Navigators (NAVG) 10-Q 9 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 27, 2014
Document Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'NAVG	'
Entity Registrant Name	'NAVIGATORS GROUP INC	'
Entity Central Index Key	'0000793547	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	14,256,214

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments and cash:	'	'
Fixed maturities, available-for-sale, at fair value (amortized cost: 2014, $2,133,492; 2013, $2,036,999)	$2,162,713	$2,047,873
Equity securities, available-for-sale, at fair value (cost: 2014, $137,358; 2013, $118,804)	163,527	143,954
Short-term investments, at cost which approximates fair value	207,843	296,250
Cash	55,041	86,509
Total investments and cash	2,589,124	2,574,586
Premiums receivable	416,675	325,025
Prepaid reinsurance premiums	246,545	247,822
Reinsurance recoverable on paid losses	42,260	38,384
Reinsurance recoverable on unpaid losses and loss adjustment expenses	830,431	822,438
Deferred policy acquisition costs	79,334	67,007
Accrued investment income	14,221	13,866
Goodwill and other intangible assets	7,174	7,177
Current income tax receivable, net	3,204	9,918
Deferred income tax, net	20,928	28,187
Receivable for investments sold	10,078	3
Other assets	39,831	35,039
Total assets	4,299,805	4,169,452
Liabilities:	'	'
Reserves for losses and loss adjustment expenses	2,087,471	2,045,071
Unearned premiums	798,745	714,606
Reinsurance balances payable	145,948	167,252
Senior Notes	263,340	263,308
Payable for investments purchased	10,231	7,624
Accounts payable and other liabilities	57,236	69,379
Total liabilities	3,362,971	3,267,240
Stockholders' equity:	'	'
Preferred stock, $.10 par value, authorized 1,000,000 shares, none issued	'	'
Common stock, $.10 par value, authorized 50,000,000 shares, issued 17,766,586 shares for 2014 and 17,709,876 shares for 2013	1,776	1,770
Additional paid-in capital	337,242	335,546
Treasury stock, at cost (3,511,380 shares for 2014 and 2013)	-155,801	-155,801
Retained earnings	720,305	692,337
Accumulated other comprehensive income	33,312	28,360
Total stockholders' equity	936,834	902,212
Total liabilities and stockholders' equity	$4,299,805	$4,169,452

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Fixed maturities, available-for-sale, amortized cost	$2,133,492	$2,036,999
Equity securities, available-for-sale, cost	$137,358	$118,804
Preferred stock, par value	$0.10	$0.10
Preferred stock, authorized shares	1,000,000	1,000,000
Preferred stock, issued shares	'	'
Common stock, par value	$0.10	$0.10
Common stock, authorized shares	50,000,000	50,000,000
Common stock, issued shares	17,766,586	17,709,876
Treasury stock, shares	3,511,380	3,511,380

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Gross written premiums	$422,790	$393,222
Revenues:	'	'
Net written premiums	311,850	269,452
Change in unearned premiums	-86,578	-67,124
Net earned premiums	225,272	202,328
Net investment income	16,610	13,657
Total other-than-temporary impairment losses	'	-42
Portion of loss recognized in other comprehensive income (before tax)	'	'
Net other-than-temporary impairment losses recognized in earnings	'	-42
Net realized gains (losses)	833	4,814
Other income (expense)	10,399	618
Total revenues	253,114	221,375
Expenses:	'	'
Net losses and loss adjustment expenses	135,067	131,342
Commission expenses	25,727	26,555
Other operating expenses	47,146	40,874
Interest expense	3,852	2,051
Total expenses	211,792	200,822
Income (loss) before income taxes	41,322	20,553
Income tax expense (benefit)	13,354	6,643
Net income	$27,968	$13,910
Net income per common share:	'	'
Basic	$1.96	$0.99
Diluted	$1.94	$0.97
Average common shares outstanding:	'	'
Basic	14,233,504	14,085,821
Diluted	14,408,416	14,374,957

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Net income	$27,968	$13,910
Change in net unrealized gains (losses) on investments:	'	'
Unrealized gains (losses) on investments arising during the period, net of tax of $7,010 and $617 in 2014 and 2013, respectively	13,314	1,145
Reclassification adjustment for net realized (gains) losses included in net income net of tax of $366 and $1,770 in 2014 and 2013, respectively	-679	-3,179
Change in net unrealized gains (losses) on investments	12,635	-2,034
Change in other-than-temporary impairments:	'	'
Non credit other-than-temporary impairments arising during the period, net of tax of $31 and $150 in 2014 and 2013, respectively	56	279
Reclassification adjustment for non credit other-than-temporary impairment losses recognized in net income	'	'
Change in other-than-temporary impairments	56	279
Change in foreign currency translation gains (losses), net of tax of $3,584 and $1,543 in 2014 and 2013, respectively	-7,739	2,630
Other comprehensive income	4,952	875
Comprehensive income	$32,920	$14,785

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Unrealized gains (losses) on investments arising during the period, tax	$7,010	$617
Reclassification adjustment for net realized (gains) losses included in net income, tax	366	1,770
Non credit other-than-temporary impairments arising during the period, tax	31	150
Change in foreign currency translation gains (losses), tax	$3,584	$1,543

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
In Thousands, except Share data, unless otherwise specified
Beginning balance at Dec. 31, 2013	$902,212	$1,770	$335,546	($155,801)	$692,337	$28,360
Beginning balance (in shares) at Dec. 31, 2013	'	17,709,876	'	3,511,380	'	'
Net income	27,968	'	'	'	27,968	'
Changes in other comprehensive income:	'	'	'	'	'	'
Change in net unrealized gain (loss) on investments	12,635	'	'	'	'	12,635
Change in net non-credit other-than-temporary impairment losses	56	'	'	'	'	56
Change in foreign currency translation gain (loss)	-7,739	'	'	'	'	-7,739
Total other comprehensive income	4,952	'	'	'	'	4,952
Shares issued under stock plan (in shares)	'	56,710	'	'	'	'
Shares issued under stock plan	-184	6	-190	'	'	'
Share-based compensation	1,886	'	1,886	'	'	'
Ending balance at Mar. 31, 2014	$936,834	$1,776	$337,242	($155,801)	$720,305	$33,312
Ending balance (in shares) at Mar. 31, 2014	'	17,766,586	'	3,511,380	'	'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activities:	'	'
Net income	$27,968	$13,910
Adjustments to reconcile net income to net cash provided by (used in) operating activities:	'	'
Depreciation & amortization	1,184	1,025
Deferred income taxes	-106	-1,370
Net realized (gains) losses	-833	-4,814
Net other-than-temporary losses recognized in earnings	'	42
Changes in assets and liabilities:	'	'
Reinsurance recoverable on paid and unpaid losses and loss adjustment expenses	-11,869	5,176
Reserves for losses and loss adjustment expenses	42,400	7,338
Prepaid reinsurance premiums	2,051	-11,761
Unearned premiums	86,063	76,976
Premiums receivable	-91,650	-80,215
Deferred policy acquisition costs	-12,327	-8,344
Accrued investment income	-355	-1,053
Reinsurance balances payable	-22,476	-700
Current income tax receivable, net	6,714	4,945
Other	-17,922	3,157
Net cash provided by (used in) operating activities	8,842	4,312
Fixed maturities	'	'
Redemptions and maturities	50,542	28,469
Sales	107,681	362,090
Purchases	-259,494	-358,829
Equity securities	'	'
Sales	7,935	4,787
Purchases	-25,473	-9,926
Change in payable for securities	-7,469	-42,464
Net change in short-term investments	88,353	24,234
Purchase of property and equipment	-2,991	-919
Net cash provided by (used in) investing activities	-40,916	7,442
Financing activities:	'	'
Proceeds of stock issued from employee stock purchase plan	453	374
Proceeds of stock issued from exercise of stock options	153	1,112
Net cash provided by (used in) financing activities	606	1,486
Increase (decrease) in cash	-31,468	13,240
Cash at beginning of year	86,509	45,336
Cash at end of period	55,041	58,576
Supplemental cash information:	'	'
Income taxes paid, net	3,628	1,198
Interest paid	'	'
Issuance of stock to directors	$438	$400

Organization_Summary_of_Signif

Organization & Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Organization & Summary of Significant Accounting Policies	'
	Note 1. Organization & Summary of Significant Accounting Policies
	The accompanying interim consolidated financial statements are unaudited and reflect all adjustments which, in the opinion of management, are necessary to fairly present the results of The Navigators Group, Inc. and its subsidiaries for the interim periods presented on the basis of United States generally accepted accounting principles (“GAAP” or “U.S. GAAP”). All such adjustments are of a normal recurring nature. All significant intercompany transactions and balances have been eliminated. The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported revenues and expenses during the reporting periods. The results of operations for any interim period are not necessarily indicative of results for the full year. The term “the Company” as used herein is used to mean The Navigators Group, Inc. and its subsidiaries, unless the context otherwise requires. The terms “Parent” or “Parent Company” are used to mean The Navigators Group, Inc. without its subsidiaries. These financial statements should be read in conjunction with the consolidated financial statements and notes contained in the Company’s 2013 Annual Report on Form 10-K. Certain amounts for the prior year have been reclassified to conform to the current year’s presentation.
	We are an international insurance and reinsurance company focusing on specialty products within the overall property and casualty market. Our largest product line and most long-standing area of specialization is ocean marine insurance. We have also developed other specialty insurance and reinsurance lines within our property casualty business, such as commercial primary and excess liability as well as specialty niches in professional liability.
	Our revenue is primarily comprised of premiums and investment income. We derive our premiums primarily from business written by wholly-owned underwriting management companies which produce, manage, and service insurance and reinsurance business. Our products are distributed through multiple channels, utilizing global, national and regional retail and wholesale insurance brokers.
	Navigators Management Company (“NMC”) and Navigators Management (UK) Limited (“NMUKL”) produce, manage, and service insurance and reinsurance for Navigators Insurance Company (“NIC”), which includes a United Kingdom Branch (“U.K. Branch”), and Navigators Specialty Insurance Company (“NSIC”), which underwrites specialty and professional liability insurance on an excess and surplus lines basis. All of the insurance business written by NSIC is fully reinsured by NIC pursuant to a 100% quota share reinsurance agreement.
	Navigators Underwriting Agency Ltd. (“NUAL”), a Lloyd’s of London (“Lloyd’s”) underwriting agency manages Lloyd’s Syndicate 1221 (“Syndicate 1221”). Through our participation of Syndicate 1221, we primarily underwrite marine and related lines of business along with offshore energy, construction coverage for onshore energy businesses, specialty assumed reinsurance, and professional liability insurance. We have controlled 100% of Syndicate 1221’s stamp capacity for the 2014, 2013, and 2012 underwriting years through our wholly-owned subsidiary, Navigators Corporate Underwriters Ltd. (“NCUL”), which is referred to as a corporate name in the Lloyd’s market. In addition, we have also established underwriting agencies in Antwerp, Belgium, Stockholm, Sweden, and Copenhagen, Denmark, which underwrite risks pursuant to binding authorities with NUAL into Syndicate 1221.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2014
Segment Information	'
	Note 2. Segment Information
	The Company classifies its business into two underwriting segments consisting of the Insurance Companies segment (“Insurance Companies”) and the Lloyd’s Operations segment (“Lloyd’s Operations”), which are separately managed by division and aggregated in to each underwriting segment, and a Corporate segment (“Corporate”). Segment data for each of the two underwriting segments include allocations of the operating expenses of the wholly-owned underwriting management companies and the Parent Company’s operating expenses and related income tax amounts. The Corporate segment consists of the Parent Company’s investment income, interest expense and the related tax effect.
	The Insurance Companies consist of NIC, including its U.K. Branch, and its wholly-owned subsidiary, NSIC. They are primarily engaged in underwriting marine insurance and related lines of business, specialty insurance lines of business, including contractors general liability insurance, commercial umbrella and primary and excess casualty businesses, specialty assumed reinsurance business, and professional liability insurance. NSIC underwrites specialty and professional liability insurance on an excess and surplus lines basis.
	The Lloyd’s Operations primarily underwrite marine and related lines of business along with offshore energy, construction coverages for onshore energy business, specialty assumed reinsurance, and professional liability insurance at Lloyd’s through Syndicate 1221.
	The Company evaluates the performance of each underwriting segment based on its underwriting and GAAP results. Underwriting results are measured based on underwriting profit or loss and the related combined ratio, which are both non-GAAP measures of underwriting profitability. Underwriting profit or loss is calculated from net earned premiums, less the sum of net losses and loss adjustment expenses (“LAE”), commission expenses, other operating expenses and other underwriting income (expense). The combined ratio is derived by dividing the sum of net losses and LAE, commission expenses, other operating expenses and other underwriting income (expense) by net earned premiums. A combined ratio of less than 100% indicates an underwriting profit and greater than 100% indicates an underwriting loss. Each segment maintains its own investments on which it earns income and realizes capital gains or losses. The Company’s underwriting performance is evaluated separately from the performance of its investment portfolios.
	Financial data by segment for the three months ended March 31, 2014 and 2013 were as follows:
		Three Month Ended March 31, 2014
	In thousands	Insurance			Lloyd’s			Corporate (1)			Total
		Companies			Operations
	Gross written premiums	$	311,798		$	110,992		$	—		$	422,790
	Net written premiums		233,951			77,899			—			311,850
	Net earned premiums		165,884			59,388			—			225,272
	Net losses and loss adjustment expenses		(106,427	)		(28,640	)		—			(135,067	)
	Commission expenses		(16,710	)		(9,526	)		509			(25,727	)
	Other operating expenses		(33,361	)		(13,785	)		—			(47,146	)
	Other underwriting income (expense)		658			6			(509	)		155
	Underwriting profit (loss)	$	10,044		$	7,443		$	—		$	17,487
	Net investment income		14,777			1,815			18			16,610
	Net realized gains (losses)		1,237			(404	)		—			833
	Interest expense		—			—			(3,852	)		(3,852	)
	Other income		49			10,195			—			10,244
	Income (loss) before income taxes	$	26,107		$	19,049		$	(3,834	)	$	41,322
	Income tax expense (benefit)		8,112			6,638			(1,396	)		13,354
	Net income (loss)	$	17,995		$	12,411		$	(2,438	)	$	27,968
	Identifiable assets	$	3,203,763		$	941,426		$	154,616		$	4,299,805
	Losses and loss adjustment expenses ratio		64.2	%		48.2	%					60	%
	Commission expense ratio		10.1	%		16	%					11.4	%
	Other operating expense ratio (2)		19.6	%		23.3	%					20.8	%
	Combined ratio		93.9	%		87.5	%					92.2	%
	(1) - Includes Corporate segment intercompany eliminations.
	(2) - Includes Other operating expenses and Other underwriting income.
		Three Month Ended March 31, 2013
	In thousands	Insurance			Lloyd’s			Corporate (1)			Total
		Companies			Operations
	Gross written premiums	$	301,628		$	91,594		$	—		$	393,222
	Net written premiums		216,319			53,133			—			269,452
	Net earned premiums		154,331			47,997			—			202,328
	Net losses and loss adjustment expenses		(106,985	)		(24,357	)		—			(131,342	)
	Commission expenses		(18,517	)		(8,621	)		583			(26,555	)
	Other operating expenses		(29,343	)		(11,531	)		—			(40,874	)
	Other income (expense)		659			542			(583	)		618
	Underwriting profit (loss)	$	145		$	4,030		$	—		$	4,175
	Net investment income		11,951			1,702			4			13,657
	Net realized gains (losses)		4,792			(20	)		—			4,772
	Interest expense		—			—			(2,051	)		(2,051	)
	Income (loss) before income taxes	$	16,888		$	5,712		$	(2,047	)	$	20,553
	Income tax expense (benefit)		5,404			2,046			(807	)		6,643
	Net income (loss)	$	11,484		$	3,666		$	(1,240	)	$	13,910
	Identifiable assets	$	3,087,308		$	936,471		$	47,266		$	4,071,045
	Losses and loss adjustment expenses ratio		69.3	%		50.7	%					64.9	%
	Commission expense ratio		12	%		18	%					13.1	%
	Other operating expense ratio (2)		18.6	%		22.9	%					19.9	%
	Combined ratio		99.9	%		91.6	%					97.9	%
	(1) - Includes Corporate segment intercompany eliminations.
	(2) - Includes Other operating expenses and Other income.
	The following tables provide additional financial data by segment for the three months ended March 31, 2014 and 2013:
	In thousands
	Gross Written Premiums:	Three Months
	Insurance Companies:	2014			2013
	Marine	$	52,233		$	50,847
	Property Casualty		229,356			218,964
	Professional Liability		30,209			31,817
			311,798			301,628
Lloyd’s Operations:
Marine		62,957			53,644
Property Casualty		33,079			25,058
Professional Liability		14,956			12,892
		110,992			91,594
Total	$	422,790		$	393,222
Net Written Premiums:	Three Months
Insurance Companies:	2014			2013
Marine	$	41,124		$	41,141
Property Casualty		172,361			149,951
Professional Liability		20,466			25,227
		233,951			216,319
Lloyd’s Operations:
Marine		52,131			39,558
Property Casualty		16,534			7,312
Professional Liability		9,234			6,263
		77,899			53,133
Total	$	311,850		$	269,452
Net Earned Premiums:	Three Months
Insurance Companies:	2014			2013
Marine	$	32,760		$	36,725
Property Casualty		110,826			92,718
Professional Liability		22,298			24,888
		165,884			154,331
Lloyd’s Operations:
Marine		38,887			34,045
Property Casualty		12,958			7,879
Professional Liability		7,543			6,073
		59,388			47,997
Total	$	225,272		$	202,328
The Insurance Companies net earned premiums include $11.6 million and $10.1 million of net earned premiums from the U.K. Branch for the three months ended March 31, 2014 and 2013, respectively.

