W. R. Berkley (WRB) 10-Q 7 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Informatio

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Aug. 01, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	BERKLEY W R CORP
Entity Central Index Key	11,544
Current Fiscal Year End Date	--06-30
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		121,277,042

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Investments:
Fixed maturity securities	$ 13,514,085	$ 13,190,668
Investment funds	1,190,963	1,198,146
Real estate	1,317,089	1,184,981
Arbitrage trading account	634,016	299,999
Equity securities available for sale	612,807	669,200
Loans receivable	96,064	106,798
Total investments	17,365,024	16,649,792
Cash and cash equivalents	788,354	795,285
Premiums and fees receivable	1,867,048	1,701,854
Due from reinsurers	1,646,587	1,743,980
Deferred policy acquisition costs	539,961	537,890
Prepaid reinsurance premiums	482,258	413,140
Trading account receivables from brokers and clearing organizations	164,696	484,593
Property, furniture and equipment	424,984	349,432
Goodwill	144,913	144,513
Accrued investment income	136,663	127,047
Other assets	433,003	402,550
Total assets	23,993,491	23,350,076
Liabilities:
Reserves for losses and loss expenses	11,324,267	11,197,195
Unearned premiums	3,425,534	3,283,300
Due to reinsurers	221,633	213,128
Trading account securities sold but not yet purchased	62,860	51,179
Federal and foreign income taxes	94,887	119,597
Other liabilities	1,051,322	916,318
Senior notes and other debt	1,759,115	1,760,595
Subordinated debentures	727,924	727,630
Total liabilities	18,667,542	18,268,942
Equity:
Authorized 5,000,000 shares; issued and outstanding - none	0	0
Authorized 500,000,000 shares, issued and outstanding, net of treasury shares, 121,271,028 and 121,193,599 shares, respectively	47,024	47,024
Additional paid-in capital	1,057,939	1,037,446
Retained earnings	6,735,066	6,595,987
Accumulated other comprehensive income	133,302	55,568
Treasury stock, at cost, 113,846,890 and 113,924,319 shares, respectively	2,686,813	2,688,817
Total stockholders’ equity	5,286,518	5,047,208
Noncontrolling interests	39,431	33,926
Total equity	5,325,949	5,081,134
Total liabilities and equity	$ 23,993,491	$ 23,350,076

Consolidated Balance Sheets Co3

Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollar per share)	$ 0.1	$ 0.1
Preferred shares authorized	5,000,000	5,000,000
Preferred shares issued	0	0
Preferred shares outstanding	0	0
Common stock, par value (in dollar per share)	$ 0.2	$ 0.2
Common shares authorized	500,000,000	500,000,000
Common shares issued	121,271,028	121,193,599
Common shares outstanding	121,271,028	121,193,599
Treasury stock issued at cost	113,846,890	113,924,319

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
REVENUES:
Net premiums written	$ 1,564,251	$ 1,642,569	$ 3,211,089	$ 3,306,291
Change in net unearned premiums	4,452	(82,776)	(72,345)	(219,163)
Net premiums earned	1,568,703	1,559,793	3,138,744	3,087,128
Net investment income	135,264	129,049	284,123	259,182
Net realized investment gains	40,453	6,315	92,801	31,772
Other-than-temporary impairments	0	0	0	(18,114)
Insurance service fees	33,584	36,939	66,864	77,301
Revenues from non-insurance businesses	69,857	123,764	135,247	225,544
Other income	188	54	688	312
Total revenues	1,848,049	1,855,914	3,718,467	3,663,125
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	964,698	964,162	1,944,302	1,886,483
Other operating costs and expenses	616,632	581,955	1,220,332	1,164,414
Expenses from non-insurance businesses	68,959	116,731	134,978	212,262
Interest expense	36,799	34,752	73,597	66,976
Total operating costs and expenses	1,687,088	1,697,600	3,373,209	3,330,135
Income before income taxes	160,961	158,314	345,258	332,990
Income tax expense	(51,388)	(49,408)	(111,011)	(103,837)
Net income before noncontrolling interests	109,573	108,906	234,247	229,153
Noncontrolling interests	(569)	61	(1,796)	(676)
Net income to common stockholders	$ 109,004	$ 108,967	$ 232,451	$ 228,477
NET INCOME PER SHARE:
Basic (in dollar per share)	$ 0.87	$ 0.89	$ 1.88	$ 1.86
Diluted (in dollar per share)	$ 0.85	$ 0.85	$ 1.81	$ 1.78

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) Statement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 109,573	$ 108,906	$ 234,247	$ 229,153
Other comprehensive income:
Change in unrealized currency translation adjustments	20,247	(55,870)	42,982	(57,917)
Change in unrealized investment gains, net of taxes	43,597	105,033	34,766	181,888
Other comprehensive income	63,844	49,163	77,748	123,971
Comprehensive income	173,417	158,069	311,995	353,124
Noncontrolling interests	(602)	56	(1,810)	(667)
Comprehensive income to common stockholders	$ 172,815	$ 158,125	$ 310,185	$ 352,457

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Unaudited) Statement - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated Other Comprehensive Income	Unrealized investment gain	Currency Translation Adjustments	Treasury stock	Noncontrolling interest
Beginning of period at Dec. 31, 2015		$ 47,024	$ 1,005,455	$ 6,178,070		$ 180,695	$ (247,393)	$ (2,563,605)	$ 32,962
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued including tax benefit			(191)
Restricted stock units expensed			16,350
Stock issued			0
Net income before noncontrolling interests	$ 229,153			228,477					676
Dividends				(30,654)
Unrealized gains on securities not other-than-temporarily impaired	181,888					180,714
Unrealized gains on other-than-temporarily impaired securities						1,183
Net change in period	(57,917)						(57,917)
Stock exercised/vested								1,717
Stock repurchased								(37,424)
Stock incentive plans expensed								0
Contributions									2,923
Other comprehensive income (loss), net of tax	123,971				$ 123,971		(57,917)		(9)
End of period at Jun. 30, 2016			1,021,614	6,375,893	57,282	362,592	(305,310)	(2,599,312)	36,552
Beginning of period at Dec. 31, 2016	5,081,134	$ 47,024	1,037,446	6,595,987		427,154	(371,586)	(2,688,817)	33,926
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued including tax benefit			(1,356)
Restricted stock units expensed			20,788
Stock issued			1,061
Net income before noncontrolling interests	234,247			232,451					1,796
Dividends				(93,372)
Unrealized gains on securities not other-than-temporarily impaired	34,766					33,908
Unrealized gains on other-than-temporarily impaired securities						844
Net change in period	42,982						42,982
Stock exercised/vested								1,276
Stock repurchased								0
Stock incentive plans expensed								728
Contributions									3,695
Other comprehensive income (loss), net of tax	77,748				77,748		42,982		14
End of period at Jun. 30, 2017	$ 5,325,949		$ 1,057,939	$ 6,735,066	$ 133,302	$ 461,906	$ (328,604)	$ (2,686,813)	$ 39,431

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 232,451	$ 228,477
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(92,801)	(13,658)
Depreciation and amortization	44,679	46,873
Noncontrolling interests	1,796	676
Investment funds	(35,544)	(35,092)
Stock incentive plans	22,508	17,876
Change in:
Arbitrage trading account	(2,440)	(2,303)
Premiums and fees receivable	(159,827)	(174,811)
Reinsurance accounts	34,985	(100,545)
Deferred policy acquisition costs	(2,236)	(50,578)
Income taxes	(42,626)	8,269
Reserves for losses and loss expenses	101,781	239,621
Unearned premiums	140,399	276,815
Other	(18,267)	(109,302)
Net cash from operating activities	224,858	332,318
CASH USED IN INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	2,069,718	716,674
Proceeds from sale of equity securities	89,340	14,558
Distributions from investment funds	49,594	7,632
Proceeds from maturities and prepayments of fixed maturity securities	888,423	1,191,548
Purchase of fixed maturity securities	(3,164,892)	(2,238,683)
Purchase of equity securities	(787)	(126,414)
Real estate purchased	(109,846)	(114,434)
Change in loans receivable	10,734	130,267
Net additions to property, furniture and equipment	(89,715)	(21,224)
Change in balances due to security brokers	104,463	51,918
Payment for business purchased net of cash aquired	(71,346)	(41,213)
Net cash used in investing activities	(224,314)	(429,371)
CASH (USED IN) FROM FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(1,475)	(38,427)
Net proceeds from issuance of debt	0	388,901
Cash dividends to common stockholders	(15,758)	(30,655)
Purchase of common treasury shares	0	(37,424)
Other, net	(1,260)	(926)
Net cash (used in) from financing activities	(18,493)	281,469
Net impact on cash due to change in foreign exchange rates	11,018	663
Net change in cash and cash equivalents	(6,931)	185,079
Cash and cash equivalents at beginning of year	795,285	763,631
Cash and cash equivalents at end of period	$ 788,354	$ 948,710

General

General	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General The unaudited consolidated financial statements, which include the accounts of W. R. Berkley Corporation and its subsidiaries (the “Company”) have been prepared on the basis of U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all the information and notes required by GAAP for annual financial statements. The unaudited consolidated financial statements reflect all adjustments, consisting only of normal recurring items, which are necessary to present fairly the Company’s financial position and results of operations on a basis consistent with the prior audited consolidated financial statements. Operating results for interim periods are not necessarily indicative of the results that may be expected for the year. All significant intercompany accounts and transactions have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the revenues and expenses reflected during the reporting period. For further information related to a description of areas of judgment and estimates and other information necessary to understand the Company’s financial position and results of operations, refer to the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 . Reclassifications have been made in the 2016 financial statements as originally reported to conform to the presentation of the 2017 financial statements. The income tax provision has been computed based on the Company’s estimated annual effective tax rate. The effective tax rate for the quarter differs from the federal income tax rate of 35% principally because of tax-exempt investment income.

Per Share Data

Per Share Data	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Per Share Data	Per Share Data The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 4,087,731 common shares held in a grantor trust established in March 2017). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units (RSUs). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect. The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows: For the Three Months For the Six Months Ended June 30, Ended June 30, (In thousands) 2017 2016 2017 2016 Basic 125,334 122,616 123,623 122,698 Diluted 128,601 128,575 128,546 128,562

Recent Accounting Pronouncement

Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently adopted accounting pronouncements: In May 2015, the FASB issued ASU 2015-09, Disclosures about Short-Duration Contracts. ASU 2015-09 requires companies that issue short duration insurance contracts to disclose additional information, including: (i) incurred and paid claims development tables; (ii) frequency and severity of claims; and (iii) information about material changes in judgments made in calculating the liability for unpaid claim adjustment expenses, including reasons for the change and the effects on the financial statements. The Company adopted this updated guidance on January 1, 2016 with regard to the annual requirements and on January 1, 2017 with regard to the interim requirements. The amendments in ASU 2015-09 are applied retrospectively by providing comparative disclosures for each period presented, except for those requirements that apply only to the current period. As the requirements are disclosure only, the adoption of this guidance did not impact our financial condition or results of operations, but did result in additional disclosures. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 includes provisions intended to simplify various previous provisions related to how share-based payments are accounted for and presented in the financial statements. Under the new guidance, excess tax benefits (deductions for share based payment awards for tax purposes that exceed the compensation cost recognized for financial reporting purposes) are reported within the income tax expense financial statement line item. Previously, excess tax benefits were reported within additional paid in capital. The Company adopted this updated guidance on January 1, 2017 prospectively. The adoption of this guidance did not have a material impact on the Company's financial condition or results of operations. All other accounting and reporting standards that became effective in 2017 were either not applicable to the Company or their adoption did not have a material impact on the Company. Accounting and reporting standards that are not yet effective: In May 2014, the FASB issued ASU 2014-09, Revenue from Customers. ASU 2014-09 clarifies the principles for recognizing revenue. While insurance contracts are not within the scope of this updated guidance, the Company’s insurance service fee revenue and non-insurance business revenue will be subject to this updated guidance. The updated guidance requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. The updated guidance, as amended by ASU 2015-14, is effective for public business entities for annual and interim reporting periods beginning after December 15, 2017. The adoption of this guidance is not expected to have a material effect on the Company’s financial condition or results of operations. In January 2016, the FASB issued ASU 2016-01, Financial Instruments. ASU 2016-01 amends the accounting guidance for financial instruments to require all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The updated guidance is effective for public business entities for annual reporting periods beginning after December 15, 2017 and interim periods within those years. The adoption of this guidance is not expected to have a material effect on the Company’s financial condition upon adoption, but will impact results of operations after adoption of this guidance as unrealized gains and losses on equity securities will no longer be reported directly in accumulated other comprehensive income (AOCI), but will instead be reported in net income. In February 2016, the FASB issued ASU 2016-02, Leases, which amends the accounting and disclosure guidance for leases. This guidance retains the two classifications of a lease, as either an operating or finance lease, both of which will require lessees to recognize a right-of-use asset and a lease liability for leases with terms of more than 12 months. The right-of-use asset and the lease liability will be determined based upon the present value of cash flows. Finance leases will reflect the financial arrangement by recognizing interest expense on the lease liability separately from the amortization expense of the right-of-use asset. Operating leases will recognize lease expense (with no separate recognition of interest expense) on a straight-line basis over the term of the lease. The accounting by lessors is not significantly changed by the updated guidance. The updated guidance is effective for reporting periods beginning after December 15, 2018, and will require that the earliest comparative period presented include the measurement and recognition of existing leases with an adjustment to equity as if the updated guidance had always been applied. The Company is currently evaluating the impact that the adoption of this guidance will have on its results of operations, financial position and liquidity. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses, which amends the accounting guidance for credit losses on financial instruments. The updated guidance amends the current other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. This guidance also applies a new current expected credit loss model for determining credit-related impairments for financial instruments measured at amortized cost. The updated guidance is effective for reporting periods beginning after December 15, 2019. The Company will not be able to determine the impact the adoption of this guidance will have on its results of operations, financial position or liquidity until the year the guidance becomes effective. All other recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.

Acquisitions_Dispositions

Acquisitions/Dispositions	6 Months Ended
	Jun. 30, 2017
Business Combinations [Abstract]
Acquisitions/Dispositions	Acquisitions/Disposition In March 2017, the Company acquired an 89.5% ownership interest for $72.5 million in a company engaged in providing textile solutions world-wide. The fair value of the assets acquired and liabilities assumed have been estimated based on a preliminary valuation. The fair values of the assets and liabilities will be adjusted, as needed, following completion of the final valuation. The following table summarizes the initial estimated fair value of net assets acquired and liabilities assumed for the business combination completed in 2017: (In thousands) 2017 Cash and cash equivalents $ 1,154 Real estate, furniture and equipment 6,434 Goodwill and other intangibles assets 62,406 Other assets 9,417 Total assets acquired 79,411 Other liabilities assumed (1,911 ) Noncontrolling interest (5,000 ) Net assets acquired $ 72,500 In February 2016, the Company acquired an 85% ownership interest for $42.3 million in a company engaged in the distribution of promotional merchandise.

