Tower Group International (TWGP) 10-Q 12 Feb 14 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Feb. 10, 2014
Document Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
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	'	57,350,877

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Available-for-sale investments, at fair value:	'	'
Fixed-maturity securities	$1,874,133	$2,344,711
Total investments	2,085,488	2,553,505
Cash and cash equivalents	379,608	102,269
Investment income receivable	19,965	25,332
Investment in unconsolidated affiliate	76,785	71,894
Premiums receivable	387,658	412,045
Reinsurance recoverable on paid losses	85,668	17,609
Reinsurance recoverable on unpaid losses	594,763	459,457
Prepaid reinsurance premiums	217,916	63,923
Deferred acquisition costs, net	149,836	181,198
Intangible assets	80,215	106,768
Goodwill	0	241,458
Funds held by reinsured companies	191,901	137,545
Other assets	362,757	338,769
Total assets	4,632,560	4,711,772
Liabilities	'	'
Loss and loss adjustment expenses	2,098,481	1,895,679
Unearned premium	959,675	921,271
Reinsurance balances payable	385,123	40,569
Funds held under reinsurance agreements	215,953	98,581
Other liabilities	278,635	296,960
Deferred income taxes	20,050	24,763
Debt	451,991	449,731
Total liabilities	4,409,908	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 57,427,243 and 43,513,678 shares outstanding)	574	530
Treasury stock (9,914 and 9,534,333 shares)	-23	-181,435
Paid-in-capital	814,927	780,036
Accumulated other comprehensive income	-7,685	82,756
Retained earnings (accumulated deficit)	-600,039	268,171
Tower Group International, Ltd. shareholders' equity	207,754	950,058
Noncontrolling interests	14,898	34,160
Total shareholders' equity	222,652	984,218
Total liabilities and shareholders' equity	4,632,560	4,711,772
Tower	'	'
Available-for-sale investments, at fair value:	'	'
Fixed-maturity securities	1,624,312	2,064,148
Equity securities	105,383	140,695
Short-term investments	5,889	4,750
Other invested assets	97,559	57,786
Liabilities	'	'
Loss and loss adjustment expenses	1,986,541	1,759,888
Reciprocal Exchanges	'	'
Available-for-sale investments, at fair value:	'	'
Fixed-maturity securities	249,821	280,563
Equity securities	2,524	5,563
Cash and cash equivalents	11,656	9,782
Investment income receivable	2,428	2,610
Premiums receivable	48,756	44,285
Reinsurance recoverable on paid losses	4,460	682
Reinsurance recoverable on unpaid losses	22,152	52,389
Prepaid reinsurance premiums	22,503	17,803
Deferred acquisition costs, net	10,796	11,364
Intangible assets	6,467	6,854
Other assets	1,877	1,559
Liabilities	'	'
Loss and loss adjustment expenses	111,940	135,791
Unearned premium	110,361	103,216
Reinsurance balances payable	4,095	6,979
Funds held under reinsurance agreements	0	500
Other liabilities	17,855	21,346
Deferred income taxes	$19,720	$19,719

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Fixed-maturity securities, amortized cost	$1,831,964	$2,190,186
Cash and cash equivalents	379,608	102,269
Investment income receivable	19,965	25,332
Premiums receivable	387,658	412,045
Reinsurance recoverable on paid losses	85,668	17,609
Reinsurance recoverable on unpaid losses	594,763	459,457
Prepaid reinsurance premiums	217,916	63,923
Deferred acquisition costs, net	149,836	181,198
Intangible assets	80,215	106,768
Other assets	362,757	338,769
Loss and loss adjustment expenses	2,098,481	1,895,679
Unearned premium	959,675	921,271
Reinsurance balances payable	385,123	40,569
Funds held under reinsurance agreements	215,953	98,581
Other liabilities	278,635	296,960
Deferred income taxes	20,050	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	57,427,243	43,513,678
Treasury stock, shares	9,914	9,534,333
Tower	'	'
Fixed-maturity securities, amortized cost	1,585,624	1,926,236
Equity securities, cost	100,907	144,204
Short-term investments, cost	5,925	4,749
Loss and loss adjustment expenses	1,986,541	1,759,888
Reciprocal Exchanges	'	'
Fixed-maturity securities, amortized cost	246,340	263,950
Equity securities, cost	2,751	5,144
Cash and cash equivalents	11,656	9,782
Investment income receivable	2,428	2,610
Premiums receivable	48,756	44,285
Reinsurance recoverable on paid losses	4,460	682
Reinsurance recoverable on unpaid losses	22,152	52,389
Prepaid reinsurance premiums	22,503	17,803
Deferred acquisition costs, net	10,796	11,364
Intangible assets	6,467	6,854
Other assets	1,877	1,559
Loss and loss adjustment expenses	111,940	135,791
Unearned premium	110,361	103,216
Reinsurance balances payable	4,095	6,979
Funds held under reinsurance agreements	0	500
Other liabilities	17,855	21,346
Deferred income taxes	$19,720	$19,719

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues	'	'	'	'
Net premiums earned	$368,293	$430,713	$1,208,543	$1,311,024
Ceding commission revenue	28,195	7,703	54,279	22,946
Insurance services revenue	-142	808	518	2,664
Policy billing fees	2,796	3,133	9,267	9,267
Net investment income	25,632	31,389	84,351	97,113
Net realized investment gains (losses):	'	'	'	'
Other-than-temporary impairments	-4,527	-1,727	-9,672	-6,973
Portion of loss recognized in other comprehensive income	335	'	335	286
Other net realized investment gains	22,320	2,872	32,282	11,179
Total net realized investment gains (losses)	18,128	1,145	22,945	4,492
Total revenues	442,902	474,891	1,379,903	1,447,506
Expenses	'	'	'	'
Loss and loss adjustment expenses	383,778	256,096	1,219,402	873,364
Commission expense	101,742	87,527	297,596	263,098
Other operating expenses	110,187	85,404	282,888	240,575
Acquisition-related transaction costs	559	2,679	20,280	4,661
Interest expense	8,008	8,224	23,451	24,737
Total expenses	604,274	439,930	1,843,617	1,406,435
Other income (expense)	'	'	'	'
Equity income in unconsolidated affiliate	-3,194	'	4,772	'
Goodwill and fixed asset impairment	-183,162	'	-397,211	'
Other	5,000	'	5,000	'
Income (loss) before income taxes	-342,728	34,961	-851,153	41,071
Income tax expense (benefit)	1,404	9,014	-2,116	9,320
Net income (loss)	-344,132	25,947	-849,037	31,751
Less: Net income (loss) attributable to Noncontrolling interests	3,502	4,318	-6,978	7,766
Net income (loss) attributable to Tower Group International, Ltd.	($347,634)	$21,629	($842,059)	$23,985
Earnings (loss) per share attributable to Tower Group International, Ltd. shareholders:	'	'	'	'
Basic	($6.08)	$0.50	($15.79)	$0.54
Diluted	($6.08)	$0.50	($15.79)	$0.54
Weighted average common shares outstanding:	'	'	'	'
Basic	57,138	42,449	53,338	43,045
Diluted	57,138	42,476	53,338	43,130
Dividends declared and paid per common share	$0.17	$0.17	$0.50	$0.50

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income (loss)	($344,132)	$25,947	($849,037)	$31,751
Other comprehensive income (loss) before tax	'	'	'	'
Gross unrealized investment holding gains (losses) arising during periods	-20	39,543	-81,354	73,128
Less: Reclassification adjustment for investment (gains) losses included in net income	-18,751	-1,145	-23,280	-2,297
Portion of other-than-temporary impairment losses recognized in other comprehensive income	335	'	335	-286
Cumulative translation adjustment	3,742	'	78	'
Deferred gain (loss) on cash flow hedge	-2,322	-906	1,496	-4,492
Other comprehensive income (loss) before tax	-17,016	37,492	-102,725	66,053
Income tax benefit (expense) related to items of other comprehensive income (loss)	'	-12,942	'	-21,295
Other comprehensive income (loss), net of income tax	-17,016	24,550	-102,725	44,758
Comprehensive income (loss)	-361,148	50,497	-951,762	76,509
Less: Comprehensive income (loss) attributable to Noncontrolling interests	3,230	8,609	-19,262	18,643
Comprehensive income (loss) attributable to Tower Group International, Ltd.	($364,378)	$41,888	($932,500)	$57,866

Consolidated_Statements_Of_Sha

Consolidated Statements Of 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	-21,874	'	'	'	'	-21,874	'
Stock based compensation (in shares)	'	377	'	'	'	'	'
Stock based compensation	4,447	3	-2,260	6,704	'	'	'
Repurchase of common stock	-20,987	'	-20,987	'	'	'	'
Net income (loss)	31,751	'	'	'	'	23,985	7,766
Transfer of assets to Reciprocal Exchange	'	'	'	-1,778	'	'	1,778
Other comprehensive income (loss)	44,758	'	'	'	33,881	'	10,877
Balance at Sep. 30, 2012	1,075,226	529	-181,432	777,803	96,934	333,591	47,801
Balance (in shares) at Sep. 30, 2012	'	53,003	'	'	'	'	'
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	-26,151	'	'	'	'	-26,151	'
Stock based compensation (in shares)	'	245	'	'	'	'	'
Stock based compensation	8,459	3	-5,876	14,332	'	'	'
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 Canopius Merger Transaction	'	-99	187,288	-187,189	'	'	'
Termination of convertible senior notes hedge and warrants	541	'	'	541	'	'	'
Net income (loss)	-849,037	'	'	'	'	-842,059	-6,978
Other comprehensive income (loss)	-102,725	'	'	'	-90,441	'	-12,284
Balance at Sep. 30, 2013	$222,652	$574	($23)	$814,927	($7,685)	($600,039)	$14,898
Balance (in shares) at Sep. 30, 2013	'	57,437	'	'	'	'	'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash flows provided by (used in) operating activities:	'	'
Net income (loss)	($849,037)	$31,751
Adjustments to reconcile net income to net cash provided by (used in) operations:	'	'
Gain on investment in acquired unconsolidated affiliate	-4,772	'
Net realized investment (gains) losses	-22,945	-4,492
Depreciation and amortization	50,308	25,103
Goodwill and fixed asset impairment	397,211	'
Amortization of bond premium or discount	8,739	8,393
Amortization of restricted stock	12,956	6,707
Deferred income taxes	1,945	301
Excess tax benefits from share-based payment arrangements	'	'
Changes in operating assets and liabilities:	'	'
Investment income receivable	5,367	-3,406
Premiums receivable	24,387	39,237
Reinsurance recoverable	265,362	10,068
Prepaid reinsurance premiums	-1,562	-8,783
Deferred acquisition costs, net	37,180	-20,731
Funds held by reinsured companies	644,463	-54,598
Other assets	44,896	-25,236
Loss and loss adjustment expenses	-427,811	62,553
Unearned premium	-131,559	34,119
Reinsurance balances payable	344,554	56
Funds held under reinsurance agreements	-443,342	-7,916
Other liabilities	-51,110	33,470
Net cash flows provided by (used in) operations	-94,770	126,596
Cash flows provided by (used in) investing activities:	'	'
Cash acquired in Canopius Merger Transaction	134,741	'
Purchase of fixed assets	-30,880	-33,085
Investment in unconsolidated affiliate	'	-71,512
Purchase of fixed-maturity securities	-1,065,148	-1,288,117
Purchase of equity securities	-941,478	-1,202,074
Short-term investments, net	25,844	-4,748
Purchase of other invested assets	-39,773	-10,018
Sale of fixed-maturity securities	1,256,695	1,286,634
Maturity of fixed-maturity securities	133,033	142,229
Sale of equity securities	970,837	1,149,473
Other	'	-5,229
Change in restricted cash	-41,117	'
Net cash flows provided by (used in) investing activities	402,754	-36,447
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	'	284
Treasury stock acquired-net employee share-based compensation	-5,876	-2,259
Repurchase of Common Stock	'	-20,987
Dividends paid	-26,151	-21,874
Net cash flows provided by (used in) financing activities	-30,645	-24,833
Increase (decrease) in cash and cash equivalents	277,339	65,316
Cash and cash equivalents, beginning of period	102,269	114,098
Cash and cash equivalents, end of period	$379,608	$179,414

Nature_of_Business

Nature of Business	9 Months Ended
	Sep. 30, 2013
Nature of Business	'
	Note 1—Nature of Business
	Tower Group International, Ltd. (the “Company” or “Tower”) offers a broad range of commercial, assumed reinsurance 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 “Canopius 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 Canopius Merger Transaction. See “Note 4 – Canopius Merger Transaction” for further discussion of the Canopius Merger Transaction and the Company’s succession to TGI as registrant. As stated above, the registrant is deemed to be the successor to Tower Group, Inc. pursuant to Rule 12g-3(a) under the Exchange Act and, following the consummation of the merger described above by the registrant and Tower Group, Inc., the consolidated financial statements of Tower Group, Inc. for the periods through March 13, 2013, closing date of the merger, became the registrant’s consolidated statements for the same periods. Accordingly, as used herein, unless the context requires otherwise, references to “Tower”, the “Company”, “we”, “us”, or “our” (i) with respect to any period, event or occurrence prior to March 13, 2013, are to Tower Group, Inc. and (ii) with respect to any subsequent period, event or occurrence, are to Tower Group International, Ltd., and, in each case include the Company’s insurance subsidiaries, managing general agencies and management companies.
	Significant Business Developments and Risks and Uncertainties
	Proposed Merger with ACP Re
	On January 3, 2014, Tower entered into an Agreement and Plan of Merger (“ACP Re Merger Agreement”) with ACP Re Ltd. (“ACP Re”), and a wholly-owned subsidiary of ACP Re (“Merger Sub”), pursuant to which, subject to the satisfaction or waiver of the conditions therein, it is expected that Merger Sub will merge with and into Tower, with Tower as the surviving corporation in the merger and a wholly owned subsidiary of ACP Re. The transaction is expected to close by the summer of 2014, subject to the satisfaction or waiver of the closing conditions contained in the ACP Re Merger Agreement. ACP Re is a Bermuda based reinsurance company. The controlling shareholder of ACP Re is a trust established by the founder of AmTrust Financial Services, Inc. (“AmTrust”), National General Holdings Corporation (“NGHC”) and Maiden Holdings, Ltd.
	Pursuant to the terms of the ACP Re Merger Agreement, at the effective time of the merger, each outstanding share of Tower’s common stock, par value $0.01 per share, following the settlement of all outstanding equity awards, will be converted into the right to receive $3.00 in cash, with an aggregate value of approximately $172.1 million.
	Each of the parties has made representations and warranties in the ACP Re Merger Agreement. Tower has agreed to certain covenants and agreements, including, among others, (i) to conduct its business in the ordinary course of business, consistent with past practice, during the period between the execution of the ACP Re Merger Agreement and the closing of the merger, (ii) not to solicit alternate transactions, subject to a customary “fiduciary out” provision which allows Tower under certain circumstances to provide information to and participate in discussions with third parties with respect to unsolicited alternative acquisition proposals that Tower’s Board of Directors has determined, in its good faith judgment, is appropriate in furtherance of the best interests of Tower, and (iii) to call and hold a special shareholders’ meeting and recommend adoption of the ACP Re Merger Agreement.
	Concurrently with the execution of the ACP Re Merger Agreement, several subsidiaries of Tower have entered into two Cut Through Reinsurance Agreements, pursuant to which a subsidiary of AmTrust and a subsidiary of NGHC will provide 100% quota share reinsurance and a cut through endorsement to cover all eligible new and renewal commercial and personal lines business, respectively, and at their option, losses incurred on or after January 1, 2014 on not less than 60% of the in-force business. Tower received confirmation on January 16, 2014 from AmTrust and NGHC that they would exercise such option to reinsure on a cut through basis losses incurred on or after January 1, 2014 under in-force policies with respect to (1) in the case of AmTrust, a significant majority of Tower’s unearned premium reserves as of December 31, 2013 with respect to its ongoing commercial lines business, and (2) in the case of NGHC, 100% of Tower’s unearned premium reserves as of December 31, 2013 with respect to its personal lines segment business. Tower will receive a 20% ceding commission from AmTrust or NGHC on all Tower premiums that are subject to the Cut Through Reinsurance Agreements. Concurrently with the closing of the ACP Re Merger Agreement, ACP Re intends to sell certain of Tower’s commercial statutory entities to an affiliate of Amtrust, and certain of Tower’s personal lines statutory entities to an affiliate of National General Insurance Company.
	Concurrently with the execution of the ACP Re Merger Agreement, the controlling shareholder of ACP Re has provided to Tower a guarantee for the payment of the merger consideration, effective upon the closing of the merger.
	The ACP Re Merger Agreement was unanimously approved by the respective Boards of Directors of ACP Re and Tower, and is conditioned, among other things, on: (i) the approval of Tower’s shareholders, (ii) receipt of governmental approvals, including antitrust and insurance regulatory approvals (On January 30, 2014, the Company was granted early termination of the Hart-Scott-Rodino waiting period), (iii) the absence of any law, order or injunction prohibiting the merger, (iv) the accuracy of each party’s representations and warranties (subject to customary materiality qualifiers), and (v) each party’s compliance with its covenants and agreements contained in the ACP Re Merger Agreement. In addition, ACP Re’s obligation to consummate the merger is subject to the non-occurrence of any material adverse effect on Tower, as well as the absence of any insolvency-related event affecting Tower. The transaction is also conditioned on holders of not more than 15% of Tower’s common stock dissenting to the merger.
	There is no financing condition to consummation of the transactions contemplated by the ACP Re Merger Agreement.
	The ACP Re Merger Agreement provides certain termination rights for each of Tower and ACP Re, and further provides that upon termination of the ACP Re Merger Agreement, under various circumstances, Tower will be obligated to reimburse ACP Re for certain of its transaction expenses, subject to a cap of $2 million, and to pay ACP Re a termination fee of $8.18 million, net of any transaction expenses it has reimbursed.
	Michael H. Lee, the former Chairman, President and Chief Executive Officer of Tower, who beneficially owned approximately 4.2% of the issued and outstanding common stock of Tower as of January 3, 2014, has entered into a support agreement pursuant to which he has agreed to vote his shares in favor of the merger.
	Loss reserve strengthening, goodwill and fixed asset impairment and deferred tax valuation allowance
	Loss and loss adjustment expenses for the three and nine months ended September 30, 2013 statement of operations included an increase of $143.7 million and $470.5 million, respectively, 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. The Company performed comprehensive updates to its internal reserve study in response to continued observance in the second and third quarters of 2013 of higher than expected reported loss development. In conjunction with its comprehensive internal reviews, the Company also retained a consulting actuary to perform an independent reserve study in the second and third quarters of 2013 covering lines of business comprising over 93% 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 second and third quarter reserve strengthening was viewed by the Company as events or circumstances that required the Company to perform a detailed quantitative analysis of whether its recorded goodwill was impaired. After performing the quantitative analysis in the second quarter of 2013, it was determined that $214.0 million of goodwill, which represents all of the goodwill allocated to the Commercial Insurance reporting unit, was impaired. In the third quarter of 2013, management concluded that the remaining $55.5 million of goodwill, all of which was allocated to the Personal Insurance reporting unit was impaired. In addition, $1.9 million of additional goodwill resulting from the acquisition of marine and energy business in July of 2013 was fully impaired as of September 30, 2013. Additionally, in the third quarter of 2013, the Company impaired $125.8 million of fixed assets. See “Note 5 – Goodwill, Intangible and Fixed Assets Impairments” for additional detail on the goodwill and fixed asset impairments.
	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 development 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, has provided a full valuation allowance against its deferred tax asset at September 30, 2013.
	Reinsurance Agreements
	In the third quarter of 2013, Tower 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 ceded 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 ceded 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 (the “TICNY/Southport Re ADC”). 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 “TRL/Southport Re ADC”, or, collectively, the “Southport Re ADCs”). The agreements have special termination clauses whereby Southport Re 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”. Southport Re has not provided notice to terminate the agreement.
	The reinsurance agreements with Arch, Hannover and Southport Re resulted in ceded premiums earned, ceding commission revenue and ceded loss and loss adjustment expenses of $64.5 million, $16.8 million, and $38.2 million for the three months ended September 30, 2013. A component of these three reinsurance agreements qualifies for retroactive reinsurance accounting treatment. However, since these agreements did not result in an accounting gain, there is no deferred gain recognized to be amortized into the statement of operations in future periods.
	A.M. Best, Fitch and Demotech Downgrade the Company’s Financial Strength and Issuer Credit Ratings
	On December 20, 2013, A.M. Best lowered the financial strength ratings of each of Tower’s insurance subsidiaries from “B++” (Good) to “B” (Fair) (the seventh highest of fifteen rating levels), as well as the issuer credit ratings of each of Tower’s insurance subsidiaries from “bbb” to “bb”. Previously, on October 8, 2013, A.M. Best had downgraded the financial strength rating of each of Tower’s insurance subsidiaries to “B++” (Good) and their respective issuer credit ratings to “bbb” from “a-”. In addition, on December 20, 2013 A.M. Best downgraded the issuer credit rating of TGI as well as the debt rating on its $146.9 million 5.00% senior convertible notes due 2014 (the “Notes”) to “b-” from “bb”. On the same date, A.M. Best also downgraded the financial strength rating of CastlePoint Reinsurance Company, Ltd. (Bermuda) to “B” (Fair) from “B++” (Good) and its issuer credit rating to “bb” from “bbb” and downgraded the issuer credit rating of Tower Group International, Ltd. to “b-” from “bb”. TGI and each of its insurance subsidiaries currently are and will continue to be under review with negative implications pending further discussions between A.M. Best and management. In downgrading Tower’s ratings, A.M. Best stated that its actions “consider the magnitude of the charges taken and the material adverse impact on Tower’s risk-adjusted capitalization, financial leverage, liquidity and coverage ratios,” “consider the reduced financial flexibility [of the Company] given [its] delay in earnings, the decline in shareholder confidence and the corresponding decline in share price” and “reflect the potential for further adverse reserve development, increased competitive challenges and due to the ratings downgrade, potential actions taken by third party reinsurers and lenders.” Following the announcement of the ACP Re merger, on January 10, 2014 A.M. Best maintained the under review status of Tower’s financial strength and issuer credit ratings and revised the implications from “negative” to “developing” for all of these ratings. A.M. Best stated that, “[t]he under review status with developing implications reflects the potential benefits to be garnered from the transaction as well as the potential downside from any additional adverse reserve development and/or any unforeseen events that might transpire up until the close of the transaction…”
	On January 2, 2014, Fitch downgraded Tower’s issuer default rating from “B” to “CC” and the insurer strength ratings of its insurance subsidiaries from “BB” to “B”. On October 7, 2013, Fitch downgraded Tower’s issuer default rating to “B” (the sixth highest of 11 such ratings) from “BBB” and the insurer strength ratings of its insurance subsidiaries to “B” (the fifth highest of Fitch Ratings’ nine such ratings) from “A-”. In downgrading such ratings, Fitch stated that it “is concerned that Tower’s competitive position has been materially damaged, negatively impacting the Company’s financial flexibility and ability to write new business” and that “the magnitude of the second quarter charges was large enough to cause several key ratios to fall well outside of previously established ratings downgrade triggers, which resulted in the multi-notch downgrade.” On January 6, 2014, Fitch revised Tower’s rating watch status to “evolving” from “negative” following the ACP Re merger announcement, and stated that “[t]he Evolving Watch reflects that the ratings could go up if the merger closes; however, ratings could be lowered if the merger does not occur and [the Company] is unsuccessful in addressing upcoming debt maturity or if additional reserve deficiencies develop.”
	On December 24, 2013, Demotech, Inc. (“Demotech”) announced the withdrawal of its Financial Stability Ratings® (FSRs) assigned to the following insurance subsidiaries: Kodiak Insurance Company, Massachusetts Homeland Insurance Company, Tower Insurance Company of New York and York Insurance Company of Maine. Concurrently, Demotech advised that the FSRs assigned to Adirondack Insurance Exchange, Mountain Valley Indemnity Company, New Jersey Skylands Insurance Association and New Jersey Skylands Insurance Company remain under review.
	Previously, on October 7, 2013, Demotech had 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 2013, to result in a significant decrease in the amount of premiums the insurance subsidiaries are able to write. The net written premiums were $237.6 million and $1,093.4 million for the three and nine months ended September 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”).
	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 Reinsurance Company (“CastlePoint Re”), one of its Bermuda based insurance subsidiaries. The 2013 obligations that CastlePoint Re assumes from the U.S. based insurance subsidiaries are then retroceded to Tower Reinsurance, Ltd. (“TRL”), Tower’s other Bermuda based insurance subsidiary. 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. As a result of these transactions, TRL is required to collateralize $243.4 million of assumed reserves in a reinsurance trust for the benefit of TICNY, the lead pool company of the U.S. insurance companies. While TRL had unencumbered liquid assets of $98.6 million at September 30, 2013, and during the fourth quarter of 2013, TRL received unencumbered cash proceeds totaling $80.9 million from two commuted reinsurance treaties, the required reinsurance trust could not be established until approval was received from the BMA. The BMA approved the transfer of assets from TRL to CastlePoint Re, allowing CastlePoint Re to increase the funding in the reinsurance trust for the benefit of TICNY in January 2014. NYDFS has confirmed this will be acceptable for the purpose of admitted surplus and capital on TICNY’s 2013 statutory basis financial statements.
	The Company projects, based on estimated RBC calculations as of September 30, 2013, that two of its U.S. based insurance subsidiaries (which are New York domiciled) may have minimum capital and surplus below Company Action Level and may not meet the minimum capital and surplus requirements of their respective state regulators. As a result, management has discussed the ACP Re Merger Agreement and provided its RBC forecasts to the regulators to document the Company’s business plan to bring these two U.S. based insurance subsidiaries’ capital and surplus levels above Company Action Level.
	The NYDFS has issued orders for seven of Tower’s insurance subsidiaries, subjecting them to heightened regulatory oversight, which includes providing the NYDFS with increased information with respect to the insurance subsidiaries business, operations and financial condition. In addition, the NYDFS has placed limitations on payments and transactions outside the ordinary course of business and material changes in the insurance subsidiaries’ management and related matters.
	The Massachusetts Division of Insurance (“MDOI”) and Tower management have agreed to certain restrictions on the operations of Tower’s two Massachusetts domiciled insurance subsidiaries. Tower management has agreed to cause these subsidiaries to provide the MDOI 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.
	The Maine Bureau of Insurance entered a Corrective Order imposing certain conditions on Maine domestic insurers York Insurance Company of Maine (“YICM”) and North East Insurance Company (“NEIC”). The Corrective Order imposes increased reporting obligations on YICM and NEIC with respect to business operations and financial condition and imposes restrictions on payments or other transfers of assets from YICM and NEIC outside the ordinary course of business.
	As of September 30, 2013, TRL had capital and surplus that did not meet the minimum capital and surplus requirements of the BMA.
	The BMA has issued directives for TRL and CastlePoint Re, subjecting them to heightened regulatory oversight and requiring BMA approval before certain transactions can be executed. Tower has been complying with the directives issued by the BMA.
	Liquidity
	TGI was 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 was outstanding as of September 30, 2013) and is the obligor under the Convertible Senior Notes (“Notes”) due September 2014 ($150 million par outstanding as of September 30, 2013). The indebtedness of TGI is guaranteed by Tower Group International, Ltd. (“TGIL”), and for purposes of the credit facility was also guaranteed by several of TGIL’s non-insurance subsidiaries.
	On December 13, 2013, TGI paid in full the $70.0 million outstanding on the bank credit facility and the bank credit facility has been terminated. The $70.0 million was provided, primarily, from the sale of Tower’s 10.7% ownership in Canopius Group Limited (“Canopius Group”) on December 13, 2013. See “Note 19 - Subsequent Events” for discussion on the sale of TGI’s interest in Canopius Group.
	The Company’s plan to repay the Notes is related to the closing of the ACP Re Merger Agreement with ACP Re. In the event that the ACP Re Merger Agreement does not close, the Company would evaluate a combination of using proceeds from the sale of assets held at TGI, including but not limited to, renewal rights on its commercial and personal lines of business and certain of its insurance companies to pay down the principal of the Notes. The Company can provide no assurance that it will be successful in finalizing the liquidation of the assets held at TGI or selling certain of its operating assets.
	As of September 30, 2013, there were $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.
	The merger with ACP Re is expected to close by the summer of 2014, and there are contractual termination rights available to each of Tower and ACP Re under various circumstances. Therefore, there can be no guarantee that the Company will be able to remedy current statutory capital deficiencies in certain of its 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.
	Other
	Tower received a document request from the U.S. Securities and Exchange Commission (the “SEC”) dated January 13, 2014, as part of an informal inquiry (the “SEC Request”). The SEC Request asks for documents related to Tower’s financial statements, accounting policies, and analysis. Tower is cooperating with the SEC’s inquiry and has provided the requested information.
	The Company and certain of its current and former senior officers have been named as defendants in several class action lawsuits instituted against them by certain shareholders. In addition, the Company and certain of its current and former directors, along with certain other parties, have been named as defendants in a putative class action lawsuit instituted against them by another purported shareholder. See “Note 18 – Contingencies” 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 reflected the way management organized the Company for operating decisions and assessing profitability in the second quarter of 2013, subsequent to the Canopius Merger Transaction.
	In the third quarter of 2013, as a result of the significant business developments affecting the Company in the second and third quarters of 2013, as discussed above, the Company again changed the presentation of its business results by reporting its specialty business with its commercial business in the Commercial Insurance segment, and reporting its international assumed reinsurance business and certain U.S. based assumed reinsurance in a new Assumed Reinsurance segment. No changes were made to the Personal Insurance segment in the third quarter of 2013, and, the Company continues to 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 Canopius Merger Transaction and the significant business developments and risks and uncertainties that occurred in 2013. The prior period segment disclosures have been restated to conform to the current presentation.
	Following the changes in presentation the Company now operates in three business segments: Commercial Insurance, Assumed 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 and through program underwriting agents, on both an admitted and non-admitted basis;
		•	Assumed Reinsurance (“Assumed Reinsurance”) segment offers international assumed reinsurance and certain U.S. based 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.
	Marine and Energy Reinsurance and Renewal Rights Acquisition (the “Marine and Energy Acquisition”)
	On July 8, 2013, Tower entered into a reinsurance contract with ANV Lloyd’s Syndicate 1861 (“ANV 1861”) to assume a portfolio of ANV 1861’s marine and energy policies. Tower assumed $9.0 million of unearned premiums. In addition, Tower also (i) obtained the renewal rights for ANV 1861’s marine and energy business and (ii) hired certain employees from ANV’s underwriting team. This acquisition was accounted for as a business combination. Tower paid fees of $1.5 million, had fair value liabilities of $0.4 million, and recorded goodwill of $1.9 million. As disclosed in “Note 5 – Goodwill and Intangible Assets”, the Company concluded the $1.9 million was impaired as of September 30, 2013.
	Resignation of Tower’s Chairman of the Board, President and Chief Executive Officer
	On February 7, 2014, Tower announced that its Chairman of the Board of Directors (the “Board”), President and Chief Executive Officer, Michael H. Lee, resigned, effective immediately, from the Company and the Company’s Board to pursue personal and other career opportunities. In connection with his resignation, Mr. Lee will receive a severance payment calculated pursuant to terms of his employment agreement.
	Tower also announced that Jan R. Van Gorder, who is the lead independent director of the Board and a member of the Board’s Audit Committee, Compensation Committee and Corporate Governance and Nominating Committee, would be appointed to succeed Mr. Lee as Chairman of the Board, and William W. Fox, Jr., who had served as a member of the Board and of the Board’s Audit Committee and Corporate Governance and Nominating Committee until his resignation from the Board on December 31, 2013, will succeed Mr. Lee as President and Chief Executive Officer of Tower immediately after the filing of the September 30, 2013 Form 10-Q. Following Mr. Lee’s resignation and prior to the filing of the September 30, 2013 Form 10-Q, William E. Hitselberger is the person performing functions of or similar to that of President and Chief Executive Officer of Tower. Mr. Fox’s employment terms were approved by the Board of Directors on February 9, 2014. On February 9, 2014, the Board of Directors appointed Mr. Van Gorder as Chairman of the Board.