Reinsurance_Ceded

Reinsurance Ceded	3 Months Ended
	Mar. 31, 2014
Reinsurance Ceded	'
	Note 3. Reinsurance Ceded
	The Company’s ceded earned premiums were $113.6 million and $110.9 million for the three months ended March 31, 2014 and 2013, respectively. The Company’s ceded incurred losses were $53.9 million and $53.6 million for the three months ended March 31, 2014 and 2013, respectively.
	The following table lists the Company’s 20 largest reinsurers measured by the amount of reinsurance recoverable for ceded losses and LAE and ceded unearned premium (constituting 76.2% of the total recoverable), together with the reinsurance recoverable and collateral as of March 31, 2014, and the reinsurers’ ratings from A.M. Best Company (“A.M. Best”) or Standard & Poor’s (“S&P”):
		Reinsurance Recoverables
	In thousands	Unearned		Paid/Unpaid		Total (1)		Collateral		A.M. Best	S&P
		Premium		Losses				Held (2)
	National Indemnity Company	$	50,635	$	101,575	$	152,210	$	30,795	A++	AA+
	Transatlantic Reinsurance Company		19,819		75,865		95,684		6,984	A	A+
	Everest Reinsurance Company		21,782		70,793		92,575		7,706	A+	A+
	Munich Reinsurance America Inc.		5,505		68,798		74,303		4,510	A+	AA-
	Swiss Reinsurance America Corporation		7,690		63,942		71,632		4,759	A+	AA-
	Lloyd’s Syndicate #2003		6,704		40,585		47,289		5,977	A	A+
	Allied World Reinsurance		13,380		33,043		46,423		3,129	A	A
	Partner Reinsurance Europe		9,483		29,208		38,691		16,623	A+	A+
	Scor Global P&C SE		9,690		22,199		31,889		6,724	A	A+
	Employers Mutual Casualty Company		11,368		14,766		26,134		10,689	A	NR
	Atlantic Specialty Insurance		6,741		15,944		22,685		839	A	A-
	Tower Insurance Company		—		21,738		21,738		1,803	B	NR
	QBE Reinsurance Corp		6,666		12,827		19,493		1,043	A	A+
	Ace Property and Casualty Insurance Company		10,108		7,884		17,992		4,152	A++	AA-
	Validus Reinsurance Ltd.		2,316		15,198		17,514		12,140	A	A
	Ironshore Indemnity Inc.		7,224		10,248		17,472		9,273	A	NR
	Lloyd’s Syndicate #4000		96		16,127		16,223		111	A	A+
	Odyssey American Reinsurance Corporation		3,420		12,425		15,845		1,545	A	A-
	Berkley Insurance Company		2,096		11,846		13,942		—	A+	A+
	AXIS Re Europe		4,108		9,453		13,561		3,724	A+	A+
	Top 20 Reinsurers	$	198,831	$	654,464	$	853,295	$	132,526
	Others		47,714		218,227		265,941		72,914
	Total	$	246,545	$	872,691	$	1,119,236	$	205,440
	(1) - Net of reserve for uncollectible reinsurance of approximately $11.3 million.
	(2) - Collateral of $205.4 million consists of $145.9 million in ceded balances payable, $53.4 million in letters of credit, and $6.1 million of other balances held by the Company’s Insurance Companies and Lloyd’s Operations.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2014
Stock-Based Compensation	'
	Note 4. Stock-Based Compensation
	Stock-based compensation granted under the Company’s stock plans is expensed in tranches over the vesting period. Options and non-performance based grants generally vest equally over a three or four year period and the options have a maximum term of ten years. Certain non-performance based grants vest over five years with one-third vesting in each of the third, fourth and fifth years. The Company’s performance based share grants generally consist of three types of awards. The restricted stock units issued in 2014 and after will cliff vest on the third anniversary of the date of the grant with 100% dependent on the rate of cumulative annual growth in tangible book value for the three years immediately prior to the vesting date, with actual shares that vest ranging between 150% to 50% of that portion of the original award. The restricted stock units issued between 2011 - 2013 will cliff vest on the third anniversary of the date of grant, with 50% vesting in full, and 50% dependent on the rate of compound annual growth in book value per share for the three years immediately prior to the vesting date, with actual shares that vest ranging between 150% to 0% of that portion of the original award. Those performance based restricted stock units issued prior to 2011 generally vest over five years with one-third vesting in each of the third, fourth and fifth years, with 100% dependent on the rolling three-year average return on equity based on the three years prior to the year in which the vesting occurs, with actual shares that vest ranging between 150% to 0% of the original award.
	The amounts charged to expense for stock-based compensation for the three months ended March 31, 2014 and 2013 are presented in the following table:
			Three Months Ended March 31,
	In thousands		2014		2013
	Restricted stock units		$	1,886	$	1,358
	Directors restricted stock grants(1)			100		100
	Employee stock purchase plan			74		9
	Total stock based compensation		$	2,060	$	1,467
	(1) -	Relates to non-employee directors serving on the Parent Company’s Board of Directors, all of whom have been elected by the Company’s stockholders, as well as non-employee directors serving on NUAL’s Board of Directors.

Lloyds_Syndicate_1221

Lloyd's Syndicate 1221	3 Months Ended
	Mar. 31, 2014
Lloyd's Syndicate 1221	'
	Note 5. Lloyd’s Syndicate 1221
	The Company’s Lloyd’s Operations included in the consolidated financial statements represents its participation in Syndicate 1221. Syndicate 1221’s stamp capacity is £215 million ($359.1 million) for the 2014 underwriting year compared to £195 million ($323.7 million) for the 2013 underwriting year. Stamp capacity is a measure of the amount of premiums a Lloyd’s syndicate is authorized to write based on a business plan approved by the Council of Lloyd’s. Syndicate 1221’s stamp capacity is expressed net of commission (as is standard at Lloyd’s). The Syndicate 1221 premiums recorded in the Company’s financial statements are gross of commission. The Company controlled 100% of Syndicate 1221’s stamp capacity for the 2014 and 2013 underwriting years through its wholly-owned Lloyd’s corporate member.
	During the quarter, the Syndicate revised its foreign exchange accounting methodology from reporting the Syndicate’s financial position and results using three functional currencies (GBP, USD and CAD) to one functional currency (USD). The USD was chosen as the single functional currency as the majority of the Syndicate’s insurance business has been and continues to be transacted in USD. This cumulative change in re-measurement has resulted in an immaterial correction of $10.0 million ($6.6 million, after-tax) reducing Accumulated Other Comprehensive Income in the consolidated balance sheet, offset by a gain in Other Income in the consolidated statement of income. The impact of the correction is not material to the previously issued interim and annual financial statements for 2013 and 2012.
	The Company provides letters of credit and posts cash to Lloyd’s to support its participation in Syndicate 1221’s stamp capacity. As of March 31, 2014, the Company had provided letters of credit of $152.1 million and has $1.0 million of cash collateral posted. If Syndicate 1221 increases its stamp capacity and the Company participates in the additional stamp capacity, or if Lloyd’s changes the capital requirements, the Company may be required to supply additional collateral acceptable to Lloyd’s. If the Company is unwilling or unable to provide additional acceptable collateral, the Company will be required to reduce its participation in the stamp capacity of Syndicate 1221. The letters of credit are provided through a credit facility with a consortium of banks which provides the Company with the ability to have letters of credit issued to support Syndicate 1221’s stamp capacity at Lloyd’s for the 2013 and 2014 underwriting years, as well as open prior years. If any letters of credit remain outstanding under the facility after December 31, 2014, we would be required to post additional collateral to secure the remaining letters of credit. If the credit facility is not renewed prior to December 31, 2014, the Company will need to find internal and/or external sources to provide either letters of credit or other collateral in order to continue to participate in Syndicate 1221. The credit facility is collateralized by all of the common stock of NIC. Refer to Note 10, Credit Facility, for additional information.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Taxes	'
	Note 6. Income Taxes
	The Company is subject to the tax laws and regulations of the United States (“U.S.”) and the foreign countries in which it operates. The Company files a consolidated U.S. Federal tax return, which includes all domestic subsidiaries and the United Kingdom (“U.K.”) Branch. The income from the foreign operations is designated as either U.S. connected income or non-U.S. connected income. Lloyd’s is required to pay U.S. income tax on U.S. connected income written by Lloyd’s syndicates. Lloyd’s and the Internal Revenue Service (“IRS”) have entered into an agreement whereby the amount of tax due on U.S. connected income is calculated by Lloyd’s and remitted directly to the IRS. These amounts are then charged to the corporate member in proportion to its participation in the relevant syndicates. The Company’s corporate member is subject to this agreement and receives U.K. tax credits in the U.K. for any U.S. income tax incurred up to the U.K. income tax charged on the U.S. connected income. The non-U.S. connected insurance income would generally constitute taxable income under the Subpart F income section of the U.S. Internal Revenue Code (“Subpart F”) since less than 50% of Syndicate 1221’s premiums are derived within the U.K. and would therefore be subject to U.S. taxation when the Lloyd’s year of account closes. Taxes are accrued at a 35% rate on the Company’s foreign source insurance income and foreign tax credits, where available, are utilized to offset U.S. tax as permitted. The Company’s effective tax rate for Syndicate 1221 taxable income could substantially exceed 35% to the extent the Company is unable to offset U.S. taxes paid under Subpart F tax regulations with U.K. tax credits on future underwriting year distributions. U.S. taxes were not accrued on the earnings of the Company’s foreign agencies in previous years as these earnings were subject to the active financing exception and were not includable as Subpart F income. Certain provisions of Subpart F expired for years after December 31, 2013, therefore, these earnings will be taxable in the U.S. at the 35% tax rate beginning January 1, 2014. The impact of this change is immaterial for the period ended March 31, 2014.
	The Company has not provided for U.S. income taxes on approximately $21.4 million of undistributed earnings of its non-U.S. subsidiaries since it is intended that those earnings will be reinvested indefinitely in those subsidiaries. If a future determination is made that those earnings no longer are intended to be reinvested indefinitely in those subsidiaries, U.S. income taxes of approximately $2.2 million, assuming all foreign tax credits are realized, would be included in the tax provision at that time and would be payable if those earnings were distributed to the Company.
	Unrecognized tax benefits are differences between tax positions taken in the tax returns and benefits recognized in the financial statements. The Company has no unrecognized tax benefits as of March 31, 2014 and 2013. The Company did not incur any interest or penalties related to unrecognized tax benefits for the three months ended March 31, 2014 and 2013. The Company currently is under examination by the Internal Revenue Service for taxable years 2010 and 2011 and generally is subject to U.S. Federal, state or local or foreign tax examinations by tax authorities for 2009 and subsequent years.
	The Company recorded income tax expense of $13.4 million for the three months ended March 31, 2014 compared to $6.6 million for the same period in 2013, resulting in an effective tax rate of 32.3% for the three months ended March 31, 2014 and 2013.
	The Company had state and local deferred tax assets amounting to potential future tax benefits of $0.4 million and $0.6 million as of March 31, 2014 and December 31, 2013, respectively. Included in the deferred tax assets are state and local net operating loss carry-forwards of $0.1 million as of March 31, 2014 and December 31, 2013. A valuation allowance was established for the full amount of these potential future tax benefits due to the uncertainty associated with their realization. The Company’s state and local tax carry-forwards as of March 31, 2014 expire from 2024 to 2032.

