed securities		39,294			1,102			(2	)		40,394			-
	Total fixed-maturity securities		2,229,407			88,679			(28,541	)		2,289,545			(884	)
	Preferred stocks, principally financial sector		21,584			188			(1,137	)		20,635			-
	Common stocks, principally financial and industrial sectors		108,765			8,463			(463	)		116,765			-
	Short-term investments		13,415			-			(36	)		13,379			-
	Total, June 30, 2013	$	2,373,171		$	97,330		$	(30,177	)	$	2,440,324		$	(884	)
	Tower	$	2,121,665		$	87,920		$	(25,786	)	$	2,183,799		$	(884	)
	Reciprocal Exchanges		251,506			9,410			(4,391	)		256,525			-
	Total, June 30, 2013	$	2,373,171		$	97,330		$	(30,177	)	$	2,440,324		$	(884	)
	December 31, 2012, as restated
	U.S. Treasury securities	$	183,462		$	1,500		$	(13	)	$	184,949		$	-
	U.S. Agency securities		98,502			4,351			(76	)		102,777			-
	Municipal bonds		633,373			52,914			(244	)		686,043			-
	Corporate and other bonds
	Finance		233,849			21,293			(1,095	)		254,047			-
	Industrial		412,465			26,556			(868	)		438,153			-
	Utilities		51,698			2,958			(191	)		54,465			-
	Commercial mortgage-backed securities		211,819			30,375			(141	)		242,053			-
	Residential mortgage-backed securities
	Agency backed securities		283,652			12,326			(262	)		295,716			-
	Non-agency backed securities		38,615			3,575			(34	)		42,156			(6	)
	Asset-backed securities		42,751			1,615			(14	)		44,352			-
	Total fixed-maturity securities		2,190,186			157,463			(2,938	)		2,344,711			(6	)
	Preferred stocks, principally financial sector		31,272			730			(481	)		31,521			-
	Common stocks, principally industrial and financial sectors		118,076			953			(4,292	)		114,737			-
	Short-term investments		4,749			1			-			4,750			-
	Total, December 31, 2012, as restated	$	2,344,283		$	159,147		$	(7,711	)	$	2,495,719		$	(6	)
	Tower	$	2,075,189		$	141,614		$	(7,210	)	$	2,209,593		$	(6	)
	Reciprocal Exchanges		269,094			17,533			(501	)		286,126			-
	Total, December 31, 2012, as restated	$	2,344,283		$	159,147		$	(7,711	)	$	2,495,719		$	(6	)
	(1) Represents the gross unrealized loss on other-than-temporarily impaired securities recognized in accumulated other comprehensive income (loss).
	In accordance with Lloyd’s operating guidelines, the Company deposits funds at Lloyd’s to support underwriting operations. These funds are available only to fund claims obligations. These restricted assets consisted of approximately $32 million of cash and cash equivalents as of June 30, 2013. In addition, the Company had $457.3 million and $481.5 million of cash and cash equivalents and investments as of June 30, 2013 and December 31, 2012, respectively, held by counterparties as collateral or in trusts to support letters of credit issued on the Company’s behalf, reinsurance liabilities on certain assumed reinsurance treaties, collateral posted for certain leases and other purposes.
	The Company also deposits funds with various state and governmental authorities in the U.S. For a discussion of the Company’s deposits with state and governmental authorities, see “Note 7– Investments” of the Notes to Consolidated Financial Statements in TGI’s Amendment No. 2 to its Annual Report on Form 10-K for the year ended December 31, 2012.
	Major categories of net investment income are summarized as follows:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Income
	Fixed-maturity securities	$	20,562		$	24,511		$	41,535		$	49,924
	Equity securities		6,808			6,603			13,292			14,239
	Cash and cash equivalents		19			505			70			798
	Other invested assets		2,158			1,313			6,414			3,146
	Other		287			203			615			349
	Total		29,834			33,135			61,926			68,456
	Expenses
	Investment expenses		(1,432	)		(1,354	)		(3,207	)		(2,732	)
Net investment income	$	28,402		$	31,781		$	58,719		$	65,724
Tower		27,612			30,267			57,195			62,525
Reciprocal Exchanges		2,458			3,177			4,839			6,526
Elimination of interest on Reciprocal Exchange surplus notes		(1,668	)		(1,663	)		(3,315	)		(3,327	)
Net investment income	$	28,402		$	31,781		$	58,719		$	65,724
Proceeds from the sale of fixed-maturity securities were $759.0 million and $980.0 million for the six months ended June 30, 2013 and 2012, respectively. Proceeds from the sale of equity securities were $796.8 million and $745.6 million for the six months ended June 30, 2013 and 2012, respectively.
Gross realized gains, losses and impairment write-downs on investments are summarized as follows:
	Three Months Ended						Six Months Ended
	June 30,						June 30,
($ in thousands)	2013			2012			2013			2012
Fixed-maturity securities
Gross realized gains	$	10,479		$	12,354		$	17,843		$	25,162
Gross realized losses		(1,672	)		(609	)		(1,862	)		(2,551	)
		8,807			11,745			15,981			22,611
Equity securities
Gross realized gains		5,323			2,685			9,559			4,179
Gross realized losses		(12,717	)		(9,808	)		(17,530	)		(16,160	)
		(7,394	)		(7,123	)		(7,971	)		(11,981	)
Other
Gross realized gains		2,100			555			3,855			1,790
Gross realized losses		(1,091	)		(3,174	)		(1,903	)		(4,113	)
		1,009			(2,619	)		1,952			(2,323	)
Net realized gains (losses) on investments		2,422			2,003			9,962			8,307
Other-than-temporary impairment losses:
Fixed-maturity securities		(23	)		(765	)		(187	)		(882	)
Equity securities		(4,433	)		(1,219	)		(4,958	)		(4,078	)
Total other-than-temporary impairment losses recognized in earnings		(4,456	)		(1,984	)		(5,145	)		(4,960	)
Total net realized investment gains (losses)	$	(2,034	)	$	19		$	4,817		$	3,347
Tower	$	(2,243	)	$	(110	)	$	3,990		$	1,028
Reciprocal Exchanges		209			129			827			2,319
Total net realized investment gains (losses)	$	(2,034	)	$	19		$	4,817		$	3,347
Management may dispose of a particular security due to changes in facts and circumstances related to the invested asset that have arisen since the last analysis supporting management’s determination whether or not it intended to sell the security, and if not, whether it is more likely than not that the Company would be required to sell the security before recovery of its amortized cost basis.
Impairment Review
Management regularly reviews the Company’s fixed-maturity and equity security portfolios in accordance with its impairment policy to evaluate the necessity of recording impairment losses for OTTI. The determination of OTTI is a subjective process and different judgments and assumptions could affect the timing of loss realization.
Management, in conjunction with its outside portfolio managers, analyzes its non-agency residential mortgage-backed securities (“RMBS”) using default loss models based on the performance of the underlying loans. Performance metrics include delinquencies, defaults, foreclosures, anticipated cash flow prepayments and cumulative losses incurred. The expected losses for a mortgage pool are compared to the break-even loss, which represents the point at which the Company’s tranche begins to experience losses.
The commercial mortgage-backed securities (“CMBS”) holdings are evaluated using analytical techniques and various metrics including the level of subordination, debt-service-coverage ratios, loan-to-value ratios, delinquencies, defaults and foreclosures.
For the non-structured fixed-maturity securities (U.S. Treasury and Agency securities, municipal bonds, and corporate debt), unrealized losses are reviewed to determine whether full recovery of principal and interest will be received. The estimate of expected cash flows is determined by projecting a recovery value and a recovery time frame and assessing whether further principal and interest will be received. The determination of recovery value incorporates an issuer valuation assumption utilizing one or a combination of valuation methods as deemed appropriate by management. The present value of the cash flows is determined by applying the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment) and an estimated recovery time frame. For securities for which the issuer is financially troubled but not in bankruptcy, that time frame is generally longer. Included in the present value calculation are expected principal and interest payments; however, for securities for which the issuer is classified as bankrupt or in default, the present value calculation assumes no interest payments and a single recovery amount. In situations for which a present value of cash flows cannot be estimated, a write-down to fair value is recorded.
In estimating the recovery value, significant judgment is involved in the development of assumptions relating to a number of factors related to the issuer including, but not limited to, revenue, margin and earnings projections, the likely market or liquidation values of assets, potential additional debt to be incurred pre- or post- bankruptcy/restructuring, the ability to shift existing or new debt to different priority layers, the amount of restructuring/bankruptcy expenses, the size and priority of unfunded pension obligations, litigation or other contingent claims, the treatment of intercompany claims and the likely outcome with respect to inter-creditor conflicts.
The evaluation of equity securities includes management’s intent and ability to hold the security to recovery. Management will record OTTI in those situations where it does not intend to hold the security to recovery or if the security is not expected to recover in value in the near term.
The following table shows the fixed-maturity and equity securities OTTI amounts for the three and six months ended June 30, 2013 and 2012:
	Three Months Ended						Six Months Ended
	June 30,						June 30,
($ in thousands)	2013			2012			2013			2012
Corporate and other bonds	$	-		$	(648	)	$	-		$	(737	)
Commercial mortgage-backed securities		(23	)		(403	)		(47	)		(403	)
Residential mortgage-backed securities		(140	)		-			(140	)		(28	)
Equities		(4,293	)		(1,219	)		(4,958	)		(4,078	)
Other-than-temporary-impairments		(4,456	)		(2,270	)		(5,145	)		(5,246	)
Portion of loss recognized in accumulated other comprehensive income (loss)		-			286			-			286
Impairment losses recognized in earnings	$	(4,456	)	$	(1,984	)	$	(5,145	)	$	(4,960	)
Tower	$	(4,456	)	$	(1,984	)	$	(5,145	)	$	(4,960	)
Reciprocal Exchanges		-			-			-			-
Impairment losses recognized in earnings	$	(4,456	)	$	(1,984	)	$	(5,145	)	$	(4,960	)
The following table provides a rollforward of the cumulative amounts of credit OTTI for securities still held showing the amounts that have been included in earnings on a pretax basis for the three months ended June 30, 2013 and 2012:
	Three Months Ended
	June 30,
($ in thousands)	2013			2012
Balance, April 1,	$	4,516		$	6,084
Additional credit losses recognized during the period, related to securities for which:
No OTTI has been previously recognized		23			765
OTTI has been previously recognized		-			-
Reductions due to:
Securities sold during the period (realized)		-			(730	)
Balance, June 30,	$	4,539		$	6,119
The following table provides a rollforward of the cumulative amounts of credit OTTI for securities still held showing the amounts that have been included in earnings on a pretax basis for the six months ended June 30, 2013 and 2012:
	Six Months Ended
	June 30,
($ in thousands)	2013			2012
Balance, January 1,	$	4,492		$	12,666
Additional credit losses recognized during the period, related to securities for which:
No OTTI has been previously recognized		47			854
OTTI has been previously recognized		-			28
Reductions due to:
Securities sold during the period (realized)		-			(7,429	)
Balance, June 30,	$	4,539		$	6,119
Unrealized Losses
There are 668 securities at June 30, 2013, including fixed maturities and equity securities, which account for the gross unrealized loss, none of which is deemed by management to be OTTI. Temporary losses on corporate and other bonds result from purchases made in a lower yield spread environment. In addition, there have been some ratings downgrades on certain of these securities. After analyzing the credit quality, balance sheet strength and company outlook, management believes these securities will recover in value. To the extent projected cash flows on structured securities change adversely, they would be considered OTTI, and an impairment loss would be recognized in the current period. Management considered all relevant factors, including expected recoverability of cash flows, in assessing whether a loss was other-than-temporary. The Company does not intend to sell these fixed maturity securities, and it is not more likely than not that these securities will be sold before recovering their cost basis.
For all fixed-maturity securities in an unrealized loss position at June 30, 2013, the Company has received all contractual interest payments (and principal if applicable). Based on the continuing receipt of cash flow and the foregoing analyses, management expects continued timely payments of principal and interest and considers the losses to be temporary.
The unrealized loss position associated with the fixed-maturity portfolio was $28.5 million as of June 30, 2013, consisting primarily of corporate bonds and mortgage-backed securities of $16.1 million. The total fixed-maturity portfolio of gross unrealized losses included 644 securities which were, in aggregate, approximately 3.0% below amortized cost. Of the 644 fixed maturity investments identified, 27 have been in an unrealized loss position for more than 12 months. The total unrealized loss on these investments at June 30, 2013 was $0.10 million. Management does not consider these investments to be other-than-temporarily impaired.
For common stocks, there were 17 securities in a loss position at June 30, 2013 totaling $0.5 million. Management evaluated the financial condition of the common stock issuers, the severity and duration of the impairment, and the Company’s ability and intent to hold to recovery. The evaluation consisted of a detailed review, including but not limited to some or all of the following factors for each security: the current S&P rating, analysts’ reports, past earnings trends and analysts’ earnings expectations for the next 12 months, liquidity, near-term financing risk, and whether the company was currently paying dividends on its equity securities. Management does not consider these investments to be other-than-temporarily impaired.
The following table presents information regarding invested assets that were in an unrealized loss position at June 30, 2013 and December 31, 2012 by amount of time in a continuous unrealized loss position:
	Less than 12 Months						12 Months or Longer						Total
	Fair			Unrealized			Fair			Unrealized			Aggregate			Unrealized
($ in thousands)	Value			Losses			Value			Losses			Fair Value			Losses
June 30, 2013
U.S. Treasury securities	$	318,415		$	(5,780	)	$	-		$	-		$	318,415		$	(5,780	)
U.S. Agency securities		32,802			(965	)		-			-			32,802			(965	)
Municipal bonds		151,394			(5,688	)		218			(44	)		151,612			(5,732	)
Corporate and other bonds
Finance		76,192			(4,240	)		-			-			76,192			(4,240	)
Industrial		188,193			(5,635	)		1,184			(40	)		189,377			(5,675	)
Utilities		42,328			(2,152	)		-			-			42,328			(2,152	)
Commercial mortgage-backed securities		50,984			(2,351	)		-			-			50,984			(2,351	)
Residential mortgage-backed securities
Agency backed		54,462			(1,613	)		229			(1	)		54,691			(1,614	)
Non-agency backed		639			(16	)		199			(14	)		838			(30	)
Asset-backed securities		2,507			(2	)		-			-			2,507			(2	)
Total fixed-maturity securities		917,916			(28,442	)		1,830			(99	)		919,746			(28,541	)
Preferred stocks		9,802			(821	)		6,089			(316	)		15,891			(1,137	)
Common stocks		44,338			(463	)		-			-			44,338			(463	)
Short-term investments		11,379			(36	)		-			-			11,379			(36	)
Total, June 30, 2013	$	983,435		$	(29,762	)	$	7,919		$	(415	)	$	991,354		$	(30,177	)
Tower	$	875,960		$	(25,386	)	$	7,553		$	(400	)	$	883,513		$	(25,786	)
Reciprocal Exchanges		107,475			(4,376	)		366			(15	)		107,841			(4,391	)
Total, June 30, 2013	$	983,435		$	(29,762	)	$	7,919		$	(415	)	$	991,354		$	(30,177	)
December 31, 2012, as restated
U.S. Treasury securities	$	44,347		$	(13	)	$	-		$	-		$	44,347		$	(13	)
U.S. Agency securities		22,345			(76	)		-			-			22,345			(76	)
Municipal bonds		21,532			(235	)		251			(9	)		21,783			(244	)
Corporate and other bonds
Finance		16,853			(1,095	)		-			-			16,853			(1,095	)
Industrial		53,576			(666	)		4,188			(202	)		57,764			(868	)
Utilities		20,143			(191	)		7			-			20,150			(191	)
Commercial mortgage-backed securities		23,223			(141	)		95			-			23,318			(141	)
Residential mortgage-backed securities
Agency backed		59,009			(261	)		25			(1	)		59,034			(262	)
Non-agency backed		815			(6	)		588			(28	)		1,403			(34	)
Asset-backed securities		1,499			(3	)		4,232			(11	)		5,731			(14	)
Total fixed-maturity securities		263,342			(2,687	)		9,386			(251	)		272,728			(2,938	)
Preferred stocks		9,716			(155	)		5,724			(326	)		15,440			(481	)
Common stocks		55,560			(4,292	)		-			-			55,560			(4,292	)
Total, December 31, 2012, as restated	$	328,618		$	(7,134	)	$	15,110		$	(577	)	$	343,728		$	(7,711	)
Tower	$	270,609		$	(6,732	)	$	13,338		$	(478	)	$	283,947		$	(7,210	)
Reciprocal Exchanges		58,009			(402	)		1,772			(99	)		59,781			(501	)
Total, December 31, 2012, as restated	$	328,618		$	(7,134	)	$	15,110		$	(577	)	$	343,728		$	(7,711	)
Management evaluated the severity of the impairment in relation to the carrying values for the securities referred to above and considered all relevant factors in assessing whether the loss was other-than-temporary. Management does not intend to sell its fixed-maturity securities, and it is not more likely than not that fixed maturity and equity securities will be sold until there is a recovery of fair value to the original cost basis; which may be at maturity for the fixed income securities.
Fixed-Maturity Investment—Time to Maturity
The following table shows the amortized cost and fair value of the fixed-maturity portfolio by contractual time to maturity at June 30, 2013 and December 31, 2012:
	Tower						Reciprocal Exchanges						Total
($ in thousands)	Amortized			Fair Value			Amortized			Fair			Amortized			Fair Value
	Cost						Cost			Value			Cost
June 30, 2013
Remaining Time to Maturity
Less than one year	$	38,967		$	39,597		$	3,996		$	4,148		$	42,963		$	43,745
One to five years		614,572			626,489			41,860			43,790			656,432			670,279
Five to ten years		646,016			654,732			66,201			65,527			712,217			720,259
More than 10 years		301,473			310,890			62,131			62,685			363,604			373,575
Mortgage and asset-backed securities		379,624			404,062			74,567			77,625			454,191			481,687
Total, June 30, 2013	$	1,980,652		$	2,035,770		$	248,755		$	253,775		$	2,229,407		$	2,289,545
December 31, 2012, as restated
Remaining Time to Maturity
Less than one year	$	30,082		$	30,614		$	2,678		$	2,715		$	32,760		$	33,329
One to five years		489,939			510,523			45,576			47,275			535,515			557,798
Five to ten years		564,556			607,711			76,480			80,009			641,036			687,720
More than 10 years		346,410			379,045			57,628			62,542			404,038			441,587
Mortgage and asset-backed securities		495,249			536,255			81,588			88,022			576,837			624,277
Total, December 31, 2012, as restated	$	1,926,236		$	2,064,148		$	263,950		$	280,563		$	2,190,186		$	2,344,711
Other Invested Assets
The following table shows the composition of the other invested assets as of June 30, 2013 and December 31, 2012:
	June 30,			December 31,
($ in thousands)	2013			2012
Limited partnerships, equity method	$	34,843		$	23,864
Real estate, amortized cost		7,645			7,422
Securities reported under the fair value option		30,250			25,000
Other		4,300			1,500
Total	$	77,038		$	57,786
Securities reported under the fair value option include five securities for which the Company has elected the fair value option. This election was made to simplify the accounting for these instruments which contain embedded derivatives and other features.
The fair value of the limited partnerships in the table above approximates their carrying value under the equity method of accounting. The significant inputs used to determine fair value of these limited partnerships are considered Level 3 pursuant to the fair value hierarchy. See “Note 8 – Fair Value Measurements” below. As of June 30, 2013, the Company had future funding commitments of $47.0 million to these limited partnerships.

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2013
Fair Value Measurements	'
	Note 8—Fair Value Measurements
	GAAP establishes a three-level hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). If the inputs used to measure the assets or liabilities fall within different levels of the hierarchy, the classification is based on the lowest level input that is significant to the fair value measurement of the asset or liability. Classification of assets and liabilities within the hierarchy considers the markets in which the assets and liabilities are traded, including during periods of market disruption, and the reliability and transparency of the assumptions used to determine fair value. The hierarchy requires the use of observable market data when available. The levels of the hierarchy are as follows:
	Level 1 — Inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities traded in active markets. Included are those equity securities that are traded on active exchanges, such as the NASDAQ Global Select Market.
	Level 2 — Inputs to the valuation methodology include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability and market-corroborated inputs. Included are investments in U.S. Treasury and Agency securities and, together with municipal bonds, corporate debt securities, commercial mortgages, residential mortgage-backed securities and asset-backed securities. Additionally, interest-rate swap contracts utilize Level 2 inputs in deriving fair values.
	Level 3 — Inputs to the valuation methodology are unobservable in the market for the asset or liability and are significant to the fair value measurement. Material assumptions and factors considered in pricing investment securities may include projected cash flows, collateral performance including delinquencies, defaults and recoveries, and any market clearing activity or liquidity circumstances in the security or similar securities that may have occurred since the prior pricing period.
	The availability of observable inputs varies and is affected by a wide variety of factors. When the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires significantly more judgment. The degree of judgment exercised by management in determining fair value is greatest for investments categorized as Level 3. For investments in this category, management considers prices and inputs that are current as of the measurement date. In periods of market dislocation, as characterized by current market conditions, the ability to observe stable prices and inputs may be reduced for many instruments. This condition could cause a security to be reclassified between levels.
	As at June 30, 2013 and December 31, 2012, the Company’s financial instruments carried at fair value are allocated among levels as follows:
	($ in thousands)	Level 1		Level 2			Level 3		Total
	June 30, 2013
	Fixed-maturity securities
	U.S. Treasury securities	$	-	$	385,247		$	-	$	385,247
	U.S. Agency securities		-		105,323			-		105,323
	Municipal bonds		-		587,391			-		587,391
	Corporate and other bonds		-		729,899			-		729,899
	Commercial mortgage-backed securities		-		236,619			-		236,619
	Residential mortgage-backed securities
	Agency		-		165,060			-		165,060
	Non-agency		-		39,612			-		39,612
	Asset-backed securities		-		40,394			-		40,394
	Total fixed-maturities		-		2,289,545			-		2,289,545
	Equity securities		137,400		-			-		137,400
	Short-term investments		-		13,379			-		13,379
	Total investments at fair value		137,400		2,302,924			-		2,440,324
	Other invested assets (1)		-		-			30,250		30,250
	Other liabilities									-
	Interest rate swap contracts		-		(6,830	)		-		(6,830	)
	Debt and equity securities sold, not yet purchased		-		(25,570	)		-		(25,570	)
	Total, June 30, 2013	$	137,400	$	2,270,524		$	30,250	$	2,438,174
	Tower	$	134,650	$	2,016,748		$	30,250	$	2,181,648
	Reciprocal Exchanges		2,750		253,776			-		256,526
	Total, June 30, 2013	$	137,400	$	2,270,524		$	30,250	$	2,438,174
	December 31, 2012, as restated
	Fixed-maturity securities
	U.S. Treasury securities	$	-	$	184,949		$	-	$	184,949
	U.S. Agency securities		-		102,777			-		102,777
	Municipal bonds		-		686,043			-		686,043
	Corporate and other bonds		-		746,665			-		746,665
	Commercial mortgage-backed securities		-		242,053			-		242,053
	Residential mortgage-backed securities
	Agency		-		295,716			-		295,716
	Non-agency		-		42,156			-		42,156
	Asset-backed securities		-		44,352			-		44,352
	Total fixed-maturities		-		2,344,711			-		2,344,711
	Equity securities		146,258		-			-		146,258
	Short-term investments		-		4,750			-		4,750
	Total investments at fair value		146,258		2,349,461			-		2,495,719
	Other invested assets (2)		-		-			25,000		25,000
	Other liabilities
	Interest rate swap contracts		-		(9,016	)		-		(9,016	)
	Debt and equity securities sold, not yet purchased		-		(17,101	)		-		(17,101	)
	Total, December 31, 2012, as restated	$	146,258	$	2,323,344		$	25,000	$	2,494,602
	Tower	$	140,695	$	2,042,780		$	25,000	$	2,208,475
	Reciprocal Exchanges		5,563		280,564			-		286,127
	Total, December 31, 2012, as restated	$	146,258	$	2,323,344		$	25,000	$	2,494,602
	(1) $30.3 million of the $77.0 million Other invested assets reported on the consolidated balance sheet at June 30, 2013 is reported at fair value. The remaining $46.7 million of Other invested assets is reported under the equity method of accounting or at amortized cost.
	(2) $25.0 million of the $57.8 million Other invested assets reported on the consolidated balance sheet at December 31, 2012 is reported at fair value. The remaining $32.8 million of Other invested assets is reported under the equity method of accounting or at amortized cost.
	As of June 30, 2013, substantially all of the investment portfolio recorded at fair value was priced based upon quoted market prices or other observable inputs. For investments in active markets, the Company used the quoted market prices provided by the outside pricing services to determine fair value. In circumstances where quoted market prices were unavailable, the Company used fair value estimates based upon other observable inputs including matrix pricing, benchmark interest rates, market comparables and other relevant inputs. When observable inputs were adjusted to reflect management’s best estimate of fair value, such fair value measurements are considered a lower level measurement in the GAAP fair value hierarchy.
	The Company’s process to validate the market prices obtained from the outside pricing sources includes, but is not limited to, periodic evaluation of model pricing methodologies and analytical reviews of certain prices. The Company also periodically performs testing of the market to determine trading activity, or lack of trading activity, as well as market prices. Several securities sold during the quarter were “back-tested” (i.e., the sales price is compared to the previous month end reported market price to determine reasonableness of the reported market price). If management believes that the price provided from the pricing source is distressed, management will use a valuation method that reflects an orderly transaction between market participants, generally a discounted cash flow method that incorporates relevant interest rate, risk and liquidity factors.
	The ability to observe stable prices and inputs may be reduced for highly-customized and illiquid instruments which had been the case for certain non-agency residential and commercial mortgage-backed securities and asset-backed securities in previous periods.
	Substantially all of the portfolio valuations at June 30, 2013, classified as Level 1 or Level 2 in the above table are priced by utilizing the services of several independent pricing services that provide the Company with a price quote for each security. There were no adjustments made to the prices obtained from the independent pricing sources and dealers on securities classified as Level 1 or Level 2.
	In 2013 and 2012, there were no transfers of investments between Level 1 and Level 2 or between Level 2 and Level 3.
	The fair values of the interest rate swaps were derived using an industry standard swap valuation model with market based inputs for swaps having similar characteristics.
	The fair values of the debt and equity securities sold, not yet purchased were derived using quoted prices for similar securities in active markets. These instruments resulted in net realized gains of $0.7 million and $0.8 million for the three and six months ended June 30, 2013, respectively.
The Company holds five securities which are reported in other invested assets and have been classified as Level 3 of the fair value hierarchy. Management utilizes a discounted cash flow analysis to derive the fair values. For one security, which matures in 2015 and whose cash flows are supported by underlying short-term loans, the significant unobservable inputs include the underlying short-term loans’ probability of default and loss severity, and a discount for the security’s lack of marketability. Increases in the probability of default and loss severity assumptions (which generally move directionally with each other) would have the effect of decreasing the fair value of this security. The Company obtains credit ratings on the underlying short-term loans quarterly and considers these ratings when updating its assumptions. A second security is an equity instrument which entitles the Company to residual interests of a finite life special purpose vehicle. The significant unobservable inputs include the estimated losses to be incurred by the vehicle and the equity instrument’s lack of marketability. The Company obtains quarterly financial data from the vehicle and evaluates the estimated incurred loss figure. An increase in the vehicle’s estimated incurred losses would have the effect of decreasing the instrument’s fair value. The remaining three securities are preferred equity interests in limited partnerships that invest in leisure hotels. The preferred interests pay a stated quarterly dividend with residual equity incentives payable after the General Partner’s minimum return thresholds are met. The significant unobservable inputs include the market discount rate and the instruments’ lack of marketability. The three preferred equity interest investments closed in the latter part of June 2013, and were therefore carried at their original cost as of June 30, 2013.
Management is responsible for the determination of the value of the investments carried at fair value and the supporting methodologies and assumptions. Management has reviewed the pricing techniques and methodologies of the independent pricing sources and believes that their policies adequately consider market activity, either based on specific transactions for the issue valued or based on modeling of securities with similar credit quality, duration, yield and structure that were recently traded. Management monitors security-specific valuation trends and discusses material changes or the absence of expected changes with the portfolio managers to understand the underlying factors and inputs and to validate the reasonableness of pricing. Management also back-tests the prices on numerous sales of securities during the year to validate the previous pricing provided as well as utilizes other pricing sources to validate the pricing provided by the Company’s primary provider of the majority of the non-U.S. Treasury securities and non-agency securities included in Level 2.
The following table summarizes the changes in Level 3 assets measured at fair value for the three months ended June 30, 2013 and 2012 for Tower (the Reciprocal Exchanges have no Level 3 assets):
			Three Months Ended
			June 30,
($ in thousands)			2013			2012
Beginning balance, April 1,		$		25,000		$	24,914
Total gains (losses)-realized / unrealized
Included in net income				-			86
Included in other comprehensive income (loss)				-			-
Purchases, issuances and settlements				5,250			-
Net transfers into (out of) Level 3				-			-
Ending balance, June 30,	$			30,250		$	25,000
The following table summarizes the changes in Level 3 assets measured at fair value for the six months ended June 30, 2013 and 2012 for Tower (the Reciprocal Exchanges have no Level 3 assets):
			Six Months Ended
			June 30,
($ in thousands)			2013			2012
Beginning balance, January 1	$			25,000		$	25,000
Total gains (losses)-realized / unrealized - included in net income				-			-
Included in other comprehensive income (loss)				-			-
Purchases, issuances and settlements				5,250			-
Net transfers into (out of) Level 3				-			-
Ending balance, June 30,	$			30,250		$	25,000