Restatement_of_previously_issu

Restatement of previously issued financial statements	9 Months Ended
	Sep. 30, 2013
Restatement of previously issued financial statements	'
	Note 2—Restatement of previously issued financial statements
	On November 26, 2013, the Company filed Amendment No. 2 to Tower’s Annual Report on Form 10-K for the year ended December 31, 2012 to restate its audited annual consolidated financial statements as of and for the years ended December 31, 2011 and 2012 and to revise its audited annual consolidated financial statements for the year ended December 31, 2010. In addition, on November 26, 2013, the Company also filed Amendment No. 1 to its Quarterly Report on Form 10-Q for the quarter ended March 31, 2013 to revise its unaudited interim consolidated financial statements as of and for the three months ended March 31, 2013 and 2012.
	On November 7, 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 that previously issued financial statements of the Company covering one or more periods needed to be revised or restated and could 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 needed 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 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 $7.2 million for the years ended December 31, 2012, 2011, 2010 and 2009, respectively. The Company has also corrected other immaterial adjustments that were initially recorded in the period they were identified.
	The effects of the restatement on the consolidated balance sheets are presented in the table below:
		As of December 31, 2012
	($ in thousands, except par value and share amounts)	As			Restated			Effect of
		Previously						Adjustments
		Filed
	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	)
	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	9 Months Ended
	Sep. 30, 2013
Accounting Policies and Basis of Presentation	'
	Note 3—Accounting Policies and Basis of Presentation
	Basis of Presentation
	The Canopius 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 Canopius 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 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 the Company’s consolidated financial statements as of and for the year ended December 31, 2012 and notes thereto included in the Company’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 nine months ended September 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 $1.8 million. Since this was a non-recurring transaction between entities under common control, assets were transferred at historical book value. The difference in the consideration paid and the book value of the assets transferred was treated as an adjustment to equity. This transaction had no effect on consolidated shareholders’ equity.
	Reclassifications and Adjustments
	Since the Company accounted for the Canopius Merger Transaction as a reverse acquisition and recapitalization, it has retroactively restated Common Stock, Treasury Stock and Paid-in-Capital accounts and earnings per share for periods prior to the Canopius Merger Transaction to reflect the historical capitalization of TGI, adjusted for the 1.1330 conversion ratio as discussed in “Note 4 –Canopius Merger Transaction”. Certain other reclassifications have also been made to prior years’ financial information to conform to the current year presentation, including the changes in segment presentation discussed in “Note 1 – Nature of Business.”
	The table below reflects the previously reported and revised shareholders’ equity accounts resulting from the Canopius Merger Transaction:
	($ in thousands, except per share amounts)	As previously			Revised
		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 September 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.56		$	0.5
	Diluted		0.56			0.5
	Weighted average common shares outstanding
	Basic		38,371			42,449
	Diluted		38,395			42,476
	For the nine-months ended September 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.62		$	0.54
	Diluted		0.62			0.54
	Weighted average common shares outstanding
	Basic		38,929			43,045
	Diluted		38,979			43,130
	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 has considered this guidance in connection with its impairment testing of its indefinite-lived intangible assets. 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.
	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.

Canopius_Merger_Transaction

Canopius Merger Transaction

9 Months Ended

Sep. 30, 2013

Canopius Merger Transaction

'

Note 4—Canopius Merger Transaction

On August 20, 2012, TGI closed on its previously announced $74.9 million acquisition of a 10.7% stake in Canopius Group. 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 Canopius 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 of $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 Canopius 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 Canopius 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 were 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 Canopius 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 Canopius 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 Canopius Merger Transaction.

The Canopius Merger Transaction was 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 provided the Company with an international platform through which it accesses the U.S., Bermuda and the Lloyd’s of London (“Lloyd’s”) markets.

On December 13, 2013, Tower sold its 10.7% ownership in Canopius Group Limited. See “Note 19 - Subsequent Events” for discussion on the sale of TGI’s interest in Canopius Group.

Accounting for the Canopius Merger Transaction

The Company has accounted for the Canopius 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 Canopius Merger Transaction was primarily based on the fact that immediately following the close of the Canopius 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 Canopius 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 Canopius 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 Canopius 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 Canopius Merger Transaction, TGI entered into a commutation agreement whereby 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 Canopius Merger Transaction on March 13, 2013.

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 nine months ended September 30, 2013, the Company recognized approximately $20.3 million of such costs, all of which have been classified within “acquisition-related transaction costs” on the consolidated statement of operations. Such costs included $11.6 million in compensation expense (of which accelerated vesting of restricted stock was $10.3 million) and $8.7 million in legal and accounting fees.

The resulting goodwill recognized in connection with the Canopius Merger Transaction was mainly derived from the synergies and economies of scale expected to result from the combined operations of the Company. This goodwill was fully impaired in the second quarter of 2013. See “Note 5 – Goodwill and Intangible Assets” for the allocation of the Canopius Merger Transaction goodwill by segment and discussion on the non-cash impairment charge.

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. The risk premium was fully amortized in the third quarter of 2013 in connection with the September 30, 2013 commutation and novation of the Syndicate 4444 YOA 2012 and YOA 2011 and prior years assumed reinsurance and retrocession agreements.

The September 30, 2013 commutation of the Syndicate 4444 YOA 2012 and YOA 2011 and prior years retrocession agreements with CRL and the novation of the assumed reinsurance with Canopius Group on these same contracts had the following effects on the consolidated financial statements in the third quarter of 2013, excluding the $19.1 million of reserves for risk premium noted above:

•

Reinsurance recoverables, prepaid reinsurance and funds held by reinsurance for amounts due from CRL were zero as of September 30, 2013. These amounts were $446.8 million, $30.1 million, and $721.9 million as of June 30, 2013;

•

Loss and loss adjustment expense liabilities, unearned premiums, and funds held under reinsurance agreements for amounts due to Canopius Group were zero as of September 30, 2013. These amounts were $581.5 million, $38.1 million and $576.3 million as of June 30, 2013;

•

$30.3 million of assets held as “Funds at Lloyds” became unencumbered; and

•

No commutation gain or loss was recognized on these transactions.

Since the effective date of the Canopius Merger Transaction on March 13, 2013 through September 30, 2013, the operations of the acquired business accounted for approximately $96.9 million and $(3.5) 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 three and nine months ended September 30, 2013 and 2012, as if the Canopius 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

Nine Months Ended

September 30,

September 30,

($ in thousands)

2013

2012

2013

2012

Revenues

$

442,902

$

522,984

$

1,383,047

$

1,502,017

Net Income (Loss)

(344,132

)

42,333

(829,380

)

52,407

Goodwill_Intangible_Fixed_Asse

Goodwill, Intangible Fixed Asset Impairments	9 Months Ended
	Sep. 30, 2013
Goodwill, Intangible Fixed Asset Impairments	'
	Note 5—Goodwill, Intangible Fixed Asset Impairments
	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 Canopius Merger Transaction (See “Note 4 – Canopius 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 Canopius Merger Transaction to the Commercial Insurance reporting unit.
	2013 Reorganizations
	In the second quarter of 2013, the Company changed the way it presented its results by segment. Following the reorganization, based on information 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 Assumed Reinsurance and (iii) Personal Insurance. (Each of the reporting units corresponds with the Company’s reporting segments).
	In the third quarter of 2013, the Company re-evaluated the way it presents its results by segment, as described in “Note 1 – Nature of Business”. Following the third quarter 2013 reorganization, based on the information 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) Assumed Reinsurance and (iii) Personal Insurance. (Each of the reporting units corresponds with the Company’s reporting segments).
	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 1 of 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 a quarterly impairment test was required as a result of the reorganization and significant prior years’ loss reserves incurred (see “Note 9 – Loss and Loss Adjustment Expense”). In the third quarter of 2013, as a result of the additional significant prior years’ loss reserves incurred, management concluded a quarterly impairment test was required again as of September 30, 2013 in the preparation of the September 30, 2013 consolidated financial statements.
	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. As of June 30, 2013, the Company reported $55.5 million of goodwill, all of which related to the Personal Insurance reporting unit.
	In conducting the goodwill impairment analysis for the quarter ended September 30, 2013, the Company estimated the Personal Insurance fair values using Tower’s current market capitalization, adjusted for a control premium. Historically, the Company also utilized various market multiple approaches for Personal Insurance reporting unit. However, based upon the significant 2013 events, including A.M. Best’s downgrade to “B” for the insurance subsidiaries, management in its judgment concluded the market capitalization, adjusted for a control premium, was most indicative of a price a market participant would pay for the reporting unit.
	Step 1 of the impairment test as of September 30, 2013 indicated the Personal Insurance unit’s carrying value exceeded its fair value.
	Accordingly, the Company performed a Step 2 impairment test on the Personal Insurance reporting unit. Based on the results, the Company recorded a non-cash goodwill impairment charge of $55.5 million to write-down all of the goodwill in the Personal Insurance reporting unit as of September 30, 2013. As of September 30, 2013, the Company had no goodwill reported on its consolidated balance sheet.
	Marine and Energy Acquisition goodwill
	In the third quarter of 2013, the Company accounted for the Marine and Energy Acquisition as a business combination and recorded $1.9 million of goodwill in the Commercial Insurance reporting unit. As of September 30, 2013, in response to the significant business developments discussed in “Note 1 – Nature of Business,” management concluded this goodwill was fully impaired.
	The following table reflects the changes to goodwill during 2013 and is presented using the reporting units prior to the reorganizations.
	($ in thousands)	Commercial			Personal			Total
		Insurance			Insurance
	Balance, January 1, 2013	$	185,918		$	55,540		$	241,458
	Goodwill from Canopius Merger Transaction		28,131			-			28,131
	Good will from Marine and Energy Acquisition		1,853			-			1,853
	Goodwill impairment		(215,902	)		(55,540	)		(271,442	)
	Total, September 30, 2013	$	-		$	-		$	-
	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 in the second quarter of 2013, and concluded an impairment charge of $3.8 million was required to reduce its customer relationship intangible assets. These charges are reported in Other Operating Expenses in the consolidated statements of operations. In addition, after further reserve strengthening and A.M. Best rating downgrades in the third quarter of 2013, management concluded an impairment charge of another $18.1 million was required to further reduce the customer relationship intangible asset.
	As of September 30, 2013, after impairment charges, the Company has $5.0 million of customer relationships recorded as intangible assets. Subsequent intangible asset assessments could result in impairment due to future unfavorable developments, including rating agency downgrades, significant declines in renewal retention rates or increases in expected loss ratios.
	Fixed Assets
	Furniture, leasehold improvements, computer equipment, and software, including internally developed software, are reported at cost less accumulated depreciation and amortization. As of December 31, 2012, gross fixed assets and capital leases were $194.0 million and accumulated depreciation was $54.7 million (for net fixed assets and capital leases of $139.3 million).
	As a result of the Significant Business Developments and Risks and Uncertainties discussed in “Note 1—Nature of Business”, including the A.M. Best, Fitch and Demotech rating downgrades in December of 2013 and the expected significant declines in net written premiums and the orders and restrictions placed by various insurance departments, management tested fixed assets for recoverability.
	Long-lived tangible and intangible assets that an entity will continue to hold and use should be reviewed for impairment, which includes two steps. The first step in the impairment test is to determine whether the long-lived assets are recoverable as measured by comparing net carrying value of the asset or asset group to the undiscounted net cash flows to be generated from the use and eventual disposition of that asset or asset group. In performing this step, management concluded that the sum of the undiscounted cash flows was less than the carrying value of the asset group. Accordingly, the Company performed an impairment analysis in which the implied fair value of the fixed assets was determined to be lower than the carrying value.
	Management determined the fair value of fixed assets by (i) calculating an estimated software charge (i.e. fee for use of software) a market participant would pay the owner of the asset in return for the ability to use the Company’s software and (ii) performing an orderly liquidation value analysis ranging from 0%-15% for furniture, leasehold improvements and computer equipment, and concluded the fixed assets were impaired as of September 30, 2013. The Company recorded a non-cash charge to earnings of $125.8 million in the third quarter of 2013. This charge is recorded within Goodwill and fixed-assets impairment in the statement of operations. As of September 30, 2013, the Company has recorded $20.7 million of fixed assets in Other Assets on the consolidated balance sheet.

Variable_Interest_Entities_VIE

Variable Interest Entities ("VIEs")	9 Months Ended
	Sep. 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 September 30, 2013, the Reciprocal Exchanges recognized total revenues, total expenses and net income (loss) of $47.1 million, $43.6 million and $3.5 million, respectively. For the three months ended September 30, 2012, the Reciprocal Exchanges recognized total revenues, total expenses and net income of $50.2 million, $45.9 million and $4.3 million, respectively.
	For the nine months ended September 30, 2013, the Reciprocal Exchanges recognized total revenues, total expenses and net income (loss) of $143.5 million, $150.5 million and $ (7.0) million, respectively. For the nine months ended September 30, 2012, the Reciprocal Exchanges recognized total revenues, total expenses and net income of $149.6 million, $141.8 million and $7.8 million, respectively.