Senior_Notes_due_May_1_2016

Senior Notes due May 1, 2016	3 Months Ended
	Mar. 31, 2014
Senior Notes due May 1, 2016	'
	Note 7. Senior Notes due May 1, 2016
	On October 4, 2013, the Company completed a public debt offering of $265 million principal amount of 5.75% Senior Notes (“5.75% Senior Notes”) and received net proceeds of $263 million. The principal amount of the Senior Notes is payable in one single installment on October 15, 2023. The Company used a portion of the proceeds of the 5.75% Senior Notes for the redemption of the 7.0% Senior Notes due May 1, 2016 (“7.0% Senior Notes”). The Company incurred a charge of $17.9 million for the payment of call premium in connection with the redemption of the 7.0% Senior Notes. The 5.75% Senior Notes liability as of March 31, 2014 was $263.3 million. The unamortized discount as of March 31, 2014 was $1.7 million.
	The fair value of the 5.75% Senior Notes as of March 31, 2014 was $286.7 million. The fair value was determined using quoted prices for similar instruments in active markets and is classified as Level 2 within the fair value hierarchy as defined by the accounting guidance for fair value measurements.
	Interest is payable on the 5.75% Senior Notes each April 15 and October 15. The effective interest rate related to the 5.75% Senior Notes, based on the proceeds net of discount and all issuance costs, is approximately 5.86%. Interest expense on the 5.75% Senior Notes totaled $3.9 million for the three months ended March 31, 2014. Interest expense on the 7.0% Senior Notes was approximately $2 million for the three months ended March 31, 2013.
	The interest rate payable on the 5.75% Senior Notes is subject to a tiered adjustment based on defined changes in the Company’s debt ratings. The Company may redeem the 5.75% Senior Notes in whole at any time or in part from time to time at a make-whole redemption price. The 5.75% Senior Notes are the Company’s only senior unsecured obligation and will rank equally with future senior unsecured indebtedness.
	The terms of the 5.75% Senior Notes contain various restrictive business and financial covenants, including a restriction on indebtedness, and other restrictions typical for debt obligations of this type, including limitations on mergers, liens and dispositions of the common stock of certain subsidiaries. As of March 31, 2014, the Company was in compliance with all such covenants.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies	'
	Note 8. Commitments and Contingencies
	The State of Connecticut (“the State”) awarded the Company up to $11.5 million ($8.0 million in loans and $3.5 million in grants) as an incentive to move its corporate headquarters to Stamford, Connecticut. The loan is non-interest bearing, has a term of 10 years and is subject to forgiveness under conditions of the agreement with the State. The amount of the assistance to be received is dependent on the Company reaching certain milestones for creation of new jobs over a five-year period, and the funds are to be used to offset certain equipment purchases, facility costs, training of employees and other eligible project-related costs. The Company completed the move to Stamford in September 2013 and received $7.5 million for reaching the first job milestone. Earning of the grant and forgiveness of the loan is subject to certain conditions, including maintaining the required jobs for an extended period of time. As of March 31, 2014, the length of time commitment has not been met. However, the Company expects to meet all the conditions to keep the amount of assistance received to date, and accordingly, is recognizing the assistance received over the period in which the Company recognizes the expenses for which the assistance is intended to compensate as a reduction of such expenses. The Company recognized $0.3 million of the assistance for the three months ended March 31, 2014, and as of March 31, 2014 and December 31, 2013, has deferred revenue of $6.9 million and $7.2 million, respectively, which is included in other liabilities.
	In the ordinary course of conducting business, the Company’s subsidiaries are involved in various legal proceedings, either indirectly as insurers for parties or directly as defendants. Most of these proceedings consist of claims litigation involving the Company’s subsidiaries as either (a) liability insurers defending or providing indemnity for third party claims brought against insureds or (b) insurers defending first party coverage claims brought against them. The Company accounts for such activity through the establishment of unpaid loss and loss adjustment reserves. The Company’s management believes that the ultimate liability, if any, with respect to such ordinary-course claims litigation, after consideration of provisions made for potential losses and cost of defense, will not be material to the Company’s consolidated financial condition, results of operations, or cash flows.
	The Company’s subsidiaries are also from time to time involved with other legal actions, some of which assert claims for substantial amounts. These actions include claims asserting extra contractual obligations, such as claims involving allegations of bad faith in the handling of claims or the underwriting of policies. In general, the Company believes it has valid defenses to these cases. The Company’s management expects that the ultimate liability, if any, with respect to future extra-contractual matters will not be material to its consolidated financial position. Nonetheless, given the large or indeterminate amounts sought in certain of these matters, and the inherent unpredictability of litigation, an adverse outcome in such matters could, from time to time, have a material adverse outcome on the Company’s consolidated results of operations or cash flows in a particular fiscal quarter or year.

Investments

Investments	3 Months Ended
	Mar. 31, 2014
Investments	'
	Note 9. Investments
	The following tables set forth the Company’s cash and investments as of March 31, 2014 and December 31, 2013. The table below includes other-than-temporarily impaired (“OTTI”) securities recognized within accumulated other comprehensive income (“AOCI”).
		March 31, 2014
						Gross				Gross			Cost or
		Fair				Unrealized				Unrealized			Amortized
	In thousands	Value				Gains				(Losses)			Cost
	Fixed maturities:
	U.S. Treasury bonds, agency bonds and foreign government bonds	$	417,942			$	3,066			$	(4,956	)	$	419,832
	States, municipalities and political subdivisions		491,598				12,216				(6,948	)		486,330
	Mortgage-backed and asset-backed securities:
	Agency mortgage-backed securities		265,818				7,182				(3,525	)		262,161
	Residential mortgage obligations		57,852				1,573				(136	)		56,415
	Asset-backed securities		162,226				639				(563	)		162,150
	Commercial mortgage-backed securities		173,333				7,792				(272	)		165,813
	Subtotal	$	659,229			$	17,186			$	(4,496	)	$	646,539
	Corporate bonds		593,944				15,472				(2,319	)		580,791
	Total fixed maturities	$	2,162,713			$	47,940			$	(18,719	)	$	2,133,492
	Equity securities - common stocks		141,476				26,589				(1,271	)		116,158
	Equity securities - Preferred stocks		22,051				852				(1	)		21,200
	Short-term investments		207,843				—				—			207,843
	Cash		55,041				—				—			55,041
	Total	$	2,589,124			$	75,381			$	(19,991	)	$	2,533,734
		December 31, 2013
						Gross				Gross			Cost or
		Fair				Unrealized				Unrealized			Amortized
	In thousands	Value				Gains				(Losses)			Cost
	Fixed maturities:
	U.S. Treasury bonds, agency bonds and foreign government bonds	$	441,685			$	2,854			$	(8,855	)	$	447,686
	States, municipalities and political subdivisions		460,422				9,298				(13,651	)		464,775
	Mortgage-backed and asset-backed securities:
	Agency mortgage-backed securities		301,274				6,779				(6,016	)		300,511
	Residential mortgage obligations		41,755				1,212				(161	)		40,704
	Asset-backed securities		125,133				653				(480	)		124,960
	Commercial mortgage-backed securities		172,750				7,656				(374	)		165,468
	Subtotal	$	640,912			$	16,300			$	(7,031	)	$	631,643
	Corporate bonds		504,854				15,402				(3,443	)		492,895
	Total fixed maturities	$	2,047,873			$	43,854			$	(32,980	)	$	2,036,999
	Equity securities - common stocks		143,954				25,700				(550	)		118,804
	Short-term investments		296,250				—				—			296,250
	Cash		86,509				—				—			86,509
	Total	$	2,574,586			$	69,554			$	(33,530	)	$	2,538,562
	As of March 31, 2014 and December 31, 2013, fixed maturities for which non-credit OTTI was previously recognized and included in other accumulated comprehensive income are now in an unrealized gains position of $0.6 million and $0.5 million, respectively.
	The fair value of the Company’s investment portfolio may fluctuate significantly in response to various factors such as changes in interest rates, investment quality ratings, equity prices, foreign exchange rates and credit spreads. The Company does not have the intent to sell nor is it more likely than not that it will have to sell fix maturities in unrealized loss positions that are not other-than-temporarily impaired before recovery. For structured securities, default probability and severity assumptions differ based on property type, vintage and the stress of the collateral. We do not intend to sell any of these securities and it is more likely than not that we will not be required to sell these securities before the recovery of the amortized cost basis. For equity securities, the Company also considers its intent to hold securities as part of the process of evaluating whether a decline in fair value represents an other-than-temporary decline in value. The Company may realize investment losses to the extent its liquidity needs require the disposition of fixed maturity securities in unfavorable interest rate, liquidity or credit spread environments. Significant changes in the factors the Company considers when evaluating investments for impairment losses could result in a significant change in impairment losses reported in the consolidated financial statements.
	The contractual maturity dates for fixed maturities categorized by the number of years until maturity as of March 31, 2014 are shown in the following table:
		March 31, 2014
		Fair				Amortized
	In thousands	Value				Cost
	Due in one year or less	$	78,570			$	77,743
	Due after one year through five years		739,594				725,355
	Due after five years through ten years		407,558				406,355
	Due after ten years		277,762				277,500
	Mortgage- and asset-backed securities		659,229				646,539
	Total	$	2,162,713			$	2,133,492
	Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Due to the periodic repayment of principal, the mortgage-backed and asset-backed securities are estimated to have an effective maturity of approximately 4.1 years.
	The following table shows the amount and percentage of the Company’s fixed maturities as of March 31, 2014 by S&P credit rating or, if an S&P rating is not available, the equivalent Moody’s Investor Services (“Moody’s”) rating. The table includes fixed maturities at fair value, and the total rating is the weighted average quality rating.
		March 31, 2014
				Fair				Percent
	In thousands	Rating		Value				of Total
	Rating description:
	Extremely strong	AAA		$	389,209				18	%
	Very strong	AA			1,014,656				47	%
	Strong	A			561,731				26	%
	Adequate	BBB			175,311				8	%
Speculative	BB & Below			18,287				1	%
Not rated	NR			3,519				0	%
Total	AA		$	2,162,713				100	%
The following table summarizes all securities in a gross unrealized loss position as of March 31, 2014 and December 31, 2013, showing the aggregate fair value and gross unrealized loss by the length of time those securities had continuously been in a gross unrealized loss position as well as the relevant number of securities.
	March 31, 2014											December 31, 2013
									Gross								Gross
	Number of								Unrealized			Number of					Unrealized
In thousands, except # of securities	Securities				Fair Value				Loss			Securities			Fair Value		Loss
Fixed maturities:
U.S. Treasury bonds, agency bonds, and foreign government bonds
0-6 months		20			$	120,036			$	518			27		$	136,360	$	1,096
7-12 months		21				128,509				4,426			26			149,370		7,759
> 12 months		1				897				12			—			—		—
Subtotal		42			$	249,442			$	4,956			53		$	285,730	$	8,855
States, municipalities and political subdivisions
0-6 months		14			$	24,744			$	163			28		$	40,132	$	297
7-12 months		77				160,382				5,050			104			205,152		12,100
> 12 months		16				36,052				1,735			6			12,357		1,254
Subtotal		107			$	221,178			$	6,948			138		$	257,641	$	13,651
Agency mortgage-backed securities
0-6 months		6			$	22,200			$	65			39		$	39,458	$	434
7-12 months		53				61,847				2,060			64			77,860		3,768
> 12 months		11				22,492				1,400			9			22,784		1,814
Subtotal		70			$	106,539			$	3,525			112		$	140,102	$	6,016
Residential mortgage obligations
0-6 months		2			$	897			$	3			3		$	431	$	2
7-12 months		4				536				18			7			950		29
> 12 months		13				2,222				115			15			2,467		130
Subtotal		19			$	3,655			$	136			25		$	3,848	$	161
Asset-backed securities
0-6 months		7			$	42,213			$	67			14		$	75,887	$	479
7-12 months		3				31,495				496			1			203		1
> 12 months		—				—				—			—			—		—
Subtotal		10			$	73,708			$	563			15		$	76,090	$	480
Commercial mortgage-backed securities
0-6 months		3			$	6,103			$	13			4		$	6,712	$	31
7-12 months		2				15,004				250			2			15,098		322
> 12 months		2				519				9			4			774		21
Subtotal		7			$	21,626			$	272			10		$	22,584	$	374
Corporate bonds
0-6 months		45			$	176,120			$	744			34		$	93,591	$	717
7-12 months		12				45,043				1,575			18			55,021		2,726
> 12 months		1				1,701				—			—			—		—
Subtotal		58			$	222,864			$	2,319			52		$	148,612	$	3,443
Total fixed maturities		313			$	899,012			$	18,719			405		$	934,607	$	32,980
Equity securities - common stocks
0-6 months		10			$	21,578			$	1,120			5		$	7,387	$	422
7-12 months		3				3,794				151			2			3,538		128
> 12 months		—				—				—			—			—		—
Total common Stocks		13			$	25,372			$	1,271			7		$	10,925	$	550
Equity securities - preferred stocks
0-6 months		1			$	553			$	1			—		$	—	$	—
7-12 months		—				—				—			—			—		—
> 12 months		—				—				—			—			—		—
Total Preferred Stocks		1			$	553			$	1			—		$	—	$	—
As of March 31, 2014 and December 31, 2013, the largest unrealized loss by a non-government backed issuer in the investment portfolio was $0.6 million and $1.1 million, respectively.
The Company analyzes impaired securities quarterly to determine if any are other-than-temporary. The above securities with unrealized losses have been determined to be temporarily impaired based on our evaluation.
For fixed maturities, when assessing whether the amortized cost basis of the security will be recovered, the Company compares the present value of cash flows expected to be collected in relation to the current book value. Any shortfalls of the present value of the cash flows expected to be collected to the amortized cost basis is considered the credit loss portion of OTTI losses and is recognized in earnings. All non-credit losses are recognized as changes in OTTI losses within AOCI.
To determine whether the unrealized loss on structured securities is other-than-temporary, the Company analyzes the projections provided by its investment managers with respect to an expected principal loss under a range of scenarios and utilizes the most likely outcomes. The analysis relies on actual collateral performance measures such as default rate, prepayment rate and loss severity. These assumptions are applied throughout the remaining term of the deal, incorporating the transaction structure and priority of payments, to generate loss adjusted cash flows. Results of the analysis will indicate whether the security is expected ultimately to incur a loss or whether there is a material impact on yield due to either a projected loss or a change in cash flow timing. A break even default rate is also calculated. A comparison of the break even default rate to the actual default rate provides an indication of the level of cushion or coverage to the first dollar principal loss. The analysis applies the stated assumptions throughout the remaining term of the transaction to forecast cash flows, which are then applied through the transaction structure to determine whether there is a loss to the security. For securities in which a tranche loss is present, and the net present value of loss adjusted cash flows is less than book value, impairment is recognized. The output data also includes a number of additional metrics such as average life remaining, original and current credit support, over 60 day delinquency and security rating.
The significant inputs used to measure the amount of credit loss recognized in earnings were actual delinquency rates, default probability assumptions, severity assumptions and prepayment assumptions. Projected losses are a function of both loss severity and probability of default. Default probability and severity assumptions differ based on property type, vintage and the stress of the collateral. The Company does not intend to sell any of these securities and it is more likely than not that it will not be required to sell these securities before the recovery of the amortized cost basis.
For equity securities, in general, the Company focuses its attention on those securities with a fair value less than 80% of their cost for six or more consecutive months. If warranted as the result of conditions relating to a particular security, the Company will focus on a significant decline in fair value regardless of the time period involved. Factors considered in evaluating potential impairment include, but are not limited to, the current fair value as compared to cost of the security, the length of time the investment has been below cost and by how much the investment is below cost. If an equity security is deemed to be other-than-temporarily impaired, the cost is written down to fair value with the loss recognized in earnings.
The Company’s ability to hold securities is supported by sufficient cash flow from its operations and from maturities within its investment portfolio in order to meet its claims payment and other disbursement obligations arising from its underwriting operations without selling such investments. With respect to securities where the decline in value is determined to be temporary and the security’s value is not written down, a subsequent decision may be made to sell that security and realize a loss. Subsequent decisions on security sales are made within the context of overall risk monitoring, changing information and market conditions.
As of March 31, 2014, there were no securities with a fair value that was less than 80% of amortized cost.
The table below summarizes the Company’s activity related to OTTI losses for the periods indicated:
	Three Months Ended March 31,
	2014								2013
	Number of								Number of
In thousands, except # of securities	Securities				Amount				Securities			Amount
Total OTTI losses:
Corporate and other bonds		—			$	—				—		$	—
Commercial mortgage-backed securities		—				—				—			—
Residential mortgage-backed securities		—				—				—			—
Asset-backed securities		—				—				—			—
Equities		—				—				2			42
Total		—			$	—				2		$	42
Less: Portion of loss in accumulated other comprehensive income (loss): Corporate and other bonds					$	—						$	—
Commercial mortgage-backed securities						—							—
Residential mortgage-backed securities						—							—
Asset-backed securities						—							—
Equities						—							—
Total					$	—						$	—
Impairment losses recognized in earnings:
Corporate and other bonds					$	—						$	—
Commercial mortgage-backed securities						—							—
Residential mortgage-backed securities						—							—
Asset-backed securities						—							—
Equities						—							42
Total					$	—						$	42
The following table summarizes the cumulative amounts related to the Company’s credit loss portion of the OTTI losses on debt securities for the three months ended March 31, 2014 and 2013. The Company does not intend to sell and it is more likely than not that it will not be required to sell the securities, prior to recovery of the amortized cost basis and for which the non-credit loss portion is included in AOCI.
	Three Months Ended March 31,
In thousands	2014				2013
Beginning balance	$	4,183			$	2,362
Additions for credit loss impairments recognized in the current period on securities not previously impaired		—				—
Additions for credit loss impairments recognized in the current period on securities previously impaired		—				—
Reductions for credit loss impairments previously recognized on securities sold during the period		—				—
Ending balance	$	4,183			$	2,362
The contractual maturity dates for fixed maturities categorized by the number of years until maturity, with a gross unrealized loss as of March 31, 2014 is presented in the following table:
	March 31, 2014
	Gross Unrealized Losses								Fair Value
In thousands	Amount				Percent				Amount			Percent
					of Total							of Total
Due in one year or less	$	—				0	%		$	1,701			0	%
Due after one year through five years		1,697				9	%			316,024			35	%
Due after five years through ten years		7,773				41	%			235,549			26	%
Due after ten years		4,753				26	%			140,210			16	%
Mortgage- and asset-backed securities		4,496				24	%			205,528			23	%
Total	$	18,719				100	%		$	899,012			100	%
The Company’s net investment income was derived from the following sources:
	Three Months Ended March 31,
In thousands	2014				2013
Fixed maturities	$	13,953			$	13,167
Equity securities		3,233				1,030
Short-term investments		218				189
Total investment income	$	17,404			$	14,386
Investment expenses		(794	)			(729	)
Net investment income	$	16,610			$	13,657
The change in net unrealized gains and losses, inclusive of the change in the non credit portion of other-than-temporary impairment losses, consisted of:
	Three Months Ended March 31,
In thousands	2014				2013
Fixed maturities	$	18,347			$	(10,930	)
Equity securities		1,019				8,172
Gross unrealized gains (losses)	$	19,366			$	(2,758	)
Deferred income tax		6,675				(1,003	)
Change in net unrealized gains (losses), net	$	12,691			$	(1,755	)
Realized gains and losses, excluding net OTTI losses recognized in earnings, for the periods indicated were as follows:
	Three Months Ended March 31,
In thousands	2014				2013
Fixed maturities:
Gains	$	1,867			$	3,206
Losses		(2,051	)			(310	)
Fixed maturities, net	$	(184	)		$	2,896
Equity securities:
Gains	$	1,920			$	1,918
Losses		(903	)			—
Equity securities, net	$	1,017			$	1,918
Net realized gains (losses)	$	833			$	4,814
The following tables present, for each of the fair value hierarchy levels as defined by the accounting guidance for fair value measurements and described below, the Company’s fixed maturities and equity securities by asset class that are measured at fair value on a recurring basis as of March 31, 2014 and December 31, 2013
	March 31, 2014
In thousands	Level 1				Level 2				Level 3			Total
Fixed maturities:
U.S. Treasury bonds, agency bonds and foreign government bonds	$	217,631			$	200,311			$	—		$	417,942
States, municipalities and political subdivisions		—				491,598				—			491,598
Mortgage-backed and asset-backed securities:													—
Agency mortgage-backed securities		—				265,818				—			265,818
Residential mortgage obligations		—				57,852				—			57,852
Asset-backed securities		—				162,226				—			162,226
Commercial mortgage-backed securities		—				173,333				—			173,333
Subtotal	$	—			$	659,229			$	—		$	659,229
Corporate bonds		—				593,944				—			593,944
Total fixed maturities	$	217,631			$	1,945,082			$	—		$	2,162,713
Equity securities - common stocks		141,476				—				—			141,476
Equity securities - preferred stocks						22,051							22,051
Total	$	359,107			$	1,967,133			$	—		$	2,326,240
	December 31, 2013
In thousands	Level 1				Level 2				Level 3			Total
Fixed maturities:
U.S. Treasury bonds, agency bonds and foreign government bonds	$	242,379			$	199,306			$	—		$	441,685
States, municipalities and political subdivisions		—				460,422				—			460,422
Mortgage-backed and asset-backed securities:
Agency mortgage-backed securities		—				301,274				—			301,274
Residential mortgage obligations		—				41,755				—			41,755
Asset-backed securities		—				125,133				—			125,133
Commercial mortgage-backed securities		—				172,750				—			172,750
Subtotal	$	—			$	640,912			$	—		$	640,912
Corporate bonds		—				500,447				4,407			504,854
Total fixed maturities	$	242,379			$	1,801,087			$	4,407		$	2,047,873
Equity securities - common stocks		143,954				—				—			143,954
Total	$	386,333			$	1,801,087			$	4,407		$	2,191,827
The fair value of financial instruments is determined based on the following fair value hierarchy:
Level 1 – Quoted prices for identical instruments in active markets. Examples are listed equity and fixed income securities traded on an exchange. U.S. Treasury securities are reported as Level 1 and are valued based on unadjusted quoted prices for identical assets in active markets that the Company can access.
Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. Examples are asset-backed and mortgage-backed securities that are similar to other asset-backed or mortgage-backed securities observed in the market. U.S. government agency securities are reported as Level 2 and are valued using yields and spreads that are observable in active markets.
Level 3 – Valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. An example would be a private placement with minimal liquidity.
The Company did not have any significant transfers between Level 1 and 2 as of March 31, 2014 and March 31, 2013.
The following tables present a reconciliation of the beginning and ending balances of all investments measured at fair value using Level 3 inputs during the three months ended March 31, 2014.
	Three Months Ended March 31, 2014
In thousands	Beginning				Realized				Unrealized			Purchases			Sales		Settlements		Transfers		Transfers			Ending
	Balance				Gains				Gains										into Level 3		out of Level 3			Balance
					(Losses)				(Losses)
Assets:
Corporate Bonds	$	4,407			$	—			$	—		$	—		$	—	$	—	$	—	$	(4,407	)	$	—
Total assets	$	4,407			$	—			$	—		$	—		$	—	$	—	$	—	$	(4,407	)	$	—
As of March 31, 2013, the Company did not have any Level 3 assets
As of March 31, 2014 and December 31, 2013, the Company did not have a concentration of greater than 5% of invested assets in a single non-U.S. government-backed issuer.