Loss_and_Loss_Adjustment_Expen

Loss and Loss Adjustment Expense	6 Months Ended
	Jun. 30, 2013
Loss and Loss Adjustment Expense	'
	Note 9 – Loss and Loss Adjustment Expense
	The following table provides a reconciliation of the beginning and ending consolidated balances for unpaid losses and loss adjustment expense (“LAE”) for the six months ended June 30, 2013 and 2012:
		Six Months Ended June 30,
		2013									2012
	($ in thousands)	Tower			Reciprocal			Total			Tower			Reciprocal			Total
					Exchanges									Exchanges
	Balance at January 1, as restated	$	1,759,888		$	135,791		$	1,895,679		$	1,495,839		$	136,274		$	1,632,113
	Less reinsurance recoverables on unpaid losses		(407,068	)		(52,389	)		(459,457	)		(280,968	)		(11,253	)		(292,221	)
			1,352,820			83,402			1,436,222			1,214,871			125,021			1,339,892
	Net reserves, at fair value, of acquired entities		161,886			-			161,886			-			-			-
	Incurred related to:
	Current year		451,020			57,688			508,708			487,837			57,430			545,267
	Prior years unfavorable/(favorable) development		326,749			167			326,916			78,254			(6,253	)		72,001
	Total incurred		777,769			57,855			835,624			566,091			51,177			617,268
	Paid related to:
	Current year		164,774			36,669			201,443			153,792			31,369			185,161
	Prior years		359,786			10,221			370,007			313,400			30,943			344,343
	Total paid		524,560			46,890			571,450			467,192			62,312			529,504
	Net balance at end of period		1,767,915			94,367			1,862,282			1,313,770			113,886			1,427,656
	Add reinsurance recoverables on unpaid losses		665,172			24,897			690,069			254,516			19,661			274,177
	Balance at June 30,	$	2,433,087		$	119,264		$	2,552,351		$	1,568,286		$	133,547		$	1,701,833
	The consolidated net loss ratio, which includes the Reciprocal Exchanges, was 133.8% and 76.0% for the three months ended June 30, 2013 and 2012, respectively. Excluding the Reciprocal Exchanges, the net loss ratio was 142.7% and 77.3% for the three months ended June 30, 2013 and 2012, respectively.
	The consolidated net loss ratio, which includes the Reciprocal Exchanges, was 99.4% and 70.1% for the six months ended June 30, 2013 and 2012, respectively. Excluding the Reciprocal Exchanges, the net loss ratio was 102.7% and 71.1% for the six months ended June 30, 2013 and 2012, respectively.
	Incurred losses and LAE for the six months ended June 30, 2013 attributable to events of prior years were $326.9 million including the Reciprocal Exchanges and $326.7 million excluding the Reciprocal Exchanges. Excluding the Reciprocal Exchanges, $171.9 million of the prior year reported loss was associated with development in Specialty Insurance and Reinsurance and $163.6 million was associated with Commercial, partially offset by $8.8 million of favorable development in Personal. Reserve strengthening arose primarily from accident years 2008-2011 within the workers’ compensation, CMP liability, other liability and commercial auto liability lines of business offset by small amount of favorable loss development from more recent years within the short tail property lines of business. The Company recognized in the second quarter of 2013 that the higher than expected reported loss development it had been experiencing had become a trend. In response to this recognition, the Company performed a comprehensive update to the internal reserve study to respond to higher than expected reported losses and to update the actuarial assumptions within the study. In conjunction with its comprehensive internal review, the Company also retained its consulting actuary to perform an independent reserve study covering lines of business comprising over 90% of the Company’s loss reserves.
	For these four casualty lines of business, the total amount of actual versus expected loss development observed during the first six months of 2013 was $127.1 million on a net basis. The Company updated the reported loss development triangles and other data used in the underlying reserve analysis to reflect this development and noted that more recent data diagonals indicated a need to increase loss development factors and other actuarial assumptions (for example initial expected loss ratios and net to gross ratios) used to estimate ultimates for the casualty lines of business. As a result of changes in the underlying actuarial assumptions, ultimates for casualty lines of business increased by an additional $201.1 million on a net basis. The increase in ultimates for the casualty lines of business was offset by $0.9 million decrease in ultimates within the short-tail property lines of business.
	For the six months ended June 30, 2013, by line of business, ultimate loss estimates for prior accident years have primarily increased by $122.1 million for workers’ compensation, $89.2 million for commercial package liability, $74.4 million for commercial auto liability and $42.6 million for Other Liability.
	Incurred losses and LAE for the six month ended June 30, 2012 attributable to events of prior years were $72.0 million. Excluding the Reciprocal Exchanges, the incurred losses and LAE from prior accident years were $78.3 million. During the second quarter of 2012, the Company performed a comprehensive reserve study to respond to higher than expected reported losses observed in the first and second quarters of 2012, resulting in increases in ultimate loss estimates of $35.6 million within Commercial and $38.4 million in Specialty and Reinsurance Insurance. $4.3 million of the increase pertained to Personal Insurance. The reserve strengthening was comprised of approximately $39 million in workers’ compensation, $22 million in commercial automobile liability, and smaller changes in other lines. Approximately $51 million of the reserve strengthening pertained to various programs, many of which have been terminated.
	Prior year development is based upon numerous estimates by line of business and accident year. The Company’s management continually monitors claims activity to assess the appropriateness of carried case and incurred but not reported (“IBNR”) reserves, giving consideration to Company and industry trends.
	Included in the reserves for the loss and LAE reserves at June 30, 2013 and December 31, 2012 are $9.8 million and $8.4 million, respectively, of tabular and non-tabular reserve discount for workers’ compensation and excess workers’ compensation claims.
	As of June 30, 2013 the Company had $17.0 million of unamortized reserve for risk premium related to the Merger Transaction. The reserve for risk premium is included in unpaid losses and LAE. The Company recorded $2.2 million of amortization related to the reserve for risk premium for the six months ended June 30, 2013. There was no unamortized reserve for risk premium recorded as of December 31, 2012.
	As disclosed in “Note 1 – Nature of Business”, the Company performed a comprehensive update of its liability for unpaid claims and claims adjustment expenses at June 30, 2013, and was assisted in this review by an independent actuarial consulting firm. In response to its material weakness in internal controls over financial reporting related to loss reserves, the Company will continue to utilize the services of the independent actuarial firm in the Company’s ongoing analyses. Additional reviews of the Company’s loss reserves as of September 30, 2013 are underway, and are expected to be completed in the next several weeks. Substantial additional analysis of the preliminary information is required before a determination can be made as to the impacts, if any, on the Company’s loss reserves.

Shareholders_Equity

Shareholders' Equity	6 Months Ended
	Jun. 30, 2013
Shareholders' Equity	'
	Note 10—Shareholders’ Equity
	Shares of Common Stock Issued
	As previously discussed in “Note 4 – Merger Transaction”, the Merger Transaction was accounted for as a reverse acquisition with TGI treated as the accounting acquirer. Accordingly, TGI’s historical common stock balance immediately prior to the Merger is the historical common stock of TGI adjusted for the number of shares issued in the Merger Transaction by the Company to TGI shareholders (i.e., TGI’s outstanding shares immediately prior to the Merger Transaction multiplied by the conversion ratio of 1.1330).
	Canopius Bermuda had 14,025,737 outstanding common shares outstanding on March 13, 2013 which were sold by Canopius Group to third-party investors in connection with the Merger Transaction.
	For both the three and six months ended June 30, 2013, 2,674 new common shares were issued as the result of employee stock option exercises. For the three and six months ended June 30, 2013, 2,333 and 242,626 new common shares, respectively, were issued after the Merger Transaction as the result of the Company’s restricted stock grants. For the three and six months ended June 30, 2012, no new common shares were issued as the result of employee stock option exercises. For the three and six months ended June 30, 2012, zero and 363,894 new common shares, respectively, (adjusted for the 1.1330 conversion ratio), were issued as the result of restricted stock grants.
	For the three and six months ended June 30, 2013, 891 and 341,598 shares, respectively, of common stock were purchased from employees in connection with the vesting of restricted stock issued under the 2008 Long Term Equity Compensation Plan (the “Plan”). For the three and six months ended June 30, 2012, 561 and 110,304 shares, respectively, (adjusted for the 1.1330 conversion ratio), of common stock were purchased from employees in connection with the vesting of restricted stock issued under the Plan. The shares were withheld at the direction of employees as permitted under the Plan in order to pay the expected amount of tax liability owed by the employees from the vesting of those shares. In addition, for the three and six months ended June 30, 2013, 7,167 and 14,015 shares, respectively, of common stock were surrendered as a result of restricted stock forfeitures. For the three and six months ended June 30, 2012, 5,022 and 9,874 shares, respectively, (adjusted for the 1.1330 conversion ratio) of common stock were surrendered as a result of restricted stock forfeitures.
	In connection with the Merger Transaction, all Treasury shares held by TGI as of the effective date of the Merger Transaction were cancelled. There were 8,058 Treasury shares of the Company held at June 30, 2013.
	Share Repurchase Program
	As part of Tower’s capital management strategy, Tower’s Board of Directors approved a $50 million share repurchase program on May 7, 2013. Purchases under this program can be made from time to time in the open market or in privately negotiated transactions in accordance with applicable laws and regulations. In the six months ended June 30, 2013, no shares of common stock were purchased under this program. TGI’s previously approved share repurchase program expired in March 2013.
	Dividends Declared
	Dividends on common stock and participating unvested restricted stock of $9.5 million and $7.3 million for the three months ended June 30, 2013 and 2012, respectively, were declared and paid. Dividends on common stock and participating unvested restricted stock of $16.7 million and $14.7 million for the six months ended June 30, 2013 and 2012, respectively, were declared and paid.
	On August 6, 2013, the Board of Directors approved a quarterly dividend of $0.165 per share which was paid on September 20, 2013 to shareholders of record as of September 9, 2013.
	The quarterly dividend of $0.165 per share is equivalent to TGI’s historical quarterly dividend of $0.1875 per share adjusted for the conversion ratio of 1.1330 resulting from the Merger Transaction.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2013
Accumulated Other Comprehensive Income	'
	Note 11—Accumulated Other Comprehensive Income
	The following table provides a summary of changes in accumulated other comprehensive income, by component, for the six months ended June 30, 2013, with all amounts reflected net of income taxes and noncontrolling interest:
	($ in thousands)	Unrealized			Gains		Cumulative			Total
		gains (losses)			(losses) on		translation
		on available for			cash flow		adjustments
		sale securities			hedges
	Balance at December 31, 2012, as restated	$	87,412		$	-5,860	$	1,204		$	82,756
	Other comprehensive income before reclassifications, net of tax		(71,210	)		1,406		(2,382	)		(72,186	)
	Amounts reclassified from accumulated other comprehensive income, net of tax		(2,594	)		1,084		-			(1,510	)
	Net current period other comprehensive income		(73,804	)		2,490		(2,382	)		(73,696	)
	Balance at June 30, 2013	$	13,608		$	-3,370	$	(1,178	)	$	9,060
	The following provides a summary of the items that have been reclassified from accumulated other comprehensive income to net income in their entirety during the six months ended June 30, 2013, including the line item on the consolidated statement of operations on which the impact is reflected. Unrealized gains (losses) on available for sale securities are reclassified from accumulated other comprehensive income when a security is sold or when a non-credit impairment is recorded. Gains (losses) on cash flow hedges are reclassified from accumulated other comprehensive income when the related hedged item (subordinated debentures floating rate interest payments) are recorded in the statement of operations.
	($ in thousands)
	Accumulated other comprehensive income components	Amounts reclassified			Affected line item in the consolidated statement of operations
		from accumulated other
		comprehensive income
	Unrealized gains (losses) on available for sale securities	$	-2,594		Other net realized investment gains
			-		Income tax expense
		$	-2,594		Total net of income taxes
	Gains (losses) on cash flow hedges interest rate swaps	$	1,084		Interest expense
			-		Income tax expense
		$	1,084		Total net of income taxes

Debt

Debt

6 Months Ended

Jun. 30, 2013

Debt

'

Note 12—Debt

The Company’s borrowings consisted of the following at June 30, 2013 and December 31, 2012:

June 30, 2013

December 31, 2012

($ in thousands)

Carrying

Fair

Carrying

Fair

Value

Value

Value

Value

Credit facility

$

70,000

$

70,000

$

70,000

$

70,000

Convertible senior notes

146,166

158,243

144,673

152,063

Subordinated debentures

235,058

240,010

235,058

232,678

Total

$

451,224

$

468,253

$

449,731

$

454,741

The fair value of the convertible senior notes is determined utilizing recent transaction prices for these securities between third-party market participants. The fair value of the subordinated debentures is based on discounted cash flow analysis. The significant inputs used for fair value are considered Level 2 in the fair value hierarchy.

Total interest expense incurred, including interest expense on the funds held liabilities, was $7.6 million and $7.9 million for the three months ended June 30, 2013 and 2012, respectively. Total interest expense incurred, including interest expense on the funds held liabilities, was $15.4 million and $16.5 million for the six months ended June 30, 2013 and 2012, respectively.

Subordinated Debentures

The Company and its wholly-owned subsidiaries have issued trust preferred securities through wholly-owned Delaware statutory business trusts. The trusts use the proceeds of the sale of the trust preferred securities and common securities that the Company acquired from the trusts to purchase junior subordinated debentures from the Company with terms that match the terms of the trust preferred securities. Interest on the junior subordinated debentures and the trust preferred securities is payable quarterly. In some cases, the interest rate is fixed for an initial period of five years after issuance and then floats with changes in the London Interbank Offered Rate (“LIBOR”) and in other cases the interest rate floats with LIBOR without any initial fixed-rate period. As of June 30, 2013, The Company had outstanding par of $235.1 million relating to the subordinated debentures.

Interest Rate Swaps

In October 2010, the Company entered into interest rate swap contracts (the “Swaps”) with $190 million notional value to manage interest costs and cash flows associated with the floating rate subordinated debentures. The Swaps have terms of five years. The Swaps convert the subordinated debentures to rates ranging from 5.1% to 5.9%. As of June 30, 2013 and December 31, 2012, the Swaps had a fair value of $6.8 million and $9.0 million in a liability position, respectively, and are reported in Other Liabilities.

The Company has designated and accounts for the Swaps as cash flow hedges. The Swaps are considered to have no ineffectiveness and changes in their fair values are recorded in accumulated other comprehensive income (“AOCI”), net of tax. For the six months ended June 30, 2013 and 2012, $1.1 million and $0.8 million, respectively, were reclassified from AOCI to interest expense for the effects of the hedges. As of June 30, 2013, the Company had collateral on deposit with the counterparty amounting to $6.9 million pursuant to a Credit Support Annex.

Credit Facility

On April 3, 2013, an increase in borrowing capacity up to $220 million became effective pursuant to the second amendment to the credit agreement and consent by and between TGI and Bank of America, N.A., as administrative agent for the lenders party to the credit agreement, dated as of November 26, 2012, and the limited waiver and amendment agreement, dated as of March 3, 2013. The increase in the Credit Facility was negotiated in the event that holders of the convertible senior notes put their bonds to Tower as a result of the Merger Transaction. This put option expired on April 26, 2013. This second amendment and consent also included (i) TGIL as a guarantor of TGI’s obligations under the credit facility and (ii) consent by the lenders to the change in control triggered by the completion of the Merger Transaction. The maturity date and borrowing fees were not changed in this amendment.

The credit facility contains customary covenants for facilities of this type, including restrictions on indebtedness and liens, limitations on mergers, dividends and the sale of assets, and requirements to maintain certain consolidated net worth, debt to capitalization ratios, minimum risk-based capital and minimum statutory surplus. The credit facility also provides for customary events of default, including failure to pay principal when due, failure to pay interest or fees within three days after becoming due, failure to comply with covenants, any representation or warranty made by TGI or the Company as a guarantor being false in any material respect, default under certain other indebtedness, certain insolvency or receivership events affecting the TGI or the Company as guarantor and its material subsidiaries, the occurrence of certain material judgments, or a change in control of the Company, and upon an event of default, the administrative agent (subject to the consent of the requisite percentage of the lenders) may immediately terminate the obligations to make loans and to issue letters of credit, declare the Company’s obligations under the credit facility to become immediately due and payable, and require the Company to deposit in a collateral account cash collateral with a value equal to the then outstanding amount of the aggregate face amount of any outstanding letters of credit. The Company was in compliance with or obtained waivers for all covenants under the credit facility at June 30, 2013.

The Company had $70.0 million outstanding as of June 30, 2013 and December 31, 2012, respectively. The weighted average interest rate on the amount outstanding as of June 30, 2013 was 1.94%.

On October 11, 2013, the Company amended its credit facility to reduce its capacity from $220 million to $70 million and the maturity date was changed to May 30, 2014. In addition, the Company agreed to several restrictions under the credit facility, including:

•

To not enter into any new borrowings under the credit facility;

•

To pledge to the lending banks any proceeds of new capital raises by TGI or TGIL until such time as the credit facility is paid in full;

•

To pledge to the lending banks proceeds from any sales of assets occurring at TGI; and

•

To submit to regulatory authorities, as appropriate, a request for approval to pledge the capital stock of the U.S. based and Bermuda based insurance subsidiaries.

In addition, the following financial covenants are included in the credit facility:

•

Minimum Consolidated Net Worth is the greater of $553,400,000 or 90 % of Consolidated Net Worth as of June 30, 2013; this covenant increases by 90% of any new capital plus 50% of Net Income above $20,000,000;

•

Debt to capitalization ratio limit of 46%;

•

Minimum risk based capital ratio of 175% at December 31, 2013 for Tower Insurance Company of New York and any other insurance subsidiary that exceeds 10% of the consolidated statutory surplus of all insurances subsidiaries;

•

Bermuda enhanced minimum capital requirement of 150% for CastlePoint Re at December 31, 2013 and 110% for TRL;

•

Minimum statutory surplus for all insurance companies of the greater of $419,000,000 or 85% of Combined Surplus at June 30, 2013; and

•

Independent accountant’s annual report shall not be subject to any “going concern” or like qualification or exception. This financial covenant will remain in effect for the year ending December 31, 2013. Although the independent accountant’s report on the consolidated financial statements for the years ended December 31, 2010, 2011 and 2012 contains a “going concern” explanatory paragraph, on November 14, 2013, the Company received a waiver from the lenders under the credit facility in respect of such “going concern” paragraph.

Tower currently is in compliance with all covenants contained in the credit facility.

The credit facility matures on May 30, 2014, at which point any unpaid balance becomes due.

Convertible Senior Notes

In September 2010, the Company issued $150.0 million principal amount of 5.0% convertible senior notes (“the Notes”), which mature on September 15, 2014. Interest on the Notes is payable semi-annually in arrears on March 15 and September 15 of each year, commencing March 15, 2011. The original terms of the Notes allowed Holders to convert their Notes into cash or common shares, at the Company’s option, at any time on or after March 15, 2014 or earlier under certain circumstances determined by: (i) the market price of the Company’s stock, (ii) the trading price of the Notes, or (iii) the occurrence of specified corporate transactions. Upon conversion, the Company intends to settle its obligation either entirely or partially in cash. Upon completion of the merger, the change in control provision of the Indenture was triggered and the Holders were allowed, at their option, to convert their notes into cash or common shares of Tower Group International, Limited. As required by the terms of the Indenture, the Company filed a Fundamental Company Change Notice (“Change Notice”) to the Holders on March 23, 2013. The Change Notice provided Holders the option to convert the Notes into cash or common shares up to and including April 26, 2013. There were no bonds tendered or converted as a result of the Change Notice filing.

The adjusted conversion rate at June 30, 2013 is 42.3690 shares of common stock per $1,000 principal amount of the Notes (equivalent to a conversion price of $23.60 per share), subject to further adjustment upon the occurrence of certain events, including the following: if Tower issues shares of common stock as a dividend or distribution on shares of the common stock , or if Tower effects a share split or share combination; if Tower issues to all or substantially all holders of common stock any rights, options or warrants entitling them, for a period of not more than 45 calendar days after the announcement date of such issuance, to subscribe for or purchase shares of the common stock at a price per share that is less than the average of the last reported sales price of the common stock for the ten consecutive trading day period ending on the date of announcement of such issuance; if Tower distributes shares of its capital stock, other indebtedness, other assets or property of Tower or rights, options or warrants to acquire capital stock or other securities of Tower, to all or substantially all holders of capital stock; if any cash dividend or distribution is made to all or substantially all holders of the common stock, other than a regular quarterly cash dividend that does not exceed $0.110 per share; if Tower makes a payment in respect of a tender offer or exchange offer for common stock, and the cash and value of any other consideration included in the payment per share of common stock exceeds the last reported sale price of the common stock on the trading day next succeeding the last day on which the tenders or exchange may be made.

As a result of the Merger Transaction, it was determined that a fundamental change occurred that would permit the debt holders to tender their bonds to the Company at par plus any accrued and unpaid interest or to convert such debt. Notice of the fundamental change was sent to the debt holders on March 22, 2013, and such notice permitted the debt holders to redeem or convert the securities until April 26, 2013. There were no bonds tendered or converted as a result of the fundamental change.

The proceeds from the issuance of the Notes were allocated to the liability component and the embedded conversion option, or equity component. The equity component was reported as an adjustment to paid-in-capital, net of tax, and is reflected as an original issue discount (“OID”). After considering the contractual interest payments and amortization of the original issue discount, the Notes’ effective interest rate is 7.2%. Transaction costs of $0.4 million associated with the equity component were netted with the equity component in paid-in-capital. Interest expense, including amortization of deferred origination costs, recognized on the Notes was $5.9 million for the six months ended June 30, 2013.