Investments

Investments	9 Months Ended
	Sep. 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 September 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)
	September 30, 2013
	U.S. Treasury securities		$	395,876		$	1,245		$	(4,017	)	$	393,104		$	-
	U.S. Agency securities			100,417			1,962			(112	)		102,267			-
	Municipal bonds			311,386			9,303			(6,187	)		314,502			-
	Corporate and other bonds
	Finance			201,533			11,512			(3,163	)		209,882			-
	Industrial			394,777			11,786			(4,435	)		402,128			-
	Utilities			45,111			1,501			(1,698	)		44,914			-
	Commercial mortgage-backed securities			215,545			20,066			(1,893	)		233,718			(570	)
	Residential mortgage-backed securities
	Agency backed securities			77,746			1,893			(455	)		79,184			-
	Non-agency backed securities			33,247			4,116			(40	)		37,323			(22	)
	Asset-backed securities			56,326			834			(49	)		57,111			-
	Total fixed-maturity securities			1,831,964			64,218			(22,049	)		1,874,133			(592	)
	Preferred stocks, principally financial sector			21,331			43			(2,392	)		18,982			-
	Common stocks, principally financial and industrial sectors			82,327			9,942			(3,344	)		88,925			-
	Short-term investments			5,925			-			(36	)		5,889			-
	Total, September 30, 2013		$	1,941,547		$	74,203		$	(27,821	)	$	1,987,929		$	(592	)
	Tower		$	1,692,456		$	66,082		$	(22,954	)	$	1,735,584		$	(592	)
	Reciprocal Exchanges			249,091			8,121			(4,867	)		252,345			-
	Total, September 30, 2013		$	1,941,547		$	74,203		$	(27,821	)	$	1,987,929		$	(592	)
	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 $ 48.7 million of cash and cash equivalents as of September 30, 2013. In addition, the Company had $ 467.8 million and $311.3 million of cash and cash equivalents and investments as of September 30, 2013 and December 31, 2012, respectively, held by counterparties as collateral or in trusts to support letters of credit issued on the Company’s behalf, reinsurance liabilities on certain assumed reinsurance treaties, collateral posted for certain leases and other purposes.
	The Company also deposits funds with various state and governmental authorities in the U.S. For a discussion of the Company’s deposits with state and governmental authorities, see “Note 7– Investments” of the Notes to Consolidated Financial Statements in the Company’s Amendment No. 2 to its Annual Report on Form 10-K for the year ended December 31, 2012.
	Major categories of net investment income are summarized as follows:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Income
	Fixed-maturity securities		$	19,190		$	24,217		$	60,725		$	74,141
	Equity securities			3,615			7,856			16,907			22,095
	Cash and cash equivalents			511			379			581			1,118
	Other invested assets			4,329			786			10,743			3,932
	Other			36			(258	)		651			150
	Total			27,681			32,980			89,607			101,436
	Expenses
	Investment expenses			(2,049	)		(1,591	)		(5,256	)		(4,323	)
Net investment income		$	25,632		$	31,389		$	84,351		$	97,113
Tower			24,899			29,923			82,094			92,448
Reciprocal Exchanges			2,418			3,142			7,257			9,668
Elimination of interest on Reciprocal Exchange surplus notes			(1,685	)		(1,676	)		(5,000	)		(5,003	)
Net investment income		$	25,632		$	31,389		$	84,351		$	97,113
Proceeds from the sale of fixed-maturity securities were $1.3 billion and $1.3 billion for the nine months ended September 30, 2013 and 2012, respectively. Proceeds from the sale of equity securities were $ 970.8 million and $1,149.5 million for the nine months ended September 30, 2013 and 2012, respectively.
Gross realized gains, losses and impairment write-downs on investments are summarized as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
($ in thousands)		2013			2012			2013			2012
Fixed-maturity securities
Gross realized gains		$	22,687		$	5,594		$	40,530		$	30,756
Gross realized losses			(5,762	)		(271	)		(7,624	)		(2,822	)
			16,925			5,323			32,906			27,934
Equity securities
Gross realized gains			3,131			5,109			12,690			9,288
Gross realized losses			(3,458	)		(6,890	)		(20,988	)		(23,050	)
			(327	)		(1,781	)		(8,298	)		(13,762	)
Other
Gross realized gains			8,212			726			12,067			2,516
Gross realized losses			(2,490	)		(1,396	)		(4,393	)		(5,509	)
			5,722			(670	)		7,674			(2,993	)
Net realized gains (losses) on investments			22,320			2,872			32,282			11,179
Other-than-temporary impairment losses:
Fixed-maturity securities			(2,630	)		(438	)		(2,817	)		(1,320	)
Equity securities			(1,562	)		(1,289	)		(6,520	)		(5,367	)
Total other-than-temporary impairment losses recognized in earnings			(4,192	)		(1,727	)		(9,337	)		(6,687	)
Total net realized investment gains (losses)		$	18,128		$	1,145		$	22,945		$	4,492
Tower		$	17,093		$	80		$	21,083		$	1,108
Reciprocal Exchanges			1,035			1,065			1,862			3,384
Total net realized investment gains (losses)		$	18,128		$	1,145		$	22,945		$	4,492
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 nine months ended September 30, 2013 and 2012:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
($ in thousands)		2013			2012			2013			2012
U.S. Treasury securities		$	(801	)	$	-		$	(801	)	$	-
U.S. Agency securities			(571	)		-			(571	)		-
Municipal bonds			(367	)		(113	)		(367	)		(113	)
Corporate and other bonds			(596	)		(292	)		(596	)		(1,029	)
Commercial mortgage-backed securities			(361	)		(27	)		(408	)		(430	)
Residential mortgage-backed securities			(269	)		(6	)		(409	)		(34	)
Equities			(1,562	)		(1,289	)		(6,520	)		(5,367	)
Other-than-temporary-impairments			(4,527	)		(1,727	)		(9,672	)		(6,973	)
Portion of loss recognized in accumulated other comprehensive income (loss)			335			-			335			286
Impairment losses recognized in earnings		$	(4,192	)	$	(1,727	)	$	(9,337	)	$	(6,687	)
Tower		$	(4,191	)	$	(1,727	)	$	(9,336	)	$	(6,687	)
Reciprocal Exchanges			(1	)		-			(1	)		-
Impairment losses recognized in earnings		$	(4,192	)	$	(1,727	)	$	(9,337	)	$	(6,687	)
The following table provides a rollforward of the cumulative amounts of credit OTTI for securities held as of September 30, 2013 and 2012 showing the amounts that have been included in earnings on a pretax basis for the three months ended September 30, 2013 and 2012:
		Three Months Ended
		September 30,
($ in thousands)		2013			2012
Balance, July 1,		$	4,539		$	6,119
Additional credit losses recognized during the period, related to securities for which:
No OTTI has been previously recognized			2,220			405
OTTI has been previously recognized			410			33
Reductions due to:
Securities sold during the period (realized)			(1,925	)		(1,475	)
Balance, September 30,		$	5,244		$	5,082
The following table provides a rollforward of the cumulative amounts of credit OTTI for securities held as of September 30, 2013 and 2012 showing the amounts that have been included in earnings on a pretax basis for the nine months ended September 30, 2013 and 2012:
		Nine Months Ended
		September 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			2,407			1,259
OTTI has been previously recognized			410			61
Reductions due to:
Securities sold during the period (realized)			(2,065	)		(8,904	)
Balance, September 30,		$	5,244		$	5,082
Unrealized Losses
There are 573 securities at September 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 September 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 $22.0 million as of September 30, 2013, consisting primarily of municipal bonds, corporate and other bonds and U.S. Treasury securities of $19.5 million. The total fixed-maturity portfolio of gross unrealized losses included 556 securities which were, in aggregate, approximately 2.8% below amortized cost. Of the 556 fixed maturity investments identified, 44 have been in an unrealized loss position for more than 12 months. The total unrealized loss on these investments at September 30, 2013 was $0.17 million. Management does not consider these investments to be other-than-temporarily impaired.
For common stocks, there were 11 securities in a loss position at September 30, 2013 totaling $3.3 million. Management evaluated the financial condition of the common stock issuers, the severity and duration of the impairment, and the Company’s ability and intent to hold to recovery. The evaluation consisted of a detailed review, including but not limited to some or all of the following factors for each security: the current S&P rating, analysts’ reports, past earnings trends and analysts’ earnings expectations for the next 12 months, liquidity, near-term financing risk, and whether the company was currently paying dividends on its equity securities. Management does not consider these investments to be other-than-temporarily impaired.
The following table presents information regarding invested assets that were in an unrealized loss position at September 30, 2013 and December 31, 2012 by amount of time in a continuous unrealized loss position:
		Less than 12 Months						12 Months or Longer						Total
($ in thousands)		Fair			Unrealized			Fair			Unrealized			Aggregate			Unrealized
		Value			Losses			Value			Losses			Fair Value			Losses
September 30, 2013
U.S. Treasury securities		$	289,315		$	(4,017	)	$	-		$	-		$	289,315		$	(4,017	)
U.S. Agency securities			32,082			(112	)		-			-			32,082			(112	)
Municipal bonds			107,253			(6,187	)		-			-			107,253			(6,187	)
Corporate and other bonds
Finance			59,845			(3,163	)		-			-			59,845			(3,163	)
Industrial			139,971			(4,277	)		3,700			(158	)		143,671			(4,435	)
Utilities			31,361			(1,698	)		-			-			31,361			(1,698	)
Commercial mortgage-backed securities			52,586			(1,893	)		-			-			52,586			(1,893	)
Residential mortgage-backed securities
Agency backed			21,729			(454	)		206			(1	)		21,935			(455	)
Non-agency backed			1,178			(27	)		183			(13	)		1,361			(40	)
Asset-backed securities			12,407			(49	)		-			-			12,407			(49	)
Total fixed-maturity securities			747,727			(21,877	)		4,089			(172	)		751,816			(22,049	)
Preferred stocks			10,694			(2,148	)		6,161			(244	)		16,855			(2,392	)
Common stocks			33,334			(3,344	)		-			-			33,334			(3,344	)
Short-term investments			3,889			(36	)		-			-			3,889			(36	)
Total, September 30, 2013		$	795,644		$	(27,405	)	$	10,250		$	(416	)	$	805,894		$	(27,821	)
Tower		$	692,839		$	(22,572	)	$	9,697		$	(382	)	$	702,536		$	(22,954	)
Reciprocal Exchanges			102,805			(4,833	)		553			(34	)		103,358			(4,867	)
Total, September 30, 2013		$	795,644		$	(27,405	)	$	10,250		$	(416	)	$	805,894		$	(27,821	)
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 September 30, 2013 and December 31, 2012:
		Tower						Reciprocal Exchanges						Total
($ in thousands)		Amortized			Fair Value			Amortized			Fair Value			Amortized			Fair Value
		Cost						Cost						Cost
September 30, 2013
Remaining Time to Maturity
Less than one year		$	33,359		$	34,019		$	4,007		$	4,123		$	37,366		$	38,142
One to five years			574,233			586,305			45,325			47,333			619,558			633,638
Five to ten years			525,982			529,361			75,673			75,226			601,655			604,587
More than 10 years			148,759			150,094			41,762			40,335			190,521			190,429
Mortgage and asset-backed securities			303,291			324,533			79,573			82,804			382,864			407,337
Total, September 30, 2013		$	1,585,624		$	1,624,312		$	246,340		$	249,821		$	1,831,964		$	1,874,133
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 September 30, 2013 and December 31, 2012:
($ in thousands)		September 30,			December 31,
		2013			2012
Limited partnerships, equity method		$	40,936		$	23,864
Real estate, amortized cost			5,882			7,422
Securities reported under the fair value option			42,541			25,000
Other			8,200			1,500
Total		$	97,559		$	57,786
Securities reported under the fair value option include seven 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 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 September 30, 2013, the Company and its insurance companies had future funding commitments of $51.0 million including but not limited to the limited partnerships.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 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 September 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
	September 30, 2013
	Fixed-maturity securities
	U.S. Treasury securities	$	-	$	393,104		$	-	$	393,104
	U.S. Agency securities		-		102,267			-		102,267
	Municipal bonds		-		314,502			-		314,502
	Corporate and other bonds		-		656,924			-		656,924
	Commercial mortgage-backed securities		-		233,718			-		233,718
	Residential mortgage-backed securities
	Agency		-		79,184			-		79,184
	Non-agency		-		37,323			-		37,323
	Asset-backed securities		-		57,111			-		57,111
	Total fixed-maturities		-		1,874,133			-		1,874,133
	Equity securities		107,907		-			-		107,907
	Short-term investments		-		5,889			-		5,889
	Total investments at fair value		107,907		1,880,022			-		1,987,929
	Other invested assets (1)		-		-			42,542		42,542
	Other liabilities									-
	Interest rate swap contracts		-		(6,659	)		-		(6,659	)
	Debt and equity securities sold, not yet purchased		-		(21,486	)		-		(21,486	)
	Total, September 30, 2013	$	107,907	$	1,851,877		$	42,542	$	2,002,326
	Tower	$	105,383	$	1,602,056		$	42,542	$	1,749,981
	Reciprocal Exchanges		2,524		249,821			-		252,345
	Total, September 30, 2013	$	107,907	$	1,851,877		$	42,542	$	2,002,326
	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) $42.5 million of the $97.6 million Other invested assets reported on the consolidated balance sheet at September 30, 2013 is reported at fair value. The remaining $55.1 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 September 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 September 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 losses of $1.1 million and $0.3 million for the three and nine months ended September 30, 2013, respectively.
The Company holds seven 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. Two of the seven securities, START VII CLO and HONDIUS CRAFT CLO, are credit linked notes which will mature in 2015 and 2017, respectively, 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, Aeolus CHIAT SAC, 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 four 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 of the four preferred equity interest investments closed in the latter part of June 2013 (and the fourth investment closed on July 1, 2013), and were therefore carried at their original cost as of June 30, 2013. These four preferred equity interest investments are carried at fair value and are modeled quarterly using discounted market yields from similar hotel properties.
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 September 30, 2013 and 2012 for Tower (the Reciprocal Exchanges have no Level 3 assets):
			Three Months Ended
			September 30,
($ in thousands)			2013			2012
Beginning balance, July 1,		$		30,250		$	24,914
Total gains (losses)-realized / unrealized
Included in net income				-			86
Included in other comprehensive income (loss)				-			-
Purchases, issuances and settlements				12,292			-
Net transfers into (out of) Level 3				-			-
Ending balance, September 30,	$			42,542		$	25,000
The following table summarizes the changes in Level 3 assets measured at fair value for the nine months ended September 30, 2013 and 2012 for Tower (the Reciprocal Exchanges have no Level 3 assets):
			Nine Months Ended
			September 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				17,542			-
Net transfers into (out of) Level 3				-			-
Ending balance, September 30,	$			42,542		$	25,000

Loss_and_Loss_Adjustment_Expen

Loss and Loss Adjustment Expense	9 Months Ended
	Sep. 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 nine months ended September 30, 2013 and 2012:
		Nine Months Ended September 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			-			-			-
	Reduction in net reserves for ADC (i)		(324,109	)		-			(324,109	)		-			-			-
	Incurred related to:
	Current year		669,830			79,989			749,819			723,642			78,763			802,405
	Prior years unfavorable/(favorable) development		470,510			(927	)		469,583			78,231			(7,272	)		70,959
	Total incurred		1,140,340			79,062			1,219,402			801,873			71,491			873,364
	Paid related to:
	Current year		387,636			53,379			441,015			250,062			56,440			306,502
	Prior years		529,371			19,297			548,668			462,134			36,137			498,271
	Total paid		917,007			72,676			989,683			712,196			92,577			804,773
	Net balance at end of period		1,413,930			89,788			1,503,718			1,304,548			103,935			1,408,483
	Add reinsurance recoverables on unpaid losses		572,611			22,152			594,763			294,488			19,138			313,626
	Balance at September 30,	$	1,986,541		$	111,940		$	2,098,481		$	1,599,036		$	123,073		$	1,722,109
	(i) In the third quarter of 2013, Tower executed the Southport Re ADCs (see “Note 1 - Nature of the Business” for further description). The Southport Re ADCs resulted in a direct reduction to net loss reserves.
	The consolidated net loss ratio, which includes the Reciprocal Exchanges, was 104.2% and 59.5% for the three months ended September 30, 2013 and 2012, respectively. Excluding the Reciprocal Exchanges, the net loss ratio was 110.2% and 60.8% for the three months ended September 30, 2013, and 2012, respectively.
	The consolidated net loss ratio, which includes the Reciprocal Exchanges, was 100.9% and 66.6% for the nine months ended September 30, 2013 and 2012, respectively. Excluding the Reciprocal Exchanges, the net loss ratio was 105.0% and 67.7% for the nine months ended September 30, 2013 and 2012, respectively.
	Incurred losses and LAE for the nine months ended September 30, 2013 attributable to events of prior years were $469.6 million including the Reciprocal Exchanges and $470.5 million excluding the Reciprocal Exchanges. Excluding the Reciprocal Exchanges, $483.6 million of the 2013 period reported loss was associated with development associated with Commercial, partially offset by $4.7 million of favorable development in Assumed Reinsurance and $8.4 million of favorable development in Personal segment. 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 a small amount of favorable loss development from more recent years within the short tail property lines of business. Consistent with the second quarter of 2013, the Company continued to experience higher than expected reported loss development during the third quarter of 2013. Additionally, consistent with the second quarter of 2013, 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 93% 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 nine months of 2013 was $209.1 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 ultimate losses for the casualty lines of business. As a result of changes in the underlying actuarial assumptions, estimated ultimate losses for casualty lines of business increased by an additional $279.4 million on a net basis. The increase in estimated ultimate losses for the casualty lines of business was offset by a $17.9 million decrease in estimated ultimate losses within the short-tail property lines of business.
	For the nine months ended September 30, 2013, by line of business, ultimate loss estimates for prior accident years have increased by $174.4 million for workers’ compensation, $127.5 million for commercial package liability, $104.6 million for commercial auto liability and $82.0 million for Other Liability.
	Incurred losses and LAE for the nine months ended September 30, 2012 attributable to events of prior years were $71.0 million. Excluding the Reciprocal Exchanges, the incurred losses and LAE from prior accident years were $78.2 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 $77.0 million within Commercial and $4.0 million within the Personal Insurance segment. This was offset by a decrease of $2.7 million within the Assumed Reinsurance segment. 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 September 30, 2013 and December 31, 2012 are $9.3 million and $8.4 million, respectively, of tabular and non-tabular reserve discount for workers’ compensation and excess workers’ compensation claims.
	As of September 30, 2013 the Company had no risk premiums recorded. The Company amortized all of the $19.1 million of reserve for risk premium recorded in the first quarter of 2013 resulting from the Canopius Merger Transaction. 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, 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 December 31, 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	9 Months Ended
	Sep. 30, 2013
Shareholders' Equity	'
	Note 10—Shareholders’ Equity
	Shares of Common Stock Issued
	As previously discussed in “Note 4 – Canopius Merger Transaction”, the Canopius Merger Transaction was accounted for as a reverse acquisition with TGI treated as the accounting acquirer. Accordingly, Tower’s historical common stock balance immediately prior to the Merger is the historical common stock balance of TGI adjusted for the number of shares issued in the Canopius Merger Transaction by the Company to TGI shareholders (i.e., TGI’s outstanding shares immediately prior to the Canopius 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 Canopius Merger Transaction.
	For the three and nine months ended September 30, 2013, zero and 2,674 new common shares, respectively, were issued as the result of employee stock option exercises. For the three and nine months ended September 30, 2013, zero and 242,626 new common shares, respectively, were issued after the Canopius Merger Transaction as the result of the Company’s restricted stock grants. For the three and nine months ended September 30, 2012, no new common shares were issued as the result of employee stock option exercises. For the three and nine months ended September 30, 2012, 13,292 and 377,187 new common shares, respectively (adjusted for the 1.1330 conversion ratio), were issued as the result of restricted stock grants.
	For the three and nine months ended September 30, 2013, 269 and 341,867 shares, respectively, of common stock were purchased from employees in connection with the vesting of restricted stock issued under the 2008 LTEP (as defined below). For the three and nine months ended September 30, 2012, 6,917 and 117,221 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 2008 LTEP. The shares were withheld at the direction of employees as permitted under the 2008 LTEP 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 nine months ended September 30, 2013, 1,587 and 15,602 shares, respectively, of common stock were surrendered as a result of restricted stock forfeitures. For the three and nine months ended September 30, 2012, 6,654 and 16,528 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 Canopius Merger Transaction, all Treasury shares held by TGI as of the effective date of the Canopius Merger Transaction were cancelled. There were 9,914 Treasury shares of the Company held at September 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 nine months ended September 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 $7.2 million for the three months ended September 30, 2013 and 2012, respectively, were declared and paid. Dividends on common stock and participating unvested restricted stock of $26.2 million and $21.9 million for the nine months ended September 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 Canopius Merger Transaction.
	On November 14, 2013, the Company announced that its Board of Directors determined that it would not declare and pay a dividend to shareholders in the fourth quarter of 2013. There can be no assurance that we will resume paying dividends in the future even if the necessary financial conditions are met and if sufficient cash is available for distribution.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 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 nine months ended September 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		(70,597	)		(1,026	)		78		(71,545	)
	Amounts reclassified from accumulated other comprehensive income, net of tax		(21,418	)		2,522			-		(18,896	)
	Net current period other comprehensive income		(92,015	)		1,496			78		(90,441	)
	Balance at September 30, 2013	$	(4,603	)	$	(4,364	)	$	1,282	$	(7,685	)
	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 nine months ended September 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	$	(21,418	)	Other net realized investment gains
			-		Income tax expense
		$	(21,418	)	Total net of income taxes
	Gains (losses) on cash flow hedges interest rate swaps	$	2,522		Interest expense
			-		Income tax expense
		$	2,522		Total net of income taxes

Debt

Debt	9 Months Ended
	Sep. 30, 2013
Debt	'
	Note 12—Debt
	The Company’s borrowings consisted of the following at September 30, 2013 and December 31, 2012:
		September 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		146,933			126,750			144,673		152,063
	Subordinated debentures		235,058			163,203			235,058		232,678
	Total	$	451,991		$	359,953		$	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 $8.0 million and $8.2 million for the three months ended September 30, 2013 and 2012, respectively. Total interest expense incurred, including interest expense on the funds held liabilities, was $23.5 million and $24.7 million for the nine months ended September 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 September 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 September 30, 2013 and December 31, 2012, the Swaps had a fair value of $6.7 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 nine months ended September 30, 2013 and 2012, $2.5 million and $1.3 million, respectively, were reclassified from AOCI to interest expense for the effects of the hedges. As of September 30, 2013, the Company had collateral on deposit with the counterparty amounting to $6.5 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 Canopius 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 Canopius Merger Transaction. The maturity date and borrowing fees were not changed in this amendment.
	The credit facility contained 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 provided 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) was able to 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. Tower was in compliance with all covenants contained in the credit facility as of September 30, 2013.
	The Company had $70.0 million outstanding as of both September 30, 2013 and December 31, 2012. The weighted average interest rate on the amount outstanding as of September 30, 2013 was 1.94%.
	On December 13, 2013, TGI paid in full the $70.0 million outstanding on the bank credit facility and the bank credit facility has been terminated.
	Convertible Senior Notes
	In September 2010, TGI 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 TGI’s option, at any time on or after March 15, 2014 or earlier under certain circumstances determined by: (i) the market price of TGI’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 Canopius Merger Transaction, 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 at a make-whole exchange ratio. As required by the terms of the Indenture, the Company delivered 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 of TGIL at a fundamental make-whole exchange ratio up to and including April 26, 2013. There were no bonds tendered or converted as a result of the Change Notice delivery.
	The adjusted conversion rate at September 30, 2013 is 28.3299 shares of common stock per $1,000 principal amount of the Notes (equivalent to a conversion price of $35.30 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.
	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 $8.9 million for the nine months ended September 30, 2013.
	The following table shows the amounts recorded for the Notes as of September 30, 2013 and December 31, 2012:
		September 30,			December 31,
	($ in thousands)	2013			2012
	Liability component
	Outstanding principal	$	150,000		$	150,000
	Unamortized OID		(3,067	)		(5,327	)
	Liability component		146,933			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, TGI 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 TGI’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 TGI with the financial institutions, and were not part of the terms of the Notes.
	In March 2013, as a result of the Canopius Merger Transaction, TGI 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	9 Months Ended
	Sep. 30, 2013
Stock Based Compensation	'
	Note 13—Stock Based Compensation
	2008 Long-Term Equity Compensation Plan (“2008 LTEP”)
	In 2008, TGI’s Board of Directors adopted and its shareholders approved amendments to TGI’s 2004 Long-Term Equity Compensation Plan (as amended and restated, the “2008 LTEP”). Upon consummation of the Canopius Merger Transaction, the Company adopted and approved the 2008 LTEP.
	The 2008 LTEP provided 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 was 2,325,446 of which 30,376 were available for future grants prior to the approval of the 2013 LTIP (as defined below) in May 2013. Following receipt of such approval, no further equity awards have been or will be made under the 2008 LTEP.
	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 LTEP. 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 2,149,118 are available for future grants as of September 30, 2013.
	Restricted Stock
	The following table provides an analysis of restricted stock activity for the nine months ended September 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 – Canopius Merger Transaction”):
		Nine Months Ended September 30,
		2013					2012
		Number of			Weighted		Number			Weighted
		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		377,187			20.27
	Vested		(954,097	)		20.43		(469,236	)		21.1
	Forfeitures		(15,602	)		19.14		(16,528	)		20.74
	Outstanding, September 30,		288,829		$	17.67		1,011,514		$	20.38
	On March 13, 2013, 525,548 shares vested as a result of the Canopius Merger Transaction.
	Stock Options
	The following table provides an analysis of stock option activity for the nine months ended September 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 – Canopius Merger Transaction”):
		Nine Months Ended September 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, September 30		958,976		$	17.78		969,315		$	17.78
	Exercisable, September 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 nine months ended September 30, 2013 and 2012:
		Nine Months Ended
		September 30,
	($ in thousands)	2013			2012
	Restricted stock
	Expense, net of tax	$	8,421		$	4,544
	Value of shares vested		21,058			9,045
	Value of unvested shares		2,022			18,014
	Stock options
	Intrinsic value of outstanding options		-			621
	Intrinsic value of vested outstanding options		-			621
	Unrecognized compensation expense
	Unvested restricted stock, net of tax		2,022			9,405
	Weighted average years over which expense will be recognized		3.4			2.4

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 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 nine months ended September 30, 2013, Tower’s U.S. taxed subsidiaries (excluding the Reciprocal Exchanges) recognized pre-tax losses of approximately $(358.0) million and $(867.3) million, respectively. This resulted in $139.2 million of net operating loss carryforwards in the deferred tax inventory and a net deferred tax asset, before any valuation allowance, of $245.2 million (excluding the Reciprocal Exchanges) as of September 30, 2013. Including the Reciprocal Exchanges, the net deferred tax asset, before any valuation allowance, was $237.9 million.
	At September 30, 2013, a full valuation allowance was recorded against the deferred tax assets. For the nine months ended September 30, 2013, $214.8 million of the valuation allowance was recorded in income tax expense (benefit) in the statement of operations and $30.1 million was recorded in other comprehensive income as a direct charge to shareholder’s equity (as a component of accumulated other comprehensive income). For the three months ended September 30, 2013 $100.9 million of the valuation allowance was recorded in income tax expense (benefit) in the statement of operations and $(4.3) 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 (an additional $57.4 million was recorded in the third quarter of 2013 for a total of $271.4 million in the nine months ended September 30, 2013). 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 0.2% for the three and nine months ended September 30, 2013, 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 $7.4 million of federal excise tax in 2013.