Credit_Facility

Credit Facility	3 Months Ended
	Mar. 31, 2014
Credit Facility	'
	Note 10. Credit Facility
	On November 22, 2012, we entered into a $165 million credit facility agreement with ING Bank N.V., London Branch, individually and as Administrative Agent, and a syndicate of lenders. The new credit facility amended and restated a $165 million letter of credit facility entered into by the parties on March 28, 2011. The credit facility, which is denominated in U.S. dollars, is utilized to fund our participation in Syndicate 1221 through letters of credit for the 2013 and 2014 underwriting years, as well as open prior years. The letters of credit issued under the facility can be denominated in British pounds and their aggregate face amount will fluctuate based on exchange rates. If any letters of credit remain outstanding under the facility after December 31, 2014, we would be required to post additional collateral to secure the remaining letters of credit. As of March 31, 2014, letters of credit with an aggregate face amount of $152.1 million were outstanding under the credit facility and we have $1.0 million of cash collateral posted.
	This credit facility contains customary covenants for facilities of this type, including restrictions on indebtedness and liens, limitations on mergers, dividends and the sale of assets, and requirements as to maintaining certain consolidated tangible net worth, statutory surplus and other financial ratios. The credit facility also provides for customary events of default, including failure to pay principal, interest or fees when due, failure to comply with covenants, any representation or warranty made by the Company being false in any material respect, default under certain other indebtedness, certain insolvency or receivership events affecting the Company and its subsidiaries, the occurrence of certain material judgments, or a change in control of the Company. The letter of credit facility is secured by a pledge of the stock of certain insurance subsidiaries of the Company. To the extent the aggregate face amount issued under the credit facility exceeds the commitment amount, the Company is required to post collateral with the lead bank of the consortium. The Company was in compliance with all covenants under the credit facility as of March 31, 2014.
	The applicable margin and applicable fee rate payable under the credit facility are based on a tiered schedule that is based on the Company’s then-current ratings issued by S&P and Moody’s with respect to the Company’s Senior Notes without third-party credit enhancement, and the amount of the Company’s own collateral utilized to fund its participation in Syndicate 1221.

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2014
Financial Data by Segment	'
	Financial data by segment for the three months ended March 31, 2014 and 2013 were as follows:
		Three Month Ended March 31, 2014
	In thousands	Insurance			Lloyd’s			Corporate (1)			Total
		Companies			Operations
	Gross written premiums	$	311,798		$	110,992		$	—		$	422,790
	Net written premiums		233,951			77,899			—			311,850
	Net earned premiums		165,884			59,388			—			225,272
	Net losses and loss adjustment expenses		(106,427	)		(28,640	)		—			(135,067	)
	Commission expenses		(16,710	)		(9,526	)		509			(25,727	)
	Other operating expenses		(33,361	)		(13,785	)		—			(47,146	)
	Other underwriting income (expense)		658			6			(509	)		155
	Underwriting profit (loss)	$	10,044		$	7,443		$	—		$	17,487
	Net investment income		14,777			1,815			18			16,610
	Net realized gains (losses)		1,237			(404	)		—			833
	Interest expense		—			—			(3,852	)		(3,852	)
	Other income		49			10,195			—			10,244
	Income (loss) before income taxes	$	26,107		$	19,049		$	(3,834	)	$	41,322
	Income tax expense (benefit)		8,112			6,638			(1,396	)		13,354
	Net income (loss)	$	17,995		$	12,411		$	(2,438	)	$	27,968
	Identifiable assets	$	3,203,763		$	941,426		$	154,616		$	4,299,805
	Losses and loss adjustment expenses ratio		64.2	%		48.2	%					60	%
	Commission expense ratio		10.1	%		16	%					11.4	%
	Other operating expense ratio (2)		19.6	%		23.3	%					20.8	%
	Combined ratio		93.9	%		87.5	%					92.2	%
	(1) - Includes Corporate segment intercompany eliminations.
	(2) - Includes Other operating expenses and Other underwriting income.
		Three Month Ended March 31, 2013
	In thousands	Insurance			Lloyd’s			Corporate (1)			Total
		Companies			Operations
	Gross written premiums	$	301,628		$	91,594		$	—		$	393,222
	Net written premiums		216,319			53,133			—			269,452
	Net earned premiums		154,331			47,997			—			202,328
	Net losses and loss adjustment expenses		(106,985	)		(24,357	)		—			(131,342	)
	Commission expenses		(18,517	)		(8,621	)		583			(26,555	)
	Other operating expenses		(29,343	)		(11,531	)		—			(40,874	)
	Other income (expense)		659			542			(583	)		618
	Underwriting profit (loss)	$	145		$	4,030		$	—		$	4,175
	Net investment income		11,951			1,702			4			13,657
	Net realized gains (losses)		4,792			(20	)		—			4,772
	Interest expense		—			—			(2,051	)		(2,051	)
	Income (loss) before income taxes	$	16,888		$	5,712		$	(2,047	)	$	20,553
	Income tax expense (benefit)		5,404			2,046			(807	)		6,643
	Net income (loss)	$	11,484		$	3,666		$	(1,240	)	$	13,910
	Identifiable assets	$	3,087,308		$	936,471		$	47,266		$	4,071,045
	Losses and loss adjustment expenses ratio		69.3	%		50.7	%					64.9	%
	Commission expense ratio		12	%		18	%					13.1	%
	Other operating expense ratio (2)		18.6	%		22.9	%					19.9	%
	Combined ratio		99.9	%		91.6	%					97.9	%
	(1) - Includes Corporate segment intercompany eliminations.
	(2) - Includes Other operating expenses and Other income.
Additional Financial Data by Segment	'
	The following tables provide additional financial data by segment for the three months ended March 31, 2014 and 2013:
	In thousands
	Gross Written Premiums:	Three Months
	Insurance Companies:	2014			2013
	Marine	$	52,233		$	50,847
	Property Casualty		229,356			218,964
	Professional Liability		30,209			31,817
			311,798			301,628
	Lloyd’s Operations:
	Marine		62,957			53,644
	Property Casualty		33,079			25,058
	Professional Liability		14,956			12,892
			110,992			91,594
	Total	$	422,790		$	393,222
	Net Written Premiums:	Three Months
	Insurance Companies:	2014			2013
	Marine	$	41,124		$	41,141
	Property Casualty		172,361			149,951
	Professional Liability		20,466			25,227
			233,951			216,319
	Lloyd’s Operations:
	Marine		52,131			39,558
	Property Casualty		16,534			7,312
	Professional Liability		9,234			6,263
			77,899			53,133
	Total	$	311,850		$	269,452
	Net Earned Premiums:	Three Months
	Insurance Companies:	2014			2013
	Marine	$	32,760		$	36,725
	Property Casualty		110,826			92,718
	Professional Liability		22,298			24,888
			165,884			154,331
	Lloyd’s Operations:
	Marine		38,887			34,045
	Property Casualty		12,958			7,879
	Professional Liability		7,543			6,073
			59,388			47,997
	Total	$	225,272		$	202,328

Reinsurance_Ceded_Tables

Reinsurance Ceded (Tables)	3 Months Ended
	Mar. 31, 2014
Lists of 20 Largest Reinsurers Measured by Reinsurance Recoverable	'
	The following table lists the Company’s 20 largest reinsurers measured by the amount of reinsurance recoverable for ceded losses and LAE and ceded unearned premium (constituting 76.2% of the total recoverable), together with the reinsurance recoverable and collateral as of March 31, 2014, and the reinsurers’ ratings from A.M. Best Company (“A.M. Best”) or Standard & Poor’s (“S&P”):
		Reinsurance Recoverables
	In thousands	Unearned		Paid/Unpaid		Total (1)		Collateral		A.M. Best	S&P
		Premium		Losses				Held (2)
	National Indemnity Company	$	50,635	$	101,575	$	152,210	$	30,795	A++	AA+
	Transatlantic Reinsurance Company		19,819		75,865		95,684		6,984	A	A+
	Everest Reinsurance Company		21,782		70,793		92,575		7,706	A+	A+
	Munich Reinsurance America Inc.		5,505		68,798		74,303		4,510	A+	AA-
	Swiss Reinsurance America Corporation		7,690		63,942		71,632		4,759	A+	AA-
	Lloyd’s Syndicate #2003		6,704		40,585		47,289		5,977	A	A+
	Allied World Reinsurance		13,380		33,043		46,423		3,129	A	A
	Partner Reinsurance Europe		9,483		29,208		38,691		16,623	A+	A+
	Scor Global P&C SE		9,690		22,199		31,889		6,724	A	A+
	Employers Mutual Casualty Company		11,368		14,766		26,134		10,689	A	NR
	Atlantic Specialty Insurance		6,741		15,944		22,685		839	A	A-
	Tower Insurance Company		—		21,738		21,738		1,803	B	NR
	QBE Reinsurance Corp		6,666		12,827		19,493		1,043	A	A+
	Ace Property and Casualty Insurance Company		10,108		7,884		17,992		4,152	A++	AA-
	Validus Reinsurance Ltd.		2,316		15,198		17,514		12,140	A	A
	Ironshore Indemnity Inc.		7,224		10,248		17,472		9,273	A	NR
	Lloyd’s Syndicate #4000		96		16,127		16,223		111	A	A+
	Odyssey American Reinsurance Corporation		3,420		12,425		15,845		1,545	A	A-
	Berkley Insurance Company		2,096		11,846		13,942		—	A+	A+
	AXIS Re Europe		4,108		9,453		13,561		3,724	A+	A+
	Top 20 Reinsurers	$	198,831	$	654,464	$	853,295	$	132,526
	Others		47,714		218,227		265,941		72,914
	Total	$	246,545	$	872,691	$	1,119,236	$	205,440
	(1) - Net of reserve for uncollectible reinsurance of approximately $11.3 million.
	(2) - Collateral of $205.4 million consists of $145.9 million in ceded balances payable, $53.4 million in letters of credit, and $6.1 million of other balances held by the Company’s Insurance Companies and Lloyd’s Operations.