The following table shows the amounts recorded for the Notes as of June 30, 2013 and December 31, 2012:

June 30,

December 31,

($ in thousands)

2013

2012

Liability component

Outstanding principal

$

150,000

$

150,000

Unamortized OID

(3,834

)

(5,327

)

Liability component

146,166

144,673

Equity component, net of tax

$

7,469

$

7,469

To the extent the market value per share of the Company’s common stock exceeds the conversion price, the Company will use the “treasury stock” method in calculating the dilutive effect on earnings per share.

Convertible Senior Notes Hedge and Warrant Transactions

In connection with the offering of the Notes, the Company also entered into convertible senior notes hedge transactions (the “Note Hedges” or “purchased call options”) and warrant transactions (the “Warrants”) with respect to its common stock with financial institutions. The Note Hedges and Warrants were intended generally to reduce the potential dilution of the Company’s common stock and to offset potential cash payments in excess of the principal of the Notes upon conversion. The Note Hedges and Warrants were separate transactions, entered into by the Company with the financial institutions, and were not part of the terms of the Notes.

In March 2013, as a result of the Merger Transaction, the Company terminated the Note Hedges and Warrants. The Company received $2.4 million and paid $1.0 million to terminate the Note Hedges and Warrants, respectively. The effects of the terminations and an associated tax adjustment of $0.8 million were recorded directly to paid-in-capital in shareholders’ equity.

Stock_Based_Compensation

Stock Based Compensation	6 Months Ended
	Jun. 30, 2013
Stock Based Compensation	'
	Note 13—Stock Based Compensation
	2008 Long-Term Equity Compensation Plan (“2008 LTEP”)
	In 2008, the Company’s Board of Directors adopted and its shareholders approved the 2008 LTEP, which amended and revised the 2004 Long-Term Equity Compensation Plan.
	The 2008 LTEP provides for the granting of non-qualified stock options, incentive stock options (within the meaning of Section 422 of the Internal Revenue Code), stock appreciation rights (“SARs”), restricted stock and restricted stock unit awards, performance shares and other cash or share-based awards. The maximum amount of share-based awards authorized is 2,325,446 of which 30,376 are available for future grants as of June 30, 2013.
	2013 Long-Term Incentive Plan (“2013 LTIP”)
	The Compensation Committee of the Board of Directors has established, beginning in 2013 a new Long Term Incentive Plan (the “2013 LTIP”), to replace the Company’s existing 2008 Long Term Equity Compensation Plan. The 2013 LTIP was approved by the shareholders in May 2013. The maximum amount of share-based awards authorized is 2,150,000 of which 2,147,531 are available for future grants as of June 30, 2013.
	Restricted Stock
	The following table provides an analysis of restricted stock activity for the six months ended June 30, 2013 and 2012 (historical share counts and fair values have been adjusted for the 1.1330 share conversion ratio, as discussed more fully in “Note 4 – Merger Transaction”):
		Six Months Ended June 30,
		2013					2012
		Number			Weighted		Number			Weighted
		of Shares			Average		of Shares			Average
					Grant Date					Grant Date
					Fair Value					Fair Value
	Outstanding, January 1		1,015,902		$	20.19		1,120,091		$	20.69
	Granted		242,626			18.09		363,894			20.37
	Vested		(953,242	)		20.43		(439,734	)		21.07
	Forfeitures		(14,015	)		19.26		(9,874	)		20.83
	Outstanding, June 30,		291,271		$	17.68		1,034,377		$	20.38
	On March 13, 2013, 525,548 shares vested as a result of the Merger Transaction.
	Stock Options
	The following table provides an analysis of stock option activity for the six months ended June 30, 2013 and 2012 (historical share counts and fair values have been adjusted for the 1.1330 share conversion ratio, as discussed more fully in “Note 4 – Merger Transaction”):
		Six Months Ended June 30,
		2013					2012
		Number of			Average		Number of			Average
		Shares			Exercise		Shares			Exercise
					Price					Price
	Outstanding, January 1		969,307		$	17.78		969,315		$	17.78
	Exercised		(2,674	)		16.48		-			-
	Forfeitures and expirations		(7,657	)		17.72		-			-
	Outstanding, June 30		958,976		$	17.78		969,315		$	17.78
	Exercisable, June 30		958,976		$	17.78		969,315		$	17.78
	Stock Based Compensation Expense
	The following table provides an analysis of stock based compensation expense for the six months ended June 30, 2013 and 2012:
		Six Months
		Ended June 30,
	($ in thousands)	2013			2012
	Restricted stock
	Expense, net of tax	$	8,204		$	896
	Value of shares vested		21,042			8,576
	Value of unvested shares		5,974			19,257
	Stock options
	Intrinsic value of outstanding options		3,471			1,632
	Intrinsic value of vested outstanding options		3,471			1,632
	Unrecognized compensation expense
	Unvested restricted stock, net of tax		5,974			12,791
	Weighted average years over which expense will be recognized		3.6			2.5

Income_Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2013
Income Taxes	'
	Note 14—Income Taxes
	Under current Bermuda Law the Company is not required to pay any taxes on Bermuda based income or capital gains. The Company has received an undertaking from the Minister of Finance in Bermuda that in the event of such taxes being imposed, the Company will be exempted from taxation until the year 2035 pursuant to the Bermuda Exempted Undertakings Tax Protection Act of 1966. The Company’s United States-based subsidiaries are subject to federal, state and local taxes, as applicable, on income and capital gains earned by those subsidiaries.
	The Company and TRL, its Bermuda reinsurance subsidiary, are deemed to have permanent establishments in Bermuda. The Bermuda companies have not and do not expect to conduct business that is through a permanent establishment in the U.S. All transactions between Tower’s U.S.-based subsidiaries and the Bermuda companies are subject to transfer pricing rules. The Company has executed certain reinsurance treaties and service agreements between its U.S.-based subsidiaries and TRL and management believes these arrangements to be conducted at current market rates and in accordance with transfer pricing rules.
	During the three and six months ended June 30, 2013, Tower’s U.S. taxed subsidiaries (excluding the Reciprocal Exchanges) recognized pre-tax losses of approximately $493.8 million and $509.3 million, respectively. This resulted in $111.0 million of net operating loss carryforwards in the deferred tax inventory and a net deferred tax asset, before any valuation allowance, of $141.5 million (excluding the Reciprocal Exchanges) as of June 30, 2013. Including the Reciprocal Exchanges, the net deferred tax asset, before any valuation allowance, was $134.5 million.
	At June 30, 2013, a full valuation allowance was recorded against the deferred tax assets. In the second quarter of 2013
	$113.9 million of the valuation allowance was recorded in income tax expense (benefit) in the statement of operations and $25.8 million was recorded in other comprehensive income as a direct charge to shareholder’s equity (as a component of accumulated other comprehensive income).
	Management in its judgment concluded that a full valuation allowance was required for Tower’s U.S. taxed subsidiaries after its consideration of the cumulative three-year pre-tax loss in its U.S. taxed subsidiaries resulting from certain second quarter 2013 events and the 2012 pre-tax loss of $61.3 million. In the second quarter of 2013, the following items contributed significantly to pre-tax losses in Tower’s U.S. taxed subsidiaries: (i) $325.6 million of prior year reserve strengthening was recorded, of which $149.7 million related to Tower’s U.S. taxed subsidiaries, and (ii) a $214.0 million goodwill impairment charge, of which $185.9 million related to Tower’s U.S. taxed subsidiaries. Management believes that the negative evidence associated with the realizability of its net deferred tax asset, including the cumulative three-year pre-tax loss, the prior year adverse reserve development recorded in 2012 and 2013, and the effects of Hurricane Irene in 2011 and Superstorm Sandy in 2012 outweighed the positive evidence that the deferred tax assets, including the net operating loss carryforward, would be realized, and recorded the full valuation allowance.
	The Company’s effective tax rates of 0.4% and 0.7% for the three and six months ended June 30, 3013, respectively, reflect the recording of the full valuation allowance in the second quarter of 2013. Prior to the second quarter of 2013, Tower calculated an estimated annual effective tax rate on its U.S. taxed subsidiaries that differed from the U.S. statutory rate due to costs associated with tax exempt interest and dividends received deductions.
	The United States also imposes an excise tax on insurance and reinsurance premiums paid to non-U.S. insurers or reinsurers with respect to risks located in the United States. The rates of tax, unless reduced by an applicable U.S. tax treaty, are four percent for non-life insurance premiums and one percent for life insurance and all reinsurance premiums. The Company incurs federal excise taxes on certain of its reinsurance transactions, including amounts ceded through intercompany transactions. Tower incurred $6.3 million of federal excise tax in 2013.

Earnings_Loss_per_Share

Earnings (Loss) per Share	6 Months Ended
	Jun. 30, 2013
Earnings (Loss) per Share	'
	Note 15—Earnings (Loss) per Share
	Undistributed net earnings (net income less dividends declared during the period) are allocated to both common stock and unvested share-based payment awards (“unvested restricted stock”). Because the common shareholders and unvested restricted stock holders share in dividends on a 1:1 basis, the earnings per share on undistributed earnings is equivalent, however, undistributed losses are allocated only to common stock holders. Undistributed earnings are allocated to all outstanding share-based payment awards, including those for which the requisite service period is not expected to be rendered.
	The following table shows the computation of the earnings per share (historical earnings per share amounts have been adjusted for the 1.1330 share conversion ratio in connection with the Merger Transaction):
		Three Months						Six Months
		Ended June 30,						Ended June 30,
	($ in thousands, except per share amounts)	2013			2012			2013			2012
	Numerator
	Net income (loss) attributable to Tower Group International, Ltd.	$	(507,342	)	$	(16,809	)	$	(494,425	)	$	2,356
	Less: Allocation of income for unvested participating restricted stock		-			-			-			-
	Less: Dividends on unvested participating restricted stock		(48	)		(173	)		(215	)		(347	)
	Net income available to common shareholders - Basic		(507,390	)		(16,982	)		(494,640	)		2,009
	Reallocation of income for unvested participating restricted stock		-			-			-			-
	Net income available to common shareholders - Diluted		(507,390	)		(16,982	)		(494,640	)		2,009
	Denominator
	Basic earning per share denominator		57,135			43,289			51,487			43,340
	Effect of dilutive securities		-			-			-			70
	Diluted earnings per share denominator		57,135			43,289			51,487			43,410
	Earnings (loss) per share attributable to Tower Group International, Ltd. - Basic
	Common stock:
	Distributed earnings	$	0.17		$	0.17		$	0.34		$	0.34
	Undistributed earnings	$	(9.05	)	$	(0.56	)	$	(9.95	)	$	(0.29	)
	Total	$	(8.88	)	$	(0.39	)	$	(9.61	)	$	0.05
	Earnings (loss) per share attributable to Tower Group International, Ltd. - Diluted	$	(8.88	)	$	(0.39	)	$	(9.61	)	$	0.05
	The computation of diluted earnings (loss) per share excludes outstanding options and other common stock equivalents in periods where inclusion of such potential common stock instruments would be anti-dilutive. For the three and six months ended June 30, 2013, 958,980 and, 958,980, respectively, options to purchase Company shares were excluded from the computation of diluted earnings (loss) per share because the exercise price of the options was greater than the average market price. For the three and six months ended June 30, 2012, 969,310 and, 190,500, respectively, options to purchase Company shares were excluded from the computation of diluted earnings (loss) per share because the exercise price of the options was greater than the average market price.

Statutory_Financial_Informatio

Statutory Financial Information	6 Months Ended
	Jun. 30, 2013
Statutory Financial Information	'
	Note 16—Statutory Financial Information
	The Company is required to maintain minimum capital and surplus for each of its insurance subsidiaries. Management determined the minimum capital and surplus requirements for its U.S. based insurance subsidiaries to be at a level above “Company Action Level.”
	Company Action Level is a calculated capital and surplus number using a risk-based formula adopted by the state insurance regulators. The basis for this formula is the NAIC’s risk-based capital (RBC) system and is designed to measure the adequacy of U.S. regulated insurer’s statutory capital and surplus compared to risks inherent in its business. If an insurance entity falls into Company Action Level, its management is required to submit a comprehensive financial plan that identifies the conditions that contributed to the financial condition. This plan must contain proposals to correct the financial problems and provide projections of the financial condition, both with and without the proposed corrections. The plan must also outline the key assumptions underlying the projections and identify the quality of, and problems associated with, the underlying business. Depending on the level of actual capital and surplus in comparison to the Company Action Level, the state insurance regulators could increase their regulatory oversight, restrict the placement of new business, or place the company under regulatory control. Bermuda based insurance entity’s minimum capital and surplus requirements are calculated from a solvency formula prescribed by the BMA.
	Tower has in place several intercompany reinsurance transactions between its U.S. based insurance subsidiaries and its Bermuda based insurance subsidiaries. The U.S. based insurance subsidiaries have historically reinsured on a quota share basis obligations to CastlePoint Re, the Company’s other Bermuda based reinsurer. The 2013 obligations that CastlePoint Re assumes from the U.S. based insurance subsidiaries are then retroceded to TRL. In addition, CastlePoint Re also entered into a loss portfolio transaction with TRL where its reserves associated with the U.S. insurance subsidiary business for underwriting years prior to 2013 were all transferred to TRL. Therefore, TRL recorded $175 million of reserve strengthening on its balance sheet as of June 30, 2013 and, consequently, the financial result of such development was a reduction in the capital of TRL to $8.3 million at June 30, 2013. In addition TRL is required to collateralize the additional $175 million of assumed reserves in a trust for the benefit of TICNY, the lead pool company of the U.S. insurance companies. TRL had unencumbered liquid assets of $96 million at June 30, 2013, and during October of 2013, TRL commuted two reinsurance treaties which provided an additional $79 million in unencumbered assets.
	The funding of the trust to support TICNY’s reinsurance recoverable has not yet occurred and requires approval by the Bermuda regulator. The Company can provide no assurance that it will be successful in finalizing the business combination or in funding the trust. If the trust funding is not approved, 1) the statutory capital of TICNY would be at a level that the New York Department of Financial Services could place TICNY under regulatory control; and 2) Tower Group, Inc. could violate the revised debt covenants of the bank credit facility at December 31, 2013, which violation, if not waived, would result in a cross default of our convertible notes. Statutory capital and surplus would be further reduced by whatever amounts are due from CastlePoint Re or from TRL that are not supported by assets held in trust. At June 30, 2013, all other U.S. based insurance subsidiaries maintained capital and surplus above company action level.
	As of June 30, 2013, TRL had capital and surplus that did not meet the minimum capital and surplus requirements of the BMA.
	The Company has discussed with the BMA its intention to combine a substantial portion of the business and the capital of CastlePoint Re with TRL. Through this combination, management believes that the combined entity’s capital would meet the minimum capital and surplus thresholds determined by the BMA. The Company is currently developing this plan and expects to deliver this plan to its Bermuda regulators in the next several weeks. The Company cannot provide assurance that it will be successful in pursuing this alternative. Should the business combination not be approved, TRL would be operating at a capital level that is below the regulatory minimums as designated by the BMA. As such, TRL may be subject to significant additional regulatory oversight or, in the event that such oversight did not satisfy the BMA, placed into liquidation.
	Two Insurance Subsidiaries that do not constitute “significant subsidiaries” of the Company under Regulation S-X are in discussions with the insurance regulatory authority in their state of domicile with respect to the imposition of restrictions on the operation of their businesses. These discussions may result in such subsidiaries’ agreeing to provide the regulatory authority with increased information with respect to their business, operations and financial condition, as well as limitations on payments and transactions outside the ordinary course of business and material changes in their management and related matters.
	In addition, U.S. state insurance regulations restrict the ability of our insurance subsidiaries to pay dividends to Tower Group International, Ltd. as their ultimate parent (the “Holding Company”). Generally dividends may only be paid out of earned surplus, and the amount of an insurer’s surplus following payment of any dividends must be reasonable in relation to the insurer’s outstanding liabilities and adequate to meet its financial needs. As of June 30, 2013, no dividends may be paid to the Holding Company without the approval of the state regulators or BMA, as appropriate.

Segment_Information

Segment Information	6 Months Ended
	Jun. 30, 2013
Segment Information	'
	Note 17—Segment Information
	The accounting policies of the segments are the same as those described in TGI’s summary of significant accounting policies in its Amendment No. 2 to the Annual Report on Form 10-K for the year ended December 31, 2012.
	As disclosed in “Note 1 – Nature of Business”, the Company revised its business segments to present Commercial Insurance, Specialty Insurance and Reinsurance and Personal Insurance segments. The Company has restated prior period segments to be consistent with the current presentation.
	Segment performance is evaluated based on segment profit, which excludes investment income, realized gains and losses, interest expense, income taxes and corporate expenses. Intangibles and goodwill are allocated to each of the segments. All other assets are not allocated to segments because the other assets are considered in total by management for decision-making purposes.
	The Personal Insurance segment, which includes the Reciprocal Exchanges and the management companies, reports the management fees earned by Tower from the Reciprocal Exchanges for underwriting, investment management and other services as a reduction to other underwriting expenses. The effects of these management fees between Tower and the Reciprocal Exchanges are eliminated in consolidation to derive consolidated net income. However, the management fee income is reported in net income attributable to Tower Group International, Ltd. and included in basic and diluted earnings (loss) per share.
	Business segment results are as follows:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Commercial Insurance Segment
	Revenues
	Premiums earned	$	170,832		$	193,793		$	348,827		$	381,651
	Ceding commission revenue		(8,301	)		(732	)		(8,237	)		(2,778	)
	Policy billing fees		1,422			1,390			2,792			2,903
	Total revenues		163,953			194,451			343,382			381,776
	Expenses
	Loss and loss adjustment expenses		249,906			155,395			373,293			272,239
	Underwriting expenses		66,614			63,832			129,383			128,245
	Total expenses		316,520			219,227			502,676			400,484
	Underwriting profit (loss)	$	(152,567	)	$	(24,776	)	$	(159,294	)	$	(18,708	)
	Specialty Insurance and Reinsurance Segment
	Revenues
	Premiums earned	$	122,211		$	143,857		$	251,999		$	253,834
	Ceding commission revenue		3,528			4,626			6,751			6,682
	Total revenues		125,739			148,483			258,750			260,516
	Expenses
	Loss and loss adjustment expenses		248,466			125,814			321,442			210,408
	Underwriting expenses		56,772			50,122			106,915			88,851
	Total expenses		305,238			175,936			428,357			299,259
	Underwriting profit (loss)	$	(179,499	)	$	(27,453	)	$	(169,607	)	$	(38,743	)
	Personal Insurance Segment
	Revenues
	Premiums earned	$	125,321		$	122,503		$	239,424		$	244,826
	Ceding commission revenue		12,044			6,186			22,908			11,339
	Policy billing fees		1,899			1,610			3,679			3,231
	Total revenues		139,264			130,299			266,011			259,396
	Expenses
	Loss and loss adjustment expenses		61,520			68,566			140,889			134,621
	Underwriting expenses		63,709			56,164			121,696			107,617
	Total expenses		125,229			124,730			262,585			242,238
	Underwriting profit (loss)	$	14,035		$	5,569		$	3,426		$	17,158
	Tower	$	14,139		$	9,376		$	16,156		$	21,213
	Reciprocal Exchanges		(104	)		(3,807	)		(12,730	)		(4,055	)
	Total underwriting profit (loss)	$	14,035		$	5,569		$	3,426		$	17,158
	The following table reconciles revenue by segment to consolidated revenues:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Commercial Insurance segment	$	163,953		$	194,451		$	343,382		$	381,776
	Specialty Insurance and Reinsurance segment		125,739			148,483			258,750			260,516
	Personal Insurance segment		139,264			130,299			266,011			259,396
	Total segment revenues		428,956			473,233			868,143			901,688
	Net investment income		28,402			31,781			58,719			65,724
	Net realized gains (losses) on investments, including other-than-temporary impairments		(2,034	)		19			4,817			3,347
	Corporate and other		5,194			1,359			5,322			1,856
	Consolidated revenues	$	460,518		$	506,392		$	937,001		$	972,615
	The following table reconciles the results of the Company’s individual segments to consolidated income before income taxes:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Commercial Insurance segment underwriting profit (loss)	$	(152,567	)	$	(24,776	)	$	(159,294	)	$	(18,708	)
	Specialty Insurance and Reinsurance segment underwriting profit (loss)		(179,499	)		(27,453	)		(169,607	)		(38,743	)
	Personal Insurance segment underwriting profit (loss)		14,035			5,569			3,426			17,158
Net investment income		28,402			31,781			58,719			65,724
Net realized gains on investments, including other-than-temporary impairments		(2,034	)		19			4,817			3,347
Corporate and other		(2,297	)		(1,809	)		(5,239	)		(4,173	)
Acquisition-related transaction costs		(665	)		(720	)		(19,721	)		(1,982	)
Interest expense		(7,635	)		(7,902	)		(15,443	)		(16,513	)
Goodwill impairment		(214,049	)		-			(214,049	)		-
Equity income in unconsolidated affiliate		7,838			-			7,966			-
Income before income taxes	$	(508,471	)	$	(25,291	)	$	(508,425	)	$	6,110

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2013
Contingencies	'
	Note 18—Contingencies
	Legal Proceedings
	On August 20, 2013, Robert P. Lang, a purported shareholder of Tower Group International Ltd. (“Tower”), filed a purported class action complaint (the “Lang Complaint”) against Tower and certain of its officers in the United States District Court for the Southern District of New York. The Lang Complaint alleges that Tower and certain of its officers violated federal securities laws and seeks unspecified damages. On September 3, 2013, a second purported shareholder class action complaint was filed by Dennis Feighay, another purported Tower shareholder, containing similar allegations to those set forth in the Lang Complaint (the “Feighay Complaint”). On October 4, 2013, a third complaint was filed by Sanju Sharma (the “Sharma Complaint”). The Sharma Complaint names as defendants Tower and certain of its officers, and purports to be asserted on behalf of a plaintiff class who purchased Tower stock between May 10, 2011 and September 17, 2013. On October 18, 2013, an amended complaint was filed in the Sharma case (the “Sharma Amended Complaint”). The Sharma Amended Complaint alleges additional false and misleading statements, and purports to be asserted on behalf of a plaintiff class who purchased Tower stock between March 1, 2011 and October 7, 2013. On October 21, 2013, a number of motions were filed seeking to consolidate the shareholder class actions into one matter and for appointment of a lead plaintiff. The Company believes that it is not probable that the Lang and Feighay Complaints and the Sharma Amended Complaint will result in a loss, and that the amount of any loss cannot reasonably be estimated.
	On October 18, 2013, Cinium Financial Services Corporation (“Cinium”) and certain other affiliated parties (collectively, “Plaintiffs”) filed a complaint against, among others, Tower, CastlePoint Insurance Company (“CastlePoint”), an indirect wholly owned subsidiary of Tower, and certain officers of Tower (the “Cinium Complaint”) in New York State Supreme Court. CastlePoint is a party to a Securityholders’ Agreement, dated as of June 14, 2012 (the “Securityholders’ Agreement”), among certain parties including Plaintiffs, and is also the holder of a senior note issued by Cinium dated May 15, 2012 that is convertible into shares of Cinium common stock (the “Senior Note”). Plaintiffs seek, among other things, (i) a declaratory judgment that CastlePoint has no right to exercise any control over Cinium under the Securityholders’ Agreement or to convert the Senior Note without prior regulatory approval; (ii) rescission of the Senior Note and Securityholders’ Agreement based on alleged fraudulent misrepresentations by Tower at the time these agreements were entered into; and (iii) damages of $150 million for alleged breach of fiduciary duties to Cinium and its shareholders by certain directors. The Company believes that it is not probable that the Cinium Complaint will result in a loss, and that the amount of any loss cannot reasonably be estimated.
	From time to time, the Company is involved in other various legal proceedings in the ordinary course of business. The Company does not believe that the resolution of any currently pending legal proceedings, either individually or taken as a whole, will have a material adverse effect on its business, results of operations or financial condition.