Earnings_Loss_per_Share

Earnings (Loss) per Share	9 Months Ended
	Sep. 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 Canopius Merger Transaction):
		Three Months						Nine Months
		Ended September 30,						Ended September 30,
	(in thousands, except per share amounts)	2013			2012			2013			2012
	Numerator
	Net income (loss) attributable to Tower Group International, Ltd.	$	(347,634	)	$	21,629		$	(842,059	)	$	23,985
	Less: Allocation of income for unvested participating restricted stock		-			(341	)		-			(52	)
	Less: Dividends on unvested participating restricted stock		(48	)		(167	)		(262	)		(514	)
	Net income (loss) available to common shareholders - Basic		(347,682	)		21,121			(842,321	)		23,419
	Reallocation of income for unvested participating restricted stock		-			-			-			-
	Net income (loss) available to common shareholders - Diluted		(347,682	)		21,121			(842,321	)		23,419
	Denominator
	Basic earnings per share denominator		57,138			42,449			53,338			43,045
	Effect of dilutive securities:		-			27			-			85
	Diluted earnings per share denominator		57,138			42,476			53,338			43,130
	Earnings (loss) per share attributable to Tower Group International, Ltd. - Basic
	Common stock:
	Distributed earnings	$	0.17		$	0.17		$	0.5		$	0.5
	Undistributed earnings		(6.25	)		0.33			(16.29	)		0.04
	Total - basic		(6.08	)		0.5			(15.79	)		0.54
	Earnings (loss) per share attributable to Tower Group International, Ltd. - Diluted	$	(6.08	)	$	0.5		$	(15.79	)	$	0.54
	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 nine months ended September 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 nine months ended September 30, 2012, 190,480 and, 188,890, 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	9 Months Ended
	Sep. 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.
	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 NAIC’s 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 entities 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 Reinsurance Company (“CastlePoint Re”), one of its Bermuda based insurance subsidiaries. The 2013 obligations that CastlePoint Re assumes from the U.S. based insurance subsidiaries are then retroceded to Tower Reinsurance, Ltd. (“TRL”), Tower’s other Bermuda based insurance subsidiary. 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. As a result of these transactions, TRL is required to collateralize $243.4 million of assumed reserves in a reinsurance trust for the benefit of TICNY, the lead pool company of the U.S. insurance companies. While TRL had unencumbered liquid assets of $98.6 million at September 30, 2013, and, during the fourth quarter of 2013, TRL received unencumbered cash proceeds totaling $80.9 million from two commuted reinsurance treaties, the required reinsurance trust could not be established until approval was received from the BMA. The BMA approved the transfer of assets from TRL to CastlePoint Re, allowing CastlePoint Re to increase the funding in the reinsurance trust for the benefit of TICNY in January 2014. NYDFS has confirmed this will be acceptable for the purpose of admitted surplus and capital on TICNY’s 2013 statutory basis financial statements.
	The Company projects, based on estimated RBC calculations as of September 30, 2013, that two of its U.S. based insurance subsidiaries (which are New York domiciled) may have minimum capital and surplus below Company Action Level and may not meet the minimum capital and surplus requirements of their respective state regulators. As a result, management has discussed the ACP Re Merger Agreement and provided its RBC forecasts to the regulators to document the Company’s business plan to bring these two U.S. based insurance subsidiaries’ capital and surplus levels above Company Action Level.
	The NYDFS has issued orders for seven of Tower’s insurance subsidiaries, subjecting them to heightened regulatory oversight, which includes providing the NYDFS with increased information with respect to the insurance subsidiaries business, operations and financial condition. In addition, the NYDFS has placed limitations on payments and transactions outside the ordinary course of business and material changes in the insurance subsidiaries’ management and related matters.
	The Massachusetts Division of Insurance (“MDOI”) and Tower management have agreed to certain restrictions on the operations of Tower’s two Massachusetts domiciled insurance subsidiaries. Tower management has agreed to cause these subsidiaries to provide the MDOI 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.
	The Maine Bureau of Insurance entered Corrective Order imposing certain conditions on Maine domestic insurers York Insurance Company of Maine (“YICM”) and North East Insurance Company (“NEIC”). The Corrective Order imposes increased reporting obligations on YICM and NEIC with respect to business operations and financial condition and imposes restrictions on payments or other transfers of assets from YICM and NEIC outside the ordinary course of business.
	As of September 30, 2013, TRL had capital and surplus that did not meet the minimum capital and surplus requirements of the BMA.
	The BMA has issued directives for TRL and CastlePoint Re, subjecting them to heightened regulatory oversight and requiring BMA approval before certain transactions can be executed. Tower has been complying with the directives issued by the BMA.
	Dividends
	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 September 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	9 Months Ended
	Sep. 30, 2013
Segment Information	'
	Note 17—Segment Information
	The accounting policies of the segments are the same as those described in TGIL’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”, in the third quarter of 2013, the Company revised its business segments to present Commercial Insurance, Assumed 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, goodwill and fixed asset impairments and corporate expenses. The Company’s assets and liabilities are not allocated to segments because they 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						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Commercial Insurance Segment
	Revenues
	Premiums earned		$	201,597		$	272,595		$	707,510		$	847,610
	Ceding commission revenue			21,374			2,446			19,888			6,350
	Policy billing fees			1,406			1,358			4,198			4,261
	Total revenues			224,377			276,399			731,596			858,221
	Expenses
	Loss and loss adjustment expenses			303,958			171,246			951,245			632,231
	Underwriting expenses			136,763			96,966			327,871			292,938
	Total expenses			(440,721	)		268,212			1,279,116			925,169
	Underwriting profit (loss)		$	(216,344	)	$	8,187		$	(547,520	)	$	(66,948	)
	Assumed Reinsurance Segment
	Revenues
	Premiums earned		$	51,005		$	24,011		$	145,918		$	84,481
	Ceding commission revenue			-			-			-			-
	Total revenues			51,005			24,011			145,918			84,481
	Expenses
	Loss and loss adjustment expenses			17,216			8,807			64,664			30,469
	Underwriting expenses			12,881			9,389			58,070			30,513
	Total expenses			30,097			18,196			122,734			60,982
	Underwriting profit (loss)		$	20,908		$	5,815		$	23,184		$	23,499
	Personal Insurance Segment
	Revenues
	Premiums earned		$	115,691		$	134,107		$	355,115		$	378,933
	Ceding commission revenue			11,483			5,257			34,391			16,596
	Policy billing fees			1,390			1,775			5,069			5,006
	Total revenues			128,564			141,139			394,575			400,535
	Expenses
	Loss and loss adjustment expenses			62,604			76,043			203,493			210,664
	Underwriting expenses			61,196			58,820			182,892			166,437
	Total expenses			123,800			134,863			386,385			377,101
	Underwriting profit (loss)		$	4,764		$	6,276		$	8,190		$	23,434
	Tower		$	3,132		$	3,504		$	19,288		$	24,717
	Reciprocal Exchanges			1,632			2,772			(11,098	)		(1,283	)
	Total underwriting profit (loss)		$	4,764		$	6,276		$	8,190		$	23,434
	The following table reconciles revenue by segment to consolidated revenues:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Commercial Insurance segment		$	224,377		$	276,399		$	731,596		$	858,221
	Assumed Reinsurance segment			51,005			24,011			145,918			84,481
	Personal Insurance segment			128,564			141,139			394,575			400,535
	Total segment revenues			403,946			441,549			1,272,089			1,343,237
	Net investment income			25,632			31,389			84,351			97,113
	Net realized gains (losses) on investments, including other-than-temporary impairments			18,128			1,145			22,945			4,492
	Corporate and other			(4,804	)(a)		808			518			2,664
	Consolidated revenues		$	442,902		$	474,891		$	1,379,903		$	1,447,506
	(a)	Balance includes $4,662 thousand which relates to the gross-up of ceding commission revenue and commission expense recorded in the statement of operations that relate to the Syndicate 4444 2012 YOA business the Company assumed from Canopius Group and retroceded to an affiliate of Canopius Group. This gross-up is not reflected in the Assumed Re segment revenues as it is not used by management to measure segment profitability or to manage the business. This gross-up has no net effect on income (loss) or segment results.
	The following table reconciles the results of the Company’s individual segments to consolidated income before income taxes:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Commercial Insurance segment underwriting profit (loss)		$	(216,344	)	$	8,187		$	(547,520	)	$	(66,948	)
	Assumed Reinsurance segment underwriting profit (loss)			20,908			5,815			23,184			23,499
Personal Insurance segment underwriting profit (loss)			4,764			6,276			8,190			23,434
Net investment income			25,632			31,389			84,351			97,113
Net realized gains on investments, including other-than-temporary impairments			18,128			1,145			22,945			4,492
Corporate and other			(893	)		(6,948	)		(6,133	)		(11,121	)
Acquisition-related transaction costs			(559	)		(2,679	)		(20,280	)		(4,661	)
Interest expense			(8,008	)		(8,224	)		(23,451	)		(24,737	)
Goodwill and fixed asset impairment			(183,162	)		-			(397,211	)		-
Equity income in unconsolidated affiliate			(3,194	)		-			4,772			-
Income before income taxes		$	(342,728	)	$	34,961		$	(851,153	)	$	41,071

Contingencies

Contingencies	9 Months Ended
	Sep. 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 current and former officers in the United States District Court for the Southern District of New York. The Lang Complaint alleges that Tower and certain of its current and former 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 current and former 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 if it would result in a loss, that the amount of any such loss cannot reasonably be estimated.
	On October 18, 2013, Cinium Financial Services Corporation (“Cinium”) and certain other affiliated parties (collectively, “Plaintiffs”) commenced an action against, among others, Tower, CastlePoint Insurance Company (“CastlePoint”), an indirect wholly owned subsidiary of Tower, and certain officers of Tower (the “New York Action”) 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”). On October 29, 2013, Plaintiffs filed a complaint which revised their initial pleading (the “Complaint”). 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, and for alleged lender liability and fraudulent misrepresentation by the Company.
	On November 19, 2013, a “Stipulation and Order Regarding New York Action” (the “Order”) was entered by the Court of Chancery of the State of Delaware in a separate action largely involving the same parties as the New York Action. Pursuant to the Order, the Plaintiffs will not take any actions in furtherance of the New York Action, including without limitation service of the Complaint, without providing thirty days’ prior written notice. If Plaintiffs do move forward with the New York Action, Tower intends to vigorously defend against it since it believes the Complaint is without merit. Tower believes that it is not probable that the Complaint will result in a loss and if it would result in a loss, that the amount of any such loss cannot reasonably be estimated.
	On January 14, 2014, Derek Wilson, a purported shareholder of Tower, filed a purported class action complaint (the “Wilson Complaint”) against Tower, certain of its current and former directors, ACP Re Ltd. (“ACP Re”), London Acquisition Company Limited (“Merger Sub”), and AmTrust Financial Services, Inc. (“AmTrust”) in the United States District Court for the Southern District of New York. The Wilson Complaint alleges that the members of the Company’s Board of Directors breached their fiduciary duties owed to the shareholders of Tower under Bermuda law by approving Tower’s entry into the ACP Re Merger Agreement and failing to take steps to maximize the value of Tower to its public shareholders, and that Tower, ACP Re, Merger Sub, and AmTrust aided and abetted such breaches of fiduciary duties. The Wilson Complaint also alleges, among other things, that the proposed transaction undervalues Tower, that the process leading up to the ACP Re Merger Agreement was flawed, and that certain provisions of the ACP Re Merger Agreement improperly favor ACP Re and discourage competing offers for the Company. The Wilson Complaint further alleges oppressive conduct against Tower’s shareholders in violation of Bermuda law. The Wilson Complaint seeks, among other things, declaratory and injunctive relief concerning the alleged fiduciary breaches, injunctive relief prohibiting the defendants from consummating the proposed transaction, rescission of the ACP Re Merger Agreement to the extent already implemented, and other forms of equitable relief. The Company believes that it is not probable that the Wilson Complaint will result in a loss, and if it would result in a loss, that the amount of any such 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	9 Months Ended
	Sep. 30, 2013
Subsequent Events	'
	Note 19—Subsequent Events
	Proposed Merger with ACP Re
	On January 3, 2014, Tower entered into an Agreement and Plan of Merger (“ACP Re Merger Agreement”) with ACP Re Ltd. (“ACP Re”), and a wholly-owned subsidiary of ACP Re (“Merger Sub”), pursuant to which, subject to the satisfaction or waiver of the conditions therein, it is expected that Merger Sub will merge with and into Tower, with Tower as the surviving corporation in the merger and a wholly owned subsidiary of ACP Re. The transaction is expected to close by the summer of 2014, subject to the satisfaction or waiver of the closing conditions contained in the ACP Re Merger Agreements. ACP Re is a Bermuda based reinsurance company. The controlling shareholder of ACP Re is a trust established by the founder of AmTrust Financial Services, Inc. (“AmTrust”), National General Holdings Corporation (“NGHC”) and Maiden Holdings, Ltd.
	Pursuant to the terms of the ACP Re Merger Agreement, at the effective time of the merger, each outstanding share of Tower’s common stock, par value $0.01 per share, following the settlement of all outstanding equity awards, will be converted into the right to receive $3.00 in cash, with an aggregate value of approximately $172.1 million.
	Each of the parties has made representations and warranties in the ACP Re Merger Agreement. Tower has agreed to certain covenants and agreements, including, among others, (i) to conduct its business in the ordinary course of business, consistent with past practice, during the period between the execution of the ACP Re Merger Agreement and the closing of the merger, (ii) not to solicit alternate transactions, subject to a customary “fiduciary out” provision which allows Tower under certain circumstances to provide information to and participate in discussions with third parties with respect to unsolicited alternative acquisition proposals that Tower’s Board of Directors has determined, in its good faith judgment, is appropriate in furtherance of the best interests of Tower, and (iii) to call and hold a special shareholders’ meeting and recommend adoption of the ACP Re Merger Agreement.
	Concurrently with the execution of the ACP Re Merger Agreement, several subsidiaries of Tower have entered into two Cut Through Reinsurance Agreements, pursuant to which a subsidiary of AmTrust and a subsidiary of NGHC will provide 100% quota share reinsurance and a cut through endorsement to cover all eligible new and renewal commercial and personal lines business, respectively, and at their option, losses incurred on or after January 1, 2014 on not less than 60% of the in-force business. Tower received confirmation on January 16, 2014 from AmTrust and NGHC that they would exercise such option to reinsure on a cut through basis losses incurred on or after January 1, 2014 under in-force policies with respect to (1) in the case of AmTrust, a significant majority of Tower’s unearned premium reserves as of December 31, 2013 with respect to its ongoing commercial lines business, and (2) in the case of NGHC, 100% of Tower’s unearned premium reserves as of December 31, 2013 with respect to its personal lines segment business. Tower will receive a 20% ceding commission from AmTrust or NGHC on all Tower premiums that are subject to the Cut Through Reinsurance Agreements. Concurrently with the closing of the ACP Re Merger Agreement, ACP Re intends to sell certain of Tower’s commercial lines statutory entities to an affiliate of AmTrust, and certain of Tower’s personal lines statutory entities to an affiliate of National General Insurance Company.
	Concurrently with the execution of the ACP Re Merger Agreement, the controlling shareholder of ACP Re has provided to Tower a guarantee for the payment of the merger consideration, effective upon the closing of the merger.
	The ACP Re Merger Agreement was unanimously approved by the respective Boards of Directors of ACP Re and Tower, and is conditioned, among other things, on: (i) the approval of Tower’s shareholders, (ii) receipt of governmental approvals, including antitrust and insurance regulatory approvals (on January 30, 2014, the Company was granted early termination of the Hart-Scott-Rodino waiting period), (iii) the absence of any law, order or injunction prohibiting the merger, (iv) the accuracy of each party’s representations and warranties (subject to customary materiality qualifiers), and (v) each party’s compliance with its covenants and agreements contained in the ACP Re Merger Agreement. In addition, ACP Re’s obligation to consummate the merger is subject to the non-occurrence of any material adverse effect on Tower, as well as the absence of any insolvency-related event affecting Tower. The transaction is also conditioned on holders of not more than 15% of Tower’s common stock dissenting to the merger.
	There is no financing condition to consummation of the transactions contemplated by the ACP Re Merger Agreement.
	The ACP Re Merger Agreement provides certain termination rights for each of Tower and ACP Re, and further provides that upon termination of the ACP Re Merger Agreement, under certain circumstances, Tower will be obligated to reimburse ACP Re for certain of its transaction expenses, subject to a cap of $2 million, and to pay ACP Re a termination fee of $8.18 million, net of any transaction expenses it has reimbursed.
	Michael H. Lee, the former Chairman, President and Chief Executive Officer of Tower, who beneficially owned approximately 4.2% of the issued and outstanding common stock of Tower as of January 3, 2014, has entered into a support agreement pursuant to which he has agreed to vote his shares in favor of the merger.
	A.M. Best, Fitch and Demotech Downgrade the Company’s Financial Strength and Issuer Credit Ratings
	On December 20, 2013, A.M. Best lowered the financial strength ratings of each of Tower’s insurance subsidiaries from “B++” (Good) to “B” (Fair) (the seventh highest of fifteen rating levels), as well as the issuer credit ratings of each of Tower’s insurance subsidiaries from “bbb” to “bb”. Previously, on October 8, 2013, A.M. Best had downgraded the financial strength rating of each of Tower’s insurance subsidiaries to “B++” (Good) and their respective issuer credit ratings to “bbb” from “a-”. In addition, on December 20, 2013 A.M. Best downgraded the issuer credit rating of TGI as well as the debt rating on its $146.9 million 5.00% senior convertible notes due 2014 (the “Notes”) to “b-” from “bb”. On the same date, A.M. Best also downgraded the financial strength rating of CastlePoint Reinsurance Company, Ltd. (Bermuda) to “B” (Fair) from “B++” (Good) and its issuer credit rating to “bb” from “bbb” and downgraded the issuer credit rating of Tower Group International, Ltd. to “b-” from “bb”. TGI and each of its insurance subsidiaries currently are and will continue to be under review with negative implications pending further discussions between A.M. Best and management. In downgrading Tower’s ratings, A.M. Best stated that its actions “consider the magnitude of the charges taken and the material adverse impact on Tower’s risk-adjusted capitalization, financial leverage, liquidity and coverage ratios,” “consider the reduced financial flexibility [of the Company] given [its] delay in earnings, the decline in shareholder confidence and the corresponding decline in share price” and “reflect the potential for further adverse reserve development, increased competitive challenges and due to the ratings downgrade, potential actions taken by third party reinsurers and lenders.” Following the announcement of the ACP Re merger, on January 10, 2014 A.M. Best maintained the under review status of Tower’s financial strength and issuer credit ratings and revised the implications from “negative” to “developing” for all of these ratings. A.M. Best stated that, “[t]he under review status with developing implications reflects the potential benefits to be garnered from the transaction as well as the potential downside from any additional adverse reserve development and/or any unforeseen events that might transpire up until the close of the transaction…”
	On January 2, 2014, Fitch downgraded Tower’s issuer default rating from “B” to “CC” and the insurer strength ratings of its insurance subsidiaries from “BB” to “B”. On October 7, 2013, Fitch downgraded Tower’s issuer default rating to “B” (the sixth highest of 11 such ratings) from “BBB” and the insurer strength ratings of its insurance subsidiaries to “B” (the fifth highest of Fitch Ratings’ nine such ratings) from “A-”. In downgrading such ratings, Fitch stated that it “is concerned that Tower’s competitive position has been materially damaged, negatively impacting the Company’s financial flexibility and ability to write new business” and that “the magnitude of the second quarter charges was large enough to cause several key ratios to fall well outside of previously established ratings downgrade triggers, which resulted in the multi-notch downgrade.” On January 6, 2014, Fitch revised Tower’s rating watch status to “evolving” from “negative” following the ACP Re merger announcement, and stated that “[t]he Evolving Watch reflects that the ratings could go up if the merger closes; however, ratings could be lowered if the merger does not occur and [the Company] is unsuccessful in addressing upcoming debt maturity or if additional reserve deficiencies develop.”
	On December 24, 2013, Demotech, Inc. (“Demotech”) announced the withdrawal of its Financial Stability Ratings® (FSRs) assigned to the following insurance subsidiaries: Kodiak Insurance Company, Massachusetts Homeland Insurance Company, Tower Insurance Company of New York and York Insurance Company of Maine. Concurrently, Demotech advised that the FSRs assigned to Adirondack Insurance Exchange, Mountain Valley Indemnity Company, New Jersey Skylands Insurance Association and New Jersey Skylands Insurance Company remain under review.
	Previously, on October 7, 2013, Demotech had 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 2013, to result in a significant decrease in the amount of premiums the insurance subsidiaries are able to write. The net written premiums were $237.6 million and $1,093.4 million for the three and nine months ended September 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.
	Regulation
	The NYDFS has issued orders for seven of Tower’s insurance subsidiaries domiciled in the state of New York, subjecting them to heightened regulatory oversight, which includes providing the NYDFS with increased information with respect to the insurance subsidiaries business, operations and financial condition. In addition, the NYDFS has placed limitations on payments and transactions outside the ordinary course of business and material changes in the insurance subsidiaries’ management and related matters.
	The Massachusetts Division of Insurance (“MDOI”) and Tower management have agreed to certain restrictions on the operations of Tower’s two Massachusetts domiciled insurance subsidiaries. Tower Management has agreed to cause these subsidiaries to provide the MDOI 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.
	The Maine Bureau of Insurance entered a Corrective Order imposing certain conditions on Maine domestic insurers York Insurance Company of Maine (“YICM”) and North East Insurance Company (“NEIC”). The Corrective Order imposes increased reporting obligations on YICM and NEIC with respect to business operations and financial condition and imposes restrictions on payments or other transfers of assets from YICM and NEIC outside the ordinary course of business.
	As of September 30, 2013, TRL had capital and surplus that did not meet the minimum capital and surplus requirements of the BMA.
	The BMA has issued directives for TRL and CastlePoint Re, subjecting them to heightened regulatory oversight and required BMA approval before certain transactions can be executed. Tower has been complying with the directives issued by the BMA.
	Reinsurance Agreements
	In the fourth quarter of 2013, the Company commuted certain of its assumed reinsurance agreements. These commutations are not expected to result in material commutation gains or losses to the Company, and have provided $80.9 million of unencumbered liquid assets to TRL.
	Sale of Interest in Canopius Group
	On December 13, 2013, TGI closed a sale to an investment fund managed by Bregal Capital LLP (“Bregal”) of all of the shares of the capital stock of Canopius Group owned by TGI. The initial purchase price for the Canopius shares is $69.7 million (£42.5 million), which has been paid in full to TGI. In addition, if a legally binding contract for the sale or other transfer of shares representing a majority of the voting power of Canopius Group is entered into within six months after the date of TGI’s stock purchase agreement with Bregal, a further cash payment would be made by Bregal to TGI. This additional cash payment would be equivalent to the excess, if any, of (1) one-third of the difference between the amount in British pound sterling paid for the shares previously owned by TGI in such sale and £40.6 million (plus TGI’s share of expenses of such sale), minus (2) £1.95 million. On December 18, 2013, NKSJ Holdings announced that it had entered into an agreement, through its insurance subsidiary Sompo Japan Insurance, Inc. to purchase 100% of the shares of Canopius Group.
	Primarily with proceeds from the sale, TGI has paid in full the $70.0 million outstanding on its credit facility led by Bank of America, N.A., and the credit facility has been terminated.
	Expense Control Initiative
	On November 22, 2013, the Company announced the implementation of an expense control initiative to streamline its operations and focus resources on its most profitable lines of business. As part of this initiative, the Company is completing a workforce reduction affecting approximately 10% of the total employee population of approximately 1,400. The areas that are most significantly impacted are commercial lines underwriting as well as operations. This workforce reduction is expected to result in annualized cost savings of approximately $21.0 million. The Company currently estimates that it will recognize pre-tax charges of approximately $5.0 million in the fourth quarter of 2013 for severance and other one-time termination benefits and other associated costs.
	Resignation of Tower’s Chairman of the Board, President and Chief Executive Officer
	On February 7, 2014, Tower announced that its Chairman of the Board of Directors (the “Board”), President and Chief Executive Officer, Michael H. Lee, resigned, effective immediately, from the Company and the Company’s Board to pursue personal and other career opportunities. In connection with his resignation, Mr. Lee will receive a severance payment calculated pursuant to of his employment agreement.
	Tower also announced that Jan R. Van Gorder, who is the lead independent director of the Board and a member of the Board’s Audit Committee, Compensation Committee and Corporate Governance and Nominating Committee, would be appointed to succeed Mr. Lee as Chairman of the Board, and William W. Fox, Jr., who had served as a member of the Board and of the Board’s Audit Committee and Corporate Governance and Nominating Committee until his resignation from the Board on December 31, 2013, will succeed Mr. Lee as President and Chief Executive Officer of Tower immediately after the filing of the September 30, 2013 Form 10-Q. Following Mr. Lee’s resignation and prior to the filing of the September 30, 2013 Form 10-Q, William E. Hitselberger is the person performing functions of or similar to that of President and Chief Executive Officer of Tower. Mr. Fox’s employment terms were approved by the Board of Directors on February 9, 2014. On February 9, 2014, the Board of Directors appointed Mr. Van Gorder as Chairman of the Board.