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Amounts Charged to Expense for Stock-based Compensation	'
	The amounts charged to expense for stock-based compensation for the three months ended March 31, 2014 and 2013 are presented in the following table:
			Three Months Ended March 31,
	In thousands		2014		2013
	Restricted stock units		$	1,886	$	1,358
	Directors restricted stock grants(1)			100		100
	Employee stock purchase plan			74		9
	Total stock based compensation		$	2,060	$	1,467
	(1) -	Relates to non-employee directors serving on the Parent Company’s Board of Directors, all of whom have been elected by the Company’s stockholders, as well as non-employee directors serving on NUAL’s Board of Directors.

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2014
Cash and Investments Including Other-Than-Temporarily Impaired Securities Recognized within Accumulated Other Comprehensive Income	'
	The following tables set forth the Company’s cash and investments as of March 31, 2014 and December 31, 2013. The table below includes other-than-temporarily impaired (“OTTI”) securities recognized within accumulated other comprehensive income (“AOCI”).
		March 31, 2014
						Gross				Gross			Cost or
		Fair				Unrealized				Unrealized			Amortized
	In thousands	Value				Gains				(Losses)			Cost
	Fixed maturities:
	U.S. Treasury bonds, agency bonds and foreign government bonds	$	417,942			$	3,066			$	(4,956	)	$	419,832
	States, municipalities and political subdivisions		491,598				12,216				(6,948	)		486,330
	Mortgage-backed and asset-backed securities:
	Agency mortgage-backed securities		265,818				7,182				(3,525	)		262,161
	Residential mortgage obligations		57,852				1,573				(136	)		56,415
	Asset-backed securities		162,226				639				(563	)		162,150
	Commercial mortgage-backed securities		173,333				7,792				(272	)		165,813
	Subtotal	$	659,229			$	17,186			$	(4,496	)	$	646,539
	Corporate bonds		593,944				15,472				(2,319	)		580,791
	Total fixed maturities	$	2,162,713			$	47,940			$	(18,719	)	$	2,133,492
	Equity securities - common stocks		141,476				26,589				(1,271	)		116,158
	Equity securities - Preferred stocks		22,051				852				(1	)		21,200
	Short-term investments		207,843				—				—			207,843
	Cash		55,041				—				—			55,041
	Total	$	2,589,124			$	75,381			$	(19,991	)	$	2,533,734
		December 31, 2013
						Gross				Gross			Cost or
		Fair				Unrealized				Unrealized			Amortized
	In thousands	Value				Gains				(Losses)			Cost
	Fixed maturities:
	U.S. Treasury bonds, agency bonds and foreign government bonds	$	441,685			$	2,854			$	(8,855	)	$	447,686
	States, municipalities and political subdivisions		460,422				9,298				(13,651	)		464,775
	Mortgage-backed and asset-backed securities:
	Agency mortgage-backed securities		301,274				6,779				(6,016	)		300,511
	Residential mortgage obligations		41,755				1,212				(161	)		40,704
	Asset-backed securities		125,133				653				(480	)		124,960
	Commercial mortgage-backed securities		172,750				7,656				(374	)		165,468
	Subtotal	$	640,912			$	16,300			$	(7,031	)	$	631,643
	Corporate bonds		504,854				15,402				(3,443	)		492,895
	Total fixed maturities	$	2,047,873			$	43,854			$	(32,980	)	$	2,036,999
	Equity securities - common stocks		143,954				25,700				(550	)		118,804
	Short-term investments		296,250				—				—			296,250
	Cash		86,509				—				—			86,509
	Total	$	2,574,586			$	69,554			$	(33,530	)	$	2,538,562
Scheduled Maturity Dates for Fixed Maturity Securities by Number of Years Until Maturity	'
	The contractual maturity dates for fixed maturities categorized by the number of years until maturity as of March 31, 2014 are shown in the following table:
		March 31, 2014
		Fair				Amortized
	In thousands	Value				Cost
	Due in one year or less	$	78,570			$	77,743
	Due after one year through five years		739,594				725,355
	Due after five years through ten years		407,558				406,355
	Due after ten years		277,762				277,500
	Mortgage- and asset-backed securities		659,229				646,539
	Total	$	2,162,713			$	2,133,492
Amount and Percentage of Fixed Maturities by Rating	'
	The following table shows the amount and percentage of the Company’s fixed maturities as of March 31, 2014 by S&P credit rating or, if an S&P rating is not available, the equivalent Moody’s Investor Services (“Moody’s”) rating. The table includes fixed maturities at fair value, and the total rating is the weighted average quality rating.
		March 31, 2014
				Fair				Percent
	In thousands	Rating		Value				of Total
	Rating description:
	Extremely strong	AAA		$	389,209				18	%
	Very strong	AA			1,014,656				47	%
	Strong	A			561,731				26	%
	Adequate	BBB			175,311				8	%
	Speculative	BB & Below			18,287				1	%
	Not rated	NR			3,519				0	%
	Total	AA		$	2,162,713				100	%
Summary of Aggregate Fair Value and Gross Unrealized Loss by Length of Time Securities had Continuously been in Gross Unrealized Loss Position as Well as Number of Securities	'
	The following table summarizes all securities in a gross unrealized loss position as of March 31, 2014 and December 31, 2013, showing the aggregate fair value and gross unrealized loss by the length of time those securities had continuously been in a gross unrealized loss position as well as the relevant number of securities.
		March 31, 2014											December 31, 2013
										Gross								Gross
		Number of								Unrealized			Number of					Unrealized
	In thousands, except # of securities	Securities				Fair Value				Loss			Securities			Fair Value		Loss
	Fixed maturities:
	U.S. Treasury bonds, agency bonds, and foreign government bonds
	0-6 months		20			$	120,036			$	518			27		$	136,360	$	1,096
	7-12 months		21				128,509				4,426			26			149,370		7,759
	> 12 months		1				897				12			—			—		—
	Subtotal		42			$	249,442			$	4,956			53		$	285,730	$	8,855
	States, municipalities and political subdivisions
	0-6 months		14			$	24,744			$	163			28		$	40,132	$	297
	7-12 months		77				160,382				5,050			104			205,152		12,100
	> 12 months		16				36,052				1,735			6			12,357		1,254
	Subtotal		107			$	221,178			$	6,948			138		$	257,641	$	13,651
	Agency mortgage-backed securities
	0-6 months		6			$	22,200			$	65			39		$	39,458	$	434
	7-12 months		53				61,847				2,060			64			77,860		3,768
	> 12 months		11				22,492				1,400			9			22,784		1,814
	Subtotal		70			$	106,539			$	3,525			112		$	140,102	$	6,016
	Residential mortgage obligations
	0-6 months		2			$	897			$	3			3		$	431	$	2
	7-12 months		4				536				18			7			950		29
	> 12 months		13				2,222				115			15			2,467		130
	Subtotal		19			$	3,655			$	136			25		$	3,848	$	161
	Asset-backed securities
	0-6 months		7			$	42,213			$	67			14		$	75,887	$	479
	7-12 months		3				31,495				496			1			203		1
	> 12 months		—				—				—			—			—		—
	Subtotal		10			$	73,708			$	563			15		$	76,090	$	480
	Commercial mortgage-backed securities
	0-6 months		3			$	6,103			$	13			4		$	6,712	$	31
	7-12 months		2				15,004				250			2			15,098		322
	> 12 months		2				519				9			4			774		21
	Subtotal		7			$	21,626			$	272			10		$	22,584	$	374
	Corporate bonds
	0-6 months		45			$	176,120			$	744			34		$	93,591	$	717
	7-12 months		12				45,043				1,575			18			55,021		2,726
	> 12 months		1				1,701				—			—			—		—
	Subtotal		58			$	222,864			$	2,319			52		$	148,612	$	3,443
	Total fixed maturities		313			$	899,012			$	18,719			405		$	934,607	$	32,980
	Equity securities - common stocks
	0-6 months		10			$	21,578			$	1,120			5		$	7,387	$	422
	7-12 months		3				3,794				151			2			3,538		128
	> 12 months		—				—				—			—			—		—
	Total common Stocks		13			$	25,372			$	1,271			7		$	10,925	$	550
	Equity securities - preferred stocks
	0-6 months		1			$	553			$	1			—		$	—	$	—
	7-12 months		—				—				—			—			—		—
	> 12 months		—				—				—			—			—		—
	Total Preferred Stocks		1			$	553			$	1			—		$	—	$	—
Summary of Activity Related to Other-Than-Temporary Impairment Losses	'
	The table below summarizes the Company’s activity related to OTTI losses for the periods indicated:
		Three Months Ended March 31,
		2014								2013
		Number of								Number of
	In thousands, except # of securities	Securities				Amount				Securities			Amount
	Total OTTI losses:
	Corporate and other bonds		—			$	—				—		$	—
	Commercial mortgage-backed securities		—				—				—			—
	Residential mortgage-backed securities		—				—				—			—
	Asset-backed securities		—				—				—			—
	Equities		—				—				2			42
	Total		—			$	—				2		$	42
	Less: Portion of loss in accumulated other comprehensive income (loss): Corporate and other bonds					$	—						$	—
	Commercial mortgage-backed securities						—							—
	Residential mortgage-backed securities						—							—
	Asset-backed securities						—							—
	Equities						—							—
	Total					$	—						$	—
	Impairment losses recognized in earnings:
	Corporate and other bonds					$	—						$	—
	Commercial mortgage-backed securities						—							—
	Residential mortgage-backed securities						—							—
	Asset-backed securities						—							—
	Equities						—							42
	Total					$	—						$	42
Summary of Cumulative Amounts Related to Credit Loss Portion of Other-Than-Temporary Impairment Losses on Debt Securities	'
	The following table summarizes the cumulative amounts related to the Company’s credit loss portion of the OTTI losses on debt securities for the three months ended March 31, 2014 and 2013. The Company does not intend to sell and it is more likely than not that it will not be required to sell the securities, prior to recovery of the amortized cost basis and for which the non-credit loss portion is included in AOCI.
		Three Months Ended March 31,
	In thousands	2014				2013
	Beginning balance	$	4,183			$	2,362
	Additions for credit loss impairments recognized in the current period on securities not previously impaired		—				—
	Additions for credit loss impairments recognized in the current period on securities previously impaired		—				—
	Reductions for credit loss impairments previously recognized on securities sold during the period		—				—
	Ending balance	$	4,183			$	2,362
Contractual Maturity by Number of Years Until Maturity for Fixed Maturity Securities with a Gross Unrealized Loss	'
	The contractual maturity dates for fixed maturities categorized by the number of years until maturity, with a gross unrealized loss as of March 31, 2014 is presented in the following table:
		March 31, 2014
		Gross Unrealized Losses								Fair Value
	In thousands	Amount				Percent				Amount			Percent
						of Total							of Total
	Due in one year or less	$	—				0	%		$	1,701			0	%
	Due after one year through five years		1,697				9	%			316,024			35	%
	Due after five years through ten years		7,773				41	%			235,549			26	%
	Due after ten years		4,753				26	%			140,210			16	%
	Mortgage- and asset-backed securities		4,496				24	%			205,528			23	%
	Total	$	18,719				100	%		$	899,012			100	%
Net Investment Income	'
	The Company’s net investment income was derived from the following sources:
		Three Months Ended March 31,
	In thousands	2014				2013
	Fixed maturities	$	13,953			$	13,167
	Equity securities		3,233				1,030
	Short-term investments		218				189
	Total investment income	$	17,404			$	14,386
	Investment expenses		(794	)			(729	)
	Net investment income	$	16,610			$	13,657
Change in Net Unrealized Gains/(Losses)	'
	The change in net unrealized gains and losses, inclusive of the change in the non credit portion of other-than-temporary impairment losses, consisted of:
		Three Months Ended March 31,
	In thousands	2014				2013
	Fixed maturities	$	18,347			$	(10,930	)
	Equity securities		1,019				8,172
	Gross unrealized gains (losses)	$	19,366			$	(2,758	)
	Deferred income tax		6,675				(1,003	)
	Change in net unrealized gains (losses), net	$	12,691			$	(1,755	)
Realized Gains and Losses Excluding Net Other-Than-Temporary Impairment Losses Recognized in Earnings	'
	Realized gains and losses, excluding net OTTI losses recognized in earnings, for the periods indicated were as follows:
		Three Months Ended March 31,
	In thousands	2014				2013
	Fixed maturities:
	Gains	$	1,867			$	3,206
	Losses		(2,051	)			(310	)
	Fixed maturities, net	$	(184	)		$	2,896
	Equity securities:
	Gains	$	1,920			$	1,918
	Losses		(903	)			—
	Equity securities, net	$	1,017			$	1,918
	Net realized gains (losses)	$	833			$	4,814
Fixed Maturities and Equity Securities by Asset Class that are Measured at Fair Value	'
	The following tables present, for each of the fair value hierarchy levels as defined by the accounting guidance for fair value measurements and described below, the Company’s fixed maturities and equity securities by asset class that are measured at fair value on a recurring basis as of March 31, 2014 and December 31, 2013
		March 31, 2014
	In thousands	Level 1				Level 2				Level 3			Total
	Fixed maturities:
	U.S. Treasury bonds, agency bonds and foreign government bonds	$	217,631			$	200,311			$	—		$	417,942
	States, municipalities and political subdivisions		—				491,598				—			491,598
	Mortgage-backed and asset-backed securities:													—
	Agency mortgage-backed securities		—				265,818				—			265,818
	Residential mortgage obligations		—				57,852				—			57,852
	Asset-backed securities		—				162,226				—			162,226
	Commercial mortgage-backed securities		—				173,333				—			173,333
	Subtotal	$	—			$	659,229			$	—		$	659,229
	Corporate bonds		—				593,944				—			593,944
	Total fixed maturities	$	217,631			$	1,945,082			$	—		$	2,162,713
	Equity securities - common stocks		141,476				—				—			141,476
	Equity securities - preferred stocks						22,051							22,051
	Total	$	359,107			$	1,967,133			$	—		$	2,326,240
		December 31, 2013
	In thousands	Level 1				Level 2				Level 3			Total
	Fixed maturities:
	U.S. Treasury bonds, agency bonds and foreign government bonds	$	242,379			$	199,306			$	—		$	441,685
	States, municipalities and political subdivisions		—				460,422				—			460,422
	Mortgage-backed and asset-backed securities:
	Agency mortgage-backed securities		—				301,274				—			301,274
	Residential mortgage obligations		—				41,755				—			41,755
	Asset-backed securities		—				125,133				—			125,133
	Commercial mortgage-backed securities		—				172,750				—			172,750
	Subtotal	$	—			$	640,912			$	—		$	640,912
	Corporate bonds		—				500,447				4,407			504,854
	Total fixed maturities	$	242,379			$	1,801,087			$	4,407		$	2,047,873
	Equity securities - common stocks		143,954				—				—			143,954
	Total	$	386,333			$	1,801,087			$	4,407		$	2,191,827
Reconciliation of Beginning and Ending Balances for All Investments Measured at Fair Value Using Level 3 Inputs	'
	The following tables present a reconciliation of the beginning and ending balances of all investments measured at fair value using Level 3 inputs during the three months ended March 31, 2014.
		Three Months Ended March 31, 2014
	In thousands	Beginning				Realized				Unrealized			Purchases			Sales		Settlements		Transfers		Transfers			Ending
		Balance				Gains				Gains										into Level 3		out of Level 3			Balance
						(Losses)				(Losses)
	Assets:
	Corporate Bonds	$	4,407			$	—			$	—		$	—		$	—	$	—	$	—	$	(4,407	)	$	—
	Total assets	$	4,407			$	—			$	—		$	—		$	—	$	—	$	—	$	(4,407	)	$	—