Subsequent_Events

Subsequent Events	6 Months Ended
	Jun. 30, 2013
Subsequent Events	'
	Note 19—Subsequent Events
	Miscellaneous
	On August 19, 2013, Tower announced it terminated its previously announced agreement to acquire American Safety Reinsurance, Ltd., the Bermuda-based reinsurance subsidiary of American Safety Insurance Holdings, Ltd., from Fairfax Financial Holdings Limited. Tower received $5 million in exchange for the termination of such agreement.
	In August 2013, management has begun to reorganize the way in which it will manage the business for operating decisions and assessing profitability. This reorganization is attributed to events occurring subsequent to the second quarter of 2013. As a result, the Company will reassess its segment reporting for the third quarter 2013 financial reporting purposes.
	On October 11, 2013, the Company amended its Credit Facility to reduce its capacity from $220 million to $70 million and change its maturity date to May 30, 2014. See “Note 1 – Nature of Business” for additional information.
	Reinsurance Agreements
	On October 1, 2013, Tower announced that it entered into agreements with three reinsurers, Arch Reinsurance Ltd. (“Arch”), Hannover Re (Ireland) Plc. (“Hannover”) and Southport Re (Cayman), Ltd. (“Southport Re”). These agreements provided for surplus enhancement and improved certain financial leverage ratios, while increasing the Company’s financial flexibility. The agreements with Arch and Hannover each consists of one reinsurance agreement while the arrangement with Southport Re consists of several reinsurance agreements. Each of these is described below.
	The first agreement was between TICNY on its behalf and on behalf of each of its pool participants and Arch. Under this multi-line quota share agreement, TICNY will cede 17.5% on a quota share certain brokerage commercial automobile liability, brokerage commercial multi-peril property, brokerage commercial multi-peril liability and brokerage other liability (mono line liability) business. The agreement covers losses occurring on or after July 1, 2013 for policies in-force as at June 30, 2013 and policies written or renewed from July 1, 2013 to December 31, 2013. The agreement has a special termination clause whereby either party may terminate the agreement upon the occurrence of certain circumstances, including an A.M. Best financial strength rating downgrade to below A-. As noted below, A.M. Best downgraded Tower’s financial strength rating to B++. Neither party has provided notice to terminate the agreement.
	The second agreement was between TICNY, on its behalf and on behalf of each of its pool participants, and Hannover. Under this multi-line quota share agreement, TICNY will cede 14% on a quota share certain brokerage commercial automobile liability, brokerage commercial multi-peril property, brokerage commercial multi-peril liability, brokerage other liability (mono line liability) and brokerage workers’ compensation business. The agreement covers losses occurring on or after July 1, 2013 for policies in-force as at June 30, 2013 and policies written or renewed from July 1, 2013 to December 31, 2013. The agreement has a special termination clause whereby either party may terminate the agreement upon the occurrence of certain circumstances, including an A.M. Best financial strength rating downgrade to below A-. As noted below, A.M. Best downgraded Tower’s financial strength rating to B++. Neither party has provided notice to terminate the agreement.
	The third reinsurance arrangement with Southport Re consisted of two separate reinsurance agreements with TICNY, on its behalf and on behalf of each of its pool participants, and a third reinsurance agreement with Tower Reinsurance, Ltd. (“TRL”). Under the first of the agreements with TICNY, TICNY ceded to Southport Re a 30% quota share of its workers’ compensation and employer’s liability business. The agreement covers losses occurring on or after July 1, 2013 for policies in force at June 30, 2013 and policies written or renewed during the term of the agreement. Under the second of these agreements with TICNY, an aggregate excess of loss agreement, Southport Re assumed a portion of the losses incurred by TICNY on its workers’ compensation and employer’s liability business between January 1, 2011 and June 30, 2013, but paid by TICNY on or after June 1, 2013. Finally, TRL, a wholly-owned Bermuda-domiciled reinsurance subsidiary of Tower, also entered into an aggregate excess of loss agreement with Southport Re, in which Southport Re assumed a portion of the losses incurred by TRL on its assumed workers’ compensation and employer’s liability business between January 1, 2011 and June 30, 2013, but paid by TRL on or after June 1, 2013. The agreement has a special termination clause whereby either party may terminate the agreement upon the occurrence of certain circumstances, including an A.M. Best financial strength rating downgrade to below A-. As noted below, A.M. Best downgraded Tower’s financial strength rating to B++. Neither party has provided notice to terminate the agreement.
	A.M. Best, Fitch and Demotech Downgrade the Company’s Financial Strength and Issuer Credit Ratings
	On October 7, 2013, Fitch downgraded Tower’s Issuer Default Rating from “BBB” to “B” and Tower’s insurance subsidiaries’ Insurer Financial Strength ratings from “A-” to “BB”. The ratings will continue to remain on negative watch until Tower’s exploration of strategic alternatives.
	On October 8, 2013, A.M. Best, lowered Tower’s issuer credit, as well as its financial strength ratings, from “A-” (Excellent) to “B++” (Good). The ratings remain under review with negative implications pending further discussions between A.M. Best and Tower’s management.
	On October 7, 2013, Demotech lowered its rating on TICNY and three other U.S. based insurance subsidiaries (Kodiak Insurance Company, Massachusetts Homeland Insurance Company and York Insurance Company of Maine) from A’ (A prime) to A (A exceptional). In addition, Demotech removed its previous A’ (A prime) rating on six other U.S. based insurance subsidiaries (CastlePoint Florida Insurance Company, CastlePoint Insurance Company, CastlePoint National Insurance Company, Hermitage Insurance Company, North East Insurance Company and Preserver Insurance Company). Demotech also affirmed its A ratings on Adirondack Insurance Exchange, New Jersey Skylands Insurance Association, New Jersey Skylands Insurance Company and Mountain Valley Indemnity Company.
	Management expects these rating actions, in combination with other items that have impacted the Company in the second quarter of 2013, to result in a decrease in the amount of premiums the insurance subsidiaries are able to write. The net written premiums in the Commercial Insurance segment were $169.1 million and $343.6 million for the three and six months ended June 30, 2013. The net written premiums in the Specialty Insurance and Reinsurance segment were $103.7 million and $306.6 million for the three and six months ended June 30, 2013. Business written through program underwriting agents and assumed reinsurance generally requires an A.M. Best rating of A- or greater.
	Regulation
	Two insurance subsidiaries that do not constitute “significant subsidiaries” of the Company under Regulation S-X are in discussions with the insurance regulatory authority in their state of domicile with respect to the imposition of restrictions on the operation of their businesses. These discussions may result in such subsidiaries’ agreeing to provide the regulatory authority with increased information with respect to their business, operations and financial condition, as well as limitations on payments and transactions outside the ordinary course of business and material changes in their management and related matters.

Accounting_Policies_and_Basis_1

Accounting Policies and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2013
Basis of Presentation	'
	Basis of Presentation
	The Merger Transaction was accounted for as a reverse acquisition, under which TGI was identified and treated as the accounting acquirer. As such, the Company’s unaudited consolidated financial statements include the accounts and operations of TGI and its insurance subsidiaries, managing general agencies and management companies as its historical financial statements, with the results of Tower Group International, Ltd., as accounting acquiree, being included from March 13, 2013, the effective date of the Merger Transaction. The unaudited consolidated financial statements also include the accounts of Adirondack Insurance Exchange, a New York reciprocal insurer, and New Jersey Skylands Insurance Association, a New Jersey reciprocal insurer (together, the “Reciprocal Exchanges”). The Company does not own the Reciprocal Exchanges but manages their business operations through its wholly-owned management companies.
	The accompanying unaudited consolidated financial statements included in this report have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and with the instructions to Securities and Exchange Commission (“SEC”) Form 10-Q and Article 10 of SEC Regulation S-X. The principles for condensed interim financial information do not require the inclusion of all the information and footnotes required by GAAP for complete financial statements. Therefore, these financial statements should be read in conjunction with TGI’s consolidated financial statements as of and for the year ended December 31, 2012 and notes thereto included in TGI’s Amendment No. 2 to the Annual Report on Form 10-K for the year ended December 31, 2012. The accompanying consolidated financial statements have not been audited by an independent registered public accounting firm in accordance with standards of the Public Company Accounting Oversight Board (United States) but, in the opinion of management, such financial statements include all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the Company’s financial position, results of operations and cash flows. All intercompany transactions have been eliminated in consolidation.
Use of Estimates	'
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Moreover, the results of operations for the six months ended June 30, 2013 may not be indicative of the results that may be expected for the year ending December 31, 2013.
Intercompany Transactions	'
	Intercompany transactions
	In the first quarter of 2012, the Company transferred a licensed insurance subsidiary shell to the Reciprocal Exchanges and received cash for its statutory book value. At the date of the transfer, the Company’s GAAP carrying basis in this subsidiary exceeded the statutory book value and the transfer resulted in a loss to the Company of $1.8 million. Since this was a non-recurring transaction between entities under common control, assets were transferred at historical book value. The difference in the consideration paid and the book value of the assets transferred was treated as an adjustment to equity. This transaction had no effect on consolidated shareholders’ equity.
Reclassifications and Adjustments	'
	Reclassifications and Adjustments
	Since the Company accounted for the Merger Transaction as a reverse acquisition and recapitalization, it has retroactively restated Common Stock, Treasury Stock and Paid-in-Capital accounts and earnings per share for periods prior to the Merger Transaction to reflect the historical capitalization of TGI, adjusted for the 1.1330 conversion ratio as discussed in “Note 4 – Merger Transaction”. Certain other reclassifications have also been made to prior years’ financial information to conform to the current year presentation, including the changes in segment presentation discussed in “Note 1 – Nature of Business.”
	The table below reflects the previously reported and revised shareholders’ equity accounts resulting from the Merger Transaction:
		As previously			Revised
	($ in thousands, except per share amounts)	Reported			Amount
	As of December 31, 2012
	Common stock	$	469		$	530
	Treasury stock		(181,435	)		(181,435	)
	Paid-in-capital		780,097			780,036
	For the three-months ended June 30, 2012
	Earnings (Loss) per Share:
	Basic	$	(0.43	)	$	(0.39	)
	Diluted		(0.43	)		(0.39	)
	Weighted average common shares outstanding
	Basic		39,117			43,289
	Diluted		39,117			43,289
	For the six-months ended June 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.06		$	0.05
	Diluted		0.06			0.05
	Weighted average common shares outstanding
	Basic		39,206			43,340
	Diluted		39,268			43,410
	See “Note 15 – Earnings (loss) per Share” for the computation of the earnings per share.
Accounting Pronouncements	'
	Accounting Pronouncements
	Accounting guidance adopted in 2012 and 2013
	In July 2012, the Financial Accounting Standards Board (“FASB”) issued amended guidance on testing indefinite-lived intangible assets for impairment. This guidance is intended to reduce the cost and complexity of the annual impairment test by allowing an entity to utilize more qualitative factors and is effective for annual and interim tests performed for fiscal years beginning after September 15, 2012. The Company will consider this guidance in connection with the annual impairment testing of its indefinite-lived intangible assets, which is performed annually in the fourth quarter based on data as of September 30. This guidance does not affect existing guidance on recognition or measurement of impairment losses on indefinite-lived intangible assets, and as such it will not affect the Company’s financial position, results of operations or cash flows.
	In February 2013, the FASB issued amended guidance on the presentation of amounts reclassified out of accumulated other comprehensive income in one place, either on the face of the income statement or in the footnotes to the financial statements. The Company adopted this guidance effective January 1, 2013 on a prospective basis as prescribed by the amended guidance. As all of the information that this guidance requires to be disclosed is already presented elsewhere in the Company’s financial statements under existing GAAP, and it does not affect the classification, recognition or measurement of items within other comprehensive income, the adoption will not affect the Company’s financial position, results of operations or cash flows.
Accounting guidance not yet effective	'
	Accounting guidance not yet effective
	In July 2013, the FASB issued new guidance that permits the use of a new benchmark for hedges. This guidance is effective prospectively for new or re-designated hedges as of July 17, 2013. The Company will consider this guidance if and when it enters into any new hedging relationships.
Accounting for the Merger Transaction	'
	Accounting for the Merger Transaction
	The Company has accounted for the Merger Transaction as a reverse acquisition in which TGI, the legal acquiree, was identified and treated as the accounting acquirer and Tower Group International, Ltd., the legal acquirer, was identified and treated as the accounting acquiree. The identification of the accounting acquirer and acquiree in the Merger Transaction was primarily based on the fact that immediately following the close of the Merger Transaction there was a change in control of the Company with TGI designees to the Company’s Board of Directors comprising all of its directors and TGI’s former senior management comprising the Company’s entire senior management team. In accordance with accounting guidance for reverse acquisitions, the unaudited consolidated financial statements of the Company following the Merger Transaction have been issued under the name of the Company, as the legal parent, but reflect a continuation of the financial statements of TGI, as the accounting acquirer, with one exception, which was the retroactive adjustment of TGI’s historical legal capital to reflect the transaction as a recapitalization of TGI’s historical capital accounts. On the effective date of the Merger Transaction, the assets and liabilities of Tower Group International, Ltd. were accounted for under the acquisition method, under which they have been reflected at their respective acquisition date fair values.
	Prior to the Merger Transaction, Canopius Bermuda restructured its insurance operations as contemplated in the Master Transaction Agreement. This restructuring occurred primarily through the execution of retrocession agreements with Canopius Reinsurance Limited (“CRL”), an indirectly wholly-owned subsidiary of Canopius Group, to retrocede a percentage of Lloyd’s of London Syndicate 4444 (“Syndicate 4444”) business for the Year of Account (“YOA”) 2012, YOA 2011 and prior years, which Canopius Bermuda assumed from Canopius Group. Syndicate 4444 is an insurance syndicate managed by Canopius Group. The Company accounts for these retrocession agreements in accordance with prospective accounting treatment, and reports the assumed and ceded assets and liabilities on a gross basis on the consolidated balance sheet. On September 30, 2013, Tower commuted the Syndicate 4444 YOA 2012 and YOA 2011 and prior years retrocession agreements with CRL and novated the assumed reinsurance with Canopius Group on these same contracts.
	In addition, effective January 1, 2013, pursuant to the terms of the Master Transaction Agreement, prior to the Merger Transaction, TGI entered into a commutation agreement whereby the TGI commuted Syndicate 4444 YOA 2012 and YOA 2011 business TGI previously reinsured from Canopius Group in prior years. There was no gain or loss recognized on this commutation.
Goodwill Impairment Testing and Charge	'
	Goodwill Impairment Testing and Charge
	The Company tests goodwill balances for impairment annually in the fourth quarter of each year using a September 30 measurement date, or more frequently if circumstances indicate that the value of goodwill may be impaired. Goodwill impairment is performed at the reporting unit level and the test requires a two-step process. In performing Step 1of the impairment test, management compared the estimated fair values of the applicable reporting units to their aggregate carrying values, including goodwill. If the carrying amount of a reporting unit including goodwill were to exceed the fair value of the reporting unit, Step 2 of the goodwill impairment would be performed. Step 2 of the goodwill impairment test requires comparing the implied fair value of the affected reporting unit’s goodwill against the carrying value of that goodwill.
	In its 2012 annual impairment test, management determined that a greater risk of future impairment existed for the Commercial Insurance reporting unit. During the second quarter of 2013, management concluded an impairment test was required as a result of the significant prior years’ loss reserves incurred (see “Note 9 – Loss and Loss Adjustment Expense”) and the 2013 reorganization.
	In conducting the goodwill impairment analysis as of June 30, 2013, the Company tested the reporting units prior to the reorganization as required by GAAP. The Company estimated each of the reporting units’ fair values using a market multiple approach based on tangible book values. Historically, the Company also utilized market multiple approaches based on (i) book value, (ii) estimates of projected results for future periods, and (iii) a valuation technique using discounted cash flows. However, based upon the significance of the loss reserve charge recorded in the second quarter of 2013, the reduction to Tower’s insurance subsidiaries’ capital and surplus levels (see “Note 16 – Statutory Financial Information”), management in its judgment concluded a multiple of tangible book value was most indicative of a price a market participant would pay for the reporting units. In addition, the Commercial Insurance reporting unit’s estimated fair value was adjusted for the expected capital infusion a market participant would be expected to fund into the insurance businesses to maintain historical rating agency ratings.
	Step 1 of the impairment test indicated the Commercial Insurance unit’s carrying value exceeded its fair value and the Personal Insurance unit’s fair value exceeded its carrying value.
	Accordingly, the Company performed a Step 2 impairment test on the Commercial Insurance reporting unit. Based on the results, the Company recorded a non-cash goodwill impairment charge of $214.0 million to write-down all of the goodwill in the Commercial Insurance reporting unit as of June 30, 2013.
Variable Interest Entities	'
	The Company determined that each of the Reciprocal Exchanges qualifies as a VIE and that the Company is the primary beneficiary as it has both the power to direct the activities of the Reciprocal Exchanges that most significantly impact their economic performance and the risk of economic loss through its ownership of the surplus notes. Accordingly, the Company consolidates these Reciprocal Exchanges and eliminates all intercompany balances and transactions with Tower.
Impairment Review	'
	Impairment Review
	Management regularly reviews the Company’s fixed-maturity and equity security portfolios in accordance with its impairment policy to evaluate the necessity of recording impairment losses for OTTI. The determination of OTTI is a subjective process and different judgments and assumptions could affect the timing of loss realization.
	Management, in conjunction with its outside portfolio managers, analyzes its non-agency residential mortgage-backed securities (“RMBS”) using default loss models based on the performance of the underlying loans. Performance metrics include delinquencies, defaults, foreclosures, anticipated cash flow prepayments and cumulative losses incurred. The expected losses for a mortgage pool are compared to the break-even loss, which represents the point at which the Company’s tranche begins to experience losses.
	The commercial mortgage-backed securities (“CMBS”) holdings are evaluated using analytical techniques and various metrics including the level of subordination, debt-service-coverage ratios, loan-to-value ratios, delinquencies, defaults and foreclosures.
	For the non-structured fixed-maturity securities (U.S. Treasury and Agency securities, municipal bonds, and corporate debt), unrealized losses are reviewed to determine whether full recovery of principal and interest will be received. The estimate of expected cash flows is determined by projecting a recovery value and a recovery time frame and assessing whether further principal and interest will be received. The determination of recovery value incorporates an issuer valuation assumption utilizing one or a combination of valuation methods as deemed appropriate by management. The present value of the cash flows is determined by applying the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment) and an estimated recovery time frame. For securities for which the issuer is financially troubled but not in bankruptcy, that time frame is generally longer. Included in the present value calculation are expected principal and interest payments; however, for securities for which the issuer is classified as bankrupt or in default, the present value calculation assumes no interest payments and a single recovery amount. In situations for which a present value of cash flows cannot be estimated, a write-down to fair value is recorded.
	In estimating the recovery value, significant judgment is involved in the development of assumptions relating to a number of factors related to the issuer including, but not limited to, revenue, margin and earnings projections, the likely market or liquidation values of assets, potential additional debt to be incurred pre- or post- bankruptcy/restructuring, the ability to shift existing or new debt to different priority layers, the amount of restructuring/bankruptcy expenses, the size and priority of unfunded pension obligations, litigation or other contingent claims, the treatment of intercompany claims and the likely outcome with respect to inter-creditor conflicts.
	The evaluation of equity securities includes management’s intent and ability to hold the security to recovery. Management will record OTTI in those situations where it does not intend to hold the security to recovery or if the security is not expected to recover in value in the near term.
Fair Value Measurements	'
	GAAP establishes a three-level hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). If the inputs used to measure the assets or liabilities fall within different levels of the hierarchy, the classification is based on the lowest level input that is significant to the fair value measurement of the asset or liability. Classification of assets and liabilities within the hierarchy considers the markets in which the assets and liabilities are traded, including during periods of market disruption, and the reliability and transparency of the assumptions used to determine fair value. The hierarchy requires the use of observable market data when available. The levels of the hierarchy are as follows:
	Level 1 — Inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities traded in active markets. Included are those equity securities that are traded on active exchanges, such as the NASDAQ Global Select Market.
	Level 2 — Inputs to the valuation methodology include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability and market-corroborated inputs. Included are investments in U.S. Treasury and Agency securities and, together with municipal bonds, corporate debt securities, commercial mortgages, residential mortgage-backed securities and asset-backed securities. Additionally, interest-rate swap contracts utilize Level 2 inputs in deriving fair values.
	Level 3 — Inputs to the valuation methodology are unobservable in the market for the asset or liability and are significant to the fair value measurement. Material assumptions and factors considered in pricing investment securities may include projected cash flows, collateral performance including delinquencies, defaults and recoveries, and any market clearing activity or liquidity circumstances in the security or similar securities that may have occurred since the prior pricing period.
Earnings (Loss) Per Share	'
	Undistributed net earnings (net income less dividends declared during the period) are allocated to both common stock and unvested share-based payment awards (“unvested restricted stock”). Because the common shareholders and unvested restricted stock holders share in dividends on a 1:1 basis, the earnings per share on undistributed earnings is equivalent, however, undistributed losses are allocated only to common stock holders. Undistributed earnings are allocated to all outstanding share-based payment awards, including those for which the requisite service period is not expected to be rendered.
Segment Information	'
	The accounting policies of the segments are the same as those described in TGI’s summary of significant accounting policies in its Amendment No. 2 to the Annual Report on Form 10-K for the year ended December 31, 2012.
	As disclosed in “Note 1 – Nature of Business”, the Company revised its business segments to present Commercial Insurance, Specialty Insurance and Reinsurance and Personal Insurance segments. The Company has restated prior period segments to be consistent with the current presentation.
	Segment performance is evaluated based on segment profit, which excludes investment income, realized gains and losses, interest expense, income taxes and corporate expenses. Intangibles and goodwill are allocated to each of the segments. All other assets are not allocated to segments because the other assets are considered in total by management for decision-making purposes.
	The Personal Insurance segment, which includes the Reciprocal Exchanges and the management companies, reports the management fees earned by Tower from the Reciprocal Exchanges for underwriting, investment management and other services as a reduction to other underwriting expenses. The effects of these management fees between Tower and the Reciprocal Exchanges are eliminated in consolidation to derive consolidated net income. However, the management fee income is reported in net income attributable to Tower Group International, Ltd. and included in basic and diluted earnings (loss) per share.

Restatement_of_Previously_Issu1

Restatement of Previously Issued Financial Statements (Tables)	6 Months Ended
	Jun. 30, 2013
Restatement on Consolidated Balance Sheets	'
	The effect of the restatement on the consolidated balance sheets are presented in the table below:
		December 31, 2012
	($ in thousands, except par value and share amounts)	As			Restated			Effect of
		Previously						Adjustments
		Reported
	Assets
	Total investments		2,554,505			2,553,505			(1,000	)
	Cash and cash equivalents		100,293			102,269			1,976
	Investment income receivable		25,332			25,332			—
	Investment in unconsolidated affiliate		70,830			71,894			1,064
	Premiums receivable		422,112			412,045			(10,067	)
	Reinsurance recoverable on paid losses		17,609			17,609			—
	Reinsurance recoverable on unpaid losses		496,192			459,457			(36,735	)
	Prepaid reinsurance premiums		63,923			63,923			—
	Deferred acquisition costs, net		180,941			181,198			257
	Intangible assets		106,768			106,768			—
	Goodwill		241,458			241,458			—
	Funds held by reinsured companies		137,545			137,545			—
	Other assets		331,506			338,769			7,263
	Total Assets		4,749,014		$	4,711,772		$	(37,242	)
	Liabilities
	Loss and loss adjustment expenses		1,895,073		$	1,895,679		$	606
	Unearned premium		920,859			921,271			412
	Reinsurance balances payable		40,569			40,569			—
	Funds held under reinsurance agreements		98,581			98,581			—
	Other liabilities		292,239			296,960			4,721
	Deferred income taxes		36,464			24,763			(11,701	)
	Debt		449,731			449,731			—
	Total liabilities		3,733,516			3,727,554			(5,962	)
	Contingencies		—			—			—
	Stockholders’ equity
	Common stock		530			530			—
	Treasury stock		(181,435	)		(181,435	)		—
	Paid-in-capital		780,036			780,036			—
	Accumulated other comprehensive income		83,406			82,756			(650	)
	Retained earnings		298,299			268,171			(30,128	)
	Tower Group, Inc. stockholders’ equity		980,836			950,058			(30,778	)
	Noncontrolling interests		34,662			34,160			(502	)
	Total stockholders’ equity		1,015,498			984,218			(31,280	)
	Total liabilities and stockholders’ equity		4,749,014		$	4,711,772		$	(37,242	)

Accounting_Policies_and_Basis_2

Accounting Policies and Basis of Presentation (Tables)	6 Months Ended
	Jun. 30, 2013
Reflects Previously Reported and Revised Shareholders' Equity Accounts Resulting from Merger Transaction	'
	The table below reflects the previously reported and revised shareholders’ equity accounts resulting from the Merger Transaction:
		As previously			Revised
	($ in thousands, except per share amounts)	Reported			Amount
	As of December 31, 2012
	Common stock	$	469		$	530
	Treasury stock		(181,435	)		(181,435	)
	Paid-in-capital		780,097			780,036
	For the three-months ended June 30, 2012
	Earnings (Loss) per Share:
	Basic	$	(0.43	)	$	(0.39	)
	Diluted		(0.43	)		(0.39	)
	Weighted average common shares outstanding
	Basic		39,117			43,289
	Diluted		39,117			43,289
	For the six-months ended June 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.06		$	0.05
	Diluted		0.06			0.05
	Weighted average common shares outstanding
	Basic		39,206			43,340
	Diluted		39,268			43,410

Merger_Transaction_Tables

Merger Transaction (Tables)	6 Months Ended
	Jun. 30, 2013
Preliminary Purchase Consideration	'
	The purchase consideration was determined based on the total consideration received by Canopius Group for its sale of 100% of its equity ownership of Canopius Bermuda, and the proceeds received for the issuance and exercise of the Merger Option from TGI.
	(in thousands)
	Consideration received by Canopius Group from the third party sale	$	205,863
	Fair value of Merger Option received in connection with TGI’s investment in Canopius Group		484
	Exercise price of Merger Right received from TGI upon exercise		1,000
	Total preliminary purchase consideration	$	207,347
Fair Values of Respective Assets Acquired and Liabilities Assumed	'
	($ in thousands)
	Assets
	Cash and cash equivalents	$	134,741
	Investments		26,485
	Reinsurance recoverables		468,727
	Prepaid reinsurance		152,431
	Funds held by reinsured companies		698,819
	Other assets		75,219
	Liabilities
	Loss and loss adjustment expenses		630,613
	Unearned premiums		169,963
	Funds held under reinsurance agreements		560,714
	Other liabilities		15,916
	Net assets acquired	$	179,216
	Purchase Consideration		207,347
	Goodwill	$	28,131
Pro Forma Financial Information	'
	These pro forma amounts exclude any pro forma impacts to the Company’s effective federal income tax rates.
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Revenues	$	460,518		$	509,666		$	940,145		$	979,033
	Net Income (Loss)		(505,876	)		(16,887	)		(485,248	)		10,074

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2013
Summary of Goodwill by Reporting Units	'
	The following table reflects the changes to goodwill during 2013 and is presented using the reporting units prior to the reorganization.
	($ in thousands)	Commercial			Personal		Total
		Insurance			Insurance
	Balance, January 1, 2013	$	185,918		$	55,540	$	241,458
	Goodwill from Merger Transaction		28,131			-		28,131
	Goodwill impairment		(214,049	)		-		(214,049	)
	Total, June 30, 2013	$	-		$	55,540	$	55,540