Accounting_Policies_and_Basis_1

Accounting Policies and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2013
Basis of Presentation	'
	Basis of Presentation
	The Canopius 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 Canopius 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 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 the Company’s consolidated financial statements as of and for the year ended December 31, 2012 and notes thereto included in the Company’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 nine months ended September 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 $1.8 million. Since this was a non-recurring transaction between entities under common control, assets were transferred at historical book value. The difference in the consideration paid and the book value of the assets transferred was treated as an adjustment to equity. This transaction had no effect on consolidated shareholders’ equity.
Reclassifications and Adjustments	'
	Reclassifications and Adjustments
	Since the Company accounted for the Canopius Merger Transaction as a reverse acquisition and recapitalization, it has retroactively restated Common Stock, Treasury Stock and Paid-in-Capital accounts and earnings per share for periods prior to the Canopius Merger Transaction to reflect the historical capitalization of TGI, adjusted for the 1.1330 conversion ratio as discussed in “Note 4 –Canopius Merger Transaction”. Certain other reclassifications have also been made to prior years’ financial information to conform to the current year presentation, including the changes in segment presentation discussed in “Note 1 – Nature of Business.”
	The table below reflects the previously reported and revised shareholders’ equity accounts resulting from the Canopius Merger Transaction:
	($ in thousands, except per share amounts)	As previously			Revised
		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 September 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.56		$	0.5
	Diluted		0.56			0.5
	Weighted average common shares outstanding
	Basic		38,371			42,449
	Diluted		38,395			42,476
	For the nine-months ended September 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.62		$	0.54
	Diluted		0.62			0.54
	Weighted average common shares outstanding
	Basic		38,929			43,045
	Diluted		38,979			43,130
	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 has considered this guidance in connection with its impairment testing of its indefinite-lived intangible assets. 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.
	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 Canopius Merger Transaction
	The Company has accounted for the Canopius 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 Canopius Merger Transaction was primarily based on the fact that immediately following the close of the Canopius 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 Canopius 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 Canopius 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 Canopius 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 Canopius Merger Transaction, TGI entered into a commutation agreement whereby 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 1 of 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 a quarterly impairment test was required as a result of the reorganization and significant prior years’ loss reserves incurred (see “Note 9 – Loss and Loss Adjustment Expense”). In the third quarter of 2013, as a result of the additional significant prior years’ loss reserves incurred, management concluded a quarterly impairment test was required again as of September 30, 2013 in the preparation of the September 30, 2013 consolidated financial statements.
	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. As of June 30, 2013, the Company reported $55.5 million of goodwill, all of which related to the Personal Insurance reporting unit.
	In conducting the goodwill impairment analysis for the quarter ended September 30, 2013, the Company estimated the Personal Insurance fair values using Tower’s current market capitalization, adjusted for a control premium. Historically, the Company also utilized various market multiple approaches for Personal Insurance reporting unit. However, based upon the significant 2013 events, including A.M. Best’s downgrade to “B” for the insurance subsidiaries, management in its judgment concluded the market capitalization, adjusted for a control premium, was most indicative of a price a market participant would pay for the reporting unit.
	Step 1 of the impairment test as of September 30, 2013 indicated the Personal Insurance unit’s carrying value exceeded its fair value.
	Accordingly, the Company performed a Step 2 impairment test on the Personal Insurance reporting unit. Based on the results, the Company recorded a non-cash goodwill impairment charge of $55.5 million to write-down all of the goodwill in the Personal Insurance reporting unit as of September 30, 2013. As of September 30, 2013, the Company had no goodwill reported on its consolidated balance sheet.
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 TGIL’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”, in the third quarter of 2013, the Company revised its business segments to present Commercial Insurance, Assumed 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, goodwill and fixed asset impairments and corporate expenses. The Company’s assets and liabilities are not allocated to segments because they 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)	9 Months Ended
	Sep. 30, 2013
Restatement on Consolidated Balance Sheets	'
	The effects of the restatement on the consolidated balance sheets are presented in the table below:
		As of December 31, 2012
	($ in thousands, except par value and share amounts)	As			Restated			Effect of
		Previously						Adjustments
		Filed
	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	)
	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)	9 Months Ended
	Sep. 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 Canopius Merger Transaction:
	($ in thousands, except per share amounts)	As previously			Revised
		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 September 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.56		$	0.5
	Diluted		0.56			0.5
	Weighted average common shares outstanding
	Basic		38,371			42,449
	Diluted		38,395			42,476
	For the nine-months ended September 30, 2012
	Earnings (Loss) per Share:
	Basic	$	0.62		$	0.54
	Diluted		0.62			0.54
	Weighted average common shares outstanding
	Basic		38,929			43,045
	Diluted		38,979			43,130

Canopius_Merger_Transaction_Ta

Canopius Merger Transaction (Tables)	9 Months Ended
	Sep. 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					Nine Months Ended
		September 30,					September 30,
	($ in thousands)	2013			2012		2013			2012
	Revenues	$	442,902		$	522,984	$	1,383,047		$	1,502,017
	Net Income (Loss)		(344,132	)		42,333		(829,380	)		52,407

Goodwill_Intangible_Fixed_Asse1

Goodwill, Intangible Fixed Asset Impairments (Tables)	9 Months Ended
	Sep. 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 reorganizations.
	($ in thousands)	Commercial			Personal			Total
		Insurance			Insurance
	Balance, January 1, 2013	$	185,918		$	55,540		$	241,458
	Goodwill from Canopius Merger Transaction		28,131			-			28,131
	Good will from Marine and Energy Acquisition		1,853			-			1,853
	Goodwill impairment		(215,902	)		(55,540	)		(271,442	)
	Total, September 30, 2013	$	-		$	-		$	-

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 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 September 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)
	September 30, 2013
	U.S. Treasury securities		$	395,876		$	1,245		$	(4,017	)	$	393,104		$	-
	U.S. Agency securities			100,417			1,962			(112	)		102,267			-
	Municipal bonds			311,386			9,303			(6,187	)		314,502			-
	Corporate and other bonds
	Finance			201,533			11,512			(3,163	)		209,882			-
	Industrial			394,777			11,786			(4,435	)		402,128			-
	Utilities			45,111			1,501			(1,698	)		44,914			-
	Commercial mortgage-backed securities			215,545			20,066			(1,893	)		233,718			(570	)
	Residential mortgage-backed securities
	Agency backed securities			77,746			1,893			(455	)		79,184			-
	Non-agency backed securities			33,247			4,116			(40	)		37,323			(22	)
	Asset-backed securities			56,326			834			(49	)		57,111			-
	Total fixed-maturity securities			1,831,964			64,218			(22,049	)		1,874,133			(592	)
	Preferred stocks, principally financial sector			21,331			43			(2,392	)		18,982			-
	Common stocks, principally financial and industrial sectors			82,327			9,942			(3,344	)		88,925			-
	Short-term investments			5,925			-			(36	)		5,889			-
	Total, September 30, 2013		$	1,941,547		$	74,203		$	(27,821	)	$	1,987,929		$	(592	)
	Tower		$	1,692,456		$	66,082		$	(22,954	)	$	1,735,584		$	(592	)
	Reciprocal Exchanges			249,091			8,121			(4,867	)		252,345			-
	Total, September 30, 2013		$	1,941,547		$	74,203		$	(27,821	)	$	1,987,929		$	(592	)
	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						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Income
	Fixed-maturity securities		$	19,190		$	24,217		$	60,725		$	74,141
	Equity securities			3,615			7,856			16,907			22,095
	Cash and cash equivalents			511			379			581			1,118
	Other invested assets			4,329			786			10,743			3,932
	Other			36			(258	)		651			150
	Total			27,681			32,980			89,607			101,436
	Expenses
	Investment expenses			(2,049	)		(1,591	)		(5,256	)		(4,323	)
	Net investment income		$	25,632		$	31,389		$	84,351		$	97,113
	Tower			24,899			29,923			82,094			92,448
	Reciprocal Exchanges			2,418			3,142			7,257			9,668
	Elimination of interest on Reciprocal Exchange surplus notes			(1,685	)		(1,676	)		(5,000	)		(5,003	)
	Net investment income		$	25,632		$	31,389		$	84,351		$	97,113
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						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Fixed-maturity securities
	Gross realized gains		$	22,687		$	5,594		$	40,530		$	30,756
	Gross realized losses			(5,762	)		(271	)		(7,624	)		(2,822	)
				16,925			5,323			32,906			27,934
	Equity securities
	Gross realized gains			3,131			5,109			12,690			9,288
	Gross realized losses			(3,458	)		(6,890	)		(20,988	)		(23,050	)
				(327	)		(1,781	)		(8,298	)		(13,762	)
	Other
	Gross realized gains			8,212			726			12,067			2,516
	Gross realized losses			(2,490	)		(1,396	)		(4,393	)		(5,509	)
				5,722			(670	)		7,674			(2,993	)
	Net realized gains (losses) on investments			22,320			2,872			32,282			11,179
	Other-than-temporary impairment losses:
	Fixed-maturity securities			(2,630	)		(438	)		(2,817	)		(1,320	)
	Equity securities			(1,562	)		(1,289	)		(6,520	)		(5,367	)
	Total other-than-temporary impairment losses recognized in earnings			(4,192	)		(1,727	)		(9,337	)		(6,687	)
	Total net realized investment gains (losses)		$	18,128		$	1,145		$	22,945		$	4,492
	Tower		$	17,093		$	80		$	21,083		$	1,108
	Reciprocal Exchanges			1,035			1,065			1,862			3,384
	Total net realized investment gains (losses)		$	18,128		$	1,145		$	22,945		$	4,492
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 nine months ended September 30, 2013 and 2012:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	U.S. Treasury securities		$	(801	)	$	-		$	(801	)	$	-
	U.S. Agency securities			(571	)		-			(571	)		-
	Municipal bonds			(367	)		(113	)		(367	)		(113	)
	Corporate and other bonds			(596	)		(292	)		(596	)		(1,029	)
	Commercial mortgage-backed securities			(361	)		(27	)		(408	)		(430	)
	Residential mortgage-backed securities			(269	)		(6	)		(409	)		(34	)
	Equities			(1,562	)		(1,289	)		(6,520	)		(5,367	)
	Other-than-temporary-impairments			(4,527	)		(1,727	)		(9,672	)		(6,973	)
	Portion of loss recognized in accumulated other comprehensive income (loss)			335			-			335			286
	Impairment losses recognized in earnings		$	(4,192	)	$	(1,727	)	$	(9,337	)	$	(6,687	)
	Tower		$	(4,191	)	$	(1,727	)	$	(9,336	)	$	(6,687	)
	Reciprocal Exchanges			(1	)		-			(1	)		-
	Impairment losses recognized in earnings		$	(4,192	)	$	(1,727	)	$	(9,337	)	$	(6,687	)
Rollforward of Cumulative Amount of Other-Than-Temporary Impairment for Securities 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 held as of September 30, 2013 and 2012 showing the amounts that have been included in earnings on a pretax basis for the three months ended September 30, 2013 and 2012:
			Three Months Ended
			September 30,
	($ in thousands)		2013			2012
	Balance, July 1,		$	4,539		$	6,119
	Additional credit losses recognized during the period, related to securities for which:
	No OTTI has been previously recognized			2,220			405
	OTTI has been previously recognized			410			33
	Reductions due to:
	Securities sold during the period (realized)			(1,925	)		(1,475	)
	Balance, September 30,		$	5,244		$	5,082
	The following table provides a rollforward of the cumulative amounts of credit OTTI for securities held as of September 30, 2013 and 2012 showing the amounts that have been included in earnings on a pretax basis for the nine months ended September 30, 2013 and 2012:
			Nine Months Ended
			September 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			2,407			1,259
	OTTI has been previously recognized			410			61
	Reductions due to:
	Securities sold during the period (realized)			(2,065	)		(8,904	)
	Balance, September 30,		$	5,244		$	5,082
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 September 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
	($ in thousands)		Fair			Unrealized			Fair			Unrealized			Aggregate			Unrealized
			Value			Losses			Value			Losses			Fair Value			Losses
	September 30, 2013
	U.S. Treasury securities		$	289,315		$	(4,017	)	$	-		$	-		$	289,315		$	(4,017	)
	U.S. Agency securities			32,082			(112	)		-			-			32,082			(112	)
	Municipal bonds			107,253			(6,187	)		-			-			107,253			(6,187	)
	Corporate and other bonds
	Finance			59,845			(3,163	)		-			-			59,845			(3,163	)
	Industrial			139,971			(4,277	)		3,700			(158	)		143,671			(4,435	)
	Utilities			31,361			(1,698	)		-			-			31,361			(1,698	)
	Commercial mortgage-backed securities			52,586			(1,893	)		-			-			52,586			(1,893	)
	Residential mortgage-backed securities
	Agency backed			21,729			(454	)		206			(1	)		21,935			(455	)
	Non-agency backed			1,178			(27	)		183			(13	)		1,361			(40	)
	Asset-backed securities			12,407			(49	)		-			-			12,407			(49	)
	Total fixed-maturity securities			747,727			(21,877	)		4,089			(172	)		751,816			(22,049	)
	Preferred stocks			10,694			(2,148	)		6,161			(244	)		16,855			(2,392	)
	Common stocks			33,334			(3,344	)		-			-			33,334			(3,344	)
	Short-term investments			3,889			(36	)		-			-			3,889			(36	)
	Total, September 30, 2013		$	795,644		$	(27,405	)	$	10,250		$	(416	)	$	805,894		$	(27,821	)
	Tower		$	692,839		$	(22,572	)	$	9,697		$	(382	)	$	702,536		$	(22,954	)
	Reciprocal Exchanges			102,805			(4,833	)		553			(34	)		103,358			(4,867	)
	Total, September 30, 2013		$	795,644		$	(27,405	)	$	10,250		$	(416	)	$	805,894		$	(27,821	)
	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 September 30, 2013 and December 31, 2012:
			Tower						Reciprocal Exchanges						Total
	($ in thousands)		Amortized			Fair Value			Amortized			Fair Value			Amortized			Fair Value
			Cost						Cost						Cost
	September 30, 2013
	Remaining Time to Maturity
	Less than one year		$	33,359		$	34,019		$	4,007		$	4,123		$	37,366		$	38,142
	One to five years			574,233			586,305			45,325			47,333			619,558			633,638
	Five to ten years			525,982			529,361			75,673			75,226			601,655			604,587
	More than 10 years			148,759			150,094			41,762			40,335			190,521			190,429
	Mortgage and asset-backed securities			303,291			324,533			79,573			82,804			382,864			407,337
	Total, September 30, 2013		$	1,585,624		$	1,624,312		$	246,340		$	249,821		$	1,831,964		$	1,874,133
	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 September 30, 2013 and December 31, 2012:
	($ in thousands)		September 30,			December 31,
			2013			2012
	Limited partnerships, equity method		$	40,936		$	23,864
	Real estate, amortized cost			5,882			7,422
	Securities reported under the fair value option			42,541			25,000
	Other			8,200			1,500
	Total		$	97,559		$	57,786

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2013
Financial Instruments at Fair Value among Levels	'
	As at September 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
	September 30, 2013
	Fixed-maturity securities
	U.S. Treasury securities	$	-	$	393,104		$	-	$	393,104
	U.S. Agency securities		-		102,267			-		102,267
	Municipal bonds		-		314,502			-		314,502
	Corporate and other bonds		-		656,924			-		656,924
	Commercial mortgage-backed securities		-		233,718			-		233,718
	Residential mortgage-backed securities
	Agency		-		79,184			-		79,184
	Non-agency		-		37,323			-		37,323
	Asset-backed securities		-		57,111			-		57,111
	Total fixed-maturities		-		1,874,133			-		1,874,133
	Equity securities		107,907		-			-		107,907
	Short-term investments		-		5,889			-		5,889
	Total investments at fair value		107,907		1,880,022			-		1,987,929
	Other invested assets (1)		-		-			42,542		42,542
	Other liabilities									-
	Interest rate swap contracts		-		(6,659	)		-		(6,659	)
	Debt and equity securities sold, not yet purchased		-		(21,486	)		-		(21,486	)
	Total, September 30, 2013	$	107,907	$	1,851,877		$	42,542	$	2,002,326
	Tower	$	105,383	$	1,602,056		$	42,542	$	1,749,981
	Reciprocal Exchanges		2,524		249,821			-		252,345
	Total, September 30, 2013	$	107,907	$	1,851,877		$	42,542	$	2,002,326
	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) $42.5 million of the $97.6 million Other invested assets reported on the consolidated balance sheet at September 30, 2013 is reported at fair value. The remaining $55.1 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 $32.8 million of Other invested assets is reported under the equity method of accounting or at amortized cost.
Summary of Changes in Level Three Assets Measured at Fair Value	'
	The following table summarizes the changes in Level 3 assets measured at fair value for the three months ended September 30, 2013 and 2012 for Tower (the Reciprocal Exchanges have no Level 3 assets):
				Three Months Ended
				September 30,
	($ in thousands)			2013			2012
	Beginning balance, July 1,		$		30,250		$	24,914
	Total gains (losses)-realized / unrealized
	Included in net income				-			86
	Included in other comprehensive income (loss)				-			-
	Purchases, issuances and settlements				12,292			-
	Net transfers into (out of) Level 3				-			-
	Ending balance, September 30,	$			42,542		$	25,000
	The following table summarizes the changes in Level 3 assets measured at fair value for the nine months ended September 30, 2013 and 2012 for Tower (the Reciprocal Exchanges have no Level 3 assets):
				Nine Months Ended
				September 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				17,542			-
	Net transfers into (out of) Level 3				-			-
	Ending balance, September 30,	$			42,542		$	25,000

Loss_and_Loss_Adjustment_Expen1

Loss and Loss Adjustment Expense (Tables)	9 Months Ended
	Sep. 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 nine months ended September 30, 2013 and 2012:
		Nine Months Ended September 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			-			-			-
	Reduction in net reserves for ADC (i)		(324,109	)		-			(324,109	)		-			-			-
	Incurred related to:
	Current year		669,830			79,989			749,819			723,642			78,763			802,405
	Prior years unfavorable/(favorable) development		470,510			(927	)		469,583			78,231			(7,272	)		70,959
	Total incurred		1,140,340			79,062			1,219,402			801,873			71,491			873,364
	Paid related to:
	Current year		387,636			53,379			441,015			250,062			56,440			306,502
	Prior years		529,371			19,297			548,668			462,134			36,137			498,271
	Total paid		917,007			72,676			989,683			712,196			92,577			804,773
	Net balance at end of period		1,413,930			89,788			1,503,718			1,304,548			103,935			1,408,483
	Add reinsurance recoverables on unpaid losses		572,611			22,152			594,763			294,488			19,138			313,626
	Balance at September 30,	$	1,986,541		$	111,940		$	2,098,481		$	1,599,036		$	123,073		$	1,722,109
	(i) In the third quarter of 2013, Tower executed the Southport Re ADCs (see “Note 1 - Nature of the Business” for further description). The Southport Re ADCs resulted in a direct reduction to net loss reserves.