Consolidated Statements of Co12

Consolidated Statements of Comprehensive Income	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Consolidated Statements of Comprehensive Income	Consolidated Statement of Comprehensive Income The following table presents the components of the changes in accumulated other comprehensive income ("AOCI"): (In thousands) Unrealized Investment Gains (Losses) Currency Translation Adjustments Accumulated Other Comprehensive Income As of and for the six months ended June 30, 2017: Changes in AOCI Beginning of period $ 427,154 $ (371,586 ) $ 55,568 Other comprehensive income before reclassifications 89,309 42,982 132,291 Amounts reclassified from AOCI (54,543 ) — (54,543 ) Other comprehensive income 34,766 42,982 77,748 Unrealized investment gain related to non-controlling interest (14 ) — (14 ) End of period $ 461,906 $ (328,604 ) $ 133,302 Amounts reclassified from AOCI Pre-tax $ (83,912 ) (1) $ — $ (83,912 ) Tax effect 29,369 (2) — 29,369 After-tax amounts reclassified $ (54,543 ) $ — $ (54,543 ) Other comprehensive income Pre-tax $ 58,711 $ 42,982 $ 101,693 Tax effect (23,945 ) — (23,945 ) Other comprehensive income $ 34,766 $ 42,982 $ 77,748 As of and for the three months ended June 30, 2017: Changes in AOCI Beginning of period $ 418,342 $ (348,851 ) $ 69,491 Other comprehensive income before reclassifications 69,315 20,247 89,562 Amounts reclassified from AOCI (25,718 ) — (25,718 ) Other comprehensive income 43,597 20,247 63,844 Unrealized investment gain related to non-controlling interest (33 ) — (33 ) End of period $ 461,906 $ (328,604 ) $ 133,302 Amounts reclassified from AOCI Pre-tax $ (39,566 ) (1) $ — $ (39,566 ) Tax effect 13,848 (2) — 13,848 After-tax amounts reclassified $ (25,718 ) $ — $ (25,718 ) Other comprehensive income Pre-tax $ 68,282 $ 20,247 $ 88,529 Tax effect (24,685 ) — (24,685 ) Other comprehensive income $ 43,597 $ 20,247 $ 63,844 _________________________ (1) Net investment gains in the consolidated statements of income. (2) Income tax expense in the consolidated statements of income. (In thousands) Unrealized Investment Gains (Losses) Currency Translation Adjustments Accumulated Other Comprehensive Income As of and for the six months ended June 30, 2016: Changes in AOCI Beginning of period $ 180,695 $ (247,393 ) $ (66,698 ) Other comprehensive income before reclassifications 191,791 (57,917 ) 133,874 Amounts reclassified from AOCI (9,903 ) — (9,903 ) Other comprehensive income 181,888 (57,917 ) 123,971 Unrealized investment losses related to non-controlling interest 9 — 9 End of period $ 362,592 $ (305,310 ) $ 57,282 Amounts reclassified from AOCI Pre-tax $ (15,235 ) (1) $ — $ (15,235 ) Tax effect 5,332 (2) — 5,332 After-tax amounts reclassified $ (9,903 ) $ — $ (9,903 ) Other comprehensive income Pre-tax $ 270,995 $ (57,917 ) $ 213,078 Tax effect (89,107 ) — (89,107 ) Other comprehensive income $ 181,888 $ (57,917 ) $ 123,971 As of and for the three months ended June 30, 2016: Changes in AOCI Beginning of period $ 257,564 $ (249,440 ) $ 8,124 Other comprehensive income before reclassifications 113,549 (55,870 ) 57,679 Amounts reclassified from AOCI (8,516 ) — (8,516 ) Other comprehensive income 105,033 (55,870 ) 49,163 Unrealized investment gain related to non-controlling interest (5 ) — (5 ) End of period $ 362,592 $ (305,310 ) $ 57,282 Amounts reclassified from AOCI Pre-tax $ (13,101 ) (1) $ — $ (13,101 ) Tax effect 4,585 (2) — 4,585 After-tax amounts reclassified $ (8,516 ) $ — $ (8,516 ) Other comprehensive income Pre-tax $ 156,605 $ (55,870 ) $ 100,735 Tax effect (51,572 ) — (51,572 ) Other comprehensive income $ 105,033 $ (55,870 ) $ 49,163 _______________ (1) Net investment gains in the consolidated statements of income. (2) Income tax expense in the consolidated statements of income.

Statements of Cash Flow

Statements of Cash Flow	6 Months Ended
	Jun. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Statements of Cash Flow	Statements of Cash Flow Interest payments were $72,528,000 and $64,109,000 and income taxes paid were $145,123,000 and $86,695,000 in the six months ended June 30, 2017 and 2016 , respectively.

Investments In Fixed Maturity S

Investments In Fixed Maturity Securities	6 Months Ended
	Jun. 30, 2017
Debt securities
Schedule of Available-for-sale Securities [Line Items]
Investments In Fixed Maturity Securities	Investments in Fixed Maturity Securities At June 30, 2017 and December 31, 2016 , investments in fixed maturity securities were as follows: (In thousands) Amortized Cost Gross Unrealized Fair Value Carrying Value Gains Losses June 30, 2017 Held to maturity: State and municipal $ 64,931 $ 14,943 $ — $ 79,874 $ 64,931 Residential mortgage-backed 14,754 1,578 — 16,332 14,754 Total held to maturity 79,685 16,521 — 96,206 79,685 Available for sale: U.S. government and government agency 432,145 13,941 (2,135 ) 443,951 443,951 State and municipal: Special revenue 2,770,582 80,887 (9,471 ) 2,841,998 2,841,998 State general obligation 471,980 21,596 (1,359 ) 492,217 492,217 Pre-refunded 312,535 21,825 (216 ) 334,144 334,144 Corporate backed 384,609 10,609 (916 ) 394,302 394,302 Local general obligation 354,110 26,507 (467 ) 380,150 380,150 Total state and municipal 4,293,816 161,424 (12,429 ) 4,442,811 4,442,811 Mortgage-backed securities: Residential (1) 997,886 13,968 (9,608 ) 1,002,246 1,002,246 Commercial 190,352 566 (1,257 ) 189,661 189,661 Total mortgage-backed securities 1,188,238 14,534 (10,865 ) 1,191,907 1,191,907 Asset-backed 2,196,114 6,529 (10,613 ) 2,192,030 2,192,030 Corporate: Industrial 2,394,374 73,884 (2,717 ) 2,465,541 2,465,541 Financial 1,444,201 49,524 (4,929 ) 1,488,796 1,488,796 Utilities 255,777 12,725 (576 ) 267,926 267,926 Other 48,875 282 (18 ) 49,139 49,139 Total corporate 4,143,227 136,415 (8,240 ) 4,271,402 4,271,402 Foreign 854,298 38,773 (772 ) 892,299 892,299 Total available for sale 13,107,838 371,616 (45,054 ) 13,434,400 13,434,400 Total investments in fixed maturity securities $ 13,187,523 $ 388,137 $ (45,054 ) $ 13,530,606 $ 13,514,085 (In thousands) Amortized Gross Unrealized Fair Carrying Gains Losses December 31, 2016 Held to maturity: State and municipal $ 72,582 $ 12,453 $ — $ 85,035 $ 72,582 Residential mortgage-backed 15,944 1,693 — 17,637 15,944 Total held to maturity 88,526 14,146 — 102,672 88,526 Available for sale: U.S. government and government agency 496,187 20,208 (2,593 ) 513,802 513,802 State and municipal: Special revenue 2,791,211 58,559 (26,315 ) 2,823,455 2,823,455 State general obligation 524,682 16,964 (5,139 ) 536,507 536,507 Pre-refunded 356,535 19,181 (165 ) 375,551 375,551 Corporate backed 410,933 6,172 (6,452 ) 410,653 410,653 Local general obligation 360,022 15,682 (2,367 ) 373,337 373,337 Total state and municipal 4,443,383 116,558 (40,438 ) 4,519,503 4,519,503 Mortgage-backed securities: Residential (1) 1,034,301 15,431 (12,950 ) 1,036,782 1,036,782 Commercial 155,540 304 (2,981 ) 152,863 152,863 Total mortgage-backed securities 1,189,841 15,735 (15,931 ) 1,189,645 1,189,645 Asset-backed 1,913,830 5,971 (11,941 ) 1,907,860 1,907,860 Corporate: Industrial 2,315,567 71,007 (7,174 ) 2,379,400 2,379,400 Financial 1,369,001 39,543 (11,270 ) 1,397,274 1,397,274 Utilities 229,154 10,801 (2,411 ) 237,544 237,544 Other 54,073 299 (63 ) 54,309 54,309 Total corporate 3,967,795 121,650 (20,918 ) 4,068,527 4,068,527 Foreign 858,773 46,794 (2,762 ) 902,805 902,805 Total available for sale 12,869,809 326,916 (94,583 ) 13,102,142 13,102,142 Total investments in fixed maturity securities $ 12,958,335 $ 341,062 $ (94,583 ) $ 13,204,814 $ 13,190,668 ____________ (1) Gross unrealized gains and (losses) for residential mortgage-backed securities include $25,220 and $(818,691) as of June 30, 2017 and December 31, 2016 , respectively, related to securities with the non-credit portion of other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income. The amortized cost and fair value of fixed maturity securities at June 30, 2017 , by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations. (In thousands) Amortized Cost Fair Value Due in one year or less $ 803,520 $ 819,242 Due after one year through five years 5,237,765 5,368,120 Due after five years through ten years 3,169,976 3,311,894 Due after ten years 2,773,270 2,823,111 Mortgage-backed securities 1,202,992 1,208,239 Total $ 13,187,523 $ 13,530,606 At June 30, 2017 and December 31, 2016, there were no investments that exceeded 10% of common stockholders' equity, other than investments in United States government and government agency securities.

Investments in Equity Securitie

Investments in Equity Securities Available for Sale	6 Months Ended
	Jun. 30, 2017
Equity securities available for sale
Schedule of Available-for-sale Securities [Line Items]
Investments in Equity Securities Available for Sale	Investments in Equity Securities Available for Sale At June 30, 2017 and December 31, 2016 , investments in equity securities were as follows: (In thousands) Cost Gross Unrealized Fair Value Carrying Value Gains Losses June 30, 2017 Common stocks $ 87,185 $ 366,106 $ (5,691 ) $ 447,600 $ 447,600 Preferred stocks 119,083 47,208 (1,084 ) 165,207 165,207 Total $ 206,268 $ 413,314 $ (6,775 ) $ 612,807 $ 612,807 December 31, 2016 Common stocks $ 94,998 $ 351,906 $ (1,046 ) $ 445,858 $ 445,858 Preferred stocks 125,589 101,392 (3,639 ) 223,342 223,342 Total $ 220,587 $ 453,298 $ (4,685 ) $ 669,200 $ 669,200

Arbitrage Trading Account

Arbitrage Trading Account	6 Months Ended
	Jun. 30, 2017
Trading Securities [Abstract]
Arbitrage Trading Account	Arbitrage Trading Account At June 30, 2017 and December 31, 2016 , the fair and carrying values of the arbitrage trading account were $634 million and $300 million , respectively. The primary focus of the trading account is merger arbitrage. Merger arbitrage is the business of investing in the securities of publicly held companies which are the targets in announced tender offers and mergers. Arbitrage investing differs from other types of investing in its focus on transactions and events believed likely to bring about a change in value over a relatively short time period (usually four months or less). The Company uses put options, call options and swap contracts in order to mitigate the impact of potential changes in market conditions on the merger arbitrage trading account. These options and contracts are reported at fair value. As of June 30, 2017 , the fair value of long option contracts outstanding was $1 million (notional amount of $32 million ) and the fair value of short option contracts outstanding was $1 million (notional amount of $73 million ). Other than with respect to the use of these trading account securities, the Company does not make use of derivatives.

Net Investment Income

Net Investment Income	6 Months Ended
	Jun. 30, 2017
Net Investment Income [Abstract]
Net Investment Income	Net Investment Income Net investment income consists of the following: For the Three Months For the Six Months Ended June 30, Ended June 30, (In thousands) 2017 2016 2017 2016 Investment income earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 116,796 $ 108,342 $ 229,142 $ 217,177 Investment funds 8,895 18,456 35,544 35,092 Arbitrage trading account 5,457 3,252 11,817 6,442 Real estate 5,286 1,250 9,852 3,967 Equity securities available for sale 602 1,280 1,241 2,148 Gross investment income 137,036 132,580 287,596 264,826 Investment expense (1,772 ) (3,531 ) (3,473 ) (5,644 ) Net investment income $ 135,264 $ 129,049 $ 284,123 $ 259,182

Investment Funds

Investment Funds	6 Months Ended
	Jun. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Investment Funds	Investment Funds The Company evaluates whether it is an investor in a variable interest entity (VIE). Such entities do not have sufficient equity at risk to finance their activities without additional subordinated financial support, or the equity investors, as a group, do not have the characteristics of a controlling financial interest (primary beneficiary). The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE's capital structure, contractual terms, nature of the VIE's operations and purpose, and the Company's relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE and on an ongoing basis. The Company is not the primary beneficiary in any of its investment funds, and accordingly, carries its interests in investments funds under the equity method of accounting. The Company’s maximum exposure to loss with respect to these investments is limited to the carrying amount reported on the Company’s consolidated balance sheet and its unfunded commitments which were $354 million as of June 30, 2017. Investment funds consisted of the following: Carrying Value as of Income (Loss) from Investment Funds June 30, December 31, For the Six Months Ended June 30, (In thousands) 2017 2016 2017 2016 Real estate $ 611,598 $ 641,783 $ 19,518 $ 22,414 Energy 86,690 91,448 (8,639 ) 1,153 Hedge equity 72,685 73,913 (1,228 ) (2,030 ) Other funds 419,990 391,002 25,893 13,555 Total $ 1,190,963 $ 1,198,146 $ 35,544 $ 35,092 The Company's share of the earnings or losses of investment funds is generally reported on a one-quarter lag in order to facilitate the timely completion of the Company's consolidated financial statements.

Real Estate

Real Estate	6 Months Ended
	Jun. 30, 2017
Real Estate [Abstract]
Real Estate	Real Estate Investment in real estate represents directly owned property held for investment, as follows: Carrying Value June 30, December 31, (In thousands) 2017 2016 Properties in operation $ 447,721 $ 457,237 Properties under development 869,368 727,744 Total $ 1,317,089 $ 1,184,981 In 2017, properties in operation included a long-term ground lease in Washington, D.C., a hotel in Memphis, Tennessee, an office complex in New York City and office buildings in West Palm Beach and Palm Beach, Florida. Properties in operation are net of accumulated depreciation and amortization of $18,600,000 and $14,996,000 as of June 30, 2017 and December 31, 2016, respectively. Related depreciation expense was $3,604,000 and $3,279,000 for the six months ended June 30, 2017 and 2016 respectively. Future minimum rental income expected on operating leases relating to properties in operation is $9,248,244 in 2017, $27,797,511 in 2018, $29,246,483 in 2019, $28,527,541 in 2020, $29,145,221 in 2021, $28,784,655 in 2022 and $466,275,306 thereafter. Properties under development include an office building in London and a mixed-use project in Washington, D.C.