Investments_Tables

Investments (Tables)	6 Months Ended
	Jun. 30, 2013
Summary of Cost or Amortized Cost and Fair Value of Investments in Fixed Maturity and Equity Securities, Gross Unrealized Gains and Losses, and Other-Than-Temporary Impairment Losses	'
	The cost or amortized cost and fair value of the Company’s investments in fixed maturity and equity securities, gross unrealized gains and losses, and other-than-temporary impairment losses (“OTTI”) as of June 30, 2013 and December 31, 2012 are summarized as follows:
	($ in thousands)	Cost or			Gross			Gross			Fair Value			Unrealized
		Amortized			Unrealized			Unrealized						OTTI
		Cost			Gains			Losses						Losses (1)
	June 30, 2013
	U.S. Treasury securities	$	390,003		$	1,024		$	(5,780	)	$	385,247		$	-
	U.S. Agency securities		104,099			2,189			(965	)		105,323			-
	Municipal bonds		568,991			24,132			(5,732	)		587,391			(71	)
	Corporate and other bonds
	Finance		246,779			14,594			(4,240	)		257,133			-
	Industrial		406,976			13,171			(5,675	)		414,472			-
	Utilities		58,368			2,078			(2,152	)		58,294			(203	)
	Commercial mortgage-backed securities		217,531			21,439			(2,351	)		236,619			(604	)
	Residential mortgage-backed securities
	Agency backed securities		161,783			4,891			(1,614	)		165,060			-
	Non-agency backed securities		35,583			4,059			(30	)		39,612			(6	)
	Asset-backed securities		39,294			1,102			(2	)		40,394			-
	Total fixed-maturity securities		2,229,407			88,679			(28,541	)		2,289,545			(884	)
	Preferred stocks, principally financial sector		21,584			188			(1,137	)		20,635			-
	Common stocks, principally financial and industrial sectors		108,765			8,463			(463	)		116,765			-
	Short-term investments		13,415			-			(36	)		13,379			-
	Total, June 30, 2013	$	2,373,171		$	97,330		$	(30,177	)	$	2,440,324		$	(884	)
	Tower	$	2,121,665		$	87,920		$	(25,786	)	$	2,183,799		$	(884	)
	Reciprocal Exchanges		251,506			9,410			(4,391	)		256,525			-
	Total, June 30, 2013	$	2,373,171		$	97,330		$	(30,177	)	$	2,440,324		$	(884	)
	December 31, 2012, as restated
	U.S. Treasury securities	$	183,462		$	1,500		$	(13	)	$	184,949		$	-
	U.S. Agency securities		98,502			4,351			(76	)		102,777			-
	Municipal bonds		633,373			52,914			(244	)		686,043			-
	Corporate and other bonds
	Finance		233,849			21,293			(1,095	)		254,047			-
	Industrial		412,465			26,556			(868	)		438,153			-
	Utilities		51,698			2,958			(191	)		54,465			-
	Commercial mortgage-backed securities		211,819			30,375			(141	)		242,053			-
	Residential mortgage-backed securities
	Agency backed securities		283,652			12,326			(262	)		295,716			-
	Non-agency backed securities		38,615			3,575			(34	)		42,156			(6	)
	Asset-backed securities		42,751			1,615			(14	)		44,352			-
	Total fixed-maturity securities		2,190,186			157,463			(2,938	)		2,344,711			(6	)
	Preferred stocks, principally financial sector		31,272			730			(481	)		31,521			-
	Common stocks, principally industrial and financial sectors		118,076			953			(4,292	)		114,737			-
	Short-term investments		4,749			1			-			4,750			-
	Total, December 31, 2012, as restated	$	2,344,283		$	159,147		$	(7,711	)	$	2,495,719		$	(6	)
	Tower	$	2,075,189		$	141,614		$	(7,210	)	$	2,209,593		$	(6	)
	Reciprocal Exchanges		269,094			17,533			(501	)		286,126			-
	Total, December 31, 2012, as restated	$	2,344,283		$	159,147		$	(7,711	)	$	2,495,719		$	(6	)
	(1) Represents the gross unrealized loss on other-than-temporarily impaired securities recognized in accumulated other comprehensive income (loss).
Summary of Major Categories of Net Investment Income	'
	Major categories of net investment income are summarized as follows:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Income
	Fixed-maturity securities	$	20,562		$	24,511		$	41,535		$	49,924
	Equity securities		6,808			6,603			13,292			14,239
	Cash and cash equivalents		19			505			70			798
	Other invested assets		2,158			1,313			6,414			3,146
	Other		287			203			615			349
	Total		29,834			33,135			61,926			68,456
	Expenses
	Investment expenses		(1,432	)		(1,354	)		(3,207	)		(2,732	)
	Net investment income	$	28,402		$	31,781		$	58,719		$	65,724
	Tower		27,612			30,267			57,195			62,525
	Reciprocal Exchanges		2,458			3,177			4,839			6,526
	Elimination of interest on Reciprocal Exchange surplus notes		(1,668	)		(1,663	)		(3,315	)		(3,327	)
	Net investment income	$	28,402		$	31,781		$	58,719		$	65,724
Summary of Gross Realized Gains, Losses and Impairment Write-Downs on Investments	'
	Gross realized gains, losses and impairment write-downs on investments are summarized as follows:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Fixed-maturity securities
	Gross realized gains	$	10,479		$	12,354		$	17,843		$	25,162
	Gross realized losses		(1,672	)		(609	)		(1,862	)		(2,551	)
			8,807			11,745			15,981			22,611
	Equity securities
	Gross realized gains		5,323			2,685			9,559			4,179
	Gross realized losses		(12,717	)		(9,808	)		(17,530	)		(16,160	)
			(7,394	)		(7,123	)		(7,971	)		(11,981	)
	Other
	Gross realized gains		2,100			555			3,855			1,790
	Gross realized losses		(1,091	)		(3,174	)		(1,903	)		(4,113	)
			1,009			(2,619	)		1,952			(2,323	)
	Net realized gains (losses) on investments		2,422			2,003			9,962			8,307
	Other-than-temporary impairment losses:
	Fixed-maturity securities		(23	)		(765	)		(187	)		(882	)
	Equity securities		(4,433	)		(1,219	)		(4,958	)		(4,078	)
	Total other-than-temporary impairment losses recognized in earnings		(4,456	)		(1,984	)		(5,145	)		(4,960	)
	Total net realized investment gains (losses)	$	(2,034	)	$	19		$	4,817		$	3,347
	Tower	$	(2,243	)	$	(110	)	$	3,990		$	1,028
	Reciprocal Exchanges		209			129			827			2,319
	Total net realized investment gains (losses)	$	(2,034	)	$	19		$	4,817		$	3,347
Amount of Fixed-Maturity and Equity Securities that were Other-Than-Temporary Impairment	'
	The following table shows the fixed-maturity and equity securities OTTI amounts for the three and six months ended June 30, 2013 and 2012:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Corporate and other bonds	$	-		$	(648	)	$	-		$	(737	)
	Commercial mortgage-backed securities		(23	)		(403	)		(47	)		(403	)
	Residential mortgage-backed securities		(140	)		-			(140	)		(28	)
	Equities		(4,293	)		(1,219	)		(4,958	)		(4,078	)
	Other-than-temporary-impairments		(4,456	)		(2,270	)		(5,145	)		(5,246	)
	Portion of loss recognized in accumulated other comprehensive income (loss)		-			286			-			286
	Impairment losses recognized in earnings	$	(4,456	)	$	(1,984	)	$	(5,145	)	$	(4,960	)
	Tower	$	(4,456	)	$	(1,984	)	$	(5,145	)	$	(4,960	)
	Reciprocal Exchanges		-			-			-			-
	Impairment losses recognized in earnings	$	(4,456	)	$	(1,984	)	$	(5,145	)	$	(4,960	)
Rollforward of Cumulative Amount of Other-Than-Temporary Impairment for Securities Still Held Showing Amounts that have been Included in Earnings on Pretax Basis	'
	The following table provides a rollforward of the cumulative amounts of credit OTTI for securities still held showing the amounts that have been included in earnings on a pretax basis for the three months ended June 30, 2013 and 2012:
		Three Months Ended
		June 30,
	($ in thousands)	2013			2012
	Balance, April 1,	$	4,516		$	6,084
	Additional credit losses recognized during the period, related to securities for which:
	No OTTI has been previously recognized		23			765
	OTTI has been previously recognized		-			-
	Reductions due to:
	Securities sold during the period (realized)		-			(730	)
	Balance, June 30,	$	4,539		$	6,119
	The following table provides a rollforward of the cumulative amounts of credit OTTI for securities still held showing the amounts that have been included in earnings on a pretax basis for the six months ended June 30, 2013 and 2012:
		Six Months Ended
		June 30,
	($ in thousands)	2013			2012
	Balance, January 1,	$	4,492		$	12,666
	Additional credit losses recognized during the period, related to securities for which:
	No OTTI has been previously recognized		47			854
	OTTI has been previously recognized		-			28
	Reductions due to:
	Securities sold during the period (realized)		-			(7,429	)
	Balance, June 30,	$	4,539		$	6,119
Information Regarding Invested Assets that were in Unrealized Loss Position	'
	The following table presents information regarding invested assets that were in an unrealized loss position at June 30, 2013 and December 31, 2012 by amount of time in a continuous unrealized loss position:
		Less than 12 Months						12 Months or Longer						Total
		Fair			Unrealized			Fair			Unrealized			Aggregate			Unrealized
	($ in thousands)	Value			Losses			Value			Losses			Fair Value			Losses
	June 30, 2013
	U.S. Treasury securities	$	318,415		$	(5,780	)	$	-		$	-		$	318,415		$	(5,780	)
	U.S. Agency securities		32,802			(965	)		-			-			32,802			(965	)
	Municipal bonds		151,394			(5,688	)		218			(44	)		151,612			(5,732	)
	Corporate and other bonds
	Finance		76,192			(4,240	)		-			-			76,192			(4,240	)
	Industrial		188,193			(5,635	)		1,184			(40	)		189,377			(5,675	)
	Utilities		42,328			(2,152	)		-			-			42,328			(2,152	)
	Commercial mortgage-backed securities		50,984			(2,351	)		-			-			50,984			(2,351	)
	Residential mortgage-backed securities
	Agency backed		54,462			(1,613	)		229			(1	)		54,691			(1,614	)
	Non-agency backed		639			(16	)		199			(14	)		838			(30	)
	Asset-backed securities		2,507			(2	)		-			-			2,507			(2	)
	Total fixed-maturity securities		917,916			(28,442	)		1,830			(99	)		919,746			(28,541	)
	Preferred stocks		9,802			(821	)		6,089			(316	)		15,891			(1,137	)
	Common stocks		44,338			(463	)		-			-			44,338			(463	)
	Short-term investments		11,379			(36	)		-			-			11,379			(36	)
	Total, June 30, 2013	$	983,435		$	(29,762	)	$	7,919		$	(415	)	$	991,354		$	(30,177	)
	Tower	$	875,960		$	(25,386	)	$	7,553		$	(400	)	$	883,513		$	(25,786	)
	Reciprocal Exchanges		107,475			(4,376	)		366			(15	)		107,841			(4,391	)
	Total, June 30, 2013	$	983,435		$	(29,762	)	$	7,919		$	(415	)	$	991,354		$	(30,177	)
	December 31, 2012, as restated
	U.S. Treasury securities	$	44,347		$	(13	)	$	-		$	-		$	44,347		$	(13	)
	U.S. Agency securities		22,345			(76	)		-			-			22,345			(76	)
	Municipal bonds		21,532			(235	)		251			(9	)		21,783			(244	)
	Corporate and other bonds
	Finance		16,853			(1,095	)		-			-			16,853			(1,095	)
	Industrial		53,576			(666	)		4,188			(202	)		57,764			(868	)
	Utilities		20,143			(191	)		7			-			20,150			(191	)
	Commercial mortgage-backed securities		23,223			(141	)		95			-			23,318			(141	)
	Residential mortgage-backed securities
	Agency backed		59,009			(261	)		25			(1	)		59,034			(262	)
	Non-agency backed		815			(6	)		588			(28	)		1,403			(34	)
	Asset-backed securities		1,499			(3	)		4,232			(11	)		5,731			(14	)
	Total fixed-maturity securities		263,342			(2,687	)		9,386			(251	)		272,728			(2,938	)
	Preferred stocks		9,716			(155	)		5,724			(326	)		15,440			(481	)
	Common stocks		55,560			(4,292	)		-			-			55,560			(4,292	)
	Total, December 31, 2012, as restated	$	328,618		$	(7,134	)	$	15,110		$	(577	)	$	343,728		$	(7,711	)
	Tower	$	270,609		$	(6,732	)	$	13,338		$	(478	)	$	283,947		$	(7,210	)
	Reciprocal Exchanges		58,009			(402	)		1,772			(99	)		59,781			(501	)
	Total, December 31, 2012, as restated	$	328,618		$	(7,134	)	$	15,110		$	(577	)	$	343,728		$	(7,711	)
Amortized Cost and Fair Value of Fixed-Maturity Portfolio by Contractual Time to Maturity	'
	The following table shows the amortized cost and fair value of the fixed-maturity portfolio by contractual time to maturity at June 30, 2013 and December 31, 2012:
		Tower						Reciprocal Exchanges						Total
	($ in thousands)	Amortized			Fair Value			Amortized			Fair			Amortized			Fair Value
		Cost						Cost			Value			Cost
	June 30, 2013
	Remaining Time to Maturity
	Less than one year	$	38,967		$	39,597		$	3,996		$	4,148		$	42,963		$	43,745
	One to five years		614,572			626,489			41,860			43,790			656,432			670,279
	Five to ten years		646,016			654,732			66,201			65,527			712,217			720,259
	More than 10 years		301,473			310,890			62,131			62,685			363,604			373,575
	Mortgage and asset-backed securities		379,624			404,062			74,567			77,625			454,191			481,687
	Total, June 30, 2013	$	1,980,652		$	2,035,770		$	248,755		$	253,775		$	2,229,407		$	2,289,545
	December 31, 2012, as restated
	Remaining Time to Maturity
	Less than one year	$	30,082		$	30,614		$	2,678		$	2,715		$	32,760		$	33,329
	One to five years		489,939			510,523			45,576			47,275			535,515			557,798
	Five to ten years		564,556			607,711			76,480			80,009			641,036			687,720
	More than 10 years		346,410			379,045			57,628			62,542			404,038			441,587
	Mortgage and asset-backed securities		495,249			536,255			81,588			88,022			576,837			624,277
	Total, December 31, 2012, as restated	$	1,926,236		$	2,064,148		$	263,950		$	280,563		$	2,190,186		$	2,344,711
Composition of Other Invested Assets	'
	The following table shows the composition of the other invested assets as of June 30, 2013 and December 31, 2012:
		June 30,			December 31,
	($ in thousands)	2013			2012
	Limited partnerships, equity method	$	34,843		$	23,864
	Real estate, amortized cost		7,645			7,422
	Securities reported under the fair value option		30,250			25,000
	Other		4,300			1,500
	Total	$	77,038		$	57,786

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2013
Financial Instruments at Fair Value among Levels	'
	As at June 30, 2013 and December 31, 2012, the Company’s financial instruments carried at fair value are allocated among levels as follows:
	($ in thousands)	Level 1		Level 2			Level 3		Total
	June 30, 2013
	Fixed-maturity securities
	U.S. Treasury securities	$	-	$	385,247		$	-	$	385,247
	U.S. Agency securities		-		105,323			-		105,323
	Municipal bonds		-		587,391			-		587,391
	Corporate and other bonds		-		729,899			-		729,899
	Commercial mortgage-backed securities		-		236,619			-		236,619
	Residential mortgage-backed securities
	Agency		-		165,060			-		165,060
	Non-agency		-		39,612			-		39,612
	Asset-backed securities		-		40,394			-		40,394
	Total fixed-maturities		-		2,289,545			-		2,289,545
	Equity securities		137,400		-			-		137,400
	Short-term investments		-		13,379			-		13,379
	Total investments at fair value		137,400		2,302,924			-		2,440,324
	Other invested assets (1)		-		-			30,250		30,250
	Other liabilities									-
	Interest rate swap contracts		-		(6,830	)		-		(6,830	)
	Debt and equity securities sold, not yet purchased		-		(25,570	)		-		(25,570	)
	Total, June 30, 2013	$	137,400	$	2,270,524		$	30,250	$	2,438,174
	Tower	$	134,650	$	2,016,748		$	30,250	$	2,181,648
	Reciprocal Exchanges		2,750		253,776			-		256,526
	Total, June 30, 2013	$	137,400	$	2,270,524		$	30,250	$	2,438,174
	December 31, 2012, as restated
	Fixed-maturity securities
	U.S. Treasury securities	$	-	$	184,949		$	-	$	184,949
	U.S. Agency securities		-		102,777			-		102,777
	Municipal bonds		-		686,043			-		686,043
	Corporate and other bonds		-		746,665			-		746,665
	Commercial mortgage-backed securities		-		242,053			-		242,053
	Residential mortgage-backed securities
	Agency		-		295,716			-		295,716
	Non-agency		-		42,156			-		42,156
	Asset-backed securities		-		44,352			-		44,352
	Total fixed-maturities		-		2,344,711			-		2,344,711
	Equity securities		146,258		-			-		146,258
	Short-term investments		-		4,750			-		4,750
	Total investments at fair value		146,258		2,349,461			-		2,495,719
	Other invested assets (2)		-		-			25,000		25,000
	Other liabilities
	Interest rate swap contracts		-		(9,016	)		-		(9,016	)
	Debt and equity securities sold, not yet purchased		-		(17,101	)		-		(17,101	)
	Total, December 31, 2012, as restated	$	146,258	$	2,323,344		$	25,000	$	2,494,602
	Tower	$	140,695	$	2,042,780		$	25,000	$	2,208,475
	Reciprocal Exchanges		5,563		280,564			-		286,127
	Total, December 31, 2012, as restated	$	146,258	$	2,323,344		$	25,000	$	2,494,602
	(1) $30.3 million of the $77.0 million Other invested assets reported on the consolidated balance sheet at June 30, 2013 is reported at fair value. The remaining $46.7 million of Other invested assets is reported under the equity method of accounting or at amortized cost.
	(2) $25.0 million of the $57.8 million Other invested assets reported on the consolidated balance sheet at December 31, 2012 is reported at fair value. The remaining $32.8 million of Other invested assets is reported under the equity method of accounting or at amortized cost.
Summary of Changes in Level Three Assets Measured at Fair Value	'
	The following table summarizes the changes in Level 3 assets measured at fair value for the three months ended June 30, 2013 and 2012 for Tower (the Reciprocal Exchanges have no Level 3 assets):
				Three Months Ended
				June 30,
	($ in thousands)			2013			2012
	Beginning balance, April 1,		$		25,000		$	24,914
	Total gains (losses)-realized / unrealized
	Included in net income				-			86
	Included in other comprehensive income (loss)				-			-
	Purchases, issuances and settlements				5,250			-
	Net transfers into (out of) Level 3				-			-
	Ending balance, June 30,	$			30,250		$	25,000
	The following table summarizes the changes in Level 3 assets measured at fair value for the six months ended June 30, 2013 and 2012 for Tower (the Reciprocal Exchanges have no Level 3 assets):
				Six Months Ended
				June 30,
	($ in thousands)			2013			2012
	Beginning balance, January 1	$			25,000		$	25,000
	Total gains (losses)-realized / unrealized - included in net income				-			-
	Included in other comprehensive income (loss)				-			-
	Purchases, issuances and settlements				5,250			-
	Net transfers into (out of) Level 3				-			-
	Ending balance, June 30,	$			30,250		$	25,000

Loss_and_Loss_Adjustment_Expen1

Loss and Loss Adjustment Expense (Tables)	6 Months Ended
	Jun. 30, 2013
Reconciliation of Beginning and Ending Consolidated Balances for Unpaid Losses and Loss Adjustment Expense	'
	The following table provides a reconciliation of the beginning and ending consolidated balances for unpaid losses and loss adjustment expense (“LAE”) for the six months ended June 30, 2013 and 2012:
		Six Months Ended June 30,
		2013									2012
	($ in thousands)	Tower			Reciprocal			Total			Tower			Reciprocal			Total
					Exchanges									Exchanges
	Balance at January 1, as restated	$	1,759,888		$	135,791		$	1,895,679		$	1,495,839		$	136,274		$	1,632,113
	Less reinsurance recoverables on unpaid losses		(407,068	)		(52,389	)		(459,457	)		(280,968	)		(11,253	)		(292,221	)
			1,352,820			83,402			1,436,222			1,214,871			125,021			1,339,892
	Net reserves, at fair value, of acquired entities		161,886			-			161,886			-			-			-
	Incurred related to:
	Current year		451,020			57,688			508,708			487,837			57,430			545,267
	Prior years unfavorable/(favorable) development		326,749			167			326,916			78,254			(6,253	)		72,001
	Total incurred		777,769			57,855			835,624			566,091			51,177			617,268
	Paid related to:
	Current year		164,774			36,669			201,443			153,792			31,369			185,161
	Prior years		359,786			10,221			370,007			313,400			30,943			344,343
	Total paid		524,560			46,890			571,450			467,192			62,312			529,504
	Net balance at end of period		1,767,915			94,367			1,862,282			1,313,770			113,886			1,427,656
	Add reinsurance recoverables on unpaid losses		665,172			24,897			690,069			254,516			19,661			274,177
	Balance at June 30,	$	2,433,087		$	119,264		$	2,552,351		$	1,568,286		$	133,547		$	1,701,833

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2013
Summary of Changes in Accumulated Other Comprehensive Income	'
	The following table provides a summary of changes in accumulated other comprehensive income, by component, for the six months ended June 30, 2013, with all amounts reflected net of income taxes and noncontrolling interest:
	($ in thousands)	Unrealized			Gains		Cumulative			Total
		gains (losses)			(losses) on		translation
		on available for			cash flow		adjustments
		sale securities			hedges
	Balance at December 31, 2012, as restated	$	87,412		$	-5,860	$	1,204		$	82,756
	Other comprehensive income before reclassifications, net of tax		(71,210	)		1,406		(2,382	)		(72,186	)
	Amounts reclassified from accumulated other comprehensive income, net of tax		(2,594	)		1,084		-			(1,510	)
	Net current period other comprehensive income		(73,804	)		2,490		(2,382	)		(73,696	)
	Balance at June 30, 2013	$	13,608		$	-3,370	$	(1,178	)	$	9,060
Reclassified from Accumulated Other Comprehensive Income to Net Income	'
	The following provides a summary of the items that have been reclassified from accumulated other comprehensive income to net income in their entirety during the six months ended June 30, 2013, including the line item on the consolidated statement of operations on which the impact is reflected. Unrealized gains (losses) on available for sale securities are reclassified from accumulated other comprehensive income when a security is sold or when a non-credit impairment is recorded. Gains (losses) on cash flow hedges are reclassified from accumulated other comprehensive income when the related hedged item (subordinated debentures floating rate interest payments) are recorded in the statement of operations.
	($ in thousands)
	Accumulated other comprehensive income components	Amounts reclassified			Affected line item in the consolidated statement of operations
		from accumulated other
		comprehensive income
	Unrealized gains (losses) on available for sale securities	$	-2,594		Other net realized investment gains
			-		Income tax expense
		$	-2,594		Total net of income taxes
	Gains (losses) on cash flow hedges interest rate swaps	$	1,084		Interest expense
			-		Income tax expense
		$	1,084		Total net of income taxes

Debt_Tables

Debt (Tables)	6 Months Ended
	Jun. 30, 2013
Borrowings	'
	The Company’s borrowings consisted of the following at June 30, 2013 and December 31, 2012:
				June 30, 2013							December 31, 2012
	($ in thousands)			Carrying				Fair			Carrying		Fair
				Value				Value			Value		Value
	Credit facility	$			70,000			$	70,000	$		70,000	$	70,000
	Convertible senior notes				146,166				158,243			144,673		152,063
	Subordinated debentures				235,058				240,010			235,058		232,678
	Total	$			451,224			$	468,253	$		449,731	$	454,741
Amounts Recorded for Notes	'
	The following table shows the amounts recorded for the Notes as of June 30, 2013 and December 31, 2012:
		June 30,				December 31,
	($ in thousands)	2013				2012
	Liability component
	Outstanding principal	$	150,000			$	150,000
	Unamortized OID		(3,834	)			(5,327	)
	Liability component		146,166				144,673
	Equity component, net of tax	$	7,469			$	7,469

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2013
Analysis of Restricted Stock Activity	'
	The following table provides an analysis of restricted stock activity for the six months ended June 30, 2013 and 2012 (historical share counts and fair values have been adjusted for the 1.1330 share conversion ratio, as discussed more fully in “Note 4 – Merger Transaction”):
		Six Months Ended June 30,
		2013					2012
		Number			Weighted		Number			Weighted
		of Shares			Average		of Shares			Average
					Grant Date					Grant Date
					Fair Value					Fair Value
	Outstanding, January 1		1,015,902		$	20.19		1,120,091		$	20.69
	Granted		242,626			18.09		363,894			20.37
	Vested		(953,242	)		20.43		(439,734	)		21.07
	Forfeitures		(14,015	)		19.26		(9,874	)		20.83
	Outstanding, June 30,		291,271		$	17.68		1,034,377		$	20.38
Analysis of Stock Option Activity	'
	The following table provides an analysis of stock option activity for the six months ended June 30, 2013 and 2012 (historical share counts and fair values have been adjusted for the 1.1330 share conversion ratio, as discussed more fully in “Note 4 – Merger Transaction”):
		Six Months Ended June 30,
		2013					2012
		Number of			Average		Number of			Average
		Shares			Exercise		Shares			Exercise
					Price					Price
	Outstanding, January 1		969,307		$	17.78		969,315		$	17.78
	Exercised		(2,674	)		16.48		-			-
	Forfeitures and expirations		(7,657	)		17.72		-			-
	Outstanding, June 30		958,976		$	17.78		969,315		$	17.78
	Exercisable, June 30		958,976		$	17.78		969,315		$	17.78
Analysis of Stock Based Compensation Expense	'
	The following table provides an analysis of stock based compensation expense for the six months ended June 30, 2013 and 2012:
		Six Months
		Ended June 30,
	($ in thousands)	2013			2012
	Restricted stock
	Expense, net of tax	$	8,204		$	896
	Value of shares vested		21,042			8,576
	Value of unvested shares		5,974			19,257
	Stock options
	Intrinsic value of outstanding options		3,471			1,632
	Intrinsic value of vested outstanding options		3,471			1,632
	Unrecognized compensation expense
	Unvested restricted stock, net of tax		5,974			12,791
	Weighted average years over which expense will be recognized		3.6			2.5