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 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 nine months ended September 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		(70,597	)		(1,026	)		78		(71,545	)
	Amounts reclassified from accumulated other comprehensive income, net of tax		(21,418	)		2,522			-		(18,896	)
	Net current period other comprehensive income		(92,015	)		1,496			78		(90,441	)
	Balance at September 30, 2013	$	(4,603	)	$	(4,364	)	$	1,282	$	(7,685	)
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 nine months ended September 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	$	(21,418	)	Other net realized investment gains
			-		Income tax expense
		$	(21,418	)	Total net of income taxes
	Gains (losses) on cash flow hedges interest rate swaps	$	2,522		Interest expense
			-		Income tax expense
		$	2,522		Total net of income taxes

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2013
Borrowings	'
	The Company’s borrowings consisted of the following at September 30, 2013 and December 31, 2012:
		September 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		146,933			126,750			144,673		152,063
	Subordinated debentures		235,058			163,203			235,058		232,678
	Total	$	451,991		$	359,953		$	449,731	$	454,741
Amounts Recorded for Notes	'
	The following table shows the amounts recorded for the Notes as of September 30, 2013 and December 31, 2012:
		September 30,			December 31,
	($ in thousands)	2013			2012
	Liability component
	Outstanding principal	$	150,000		$	150,000
	Unamortized OID		(3,067	)		(5,327	)
	Liability component		146,933			144,673
	Equity component, net of tax	$	7,469		$	7,469

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2013
Analysis of Restricted Stock Activity	'
	The following table provides an analysis of restricted stock activity for the nine months ended September 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 – Canopius Merger Transaction”):
		Nine Months Ended September 30,
		2013					2012
		Number of			Weighted		Number			Weighted
		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		377,187			20.27
	Vested		(954,097	)		20.43		(469,236	)		21.1
	Forfeitures		(15,602	)		19.14		(16,528	)		20.74
	Outstanding, September 30,		288,829		$	17.67		1,011,514		$	20.38
Analysis of Stock Option Activity	'
	The following table provides an analysis of stock option activity for the nine months ended September 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 – Canopius Merger Transaction”):
		Nine Months Ended September 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, September 30		958,976		$	17.78		969,315		$	17.78
	Exercisable, September 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 nine months ended September 30, 2013 and 2012:
		Nine Months Ended
		September 30,
	($ in thousands)	2013			2012
	Restricted stock
	Expense, net of tax	$	8,421		$	4,544
	Value of shares vested		21,058			9,045
	Value of unvested shares		2,022			18,014
	Stock options
	Intrinsic value of outstanding options		-			621
	Intrinsic value of vested outstanding options		-			621
	Unrecognized compensation expense
	Unvested restricted stock, net of tax		2,022			9,405
	Weighted average years over which expense will be recognized		3.4			2.4

Earnings_Loss_per_Share_Tables

Earnings (Loss) per Share (Tables)	9 Months Ended
	Sep. 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 Canopius Merger Transaction):
		Three Months						Nine Months
		Ended September 30,						Ended September 30,
	(in thousands, except per share amounts)	2013			2012			2013			2012
	Numerator
	Net income (loss) attributable to Tower Group International, Ltd.	$	(347,634	)	$	21,629		$	(842,059	)	$	23,985
	Less: Allocation of income for unvested participating restricted stock		-			(341	)		-			(52	)
	Less: Dividends on unvested participating restricted stock		(48	)		(167	)		(262	)		(514	)
	Net income (loss) available to common shareholders - Basic		(347,682	)		21,121			(842,321	)		23,419
	Reallocation of income for unvested participating restricted stock		-			-			-			-
	Net income (loss) available to common shareholders - Diluted		(347,682	)		21,121			(842,321	)		23,419
	Denominator
	Basic earnings per share denominator		57,138			42,449			53,338			43,045
	Effect of dilutive securities:		-			27			-			85
	Diluted earnings per share denominator		57,138			42,476			53,338			43,130
	Earnings (loss) per share attributable to Tower Group International, Ltd. - Basic
	Common stock:
	Distributed earnings	$	0.17		$	0.17		$	0.5		$	0.5
	Undistributed earnings		(6.25	)		0.33			(16.29	)		0.04
	Total - basic		(6.08	)		0.5			(15.79	)		0.54
	Earnings (loss) per share attributable to Tower Group International, Ltd. - Diluted	$	(6.08	)	$	0.5		$	(15.79	)	$	0.54

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2013
Business Segments Results	'
	Business segment results are as follows:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Commercial Insurance Segment
	Revenues
	Premiums earned		$	201,597		$	272,595		$	707,510		$	847,610
	Ceding commission revenue			21,374			2,446			19,888			6,350
	Policy billing fees			1,406			1,358			4,198			4,261
	Total revenues			224,377			276,399			731,596			858,221
	Expenses
	Loss and loss adjustment expenses			303,958			171,246			951,245			632,231
	Underwriting expenses			136,763			96,966			327,871			292,938
	Total expenses			(440,721	)		268,212			1,279,116			925,169
	Underwriting profit (loss)		$	(216,344	)	$	8,187		$	(547,520	)	$	(66,948	)
	Assumed Reinsurance Segment
	Revenues
	Premiums earned		$	51,005		$	24,011		$	145,918		$	84,481
	Ceding commission revenue			-			-			-			-
	Total revenues			51,005			24,011			145,918			84,481
	Expenses
	Loss and loss adjustment expenses			17,216			8,807			64,664			30,469
	Underwriting expenses			12,881			9,389			58,070			30,513
	Total expenses			30,097			18,196			122,734			60,982
	Underwriting profit (loss)		$	20,908		$	5,815		$	23,184		$	23,499
	Personal Insurance Segment
	Revenues
	Premiums earned		$	115,691		$	134,107		$	355,115		$	378,933
	Ceding commission revenue			11,483			5,257			34,391			16,596
	Policy billing fees			1,390			1,775			5,069			5,006
	Total revenues			128,564			141,139			394,575			400,535
	Expenses
	Loss and loss adjustment expenses			62,604			76,043			203,493			210,664
	Underwriting expenses			61,196			58,820			182,892			166,437
	Total expenses			123,800			134,863			386,385			377,101
	Underwriting profit (loss)		$	4,764		$	6,276		$	8,190		$	23,434
	Tower		$	3,132		$	3,504		$	19,288		$	24,717
	Reciprocal Exchanges			1,632			2,772			(11,098	)		(1,283	)
	Total underwriting profit (loss)		$	4,764		$	6,276		$	8,190		$	23,434
Reconciliation of Revenue by Segment to Consolidated Revenues	'
	The following table reconciles revenue by segment to consolidated revenues:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Commercial Insurance segment		$	224,377		$	276,399		$	731,596		$	858,221
	Assumed Reinsurance segment			51,005			24,011			145,918			84,481
	Personal Insurance segment			128,564			141,139			394,575			400,535
	Total segment revenues			403,946			441,549			1,272,089			1,343,237
	Net investment income			25,632			31,389			84,351			97,113
	Net realized gains (losses) on investments, including other-than-temporary impairments			18,128			1,145			22,945			4,492
	Corporate and other			(4,804	)(a)		808			518			2,664
	Consolidated revenues		$	442,902		$	474,891		$	1,379,903		$	1,447,506
	(a)	Balance includes $4,662 thousand which relates to the gross-up of ceding commission revenue and commission expense recorded in the statement of operations that relate to the Syndicate 4444 2012 YOA business the Company assumed from Canopius Group and retroceded to an affiliate of Canopius Group. This gross-up is not reflected in the Assumed Re segment revenues as it is not used by management to measure segment profitability or to manage the business. This gross-up has no net effect on income (loss) or segment results.
Reconciliation of Results of Individual Segments to Consolidated Income Before Income Taxes	'
	The following table reconciles the results of the Company’s individual segments to consolidated income before income taxes:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
	($ in thousands)		2013			2012			2013			2012
	Commercial Insurance segment underwriting profit (loss)		$	(216,344	)	$	8,187		$	(547,520	)	$	(66,948	)
	Assumed Reinsurance segment underwriting profit (loss)			20,908			5,815			23,184			23,499
	Personal Insurance segment underwriting profit (loss)			4,764			6,276			8,190			23,434
	Net investment income			25,632			31,389			84,351			97,113
	Net realized gains on investments, including other-than-temporary impairments			18,128			1,145			22,945			4,492
	Corporate and other			(893	)		(6,948	)		(6,133	)		(11,121	)
	Acquisition-related transaction costs			(559	)		(2,679	)		(20,280	)		(4,661	)
	Interest expense			(8,008	)		(8,224	)		(23,451	)		(24,737	)
	Goodwill and fixed asset impairment			(183,162	)		-			(397,211	)		-
	Equity income in unconsolidated affiliate			(3,194	)		-			4,772			-
	Income before income taxes		$	(342,728	)	$	34,961		$	(851,153	)	$	41,071

Nature_of_Business_Additional_

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

3 Months Ended

6 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

1 Months Ended

1 Months Ended

Sep. 30, 2013

Jun. 30, 2013

Sep. 30, 2012

Jun. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Jul. 08, 2013

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2010

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Jun. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Jan. 03, 2014

Dec. 13, 2013

Nov. 22, 2013

Dec. 20, 2013

Jan. 03, 2014

Jan. 03, 2014

Jan. 03, 2014

Jan. 03, 2014

Dec. 13, 2013

Dec. 31, 2013

Oct. 31, 2013

Agreement

Segment

Marine Energy Acquisition

Marine Energy Acquisition

Convertible Senior Notes

Convertible Senior Notes

Convertible Senior Notes

Maximum

Acp Re Ltd

Acp Re Ltd

Tower

Tower

Tower

Tower Insurance Company of New York

Tower Insurance Company of New York

Tower Insurance Company of New York

Tower Insurance Company of New York

Tower Reinsurance, Ltd.

Tower Reinsurance, Ltd.

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Agreement

Southport Re

Arch

Hannover

New Reinsurance Program

2014 Senior Convertible Notes

Acp Re Ltd

Acp Re Ltd

Tower

Tower

Canopius Group Limited

Tower Reinsurance, Ltd.

Tower Reinsurance, Ltd.

Agreement

Maximum

Maximum

Nature Of Business [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, par value

$0.01

'

'

'

$0.01

'

$0.01

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0.01

'

'

'

'

'

'

'

'

'

'

Equity awards settlement in cash

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3

'

'

'

'

'

'

'

'

'

'

Outstanding equity awards, aggregate value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$172,100,000

'

'

'

'

'

'

'

'

'

'

Unearned premium reserve percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

60.00%

'

'

'

Commission percentage on premium

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20.00%

'

'

'

'

Quota share reinsurance cede, percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

30.00%

17.50%

14.00%

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

Percentage of common stockholders dissenting to the merger

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15.00%

'

'

'

Reimburse transaction expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

'

Termination fee

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

21,000,000

'

-8,180,000

'

'

'

'

'

'

President and Chief Executive Officer of Tower,who beneficially owns percentage of issued and outstanding common stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.20%

'

'

'

'

'

'

'

'

'

'

Loss and loss adjustment expenses

383,778,000

'

256,096,000

'

1,219,402,000

873,364,000

'

'

'

'

'

'

'

143,700,000

470,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of loss reserves covered by reserve study

'

'

'

'

'

'

'

'

'

'

'

'

'

93.00%

93.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Goodwill impairment charge

55,540,000

214,000,000

'

214,000,000

397,211,000

'

'

'

1,900,000

'

'

'

'

'

'

57,400,000

214,000,000

271,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fixed assets impairment charge

125,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of reinsurers

3

'

'

'

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ceded premium earned

368,293,000

'

430,713,000

'

1,208,543,000

1,311,024,000

'

'

'

'

'

'

'

'

'

'

'

'

'

64,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ceding commission revenue

28,195,000

'

7,703,000

'

54,279,000

22,946,000

'

'

'

'

'

'

'

'

'

'

'

'

'

16,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ceded loss and adjustment expenses

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

38,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred gain recognized to be amortized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt carrying amount

'

'

'

'

'

'

'

'

'

150,000,000

150,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

146,900,000

'

'

'

'

'

'

'

Debt instrument interest rate

'

'

'

'

'

'

'

'

'

'

'

5.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.00%

'

'

'

'

'

'

'

Net written premiums

237,600,000

'

'

'

1,093,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Additional collateral requested

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

26,300,000

Amount required to be collateralized against adverse loss reserve development

215,953,000

'

'

'

215,953,000

'

98,581,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

243,400,000

'

'

'

'

'

'

'

'

'

'

'

'

Unencumbered liquid assets

85,668,000

'

'

'

85,668,000

'

17,609,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

98,600,000

'

'

'

'

'

'

'

'

'

'

80,900,000

'

Number of reinsurance treaties commuted

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

Credit facility outstanding

70,000,000

'

'

'

70,000,000

'

70,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

70,000,000

'

'

'

'

'

'

'

'

'

Credit facility terminated

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

70,000,000

'

'

'

'

'

'

'

'

'

Percentage of ownership

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10.70%

'

'

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unearned premiums

'

'

'

'

'

'

'

9,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business combination, cash paid

'

'

'

'

'

'

'

1,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business combination, fair value liabilities

'

'

'

'

'

'

'

400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Goodwill

$0

'

'

'

$0

'

$241,458,000

$1,900,000

$1,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Recovered_Sheet1

Restatement of Previously Issued Financial Statements - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			6 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 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	'	'	$469,583	$70,959	'	$365,000	'	'	'	'	'
Loss and loss adjustment expenses	383,778	256,096	1,219,402	873,364	'	'	'	9,600	21,700	5,700	'
Reinsurance recoverables on unpaid losses	594,763	'	594,763	'	459,457	'	-36,735	-37,000	-27,400	-5,700	'
Premium receivable	387,658	'	387,658	'	412,045	'	-10,067	-11,000	-10,000	-5,600	-7,200
Other operating expenses	$110,187	$85,404	$282,888	$240,575	'	'	'	$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 $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Assets	'	'	'	'
Total investments	$2,085,488	$2,553,505	'	'
Cash and cash equivalents	379,608	102,269	179,414	114,098
Investment income receivable	19,965	25,332	'	'
Investment in unconsolidated affiliate	76,785	71,894	'	'
Premiums receivable	387,658	412,045	'	'
Reinsurance recoverable on paid losses	85,668	17,609	'	'
Reinsurance recoverable on unpaid losses	594,763	459,457	'	'
Prepaid reinsurance premiums	217,916	63,923	'	'
Deferred acquisition costs, net	149,836	181,198	'	'
Intangible assets	80,215	106,768	'	'
Goodwill	0	241,458	'	'
Funds held by reinsured companies	191,901	137,545	'	'
Other assets	362,757	338,769	'	'
Total assets	4,632,560	4,711,772	'	'
Liabilities	'	'	'	'
Loss and loss adjustment expenses	2,098,481	1,895,679	1,722,109	1,632,113
Unearned premium	959,675	921,271	'	'
Reinsurance balances payable	385,123	40,569	'	'
Funds held under reinsurance agreements	215,953	98,581	'	'
Other liabilities	278,635	296,960	'	'
Deferred income taxes	'	24,763	'	'
Debt	451,991	449,731	'	'
Total liabilities	4,409,908	3,727,554	'	'
Stockholders' equity	'	'	'	'
Common stock	574	530	'	'
Treasury stock	-23	-181,435	'	'
Paid-in-capital	814,927	780,036	'	'
Accumulated other comprehensive income	-7,685	82,756	'	'
Retained earnings	-600,039	268,171	'	'
Tower Group, Inc. stockholders' equity	207,754	950,058	'	'
Noncontrolling interests	14,898	34,160	'	'
Total stockholders' equity	222,652	984,218	1,075,226	1,037,131
Total liabilities and stockholders' equity	4,632,560	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	'	'
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	'	'
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 $)	Sep. 30, 2013	Sep. 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		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Common stock	$574	'	$574	'	$530
Treasury stock	-23	'	-23	'	-181,435
Paid-in-capital	814,927	'	814,927	'	780,036
Earnings (Loss) per Share:	'	'	'	'	'
Basic	($6.08)	$0.50	($15.79)	$0.54	'
Diluted	($6.08)	$0.50	($15.79)	$0.54	'
Weighted average common shares outstanding	'	'	'	'	'
Basic	57,138	42,449	53,338	43,045	'
Diluted	57,138	42,476	53,338	43,130	'
As Previously Reported	'	'	'	'	'
Common stock	'	'	'	'	469
Treasury stock	'	'	'	'	-181,435
Paid-in-capital	'	'	'	'	780,097
Earnings (Loss) per Share:	'	'	'	'	'
Basic	'	$0.56	'	$0.62	'
Diluted	'	$0.56	'	$0.62	'
Weighted average common shares outstanding	'	'	'	'	'
Basic	'	38,371	'	38,929	'
Diluted	'	38,395	'	38,979	'
Revised	'	'	'	'	'
Common stock	'	'	'	'	530
Treasury stock	'	'	'	'	-181,435
Paid-in-capital	'	'	'	'	$780,036
Earnings (Loss) per Share:	'	'	'	'	'
Basic	'	$0.50	'	$0.54	'
Diluted	'	$0.50	'	$0.54	'
Weighted average common shares outstanding	'	'	'	'	'
Basic	'	42,449	'	43,045	'
Diluted	'	42,476	'	43,130	'

Canopius_Merger_Transaction_Ad

Canopius Merger Transaction - Additional Information (Detail)

3 Months Ended

6 Months Ended

9 Months Ended

9 Months Ended

1 Months Ended

6 Months Ended

9 Months Ended

1 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Jul. 30, 2012

Jun. 30, 2013

Sep. 30, 2013

Mar. 06, 2013

Aug. 20, 2012

Dec. 13, 2013

Dec. 13, 2013

Mar. 06, 2013

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

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

Canopius Group Limited

Canopius Group Limited

Canopius Group Limited

USD ($)

USD ($)

Restricted Stock

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Subsequent Event

Subsequent Event

Third Party Investors

USD ($)

USD ($)

GBP (£)

USD ($)

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Investments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$26,485,000

'

$74,900,000

$69,700,000

£ 42,500,000

'

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 b Common Sharesb), (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 Canopius 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 TGIbs 2008 Long-Term Equity Compensation Plan or otherwise, automatically vested, free of any forfeiture conditions, and were 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

57,427,243

'

57,427,243

57,427,243

'

43,513,678

'

'

'

'

'

'

'

'

57,432,150

'

'

'

'

'

Percentage of outstanding shares held

'

'

'

'

'

'

'

'

'

'

76.00%

24.00%

'

'

'

'

'

'

'

'

Percentage of outstanding shares sold

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10.70%

10.70%

'

Direct cost of the acquisition

559,000

2,679,000

'

20,280,000

4,661,000

'

20,300,000

11,600,000

10,300,000

8,700,000

'

'

'

'

'

'

'

'

'

'

Unamortized reserve for risk premium

19,100,000

'

19,100,000

19,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reinsurance recoverables

'

'

'

'

'

'

'

'

'

'

'

'

'

446,800,000

0

'

'

'

'

'

Prepaid reinsurance premiums

217,916,000

'

217,916,000

217,916,000

'

63,923,000

'

'

'

'

'

'

'

30,100,000

0

'

'

'

'

'

Funds held under reinsurance agreements, asset

191,901,000

'

191,901,000

191,901,000

'

137,545,000

'

'

'

'

'

'

'

721,900,000

0

'

'

'

'

'

Loss and loss adjustment expenses

383,778,000

256,096,000

'

1,219,402,000

873,364,000

'

'

'

'

'

'

'

'

581,500,000

0

'

'

'

'

'

Unearned premiums

959,675,000

'

959,675,000

959,675,000

'

921,271,000

'

'

'

'

'

'

'

38,100,000

0

'

'

'

'

'

Funds held under reinsurance agreements, asset

215,953,000

'

215,953,000

215,953,000

'

98,581,000

'

'

'

'

'

'

'

576,300,000

0

'

'

'

'

'

Funds at Lloyds unencumbered

30,300,000

'

30,300,000

30,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Consolidated revenue since effective date of merger

'

'

96,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Consolidated net income (loss) since effective date of merger

'

'

($3,500,000)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preliminary_Purchase_Considera

Preliminary Purchase Consideration (Detail) (Canopius Group Limited, USD $)	Sep. 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 $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Aug. 20, 2012	Sep. 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	$0	$241,458	$28,131	'	'

Pro_Forma_Financial_Informatio

Pro Forma Financial Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Business Acquisition, Pro Forma Information [Line Items]	'	'	'	'
Revenues	$442,902	$522,984	$1,383,047	$1,502,017
Net Income (Loss)	($344,132)	$42,333	($829,380)	$52,407

Goodwill_Intangible_Fixed_Asse2

Goodwill, Intangible Fixed Asset Impairments - Additional Information (Detail) (USD $)

1 Months Ended

3 Months Ended

6 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

6 Months Ended

9 Months Ended

Mar. 13, 2013

Sep. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Jul. 08, 2013

Sep. 30, 2013

Sep. 30, 2013

Jun. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Jun. 30, 2013

Dec. 31, 2012

Segment

Marine Energy Acquisition

Marine Energy Acquisition

Minimum

Maximum

Customer relationships

Customer relationships

Personal Insurance

Personal Insurance

Personal Insurance

Intangible Assets And Goodwill [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Goodwill from Merger Transaction

$28,100,000

'

'

'

'

'

$1,853,000

'

'

'

'

'

'

'

'

Number of business segments

'

'

'

'

3

'

'

'

'

'

'

'

'

'

'

Goodwill impairment charge

'

55,540,000

214,000,000

214,000,000

397,211,000

'

1,900,000

'

'

'

'

'

55,540,000

'

'

Goodwill

'

0

'

'

0

241,458,000

1,900,000

1,900,000

'

'

'

'

'

55,500,000

55,540,000

Impairment of intangible assets

'

'

'

'

'

'

'

'

'

'

3,800,000

18,100,000

'

'

'

Intangible assets

'

'

'

'

'

'

'

'

'

'

'

5,000,000

'

'

'

Gross fixed assets and capital leases

'

'

'

'

'

194,000,000

'

'

'

'

'

'

'

'

'

Accumulated depreciation

'

'

'

'

'

54,700,000

'

'

'

'

'

'

'

'

'

Net fixed assets and capital leases

'

'

'

'

'

139,300,000

'

'

'

'

'

'

'

'

'

Liquidation value analysis range, description

'

'(ii) performing an orderly liquidation value analysis ranging from 0%-15% for furniture, leasehold improvements and computer equipment, and concluded the fixed assets were impaired as of September 30, 2013.