Loans Receivable

Loans Receivable	6 Months Ended
	Jun. 30, 2017
Receivables [Abstract]
Loans Receivable	Loans Receivable Loans receivable are as follows: (In thousands) June 30, 2017 December 31, 2016 Amortized cost (net of valuation allowance): Real estate loans $ 82,938 $ 92,415 Commercial loans 13,126 14,383 Total $ 96,064 $ 106,798 Fair value: Real estate loans $ 82,938 $ 92,415 Commercial loans 14,628 15,884 Total $ 97,566 $ 108,299 Valuation allowance: Specific $ 1,200 $ 1,200 General 2,183 2,197 Total $ 3,383 $ 3,397 For the Three Months Ended June 30, 2017 2016 Increase in valuation allowance $ — $ 93 For the Six Months Ended June 30, 2017 2016 Increase (decrease) in valuation allowance $ (14 ) $ 661 Loans receivable in non-accrual status were $4.5 million and $5.4 million as of June 30, 2017 and December 31, 2016, respectively. The Company monitors the performance of its loans receivable and assesses the ability of the borrower to pay principal and interest based upon loan structure, underlying property values, cash flow and related financial and operating performance of the property and market conditions. Loans receivable with a potential for default are further assessed using discounted cash flow analysis and comparable cost and sales methodologies, if appropriate. The real estate loans are secured by commercial real estate primarily located in New York. These loans generally earn interest at floating LIBOR-based interest rates and have maturities (inclusive of extension options) through August 2025. The commercial loans are with small business owners who have secured the related financing with the assets of the business. Commercial loans primarily earn interest on a fixed basis and have varying maturities generally not exceeding 10 years. In evaluating the real estate loans, the Company considers their credit quality indicators, including loan to value ratios, which compare the outstanding loan amount to the estimated value of the property, the borrower’s financial condition and performance with respect to loan terms, the position in the capital structure, the overall leverage in the capital structure and other market conditions. Based on these considerations, none of the real estate loans were considered to be impaired at June 30, 2017, and accordingly, the Company determined that a specific valuation allowance was not required.

Realized And Unrealized Investm

Realized And Unrealized Investment Gains (Losses)	6 Months Ended
	Jun. 30, 2017
Realized and Unrealized Investment Gains (Losses) [Abstract]
Realized and Unrealized Investment Gains (Losses)	Realized and Unrealized Investment Gains (Losses) Realized and unrealized investment gains (losses) are as follows: For the Three Months Ended June 30, For the Six Months Ended June 30, (In thousands) 2017 2016 2017 2016 Realized investment gains (losses): Fixed maturity securities: Gains $ 7,427 $ 10,110 $ 13,032 $ 33,174 Losses — (1,480 ) (3,965 ) (4,420 ) Equity securities available for sale 32,139 4,471 74,846 4,596 Investment funds (112 ) (4,793 ) 1,155 (5,253 ) Real estate (364 ) (464 ) 2,936 4,560 Other 1,363 (1,529 ) 4,797 (885 ) Net realized gains on investments sales 40,453 6,315 92,801 31,772 Other-than-temporary impairments (1) — — — (18,114 ) Net investment gains 40,453 6,315 92,801 13,658 Income tax expense (14,159 ) (2,210 ) (32,480 ) (4,780 ) After-tax net realized investment gains $ 26,294 $ 4,105 $ 60,321 $ 8,878 Change in unrealized investment gains (losses) of available for sale securities: Fixed maturity securities $ 56,857 $ 122,893 $ 94,841 $ 215,321 Previously impaired fixed maturity securities 743 1,874 844 1,819 Equity securities available for sale 6,176 27,814 (42,686 ) 40,950 Investment funds 4,506 4,004 5,712 12,885 Total change in unrealized investment gains 68,282 156,585 58,711 270,975 Income tax expense (24,713 ) (51,552 ) (23,973 ) (89,087 ) Noncontrolling interests (5 ) (5 ) 14 9 After-tax change in unrealized investment gains of available for sale securities $ 43,564 $ 105,028 $ 34,752 $ 181,897 ______________________ (1) There were no other than temporary impairments (OTTI) for the three and six months ended June 30, 2017, or for the three months ended June 30, 2016. OTTI for the six months ended June 30, 2016 of $18.1 million were related to common stock.

Securities In An Unrealized Los

Securities In An Unrealized Loss Position	6 Months Ended
	Jun. 30, 2017
Investments [Abstract]
Securities in Unrealized Loss Position	Securities in an Unrealized Loss Position The following tables summarize all securities in an unrealized loss position at June 30, 2017 and December 31, 2016 by the length of time those securities have been continuously in an unrealized loss position: Less Than 12 Months 12 Months or Greater Total (In thousands) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses June 30, 2017 U.S. government and government agency $ 115,584 $ 935 $ 30,925 $ 1,200 $ 146,509 $ 2,135 State and municipal 860,362 10,961 112,597 1,468 972,959 12,429 Mortgage-backed securities 585,106 6,827 128,391 4,038 713,497 10,865 Asset-backed securities 1,424,602 6,921 75,179 3,692 1,499,781 10,613 Corporate 612,215 4,599 41,688 3,641 653,903 8,240 Foreign government 115,875 742 1,973 30 117,848 772 Fixed maturity securities 3,713,744 30,985 390,753 14,069 4,104,497 45,054 Common stocks 24,004 4,953 9,040 738 33,044 5,691 Preferred stocks — — 24,589 1,084 24,589 1,084 Equity securities available for sale 24,004 4,953 33,629 1,822 57,633 6,775 Total $ 3,737,748 $ 35,938 $ 424,382 $ 15,891 $ 4,162,130 $ 51,829 December 31, 2016 U.S. government and government agency $ 112,709 $ 1,252 $ 35,450 $ 1,341 $ 148,159 $ 2,593 State and municipal 1,562,614 35,553 133,034 4,885 1,695,648 40,438 Mortgage-backed securities 625,903 11,103 109,066 4,828 734,969 15,931 Asset-backed securities 1,010,836 5,340 201,693 6,601 1,212,529 11,941 Corporate 1,035,245 13,448 65,147 7,470 1,100,392 20,918 Foreign government 213,246 1,985 24,820 777 238,066 2,762 Fixed maturity securities 4,560,553 68,681 569,210 25,902 5,129,763 94,583 Common stocks 336 22 8,755 1,024 9,091 1,046 Preferred stocks — — 22,034 3,639 22,034 3,639 Equity securities available for sale 336 22 30,789 4,663 31,125 4,685 Total $ 4,560,889 $ 68,703 $ 599,999 $ 30,565 $ 5,160,888 $ 99,268 Fixed Maturity Securities – A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at June 30, 2017 is presented in the table below: ($ in thousands) Number of Securities Aggregate Fair Value Gross Unrealized Loss Foreign government 3 $ 9,655 $ 250 Mortgage-backed securities 6 6,239 215 Asset-backed securities 4 3,299 137 Corporate 2 2,922 232 Total 15 $ 22,115 $ 834 For OTTI of fixed maturity securities that management does not intend to sell or, to be required to sell, the portion of the decline in value that is considered to be due to credit factors is recognized in earnings, and the portion of the decline in value that is considered to be due to non-credit factors is recognized in other comprehensive income. The Company has evaluated its fixed maturity securities in an unrealized loss position and believes the unrealized losses are due primarily to temporary market and sector-related factors rather than to issuer-specific factors. None of these securities are delinquent or in default under financial covenants. Based on its assessment of these issuers, the Company expects them to continue to meet their contractual payment obligations as they become due and does not consider any of these securities to be OTTI. Preferred Stocks – At June 30, 2017 , there was one preferred stock in an unrealized loss position, with a fair value of $24.6 million and a gross unrealized loss of $1.1 million . Based upon management’s view of the underlying value of the security, the Company does not consider the equity security to be OTTI. For six months ended June 30, 2017 and 2016, there was no OTTI for preferred stocks. Common Stocks – At June 30, 2017 , there were five common stocks in an unrealized loss position, with an aggregate fair value of $33.0 million and a gross unrealized loss of $5.7 million . Based on management's view of the underlying securities, the Company does not consider these equity securities to be OTTI. There was no OTTI of common stocks for the six months ended June 30, 2017. For the six months ended June 30, 2016, OTTI for common stocks was $ 18.1 million .

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company’s fixed maturity and equity securities classified as available for sale and its trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable. Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available. Substantially, all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation. If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information. For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate. The following tables present the assets and liabilities measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016 by level: (In thousands) Total Level 1 Level 2 Level 3 June 30, 2017 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 443,951 $ — $ 443,951 $ — State and municipal 4,442,811 — 4,442,811 — Mortgage-backed securities 1,191,907 — 1,191,907 — Asset-backed securities 2,192,030 — 2,191,857 173 Corporate 4,271,402 — 4,271,402 — Foreign government 892,299 — 892,299 — Total fixed maturity securities available for sale 13,434,400 — 13,434,227 173 Equity securities available for sale: Common stocks 447,600 438,560 — 9,040 Preferred stocks 165,207 — 161,545 3,662 Total equity securities available for sale 612,807 438,560 161,545 12,702 Arbitrage trading account 634,016 329,631 304,385 — Total $ 14,681,223 $ 768,191 $ 13,900,157 $ 12,875 Liabilities: Trading account securities sold but not yet purchased $ 62,860 $ 62,855 $ 5 $ — December 31, 2016 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 513,802 $ — $ 513,802 $ — State and municipal 4,519,503 — 4,519,503 — Mortgage-backed securities 1,189,645 — 1,189,645 — Asset-backed securities 1,907,860 — 1,907,677 183 Corporate 4,068,527 — 4,068,527 — Foreign government 902,805 — 902,805 — Total fixed maturity securities available for sale 13,102,142 — 13,101,959 183 Equity securities available for sale: Common stocks 445,858 429,647 7,457 8,754 Preferred stocks 223,342 — 219,680 3,662 Total equity securities available for sale 669,200 429,647 227,137 12,416 Arbitrage trading account 299,999 224,623 75,376 — Total $ 14,071,341 $ 654,270 $ 13,404,472 $ 12,599 Liabilities: Trading account securities sold but not yet purchased $ 51,179 $ 51,089 $ 90 $ — There were no significant transfers between Levels 1 and 2 during the six months ended June 30, 2017 or during the year ended December 31, 2016 . The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2017 and for the year ended December 31, 2016 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers Ending Balance In / (Out) Six Months Ended June 30, 2017: Assets: Fixed maturities securities available for sale: Asset-backed securities $ 183 $ 2 $ 16 $ — $ — $ (28 ) $ — $ — $ 173 Corporate — — — — — — — — — Total 183 2 16 — — (28 ) — — 173 Equity securities available for sale: Common stocks 8,754 — 286 — — — — — 9,040 Preferred stocks 3,662 — — — — — — — 3,662 Total 12,416 — 286 — — — — — 12,702 Arbitrage trading account — (78 ) 78 — — — — — — Total $ 12,599 $ (76 ) $ 380 $ — $ — $ (28 ) $ — $ — $ 12,875 Year ended December 31, 2016: Assets: Fixed maturities securities available for sale: Asset-backed securities $ 199 $ 3 $ 16 $ — $ — $ — $ (35 ) $ — $ 183 Corporate 154 177 — — — (331 ) — — — Total 353 180 16 — — (331 ) (35 ) — 183 Equity securities available for sale: Common stocks 7,829 — 160 — 765 — — — 8,754 Preferred stocks 3,624 38 — — — — — — 3,662 Total 11,453 38 160 — 765 — — — 12,416 Arbitrage trading account 176 (176 ) — — — — — — — Total $ 11,982 $ 42 $ 176 $ — $ 765 $ (331 ) $ (35 ) $ — $ 12,599 During the six months ended June 30, 2017 and for the year ended December 31, 2016, there were no t ransfers out of Level 3. Fair Value of Financial Instruments The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: June 30, 2017 December 31, 2016 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,514,085 $ 13,530,606 $ 13,190,668 $ 13,204,814 Equity securities available for sale 612,807 612,807 669,200 669,200 Arbitrage trading account 634,016 634,016 299,999 299,999 Loans receivable 96,064 97,566 106,798 108,299 Cash and cash equivalents 788,354 788,354 795,285 795,285 Trading account receivables from brokers and clearing organizations 164,696 164,696 484,593 484,593 Liabilities: Due to broker 124,428 124,428 19,416 19,416 Trading account securities sold but not yet purchased 62,860 62,860 51,179 51,179 Subordinated debentures 727,924 786,857 727,630 687,504 Senior notes and other debt 1,759,115 1,952,275 1,760,595 1,914,727 The estimated fair values of the Company’s fixed maturity securities, equity securities available for sale and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 16 above. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