Earnings_Loss_per_Share_Tables

Earnings (Loss) per Share (Tables)	6 Months Ended
	Jun. 30, 2013
Computation of Earnings Per Share	'
	The following table shows the computation of the earnings per share (historical earnings per share amounts have been adjusted for the 1.1330 share conversion ratio in connection with the Merger Transaction):
		Three Months						Six Months
		Ended June 30,						Ended June 30,
	($ in thousands, except per share amounts)	2013			2012			2013			2012
	Numerator
	Net income (loss) attributable to Tower Group International, Ltd.	$	(507,342	)	$	(16,809	)	$	(494,425	)	$	2,356
	Less: Allocation of income for unvested participating restricted stock		-			-			-			-
	Less: Dividends on unvested participating restricted stock		(48	)		(173	)		(215	)		(347	)
	Net income available to common shareholders - Basic		(507,390	)		(16,982	)		(494,640	)		2,009
	Reallocation of income for unvested participating restricted stock		-			-			-			-
	Net income available to common shareholders - Diluted		(507,390	)		(16,982	)		(494,640	)		2,009
	Denominator
	Basic earning per share denominator		57,135			43,289			51,487			43,340
	Effect of dilutive securities		-			-			-			70
	Diluted earnings per share denominator		57,135			43,289			51,487			43,410
	Earnings (loss) per share attributable to Tower Group International, Ltd. - Basic
	Common stock:
	Distributed earnings	$	0.17		$	0.17		$	0.34		$	0.34
	Undistributed earnings	$	(9.05	)	$	(0.56	)	$	(9.95	)	$	(0.29	)
	Total	$	(8.88	)	$	(0.39	)	$	(9.61	)	$	0.05
	Earnings (loss) per share attributable to Tower Group International, Ltd. - Diluted	$	(8.88	)	$	(0.39	)	$	(9.61	)	$	0.05

Segment_Information_Tables

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2013
Business Segments Results	'
	Business segment results are as follows:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Commercial Insurance Segment
	Revenues
	Premiums earned	$	170,832		$	193,793		$	348,827		$	381,651
	Ceding commission revenue		(8,301	)		(732	)		(8,237	)		(2,778	)
	Policy billing fees		1,422			1,390			2,792			2,903
	Total revenues		163,953			194,451			343,382			381,776
	Expenses
	Loss and loss adjustment expenses		249,906			155,395			373,293			272,239
	Underwriting expenses		66,614			63,832			129,383			128,245
	Total expenses		316,520			219,227			502,676			400,484
	Underwriting profit (loss)	$	(152,567	)	$	(24,776	)	$	(159,294	)	$	(18,708	)
	Specialty Insurance and Reinsurance Segment
	Revenues
	Premiums earned	$	122,211		$	143,857		$	251,999		$	253,834
	Ceding commission revenue		3,528			4,626			6,751			6,682
	Total revenues		125,739			148,483			258,750			260,516
	Expenses
	Loss and loss adjustment expenses		248,466			125,814			321,442			210,408
	Underwriting expenses		56,772			50,122			106,915			88,851
	Total expenses		305,238			175,936			428,357			299,259
	Underwriting profit (loss)	$	(179,499	)	$	(27,453	)	$	(169,607	)	$	(38,743	)
	Personal Insurance Segment
	Revenues
	Premiums earned	$	125,321		$	122,503		$	239,424		$	244,826
	Ceding commission revenue		12,044			6,186			22,908			11,339
	Policy billing fees		1,899			1,610			3,679			3,231
	Total revenues		139,264			130,299			266,011			259,396
	Expenses
	Loss and loss adjustment expenses		61,520			68,566			140,889			134,621
	Underwriting expenses		63,709			56,164			121,696			107,617
	Total expenses		125,229			124,730			262,585			242,238
	Underwriting profit (loss)	$	14,035		$	5,569		$	3,426		$	17,158
	Tower	$	14,139		$	9,376		$	16,156		$	21,213
	Reciprocal Exchanges		(104	)		(3,807	)		(12,730	)		(4,055	)
	Total underwriting profit (loss)	$	14,035		$	5,569		$	3,426		$	17,158
Reconciliation of Revenue by Segment to Consolidated Revenues	'
	The following table reconciles revenue by segment to consolidated revenues:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Commercial Insurance segment	$	163,953		$	194,451		$	343,382		$	381,776
	Specialty Insurance and Reinsurance segment		125,739			148,483			258,750			260,516
	Personal Insurance segment		139,264			130,299			266,011			259,396
	Total segment revenues		428,956			473,233			868,143			901,688
	Net investment income		28,402			31,781			58,719			65,724
	Net realized gains (losses) on investments, including other-than-temporary impairments		(2,034	)		19			4,817			3,347
	Corporate and other		5,194			1,359			5,322			1,856
	Consolidated revenues	$	460,518		$	506,392		$	937,001		$	972,615
Reconciliation of Results of Individual Segments to Consolidated Income Before Income Taxes	'
	The following table reconciles the results of the Company’s individual segments to consolidated income before income taxes:
		Three Months Ended						Six Months Ended
		June 30,						June 30,
	($ in thousands)	2013			2012			2013			2012
	Commercial Insurance segment underwriting profit (loss)	$	(152,567	)	$	(24,776	)	$	(159,294	)	$	(18,708	)
	Specialty Insurance and Reinsurance segment underwriting profit (loss)		(179,499	)		(27,453	)		(169,607	)		(38,743	)
	Personal Insurance segment underwriting profit (loss)		14,035			5,569			3,426			17,158
	Net investment income		28,402			31,781			58,719			65,724
	Net realized gains on investments, including other-than-temporary impairments		(2,034	)		19			4,817			3,347
	Corporate and other		(2,297	)		(1,809	)		(5,239	)		(4,173	)
	Acquisition-related transaction costs		(665	)		(720	)		(19,721	)		(1,982	)
	Interest expense		(7,635	)		(7,902	)		(15,443	)		(16,513	)
	Goodwill impairment		(214,049	)		-			(214,049	)		-
	Equity income in unconsolidated affiliate		7,838			-			7,966			-
	Income before income taxes	$	(508,471	)	$	(25,291	)	$	(508,425	)	$	6,110

Nature_of_Business_Additional_

Nature of Business - Additional Information (Detail) (USD $)

3 Months Ended

6 Months Ended

6 Months Ended

6 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2012

Dec. 31, 2012

Jun. 30, 2013

Jun. 30, 2013

Dec. 31, 2012

Jun. 30, 2013

Oct. 01, 2013

Oct. 01, 2013

Oct. 01, 2013

Oct. 01, 2013

Jun. 30, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Segment

Maximum

Convertible Senior Notes

Convertible Senior Notes

Tower Reinsurance, Ltd.

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

New Reinsurance Program

Scenario, Forecast

Scenario, Forecast

Scenario, Forecast

Scenario, Forecast

Commercial Insurance

Commercial Insurance

Specialty Insurance and Reinsurance

Specialty Insurance and Reinsurance

Tower Insurance Company of New York

Tower Insurance Company of New York

Tower Insurance Company of New York

Tower Reinsurance, Ltd.

Tower Reinsurance, Ltd.

Minimum

Tower Reinsurance, Ltd.

Tower Reinsurance, Ltd.

CastlePoint Reinsurance Company, Ltd.

Southport Re

Hannover

Arch

Agreement

Minimum

Minimum

Minimum

Nature Of Business [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reserve charge from adverse development associated with prior accident years

$326,700,000

$326,916,000

$72,001,000

'

'

'

'

$175,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of loss reserves covered by reserve study

'

90.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Goodwill impairment charge

214,049,000

214,049,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

214,049,000

'

'

Quota share reinsurance cede, percentage

'

'

'

'

'

'

'

'

30.00%

14.00%

17.50%

'

'

'

'

'

'

'

'

'

'

Net written premiums

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

169,100,000

343,600,000

103,700,000

306,600,000

Additional collateral requested

'

'

'

'

'

'

'

'

'

'

'

26,300,000

'

'

'

'

'

'

'

'

'

Adverse loss reserve development from loss portfolio transaction

'

'

'

'

'

'

'

175,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Reinsurance capital reserve

890,186,000

890,186,000

'

137,545,000

'

'

'

8,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount required to be collateralized against adverse loss reserve development

657,275,000

657,275,000

'

98,581,000

'

'

'

175,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Unencumbered liquid assets

27,333,000

27,333,000

'

17,609,000

'

'

'

96,000,000

'

'

'

'

79,000,000

'

'

'

'

'

'

'

'

Number of reinsurance treaties commuted

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

Credit facility outstanding

70,000,000

70,000,000

'

70,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding principal

'

'

'

'

'

150,000,000

150,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, Consolidated Net Worth

'

553,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, percentage of Consolidated Net Worth

90.00%

90.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, covenant increase as a percentage of any new capital

'

90.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, additional covenant increase as a percentage of net income above base

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, net income amount base for additional covenant increase

'

20,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, Debt to capitalization ratio limit

'

46.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, risk based capital ratio

'

'

'

'

'

'

'

'

'

'

'

'

'

175.00%

'

'

'

'

'

'

'

Credit facility covenant, consolidated statutory surplus

'

'

'

'

'

'

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

'

'

Credit facility covenant, percentage of required capital

'

'

'

'

'

'

'

'

'

'

'

'

'

'

110.00%

110.00%

150.00%

'

'

'

'

Credit facility covenant, minimum statutory surplus

419,000,000

419,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, combined surplus

'

85.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Subordinated debentures outstanding

235,058,000

235,058,000

'

235,058,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Subordinated debentures

$10,000,000

$10,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Subordinated debentures maturity date

'May 2033

'May 2033

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum number of quarters to defer interest payments

'

'

'

'

'60 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of business segments

'

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restatement_of_Previously_Issu2

Restatement of Previously Issued Financial Statements - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
						Revised Amount	Revised Amount	Revised Amount	Revised Amount	Revised Amount	Revised Amount
								Material Error in Liability for Unpaid Claims and Claims Adjustment Expense	Material Error in Liability for Unpaid Claims and Claims Adjustment Expense	Material Error in Liability for Unpaid Claims and Claims Adjustment Expense	Material Error in Liability for Unpaid Claims and Claims Adjustment Expense
Reserve charge from adverse development associated with prior accident years	$326,700	'	$326,916	$72,001	'	$365,000	'	'	'	'	'
Loss and loss adjustment expenses	559,892	349,775	835,624	617,268	'	'	'	9,600	21,700	5,700	'
Reinsurance recoverables on unpaid losses	690,069	'	690,069	'	459,457	'	-36,735	-37,000	-27,400	-5,700	'
Premium receivable	392,433	'	392,433	'	412,045	'	-10,067	-11,000	-10,000	-5,600	-7,200
Other operating expenses	$88,308	$78,100	$172,701	$155,171	'	'	'	$1,000	$4,400	($1,600)	$7,200

Effect_of_Restatement_and_Rela

Effect of Restatement and Related Tax Effects on Previously Filled Consolidated Balance Sheet (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Assets	'	'	'	'
Total investments	$2,517,362	$2,553,505	'	'
Cash and cash equivalents	108,535	102,269	199,005	114,098
Investment income receivable	26,182	25,332	'	'
Investment in unconsolidated affiliate	'	71,894	'	'
Premiums receivable	392,433	412,045	'	'
Reinsurance recoverable on paid losses	27,333	17,609	'	'
Reinsurance recoverable on unpaid losses	690,069	459,457	'	'
Prepaid reinsurance premiums	126,159	63,923	'	'
Deferred acquisition costs, net	192,887	181,198	'	'
Intangible assets	99,507	106,768	'	'
Goodwill	55,540	241,458	'	'
Funds held by reinsured companies	890,186	137,545	'	'
Other assets	465,548	338,769	'	'
Total assets	5,667,937	4,711,772	'	'
Liabilities	'	'	'	'
Loss and loss adjustment expenses	2,552,351	1,895,679	1,701,833	1,632,113
Unearned premium	998,624	921,271	'	'
Reinsurance balances payable	46,442	40,569	'	'
Funds held under reinsurance agreements	657,275	98,581	'	'
Other liabilities	350,838	296,960	'	'
Deferred income taxes	'	24,763	'	'
Debt	451,224	449,731	'	'
Total liabilities	5,077,036	3,727,554	'	'
Contingencies	'	'	'	'
Stockholders' equity	'	'	'	'
Common stock	574	530	'	'
Treasury stock	-17	-181,435	'	'
Paid-in-capital	812,547	780,036	'	'
Accumulated other comprehensive income	9,060	82,756	'	'
Retained earnings	-242,930	268,171	'	'
Tower Group, Inc. stockholders' equity	579,234	950,058	'	'
Noncontrolling interests	11,667	34,160	'	'
Total stockholders' equity	590,901	984,218	1,029,052	1,037,131
Total liabilities and stockholders' equity	5,667,937	4,711,772	'	'
As previously Reported	'	'	'	'
Assets	'	'	'	'
Total investments	'	2,554,505	'	'
Cash and cash equivalents	'	100,293	'	'
Investment income receivable	'	25,332	'	'
Investment in unconsolidated affiliate	'	70,830	'	'
Premiums receivable	'	422,112	'	'
Reinsurance recoverable on paid losses	'	17,609	'	'
Reinsurance recoverable on unpaid losses	'	496,192	'	'
Prepaid reinsurance premiums	'	63,923	'	'
Deferred acquisition costs, net	'	180,941	'	'
Intangible assets	'	106,768	'	'
Goodwill	'	241,458	'	'
Funds held by reinsured companies	'	137,545	'	'
Other assets	'	331,506	'	'
Total assets	'	4,749,014	'	'
Liabilities	'	'	'	'
Loss and loss adjustment expenses	'	1,895,073	'	'
Unearned premium	'	920,859	'	'
Reinsurance balances payable	'	40,569	'	'
Funds held under reinsurance agreements	'	98,581	'	'
Other liabilities	'	292,239	'	'
Deferred income taxes	'	36,464	'	'
Debt	'	449,731	'	'
Total liabilities	'	3,733,516	'	'
Contingencies	'	'	'	'
Stockholders' equity	'	'	'	'
Common stock	'	530	'	'
Treasury stock	'	-181,435	'	'
Paid-in-capital	'	780,036	'	'
Accumulated other comprehensive income	'	83,406	'	'
Retained earnings	'	298,299	'	'
Tower Group, Inc. stockholders' equity	'	980,836	'	'
Noncontrolling interests	'	34,662	'	'
Total stockholders' equity	'	1,015,498	'	'
Total liabilities and stockholders' equity	'	4,749,014	'	'
Revised Amount	'	'	'	'
Assets	'	'	'	'
Total investments	'	-1,000	'	'
Cash and cash equivalents	'	1,976	'	'
Investment in unconsolidated affiliate	'	1,064	'	'
Premiums receivable	'	-10,067	'	'
Reinsurance recoverable on unpaid losses	'	-36,735	'	'
Deferred acquisition costs, net	'	257	'	'
Other assets	'	7,263	'	'
Total assets	'	-37,242	'	'
Liabilities	'	'	'	'
Loss and loss adjustment expenses	'	606	'	'
Unearned premium	'	412	'	'
Other liabilities	'	4,721	'	'
Deferred income taxes	'	-11,701	'	'
Total liabilities	'	-5,962	'	'
Contingencies	'	'	'	'
Stockholders' equity	'	'	'	'
Accumulated other comprehensive income	'	-650	'	'
Retained earnings	'	-30,128	'	'
Tower Group, Inc. stockholders' equity	'	-30,778	'	'
Noncontrolling interests	'	-502	'	'
Total stockholders' equity	'	-31,280	'	'
Total liabilities and stockholders' equity	'	($37,242)	'	'

Accounting_Policies_and_Basis_3

Accounting Policies and Basis of Presentation - Additional Information (Detail) (USD $)	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2012	Mar. 31, 2012
In Thousands, unless otherwise specified			Reciprocal Exchanges	Tower
Significant Accounting Policies [Line Items]	'	'	'	'
Transfer of assets	'	'	$1,800	$1,800
Conversion ratio	1.133	1.133	'	'

Reflects_the_Previously_Report

Reflects the Previously Reported and Revised Shareholders' Equity Accounts (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Common stock	$574	'	$574	'	$530
Treasury stock	-17	'	-17	'	-181,435
Paid-in-capital	812,547	'	812,547	'	780,036
Earnings (Loss) per Share:	'	'	'	'	'
Basic	($8.88)	($0.39)	($9.61)	$0.05	'
Diluted	($8.88)	($0.39)	($9.61)	$0.05	'
Weighted average common shares outstanding	'	'	'	'	'
Basic	57,135	43,289	51,487	43,340	'
Diluted	57,135	43,289	51,487	43,410	'
As Previously Reported	'	'	'	'	'
Common stock	'	'	'	'	469
Treasury stock	'	'	'	'	-181,435
Paid-in-capital	'	'	'	'	780,097
Earnings (Loss) per Share:	'	'	'	'	'
Basic	'	($0.43)	'	$0.06	'
Diluted	'	($0.43)	'	$0.06	'
Weighted average common shares outstanding	'	'	'	'	'
Basic	'	39,117	'	39,206	'
Diluted	'	39,117	'	39,268	'
Revised	'	'	'	'	'
Common stock	'	'	'	'	530
Treasury stock	'	'	'	'	-181,435
Paid-in-capital	'	'	'	'	$780,036
Earnings (Loss) per Share:	'	'	'	'	'
Basic	'	($0.39)	'	$0.05	'
Diluted	'	($0.39)	'	$0.05	'
Weighted average common shares outstanding	'	'	'	'	'
Basic	'	43,289	'	43,340	'
Diluted	'	43,289	'	43,410	'

Merger_Transaction_Additional_

Merger Transaction - Additional Information (Detail) (USD $)

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

1 Months Ended

1 Months Ended

Jun. 30, 2013

Jun. 30, 2012

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2012

Dec. 31, 2012

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Jul. 30, 2012

Jun. 30, 2013

Mar. 06, 2013

Aug. 20, 2012

Mar. 06, 2013

Direct cost

Direct cost

Compensation expense

Compensation expense

Professional Fees And Other

Tower Group International Ltd

Third Party Investors

Canopius Group Limited

Canopius Group Limited

Canopius Group Limited

Canopius Group Limited

Canopius Group Limited

Restricted Stock

Third Party Investors

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Investments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$26,485,000

'

$74,900,000

'

Percentage of ownership interest

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

10.70%

'

Payment to exercise merger option

'

'

'

'

'

'

'

'

'

'

'

'

'

1,000,000

'

'

'

'

Percentage of private sale of shares to third party investor

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

Net consideration of sale of shares to third party

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

205,862,755

Shares issued in private placement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

14,025,737

'

'

Merger agreement terms

'

'

'

'(i) 100% of the issued and outstanding shares of TGI common stock was cancelled and automatically converted into the right to receive 1.1330 common shares of the Company, par value $0.01 per share (the "Common Share"), (ii) each outstanding option to acquire TGI common stock, whether vested or unvested and whether granted under TGIbs 2008 Long-Term Equity Compensation Plan or otherwise, automatically vested, free of any forfeiture conditions, and constituted a fully vested option to acquire that number of Common Shares (rounded down to the nearest whole number) equal to the number of shares of TGI common stock subject to such option multiplied by 1.1330, on the same terms and conditions (other than vesting and performance conditions) as were applicable to such TGI stock option immediately prior to the Merger Transaction, with the exercise price of such option adjusted to be the original exercise price divided by 1.1330, and (iii) substantially all issued and outstanding shares of TGI restricted stock, whether granted under TGI's 2008 Long-Term Equity Compensation Plan or otherwise, automatically vested, free of any forfeiture conditions, and was converted into the right to receive, as soon as reasonably practicable after the effective time, 1.1330 Common Shares.

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Conversion ratio

1.133

1.133

1.133

1.133

1.133

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of outstanding shares

57,429,099

'

57,429,099

57,429,099

'

43,513,678

'

'

'

'

'

'

'

'

57,432,150

'

'

'

Percentage of outstanding shares held

'

'

'

'

'

'

'

'

'

'

'

76.00%

24.00%

'

'

'

'

'

Direct cost of the acquisition

665,000

720,000

'

19,721,000

1,982,000

'

700,000

19,700,000

11,600,000

10,300,000

8,100,000

'

'

'

'

'

'

'

Unamortized reserve for risk premium

19,100,000

'

19,100,000

19,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Consolidated revenue since effective date of merger

'

'

40,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Consolidated net income (loss) since effective date of merger

'

'

($22,000,000)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preliminary_Purchase_Considera

Preliminary Purchase Consideration (Detail) (Canopius Group Limited, USD $)	Jun. 30, 2013
In Thousands, unless otherwise specified
Business Acquisition [Line Items]	'
Preliminary purchase consideration	$207,347
Consideration received by Canopius Group from the third party sale	'
Business Acquisition [Line Items]	'
Preliminary purchase consideration	205,863
Fair value of Merger Option received in connection with TGI's investment in Canopius Group	'
Business Acquisition [Line Items]	'
Preliminary purchase consideration	484
Exercise price of Merger Right received from TGI upon exercise	'
Business Acquisition [Line Items]	'
Preliminary purchase consideration	$1,000

Fair_Values_of_Respective_Asse

Fair Values of Respective Assets Acquired and Liabilities Assumed (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013	Aug. 20, 2012	Jun. 30, 2013
In Thousands, unless otherwise specified			Canopius Group Limited	Canopius Group Limited	Canopius Group Limited
					Unpaid Losses and Loss Adjustment Expenses
Assets	'	'	'	'	'
Cash and cash equivalents	'	'	$134,741	'	'
Investments	'	'	26,485	74,900	'
Reinsurance recoverables	'	'	468,727	'	'
Prepaid reinsurance	'	'	152,431	'	'
Funds held by reinsured companies	'	'	698,819	'	'
Other assets	'	'	75,219	'	'
Liabilities	'	'	'	'	'
Unearned premiums	'	'	169,963	'	'
Funds held under reinsurance agreements	'	'	560,714	'	'
Other liabilities	'	'	15,916	'	630,613
Net assets acquired	'	'	179,216	'	'
Purchase Consideration	'	'	207,347	'	'
Goodwill	$55,540	$241,458	$28,131	'	'

Pro_Forma_Financial_Informatio

Pro Forma Financial Information (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Business Acquisition, Pro Forma Information [Line Items]	'	'	'	'
Revenues	$460,518	$509,666	$940,145	$979,033
Net Income (Loss)	($505,876)	($16,887)	($485,248)	$10,074

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	6 Months Ended
In Thousands, unless otherwise specified	Mar. 13, 2013	Jun. 30, 2013	Jun. 30, 2013
			Segment
Intangible Assets And Goodwill [Line Items]	'	'	'
Goodwill from Merger Transaction	$28,100	'	$28,131
Number of business segments	'	'	3
Goodwill impairment charge	'	214,049	214,049
Customer relationships	'	'	'
Intangible Assets And Goodwill [Line Items]	'	'	'
Impairment of intangible assets	'	'	$3,800

Summary_of_Goodwill_by_Reporti

Summary of Goodwill by Reporting Units (Detail) (USD $)	1 Months Ended	3 Months Ended	6 Months Ended
In Thousands, unless otherwise specified	Mar. 13, 2013	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
				Commercial Insurance	Personal Insurance	Personal Insurance
Goodwill [Line Items]	'	'	'	'	'	'
Opening balance	'	'	$241,458	$185,918	$55,540	$55,540
Goodwill from Merger Transaction	28,100	'	28,131	28,131	'	'
Goodwill impairment	'	-214,049	-214,049	-214,049	'	'
Closing balance	'	$55,540	$55,540	'	$55,540	$55,540

Variable_Interest_Entities_VIE1

Variable Interest Entities ("VIEs") - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Variable Interest Entity [Line Items]	'	'	'	'
Total revenues	$460,518	$506,392	$937,001	$972,615
Total expenses	762,778	531,683	1,239,343	966,505
Net income (loss)	801	437	-10,480	3,448
Reciprocal Exchanges	'	'	'	'
Variable Interest Entity [Line Items]	'	'	'	'
Total revenues	49,100	49,200	96,400	99,400
Total expenses	48,300	48,800	106,900	96,000
Net income (loss)	$800	$400	($10,500)	$3,400

Summary_of_Cost_or_Amortized_C

Summary of Cost or Amortized Cost and Fair Value of Investments in Fixed Maturity and Equity Securities, Gross Unrealized Gains and Losses, and Other-Than-Temporary Impairment Losses (Detail) (USD $)	Jun. 30, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	$2,373,171		$2,344,283
Gross Unrealized Gains	97,330		159,147
Gross Unrealized Losses	-30,177		-7,711
Investments	2,440,324		2,495,719
Unrealized OTTI Losses	-884	[1]	-6	[1]
Tower	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	2,121,665		2,075,189
Gross Unrealized Gains	87,920		141,614
Gross Unrealized Losses	-25,786		-7,210
Investments	2,183,799		2,209,593
Unrealized OTTI Losses	-884	[1]	-6	[1]
Reciprocal Exchanges	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	251,506		269,094
Gross Unrealized Gains	9,410		17,533
Gross Unrealized Losses	-4,391		-501
Investments	256,525		286,126
Fixed-maturity securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	2,229,407		2,190,186
Gross Unrealized Gains	88,679		157,463
Gross Unrealized Losses	-28,541		-2,938
Investments	2,289,545		2,344,711
Unrealized OTTI Losses	-884	[1]	-6	[1]
Fixed-maturity securities | U.S. Treasury Securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	390,003		183,462
Gross Unrealized Gains	1,024		1,500
Gross Unrealized Losses	-5,780		-13
Investments	385,247		184,949
Fixed-maturity securities | U.S. Agency securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	104,099		98,502
Gross Unrealized Gains	2,189		4,351
Gross Unrealized Losses	-965		-76
Investments	105,323		102,777
Fixed-maturity securities | Municipal Bonds	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	568,991		633,373
Gross Unrealized Gains	24,132		52,914
Gross Unrealized Losses	-5,732		-244
Investments	587,391		686,043
Unrealized OTTI Losses	-71	[1]	'
Fixed-maturity securities | Corporate Securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Investments	729,899		746,665
Fixed-maturity securities | Corporate Securities | Finance	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	246,779		233,849
Gross Unrealized Gains	14,594		21,293
Gross Unrealized Losses	-4,240		-1,095
Investments	257,133		254,047
Fixed-maturity securities | Corporate Securities | Industrial	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	406,976		412,465
Gross Unrealized Gains	13,171		26,556
Gross Unrealized Losses	-5,675		-868
Investments	414,472		438,153
Fixed-maturity securities | Corporate Securities | Utilities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	58,368		51,698
Gross Unrealized Gains	2,078		2,958
Gross Unrealized Losses	-2,152		-191
Investments	58,294		54,465
Unrealized OTTI Losses	-203	[1]	'
Fixed-maturity securities | Commercial mortgage-backed securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	217,531		211,819
Gross Unrealized Gains	21,439		30,375
Gross Unrealized Losses	-2,351		-141
Investments	236,619		242,053
Unrealized OTTI Losses	-604	[1]	'
Fixed-maturity securities | Residential mortgage-backed securities, Agency backed securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	161,783		283,652
Gross Unrealized Gains	4,891		12,326
Gross Unrealized Losses	-1,614		-262
Investments	165,060		295,716
Fixed-maturity securities | Residential mortgage-backed securities, Non-agency backed securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	35,583		38,615
Gross Unrealized Gains	4,059		3,575
Gross Unrealized Losses	-30		-34
Investments	39,612		42,156
Unrealized OTTI Losses	-6	[1]	-6	[1]
Fixed-maturity securities | Asset-Backed Securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	39,294		42,751
Gross Unrealized Gains	1,102		1,615
Gross Unrealized Losses	-2		-14
Investments	40,394		44,352
Preferred stocks	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	21,584		31,272
Gross Unrealized Gains	188		730
Gross Unrealized Losses	-1,137		-481
Investments	20,635		31,521
Common Stocks	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	108,765		118,076
Gross Unrealized Gains	8,463		953
Gross Unrealized Losses	-463		-4,292
Investments	116,765		114,737
Short-term investments	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	13,415		4,749
Gross Unrealized Gains	'		1
Gross Unrealized Losses	-36		'
Investments	$13,379		$4,750
[1]	Represents the gross unrealized loss on other-than-temporarily impaired securities recognized in accumulated other comprehensive income (loss).