'

'

'

'

'

'

'

'

'

'

'

'

'

Fixed assets impairment charge

'

125,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Other assets

'

$20,700,000

'

'

$20,700,000

'

'

'

'

'

'

'

'

'

'

Percentage Of Liquidation Preference on fixed assets

'

'

'

'

'

'

'

'

0.00%

15.00%

'

'

'

'

'

Summary_of_Goodwill_by_Reporti

Summary of Goodwill by Reporting Units (Detail) (USD $)

1 Months Ended

3 Months Ended

6 Months Ended

9 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Mar. 13, 2013

Sep. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Jul. 08, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Jun. 30, 2013

Canopius Group Limited

Marine Energy Acquisition

Marine Energy Acquisition

Commercial Insurance

Commercial Insurance

Commercial Insurance

Personal Insurance

Personal Insurance

Canopius Group Limited

Marine Energy Acquisition

Goodwill [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Opening balance

'

'

'

$241,458

$241,458

'

'

$1,900

$185,918

'

'

$55,540

$55,500

Goodwill acquired

28,100

'

'

'

'

28,131

1,853

'

'

28,131

1,853

'

'

Goodwill impairment

'

-55,540

-214,000

-214,000

-397,211

'

-1,900

'

-215,902

'

'

-55,540

'

Closing balance

'

$0

'

'

$0

$28,131

$1,900

$1,900

'

'

'

'

$55,500

Variable_Interest_Entities_VIE1

Variable Interest Entities ("VIEs") - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Variable Interest Entity [Line Items]	'	'	'	'
Total revenues	$442,902	$474,891	$1,379,903	$1,447,506
Total expenses	604,274	439,930	1,843,617	1,406,435
Net income (loss)	3,502	4,318	-6,978	7,766
Reciprocal Exchanges	'	'	'	'
Variable Interest Entity [Line Items]	'	'	'	'
Total revenues	47,100	50,200	143,500	149,600
Total expenses	43,600	45,900	150,500	141,800
Net income (loss)	$3,500	$4,300	($7,000)	$7,800

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 $)	Sep. 30, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	$1,941,547		$2,344,283
Gross Unrealized Gains	74,203		159,147
Gross Unrealized Losses	-27,821		-7,711
Investments	1,987,929		2,495,719
Unrealized OTTI Losses	-592	[1]	-6	[1]
Tower	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	1,692,456		2,075,189
Gross Unrealized Gains	66,082		141,614
Gross Unrealized Losses	-22,954		-7,210
Investments	1,735,584		2,209,593
Unrealized OTTI Losses	-592	[1]	-6	[1]
Reciprocal Exchanges	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	249,091		269,094
Gross Unrealized Gains	8,121		17,533
Gross Unrealized Losses	-4,867		-501
Investments	252,345		286,126
Fixed-maturity securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	1,831,964		2,190,186
Gross Unrealized Gains	64,218		157,463
Gross Unrealized Losses	-22,049		-2,938
Investments	1,874,133		2,344,711
Unrealized OTTI Losses	-592	[1]	-6	[1]
Fixed-maturity securities | U.S. Treasury Securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	395,876		183,462
Gross Unrealized Gains	1,245		1,500
Gross Unrealized Losses	-4,017		-13
Investments	393,104		184,949
Fixed-maturity securities | U.S. Agency securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	100,417		98,502
Gross Unrealized Gains	1,962		4,351
Gross Unrealized Losses	-112		-76
Investments	102,267		102,777
Fixed-maturity securities | Municipal Bonds	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	311,386		633,373
Gross Unrealized Gains	9,303		52,914
Gross Unrealized Losses	-6,187		-244
Investments	314,502		686,043
Fixed-maturity securities | Corporate Securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Investments	656,924		746,665
Fixed-maturity securities | Corporate Securities | Finance	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	201,533		233,849
Gross Unrealized Gains	11,512		21,293
Gross Unrealized Losses	-3,163		-1,095
Investments	209,882		254,047
Fixed-maturity securities | Corporate Securities | Industrial	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	394,777		412,465
Gross Unrealized Gains	11,786		26,556
Gross Unrealized Losses	-4,435		-868
Investments	402,128		438,153
Fixed-maturity securities | Corporate Securities | Utilities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	45,111		51,698
Gross Unrealized Gains	1,501		2,958
Gross Unrealized Losses	-1,698		-191
Investments	44,914		54,465
Fixed-maturity securities | Commercial mortgage-backed securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	215,545		211,819
Gross Unrealized Gains	20,066		30,375
Gross Unrealized Losses	-1,893		-141
Investments	233,718		242,053
Unrealized OTTI Losses	-570	[1]	'
Fixed-maturity securities | Residential mortgage-backed securities, Agency backed securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	77,746		283,652
Gross Unrealized Gains	1,893		12,326
Gross Unrealized Losses	-455		-262
Investments	79,184		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	33,247		38,615
Gross Unrealized Gains	4,116		3,575
Gross Unrealized Losses	-40		-34
Investments	37,323		42,156
Unrealized OTTI Losses	-22	[1]	-6	[1]
Fixed-maturity securities | Asset-Backed Securities	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	56,326		42,751
Gross Unrealized Gains	834		1,615
Gross Unrealized Losses	-49		-14
Investments	57,111		44,352
Preferred stocks	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	21,331		31,272
Gross Unrealized Gains	43		730
Gross Unrealized Losses	-2,392		-481
Investments	18,982		31,521
Common Stocks	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	82,327		118,076
Gross Unrealized Gains	9,942		953
Gross Unrealized Losses	-3,344		-4,292
Investments	88,925		114,737
Short-term investments	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Cost or Amortized Cost	5,925		4,749
Gross Unrealized Gains	'		1
Gross Unrealized Losses	-36		'
Investments	$5,889		$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 $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
	Investment
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Restricted assets, cash and cash equivalents	$48,700,000	'	'
Investment, carrying values	1,941,547,000	'	2,344,283,000
Proceeds from sale of equity securities	970,837,000	1,149,473,000	'
Number of securities in unrealized loss position not deemed OTTI	573	'	'
Unrealized losses	27,821,000	'	7,711,000
Unrealized losses related to securities in loss position for more than 12 months	416,000	'	577,000
Future funding commitments including not limited to limited partnerships	51,000,000	'	'
Fixed-maturity securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Proceeds from sale or maturity of fixed maturity securities	1,300,000,000	1,300,000,000	'
Number of securities in unrealized loss position not deemed OTTI	556	'	'
Unrealized losses	22,000,000	'	'
Percentage of fixed maturity securities in unrealized loss position below amortized cost	2.80%	'	'
Number of securities in unrealized loss position for more than 12 months	44	'	'
Unrealized losses related to securities in loss position for more than 12 months	170,000	'	'
Equity securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Proceeds from sale of equity securities	970,800,000	1,149,500,000	'
Common Stocks	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Number of securities in unrealized loss position not deemed OTTI	11	'	'
Unrealized losses	3,300,000	'	'
US Treasury Notes and Other Securities | Held by Counterparties	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Restricted assets, cash and cash equivalents	467,800,000	'	'
Investment, carrying values	'	'	311,300,000
Municipal Bonds Corporate Securities And US Treasury Securities | Fixed-maturity securities	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Unrealized losses	19,500,000	'	'
Tower	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Investment, carrying values	1,692,456,000	'	2,075,189,000
Unrealized losses	22,954,000	'	7,210,000
Unrealized losses related to securities in loss position for more than 12 months	$382,000	'	$478,000
Tower | Other	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Number of securities purchased	7	'	'

Summary_of_Major_Categories_of

Summary of Major Categories of Net Investment Income (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	$27,681	$32,980	$89,607	$101,436
Investment expenses	-2,049	-1,591	-5,256	-4,323
Net investment income	25,632	31,389	84,351	97,113
Tower	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Net investment income	24,899	29,923	82,094	92,448
Reciprocal Exchanges	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Net investment income	2,418	3,142	7,257	9,668
Consolidation, Eliminations	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Net investment income	-1,685	-1,676	-5,000	-5,003
Fixed-maturity securities	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	19,190	24,217	60,725	74,141
Equity securities	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	3,615	7,856	16,907	22,095
Cash and cash equivalents	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	511	379	581	1,118
Other invested asset	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	4,329	786	10,743	3,932
Other	'	'	'	'
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]	'	'	'	'
Income	$36	($258)	$651	$150

Summary_of_Gross_Realized_Gain

Summary of Gross Realized Gains, Losses and Impairment Write-Downs on Investments (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Gain (Loss) on Investments [Line Items]	'	'	'	'
Net realized gains (losses) on investments	$22,320	$2,872	$32,282	$11,179
Other-than-temporary impairment losses	-4,192	-1,727	-9,337	-6,687
Total net realized investment gains (losses)	18,128	1,145	22,945	4,492
Tower	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Other-than-temporary impairment losses	-4,191	-1,727	-9,336	-6,687
Total net realized investment gains (losses)	17,093	80	21,083	1,108
Reciprocal Exchanges	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Other-than-temporary impairment losses	-1	'	-1	'
Total net realized investment gains (losses)	1,035	1,065	1,862	3,384
Fixed-maturity securities	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Gross realized gains	22,687	5,594	40,530	30,756
Gross realized losses	-5,762	-271	-7,624	-2,822
Net realized gains (losses) on investments	16,925	5,323	32,906	27,934
Other-than-temporary impairment losses	-2,630	-438	-2,817	-1,320
Equity securities	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Gross realized gains	3,131	5,109	12,690	9,288
Gross realized losses	-3,458	-6,890	-20,988	-23,050
Net realized gains (losses) on investments	-327	-1,781	-8,298	-13,762
Other-than-temporary impairment losses	-1,562	-1,289	-6,520	-5,367
Other	'	'	'	'
Gain (Loss) on Investments [Line Items]	'	'	'	'
Gross realized gains	8,212	726	12,067	2,516
Gross realized losses	-2,490	-1,396	-4,393	-5,509
Net realized gains (losses) on investments	$5,722	($670)	$7,674	($2,993)

Amount_of_FixedMaturity_and_Eq

Amount of Fixed-Maturity and Equity Securities that were Other-Than-Temporary Impairment (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	($4,527)	($1,727)	($9,672)	($6,973)
Portion of loss recognized in accumulated other comprehensive income (loss)	335	'	335	286
Other-than-temporary impairment losses	-4,192	-1,727	-9,337	-6,687
Tower	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairment losses	-4,191	-1,727	-9,336	-6,687
Reciprocal Exchanges	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairment losses	-1	'	-1	'
U.S. Treasury Securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	-801	'	-801	'
U.S. Agency securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	-571	'	-571	'
Municipal Bonds	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	-367	-113	-367	-113
Corporate Securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	-596	-292	-596	-1,029
Commercial mortgage-backed securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	-361	-27	-408	-430
Residential mortgage-backed securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	-269	-6	-409	-34
Equity securities	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Other-than-temporary impairments	($1,562)	($1,289)	($6,520)	($5,367)

Rollforward_of_Cumulative_Amou

Rollforward of Cumulative Amount of Other-Than-Temporary Impairment for Securities Held Showing Amounts that have been Included in Earnings on Pretax Basis (Detail) (Tower, USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Tower	'	'	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'	'	'
Balance at beginning of period	$4,539	$6,119	$4,492	$12,666
Additional credit losses recognized during the period, related to securities for which no OTTI has been previously recognized	2,220	405	2,407	1,259
Additional credit losses recognized during the period, related to securities for which OTTI has been previously recognized	410	33	410	61
Reductions due to Securities sold during the period (realized)	-1,925	-1,475	-2,065	-8,904
Balance at end of period	$5,244	$5,082	$5,244	$5,082

Information_Regarding_Invested

Information Regarding Invested Assets that were in Unrealized Loss Position (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	$795,644	$328,618
Less than 12 Months, Unrealized Losses	-27,405	-7,134
12 Months or Longer, Fair Value	10,250	15,110
12 Months or Longer, Unrealized Losses	-416	-577
Total, Aggregate Fair Value	805,894	343,728
Total, Unrealized Losses	-27,821	-7,711
Tower	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	692,839	270,609
Less than 12 Months, Unrealized Losses	-22,572	-6,732
12 Months or Longer, Fair Value	9,697	13,338
12 Months or Longer, Unrealized Losses	-382	-478
Total, Aggregate Fair Value	702,536	283,947
Total, Unrealized Losses	-22,954	-7,210
Reciprocal Exchanges	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	102,805	58,009
Less than 12 Months, Unrealized Losses	-4,833	-402
12 Months or Longer, Fair Value	553	1,772
12 Months or Longer, Unrealized Losses	-34	-99
Total, Aggregate Fair Value	103,358	59,781
Total, Unrealized Losses	-4,867	-501
Fixed-maturity securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	747,727	263,342
Less than 12 Months, Unrealized Losses	-21,877	-2,687
12 Months or Longer, Fair Value	4,089	9,386
12 Months or Longer, Unrealized Losses	-172	-251
Total, Aggregate Fair Value	751,816	272,728
Total, Unrealized Losses	-22,049	-2,938
Fixed-maturity securities | U.S. Treasury Securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	289,315	44,347
Less than 12 Months, Unrealized Losses	-4,017	-13
Total, Aggregate Fair Value	289,315	44,347
Total, Unrealized Losses	-4,017	-13
Fixed-maturity securities | U.S. Agency securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	32,082	22,345
Less than 12 Months, Unrealized Losses	-112	-76
Total, Aggregate Fair Value	32,082	22,345
Total, Unrealized Losses	-112	-76
Fixed-maturity securities | Municipal Bonds	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	107,253	21,532
Less than 12 Months, Unrealized Losses	-6,187	-235
12 Months or Longer, Fair Value	'	251
12 Months or Longer, Unrealized Losses	'	-9
Total, Aggregate Fair Value	107,253	21,783
Total, Unrealized Losses	-6,187	-244
Fixed-maturity securities | Corporate Securities | Finance	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	59,845	16,853
Less than 12 Months, Unrealized Losses	-3,163	-1,095
Total, Aggregate Fair Value	59,845	16,853
Total, Unrealized Losses	-3,163	-1,095
Fixed-maturity securities | Corporate Securities | Industrial	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	139,971	53,576
Less than 12 Months, Unrealized Losses	-4,277	-666
12 Months or Longer, Fair Value	3,700	4,188
12 Months or Longer, Unrealized Losses	-158	-202
Total, Aggregate Fair Value	143,671	57,764
Total, Unrealized Losses	-4,435	-868
Fixed-maturity securities | Corporate Securities | Utilities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	31,361	20,143
Less than 12 Months, Unrealized Losses	-1,698	-191
12 Months or Longer, Fair Value	'	7
Total, Aggregate Fair Value	31,361	20,150
Total, Unrealized Losses	-1,698	-191
Fixed-maturity securities | Commercial mortgage-backed securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	52,586	23,223
Less than 12 Months, Unrealized Losses	-1,893	-141
12 Months or Longer, Fair Value	'	95
Total, Aggregate Fair Value	52,586	23,318
Total, Unrealized Losses	-1,893	-141
Fixed-maturity securities | Residential mortgage-backed securities, Agency backed securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	21,729	59,009
Less than 12 Months, Unrealized Losses	-454	-261
12 Months or Longer, Fair Value	206	25
12 Months or Longer, Unrealized Losses	-1	-1
Total, Aggregate Fair Value	21,935	59,034
Total, Unrealized Losses	-455	-262
Fixed-maturity securities | Residential mortgage-backed securities, Non-agency backed securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	1,178	815
Less than 12 Months, Unrealized Losses	-27	-6
12 Months or Longer, Fair Value	183	588
12 Months or Longer, Unrealized Losses	-13	-28
Total, Aggregate Fair Value	1,361	1,403
Total, Unrealized Losses	-40	-34
Fixed-maturity securities | Asset-Backed Securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	12,407	1,499
Less than 12 Months, Unrealized Losses	-49	-3
12 Months or Longer, Fair Value	'	4,232
12 Months or Longer, Unrealized Losses	'	-11
Total, Aggregate Fair Value	12,407	5,731
Total, Unrealized Losses	-49	-14
Preferred stocks	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	10,694	9,716
Less than 12 Months, Unrealized Losses	-2,148	-155
12 Months or Longer, Fair Value	6,161	5,724
12 Months or Longer, Unrealized Losses	-244	-326
Total, Aggregate Fair Value	16,855	15,440
Total, Unrealized Losses	-2,392	-481
Common Stocks	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	33,334	55,560
Less than 12 Months, Unrealized Losses	-3,344	-4,292
Total, Aggregate Fair Value	33,334	55,560
Total, Unrealized Losses	-3,344	-4,292
Short-term investments	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 Months, Fair Value	3,889	'
Less than 12 Months, Unrealized Losses	-36	'
Total, Aggregate Fair Value	3,889	'
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 $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than one year, amortized cost	$37,366	$32,760
One to five years, amortized cost	619,558	535,515
Five to ten years, amortized cost	601,655	641,036
More than 10 years, amortized cost	190,521	404,038
Mortgage and asset-backed securities, amortized cost	382,864	576,837
Total at end of period, amortized cost	1,831,964	2,190,186
Less than one year, fair value	38,142	33,329
One to five years, fair value	633,638	557,798
Five to ten years, fair value	604,587	687,720
More than 10 years, fair value	190,429	441,587
Mortgage and asset-backed securities, fair value	407,337	624,277
Total at end of period, fair value	1,874,133	2,344,711
Tower	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than one year, amortized cost	33,359	30,082
One to five years, amortized cost	574,233	489,939
Five to ten years, amortized cost	525,982	564,556
More than 10 years, amortized cost	148,759	346,410
Mortgage and asset-backed securities, amortized cost	303,291	495,249
Total at end of period, amortized cost	1,585,624	1,926,236
Less than one year, fair value	34,019	30,614
One to five years, fair value	586,305	510,523
Five to ten years, fair value	529,361	607,711
More than 10 years, fair value	150,094	379,045
Mortgage and asset-backed securities, fair value	324,533	536,255
Total at end of period, fair value	1,624,312	2,064,148
Reciprocal Exchanges	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than one year, amortized cost	4,007	2,678
One to five years, amortized cost	45,325	45,576
Five to ten years, amortized cost	75,673	76,480
More than 10 years, amortized cost	41,762	57,628
Mortgage and asset-backed securities, amortized cost	79,573	81,588
Total at end of period, amortized cost	246,340	263,950
Less than one year, fair value	4,123	2,715
One to five years, fair value	47,333	47,275
Five to ten years, fair value	75,226	80,009
More than 10 years, fair value	40,335	62,542
Mortgage and asset-backed securities, fair value	82,804	88,022
Total at end of period, fair value	$249,821	$280,563

Composition_of_Other_Invested_

Composition of Other Invested Assets (Detail) (Tower, USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]	'	'
Other invested assets	$97,559	$57,786
Limited partnerships, equity method	'	'
Schedule of Investments [Line Items]	'	'
Other invested assets	40,936	23,864
Real estate, amortized cost	'	'
Schedule of Investments [Line Items]	'	'
Other invested assets	5,882	7,422
Securities reported under the fair value option	'	'
Schedule of Investments [Line Items]	'	'
Other invested assets	42,541	25,000
Other	'	'
Schedule of Investments [Line Items]	'	'
Other invested assets	$8,200	$1,500

Financial_Instruments_at_Fair_

Financial Instruments at Fair Value among Levels (Detail) (USD $)	Sep. 30, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	$1,987,929		$2,495,719
Other invested assets	42,542	[1]	25,000	[2]
Interest rate swap contracts	-6,659		-9,016
Debt and equity securities sold, not yet purchased	-21,486		-17,101
Total investments and Other liabilities	2,002,326		2,494,602
Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	1,735,584		2,209,593
Total investments and Other liabilities	1,749,981		2,208,475
Reciprocal Exchanges	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	252,345		286,126
Total investments and Other liabilities	252,345		286,127
Level 1	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	107,907		146,258
Total investments and Other liabilities	107,907		146,258
Level 1 | Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	105,383		140,695
Level 1 | Reciprocal Exchanges	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	2,524		5,563
Level 2	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	1,880,022		2,349,461
Interest rate swap contracts	-6,659		-9,016
Debt and equity securities sold, not yet purchased	-21,486		-17,101
Total investments and Other liabilities	1,851,877		2,323,344
Level 2 | Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	1,602,056		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	249,821		280,564
Level 3	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Other invested assets	42,542	[1]	25,000	[2]
Total investments and Other liabilities	42,542		25,000
Level 3 | Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Total investments and Other liabilities	42,542		25,000
Fixed-maturity securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	1,874,133		2,344,711
Fixed-maturity securities | U.S. Treasury Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	393,104		184,949
Fixed-maturity securities | U.S. Agency securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	102,267		102,777
Fixed-maturity securities | Municipal Bonds	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	314,502		686,043
Fixed-maturity securities | Corporate Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	656,924		746,665
Fixed-maturity securities | Commercial mortgage-backed securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	233,718		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	79,184		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	37,323		42,156
Fixed-maturity securities | Asset-Backed Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	57,111		44,352
Fixed-maturity securities | Level 2	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	1,874,133		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	393,104		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	102,267		102,777
Fixed-maturity securities | Level 2 | Municipal Bonds	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	314,502		686,043
Fixed-maturity securities | Level 2 | Corporate Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	656,924		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	233,718		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	79,184		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	37,323		42,156
Fixed-maturity securities | Level 2 | Asset-Backed Securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	57,111		44,352
Equity securities	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	107,907		146,258
Equity securities | Level 1	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	107,907		146,258
Short-term investments	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	5,889		4,750
Short-term investments | Level 2	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Investments	$5,889		$4,750
[1]	$42.5 million of the $97.6 million Other invested assets reported on the consolidated balance sheet at September 30, 2013 is reported at fair value. The remaining $55.1 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 $)	Sep. 30, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Other invested assets, fair value	$42,542,000	[1]	$25,000,000	[2]
Other invested assets, amortized cost	55,100,000		32,800,000
Tower	'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'
Other invested asset	$97,559,000		$57,786,000
[1]	$42.5 million of the $97.6 million Other invested assets reported on the consolidated balance sheet at September 30, 2013 is reported at fair value. The remaining $55.1 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	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 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	$1,100,000	$300,000	'
Tower | Other	'	'	'
Fair Value [Line Items]	'	'	'
Number of securities purchased	'	7	'

Summary_of_Changes_in_Level_Th

Summary of Changes in Level Three Assets Measured at Fair Value (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'	'	'
Beginning balance	$30,250	$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	12,292	'	17,542	'
Net transfers into (out of) Level 3	'	'	'	'
Ending balance	$42,542	$25,000	$42,542	$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	9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2013		Sep. 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		-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		'
Reduction in net reserves for ADC	'	-324,109	[1]	'
Incurred related to:	'	'		'
Current year	'	749,819		802,405
Prior years unfavorable/(favorable) development	'	469,583		70,959
Total incurred	'	1,219,402		873,364
Paid related to:	'	'		'
Current year	'	441,015		306,502
Prior years	'	548,668		498,271
Total paid	'	989,683		804,773
Net balance at end of period	'	1,503,718		1,408,483
Add reinsurance recoverables on unpaid losses	'	594,763		313,626
Net balance at end of year	'	2,098,481		1,722,109
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		-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		'
Reduction in net reserves for ADC	'	-324,109	[1]	'
Incurred related to:	'	'		'
Current year	'	669,830		723,642
Prior years unfavorable/(favorable) development	325,600	470,510		78,231
Total incurred	'	1,140,340		801,873
Paid related to:	'	'		'
Current year	'	387,636		250,062
Prior years	'	529,371		462,134
Total paid	'	917,007		712,196
Net balance at end of period	'	1,413,930		1,304,548
Add reinsurance recoverables on unpaid losses	'	572,611		294,488
Net balance at end of year	'	1,986,541		1,599,036
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		-11,253
Liability for Unpaid Claims and Claims Adjustment Expense, Net	'	83,402		125,021
Incurred related to:	'	'		'
Current year	'	79,989		78,763
Prior years unfavorable/(favorable) development	'	-927		-7,272
Total incurred	'	79,062		71,491
Paid related to:	'	'		'
Current year	'	53,379		56,440
Prior years	'	19,297		36,137
Total paid	'	72,676		92,577
Net balance at end of period	'	89,788		103,935
Add reinsurance recoverables on unpaid losses	'	22,152		19,138
Net balance at end of year	'	$111,940		$123,073
[1]	In the third quarter of 2013, Tower executed the Southport Re ADCs (see "Note 1 - Nature of the Business" for further description). The Southport Re ADCs resulted in a direct reduction to net loss reserves.