Reserves for Loss and Loss Expe

Reserves for Loss and Loss Expenses	6 Months Ended
	Jun. 30, 2017
Insurance [Abstract]
Reserves for Loss and Loss Expenses	Reserves for Loss and Loss Expenses The Company's reserves for losses and loss expenses are comprised of case reserves and incurred but not reported liabilities (IBNR). When a claim is reported, a case reserve is established for the estimated ultimate payment based upon known information about the claim. As more information about the claim becomes available over time, case reserves are adjusted up or down as appropriate. Reserves are also established on an aggregate basis to provide for IBNR liabilities and expected loss reserve development on reported claims. Loss reserves included in the Company’s financial statements represent management’s best estimates based upon an actuarially derived point estimate and other considerations. The Company uses a variety of actuarial techniques and methods to derive an actuarial point estimate for each operating unit. These methods include paid loss development, incurred loss development, paid and incurred Bornhuetter-Ferguson methods and frequency and severity methods. In circumstances where one actuarial method is considered more credible than the others, that method is used to set the point estimate. The actuarial point estimate may also be based on a judgmental weighting of estimates produced from each of the methods considered. Industry loss experience is used to supplement the Company’s own data in selecting “tail factors” in areas where the Company’s own data is limited. The actuarial data is analyzed by line of business, coverage and accident or policy year, as appropriate, for each operating unit. The establishment of the actuarially derived loss reserve point estimate also includes consideration of qualitative factors that may affect the ultimate losses. These qualitative considerations include, among others, the impact of re-underwriting initiatives, changes in the mix of business, changes in distribution sources and changes in policy terms and conditions. The key assumptions used to arrive at the best estimate of loss reserves are the expected loss ratios, rate of loss cost inflation, and reported and paid loss emergence patterns. Expected loss ratios represent management’s expectation of losses at the time the business is priced and written, before any actual claims experience has emerged. This expectation is a significant determinant of the estimate of loss reserves for recently written business where there is little paid or incurred loss data to consider. Expected loss ratios are generally derived from historical loss ratios adjusted for the impact of rate changes, loss cost trends and known changes in the type of risks underwritten. Expected loss ratios are estimated for each key line of business within each operating unit. Expected loss cost inflation is particularly important for the long-tail lines, such as excess casualty, and claims with a high medical component, such as workers’ compensation. Reported and paid loss emergence patterns are used to project current reported or paid loss amounts to their ultimate settlement value. Loss development factors are based on the historical emergence patterns of paid and incurred losses, and are derived from the Company’s own experience and industry data. The paid loss emergence pattern is also significant to excess and assumed workers’ compensation reserves because those reserves are discounted to their estimated present value based upon such estimated payout patterns. Loss frequency and severity are measures of loss activity that are considered in determining the key assumptions described in our discussion of loss and loss expense reserves, including expected loss ratios, rate of loss cost inflation and reported and paid loss emergence patterns. Loss frequency is a measure of the number of claims per unit of insured exposure, and loss severity is a measure of the average size of claims. Factors affecting loss frequency include the effectiveness of loss controls and safety programs and changes in economic activity or weather patterns. Factors affecting loss severity include changes in policy limits, retentions, rate of inflation and judicial interpretations. Another factor affecting estimates of loss frequency and severity is the loss reporting lag, which is the period of time between the occurrence of a loss and the date the loss is reported to the Company. The length of the loss reporting lag affects our ability to accurately predict loss frequency (loss frequencies are more predictable for lines with short reporting lags) as well as the amount of reserves needed for incurred but not reported losses (less IBNR is required for lines with short reporting lags). As a result, loss reserves for lines with short reporting lags are likely to have less variation from initial loss estimates. For lines with short reporting lags, which include commercial automobile, primary workers’ compensation, other liability (claims-made) and property business, the key assumption is the loss emergence pattern used to project ultimate loss estimates from known losses paid or reported to date. For lines of business with long reporting lags, which include other liability (occurrence), products liability, excess workers’ compensation and liability reinsurance, the key assumption is the expected loss ratio since there is often little paid or incurred loss data to consider. Historically, the Company has experienced less variation from its initial loss estimates for lines of businesses with short reporting lags than for lines of business with long reporting lags. The key assumptions used in calculating the most recent estimate of the loss reserves are reviewed each quarter and adjusted, to the extent necessary, to reflect the latest reported loss data, current trends and other factors observed. The table below provides a reconciliation of the beginning and ending reserve balances: June 30, (In thousands) 2017 2016 Net reserves at beginning of year $ 9,590,265 $ 9,244,872 Net provision for losses and loss expenses: Claims occurring during the current year (1) 1,926,394 1,878,458 Decrease in estimates for claims occurring in prior years (2) (3) (6,458 ) (15,511 ) Loss reserve discount accretion 24,366 23,536 Total 1,944,302 1,886,483 Net payments for claims: Current year 315,437 480,601 Prior year 1,432,828 1,188,704 Total 1,748,265 1,669,305 Foreign currency translation 37,097 (19,768 ) Net reserves at end of period 9,823,399 9,442,282 Ceded reserve at end of period 1,500,868 1,455,594 Gross reserves at end of period $ 11,324,267 $ 10,897,876 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $ 11,349,000 and $ 9,402,000 in 2017 and 2016, respectively. (2) The decrease in estimates for claims occurring in prior years is net of loss reserve discount. On an undiscounted basis, the estimates for claims occurring in prior years decreased by $ 14,873,000 and $ 21,696,000 in 2017 and 2016, respectively. (3) For certain retrospectively rated insurance policies and reinsurance agreements, reserve development is offset by additional or return premiums. Favorable development, net of additional and return premiums, was $24 million and $29 million as of June 30, 2017 and 2016, respectively. In 2017, favorable prior year development (net of additional and return premiums) of $23.6 million included $49.4 million of favorable development for the Insurance segment, partially offset by $25.8 million of adverse development for the Reinsurance segment. The favorable development for the Insurance segment was primarily attributable to workers' compensation business (including excess workers' compensation) and excess & surplus lines casualty business. The favorable workers' compensation development was spread across many accident years, including prior to 2008, but was most significant in accident years 2014 and 2015. The favorable workers' compensation development reflects a continuation of the benign loss cost trends experienced during 2016, particularly the favorable claim frequency trends (i.e., number of reported claims per unit of exposure). The favorable development for excess & surplus lines casualty business resulted from loss cost trends emerging more favorably than our initial expectations, primarily in accident years 2014 through 2016. The adverse development for the Reinsurance segment was almost entirely due to reserve strengthening during the first quarter associated with claims impacted by the change in the Ogden discount rate in the UK. The Ogden rate is the discount rate used to calculate lump-sum bodily injury payouts in the UK, and was reduced by the UK Ministry of Justice from +2.5% to -0.75%. The adverse development mostly related to UK motor bodily injury claims which we reinsured on an excess of loss basis in accident years 2012 through 2016. In 2016, favorable prior year development (net of additional and return premiums) of $ 28.7 million included $ 24.8 million for the Insurance segment and $ 3.9 million for the Reinsurance segment. The favorable development for the Insurance segment was primarily attributable to workers' compensation business, partially offset by adverse development for commercial auto liability and professional liability. The favorable development for workers' compensation stems from accident years 2003 through 2015, but is concentrated in accident years 2014 and 2015; it reflects favorable claims frequency trends (i.e., number of reported claims per unit of exposure) which continued to be better than we had expected. The unfavorable development for commercial auto liability was driven by higher large loss activity than expected in accident years 2014 and 2015, while the unfavorable development for medical professional liability was primarily in accident years 2011 through 2013 and stemmed from a particular class of medical professional liability that we discontinued writing in 2013.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Of Financial Instruments	Fair Value Measurements The Company’s fixed maturity and equity securities classified as available for sale and its trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable. Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available. Substantially, all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation. If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information. For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate. The following tables present the assets and liabilities measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016 by level: (In thousands) Total Level 1 Level 2 Level 3 June 30, 2017 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 443,951 $ — $ 443,951 $ — State and municipal 4,442,811 — 4,442,811 — Mortgage-backed securities 1,191,907 — 1,191,907 — Asset-backed securities 2,192,030 — 2,191,857 173 Corporate 4,271,402 — 4,271,402 — Foreign government 892,299 — 892,299 — Total fixed maturity securities available for sale 13,434,400 — 13,434,227 173 Equity securities available for sale: Common stocks 447,600 438,560 — 9,040 Preferred stocks 165,207 — 161,545 3,662 Total equity securities available for sale 612,807 438,560 161,545 12,702 Arbitrage trading account 634,016 329,631 304,385 — Total $ 14,681,223 $ 768,191 $ 13,900,157 $ 12,875 Liabilities: Trading account securities sold but not yet purchased $ 62,860 $ 62,855 $ 5 $ — December 31, 2016 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 513,802 $ — $ 513,802 $ — State and municipal 4,519,503 — 4,519,503 — Mortgage-backed securities 1,189,645 — 1,189,645 — Asset-backed securities 1,907,860 — 1,907,677 183 Corporate 4,068,527 — 4,068,527 — Foreign government 902,805 — 902,805 — Total fixed maturity securities available for sale 13,102,142 — 13,101,959 183 Equity securities available for sale: Common stocks 445,858 429,647 7,457 8,754 Preferred stocks 223,342 — 219,680 3,662 Total equity securities available for sale 669,200 429,647 227,137 12,416 Arbitrage trading account 299,999 224,623 75,376 — Total $ 14,071,341 $ 654,270 $ 13,404,472 $ 12,599 Liabilities: Trading account securities sold but not yet purchased $ 51,179 $ 51,089 $ 90 $ — There were no significant transfers between Levels 1 and 2 during the six months ended June 30, 2017 or during the year ended December 31, 2016 . The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2017 and for the year ended December 31, 2016 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers Ending Balance In / (Out) Six Months Ended June 30, 2017: Assets: Fixed maturities securities available for sale: Asset-backed securities $ 183 $ 2 $ 16 $ — $ — $ (28 ) $ — $ — $ 173 Corporate — — — — — — — — — Total 183 2 16 — — (28 ) — — 173 Equity securities available for sale: Common stocks 8,754 — 286 — — — — — 9,040 Preferred stocks 3,662 — — — — — — — 3,662 Total 12,416 — 286 — — — — — 12,702 Arbitrage trading account — (78 ) 78 — — — — — — Total $ 12,599 $ (76 ) $ 380 $ — $ — $ (28 ) $ — $ — $ 12,875 Year ended December 31, 2016: Assets: Fixed maturities securities available for sale: Asset-backed securities $ 199 $ 3 $ 16 $ — $ — $ — $ (35 ) $ — $ 183 Corporate 154 177 — — — (331 ) — — — Total 353 180 16 — — (331 ) (35 ) — 183 Equity securities available for sale: Common stocks 7,829 — 160 — 765 — — — 8,754 Preferred stocks 3,624 38 — — — — — — 3,662 Total 11,453 38 160 — 765 — — — 12,416 Arbitrage trading account 176 (176 ) — — — — — — — Total $ 11,982 $ 42 $ 176 $ — $ 765 $ (331 ) $ (35 ) $ — $ 12,599 During the six months ended June 30, 2017 and for the year ended December 31, 2016, there were no t ransfers out of Level 3. Fair Value of Financial Instruments The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: June 30, 2017 December 31, 2016 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,514,085 $ 13,530,606 $ 13,190,668 $ 13,204,814 Equity securities available for sale 612,807 612,807 669,200 669,200 Arbitrage trading account 634,016 634,016 299,999 299,999 Loans receivable 96,064 97,566 106,798 108,299 Cash and cash equivalents 788,354 788,354 795,285 795,285 Trading account receivables from brokers and clearing organizations 164,696 164,696 484,593 484,593 Liabilities: Due to broker 124,428 124,428 19,416 19,416 Trading account securities sold but not yet purchased 62,860 62,860 51,179 51,179 Subordinated debentures 727,924 786,857 727,630 687,504 Senior notes and other debt 1,759,115 1,952,275 1,760,595 1,914,727 The estimated fair values of the Company’s fixed maturity securities, equity securities available for sale and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 16 above. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

Reinsurance

Reinsurance	6 Months Ended
	Jun. 30, 2017
Insurance [Abstract]
Reinsurance	Reinsurance The following is a summary of reinsurance financial information: For the Three Months For the Six Months Ended June 30, Ended June 30, (In thousands) 2017 2016 2017 2016 Written premiums: Direct $ 1,727,014 $ 1,708,535 $ 3,448,076 $ 3,417,664 Assumed 160,139 230,830 375,283 477,398 Ceded (322,902 ) (296,796 ) (612,270 ) (588,771 ) Total net premiums written $ 1,564,251 $ 1,642,569 $ 3,211,089 $ 3,306,291 Earned premiums: Direct $ 1,666,938 $ 1,609,644 $ 3,280,302 $ 3,177,712 Assumed 193,683 225,643 402,310 444,009 Ceded (291,918 ) (275,494 ) (543,868 ) (534,593 ) Total net premiums earned $ 1,568,703 $ 1,559,793 $ 3,138,744 $ 3,087,128 Ceded losses and loss expenses incurred $ 142,609 $ 167,265 $ 177,801 $ 294,194 Ceded commissions earned $ 57,752 $ 50,172 $ 114,302 $ 96,494 The Company reinsures a portion of its insurance exposures in order to reduce its net liability on individual risks and catastrophe losses. The Company also cedes premiums to state assigned risk plans and captive insurance companies. Estimated amounts due from reinsurers are reported net of reserves for uncollectible reinsurance of $1 million as of June 30, 2017 and December 31, 2016 .

Restricted Stock Units

Restricted Stock Units	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Restricted Stock Units	Restricted Stock Units Pursuant to its stock incentive plan, the Company may issue restricted stock units (RSUs) to employees of the Company and its subsidiaries. The RSUs generally vest three to five years from the award date and are subject to other vesting and forfeiture provisions contained in the award agreement. RSUs are expensed pro-ratably over the vesting period. RSU expenses were $21 million and $16 million for the six months ended June 30, 2017 and 2016 , respectively. A summary of RSUs issued in the six months ended June 30, 2017 and 2016 follows: ($ in thousands) Units Fair Value 2017 6,020 $ 405 2016 17,654 $ 964

Litigation and Contingent Liabi

Litigation and Contingent Liabilities	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Litigation and Contingent Liabilities	Litigation and Contingent Liabilities In the ordinary course of business, the Company is subject to disputes, litigation and arbitration arising from its insurance and reinsurance businesses. These matters are generally related to insurance and reinsurance claims and are considered in the establishment of loss and loss expense reserves. In addition, the Company may also become involved in legal actions which seek extra-contractual damages, punitive damages or penalties, including claims alleging bad faith in handling of insurance claims. The Company expects its ultimate liability with respect to such matters will not be material to its financial condition. However, adverse outcomes on such matters are possible, from time to time, and could be material to the Company’s results of operations in any particular financial reporting period.