Organization_and_Summary_of_Si

Organization and Summary of Significant Accounting Policies - Additional Information (Detail)	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Navigators Insurance Company	'	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'	'
Percentage of Navigators Specialty Insurance Company reinsured by Navigators Insurance Company	100.00%	'	'
Lloyd's | Syndicate 1221	'	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'	'
Percentage control of stamp capacity	100.00%	100.00%	100.00%

Segment_Information_Additional

Segment Information - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
	Segment
Segment Reporting Information [Line Items]	'	'
Number of underwriting segments	2	'
Combined ratio indicating underwriting profit	100.00%	'
Combined ratio indicating underwriting loss	100.00%	'
Net earned premiums	$225,272	$202,328
Insurance Companies	'	'
Segment Reporting Information [Line Items]	'	'
Net earned premiums	165,884	154,331
Insurance Companies | UK Branch	'	'
Segment Reporting Information [Line Items]	'	'
Net earned premiums	$11,600	$10,100

Financial_Data_by_Segment_Deta

Financial Data by Segment (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Segment Reporting Information [Line Items]	'		'		'
Gross written premiums	$422,790		$393,222		'
Net written premiums	311,850		269,452		'
Net earned premiums	225,272		202,328		'
Net losses and loss adjustment expenses	-135,067		-131,342		'
Commission expenses	-25,727		-26,555		'
Other operating expenses	-47,146		-40,874		'
Other underwriting income (expense)	155		'		'
Other income (expense)	10,399		618		'
Underwriting profit (loss)	17,487		4,175		'
Net investment income	16,610		13,657		'
Net realized gains (losses)	833		4,772		'
Interest expense	-3,852		-2,051		'
Other income	10,244		'		'
Income (loss) before income taxes	41,322		20,553		'
Income tax expense (benefit)	13,354		6,643		'
Net income (loss)	27,968		13,910		'
Identifiable assets	4,299,805		4,071,045		4,169,452
Losses and loss adjustment expenses ratio	60.00%		64.90%		'
Commission expense ratio	11.40%		13.10%		'
Other operating expense ratio	20.80%	[1]	19.90%	[2]	'
Combined ratio	92.20%		97.90%		'
Insurance Companies	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Gross written premiums	311,798		301,628		'
Net written premiums	233,951		216,319		'
Net earned premiums	165,884		154,331		'
Net losses and loss adjustment expenses	-106,427		-106,985		'
Commission expenses	-16,710		-18,517		'
Other operating expenses	-33,361		-29,343		'
Other underwriting income (expense)	658		'		'
Other income (expense)	'		659		'
Underwriting profit (loss)	10,044		145		'
Net investment income	14,777		11,951		'
Net realized gains (losses)	1,237		4,792		'
Other income	49		'		'
Income (loss) before income taxes	26,107		16,888		'
Income tax expense (benefit)	8,112		5,404		'
Net income (loss)	17,995		11,484		'
Identifiable assets	3,203,763		3,087,308		'
Losses and loss adjustment expenses ratio	64.20%		69.30%		'
Commission expense ratio	10.10%		12.00%		'
Other operating expense ratio	19.60%	[1]	18.60%	[2]	'
Combined ratio	93.90%		99.90%		'
Lloyd's	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Gross written premiums	110,992		91,594		'
Net written premiums	77,899		53,133		'
Net earned premiums	59,388		47,997		'
Net losses and loss adjustment expenses	-28,640		-24,357		'
Commission expenses	-9,526		-8,621		'
Other operating expenses	-13,785		-11,531		'
Other underwriting income (expense)	6		'		'
Other income (expense)	'		542		'
Underwriting profit (loss)	7,443		4,030		'
Net investment income	1,815		1,702		'
Net realized gains (losses)	-404		-20		'
Other income	10,195		'		'
Income (loss) before income taxes	19,049		5,712		'
Income tax expense (benefit)	6,638		2,046		'
Net income (loss)	12,411		3,666		'
Identifiable assets	941,426		936,471		'
Losses and loss adjustment expenses ratio	48.20%		50.70%		'
Commission expense ratio	16.00%		18.00%		'
Other operating expense ratio	23.30%	[1]	22.90%	[2]	'
Combined ratio	87.50%		91.60%		'
Corporate	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Commission expenses	509	[3]	583	[3]	'
Other underwriting income (expense)	-509	[3]	'		'
Other income (expense)	'		-583	[3]	'
Net investment income	18	[3]	4	[3]	'
Interest expense	-3,852	[3]	-2,051	[3]	'
Income (loss) before income taxes	-3,834	[3]	-2,047	[3]	'
Income tax expense (benefit)	-1,396	[3]	-807	[3]	'
Net income (loss)	-2,438	[3]	-1,240	[3]	'
Identifiable assets	$154,616	[3]	$47,266	[3]	'
[1]	Includes Other operating expenses and Other underwriting income.
[2]	Includes Other operating expenses and Other income.
[3]	Includes Corporate segment intercompany eliminations.

Additional_Financial_Data_by_S

Additional Financial Data by Segment (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]	'	'
Gross written premiums	$422,790	$393,222
Net written premiums	311,850	269,452
Net earned premiums	225,272	202,328
Insurance Companies	'	'
Segment Reporting Information [Line Items]	'	'
Gross written premiums	311,798	301,628
Net written premiums	233,951	216,319
Net earned premiums	165,884	154,331
Insurance Companies | Marine	'	'
Segment Reporting Information [Line Items]	'	'
Gross written premiums	52,233	50,847
Net written premiums	41,124	41,141
Net earned premiums	32,760	36,725
Insurance Companies | Property Casualty	'	'
Segment Reporting Information [Line Items]	'	'
Gross written premiums	229,356	218,964
Net written premiums	172,361	149,951
Net earned premiums	110,826	92,718
Insurance Companies | Professional Liability	'	'
Segment Reporting Information [Line Items]	'	'
Gross written premiums	30,209	31,817
Net written premiums	20,466	25,227
Net earned premiums	22,298	24,888
Lloyd's	'	'
Segment Reporting Information [Line Items]	'	'
Gross written premiums	110,992	91,594
Net written premiums	77,899	53,133
Net earned premiums	59,388	47,997
Lloyd's | Marine	'	'
Segment Reporting Information [Line Items]	'	'
Gross written premiums	62,957	53,644
Net written premiums	52,131	39,558
Net earned premiums	38,887	34,045
Lloyd's | Property Casualty	'	'
Segment Reporting Information [Line Items]	'	'
Gross written premiums	33,079	25,058
Net written premiums	16,534	7,312
Net earned premiums	12,958	7,879
Lloyd's | Professional Liability	'	'
Segment Reporting Information [Line Items]	'	'
Gross written premiums	14,956	12,892
Net written premiums	9,234	6,263
Net earned premiums	$7,543	$6,073

Reinsurance_Ceded_Additional_I

Reinsurance Ceded - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
	Entity
Effects of Reinsurance [Line Items]	'	'
Ceded premiums earned	$113.60	$110.90
Ceded losses incurred	$53.90	$53.60
Percentage of reinsurance recoverable of 20 largest reinsurers	76.20%	'
Number of largest reinsurers	20	'

Lists_of_20_Largest_Reinsurers

Lists of 20 Largest Reinsurers Measured by Reinsurance Recoverable (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	$246,545		$247,822
Reinsurance Recoverables Paid/Unpaid Losses	872,691		'
Reinsurance Recoverables Total	1,119,236	[1]	'
Collateral Held	205,440	[2]	'
Rating	'AA		'
National Indemnity Company | AM Best, A++ Rating | Standard & Poor's, AA+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	50,635		'
Reinsurance Recoverables Paid/Unpaid Losses	101,575		'
Reinsurance Recoverables Total	152,210	[1]	'
Collateral Held	30,795	[2]	'
Transatlantic Reinsurance Company | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	19,819		'
Reinsurance Recoverables Paid/Unpaid Losses	75,865		'
Reinsurance Recoverables Total	95,684	[1]	'
Collateral Held	6,984	[2]	'
Everest Reinsurance Company | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	21,782		'
Reinsurance Recoverables Paid/Unpaid Losses	70,793		'
Reinsurance Recoverables Total	92,575	[1]	'
Collateral Held	7,706	[2]	'
Munich Reinsurance America Inc. | AM Best, A+ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	5,505		'
Reinsurance Recoverables Paid/Unpaid Losses	68,798		'
Reinsurance Recoverables Total	74,303	[1]	'
Collateral Held	4,510	[2]	'
Swiss Reinsurance America Corporation | AM Best, A+ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	7,690		'
Reinsurance Recoverables Paid/Unpaid Losses	63,942		'
Reinsurance Recoverables Total	71,632	[1]	'
Collateral Held	4,759	[2]	'
Lloyd Syndicate #2003 | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	6,704		'
Reinsurance Recoverables Paid/Unpaid Losses	40,585		'
Reinsurance Recoverables Total	47,289	[1]	'
Collateral Held	5,977	[2]	'
Allied World Reinsurance | AM Best, A Rating | Standard & Poor's, A Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	13,380		'
Reinsurance Recoverables Paid/Unpaid Losses	33,043		'
Reinsurance Recoverables Total	46,423	[1]	'
Collateral Held	3,129	[2]	'
Partner Reinsurance Europe | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	9,483		'
Reinsurance Recoverables Paid/Unpaid Losses	29,208		'
Reinsurance Recoverables Total	38,691	[1]	'
Collateral Held	16,623	[2]	'
Scor Global P&C SE | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	9,690		'
Reinsurance Recoverables Paid/Unpaid Losses	22,199		'
Reinsurance Recoverables Total	31,889	[1]	'
Collateral Held	6,724	[2]	'
Employers Mutual Casualty Company | AM Best, A Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	11,368		'
Reinsurance Recoverables Paid/Unpaid Losses	14,766		'
Reinsurance Recoverables Total	26,134	[1]	'
Collateral Held	10,689	[2]	'
Atlantic Specialty Insurance | AM Best, A Rating | Standard & Poor's, A- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	6,741		'
Reinsurance Recoverables Paid/Unpaid Losses	15,944		'
Reinsurance Recoverables Total	22,685	[1]	'
Collateral Held	839	[2]	'
Tower Insurance Company | AM Best, B Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Paid/Unpaid Losses	21,738		'
Reinsurance Recoverables Total	21,738	[1]	'
Collateral Held	1,803	[2]	'
QBE Reinsurance Corp | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	6,666		'
Reinsurance Recoverables Paid/Unpaid Losses	12,827		'
Reinsurance Recoverables Total	19,493	[1]	'
Collateral Held	1,043	[2]	'
Ace Property and Casualty Insurance Company | AM Best, A++ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	10,108		'
Reinsurance Recoverables Paid/Unpaid Losses	7,884		'
Reinsurance Recoverables Total	17,992	[1]	'
Collateral Held	4,152	[2]	'
Validus Reinsurance Ltd | AM Best, A Rating | Standard & Poor's, A Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	2,316		'
Reinsurance Recoverables Paid/Unpaid Losses	15,198		'
Reinsurance Recoverables Total	17,514	[1]	'
Collateral Held	12,140	[2]	'
Ironshore Indemnity Inc. | AM Best, A Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	7,224		'
Reinsurance Recoverables Paid/Unpaid Losses	10,248		'
Reinsurance Recoverables Total	17,472	[1]	'
Collateral Held	9,273	[2]	'
Lloyd Syndicate #4000 | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	96		'
Reinsurance Recoverables Paid/Unpaid Losses	16,127		'
Reinsurance Recoverables Total	16,223	[1]	'
Collateral Held	111	[2]	'
Odyssey American Reinsurance Corporation | AM Best, A Rating | Standard & Poor's, A- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	3,420		'
Reinsurance Recoverables Paid/Unpaid Losses	12,425		'
Reinsurance Recoverables Total	15,845	[1]	'
Collateral Held	1,545	[2]	'
Berkley Insurance Company | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	2,096		'
Reinsurance Recoverables Paid/Unpaid Losses	11,846		'
Reinsurance Recoverables Total	13,942	[1]	'
AXIS Re Europe | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	4,108		'
Reinsurance Recoverables Paid/Unpaid Losses	9,453		'
Reinsurance Recoverables Total	13,561	[1]	'
Collateral Held	3,724	[2]	'
Insurance Companies	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	198,831		'
Reinsurance Recoverables Paid/Unpaid Losses	654,464		'
Reinsurance Recoverables Total	853,295	[1]	'
Collateral Held	132,526	[2]	'
All Other	'		'
Ceded Credit Risk [Line Items]	'		'
Reinsurance Recoverables Unearned Premium	47,714		'
Reinsurance Recoverables Paid/Unpaid Losses	218,227		'
Reinsurance Recoverables Total	265,941	[1]	'
Collateral Held	$72,914	[2]	'
AM Best | National Indemnity Company | AM Best, A++ Rating | Standard & Poor's, AA+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A++		'
AM Best | Transatlantic Reinsurance Company | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Everest Reinsurance Company | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
AM Best | Munich Reinsurance America Inc. | AM Best, A+ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
AM Best | Swiss Reinsurance America Corporation | AM Best, A+ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
AM Best | Lloyd Syndicate #2003 | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Allied World Reinsurance | AM Best, A Rating | Standard & Poor's, A Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Partner Reinsurance Europe | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
AM Best | Scor Global P&C SE | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Employers Mutual Casualty Company | AM Best, A Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Atlantic Specialty Insurance | AM Best, A Rating | Standard & Poor's, A- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Tower Insurance Company | AM Best, B Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'B		'
AM Best | QBE Reinsurance Corp | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Ace Property and Casualty Insurance Company | AM Best, A++ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A++		'
AM Best | Validus Reinsurance Ltd | AM Best, A Rating | Standard & Poor's, A Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Ironshore Indemnity Inc. | AM Best, A Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Lloyd Syndicate #4000 | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Odyssey American Reinsurance Corporation | AM Best, A Rating | Standard & Poor's, A- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
AM Best | Berkley Insurance Company | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
AM Best | AXIS Re Europe | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | National Indemnity Company | AM Best, A++ Rating | Standard & Poor's, AA+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'AA+		'
Standard & Poor's | Transatlantic Reinsurance Company | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | Everest Reinsurance Company | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | Munich Reinsurance America Inc. | AM Best, A+ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'AA-		'
Standard & Poor's | Swiss Reinsurance America Corporation | AM Best, A+ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'AA-		'
Standard & Poor's | Lloyd Syndicate #2003 | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | Allied World Reinsurance | AM Best, A Rating | Standard & Poor's, A Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
Standard & Poor's | Partner Reinsurance Europe | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | Scor Global P&C SE | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | Employers Mutual Casualty Company | AM Best, A Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'NR		'
Standard & Poor's | Atlantic Specialty Insurance | AM Best, A Rating | Standard & Poor's, A- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A-		'
Standard & Poor's | Tower Insurance Company | AM Best, B Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'NR		'
Standard & Poor's | QBE Reinsurance Corp | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | Ace Property and Casualty Insurance Company | AM Best, A++ Rating | Standard & Poor's, AA- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'AA-		'
Standard & Poor's | Validus Reinsurance Ltd | AM Best, A Rating | Standard & Poor's, A Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A		'
Standard & Poor's | Ironshore Indemnity Inc. | AM Best, A Rating | Standard & Poor's, Not Rated	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'NR		'
Standard & Poor's | Lloyd Syndicate #4000 | AM Best, A Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | Odyssey American Reinsurance Corporation | AM Best, A Rating | Standard & Poor's, A- Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A-		'
Standard & Poor's | Berkley Insurance Company | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
Standard & Poor's | AXIS Re Europe | AM Best, A+ Rating | Standard & Poor's, A+ Rating	'		'
Ceded Credit Risk [Line Items]	'		'
Rating	'A+		'
[1]	Net of reserve for uncollectible reinsurance of approximately $11.3 million.
[2]	Collateral of $205.4 million consists of $145.9 million in ceded balances payable, $53.4 million in letters of credit, and $6.1 million of other balances held by the Company's Insurance Companies and Lloyd's Operations.