Investments_Additional_Informa

Investments - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
	Investment
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Restricted assets, cash and cash equivalents	$32,000,000	'	'
Investment, carrying values	2,373,171,000	'	2,344,283,000
Proceeds from sale of equity securities	802,297,000	745,618,000	'
Number of securities in unrealized loss position not deemed OTTI	668	'	'
Unrealized losses	30,177,000	'	7,711,000
Unrealized losses related to securities in loss position for more than 12 months	415,000	'	577,000
Future funding commitments to limited partnerships	47,000,000	'	'
Fixed-maturity securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Number of securities in unrealized loss position not deemed OTTI	644	'	'
Unrealized losses	28,500,000	'	'
Percentage of fixed maturity securities in unrealized loss position below amortized cost	3.00%	'	'
Number of securities in unrealized loss position for more than 12 months	27	'	'
Unrealized losses related to securities in loss position for more than 12 months	100,000	'	'
Common Stocks	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Number of securities in unrealized loss position not deemed OTTI	17	'	'
Unrealized losses	500,000	'	'
Fixed-maturity securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Proceeds from sale or maturity of fixed maturity securities	759,000,000	980,000,000	'
Equity securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Proceeds from sale of equity securities	796,800,000	745,600,000	'
US Treasury Notes and Other Securities | Held by Counterparties	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Restricted assets, cash and cash equivalents	457,300,000	'	'
Investment, carrying values	'	'	481,500,000
Corporate bonds and mortgage-backed securities | Fixed-maturity securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Unrealized losses	16,100,000	'	'
Tower	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Investment, carrying values	2,121,665,000	'	2,075,189,000
Unrealized losses	25,786,000	'	7,210,000
Unrealized losses related to securities in loss position for more than 12 months	$400,000	'	$478,000
Tower | Other	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Number of securities purchased	5	'	'

Summary_of_Major_Categories_of

Summary of Major Categories of Net Investment Income (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	$29,834	$33,135	$61,926	$68,456
Investment expenses	-1,432	-1,354	-3,207	-2,732
Net investment income	28,402	31,781	58,719	65,724
Tower	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Net investment income	27,612	30,267	57,195	62,525
Reciprocal Exchanges	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Net investment income	2,458	3,177	4,839	6,526
Consolidation, Eliminations	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Net investment income	-1,668	-1,663	-3,315	-3,327
Fixed-maturity securities	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	20,562	24,511	41,535	49,924
Equity securities	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	6,808	6,603	13,292	14,239
Cash and cash equivalents	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	19	505	70	798
Other invested asset	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	2,158	1,313	6,414	3,146
Other	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	$287	$203	$615	$349

Summary_of_Gross_Realized_Gain

Summary of Gross Realized Gains, Losses and Impairment Write-Downs on Investments (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Gain (Loss) on Investments [Line Items]	'	'	'	'
Net realized gains (losses) on investments	$2,422	$2,003	$9,962	$8,307
Other-than-temporary impairment losses	-4,456	-1,984	-5,145	-4,960
Total net realized investment gains (losses)	-2,034	19	4,817	3,347
Tower	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Other-than-temporary impairment losses	-4,456	-1,984	-5,145	-4,960
Total net realized investment gains (losses)	-2,243	-110	3,990	1,028
Reciprocal Exchanges	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Total net realized investment gains (losses)	209	129	827	2,319
Fixed-maturity securities	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Gross realized gains	10,479	12,354	17,843	25,162
Gross realized losses	-1,672	-609	-1,862	-2,551
Net realized gains (losses) on investments	8,807	11,745	15,981	22,611
Other-than-temporary impairment losses	-23	-765	-187	-882
Equity securities	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Gross realized gains	5,323	2,685	9,559	4,179
Gross realized losses	-12,717	-9,808	-17,530	-16,160
Net realized gains (losses) on investments	-7,394	-7,123	-7,971	-11,981
Other-than-temporary impairment losses	-4,433	-1,219	-4,958	-4,078
Other	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Gross realized gains	2,100	555	3,855	1,790
Gross realized losses	-1,091	-3,174	-1,903	-4,113
Net realized gains (losses) on investments	$1,009	($2,619)	$1,952	($2,323)

Amount_of_FixedMaturity_and_Eq

Amount of Fixed-Maturity and Equity Securities that were Other-Than-Temporary Impairment (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	($4,456)	($2,270)	($5,145)	($5,246)
Portion of loss recognized in accumulated other comprehensive income (loss)	'	286	'	286
Other-than-temporary impairment losses	-4,456	-1,984	-5,145	-4,960
Tower	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairment losses	-4,456	-1,984	-5,145	-4,960
Corporate Securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	'	-648	'	-737
Commercial mortgage-backed securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	-23	-403	-47	-403
Residential mortgage-backed securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	-140	'	-140	-28
Equity securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	($4,293)	($1,219)	($4,958)	($4,078)

Rollforward_of_Cumulative_Amou

Rollforward of Cumulative Amount of Other-Than-Temporary Impairment for Securities Still Held Showing Amounts that have been Included in Earnings on Pretax Basis (Detail) (Tower, USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Tower	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Balance at beginning of period	$4,516	$6,084	$4,492	$12,666
Additional credit losses recognized during the period, related to securities for which no OTTI has been previously recognized	23	765	47	854
Additional credit losses recognized during the period, related to securities for which OTTI has been previously recognized	'	'	'	28
Reductions due to Securities sold during the period (realized)	'	-730	'	-7,429
Balance at end of period	$4,539	$6,119	$4,539	$6,119

Information_Regarding_Invested

Information Regarding Invested Assets that were in Unrealized Loss Position (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	$983,435	$328,618
Less than 12 Months, Unrealized Losses	-29,762	-7,134
12 Months or Longer, Fair Value	7,919	15,110
12 Months or Longer, Unrealized Losses	-415	-577
Total, Aggregate Fair Value	991,354	343,728
Total, Unrealized Losses	-30,177	-7,711
Tower	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	875,960	270,609
Less than 12 Months, Unrealized Losses	-25,386	-6,732
12 Months or Longer, Fair Value	7,553	13,338
12 Months or Longer, Unrealized Losses	-400	-478
Total, Aggregate Fair Value	883,513	283,947
Total, Unrealized Losses	-25,786	-7,210
Reciprocal Exchanges	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	107,475	58,009
Less than 12 Months, Unrealized Losses	-4,376	-402
12 Months or Longer, Fair Value	366	1,772
12 Months or Longer, Unrealized Losses	-15	-99
Total, Aggregate Fair Value	107,841	59,781
Total, Unrealized Losses	-4,391	-501
Fixed-maturity securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	917,916	263,342
Less than 12 Months, Unrealized Losses	-28,442	-2,687
12 Months or Longer, Fair Value	1,830	9,386
12 Months or Longer, Unrealized Losses	-99	-251
Total, Aggregate Fair Value	919,746	272,728
Total, Unrealized Losses	-28,541	-2,938
Fixed-maturity securities | U.S. Treasury Securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	318,415	44,347
Less than 12 Months, Unrealized Losses	-5,780	-13
Total, Aggregate Fair Value	318,415	44,347
Total, Unrealized Losses	-5,780	-13
Fixed-maturity securities | U.S. Agency securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	32,802	22,345
Less than 12 Months, Unrealized Losses	-965	-76
Total, Aggregate Fair Value	32,802	22,345
Total, Unrealized Losses	-965	-76
Fixed-maturity securities | Municipal Bonds	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	151,394	21,532
Less than 12 Months, Unrealized Losses	-5,688	-235
12 Months or Longer, Fair Value	218	251
12 Months or Longer, Unrealized Losses	-44	-9
Total, Aggregate Fair Value	151,612	21,783
Total, Unrealized Losses	-5,732	-244
Fixed-maturity securities | Corporate Securities | Finance	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	76,192	16,853
Less than 12 Months, Unrealized Losses	-4,240	-1,095
Total, Aggregate Fair Value	76,192	16,853
Total, Unrealized Losses	-4,240	-1,095
Fixed-maturity securities | Corporate Securities | Industrial	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	188,193	53,576
Less than 12 Months, Unrealized Losses	-5,635	-666
12 Months or Longer, Fair Value	1,184	4,188
12 Months or Longer, Unrealized Losses	-40	-202
Total, Aggregate Fair Value	189,377	57,764
Total, Unrealized Losses	-5,675	-868
Fixed-maturity securities | Corporate Securities | Utilities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	42,328	20,143
Less than 12 Months, Unrealized Losses	-2,152	-191
12 Months or Longer, Fair Value	'	7
Total, Aggregate Fair Value	42,328	20,150
Total, Unrealized Losses	-2,152	-191
Fixed-maturity securities | Commercial mortgage-backed securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	50,984	23,223
Less than 12 Months, Unrealized Losses	-2,351	-141
12 Months or Longer, Fair Value	'	95
Total, Aggregate Fair Value	50,984	23,318
Total, Unrealized Losses	-2,351	-141
Fixed-maturity securities | Residential mortgage-backed securities, Agency backed securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	54,462	59,009
Less than 12 Months, Unrealized Losses	-1,613	-261
12 Months or Longer, Fair Value	229	25
12 Months or Longer, Unrealized Losses	-1	-1
Total, Aggregate Fair Value	54,691	59,034
Total, Unrealized Losses	-1,614	-262
Fixed-maturity securities | Residential mortgage-backed securities, Non-agency backed securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	639	815
Less than 12 Months, Unrealized Losses	-16	-6
12 Months or Longer, Fair Value	199	588
12 Months or Longer, Unrealized Losses	-14	-28
Total, Aggregate Fair Value	838	1,403
Total, Unrealized Losses	-30	-34
Fixed-maturity securities | Asset-Backed Securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	2,507	1,499
Less than 12 Months, Unrealized Losses	-2	-3
12 Months or Longer, Fair Value	'	4,232
12 Months or Longer, Unrealized Losses	'	-11
Total, Aggregate Fair Value	2,507	5,731
Total, Unrealized Losses	-2	-14
Preferred stocks	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	9,802	9,716
Less than 12 Months, Unrealized Losses	-821	-155
12 Months or Longer, Fair Value	6,089	5,724
12 Months or Longer, Unrealized Losses	-316	-326
Total, Aggregate Fair Value	15,891	15,440
Total, Unrealized Losses	-1,137	-481
Common Stocks	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	44,338	55,560
Less than 12 Months, Unrealized Losses	-463	-4,292
Total, Aggregate Fair Value	44,338	55,560
Total, Unrealized Losses	-463	-4,292
Short-term investments	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	11,379	'
Less than 12 Months, Unrealized Losses	-36	'
Total, Aggregate Fair Value	11,379	'
Total, Unrealized Losses	($36)	'

Amortized_Cost_and_Fair_Value_

Amortized Cost and Fair Value of Fixed-Maturity Portfolio by Contractual Time to Maturity (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than one year, amortized cost	$42,963	$32,760
One to five years, amortized cost	656,432	535,515
Five to ten years, amortized cost	712,217	641,036
More than 10 years, amortized cost	363,604	404,038
Mortgage and asset-backed securities, amortized cost	454,191	576,837
Total at end of period, amortized cost	2,229,407	2,190,186
Less than one year, fair value	43,745	33,329
One to five years, fair value	670,279	557,798
Five to ten years, fair value	720,259	687,720
More than 10 years, fair value	373,575	441,587
Mortgage and asset-backed securities, fair value	481,687	624,277
Total at end of period, fair value	2,289,545	2,344,711
Tower	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than one year, amortized cost	38,967	30,082
One to five years, amortized cost	614,572	489,939
Five to ten years, amortized cost	646,016	564,556
More than 10 years, amortized cost	301,473	346,410
Mortgage and asset-backed securities, amortized cost	379,624	495,249
Total at end of period, amortized cost	1,980,652	1,926,236
Less than one year, fair value	39,597	30,614
One to five years, fair value	626,489	510,523
Five to ten years, fair value	654,732	607,711
More than 10 years, fair value	310,890	379,045
Mortgage and asset-backed securities, fair value	404,062	536,255
Total at end of period, fair value	2,035,770	2,064,148
Reciprocal Exchanges	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than one year, amortized cost	3,996	2,678
One to five years, amortized cost	41,860	45,576
Five to ten years, amortized cost	66,201	76,480
More than 10 years, amortized cost	62,131	57,628
Mortgage and asset-backed securities, amortized cost	74,567	81,588
Total at end of period, amortized cost	248,755	263,950
Less than one year, fair value	4,148	2,715
One to five years, fair value	43,790	47,275
Five to ten years, fair value	65,527	80,009
More than 10 years, fair value	62,685	62,542
Mortgage and asset-backed securities, fair value	77,625	88,022
Total at end of period, fair value	$253,775	$280,563

Composition_of_Other_Invested_

Composition of Other Invested Assets (Detail) (Tower, USD $)	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]	'	'
Other invested assets	$77,038	$57,786
Limited partnerships, equity method	'	'
Schedule of Investments [Line Items]	'	'
Other invested assets	34,843	23,864
Real estate, amortized cost	'	'
Schedule of Investments [Line Items]	'	'
Other invested assets	7,645	7,422
Securities reported under the fair value option	'	'
Schedule of Investments [Line Items]	'	'
Other invested assets	30,250	25,000
Other	'	'
Schedule of Investments [Line Items]	'	'
Other invested assets	$4,300	$1,500

Financial_Instruments_at_Fair_

Financial Instruments at Fair Value among Levels (Detail) (USD $)	Jun. 30, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	$2,440,324		$2,495,719
Other invested assets	30,250	[1]	25,000	[2]
Interest rate swap contracts	-6,830		-9,016
Debt and equity securities sold, not yet purchased	-25,570		-17,101
Total investments and Other liabilities	2,438,174		2,494,602
Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	2,183,799		2,209,593
Total investments and Other liabilities	2,181,648		2,208,475
Reciprocal Exchanges	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	256,525		286,126
Total investments and Other liabilities	256,526		286,127
Level 1	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	137,400		146,258
Total investments and Other liabilities	137,400		146,258
Level 1 | Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	134,650		140,695
Level 1 | Reciprocal Exchanges	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	2,750		5,563
Level 2	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	2,302,924		2,349,461
Interest rate swap contracts	-6,830		-9,016
Debt and equity securities sold, not yet purchased	-25,570		-17,101
Total investments and Other liabilities	2,270,524		2,323,344
Level 2 | Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	2,016,748		2,042,780
Level 2 | Reciprocal Exchanges	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	253,776		280,564
Level 3	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Other invested assets	30,250	[1]	25,000	[2]
Total investments and Other liabilities	30,250		25,000
Level 3 | Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	30,250		25,000
Fixed-maturity securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	2,289,545		2,344,711
Fixed-maturity securities | U.S. Treasury Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	385,247		184,949
Fixed-maturity securities | U.S. Agency securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	105,323		102,777
Fixed-maturity securities | Municipal Bonds	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	587,391		686,043
Fixed-maturity securities | Corporate Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	729,899		746,665
Fixed-maturity securities | Commercial mortgage-backed securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	236,619		242,053
Fixed-maturity securities | Residential mortgage-backed securities, Agency backed securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	165,060		295,716
Fixed-maturity securities | Residential mortgage-backed securities, Non-agency backed securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	39,612		42,156
Fixed-maturity securities | Asset-Backed Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	40,394		44,352
Fixed-maturity securities | Level 2	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	2,289,545		2,344,711
Fixed-maturity securities | Level 2 | U.S. Treasury Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	385,247		184,949
Fixed-maturity securities | Level 2 | U.S. Agency securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	105,323		102,777
Fixed-maturity securities | Level 2 | Municipal Bonds	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	587,391		686,043
Fixed-maturity securities | Level 2 | Corporate Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	729,899		746,665
Fixed-maturity securities | Level 2 | Commercial mortgage-backed securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	236,619		242,053
Fixed-maturity securities | Level 2 | Residential mortgage-backed securities, Agency backed securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	165,060		295,716
Fixed-maturity securities | Level 2 | Residential mortgage-backed securities, Non-agency backed securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	39,612		42,156
Fixed-maturity securities | Level 2 | Asset-Backed Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	40,394		44,352
Equity securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	137,400		146,258
Equity securities | Level 1	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	137,400		146,258
Short-term investments	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	13,379		4,750
Short-term investments | Level 2	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	$13,379		$4,750
[1]	$30.3 million of the $77.0 million Other invested assets reported on the consolidated balance sheet at June 30, 2013 is reported at fair value. The remaining $46.7 million of Other invested assets is reported under the equity method of accounting or at amortized cost.
[2]	$25.0 million of the $57.8 million Other invested assets reported on the consolidated balance sheet at December 31, 2012 is reported at fair value. The remaining $32.8 million of Other invested assets is reported under the equity method of accounting or at amortized cost.

Financial_Instruments_at_Fair_1

Financial Instruments at Fair Value among Levels (Parenthetical) (Detail) (USD $)	Jun. 30, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Other invested assets, fair value	$30,250,000	[1]	$25,000,000	[2]
Other invested assets, amortized cost	46,700,000		32,800,000
Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Other invested asset	$77,038,000		$57,786,000
[1]	$30.3 million of the $77.0 million Other invested assets reported on the consolidated balance sheet at June 30, 2013 is reported at fair value. The remaining $46.7 million of Other invested assets is reported under the equity method of accounting or at amortized cost.
[2]	$25.0 million of the $57.8 million Other invested assets reported on the consolidated balance sheet at December 31, 2012 is reported at fair value. The remaining $32.8 million of Other invested assets is reported under the equity method of accounting or at amortized cost.

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012
Fair Value [Line Items]	'	'	'
Gross transfers out of Level 3	'	$0	$0
Gross transfers out of Level 1 into Level 2	0	0	0
Gross transfers out of Level 2 into Level 1	0	0	0
Net realized gains (losses) from fair value of debt and equity securities sold, not yet purchased	$700,000	$800,000	'
Tower | Other	'	'	'
Fair Value [Line Items]	'	'	'
Number of securities purchased	'	5	'

Summary_of_Changes_in_Level_Th

Summary of Changes in Level Three Assets Measured at Fair Value (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'	'	'
Beginning balance	$25,000	$24,914	$25,000	$25,000
Total gains (losses)-realized / unrealized - included in net income	'	86	'	'
Included in other comprehensive income (loss)	'	'	'	'
Purchases, issuances and settlements	5,250	'	5,250	'
Net transfers into (out of) Level 3	'	'	'	'
Ending balance	$30,250	$25,000	$30,250	$25,000

Reconciliation_of_Beginning_an

Reconciliation of Beginning and Ending Consolidated Balances for Unpaid Losses and Loss Adjustment Expense (Detail) (USD $)	3 Months Ended	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'
Balance at beginning of year	'	$1,895,679	$1,632,113
Less reinsurance recoverables on unpaid losses	-459,457	-459,457	-292,221
Liability for Unpaid Claims and Claims Adjustment Expense, Net	'	1,436,222	1,339,892
Net reserves, at fair value, of acquired entities	161,886	161,886	'
Incurred related to:	'	'	'
Current year	'	508,708	545,267
Prior years unfavorable/(favorable) development	326,700	326,916	72,001
Total incurred	'	835,624	617,268
Paid related to:	'	'	'
Current year	'	201,443	185,161
Prior years	'	370,007	344,343
Total paid	'	571,450	529,504
Net balance at end of period	1,862,282	1,862,282	1,427,656
Add reinsurance recoverables on unpaid losses	690,069	690,069	274,177
Net balance at end of year	2,552,351	2,552,351	1,701,833
Tower	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'
Balance at beginning of year	'	1,759,888	1,495,839
Less reinsurance recoverables on unpaid losses	-407,068	-407,068	-280,968
Liability for Unpaid Claims and Claims Adjustment Expense, Net	'	1,352,820	1,214,871
Net reserves, at fair value, of acquired entities	161,886	161,886	'
Incurred related to:	'	'	'
Current year	'	451,020	487,837
Prior years unfavorable/(favorable) development	325,600	326,749	78,254
Total incurred	'	777,769	566,091
Paid related to:	'	'	'
Current year	'	164,774	153,792
Prior years	'	359,786	313,400
Total paid	'	524,560	467,192
Net balance at end of period	1,767,915	1,767,915	1,313,770
Add reinsurance recoverables on unpaid losses	665,172	665,172	254,516
Net balance at end of year	2,433,087	2,433,087	1,568,286
Reciprocal Exchanges	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'
Balance at beginning of year	'	135,791	136,274
Less reinsurance recoverables on unpaid losses	-52,389	-52,389	-11,253
Liability for Unpaid Claims and Claims Adjustment Expense, Net	'	83,402	125,021
Incurred related to:	'	'	'
Current year	'	57,688	57,430
Prior years unfavorable/(favorable) development	'	167	-6,253
Total incurred	'	57,855	51,177
Paid related to:	'	'	'
Current year	'	36,669	31,369
Prior years	'	10,221	30,943
Total paid	'	46,890	62,312
Net balance at end of period	94,367	94,367	113,886
Add reinsurance recoverables on unpaid losses	24,897	24,897	19,661
Net balance at end of year	$119,264	$119,264	$133,547