Business Segments

Business Segments	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Business Segments	Business Segments The Company’s reportable segments include the following two business segments, plus a corporate segment: • Insurance - primarily commercial insurance business, including excess and surplus lines and admitted lines in the United States, United Kingdom, Continental Europe, South America, Canada, Mexico, Scandinavia, Asia and Australia; and • Reinsurance - reinsurance business on a facultative and treaty basis, primarily in the United States, United Kingdom, Continental Europe, Australia, the Asia-Pacific Region and South Africa. Commencing with the first quarter of 2017, the Company reclassified two businesses from the Insurance Segment to the Reinsurance segment. Reclassifications have been made to the Company's 2016 financial information to conform with this presentation. The accounting policies of the segments are the same as those described in the summary of significant accounting policies. Income tax expense and benefits are calculated based upon the Company's overall effective tax rate. Summary financial information about the Company's reporting segments is presented in the following tables. Income (loss) before income taxes by segment includes allocated investment income. Identifiable assets by segment are those assets used in or allocated to the operation of each segment. Revenues (In thousands) Earned Premiums Investment Income Other Total (1) Pre-Tax Income (Loss) Net Income (Loss) to Common Stockholders Three months ended June 30, 2017 Insurance $ 1,415,586 $ 102,719 $ 22,984 $ 1,541,289 $ 186,134 $ 124,442 Reinsurance 153,117 21,491 — 174,608 14,771 10,324 Corporate, other and eliminations (2) — 11,054 80,645 91,699 (80,397 ) (52,056 ) Net investment gains — — 40,453 40,453 40,453 26,294 Total $ 1,568,703 $ 135,264 $ 144,082 $ 1,848,049 $ 160,961 $ 109,004 Three months ended June 30, 2016 Insurance $ 1,390,744 $ 94,155 $ 27,603 $ 1,512,502 $ 176,500 $ 119,135 Reinsurance 169,049 25,372 — 194,421 23,834 16,681 Corporate, other and eliminations (2) — 9,522 133,154 142,676 (48,335 ) (30,954 ) Net investment gains — — 6,315 6,315 6,315 4,105 Total $ 1,559,793 $ 129,049 $ 167,072 $ 1,855,914 $ 158,314 $ 108,967 Six months ended June 30, 2017: Insurance $ 2,828,755 214,628 $ 41,271 $ 3,084,654 $ 386,127 $ 257,458 Reinsurance 309,989 46,269 — 356,258 19,364 13,983 Corporate, other and eliminations (2) — 23,226 161,528 184,754 (153,034 ) (99,311 ) Net investment gains — — 92,801 92,801 92,801 60,321 Total $ 3,138,744 $ 284,123 $ 295,600 $ 3,718,467 $ 345,258 $ 232,451 Six months ended June 30, 2016: Insurance $ 2,757,350 $ 193,605 $ 54,396 $ 3,005,351 $ 376,153 $ 253,639 Reinsurance 329,778 49,552 — 379,330 51,893 36,070 Corporate, other and eliminations (2) — 16,025 248,761 264,786 (108,714 ) (70,110 ) Net investment gains — — 13,658 13,658 13,658 8,878 Total $ 3,087,128 $ 259,182 $ 316,815 $ 3,663,125 $ 332,990 $ 228,477 _________________ (1) Revenues for Insurance from foreign countries for the three months ended June 30, 2017 and 2016 were $168 million and $179 million and for the six months ended June 30, 2017 and 2016 were $347 million and $359 million , respectively. Revenues for Reinsurance from foreign countries for the three months ended June 30, 2017 and 2016 were both $50 million and for the six months ended June 30, 2017 and 2016 were $101 million and $105 million , respectively. (2) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments. Identifiable Assets (In thousands) June 30, 2017 December 31, 2016 Insurance $ 18,687,170 $ 19,137,758 Reinsurance 3,085,961 2,524,338 Corporate, other and eliminations 2,220,360 1,687,980 Consolidated $ 23,993,491 $ 23,350,076 Net premiums earned by major line of business are as follows: For the Three Months For the Six Months Ended June 30, Ended June 30, (In thousands) 2017 2016 2017 2016 Insurance: Other liability $ 460,059 $ 433,472 $ 911,889 $ 847,000 Workers’ compensation 366,950 344,736 728,086 688,317 Short-tail lines (1) 290,696 322,493 599,930 649,570 Commercial automobile 161,526 159,892 319,653 316,709 Professional liability 136,355 130,151 269,197 255,754 Total Insurance 1,415,586 1,390,744 2,828,755 2,757,350 Reinsurance: Casualty 93,212 100,113 187,952 204,418 Property 59,905 68,936 122,037 125,360 Total Reinsurance 153,117 169,049 309,989 329,778 Total $ 1,568,703 $ 1,559,793 $ 3,138,744 $ 3,087,128 ______________ (1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

Subsequent Event

Subsequent Event	6 Months Ended
	Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event In July 2017, the Company sold a real estate investment, an office building in Washington, D.C., for which the Company expects to realize a pre-tax gain of approximately $120 million in the third quarter of 2017.

Recent Accounting Pronounceme31

Recent Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Per Share Data	Per Share Data The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 4,087,731 common shares held in a grantor trust established in March 2017). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units (RSUs). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently adopted accounting pronouncements: In May 2015, the FASB issued ASU 2015-09, Disclosures about Short-Duration Contracts. ASU 2015-09 requires companies that issue short duration insurance contracts to disclose additional information, including: (i) incurred and paid claims development tables; (ii) frequency and severity of claims; and (iii) information about material changes in judgments made in calculating the liability for unpaid claim adjustment expenses, including reasons for the change and the effects on the financial statements. The Company adopted this updated guidance on January 1, 2016 with regard to the annual requirements and on January 1, 2017 with regard to the interim requirements. The amendments in ASU 2015-09 are applied retrospectively by providing comparative disclosures for each period presented, except for those requirements that apply only to the current period. As the requirements are disclosure only, the adoption of this guidance did not impact our financial condition or results of operations, but did result in additional disclosures. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 includes provisions intended to simplify various previous provisions related to how share-based payments are accounted for and presented in the financial statements. Under the new guidance, excess tax benefits (deductions for share based payment awards for tax purposes that exceed the compensation cost recognized for financial reporting purposes) are reported within the income tax expense financial statement line item. Previously, excess tax benefits were reported within additional paid in capital. The Company adopted this updated guidance on January 1, 2017 prospectively. The adoption of this guidance did not have a material impact on the Company's financial condition or results of operations. All other accounting and reporting standards that became effective in 2017 were either not applicable to the Company or their adoption did not have a material impact on the Company. Accounting and reporting standards that are not yet effective: In May 2014, the FASB issued ASU 2014-09, Revenue from Customers. ASU 2014-09 clarifies the principles for recognizing revenue. While insurance contracts are not within the scope of this updated guidance, the Company’s insurance service fee revenue and non-insurance business revenue will be subject to this updated guidance. The updated guidance requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. The updated guidance, as amended by ASU 2015-14, is effective for public business entities for annual and interim reporting periods beginning after December 15, 2017. The adoption of this guidance is not expected to have a material effect on the Company’s financial condition or results of operations. In January 2016, the FASB issued ASU 2016-01, Financial Instruments. ASU 2016-01 amends the accounting guidance for financial instruments to require all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The updated guidance is effective for public business entities for annual reporting periods beginning after December 15, 2017 and interim periods within those years. The adoption of this guidance is not expected to have a material effect on the Company’s financial condition upon adoption, but will impact results of operations after adoption of this guidance as unrealized gains and losses on equity securities will no longer be reported directly in accumulated other comprehensive income (AOCI), but will instead be reported in net income. In February 2016, the FASB issued ASU 2016-02, Leases, which amends the accounting and disclosure guidance for leases. This guidance retains the two classifications of a lease, as either an operating or finance lease, both of which will require lessees to recognize a right-of-use asset and a lease liability for leases with terms of more than 12 months. The right-of-use asset and the lease liability will be determined based upon the present value of cash flows. Finance leases will reflect the financial arrangement by recognizing interest expense on the lease liability separately from the amortization expense of the right-of-use asset. Operating leases will recognize lease expense (with no separate recognition of interest expense) on a straight-line basis over the term of the lease. The accounting by lessors is not significantly changed by the updated guidance. The updated guidance is effective for reporting periods beginning after December 15, 2018, and will require that the earliest comparative period presented include the measurement and recognition of existing leases with an adjustment to equity as if the updated guidance had always been applied. The Company is currently evaluating the impact that the adoption of this guidance will have on its results of operations, financial position and liquidity. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses, which amends the accounting guidance for credit losses on financial instruments. The updated guidance amends the current other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. This guidance also applies a new current expected credit loss model for determining credit-related impairments for financial instruments measured at amortized cost. The updated guidance is effective for reporting periods beginning after December 15, 2019. The Company will not be able to determine the impact the adoption of this guidance will have on its results of operations, financial position or liquidity until the year the guidance becomes effective. All other recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.

Per Share Data (Tables)

Per Share Data (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Weighted average number of common shares	The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows: For the Three Months For the Six Months Ended June 30, Ended June 30, (In thousands) 2017 2016 2017 2016 Basic 125,334 122,616 123,623 122,698 Diluted 128,601 128,575 128,546 128,562

Acquisitions_Dispositions (Tabl

Acquisitions/Dispositions (Tables)	6 Months Ended
	Jun. 30, 2017
Business Combinations [Abstract]
Summary of fair value of net assets acquired and liabilities assumed	The following table summarizes the initial estimated fair value of net assets acquired and liabilities assumed for the business combination completed in 2017: (In thousands) 2017 Cash and cash equivalents $ 1,154 Real estate, furniture and equipment 6,434 Goodwill and other intangibles assets 62,406 Other assets 9,417 Total assets acquired 79,411 Other liabilities assumed (1,911 ) Noncontrolling interest (5,000 ) Net assets acquired $ 72,500

Consolidated Statements of Co34

Consolidated Statements of Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Components of changes in accumulated other comprehensive income (loss)	The following table presents the components of the changes in accumulated other comprehensive income ("AOCI"): (In thousands) Unrealized Investment Gains (Losses) Currency Translation Adjustments Accumulated Other Comprehensive Income As of and for the six months ended June 30, 2017: Changes in AOCI Beginning of period $ 427,154 $ (371,586 ) $ 55,568 Other comprehensive income before reclassifications 89,309 42,982 132,291 Amounts reclassified from AOCI (54,543 ) — (54,543 ) Other comprehensive income 34,766 42,982 77,748 Unrealized investment gain related to non-controlling interest (14 ) — (14 ) End of period $ 461,906 $ (328,604 ) $ 133,302 Amounts reclassified from AOCI Pre-tax $ (83,912 ) (1) $ — $ (83,912 ) Tax effect 29,369 (2) — 29,369 After-tax amounts reclassified $ (54,543 ) $ — $ (54,543 ) Other comprehensive income Pre-tax $ 58,711 $ 42,982 $ 101,693 Tax effect (23,945 ) — (23,945 ) Other comprehensive income $ 34,766 $ 42,982 $ 77,748 As of and for the three months ended June 30, 2017: Changes in AOCI Beginning of period $ 418,342 $ (348,851 ) $ 69,491 Other comprehensive income before reclassifications 69,315 20,247 89,562 Amounts reclassified from AOCI (25,718 ) — (25,718 ) Other comprehensive income 43,597 20,247 63,844 Unrealized investment gain related to non-controlling interest (33 ) — (33 ) End of period $ 461,906 $ (328,604 ) $ 133,302 Amounts reclassified from AOCI Pre-tax $ (39,566 ) (1) $ — $ (39,566 ) Tax effect 13,848 (2) — 13,848 After-tax amounts reclassified $ (25,718 ) $ — $ (25,718 ) Other comprehensive income Pre-tax $ 68,282 $ 20,247 $ 88,529 Tax effect (24,685 ) — (24,685 ) Other comprehensive income $ 43,597 $ 20,247 $ 63,844 _________________________ (1) Net investment gains in the consolidated statements of income. (2) Income tax expense in the consolidated statements of income. (In thousands) Unrealized Investment Gains (Losses) Currency Translation Adjustments Accumulated Other Comprehensive Income As of and for the six months ended June 30, 2016: Changes in AOCI Beginning of period $ 180,695 $ (247,393 ) $ (66,698 ) Other comprehensive income before reclassifications 191,791 (57,917 ) 133,874 Amounts reclassified from AOCI (9,903 ) — (9,903 ) Other comprehensive income 181,888 (57,917 ) 123,971 Unrealized investment losses related to non-controlling interest 9 — 9 End of period $ 362,592 $ (305,310 ) $ 57,282 Amounts reclassified from AOCI Pre-tax $ (15,235 ) (1) $ — $ (15,235 ) Tax effect 5,332 (2) — 5,332 After-tax amounts reclassified $ (9,903 ) $ — $ (9,903 ) Other comprehensive income Pre-tax $ 270,995 $ (57,917 ) $ 213,078 Tax effect (89,107 ) — (89,107 ) Other comprehensive income $ 181,888 $ (57,917 ) $ 123,971 As of and for the three months ended June 30, 2016: Changes in AOCI Beginning of period $ 257,564 $ (249,440 ) $ 8,124 Other comprehensive income before reclassifications 113,549 (55,870 ) 57,679 Amounts reclassified from AOCI (8,516 ) — (8,516 ) Other comprehensive income 105,033 (55,870 ) 49,163 Unrealized investment gain related to non-controlling interest (5 ) — (5 ) End of period $ 362,592 $ (305,310 ) $ 57,282 Amounts reclassified from AOCI Pre-tax $ (13,101 ) (1) $ — $ (13,101 ) Tax effect 4,585 (2) — 4,585 After-tax amounts reclassified $ (8,516 ) $ — $ (8,516 ) Other comprehensive income Pre-tax $ 156,605 $ (55,870 ) $ 100,735 Tax effect (51,572 ) — (51,572 ) Other comprehensive income $ 105,033 $ (55,870 ) $ 49,163 _______________ (1) Net investment gains in the consolidated statements of income. (2) Income tax expense in the consolidated statements of income.

Investments in Fixed Maturity35

Investments in Fixed Maturity Securities (Tables)	6 Months Ended
	Jun. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of investments in fixed maturity securities	At June 30, 2017 and December 31, 2016 , investments in fixed maturity securities were as follows: (In thousands) Amortized Cost Gross Unrealized Fair Value Carrying Value Gains Losses June 30, 2017 Held to maturity: State and municipal $ 64,931 $ 14,943 $ — $ 79,874 $ 64,931 Residential mortgage-backed 14,754 1,578 — 16,332 14,754 Total held to maturity 79,685 16,521 — 96,206 79,685 Available for sale: U.S. government and government agency 432,145 13,941 (2,135 ) 443,951 443,951 State and municipal: Special revenue 2,770,582 80,887 (9,471 ) 2,841,998 2,841,998 State general obligation 471,980 21,596 (1,359 ) 492,217 492,217 Pre-refunded 312,535 21,825 (216 ) 334,144 334,144 Corporate backed 384,609 10,609 (916 ) 394,302 394,302 Local general obligation 354,110 26,507 (467 ) 380,150 380,150 Total state and municipal 4,293,816 161,424 (12,429 ) 4,442,811 4,442,811 Mortgage-backed securities: Residential (1) 997,886 13,968 (9,608 ) 1,002,246 1,002,246 Commercial 190,352 566 (1,257 ) 189,661 189,661 Total mortgage-backed securities 1,188,238 14,534 (10,865 ) 1,191,907 1,191,907 Asset-backed 2,196,114 6,529 (10,613 ) 2,192,030 2,192,030 Corporate: Industrial 2,394,374 73,884 (2,717 ) 2,465,541 2,465,541 Financial 1,444,201 49,524 (4,929 ) 1,488,796 1,488,796 Utilities 255,777 12,725 (576 ) 267,926 267,926 Other 48,875 282 (18 ) 49,139 49,139 Total corporate 4,143,227 136,415 (8,240 ) 4,271,402 4,271,402 Foreign 854,298 38,773 (772 ) 892,299 892,299 Total available for sale 13,107,838 371,616 (45,054 ) 13,434,400 13,434,400 Total investments in fixed maturity securities $ 13,187,523 $ 388,137 $ (45,054 ) $ 13,530,606 $ 13,514,085 (In thousands) Amortized Gross Unrealized Fair Carrying Gains Losses December 31, 2016 Held to maturity: State and municipal $ 72,582 $ 12,453 $ — $ 85,035 $ 72,582 Residential mortgage-backed 15,944 1,693 — 17,637 15,944 Total held to maturity 88,526 14,146 — 102,672 88,526 Available for sale: U.S. government and government agency 496,187 20,208 (2,593 ) 513,802 513,802 State and municipal: Special revenue 2,791,211 58,559 (26,315 ) 2,823,455 2,823,455 State general obligation 524,682 16,964 (5,139 ) 536,507 536,507 Pre-refunded 356,535 19,181 (165 ) 375,551 375,551 Corporate backed 410,933 6,172 (6,452 ) 410,653 410,653 Local general obligation 360,022 15,682 (2,367 ) 373,337 373,337 Total state and municipal 4,443,383 116,558 (40,438 ) 4,519,503 4,519,503 Mortgage-backed securities: Residential (1) 1,034,301 15,431 (12,950 ) 1,036,782 1,036,782 Commercial 155,540 304 (2,981 ) 152,863 152,863 Total mortgage-backed securities 1,189,841 15,735 (15,931 ) 1,189,645 1,189,645 Asset-backed 1,913,830 5,971 (11,941 ) 1,907,860 1,907,860 Corporate: Industrial 2,315,567 71,007 (7,174 ) 2,379,400 2,379,400 Financial 1,369,001 39,543 (11,270 ) 1,397,274 1,397,274 Utilities 229,154 10,801 (2,411 ) 237,544 237,544 Other 54,073 299 (63 ) 54,309 54,309 Total corporate 3,967,795 121,650 (20,918 ) 4,068,527 4,068,527 Foreign 858,773 46,794 (2,762 ) 902,805 902,805 Total available for sale 12,869,809 326,916 (94,583 ) 13,102,142 13,102,142 Total investments in fixed maturity securities $ 12,958,335 $ 341,062 $ (94,583 ) $ 13,204,814 $ 13,190,668 ____________ (1) Gross unrealized gains and (losses) for residential mortgage-backed securities include $25,220 and $(818,691) as of June 30, 2017 and December 31, 2016 , respectively, related to securities with the non-credit portion of other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income.
Amortized cost and fair value of fixed maturity securities by contractual maturity	The amortized cost and fair value of fixed maturity securities at June 30, 2017 , by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations. (In thousands) Amortized Cost Fair Value Due in one year or less $ 803,520 $ 819,242 Due after one year through five years 5,237,765 5,368,120 Due after five years through ten years 3,169,976 3,311,894 Due after ten years 2,773,270 2,823,111 Mortgage-backed securities 1,202,992 1,208,239 Total $ 13,187,523 $ 13,530,606