Lists_of_20_Largest_Reinsurers1

Lists of 20 Largest Reinsurers Measured by Reinsurance Recoverable (Parenthetical) (Detail) (USD $)	Mar. 31, 2014
Ceded Credit Risk [Line Items]	'
Reserve for uncollectible reinsurance amount	$11,300,000
Collateral Held	205,440,000	[1]
Ceded Balances Payable	'
Ceded Credit Risk [Line Items]	'
Collateral Held	145,900,000
Letter of Credit	'
Ceded Credit Risk [Line Items]	'
Collateral Held	53,400,000
All Other	'
Ceded Credit Risk [Line Items]	'
Collateral Held	$6,100,000
[1]	Collateral of $205.4 million consists of $145.9 million in ceded balances payable, $53.4 million in letters of credit, and $6.1 million of other balances held by the Company's Insurance Companies and Lloyd's Operations.

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014
Maximum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Options expiration term (in years)	'10 years
Options and Non Performance Based Grants | Minimum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share based payment award, award vesting period	'3 years
Options and Non Performance Based Grants | Maximum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share based payment award, award vesting period	'4 years
Non Performance Based Shares	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share based payment award, award vesting period	'5 years
Non Performance Based Shares | Year Three	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	33.33%
Non Performance Based Shares | Year Four	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	33.33%
Non Performance Based Shares | Year Five	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	33.33%
Restricted Stock Units Issued in 2014 and After	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share based payment award, award vesting period	'3 years
Percentage of remaining shares vesting over the period dependent on compound annual growth book value per share immediately prior to vesting date	100.00%
Restricted Stock Units Issued in 2014 and After | Minimum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	50.00%
Restricted Stock Units Issued in 2014 and After | Maximum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	150.00%
Restricted Stock Units Issued between 2011 - 2013	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share based payment award, award vesting period	'3 years
Percentage of shares vesting over the period	50.00%
Percentage of remaining shares vesting over the period dependent on compound annual growth book value per share immediately prior to vesting date	50.00%
Restricted Stock Units Issued between 2011 - 2013 | Minimum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	0.00%
Restricted Stock Units Issued between 2011 - 2013 | Maximum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	150.00%
Performance Based Shares Issued Prior to 2011	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Share based payment award, award vesting period	'5 years
Performance Based Shares Issued Prior to 2011 | Year Three	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	33.33%
Performance Based Shares Issued Prior to 2011 | Year Four	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	33.33%
Performance Based Shares Issued Prior to 2011 | Year Five	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	33.33%
Performance Based Shares Issued Prior to 2011 | Minimum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	0.00%
Performance Based Shares Issued Prior to 2011 | Maximum	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Percentage of shares vesting over the period	150.00%

Amounts_Charged_to_Expense_for

Amounts Charged to Expense for Stock-based Compensation (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'
Stock based compensation	$2,060		$1,467
Restricted stock units	'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'
Stock based compensation	1,886		1,358
Directors restricted stock grants	'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'
Stock based compensation	100	[1]	100	[1]
Employee stock purchase plan	'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'
Stock based compensation	$74		$9
[1]	Relates to non-employee directors serving on the Parent Company's Board of Directors, all of whom have been elected by the Company's stockholders, as well as non-employee directors serving on NUAL's Board of Directors.

Lloyds_Syndicate_1221_Addition

Lloyd's Syndicate 1221 - Additional Information (Detail) (Lloyd's, Syndicate 1221)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
	USD ($)	GBP (£)	USD ($)	GBP (£)
Supplementary Insurance Information, by Segment [Line Items]	'	'	'	'	'	'
Syndicate 1221's stamp capacity	$359.10	£ 215	$323.70	£ 195	'	'
Percentage control of stamp capacity	100.00%	100.00%	'	'	100.00%	100.00%
Pre-tax gain in connection with a change in functional currency	10	'	'	'	'	'
After-tax gain in connection with a change in functional currency	6.6	'	'	'	'	'
Letters of credit	152.1	'	'	'	'	'
Cash collateral posted	$1	'	'	'	'	'

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Income Taxes [Line Items]	'	'	'
Undistributed earnings of non-U.S. subsidiaries	$21,400,000	'	'
Taxes payable on undistributed earnings	2,200,000	'	'
Income tax (benefit) expense	13,354,000	6,643,000	'
Effective income tax rate	32.30%	32.30%	'
Deferred Tax Assets: State and Local	400,000	'	600,000
State and local net operating loss carry-forwards	$100,000	'	$100,000
United Kingdom	'	'	'
Income Taxes [Line Items]	'	'	'
Foreign effective income tax rate	35.00%	'	'
United Kingdom | Syndicate 1221 | Maximum	'	'	'
Income Taxes [Line Items]	'	'	'
Percentage of premiums	50.00%	'	'
United Kingdom | Syndicate 1221 | Minimum	'	'	'
Income Taxes [Line Items]	'	'	'
Foreign effective income tax rate	35.00%	'	'
United States	'	'	'
Income Taxes [Line Items]	'	'	'
U.S. tax rate	35.00%	'	'
State and Local Jurisdiction | Maximum	'	'	'
Income Taxes [Line Items]	'	'	'
State and local tax carry-forwards expiration year	'2032	'	'
State and Local Jurisdiction | Minimum	'	'	'
Income Taxes [Line Items]	'	'	'
State and local tax carry-forwards expiration year	'2024	'	'

Senior_Note_Due_May_1_2016_Add

Senior Note Due May 1, 2016 - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended
	Oct. 04, 2013	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]	'	'	'
Interest expense	'	3,852,000	$2,051,000
Senior Notes	'	'	'
Debt Instrument [Line Items]	'	'	'
Unamortized discount	'	1,700,000	'
Interest expense	'	3,900,000	'
Senior Notes | 5.75% Senior Notes	'	'	'
Debt Instrument [Line Items]	'	'	'
Principal amount of senior notes	265,000,000	'	'
Interest rate stated on senior notes	5.75%	'	'
Senior notes due date	15-Oct-23	'	'
Net proceeds from issuance of senior notes	263,000,000	'	'
Outstanding principal amount of senior notes	'	263,300,000	'
Fair value of senior notes	'	286,700,000	'
Effective interest rate related to senior notes	'	5.86%	'
Debt instrument, covenant compliance	'	'As of March 31, 2014, the Company was in compliance with all such covenants.	'
Senior Notes | 5.75% Senior Notes | Semi Annual Payment, First Payment	'	'	'
Debt Instrument [Line Items]	'	'	'
Interest payment date on senior notes	'	'--04-15	'
Senior Notes | 5.75% Senior Notes | Semi Annual Payment, Second Payment	'	'	'
Debt Instrument [Line Items]	'	'	'
Interest payment date on senior notes	'	'--10-15	'
Senior Notes | 7.0 % Senior Notes	'	'	'
Debt Instrument [Line Items]	'	'	'
Interest rate stated on senior notes	'	7.00%	'
Senior notes due date	'	1-May-16	'
Call premium on redemption of Senior Notes	17,900,000	'	'
Interest expense on senior notes	'	'	$2,000,000

Commitment_and_Contingencies_A

Commitment and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013
Loss Contingencies [Line Items]	'	'	'
Incentive awarded to the company by the State of Connecticut, total	$11.50	'	'
Incentive awarded to the company by the State of Connecticut, non-interest bearing loans	8	'	'
Incentive awarded to the company by the State of Connecticut, grants	3.5	'	'
Non-interest bearing incentive loan term	'10 years	'	'
Incentive awarded to the company by the State of Connecticut, revenue recognized	0.3	'	'
Incentive awarded to the company by the State of Connecticut, deferred revenue	$6.90	$7.20	$7.50

Cash_and_Investments_Including

Cash and Investments Including Other-Than-Temporarily Impaired Securities Recognized within Accumulated Other Comprehensive Income (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Gain (Loss) on Investments [Line Items]	'	'
Total investments	$2,326,240	$2,191,827
Total investments and cash	2,589,124	2,574,586
Gross Unrealized Gains	75,381	69,554
Gross Unrealized Losses	-19,991	-33,530
Amortized Cost	2,533,734	2,538,562
Short-term investments	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments and cash	207,843	296,250
Amortized Cost	207,843	296,250
Cash	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments and cash	55,041	86,509
Amortized Cost	55,041	86,509
Fixed maturities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	2,162,713	2,047,873
Gross Unrealized Gains	47,940	43,854
Gross Unrealized Losses	-18,719	-32,980
Amortized Cost	2,133,492	2,036,999
Fixed maturities | U.S. Treasury bonds, agency bonds, and foreign	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	417,942	441,685
Gross Unrealized Gains	3,066	2,854
Gross Unrealized Losses	-4,956	-8,855
Amortized Cost	419,832	447,686
Fixed maturities | States, municipalities and political subdivisions	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	491,598	460,422
Gross Unrealized Gains	12,216	9,298
Gross Unrealized Losses	-6,948	-13,651
Amortized Cost	486,330	464,775
Fixed maturities | Agency mortgage-backed securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	265,818	301,274
Gross Unrealized Gains	7,182	6,779
Gross Unrealized Losses	-3,525	-6,016
Amortized Cost	262,161	300,511
Fixed maturities | Residential Mortgage Backed Securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	57,852	41,755
Gross Unrealized Gains	1,573	1,212
Gross Unrealized Losses	-136	-161
Amortized Cost	56,415	40,704
Fixed maturities | Asset-backed securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	162,226	125,133
Gross Unrealized Gains	639	653
Gross Unrealized Losses	-563	-480
Amortized Cost	162,150	124,960
Fixed maturities | Commercial mortgage-backed securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	173,333	172,750
Gross Unrealized Gains	7,792	7,656
Gross Unrealized Losses	-272	-374
Amortized Cost	165,813	165,468
Fixed maturities | Mortgage-backed and asset-backed securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	659,229	640,912
Gross Unrealized Gains	17,186	16,300
Gross Unrealized Losses	-4,496	-7,031
Amortized Cost	646,539	631,643
Fixed maturities | Corporate bonds	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	593,944	504,854
Gross Unrealized Gains	15,472	15,402
Gross Unrealized Losses	-2,319	-3,443
Amortized Cost	580,791	492,895
Equity Securities | Common Stock	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	141,476	143,954
Gross Unrealized Gains	26,589	25,700
Gross Unrealized Losses	-1,271	-550
Amortized Cost	116,158	118,804
Equity Securities | Preferred Stock	'	'
Gain (Loss) on Investments [Line Items]	'	'
Total investments	22,051	'
Gross Unrealized Gains	852	'
Gross Unrealized Losses	-1	'
Amortized Cost	$21,200	'

Investments_Additional_Informa

Investments - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]	'	'
Non-credit OTTI on fixed maturities in an unrealized gain position	$600,000	$500,000
Equity Securities | Maximum	'	'
Schedule of Investments [Line Items]	'	'
Percentage of fair value under carrying value	80.00%	'
Mortgage-backed and asset-backed securities	'	'
Schedule of Investments [Line Items]	'	'
Securities, effective maturities	'4 years 1 month 6 days	'
Non-government backed securities	'	'
Schedule of Investments [Line Items]	'	'
Gross Unrealized Loss	$600,000	$1,100,000
Non-government backed securities | Maximum	'	'
Schedule of Investments [Line Items]	'	'
Percentage of investment	5.00%	5.00%