Loss_and_Loss_Adjustment_Expen2

Loss and Loss Adjustment Expense - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Loss and loss adjustment expenses ratio	133.80%	76.00%	99.40%	70.10%	'
Prior years unfavorable/(favorable) development	$326,700,000	'	$326,916,000	$72,001,000	'
Percentage of loss reserves covered by reserve study	'	'	90.00%	'	'
Unfavorable/(favorable) development during the period	'	'	127,100,000	'	'
Unfavorable/(favorable) development during the period	'	'	835,624,000	617,268,000	'
Worker compensation discount amount	9,800,000	'	9,800,000	'	8,400,000
Unamortized reserve for risk premium	19,100,000	'	19,100,000	'	'
Amortization reserve for risk premium	'	'	2,200,000	'	'
Actuarial Gain Loss	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Unfavorable/(favorable) development during the period	'	'	201,100,000	'	'
Offset	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Unfavorable/(favorable) development during the period	'	'	900,000	'	'
Workers' Compensation	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Prior years unfavorable/(favorable) development	'	'	122,100,000	'	'
Commercial Automobile Liability	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Prior years unfavorable/(favorable) development	'	'	74,400,000	'	'
Commercial Package Liability	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Prior years unfavorable/(favorable) development	'	'	89,200,000	'	'
Other liability	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Prior years unfavorable/(favorable) development	'	'	42,600,000	'	'
Canopius Bermuda	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Unamortized reserve for risk premium	17,000,000	'	17,000,000	'	0
Tower	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Loss and loss adjustment expenses ratio	142.70%	77.30%	102.70%	71.10%	'
Prior years unfavorable/(favorable) development	325,600,000	'	326,749,000	78,254,000	'
Unfavorable/(favorable) development during the period	'	'	777,769,000	566,091,000	'
Tower | Specialty Insurance and Reinsurance	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Prior years unfavorable/(favorable) development	'	'	171,900,000	38,400,000	'
Tower | Commercial Insurance	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Prior years unfavorable/(favorable) development	'	'	163,600,000	35,600,000	'
Tower | Personal Insurance	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Prior years unfavorable/(favorable) development	'	'	-8,800,000	4,300,000	'
Tower | Workers' Compensation	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Unfavorable/(favorable) development during the period	'	'	'	39,000,000	'
Tower | Commercial Automobile Liability	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Unfavorable/(favorable) development during the period	'	'	'	22,000,000	'
Tower | Terminated Programs	'	'	'	'	'
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]	'	'	'	'	'
Unfavorable/(favorable) development during the period	'	'	'	$51,000,000	'

Shareholders_Equity_Additional

Shareholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		1 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Aug. 06, 2013	Mar. 13, 2013
						Restricted Stock	Restricted Stock	Restricted Stock	Restricted Stock	Subsequent Event	Canopius Bermuda
										Dividend Declared
Stockholders Equity Note [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Conversion ratio	1.133	1.133	1.133	1.133	'	'	'	'	'	'	'
Common shares, outstanding	57,429,099	'	57,429,099	'	43,513,678	'	'	'	'	'	14,025,737
Employee stock option exercises	2,674	0	2,674	0	'	'	'	'	'	'	'
Number of option, grants	'	'	'	'	'	2,333	0	242,626	363,894	'	'
Common stock purchased from employees to pay expected amount of tax liability	'	'	'	'	'	891	561	341,598	110,304	'	'
Number of shares, forfeitures	'	'	'	'	'	7,167	5,022	14,015	9,874	'	'
Treasury stock held	8,058	'	8,058	'	9,534,333	'	'	'	'	'	'
Stock repurchase program authorized amount	'	'	$50,000,000	'	'	'	'	'	'	'	'
Stock repurchase program, expiration date	'	'	30-Jun-13	'	'	'	'	'	'	'	'
Repurchase of common stock, shares	'	'	0	'	'	'	'	'	'	'	'
Share repurchase program authorization date	7-May-13	'	7-May-13	'	'	'	'	'	'	'	'
Dividends declared and paid	$9,500,000	$7,300,000	$16,676,000	$14,680,000	'	'	'	'	'	'	'
Dividends payable, amount per share	'	'	'	'	'	'	'	'	'	$0.17	'
Dividend payable date	'	'	'	'	'	'	'	'	'	20-Sep-13	'
Dividend record date	'	'	'	'	'	'	'	'	'	9-Sep-13	'
Historical dividend per share	'	'	$0.19	'	'	'	'	'	'	'	'

Summary_of_Changes_in_Accumula

Summary of Changes in Accumulated Other Comprehensive Income, by Component (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013
Components of Net Unrealized Investment Gains Losses Included in Accumulated Other Comprehensive Income Loss [Line Items]	'
Beginning Balance	$87,412
Other comprehensive income before reclassifications, net of tax	-71,210
Amounts reclassified from accumulated other comprehensive income, net of tax	-2,594
Net current period other comprehensive income	-73,804
Ending Balance	13,608
Beginning Balance	-5,860
Other comprehensive income before reclassifications, net of tax	1,406
Amounts reclassified from accumulated other comprehensive income, net of tax	1,084
Net current period other comprehensive income	2,490
Ending Balance	-3,370
Beginning Balance	1,204
Other comprehensive income before reclassifications, net of tax	-2,382
Amounts reclassified from accumulated other comprehensive income, net of tax	'
Net current period other comprehensive income	-2,382
Ending Balance	-1,178
Beginning Balance	82,756
Other comprehensive income before reclassifications, net of tax	-72,186
Amounts reclassified from accumulated other comprehensive income, net of tax	-1,510
Net current period other comprehensive income	-73,696
Ending Balance	$9,060

Reclassified_from_Accumulated_

Reclassified from Accumulated Other Comprehensive Income to Net Income (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Unrealized gains (losses) on available for sale securities, before income tax	($1,938)	$19	$4,529	$3,347
Unrealized gains (losses) on available for sale securities, net income tax	'	'	-2,594	'
Gains (losses) on cash flow hedges interest rate swaps, net of income taxes	'	'	-1,084	'
Other Net Unrealized Investment Gains and Losses	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Unrealized gains (losses) on available for sale securities, before income tax	'	'	-2,594	'
Income Tax Expense	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Unrealized gains (losses) on available for sale securities, Income tax expense	'	'	'	'
Interest Rate Swaps	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Gains (losses) on cash flow hedges interest rate swaps, net of income taxes	'	'	1,084	'
Interest Rate Swaps | Income Tax Expense	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Gains (losses) on cash flow hedges interest rate swaps, income tax expense	'	'	'	'
Interest Rate Swaps | Interest Expense	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Gains (losses) on cash flow hedges interest rate swaps, interest expense	'	'	$1,084	'

Borrowings_Detail

Borrowings (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
Credit facility	$70,000	$70,000
Subordinated debentures	235,058	235,058
Total	451,224	449,731
Credit facility	70,000	70,000
Subordinated debentures	240,010	232,678
Total	468,253	454,741
Convertible Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Convertible senior notes	146,166	144,673
Convertible senior notes	$158,243	$152,063

Debt_Additional_Information_De

Debt - Additional Information (Detail) (USD $)

3 Months Ended

6 Months Ended

1 Months Ended

6 Months Ended

1 Months Ended

1 Months Ended

Jun. 30, 2013

Mar. 31, 2013

Jun. 30, 2012

Jun. 30, 2013

Jun. 30, 2012

Apr. 03, 2013

Dec. 31, 2012

Sep. 30, 2010

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2012

Oct. 11, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Oct. 31, 2010

Oct. 31, 2010

Jun. 30, 2013

Dec. 31, 2012

Convertible Senior Notes

Convertible Senior Notes

Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges

Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges

Subsequent Event

Scenario, Forecast

Scenario, Forecast

Scenario, Forecast

Interest Rate Swaps

Interest Rate Swaps

Other liability

Other liability

Minimum

CastlePoint Reinsurance Company, Ltd.

Tower Reinsurance, Ltd.

Cash Flow Hedging

Interest Rate Swaps

Interest Rate Swaps

Minimum

Minimum

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest expense

$7,635,000

'

$7,902,000

$15,443,000

$16,513,000

'

'

'

$5,900,000

'

'

'

'

'

'

'

'

'

'

Subordinated debentures, carrying value

235,058,000

'

'

235,058,000

'

'

235,058,000

'

'

'

'

'

'

'

'

'

'

'

'

Notional amount, interest rate swap contracts

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

190,000,000

'

'

Interest rate swap contracts, terms

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'5 years

'

'

'

Interest rate range on swaps, minimum

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.10%

'

'

'

Interest rate range on swaps, maximum

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.90%

'

'

'

Interest rate swap contracts liabilities, fair value

6,830,000

'

'

6,830,000

'

'

9,016,000

'

'

'

'

'

'

'

'

'

'

6,800,000

9,000,000

Gain (loss) on Swaps designated as cash flow hedges reclassified from AOCI to interest expense

'

'

'

'

'

'

'

'

'

1,100,000

800,000

'

'

'

'

'

'

'

'

Collateral on deposit with the counterparty

6,900,000

'

'

6,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility agreement, borrowing capacity

'

'

'

'

'

220,000,000

'

'

'

'

'

70,000,000

'

'

'

'

'

'

'

Outstanding credit facility amount

70,000,000

'

'

70,000,000

'

'

70,000,000

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average interest rate

1.94%

'

'

1.94%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility agreement, maturity date

'

'

'

'

'

'

'

'

'

'

'

30-May-14

'

'

'

'

'

'

'

Credit facility covenant, Consolidated Net Worth

'

'

'

553,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, percentage of Consolidated Net Worth

90.00%

'

'

90.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, covenant increase as a percentage of any new capital

'

'

'

90.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, additional covenant increase as a percentage of net income above base

'

'

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, net income amount base for additional covenant increase

'

'

'

20,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, Debt to capitalization ratio limit

'

'

'

46.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, risk based capital ratio

'

'

'

'

'

'

'

'

'

'

'

'

175.00%

'

'

'

'

'

'

Credit facility covenant, consolidated statutory surplus

'

'

'

'

'

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

'

Credit facility covenant, percentage of required capital

'

'

'

'

'

'

'

'

'

'

'

'

'

150.00%

110.00%

'

'

'

'

Credit facility covenant, minimum statutory surplus

419,000,000

'

'

419,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility covenant, combined surplus

'

'

'

85.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Convertible senior notes principal amount

'

'

'

'

'

'

'

150,000,000

'

'

'

'

'

'

'

'

'

'

'

Interest rate on convertible senior note, percentage

'

'

'

'

'

'

'

5.00%

'

'

'

'

'

'

'

'

'

'

'

Maturity date of convertible senior notes

'

'

'

'

'

'

'

15-Sep-14

'

'

'

'

'

'

'

'

'

'

'

Frequency of interest payment, term

'

'

'

'

'

'

'

'Interest on the Notes is payable semi-annually in arrears on March 15 and September 15 of each year, commencing March 15, 2011.

'

'

'

'

'

'

'

'

'

'

'

First interest payment date

'

'

'

'

'

'

'

15-Mar-11

'

'

'

'

'

'

'

'

'

'

'

Earliest conversion date for notes

'

'

'

'

'

'

'

15-Mar-14

'

'

'

'

'

'

'

'

'

'

'

Conversion rate of shares of common stock per principal amount of notes

'

'

'

'

'

'

'

'

42.369

'

'

'

'

'

'

'

'

'

'

Principal amount of Notes

'

'

'

'

'

'

'

'

1,000

'

'

'

'

'

'

'

'

'

'

Initial conversion price

'

'

'

'

'

'

'

'

$23.60

'

'

'

'

'

'

'

'

'

'

Debt conversion term

'

'

'

'

'

'

'

'

'The adjusted conversion rate at June 30, 2013 is 42.3690 shares of common stock per $1,000 principal amount of the Notes (equivalent to a conversion price of $23.60 per share), subject to further adjustment upon the occurrence of certain events, including the following: if Tower issues shares of common stock as a dividend or distribution on shares of the common stock , or if Tower effects a share split or share combination; if Tower issues to all or substantially all holders of common stock any rights, options or warrants entitling them, for a period of not more than 45 calendar days after the announcement date of such issuance, to subscribe for or purchase shares of the common stock at a price per share that is less than the average of the last reported sales price of the common stock for the ten consecutive trading day period ending on the date of announcement of such issuance; if Tower distributes shares of its capital stock, other indebtedness, other assets or property of Tower or rights, options or warrants to acquire capital stock or other securities of Tower, to all or substantially all holders of capital stock; if any cash dividend or distribution is made to all or substantially all holders of the common stock, other than a regular quarterly cash dividend that does not exceed $0.110 per share; if Tower makes a payment in respect of a tender offer or exchange offer for common stock, and the cash and value of any other consideration included in the payment per share of common stock exceeds the last reported sale price of the common stock on the trading day next succeeding the last day on which the tenders or exchange may be made.

'

'

'

'

'

'

'

'

'

'

Effective interest rate on convertible senior note

'

'

'

'

'

'

'

'

7.20%

'

'

'

'

'

'

'

'

'

'

Transaction costs associated with equity component

'

'

'

'

'

'

'

'

400,000

'

'

'

'

'

'

'

'

'

'

Proceeds from issuance of note hedge

'

2,400,000

'

2,380,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments for warrants

'

1,000,000

'

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Tax adjustment recorded in paid-in-capital

'

$800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amounts_Recorded_for_Notes_Det

Amounts Recorded for Notes (Detail) (Convertible Senior Notes, USD $)	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Convertible Senior Notes	'	'
Liability component	'	'
Outstanding principal	$150,000	$150,000
Unamortized OID	-3,834	-5,327
Liability component	146,166	144,673
Equity component, net of tax	$7,469	$7,469

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail)	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2013	Mar. 13, 2013
			2008 LTEP	2013 LTIP	Canopius Group Limited
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'
Maximum Share based awards authorized	'	'	2,325,446	2,150,000	'
Shares available for future grants	'	'	30,376	2,147,531	'
Number of shares, vested	'	'	'	'	525,548
Conversion ratio	1.133	1.133	'	'	'

Analysis_of_Restricted_Stock_A

Analysis of Restricted Stock Activity (Detail) (Restricted Stock, USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Restricted Stock	'	'	'	'
Number of Shares	'	'	'	'
Number of Shares, Beginning Balance	'	'	1,015,902	1,120,091
Number of Shares, Granted	2,333	0	242,626	363,894
Number of Shares, Vested	'	'	-953,242	-439,734
Number of Shares, Forfeitures	-7,167	-5,022	-14,015	-9,874
Number of Shares, Ending Balance	291,271	1,034,377	291,271	1,034,377
Weighted Average Grant Date Fair Value	'	'	'	'
Weighted Average Grant Date Fair Value, Beginning Balance	'	'	$20.19	$20.69
Weighted Average Grant Date Fair Value, Granted	'	'	$18.09	$20.37
Weighted Average Grant Date Fair Value, Vested	'	'	$20.43	$21.07
Weighted Average Grant Date Fair Value, Forfeitures	'	'	$19.26	$20.83
Weighted Average Grant Date Fair Value, Ending Balance	$17.68	$20.38	$17.68	$20.38

Analysis_of_Stock_Option_Activ

Analysis of Stock Option Activity (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Number of Shares	'	'	'	'
Number of Shares Outstanding, Beginning Balance	'	'	969,307	969,315
Number of Shares, Exercised	-2,674	0	-2,674	0
Number of Shares, Forfeitures and expirations	'	'	-7,657	'
Number of Shares Outstanding, Ending Balance	958,976	969,315	958,976	969,315
Number of Shares Exercisable, Ending Balance	958,976	969,315	958,976	969,315
Average Exercise Price	'	'	'	'
Average Exercise Price Outstanding, Beginning Balance	'	'	$17.78	$17.78
Average Exercise Price, Exercised	'	'	$16.48	'
Average Exercise Price, Forfeitures and expirations	'	'	$17.72	'
Average Exercise Price Outstanding, Ending Balance	$17.78	$17.78	$17.78	$17.78
Average Exercise Price Exercisable, Ending Balance	$17.78	$17.78	$17.78	$17.78

Analysis_of_Stock_Based_Compen

Analysis of Stock Based Compensation Expense (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Weighted average years over which expense will be recognized	'3 years 7 months 6 days	'2 years 6 months
Restricted Stock	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Expense, net of tax	8,204	896
Value of shares vested	21,042	8,576
Value of unvested shares	5,974	19,257
Unrecognized compensation expense	5,974	12,791
Employee Stock Option	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Intrinsic value of outstanding options	3,471	1,632
Intrinsic value of vested outstanding options	3,471	1,632

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Taxes [Line Items]	'	'	'	'
Income (loss) before income taxes	($508,471,000)	($25,291,000)	($508,425,000)	$6,110,000
Net deferred tax asset	134,500,000	'	134,500,000	'
Prior years unfavorable/(favorable) development	326,700,000	'	326,916,000	72,001,000
Goodwill impairment charge	214,049,000	'	214,049,000	'
Effective tax rate	0.40%	'	0.70%	'
Tower	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Net deferred tax asset	141,500,000	'	141,500,000	'
Prior years unfavorable/(favorable) development	325,600,000	'	326,749,000	78,254,000
U.S. | Tower	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Income (loss) before income taxes	-493,800,000	-61,300,000	-509,300,000	'
Prior years unfavorable/(favorable) development	149,700,000	'	'	'
Goodwill impairment charge	185,900,000	'	'	'
U.S. | Tower | Net Operating Loss Carryforwards	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Deferred tax inventory	111,000,000	'	111,000,000	'
Income Tax Expense (Benefit)	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Deferred tax assets, valuation allowance	113,900,000	'	113,900,000	'
Other Comprehensive Income (Loss)	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Deferred tax assets, valuation allowance	25,800,000	'	25,800,000	'
Non Life Insurance Premiums	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Percentage of excise tax rate	'	'	4.00%	'
Life Insurance and Reinsurance Premiums	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Percentage of excise tax rate	'	'	1.00%	'
Federal	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Excise tax	'	'	$6,300,000	'

Earnings_Loss_per_Share_Additi

Earnings (Loss) per Share - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share Disclosure [Line Items]	'	'	'	'
Conversion ratio	1.133	1.133	1.133	1.133
Options and other common stock equivalents excluded from computation of diluted earnings per share	958,980	969,310	958,980	190,500

Computation_of_Earnings_Per_Sh

Computation of Earnings Per Share (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Numerator	'	'	'	'
Net income (loss) attributable to Tower Group International, Ltd.	($507,342)	($16,809)	($494,425)	$2,356
Less: Allocation of income for unvested participating restricted stock	'	'	'	'
Less: Dividends on unvested participating restricted stock	-48	-173	-215	-347
Net income available to common shareholders - Basic	-507,390	-16,982	-494,640	2,009
Reallocation of income for unvested participating restricted stock	'	'	'	'
Net income available to common shareholders - Diluted	($507,390)	($16,982)	($494,640)	$2,009
Denominator	'	'	'	'
Basic earning per share denominator	57,135	43,289	51,487	43,340
Effect of dilutive securities	'	'	'	'
Diluted earnings per share denominator	57,135	43,289	51,487	43,410
Common stock:	'	'	'	'
Distributed earnings	$0.17	$0.17	$0.34	$0.34
Undistributed earnings	($9.05)	($0.56)	($9.95)	($0.29)
Total	($8.88)	($0.39)	($9.61)	$0.05
Earnings (loss) per share attributable to Tower Group International, Ltd. - Diluted	($8.88)	($0.39)	($9.61)	$0.05

Statutory_Financial_Informatio1

Statutory Financial Information - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended			6 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013	Oct. 31, 2013	Jun. 30, 2013
					Tower Reinsurance, Ltd.	Tower Reinsurance, Ltd.	Tower Reinsurance, Ltd.
							New Reinsurance Program
							Agreement
Statutory Accounting Practices [Line Items]	'	'	'	'	'	'	'
Adverse loss reserve development from loss portfolio transaction	$326,700,000	$326,916,000	$72,001,000	'	$175,000,000	'	'
Reinsurance capital reserve	'	'	'	'	8,300,000	'	'
Amount required to be collateralized against adverse loss reserve development	657,275,000	657,275,000	'	98,581,000	175,000,000	'	'
Unencumbered liquid assets	'	'	'	'	$96,000,000	$79,000,000	'
Number of reinsurance treaties commuted	'	'	'	'	'	'	2

Business_Segments_Results_Deta

Business Segments Results (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues	'	'	'	'
Premiums earned	$418,364	$460,153	$840,250	$880,311
Ceding commission revenue	11,933	10,080	26,084	15,243
Policy billing fees	3,321	3,000	6,471	6,134
Total revenues	460,518	506,392	937,001	972,615
Expenses	'	'	'	'
Loss and loss adjustment expenses	559,892	349,775	835,624	617,268
Total expenses	762,778	531,683	1,239,343	966,505
Reciprocal Exchanges	'	'	'	'
Revenues	'	'	'	'
Total revenues	49,100	49,200	96,400	99,400
Expenses	'	'	'	'
Total expenses	48,300	48,800	106,900	96,000
Commercial Insurance	'	'	'	'
Expenses	'	'	'	'
Loss and loss adjustment expenses	249,906	155,395	373,293	272,239
Underwriting expenses	66,614	63,832	129,383	128,245
Total expenses	316,520	219,227	502,676	400,484
Underwriting profit (loss)	-152,567	-24,776	-159,294	-18,708
Specialty Insurance and Reinsurance	'	'	'	'
Expenses	'	'	'	'
Loss and loss adjustment expenses	248,466	125,814	321,442	210,408
Underwriting expenses	56,772	50,122	106,915	88,851
Total expenses	305,238	175,936	428,357	299,259
Underwriting profit (loss)	-179,499	-27,453	-169,607	-38,743
Personal Insurance	'	'	'	'
Expenses	'	'	'	'
Loss and loss adjustment expenses	61,520	68,566	140,889	134,621
Underwriting expenses	63,709	56,164	121,696	107,617
Total expenses	125,229	124,730	262,585	242,238
Underwriting profit (loss)	14,035	5,569	3,426	17,158
Personal Insurance | Tower	'	'	'	'
Expenses	'	'	'	'
Underwriting profit (loss)	14,139	9,376	16,156	21,213
Personal Insurance | Reciprocal Exchanges	'	'	'	'
Expenses	'	'	'	'
Underwriting profit (loss)	-104	-3,807	-12,730	-4,055
Operating Segments	'	'	'	'
Revenues	'	'	'	'
Total revenues	428,956	473,233	868,143	901,688
Operating Segments | Commercial Insurance	'	'	'	'
Revenues	'	'	'	'
Premiums earned	170,832	193,793	348,827	381,651
Ceding commission revenue	-8,301	-732	-8,237	-2,778
Policy billing fees	1,422	1,390	2,792	2,903
Total revenues	163,953	194,451	343,382	381,776
Operating Segments | Specialty Insurance and Reinsurance	'	'	'	'
Revenues	'	'	'	'
Premiums earned	122,211	143,857	251,999	253,834
Ceding commission revenue	3,528	4,626	6,751	6,682
Total revenues	125,739	148,483	258,750	260,516
Operating Segments | Personal Insurance	'	'	'	'
Revenues	'	'	'	'
Premiums earned	125,321	122,503	239,424	244,826
Ceding commission revenue	12,044	6,186	22,908	11,339
Policy billing fees	1,899	1,610	3,679	3,231
Total revenues	$139,264	$130,299	$266,011	$259,396

Reconciliation_of_Revenue_by_S

Reconciliation of Revenue by Segment to Consolidated Revenues (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'	'
Net investment income	$28,402	$31,781	$58,719	$65,724
Net realized gains (losses) on investments, including other-than-temporary impairments	-2,034	19	4,817	3,347
Corporate and other	5,194	1,359	5,322	1,856
Revenues	460,518	506,392	937,001	972,615
Operating Segments	'	'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'	'
Revenues	428,956	473,233	868,143	901,688
Operating Segments | Commercial Insurance	'	'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'	'
Revenues	163,953	194,451	343,382	381,776
Operating Segments | Specialty Insurance and Reinsurance	'	'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'	'
Revenues	125,739	148,483	258,750	260,516
Operating Segments | Personal Insurance	'	'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'	'
Revenues	$139,264	$130,299	$266,011	$259,396

Reconciliation_of_Results_of_I

Reconciliation of Results of Individual Segments to Consolidated Income Before Income Taxes (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Net investment income	$28,402	$31,781	$58,719	$65,724
Net realized gains on investments, including other-than-temporary impairments	-2,034	19	4,817	3,347
Corporate and other	-2,297	-1,809	-5,239	-4,173
Acquisition-related transaction costs	-665	-720	-19,721	-1,982
Interest expense	-7,635	-7,902	-15,443	-16,513
Goodwill impairment	-214,049	'	-214,049	'
Equity income in unconsolidated affiliate	7,838	'	7,966	'
Income (loss) before income taxes	-508,471	-25,291	-508,425	6,110
Commercial Insurance	'	'	'	'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Underwriting profit (loss)	-152,567	-24,776	-159,294	-18,708
Goodwill impairment	'	'	-214,049	'
Specialty Insurance and Reinsurance	'	'	'	'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Underwriting profit (loss)	-179,499	-27,453	-169,607	-38,743
Personal Insurance	'	'	'	'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Underwriting profit (loss)	$14,035	$5,569	$3,426	$17,158

Contingencies_Additional_Infor

Contingencies - Additional Information (Detail) (Subsequent Event, USD $)	1 Months Ended
In Millions, unless otherwise specified	Oct. 18, 2013
Subsequent Event	'
Loss Contingencies [Line Items]	'
Contingencies, damages sought	$150

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	Apr. 03, 2013	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013	Oct. 11, 2013	Aug. 19, 2013	Oct. 01, 2013	Oct. 01, 2013	Oct. 01, 2013
In Millions, unless otherwise specified		Specialty Insurance and Reinsurance	Specialty Insurance and Reinsurance	Commercial Insurance	Commercial Insurance	Subsequent Event	Subsequent Event	Subsequent Event	Subsequent Event	Subsequent Event
								Tower Insurance Company of New York	Tower Insurance Company of New York	Tower Insurance Company of New York
								Arch	Hannover	Southport Re
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'	'	'
Gain on agreement termination	'	'	'	'	'	'	$5	'	'	'
Credit facility agreement, borrowing capacity	220	'	'	'	'	70	'	'	'	'
Credit facility agreement, maturity date	'	'	'	'	'	30-May-14	'	'	'	'
Quota share reinsurance cede, percentage	'	'	'	'	'	'	'	17.50%	14.00%	30.00%
Net written premiums	'	$103.70	$306.60	$169.10	$343.60	'	'	'	'	'