Investments in Equity Securit36

Investments in Equity Securities Available for Sale (Tables)	6 Months Ended
	Jun. 30, 2017
Equity securities available for sale
Schedule of Available-for-sale Securities [Line Items]
Schedule of Investments in Equity Securities	At June 30, 2017 and December 31, 2016 , investments in equity securities were as follows: (In thousands) Cost Gross Unrealized Fair Value Carrying Value Gains Losses June 30, 2017 Common stocks $ 87,185 $ 366,106 $ (5,691 ) $ 447,600 $ 447,600 Preferred stocks 119,083 47,208 (1,084 ) 165,207 165,207 Total $ 206,268 $ 413,314 $ (6,775 ) $ 612,807 $ 612,807 December 31, 2016 Common stocks $ 94,998 $ 351,906 $ (1,046 ) $ 445,858 $ 445,858 Preferred stocks 125,589 101,392 (3,639 ) 223,342 223,342 Total $ 220,587 $ 453,298 $ (4,685 ) $ 669,200 $ 669,200

Net Investment Income (Tables)

Net Investment Income (Tables)	6 Months Ended
	Jun. 30, 2017
Net Investment Income [Abstract]
Schedule of Net Investment Income	Net investment income consists of the following: For the Three Months For the Six Months Ended June 30, Ended June 30, (In thousands) 2017 2016 2017 2016 Investment income earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 116,796 $ 108,342 $ 229,142 $ 217,177 Investment funds 8,895 18,456 35,544 35,092 Arbitrage trading account 5,457 3,252 11,817 6,442 Real estate 5,286 1,250 9,852 3,967 Equity securities available for sale 602 1,280 1,241 2,148 Gross investment income 137,036 132,580 287,596 264,826 Investment expense (1,772 ) (3,531 ) (3,473 ) (5,644 ) Net investment income $ 135,264 $ 129,049 $ 284,123 $ 259,182

Investment Funds (Tables)

Investment Funds (Tables)	6 Months Ended
	Jun. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Investment Funds	Investment funds consisted of the following: Carrying Value as of Income (Loss) from Investment Funds June 30, December 31, For the Six Months Ended June 30, (In thousands) 2017 2016 2017 2016 Real estate $ 611,598 $ 641,783 $ 19,518 $ 22,414 Energy 86,690 91,448 (8,639 ) 1,153 Hedge equity 72,685 73,913 (1,228 ) (2,030 ) Other funds 419,990 391,002 25,893 13,555 Total $ 1,190,963 $ 1,198,146 $ 35,544 $ 35,092

Real Estate Real Estate (Tables

Real Estate Real Estate (Tables)	6 Months Ended
	Jun. 30, 2017
Real Estate [Abstract]
Schedule of Real Estate Investments	Investment in real estate represents directly owned property held for investment, as follows: Carrying Value June 30, December 31, (In thousands) 2017 2016 Properties in operation $ 447,721 $ 457,237 Properties under development 869,368 727,744 Total $ 1,317,089 $ 1,184,981

Loans Receivable Loans Receivab

Loans Receivable Loans Receivable (Tables)	6 Months Ended
	Jun. 30, 2017
Receivables [Abstract]
Schedule of Loans Receivable	Loans receivable are as follows: (In thousands) June 30, 2017 December 31, 2016 Amortized cost (net of valuation allowance): Real estate loans $ 82,938 $ 92,415 Commercial loans 13,126 14,383 Total $ 96,064 $ 106,798 Fair value: Real estate loans $ 82,938 $ 92,415 Commercial loans 14,628 15,884 Total $ 97,566 $ 108,299 Valuation allowance: Specific $ 1,200 $ 1,200 General 2,183 2,197 Total $ 3,383 $ 3,397 For the Three Months Ended June 30, 2017 2016 Increase in valuation allowance $ — $ 93 For the Six Months Ended June 30, 2017 2016 Increase (decrease) in valuation allowance $ (14 ) $ 661

Realized And Unrealized Inves41

Realized And Unrealized Investment Gains (Losses) (Tables)	6 Months Ended
	Jun. 30, 2017
Realized and Unrealized Investment Gains (Losses) [Abstract]
Realized and Unrealized Investment Gains (Losses)	Realized and unrealized investment gains (losses) are as follows: For the Three Months Ended June 30, For the Six Months Ended June 30, (In thousands) 2017 2016 2017 2016 Realized investment gains (losses): Fixed maturity securities: Gains $ 7,427 $ 10,110 $ 13,032 $ 33,174 Losses — (1,480 ) (3,965 ) (4,420 ) Equity securities available for sale 32,139 4,471 74,846 4,596 Investment funds (112 ) (4,793 ) 1,155 (5,253 ) Real estate (364 ) (464 ) 2,936 4,560 Other 1,363 (1,529 ) 4,797 (885 ) Net realized gains on investments sales 40,453 6,315 92,801 31,772 Other-than-temporary impairments (1) — — — (18,114 ) Net investment gains 40,453 6,315 92,801 13,658 Income tax expense (14,159 ) (2,210 ) (32,480 ) (4,780 ) After-tax net realized investment gains $ 26,294 $ 4,105 $ 60,321 $ 8,878
Unrealized Gain (Loss) on Investments	Change in unrealized investment gains (losses) of available for sale securities: Fixed maturity securities $ 56,857 $ 122,893 $ 94,841 $ 215,321 Previously impaired fixed maturity securities 743 1,874 844 1,819 Equity securities available for sale 6,176 27,814 (42,686 ) 40,950 Investment funds 4,506 4,004 5,712 12,885 Total change in unrealized investment gains 68,282 156,585 58,711 270,975 Income tax expense (24,713 ) (51,552 ) (23,973 ) (89,087 ) Noncontrolling interests (5 ) (5 ) 14 9 After-tax change in unrealized investment gains of available for sale securities $ 43,564 $ 105,028 $ 34,752 $ 181,897 ______________________ (1) There were no other than temporary impairments (OTTI) for the three and six months ended June 30, 2017, or for the three months ended June 30, 2016. OTTI for the six months ended June 30, 2016 of $18.1 million were related to common stock.

Securities In An Unrealized L42

Securities In An Unrealized Loss Position Securities In An Unrealized Loss Position (Tables)	6 Months Ended
	Jun. 30, 2017
Statement of Financial Position [Abstract]
Securities in an unrealized loss position	The following tables summarize all securities in an unrealized loss position at June 30, 2017 and December 31, 2016 by the length of time those securities have been continuously in an unrealized loss position: Less Than 12 Months 12 Months or Greater Total (In thousands) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses June 30, 2017 U.S. government and government agency $ 115,584 $ 935 $ 30,925 $ 1,200 $ 146,509 $ 2,135 State and municipal 860,362 10,961 112,597 1,468 972,959 12,429 Mortgage-backed securities 585,106 6,827 128,391 4,038 713,497 10,865 Asset-backed securities 1,424,602 6,921 75,179 3,692 1,499,781 10,613 Corporate 612,215 4,599 41,688 3,641 653,903 8,240 Foreign government 115,875 742 1,973 30 117,848 772 Fixed maturity securities 3,713,744 30,985 390,753 14,069 4,104,497 45,054 Common stocks 24,004 4,953 9,040 738 33,044 5,691 Preferred stocks — — 24,589 1,084 24,589 1,084 Equity securities available for sale 24,004 4,953 33,629 1,822 57,633 6,775 Total $ 3,737,748 $ 35,938 $ 424,382 $ 15,891 $ 4,162,130 $ 51,829 December 31, 2016 U.S. government and government agency $ 112,709 $ 1,252 $ 35,450 $ 1,341 $ 148,159 $ 2,593 State and municipal 1,562,614 35,553 133,034 4,885 1,695,648 40,438 Mortgage-backed securities 625,903 11,103 109,066 4,828 734,969 15,931 Asset-backed securities 1,010,836 5,340 201,693 6,601 1,212,529 11,941 Corporate 1,035,245 13,448 65,147 7,470 1,100,392 20,918 Foreign government 213,246 1,985 24,820 777 238,066 2,762 Fixed maturity securities 4,560,553 68,681 569,210 25,902 5,129,763 94,583 Common stocks 336 22 8,755 1,024 9,091 1,046 Preferred stocks — — 22,034 3,639 22,034 3,639 Equity securities available for sale 336 22 30,789 4,663 31,125 4,685 Total $ 4,560,889 $ 68,703 $ 599,999 $ 30,565 $ 5,160,888 $ 99,268
Non-Investment Grade Fixed Maturity Securities	Fixed Maturity Securities – A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at June 30, 2017 is presented in the table below: ($ in thousands) Number of Securities Aggregate Fair Value Gross Unrealized Loss Foreign government 3 $ 9,655 $ 250 Mortgage-backed securities 6 6,239 215 Asset-backed securities 4 3,299 137 Corporate 2 2,922 232 Total 15 $ 22,115 $ 834

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Assets And Liabilities Measured At Fair value, On A Recurring Basis	The following tables present the assets and liabilities measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016 by level: (In thousands) Total Level 1 Level 2 Level 3 June 30, 2017 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 443,951 $ — $ 443,951 $ — State and municipal 4,442,811 — 4,442,811 — Mortgage-backed securities 1,191,907 — 1,191,907 — Asset-backed securities 2,192,030 — 2,191,857 173 Corporate 4,271,402 — 4,271,402 — Foreign government 892,299 — 892,299 — Total fixed maturity securities available for sale 13,434,400 — 13,434,227 173 Equity securities available for sale: Common stocks 447,600 438,560 — 9,040 Preferred stocks 165,207 — 161,545 3,662 Total equity securities available for sale 612,807 438,560 161,545 12,702 Arbitrage trading account 634,016 329,631 304,385 — Total $ 14,681,223 $ 768,191 $ 13,900,157 $ 12,875 Liabilities: Trading account securities sold but not yet purchased $ 62,860 $ 62,855 $ 5 $ — December 31, 2016 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 513,802 $ — $ 513,802 $ — State and municipal 4,519,503 — 4,519,503 — Mortgage-backed securities 1,189,645 — 1,189,645 — Asset-backed securities 1,907,860 — 1,907,677 183 Corporate 4,068,527 — 4,068,527 — Foreign government 902,805 — 902,805 — Total fixed maturity securities available for sale 13,102,142 — 13,101,959 183 Equity securities available for sale: Common stocks 445,858 429,647 7,457 8,754 Preferred stocks 223,342 — 219,680 3,662 Total equity securities available for sale 669,200 429,647 227,137 12,416 Arbitrage trading account 299,999 224,623 75,376 — Total $ 14,071,341 $ 654,270 $ 13,404,472 $ 12,599 Liabilities: Trading account securities sold but not yet purchased $ 51,179 $ 51,089 $ 90 $ —
Summarize Changes In Level 3 Assets	The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2017 and for the year ended December 31, 2016 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers Ending Balance In / (Out) Six Months Ended June 30, 2017: Assets: Fixed maturities securities available for sale: Asset-backed securities $ 183 $ 2 $ 16 $ — $ — $ (28 ) $ — $ — $ 173 Corporate — — — — — — — — — Total 183 2 16 — — (28 ) — — 173 Equity securities available for sale: Common stocks 8,754 — 286 — — — — — 9,040 Preferred stocks 3,662 — — — — — — — 3,662 Total 12,416 — 286 — — — — — 12,702 Arbitrage trading account — (78 ) 78 — — — — — — Total $ 12,599 $ (76 ) $ 380 $ — $ — $ (28 ) $ — $ — $ 12,875 Year ended December 31, 2016: Assets: Fixed maturities securities available for sale: Asset-backed securities $ 199 $ 3 $ 16 $ — $ — $ — $ (35 ) $ — $ 183 Corporate 154 177 — — — (331 ) — — — Total 353 180 16 — — (331 ) (35 ) — 183 Equity securities available for sale: Common stocks 7,829 — 160 — 765 — — — 8,754 Preferred stocks 3,624 38 — — — — — — 3,662 Total 11,453 38 160 — 765 — — — 12,416 Arbitrage trading account 176 (176 ) — — — — — — — Total $ 11,982 $ 42 $ 176 $ — $ 765 $ (331 ) $ (35 ) $ — $ 12,599

Reserves for Loss and Loss Ex44

Reserves for Loss and Loss Expenses (Tables)	6 Months Ended
	Jun. 30, 2017
Insurance [Abstract]
Reserve Balances	The table below provides a reconciliation of the beginning and ending reserve balances: June 30, (In thousands) 2017 2016 Net reserves at beginning of year $ 9,590,265 $ 9,244,872 Net provision for losses and loss expenses: Claims occurring during the current year (1) 1,926,394 1,878,458 Decrease in estimates for claims occurring in prior years (2) (3) (6,458 ) (15,511 ) Loss reserve discount accretion 24,366 23,536 Total 1,944,302 1,886,483 Net payments for claims: Current year 315,437 480,601 Prior year 1,432,828 1,188,704 Total 1,748,265 1,669,305 Foreign currency translation 37,097 (19,768 ) Net reserves at end of period 9,823,399 9,442,282 Ceded reserve at end of period 1,500,868 1,455,594 Gross reserves at end of period $ 11,324,267 $ 10,897,876 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $ 11,349,000 and $ 9,402,000 in 2017 and 2016, respectively. (2) The decrease in estimates for claims occurring in prior years is net of loss reserve discount. On an undiscounted basis, the estimates for claims occurring in prior years decreased by $ 14,873,000 and $ 21,696,000 in 2017 and 2016, respectively. (3) For certain retrospectively rated insurance policies and reinsurance agreements, reserve development is offset by additional or return premiums. Favorable development, net of additional and return premiums, was $24 million and $29 million as of June 30, 2017 and 2016, respectively.