Scheduled_Maturity_Dates_for_F

Scheduled Maturity Dates for Fixed Maturity Securities by Number of Years Until Maturity (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value	'	'
Due in one year or less	$78,570	'
Due after one year through five years	739,594	'
Due after five years through ten years	407,558	'
Due after ten years	277,762	'
Mortgage- and asset-backed securities	659,229	'
Total	2,162,713	2,047,873
Amortized Cost	'	'
Due in one year or less	77,743	'
Due after one year through five years	725,355	'
Due after five years through ten years	406,355	'
Due after ten years	277,500	'
Mortgage- and asset-backed securities	646,539	'
Total	$2,133,492	$2,036,999

Amount_and_Percentage_of_Fixed

Amount and Percentage of Fixed Maturities by Rating (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Investment Securities [Line Items]	'	'
Rating	'AA	'
Fair Value	$2,162,713	$2,047,873
Percent of Total	100.00%	'
Extremely strong	'	'
Investment Securities [Line Items]	'	'
Rating	'AAA	'
Fair Value	389,209	'
Percent of Total	18.00%	'
Very strong	'	'
Investment Securities [Line Items]	'	'
Rating	'AA	'
Fair Value	1,014,656	'
Percent of Total	47.00%	'
Strong	'	'
Investment Securities [Line Items]	'	'
Rating	'A	'
Fair Value	561,731	'
Percent of Total	26.00%	'
Adequate	'	'
Investment Securities [Line Items]	'	'
Rating	'BBB	'
Fair Value	175,311	'
Percent of Total	8.00%	'
Speculative	'	'
Investment Securities [Line Items]	'	'
Rating	'BB & Below	'
Fair Value	18,287	'
Percent of Total	1.00%	'
Not rated	'	'
Investment Securities [Line Items]	'	'
Rating	'NR	'
Fair Value	$3,519	'
Percent of Total	0.00%	'

Summary_of_Aggregate_Fair_Valu

Summary of Aggregate Fair Value and Gross Unrealized Loss by Length of Time Securities had Continuously been in Gross Unrealized Loss Position as Well as Number of Securities (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Investment	Investment
Fixed maturities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	313	405
Fair Value	$899,012	$934,607
Gross Unrealized Loss	18,719	32,980
Fixed maturities | U.S. Treasury bonds, agency bonds, and foreign	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	42	53
Fair Value	249,442	285,730
Gross Unrealized Loss	4,956	8,855
Fixed maturities | U.S. Treasury bonds, agency bonds, and foreign | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	20	27
Fair Value	120,036	136,360
Gross Unrealized Loss	518	1,096
Fixed maturities | U.S. Treasury bonds, agency bonds, and foreign | 7-12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	21	26
Fair Value	128,509	149,370
Gross Unrealized Loss	4,426	7,759
Fixed maturities | U.S. Treasury bonds, agency bonds, and foreign | > 12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	1	'
Fair Value	897	'
Gross Unrealized Loss	12	'
Fixed maturities | States, municipalities and political subdivisions	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	107	138
Fair Value	221,178	257,641
Gross Unrealized Loss	6,948	13,651
Fixed maturities | States, municipalities and political subdivisions | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	14	28
Fair Value	24,744	40,132
Gross Unrealized Loss	163	297
Fixed maturities | States, municipalities and political subdivisions | 7-12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	77	104
Fair Value	160,382	205,152
Gross Unrealized Loss	5,050	12,100
Fixed maturities | States, municipalities and political subdivisions | > 12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	16	6
Fair Value	36,052	12,357
Gross Unrealized Loss	1,735	1,254
Fixed maturities | Agency mortgage-backed securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	70	112
Fair Value	106,539	140,102
Gross Unrealized Loss	3,525	6,016
Fixed maturities | Agency mortgage-backed securities | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	6	39
Fair Value	22,200	39,458
Gross Unrealized Loss	65	434
Fixed maturities | Agency mortgage-backed securities | 7-12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	53	64
Fair Value	61,847	77,860
Gross Unrealized Loss	2,060	3,768
Fixed maturities | Agency mortgage-backed securities | > 12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	11	9
Fair Value	22,492	22,784
Gross Unrealized Loss	1,400	1,814
Fixed maturities | Residential Mortgage Backed Securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	19	25
Fair Value	3,655	3,848
Gross Unrealized Loss	136	161
Fixed maturities | Residential Mortgage Backed Securities | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	2	3
Fair Value	897	431
Gross Unrealized Loss	3	2
Fixed maturities | Residential Mortgage Backed Securities | 7-12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	4	7
Fair Value	536	950
Gross Unrealized Loss	18	29
Fixed maturities | Residential Mortgage Backed Securities | > 12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	13	15
Fair Value	2,222	2,467
Gross Unrealized Loss	115	130
Fixed maturities | Asset-backed securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	10	15
Fair Value	73,708	76,090
Gross Unrealized Loss	563	480
Fixed maturities | Asset-backed securities | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	7	14
Fair Value	42,213	75,887
Gross Unrealized Loss	67	479
Fixed maturities | Asset-backed securities | 7-12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	3	1
Fair Value	31,495	203
Gross Unrealized Loss	496	1
Fixed maturities | Commercial mortgage-backed securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	7	10
Fair Value	21,626	22,584
Gross Unrealized Loss	272	374
Fixed maturities | Commercial mortgage-backed securities | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	3	4
Fair Value	6,103	6,712
Gross Unrealized Loss	13	31
Fixed maturities | Commercial mortgage-backed securities | 7-12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	2	2
Fair Value	15,004	15,098
Gross Unrealized Loss	250	322
Fixed maturities | Commercial mortgage-backed securities | > 12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	2	4
Fair Value	519	774
Gross Unrealized Loss	9	21
Fixed maturities | Corporate bonds	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	58	52
Fair Value	222,864	148,612
Gross Unrealized Loss	2,319	3,443
Fixed maturities | Corporate bonds | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	45	34
Fair Value	176,120	93,591
Gross Unrealized Loss	744	717
Fixed maturities | Corporate bonds | 7-12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	12	18
Fair Value	45,043	55,021
Gross Unrealized Loss	1,575	2,726
Fixed maturities | Corporate bonds | > 12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	1	'
Fair Value	1,701	'
Common Stock	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	13	7
Fair Value	25,372	10,925
Gross Unrealized Loss	1,271	550
Common Stock | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	10	5
Fair Value	21,578	7,387
Gross Unrealized Loss	1,120	422
Common Stock | 7-12 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	3	2
Fair Value	3,794	3,538
Gross Unrealized Loss	151	128
Preferred Stock	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	1	'
Fair Value	553	'
Gross Unrealized Loss	1	'
Preferred Stock | 0-6 months	'	'
Gain (Loss) on Investments [Line Items]	'	'
Number of Securities	1	'
Fair Value	553	'
Gross Unrealized Loss	$1	'

Summary_of_Activity_Related_to

Summary of Activity Related to Other-Than-Temporary Impairment Losses (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
		Investment
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'
Number of Securities	'	2
Total other-than-temporary impairment losses	'	$42
Portion of loss recognized in other comprehensive income	'	'
Net other-than-temporary impairment losses recognized in earnings	'	42
Corporate And Other Bonds	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'
Portion of loss recognized in other comprehensive income	'	'
Commercial mortgage-backed securities	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'
Portion of loss recognized in other comprehensive income	'	'
Residential Mortgage Backed Securities	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'
Portion of loss recognized in other comprehensive income	'	'
Asset-backed securities	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'
Portion of loss recognized in other comprehensive income	'	'
Equity Securities	'	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'
Number of Securities	'	2
Total other-than-temporary impairment losses	'	42
Portion of loss recognized in other comprehensive income	'	'
Net other-than-temporary impairment losses recognized in earnings	'	$42

Summary_of_Cumulative_Amounts_

Summary of Cumulative Amounts Related to Credit Loss Portion of Other-Than-Temporary Impairment Losses on Debt Securities (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'	'
Beginning balance	$4,183	$2,362
Additions for credit loss impairments recognized in the current period on securities not previously impaired	'	'
Additions for credit loss impairments recognized in the current period on securities previously impaired	'	'
Reductions for credit loss impairments previously recognized on securities sold during the period	'	'
Ending balance	$4,183	$2,362

Contractual_Maturity_by_Number

Contractual Maturity by Number of Years Until Maturity for Fixed Maturity Securities with Gross Unrealized Loss (Detail) (Fixed maturities, USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Gross Unrealized Loss Amount	$18,719	$32,980
Percent of Total Gross Unrealized Loss	100.00%	'
Fair Value Amount	899,012	934,607
Percent of Total Fair Value	100.00%	'
Due in one year or less	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Percent of Total Gross Unrealized Loss	0.00%	'
Fair Value Amount	1,701	'
Percent of Total Fair Value	0.00%	'
Due After One Year Through Five Years	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Gross Unrealized Loss Amount	1,697	'
Percent of Total Gross Unrealized Loss	9.00%	'
Fair Value Amount	316,024	'
Percent of Total Fair Value	35.00%	'
Due After Five Years Through Ten Years	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Gross Unrealized Loss Amount	7,773	'
Percent of Total Gross Unrealized Loss	41.00%	'
Fair Value Amount	235,549	'
Percent of Total Fair Value	26.00%	'
Due After Ten Years	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Gross Unrealized Loss Amount	4,753	'
Percent of Total Gross Unrealized Loss	26.00%	'
Fair Value Amount	140,210	'
Percent of Total Fair Value	16.00%	'
Mortgage- and asset-backed securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Gross Unrealized Loss Amount	4,496	'
Percent of Total Gross Unrealized Loss	24.00%	'
Fair Value Amount	$205,528	'
Percent of Total Fair Value	23.00%	'

Net_Investment_Income_Detail

Net Investment Income (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Net Investment Income [Line Items]	'	'
Investment Income	$17,404	$14,386
Investment expenses	-794	-729
Net investment income	16,610	13,657
Fixed maturities	'	'
Net Investment Income [Line Items]	'	'
Investment Income	13,953	13,167
Equity Securities	'	'
Net Investment Income [Line Items]	'	'
Investment Income	3,233	1,030
Short-term investments	'	'
Net Investment Income [Line Items]	'	'
Investment Income	$218	$189

Change_in_Net_Unrealized_Gains

Change in Net Unrealized Gains and Losses (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Gross unrealized gains (losses)	$19,366	($2,758)
Deferred income tax	6,675	-1,003
Change in net unrealized gains (losses), net	12,691	-1,755
Fixed maturities	'	'
Gross unrealized gains (losses)	18,347	-10,930
Equity Securities	'	'
Gross unrealized gains (losses)	$1,019	$8,172

Realized_Gains_and_Losses_Excl

Realized Gains and Losses Excluding Net Other-Than-Temporary Impairment Losses Recognized in Earnings (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Gain (Loss) on Investments [Line Items]	'	'
Net realized gains (losses)	$833	$4,814
Fixed maturities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Gains	1,867	3,206
Losses	-2,051	-310
Net realized gains (losses)	-184	2,896
Equity Securities	'	'
Gain (Loss) on Investments [Line Items]	'	'
Gains	1,920	1,918
Losses	-903	'
Net realized gains (losses)	$1,017	$1,918

Fixed_Maturities_and_Equity_Se

Fixed Maturities and Equity Securities by Asset Class that are Measured at Fair Value (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	$2,326,240	$2,191,827
Fixed maturities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	2,162,713	2,047,873
Fixed maturities | U.S. Treasury bonds, agency bonds, and foreign	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	417,942	441,685
Fixed maturities | States, municipalities and political subdivisions	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	491,598	460,422
Fixed maturities | Agency mortgage-backed securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	265,818	301,274
Fixed maturities | Residential Mortgage Backed Securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	57,852	41,755
Fixed maturities | Asset-backed securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	162,226	125,133
Fixed maturities | Commercial mortgage-backed securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	173,333	172,750
Fixed maturities | Mortgage-backed and asset-backed securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	659,229	640,912
Fixed maturities | Corporate bonds	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	593,944	504,854
Equity Securities | Common Stock	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	141,476	143,954
Equity Securities | Preferred Stock	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	22,051	'
Level 1	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	359,107	386,333
Level 1 | Fixed maturities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	217,631	242,379
Level 1 | Fixed maturities | U.S. Treasury bonds, agency bonds, and foreign	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	217,631	242,379
Level 1 | Equity Securities | Common Stock	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	141,476	143,954
Level 2	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	1,967,133	1,801,087
Level 2 | Fixed maturities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	1,945,082	1,801,087
Level 2 | Fixed maturities | U.S. Treasury bonds, agency bonds, and foreign	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	200,311	199,306
Level 2 | Fixed maturities | States, municipalities and political subdivisions	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	491,598	460,422
Level 2 | Fixed maturities | Agency mortgage-backed securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	265,818	301,274
Level 2 | Fixed maturities | Residential Mortgage Backed Securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	57,852	41,755
Level 2 | Fixed maturities | Asset-backed securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	162,226	125,133
Level 2 | Fixed maturities | Commercial mortgage-backed securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	173,333	172,750
Level 2 | Fixed maturities | Mortgage-backed and asset-backed securities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	659,229	640,912
Level 2 | Fixed maturities | Corporate bonds	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	593,944	500,447
Level 2 | Equity Securities | Preferred Stock	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	22,051	'
Level 3	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	'	4,407
Level 3 | Fixed maturities	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	'	4,407
Level 3 | Fixed maturities | Corporate bonds	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed maturities and equity securities, at fair Value	'	$4,407

Reconciliation_of_Beginning_an

Reconciliation of Beginning and Ending Balances for all Investments Measured at Fair Value Using Level 3 Inputs (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'
Beginning Balance	$4,407
Realized Gains (Losses)	'
Unrealized Gains (Losses)	'
Purchases	'
Sales	'
Settlements	'
Transfers into Level 3	'
Transfers out of Level 3	-4,407
Corporate bonds	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'
Beginning Balance	4,407
Realized Gains (Losses)	'
Unrealized Gains (Losses)	'
Purchases	'
Sales	'
Settlements	'
Transfers into Level 3	'
Transfers out of Level 3	($4,407)

Credit_Facility_Additional_Inf

Credit Facility - Additional Information (Detail) (USD $)	3 Months Ended			0 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 28, 2011	Mar. 31, 2014	Nov. 22, 2012
			Lloyd's	Amended and Restated Credit Agreement
			Syndicate 1221
Line of Credit Facility [Line Items]	'	'	'	'
Line of credit facility	'	$165	'	$165
Issuance of new letters of credit, expiry date	'	'	'	31-Dec-14
Aggregate face amount of letters of credit outstanding	'	'	152.1	'
Cash collateral posted	'	'	$1	'
Line of credit facility, covenant terms	'This credit facility contains customary covenants for facilities of this type, including restrictions on indebtedness and liens, limitations on mergers, dividends and the sale of assets, and requirements as to maintaining certain consolidated tangible net worth, statutory surplus and other financial ratios. The credit facility also provides for customary events of default, including failure to pay principal, interest or fees when due, failure to comply with covenants, any representation or warranty made by the Company being false in any material respect, default under certain other indebtedness, certain insolvency or receivership events affecting the Company and its subsidiaries, the occurrence of certain material judgments, or a change in control of the Company.	'	'	'
Line of credit facility, covenant compliance	'The Company was in compliance with all covenants under the credit facility as of March 31, 2014.	'	'	'