Loss_and_Loss_Adjustment_Expen2

Loss and Loss Adjustment Expense - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Jun. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2012

Sep. 30, 2012

Sep. 30, 2012

Sep. 30, 2012

Actuarial Gain Loss

Offset

Workers' Compensation

Commercial Automobile Liability

Commercial Package Liability

Other liability

Canopius Bermuda

Tower

Tower

Tower

Tower

Tower

Tower

Tower

Tower

Tower

Tower

Tower

Tower

Tower

Tower

Specialty Insurance and Reinsurance

Commercial Insurance

Commercial Insurance

Personal Insurance

Personal Insurance

Workers' Compensation

Commercial Automobile Liability

Terminated Programs

Assumed Reinsurance Segment

Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss and loss adjustment expenses ratio

104.20%

59.50%

100.90%

66.60%

'

'

'

'

'

'

'

'

110.20%

'

60.80%

105.00%

67.70%

'

'

'

'

'

'

'

'

'

Prior years unfavorable/(favorable) development

'

'

$469,583,000

$70,959,000

'

'

'

$174,400,000

$104,600,000

$127,500,000

$82,000,000

'

'

$325,600,000

'

$470,510,000

$78,231,000

$483,600,000

$4,700,000

$77,000,000

$8,400,000

$4,000,000

'

'

'

$2,700,000

Percentage of loss reserves covered by reserve study

'

'

93.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unfavorable/(favorable) development during the period

'

'

209,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unfavorable/(favorable) development during the period

'

'

1,219,402,000

873,364,000

'

279,400,000

17,900,000

'

'

'

'

'

'

'

'

1,140,340,000

801,873,000

'

'

'

'

'

39,000,000

22,000,000

51,000,000

'

Worker compensation discount amount

9,300,000

'

9,300,000

'

8,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unamortized reserve for risk premium

19,100,000

'

19,100,000

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortization reserve for risk premium

'

'

$19,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shareholders_Equity_Additional

Shareholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 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	57,427,243	'	57,427,243	'	43,513,678	'	'	'	'	'	14,025,737
Employee stock option exercises	0	0	2,674	0	'	'	'	'	'	'	'
Number of option, grants	'	'	'	'	'	0	13,292	242,626	377,187	'	'
Common stock purchased from employees to pay expected amount of tax liability	'	'	'	'	'	269	6,917	341,867	117,221	'	'
Number of shares, forfeitures	'	'	'	'	'	1,587	6,654	15,602	16,528	'	'
Treasury stock held	9,914	'	9,914	'	9,534,333	'	'	'	'	'	'
Stock repurchase program authorized amount	'	'	$50,000,000	'	'	'	'	'	'	'	'
Stock repurchase program, expiration date	'	'	30-Sep-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	$7,200,000	$26,151,000	$21,874,000	'	'	'	'	'	'	'
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 $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 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	-70,597
Amounts reclassified from accumulated other comprehensive income, net of tax	-21,418
Net current period other comprehensive income	-92,015
Ending Balance	-4,603
Beginning Balance	-5,860
Other comprehensive income before reclassifications, net of tax	-1,026
Amounts reclassified from accumulated other comprehensive income, net of tax	2,522
Net current period other comprehensive income	1,496
Ending Balance	-4,364
Beginning Balance	1,204
Other comprehensive income before reclassifications, net of tax	78
Amounts reclassified from accumulated other comprehensive income, net of tax	'
Net current period other comprehensive income	78
Ending Balance	1,282
Beginning Balance	82,756
Other comprehensive income before reclassifications, net of tax	-71,545
Amounts reclassified from accumulated other comprehensive income, net of tax	-18,896
Net current period other comprehensive income	-90,441
Ending Balance	($7,685)

Reclassified_from_Accumulated_

Reclassified from Accumulated Other Comprehensive Income to Net Income (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Unrealized gains (losses) on available for sale securities, before income tax	$18,751	$1,145	$23,280	$2,297
Unrealized gains (losses) on available for sale securities, net income tax	'	'	-21,418	'
Gains (losses) on cash flow hedges interest rate swaps, net of income taxes	'	'	-2,522	'
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	'	'	-21,418	'
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	'	'	2,522	'
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	'	'	$2,522	'

Borrowings_Detail

Borrowings (Detail) (USD $)	Sep. 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	451,991	449,731
Credit facility	70,000	70,000
Subordinated debentures	163,203	232,678
Total	359,953	454,741
Convertible Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Convertible senior notes	146,933	144,673
Convertible senior notes	$126,750	$152,063

Debt_Additional_Information_De

Debt - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

Sep. 30, 2013

Mar. 31, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Apr. 03, 2013

Dec. 31, 2012

Sep. 30, 2010

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Dec. 13, 2013

Oct. 31, 2010

Oct. 31, 2010

Sep. 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

Interest Rate Swaps

Interest Rate Swaps

Other liability

Other liability

Cash Flow Hedging

Interest Rate Swaps

Interest Rate Swaps

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest expense

$8,008,000

'

$8,224,000

$23,451,000

$24,737,000

'

'

'

$8,900,000

'

'

'

'

'

'

'

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

6,659,000

'

'

6,659,000

'

'

9,016,000

'

'

'

'

'

'

'

6,700,000

9,000,000

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

'

'

'

'

'

'

'

'

'

2,500,000

1,300,000

'

'

'

'

'

Collateral on deposit with the counterparty

6,500,000

'

'

6,500,000

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility agreement, borrowing capacity

'

'

'

'

'

220,000,000

'

'

'

'

'

'

'

'

'

'

Outstanding credit facility amount

70,000,000

'

'

70,000,000

'

'

70,000,000

'

'

'

'

70,000,000

'

'

'

'

Weighted average interest rate

1.94%

'

'

1.94%

'

'

'

'

'

'

'

'

'

'

'

'

Payment of outstanding credit facility amount

'

'

'

'

'

'

'

'

'

'

'

70,000,000

'

'

'

'

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

'

'

'

'

'

'

'

'

28.3299

'

'

'

'

'

'

'

Principal amount of Notes

'

'

'

'

'

'

'

'

1,000

'

'

'

'

'

'

'

Initial conversion price

'

'

'

'

'

'

'

'

$35.30

'

'

'

'

'

'

'

Debt conversion term

'

'

'

'

'

'

'

'

'The adjusted conversion rate at September 30, 2013 is 28.3299 shares of common stock per $1,000 principal amount of the Notes (equivalent to a conversion price of $35.30 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 $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Convertible Senior Notes	'	'
Liability component	'	'
Outstanding principal	$150,000	$150,000
Unamortized OID	-3,067	-5,327
Liability component	146,933	144,673
Equity component, net of tax	$7,469	$7,469

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail)	Sep. 30, 2013	Sep. 30, 2012	Mar. 13, 2013	Sep. 30, 2013	Sep. 30, 2013
			Canopius Group Limited	2008 LTEP	2013 LTIP
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	2,149,118
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		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Restricted Stock	'	'	'	'
Number of Shares	'	'	'	'
Number of Shares, Beginning Balance	'	'	1,015,902	1,120,091
Number of Shares, Granted	0	13,292	242,626	377,187
Number of Shares, Vested	'	'	-954,097	-469,236
Number of Shares, Forfeitures	-1,587	-6,654	-15,602	-16,528
Number of Shares, Ending Balance	288,829	1,011,514	288,829	1,011,514
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	$20.27
Weighted Average Grant Date Fair Value, Vested	'	'	$20.43	$21.10
Weighted Average Grant Date Fair Value, Forfeitures	'	'	$19.14	$20.74
Weighted Average Grant Date Fair Value, Ending Balance	$17.67	$20.38	$17.67	$20.38

Analysis_of_Stock_Option_Activ

Analysis of Stock Option Activity (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Number of Shares	'	'	'	'
Number of Shares Outstanding, Beginning Balance	'	'	969,307	969,315
Number of Shares, Exercised	0	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 $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Weighted average years over which expense will be recognized	'3 years 4 months 24 days	'2 years 4 months 24 days
Restricted Stock	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Expense, net of tax	8,421	4,544
Value of shares vested	21,058	9,045
Value of unvested shares	2,022	18,014
Unrecognized compensation expense	2,022	9,405
Employee Stock Option	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Intrinsic value of outstanding options	'	621
Intrinsic value of vested outstanding options	'	621

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

Sep. 30, 2013

Jun. 30, 2013

Sep. 30, 2012

Jun. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Jun. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Jun. 30, 2013

Jun. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Tower

Tower

Tower

Tower

U.S.

U.S.

U.S.

U.S.

U.S.

Income Tax Expense (Benefit)

Income Tax Expense (Benefit)

Other Comprehensive Income (Loss)

Other Comprehensive Income (Loss)

Non Life Insurance Premiums

Life Insurance and Reinsurance Premiums

Federal

Tower

Tower

Tower

Tower

Tower

Net Operating Loss Carryforwards

Income Taxes [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Income (loss) before income taxes

($342,728,000)

'

$34,961,000

'

($851,153,000)

$41,071,000

'

'

'

'

($358,000,000)

'

($61,300,000)

($867,300,000)

'

'

'

'

'

'

'

'

Deferred tax inventory

'

'

'

'

'

'

'

'

'

'

'

'

'

'

139,200,000

'

'

'

'

'

'

'

Net deferred tax asset

237,900,000

'

'

'

237,900,000

'

245,200,000

'

245,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred tax assets, valuation allowance

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100,900,000

214,800,000

-4,300,000

30,100,000

'

'

'

Prior years unfavorable/(favorable) development

'

'

'

'

469,583,000

70,959,000

'

325,600,000

470,510,000

78,231,000

'

149,700,000

'

'

'

'

'

'

'

'

'

'

Goodwill impairment charge

55,540,000

214,000,000

'

214,000,000

397,211,000

'

57,400,000

214,000,000

271,400,000

'

57,400,000

185,900,000

'

271,400,000,000

'

'

'

'

'

'

'

'

Effective tax rate

-0.40%

'

'

'

0.20%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of excise tax rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.00%

1.00%

'

Excise tax

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$7,400,000

Earnings_Loss_per_Share_Additi

Earnings (Loss) per Share - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 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	190,480	958,980	188,890

Computation_of_Earnings_Per_Sh

Computation of Earnings Per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator	'	'	'	'
Net income (loss) attributable to Tower Group International, Ltd.	($347,634)	$21,629	($842,059)	$23,985
Less: Allocation of income for unvested participating restricted stock	'	-341	'	-52
Less: Dividends on unvested participating restricted stock	-48	-167	-262	-514
Net income (loss) available to common shareholders - Basic	-347,682	21,121	-842,321	23,419
Reallocation of income for unvested participating restricted stock	'	'	'	'
Net income (loss) available to common shareholders - Diluted	($347,682)	$21,121	($842,321)	$23,419
Denominator	'	'	'	'
Basic earnings per share denominator	57,138	42,449	53,338	43,045
Effect of dilutive securities:	'	27	'	85
Diluted earnings per share denominator	57,138	42,476	53,338	43,130
Common stock:	'	'	'	'
Distributed earnings	$0.17	$0.17	$0.50	$0.50
Undistributed earnings	($6.25)	$0.33	($16.29)	$0.04
Total - basic	($6.08)	$0.50	($15.79)	$0.54
Earnings (loss) per share attributable to Tower Group International, Ltd. - Diluted	($6.08)	$0.50	($15.79)	$0.54

Statutory_Financial_Informatio1

Statutory Financial Information - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2013
			Tower Reinsurance, Ltd.	Tower Reinsurance, Ltd.	Subsequent Event
				New Reinsurance Program	Tower Reinsurance, Ltd.
				Agreement
Statutory Accounting Practices [Line Items]	'	'	'	'	'
Amount required to be collateralized against adverse loss reserve development	$215,953,000	$98,581,000	$243,400,000	'	'
Unencumbered liquid assets	$30,300,000	'	$98,600,000	'	$80,900,000
Number of reinsurance treaties commuted	'	'	'	2	'

Business_Segments_Results_Deta

Business Segments Results (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues	'	'	'	'
Premiums earned	$368,293	$430,713	$1,208,543	$1,311,024
Ceding commission revenue	28,195	7,703	54,279	22,946
Policy billing fees	2,796	3,133	9,267	9,267
Total revenues	442,902	474,891	1,379,903	1,447,506
Expenses	'	'	'	'
Loss and loss adjustment expenses	383,778	256,096	1,219,402	873,364
Total expenses	604,274	439,930	1,843,617	1,406,435
Reciprocal Exchanges	'	'	'	'
Revenues	'	'	'	'
Total revenues	47,100	50,200	143,500	149,600
Expenses	'	'	'	'
Total expenses	43,600	45,900	150,500	141,800
Commercial Insurance	'	'	'	'
Expenses	'	'	'	'
Loss and loss adjustment expenses	303,958	171,246	951,245	632,231
Underwriting expenses	136,763	96,966	327,871	292,938
Total expenses	-440,721	268,212	1,279,116	925,169
Underwriting profit (loss)	-216,344	8,187	-547,520	-66,948
Assumed Reinsurance Segment	'	'	'	'
Expenses	'	'	'	'
Loss and loss adjustment expenses	17,216	8,807	64,664	30,469
Underwriting expenses	12,881	9,389	58,070	30,513
Total expenses	30,097	18,196	122,734	60,982
Underwriting profit (loss)	20,908	5,815	23,184	23,499
Personal Insurance	'	'	'	'
Expenses	'	'	'	'
Loss and loss adjustment expenses	62,604	76,043	203,493	210,664
Underwriting expenses	61,196	58,820	182,892	166,437
Total expenses	123,800	134,863	386,385	377,101
Underwriting profit (loss)	4,764	6,276	8,190	23,434
Personal Insurance | Tower	'	'	'	'
Expenses	'	'	'	'
Underwriting profit (loss)	3,132	3,504	19,288	24,717
Personal Insurance | Reciprocal Exchanges	'	'	'	'
Expenses	'	'	'	'
Underwriting profit (loss)	1,632	2,772	-11,098	-1,283
Operating Segments	'	'	'	'
Revenues	'	'	'	'
Total revenues	403,946	441,549	1,272,089	1,343,237
Operating Segments | Commercial Insurance	'	'	'	'
Revenues	'	'	'	'
Premiums earned	201,597	272,595	707,510	847,610
Ceding commission revenue	21,374	2,446	19,888	6,350
Policy billing fees	1,406	1,358	4,198	4,261
Total revenues	224,377	276,399	731,596	858,221
Operating Segments | Assumed Reinsurance Segment	'	'	'	'
Revenues	'	'	'	'
Premiums earned	51,005	24,011	145,918	84,481
Total revenues	51,005	24,011	145,918	84,481
Operating Segments | Personal Insurance	'	'	'	'
Revenues	'	'	'	'
Premiums earned	115,691	134,107	355,115	378,933
Ceding commission revenue	11,483	5,257	34,391	16,596
Policy billing fees	1,390	1,775	5,069	5,006
Total revenues	$128,564	$141,139	$394,575	$400,535

Reconciliation_of_Revenue_by_S

Reconciliation of Revenue by Segment to Consolidated Revenues (Detail) (USD $)	3 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]	'		'	'	'
Net investment income	$25,632		$31,389	$84,351	$97,113
Net realized gains (losses) on investments, including other-than-temporary impairments	18,128		1,145	22,945	4,492
Corporate and other	-4,804	[1]	808	518	2,664
Revenues	442,902		474,891	1,379,903	1,447,506
Operating Segments	'		'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'		'	'	'
Revenues	403,946		441,549	1,272,089	1,343,237
Operating Segments | Commercial Insurance	'		'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'		'	'	'
Revenues	224,377		276,399	731,596	858,221
Operating Segments | Assumed Reinsurance Segment	'		'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'		'	'	'
Revenues	51,005		24,011	145,918	84,481
Operating Segments | Personal Insurance	'		'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'		'	'	'
Revenues	$128,564		$141,139	$394,575	$400,535
[1]	Balance includes $4,662 thousand which relates to the gross-up of ceding commission revenue and commission expense recorded in the statement of operations that relate to the Syndicate 4444 2012 YOA business the Company assumed from Canopius Group and retroceded to an affiliate of Canopius Group. This gross-up is not reflected in the Assumed Re segment revenues as it is not used by management to measure segment profitability or to manage the business. This gross-up has no net effect on income (loss) or segment results.

Reconciliation_of_Revenue_by_S1

Reconciliation of Revenue by Segment to Consolidated Revenues (Parenthetical) (Detail) (USD $)	3 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]	'		'	'	'
Corporate and other	($4,804)	[1]	$808	$518	$2,664
Canopius Group Limited	'		'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'		'	'	'
Corporate and other	$4,662		'	'	'
[1]	Balance includes $4,662 thousand which relates to the gross-up of ceding commission revenue and commission expense recorded in the statement of operations that relate to the Syndicate 4444 2012 YOA business the Company assumed from Canopius Group and retroceded to an affiliate of Canopius Group. This gross-up is not reflected in the Assumed Re segment revenues as it is not used by management to measure segment profitability or to manage the business. This gross-up has no net effect on income (loss) or segment results.

Reconciliation_of_Results_of_I

Reconciliation of Results of Individual Segments to Consolidated Income Before Income Taxes (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Net investment income	$25,632	$31,389	$84,351	$97,113
Net realized gains on investments, including other-than-temporary impairments	18,128	1,145	22,945	4,492
Corporate and other	-893	-6,948	-6,133	-11,121
Acquisition-related transaction costs	-559	-2,679	-20,280	-4,661
Interest expense	-8,008	-8,224	-23,451	-24,737
Goodwill and fixed asset impairment	-183,162	'	-397,211	'
Equity income in unconsolidated affiliate	-3,194	'	4,772	'
Income (loss) before income taxes	-342,728	34,961	-851,153	41,071
Commercial Insurance	'	'	'	'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Underwriting profit (loss)	-216,344	8,187	-547,520	-66,948
Assumed Reinsurance Segment	'	'	'	'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Underwriting profit (loss)	20,908	5,815	23,184	23,499
Personal Insurance	'	'	'	'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Underwriting profit (loss)	$4,764	$6,276	$8,190	$23,434

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)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

1 Months Ended

1 Months Ended

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Aug. 20, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Jan. 03, 2014

Dec. 13, 2013

Nov. 22, 2013

Dec. 31, 2013

Dec. 20, 2013

Dec. 18, 2013

Dec. 13, 2013

Dec. 13, 2013

Dec. 13, 2013

Dec. 13, 2013

Jan. 03, 2014

Jan. 03, 2014

Jan. 03, 2014

Jan. 03, 2014

Dec. 31, 2013

Oct. 31, 2013

USD ($)

USD ($)

USD ($)

Canopius Group Limited

Canopius Group Limited

Assumed Reinsurance Segment

Assumed Reinsurance Segment

Tower Reinsurance, Ltd.

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

2014 Senior Convertible Notes

Canopius Group Limited

Canopius Group Limited

Canopius Group Limited

Canopius Group Limited

Canopius Group Limited

Tower

Tower

Acp Re Ltd

Acp Re Ltd

Tower Reinsurance, Ltd.

Tower Reinsurance, Ltd.

Employee

USD ($)

USD ($)

GBP (£)

Condition One

Condition Two

Maximum

USD ($)

Maximum

USD ($)

USD ($)

GBP (£)

GBP (£)

USD ($)

Subsequent Event [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, par value

$0.01

$0.01

$0.01

'

'

'

'

'

$0.01

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity awards settlement in cash

'

'

'

'

'

'

'

'

$3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding equity awards, aggregate value

'

'

'

'

'

'

'

'

$172,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unearned premium reserve percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

60.00%

'

'

'

'

Commission percentage on premium

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20.00%

'

'

'

'

'

Quota share reinsurance percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

Percentage of common stockholders dissenting to the merger

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15.00%

'

'

'

'

Reimburse transaction expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

'

'

Annual cost savings due to workforce reduction

'

'

'

'

'

'

'

'

'

'

21,000,000

'

'

'

'

'

'

'

'

'

-8,180,000

'

'

'

President and Chief Executive Officer of Tower,who beneficially owns percentage of issued and outstanding common stock

'

'

'

'

'

'

'

'

4.20%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt carrying amount

'

'

'

'

'

'

'

'

'

'

'

'

146,900,000

'

'

'

'

'

'

'

'

'

'

'

Debt instrument interest rate

'

'

'

'

'

'

'

'

'

'

'

'

5.00%

'

'

'

'

'

'

'

'

'

'

'

Net written premiums

237,600,000

1,093,400,000

'

'

'

237,600,000

1,093,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Additional collateral requested

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

26,300,000

Unencumbered liquid assets

30,300,000

30,300,000

'

'

'

'

'

98,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

80,900,000

'

Initial purchase price

'

'

'

26,485,000

74,900,000

'

'

'

'

'

'

'

'

'

69,700,000

42,500,000

40,600,000

1,950,000

'

'

'

'

'

'

Sale of investment to NKSJ Holdings, percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

Repayment of Outstanding credit facility led by Bank of America

'

'

'

'

'

'

'

'

'

70,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of workforce reduction

'

'

'

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Total number of employees to be affected by workforce reduction

'

'

'

'

'

'

'

'

'

'

1,400

'

'

'

'

'

'

'

'

'

'

'

'

'

Recognized pre-tax charges for severance and other one-time termination benefits and other associated costs

'

'

'

'

'

'

'

'

'

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$5,000,000

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