Fair Value of Financial Instr45

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Carrying Amounts And Estimated Fair Values Of Financial Instruments	The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: June 30, 2017 December 31, 2016 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,514,085 $ 13,530,606 $ 13,190,668 $ 13,204,814 Equity securities available for sale 612,807 612,807 669,200 669,200 Arbitrage trading account 634,016 634,016 299,999 299,999 Loans receivable 96,064 97,566 106,798 108,299 Cash and cash equivalents 788,354 788,354 795,285 795,285 Trading account receivables from brokers and clearing organizations 164,696 164,696 484,593 484,593 Liabilities: Due to broker 124,428 124,428 19,416 19,416 Trading account securities sold but not yet purchased 62,860 62,860 51,179 51,179 Subordinated debentures 727,924 786,857 727,630 687,504 Senior notes and other debt 1,759,115 1,952,275 1,760,595 1,914,727

Reinsurance (Tables)

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2017
Insurance [Abstract]
Reinsurance Financial Information	The following is a summary of reinsurance financial information: For the Three Months For the Six Months Ended June 30, Ended June 30, (In thousands) 2017 2016 2017 2016 Written premiums: Direct $ 1,727,014 $ 1,708,535 $ 3,448,076 $ 3,417,664 Assumed 160,139 230,830 375,283 477,398 Ceded (322,902 ) (296,796 ) (612,270 ) (588,771 ) Total net premiums written $ 1,564,251 $ 1,642,569 $ 3,211,089 $ 3,306,291 Earned premiums: Direct $ 1,666,938 $ 1,609,644 $ 3,280,302 $ 3,177,712 Assumed 193,683 225,643 402,310 444,009 Ceded (291,918 ) (275,494 ) (543,868 ) (534,593 ) Total net premiums earned $ 1,568,703 $ 1,559,793 $ 3,138,744 $ 3,087,128 Ceded losses and loss expenses incurred $ 142,609 $ 167,265 $ 177,801 $ 294,194 Ceded commissions earned $ 57,752 $ 50,172 $ 114,302 $ 96,494

Restricted Stock Units (Tables)

Restricted Stock Units (Tables)	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary Of Restricted Stock Units Issued	A summary of RSUs issued in the six months ended June 30, 2017 and 2016 follows: ($ in thousands) Units Fair Value 2017 6,020 $ 405 2016 17,654 $ 964

Business Segments (Tables)

Business Segments (Tables)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Financial Information Of Company Operating Segments	Summary financial information about the Company's reporting segments is presented in the following tables. Income (loss) before income taxes by segment includes allocated investment income. Identifiable assets by segment are those assets used in or allocated to the operation of each segment. Revenues (In thousands) Earned Premiums Investment Income Other Total (1) Pre-Tax Income (Loss) Net Income (Loss) to Common Stockholders Three months ended June 30, 2017 Insurance $ 1,415,586 $ 102,719 $ 22,984 $ 1,541,289 $ 186,134 $ 124,442 Reinsurance 153,117 21,491 — 174,608 14,771 10,324 Corporate, other and eliminations (2) — 11,054 80,645 91,699 (80,397 ) (52,056 ) Net investment gains — — 40,453 40,453 40,453 26,294 Total $ 1,568,703 $ 135,264 $ 144,082 $ 1,848,049 $ 160,961 $ 109,004 Three months ended June 30, 2016 Insurance $ 1,390,744 $ 94,155 $ 27,603 $ 1,512,502 $ 176,500 $ 119,135 Reinsurance 169,049 25,372 — 194,421 23,834 16,681 Corporate, other and eliminations (2) — 9,522 133,154 142,676 (48,335 ) (30,954 ) Net investment gains — — 6,315 6,315 6,315 4,105 Total $ 1,559,793 $ 129,049 $ 167,072 $ 1,855,914 $ 158,314 $ 108,967 Six months ended June 30, 2017: Insurance $ 2,828,755 214,628 $ 41,271 $ 3,084,654 $ 386,127 $ 257,458 Reinsurance 309,989 46,269 — 356,258 19,364 13,983 Corporate, other and eliminations (2) — 23,226 161,528 184,754 (153,034 ) (99,311 ) Net investment gains — — 92,801 92,801 92,801 60,321 Total $ 3,138,744 $ 284,123 $ 295,600 $ 3,718,467 $ 345,258 $ 232,451 Six months ended June 30, 2016: Insurance $ 2,757,350 $ 193,605 $ 54,396 $ 3,005,351 $ 376,153 $ 253,639 Reinsurance 329,778 49,552 — 379,330 51,893 36,070 Corporate, other and eliminations (2) — 16,025 248,761 264,786 (108,714 ) (70,110 ) Net investment gains — — 13,658 13,658 13,658 8,878 Total $ 3,087,128 $ 259,182 $ 316,815 $ 3,663,125 $ 332,990 $ 228,477 _________________ (1) Revenues for Insurance from foreign countries for the three months ended June 30, 2017 and 2016 were $168 million and $179 million and for the six months ended June 30, 2017 and 2016 were $347 million and $359 million , respectively. Revenues for Reinsurance from foreign countries for the three months ended June 30, 2017 and 2016 were both $50 million and for the six months ended June 30, 2017 and 2016 were $101 million and $105 million , respectively. (2) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments.
Identifiable Assets By Segment	Identifiable Assets (In thousands) June 30, 2017 December 31, 2016 Insurance $ 18,687,170 $ 19,137,758 Reinsurance 3,085,961 2,524,338 Corporate, other and eliminations 2,220,360 1,687,980 Consolidated $ 23,993,491 $ 23,350,076
Net Premiums Earned By Major Line Of Business	Net premiums earned by major line of business are as follows: For the Three Months For the Six Months Ended June 30, Ended June 30, (In thousands) 2017 2016 2017 2016 Insurance: Other liability $ 460,059 $ 433,472 $ 911,889 $ 847,000 Workers’ compensation 366,950 344,736 728,086 688,317 Short-tail lines (1) 290,696 322,493 599,930 649,570 Commercial automobile 161,526 159,892 319,653 316,709 Professional liability 136,355 130,151 269,197 255,754 Total Insurance 1,415,586 1,390,744 2,828,755 2,757,350 Reinsurance: Casualty 93,212 100,113 187,952 204,418 Property 59,905 68,936 122,037 125,360 Total Reinsurance 153,117 169,049 309,989 329,778 Total $ 1,568,703 $ 1,559,793 $ 3,138,744 $ 3,087,128 ______________ (1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

General (Details)

General (Details)	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Federal Income Tax Rate	35.00%

Per Share Data (Narrative) (Det

Per Share Data (Narrative) (Details)	6 Months Ended
	Jun. 30, 2017shares
Earnings Per Share [Abstract]
Weighted average number of shares held in grantor trust	4,087,731

Per Share Data (Weighted Averag

Per Share Data (Weighted Average Number of Common Shares Used In the Computation of Basic and Diluted Earnings per Share) (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Basic (shares)	125,334	122,616	123,623	122,698
Diluted (shares)	128,601	128,575	128,546	128,562

Acquisitions_Dispositions (Narr

Acquisitions/Dispositions (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended
	Mar. 31, 2017	Feb. 29, 2016
Business Combinations [Abstract]
Ownership interest acquired (as percent)	89.50%	85.00%
Consideration transferred to acquire interest	$ 72.5	$ 42.3

Acquisitions_Dispositions (Deta

Acquisitions/Dispositions (Details) $ in Thousands	Mar. 31, 2017USD ($)
Business Combinations [Abstract]
Cash and cash equivalents	$ 1,154
Real estate, furniture and equipment	6,434
Goodwill and other intangibles assets	62,406
Other assets	9,417
Total assets acquired	79,411
Other liabilities assumed	(1,911)
Noncontrolling interest	(5,000)
Net assets acquired	$ 72,500

Consolidated Statements of Co54

Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period			$ 55,568
Other comprehensive income	$ 63,844	$ 49,163	77,748	$ 123,971
End of period	133,302		133,302
Net realized investment gains	40,453	6,315	92,801	31,772
Income before income taxes	160,961	158,314	345,258	332,990
Tax effect	(51,388)	(49,408)	(111,011)	(103,837)
Net income before noncontrolling interests	109,573	108,906	234,247	229,153
Net change in period	20,247	(55,870)	42,982	(57,917)
Other comprehensive income (loss), pre-tax	88,529		101,693
Other comprehensive income (loss), tax effect	(24,685)		(23,945)
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	69,491	8,124	55,568	(66,698)
Other comprehensive income before reclassifications	89,562	57,679	132,291	133,874
Amounts reclassified from AOCI	(25,718)	(8,516)	(54,543)	(9,903)
Other comprehensive income	63,844	49,163	77,748	123,971
Unrealized investment gain related to non-controlling interest	(33)	(5)	(14)	9
End of period	133,302	57,282	133,302	57,282
Other comprehensive income (loss), pre-tax		100,735		213,078
Other comprehensive income (loss), tax effect		(51,572)		(89,107)
Accumulated Other Comprehensive Income | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	(39,566)	(13,101)	(83,912)	(15,235)
Tax effect	13,848	4,585	29,369	5,332
Net income before noncontrolling interests	(25,718)	(8,516)	(54,543)	(9,903)
Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	418,342	257,564	427,154	180,695
Other comprehensive income before reclassifications	69,315	113,549	89,309	191,791
Amounts reclassified from AOCI	(25,718)	(8,516)	(54,543)	(9,903)
Other comprehensive income	43,597	105,033	34,766	181,888
Unrealized investment gain related to non-controlling interest	(33)	(5)	(14)	9
End of period	461,906	362,592	461,906	362,592
Unrealized investment gains, pre-tax	68,282	156,605	58,711	270,995
Unrealized investment gains, tax effect	(24,685)	(51,572)	(23,945)	(89,107)
Unrealized investment gains, after-tax amounts	43,597	105,033	34,766	181,888
Unrealized Investment Gains (Losses) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net realized investment gains	(39,566)	(13,101)	(83,912)	(15,235)
Tax effect	13,848	4,585	29,369	5,332
Net income before noncontrolling interests	(25,718)	(8,516)	(54,543)	(9,903)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(348,851)	(249,440)	(371,586)	(247,393)
Other comprehensive income before reclassifications	20,247	(55,870)	42,982	(57,917)
Amounts reclassified from AOCI	0	0	0	0
Other comprehensive income	20,247	(55,870)	42,982	(57,917)
Unrealized investment gain related to non-controlling interest	0	0	0	0
End of period	(328,604)	(305,310)	(328,604)	(305,310)
Currency translation adjustment, pre-tax	20,247	(55,870)	42,982	(57,917)
Currency translation adjustment, tax effect	0	0	0	0
Net change in period	20,247	(55,870)	42,982	(57,917)
Currency Translation Adjustments | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	0	0	0	0
Tax effect	0	0	0	0
Net income before noncontrolling interests	$ 0	$ 0	$ 0	$ 0

Statements of Cash Flow (Detail

Statements of Cash Flow (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Interest payments	$ 72,528	$ 64,109
Income taxes paid	$ 145,123	$ 86,695

Investments in Fixed Maturity56

Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Total held to maturity, Amortized Cost	$ 79,685,000	$ 88,526,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	16,521,000	14,146,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0	0
Total held to maturity, Fair Value	96,206,000	102,672,000
Total held to maturity, Carrying Value	79,685,000	88,526,000
Total available for sale, Amortized Cost	13,107,838,000	12,869,809,000
Total available for sale, Gross Unrealized Gains	371,616,000	326,916,000
Total available for sale, Gross Unrealized Losses	(45,054,000)	(94,583,000)
Total available for sale, Fair Value	13,434,400,000	13,102,142,000
Total available for sale, Carrying Value	13,434,400,000	13,102,142,000
Total investments in fixed maturity securities, Amortized Value	13,187,523,000	12,958,335,000
Total investments in fixed maturity securities, Gross Unrealized Gains	388,137,000	341,062,000
Total investments in fixed maturity securities, Gross Unrealized Losses	(45,054,000)	(94,583,000)
Total investments in fixed maturity securities, Fair Value	13,530,606,000	13,204,814,000
Total investments in fixed maturity securities, Carrying Value	$ 13,514,085,000	13,190,668,000
Minimum ownership of Common stockholders equity	10.00%
U.S. government and government agency
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	$ 432,145,000	496,187,000
Total available for sale, Gross Unrealized Gains	13,941,000	20,208,000
Total available for sale, Gross Unrealized Losses	(2,135,000)	(2,593,000)
Total available for sale, Fair Value	443,951,000	513,802,000
Total available for sale, Carrying Value	443,951,000	513,802,000
Special revenue
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	2,770,582,000	2,791,211,000
Total available for sale, Gross Unrealized Gains	80,887,000	58,559,000
Total available for sale, Gross Unrealized Losses	(9,471,000)	(26,315,000)
Total available for sale, Fair Value	2,841,998,000	2,823,455,000
Total available for sale, Carrying Value	2,841,998,000	2,823,455,000
State general obligation
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	471,980,000	524,682,000
Total available for sale, Gross Unrealized Gains	21,596,000	16,964,000
Total available for sale, Gross Unrealized Losses	(1,359,000)	(5,139,000)
Total available for sale, Fair Value	492,217,000	536,507,000
Total available for sale, Carrying Value	492,217,000	536,507,000
Pre-refunded
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	312,535,000	356,535,000
Total available for sale, Gross Unrealized Gains	21,825,000	19,181,000
Total available for sale, Gross Unrealized Losses	(216,000)	(165,000)
Total available for sale, Fair Value	334,144,000	375,551,000
Total available for sale, Carrying Value	334,144,000	375,551,000
Corporate backed
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	384,609,000	410,933,000
Total available for sale, Gross Unrealized Gains	10,609,000	6,172,000
Total available for sale, Gross Unrealized Losses	(916,000)	(6,452,000)
Total available for sale, Fair Value	394,302,000	410,653,000
Total available for sale, Carrying Value	394,302,000	410,653,000
Local general obligation
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	354,110,000	360,022,000
Total available for sale, Gross Unrealized Gains	26,507,000	15,682,000
Total available for sale, Gross Unrealized Losses	(467,000)	(2,367,000)
Total available for sale, Fair Value	380,150,000	373,337,000
Total available for sale, Carrying Value	380,150,000	373,337,000
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	4,293,816,000	4,443,383,000
Total available for sale, Gross Unrealized Gains	161,424,000	116,558,000
Total available for sale, Gross Unrealized Losses	(12,429,000)	(40,438,000)
Total available for sale, Fair Value	4,442,811,000	4,519,503,000
Total available for sale, Carrying Value	4,442,811,000	4,519,503,000
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	1,188,238,000	1,189,841,000
Total available for sale, Gross Unrealized Gains	14,534,000	15,735,000
Total available for sale, Gross Unrealized Losses	(10,865,000)	(15,931,000)
Total available for sale, Fair Value	1,191,907,000	1,189,645,000
Total available for sale, Carrying Value	1,191,907,000	1,189,645,000
Residential
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	997,886,000	1,034,301,000
Total available for sale, Gross Unrealized Gains	13,968,000	15,431,000
Total available for sale, Gross Unrealized Losses	(9,608,000)	(12,950,000)
Total available for sale, Fair Value	1,002,246,000	1,036,782,000
Total available for sale, Carrying Value	1,002,246,000	1,036,782,000
Gross unrealized gains (losses) related to securities	25,220	(818,691)
Commercial
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	190,352,000	155,540,000
Total available for sale, Gross Unrealized Gains	566,000	304,000
Total available for sale, Gross Unrealized Losses	(1,257,000)	(2,981,000)
Total available for sale, Fair Value	189,661,000	152,863,000
Total available for sale, Carrying Value	189,661,000	152,863,000
Asset-backed
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	2,196,114,000	1,913,830,000
Total available for sale, Gross Unrealized Gains	6,529,000	5,971,000
Total available for sale, Gross Unrealized Losses	(10,613,000)	(11,941,000)
Total available for sale, Fair Value	2,192,030,000	1,907,860,000
Total available for sale, Carrying Value	2,192,030,000	1,907,860,000
Corporate
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	4,143,227,000	3,967,795,000
Total available for sale, Gross Unrealized Gains	136,415,000	121,650,000
Total available for sale, Gross Unrealized Losses	(8,240,000)	(20,918,000)
Total available for sale, Fair Value	4,271,402,000	4,068,527,000
Total available for sale, Carrying Value	4,271,402,000	4,068,527,000
Industrial
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	2,394,374,000	2,315,567,000
Total available for sale, Gross Unrealized Gains	73,884,000	71,007,000
Total available for sale, Gross Unrealized Losses	(2,717,000)	(7,174,000)
Total available for sale, Fair Value	2,465,541,000	2,379,400,000
Total available for sale, Carrying Value	2,465,541,000	2,379,400,000
Financial
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	1,444,201,000	1,369,001,000
Total available for sale, Gross Unrealized Gains	49,524,000	39,543,000
Total available for sale, Gross Unrealized Losses	(4,929,000)	(11,270,000)
Total available for sale, Fair Value	1,488,796,000	1,397,274,000
Total available for sale, Carrying Value	1,488,796,000	1,397,274,000
Utilities
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	255,777,000	229,154,000
Total available for sale, Gross Unrealized Gains	12,725,000	10,801,000
Total available for sale, Gross Unrealized Losses	(576,000)	(2,411,000)
Total available for sale, Fair Value	267,926,000	237,544,000
Total available for sale, Carrying Value	267,926,000	237,544,000
Other
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	48,875,000	54,073,000
Total available for sale, Gross Unrealized Gains	282,000	299,000
Total available for sale, Gross Unrealized Losses	(18,000)	(63,000)
Total available for sale, Fair Value	49,139,000	54,309,000
Total available for sale, Carrying Value	49,139,000	54,309,000
Foreign
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	854,298,000	858,773,000
Total available for sale, Gross Unrealized Gains	38,773,000	46,794,000
Total available for sale, Gross Unrealized Losses	(772,000)	(2,762,000)
Total available for sale, Fair Value	892,299,000	902,805,000
Total available for sale, Carrying Value	892,299,000	902,805,000
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Total held to maturity, Amortized Cost	64,931,000	72,582,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	14,943,000	12,453,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0	0
Total held to maturity, Fair Value	79,874,000	85,035,000
Total held to maturity, Carrying Value	64,931,000	72,582,000
Residential
Schedule of Available-for-sale Securities [Line Items]
Total held to maturity, Amortized Cost	14,754,000	15,944,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	1,578,000	1,693,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0	0
Total held to maturity, Fair Value	16,332,000	17,637,000
Total held to maturity, Carrying Value	$ 14,754,000	$ 15,944,000

Investments In Fixed Maturity57

Investments In Fixed Maturity Securities Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 803,520
Amortized Cost, Due after one year through five years	5,237,765
Amortized Cost, Due after five years through ten years	3,169,976
Amortized Cost, Due after ten years	2,773,270
Amortized Cost, Mortgaged-backed securities	1,202,992
Total investments in fixed maturity securities, Amortized Value	13,187,523	$ 12,958,335
Fair Value, Due in one year or less	819,242
Fair Value, Due after one year through five years	5,368,120
Fair Value, Due after five years through ten years	3,311,894
Fair Value, Due after ten years	2,823,111
Fair Value, Mortgage-backed securities	1,208,239
Total investments in fixed maturity securities, Fair Value	$ 13,530,606	$ 13,204,814

Investments in Equity Securit58

Investments in Equity Securities Available for Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 206,268	$ 220,587
Gross Unrealized, Gains	413,314	453,298
Gross Unrealized, Losses	(6,775)	(4,685)
Carrying and fair value of equity securities	612,807	669,200
Common stock
Schedule of Available-for-sale Securities [Line Items]
Cost	87,185	94,998
Gross Unrealized, Gains	366,106	351,906
Gross Unrealized, Losses	(5,691)	(1,046)
Carrying and fair value of equity securities	447,600	445,858
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	119,083	125,589
Gross Unrealized, Gains	47,208	101,392
Gross Unrealized, Losses	(1,084)	(3,639)
Carrying and fair value of equity securities	$ 165,207	$ 223,342

Arbitrage Trading Account (Deta

Arbitrage Trading Account (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Arbitrage trading account	$ 634,016	$ 299,999
Short | Options held
Derivative [Line Items]
Fair value of derivative	1,000
Notional amount of derivative	73,000
Long | Options held
Derivative [Line Items]
Fair value of derivative	1,000
Notional amount of derivative	$ 32,000

Net Investment Income (Details)

Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net Investment Income [Line Items]
Gross investment income	$ 137,036	$ 132,580	$ 287,596	$ 264,826
Investment expense	(1,772)	(3,531)	(3,473)	(5,644)
Net investment income	135,264	129,049	284,123	259,182
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	116,796	108,342	229,142	217,177
Investment funds
Net Investment Income [Line Items]
Gross investment income	8,895	18,456	35,544	35,092
Arbitrage trading account
Net Investment Income [Line Items]
Gross investment income	5,457	3,252	11,817	6,442
Real estate
Net Investment Income [Line Items]
Gross investment income	5,286	1,250	9,852	3,967
Equity securities available for sale
Net Investment Income [Line Items]
Gross investment income	$ 602	$ 1,280	$ 1,241	$ 2,148

Investment Funds Investment Fun

Investment Funds Investment Funds (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Unfunded commitments	$ 354,000
Investment funds	1,190,963		$ 1,198,146
Income (Loss) from Investment Funds	35,544	$ 35,092
Real estate
Schedule of Equity Method Investments [Line Items]
Investment funds	611,598		641,783
Income (Loss) from Investment Funds	19,518	22,414
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds	86,690		91,448
Income (Loss) from Investment Funds	(8,639)	1,153
Hedge equity
Schedule of Equity Method Investments [Line Items]
Investment funds	72,685		73,913
Income (Loss) from Investment Funds	(1,228)	(2,030)
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds	419,990		$ 391,002
Income (Loss) from Investment Funds	$ 25,893	$ 13,555

Real Estate Real Estate (Detail

Real Estate Real Estate (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Real Estate [Abstract]
Properties in operation	$ 447,721	$ 457,237
Properties under development	869,368	727,744
Total	$ 1,317,089	$ 1,184,981

Real Estate Real Estate (Narrat

Real Estate Real Estate (Narrative) (Details) - USD ($)	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Real Estate [Abstract]
Accumulated depreciation and amortization on properties	$ 18,600,000		$ 14,996,000
Real estate depreciation expense	3,604,000	$ 3,279,000
Lease future minimum payments 2017	9,248,244
Lease future minimum payments 2018	27,797,511
Lease future minimum payments 2019	29,246,483
Lease future minimum payments 2020	28,527,541
Lease future minimum payments 2021	29,145,221
Lease future minimum payments 2022	28,784,655
Lease future minimum payments there after	$ 466,275,306

Loans Receivable (Details)

Loans Receivable (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	$ 96,064		$ 96,064		$ 106,798
Loans receivable	97,566		97,566		108,299
Valuation allowance, specific	1,200		1,200		1,200
Valuation allowance, general	2,183		2,183		2,197
Valuation allowance of loans receivable	3,383		3,383		3,397
Increase (decrease) in valuation allowance	0	$ 93	(14)	$ 661
Loans in nonaccrual status	4,500		4,500		5,400
Real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	82,938		82,938		92,415
Loans receivable	82,938		82,938		92,415
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	13,126		13,126		14,383
Loans receivable	$ 14,628		$ 14,628		$ 15,884

Realized and Unrealized Inves65

Realized and Unrealized Investment Gains (Losses) (Realized and unrealized investmetns gains(losses)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Realized and Unrealized Investment Gains Losses [Line Items]
Fixed maturity securities, gains	$ 7,427	$ 10,110	$ 13,032	$ 33,174
Fixed maturity securities, losses	0	(1,480)	(3,965)	(4,420)
Equity securities available for sale	32,139	4,471	74,846	4,596
Investment funds	(112)	(4,793)	1,155	(5,253)
Real estate	(364)	(464)	2,936	4,560
Other	1,363	(1,529)	4,797	(885)
Net realized gains on investments sales	40,453	6,315	92,801	31,772
Other-than-temporary impairments	0	0	0	(18,114)
Net investment gains	40,453	6,315	92,801	13,658
Income tax expense	(14,159)	(2,210)	(32,480)	(4,780)
After-tax net realized investment gains	$ 26,294	$ 4,105	$ 60,321	8,878
Common stock
Realized and Unrealized Investment Gains Losses [Line Items]
Other-than-temporary impairments				$ (18,100)

Realized and Unrealized Inves66

Realized and Unrealized Investment Gains (Losses) (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	$ 68,282	$ 156,585	$ 58,711	$ 270,975
Income tax expense	(24,713)	(51,552)	(23,973)	(89,087)
Noncontrolling interests	(5)	(5)	14	9
Total change in unrealized gains	43,564	105,028	34,752	181,897
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	56,857	122,893	94,841	215,321
Previously impaired fixed maturity securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	743	1,874	844	1,819
Equity securities available for sale
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	6,176	27,814	(42,686)	40,950
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	$ 4,506	$ 4,004	$ 5,712	$ 12,885

Securities in an Unrealized L67

Securities in an Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	$ 3,737,748	$ 4,560,889
Gross Unrealized Losses, Less than 12 Months	35,938	68,703
Fair Value, 12 Months or Greater	424,382	599,999
Gross Unrealized Losses, 12 Months or Greater	15,891	30,565
Fair Value, Total	4,162,130	5,160,888
Gross Unrealized Losses, Total	51,829	99,268
Debt securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	3,713,744	4,560,553
Gross Unrealized Losses, Less than 12 Months	30,985	68,681
Fair Value, 12 Months or Greater	390,753	569,210
Gross Unrealized Losses, 12 Months or Greater	14,069	25,902
Fair Value, Total	4,104,497	5,129,763
Gross Unrealized Losses, Total	45,054	94,583
U.S. government and government agency
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	115,584	112,709
Gross Unrealized Losses, Less than 12 Months	935	1,252
Fair Value, 12 Months or Greater	30,925	35,450
Gross Unrealized Losses, 12 Months or Greater	1,200	1,341
Fair Value, Total	146,509	148,159
Gross Unrealized Losses, Total	2,135	2,593
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	860,362	1,562,614
Gross Unrealized Losses, Less than 12 Months	10,961	35,553
Fair Value, 12 Months or Greater	112,597	133,034
Gross Unrealized Losses, 12 Months or Greater	1,468	4,885
Fair Value, Total	972,959	1,695,648
Gross Unrealized Losses, Total	12,429	40,438
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	585,106	625,903
Gross Unrealized Losses, Less than 12 Months	6,827	11,103
Fair Value, 12 Months or Greater	128,391	109,066
Gross Unrealized Losses, 12 Months or Greater	4,038	4,828
Fair Value, Total	713,497	734,969
Gross Unrealized Losses, Total	10,865	15,931
Asset-backed
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	1,424,602	1,010,836
Gross Unrealized Losses, Less than 12 Months	6,921	5,340
Fair Value, 12 Months or Greater	75,179	201,693
Gross Unrealized Losses, 12 Months or Greater	3,692	6,601
Fair Value, Total	1,499,781	1,212,529
Gross Unrealized Losses, Total	10,613	11,941
Corporate
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	612,215	1,035,245
Gross Unrealized Losses, Less than 12 Months	4,599	13,448
Fair Value, 12 Months or Greater	41,688	65,147
Gross Unrealized Losses, 12 Months or Greater	3,641	7,470
Fair Value, Total	653,903	1,100,392
Gross Unrealized Losses, Total	8,240	20,918
Foreign government
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	115,875	213,246
Gross Unrealized Losses, Less than 12 Months	742	1,985
Fair Value, 12 Months or Greater	1,973	24,820
Gross Unrealized Losses, 12 Months or Greater	30	777
Fair Value, Total	117,848	238,066
Gross Unrealized Losses, Total	772	2,762
Equity securities available for sale
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	24,004	336
Gross Unrealized Losses, Less than 12 Months	4,953	22
Fair Value, 12 Months or Greater	33,629	30,789
Gross Unrealized Losses, 12 Months or Greater	1,822	4,663
Fair Value, Total	57,633	31,125
Gross Unrealized Losses, Total	6,775	4,685
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	24,004	336
Gross Unrealized Losses, Less than 12 Months	4,953	22
Fair Value, 12 Months or Greater	9,040	8,755
Gross Unrealized Losses, 12 Months or Greater	738	1,024
Fair Value, Total	33,044	9,091
Gross Unrealized Losses, Total	5,691	1,046
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	0
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Greater	24,589	22,034
Gross Unrealized Losses, 12 Months or Greater	1,084	3,639
Fair Value, Total	24,589	22,034
Gross Unrealized Losses, Total	$ 1,084	$ 3,639

Securities In An Unrealized L68

Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands	Jun. 30, 2017USD ($)position	Dec. 31, 2016USD ($)
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	$ 4,162,130	$ 5,160,888
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	713,497	734,969
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	1,499,781	1,212,529
Corporate
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	$ 653,903	$ 1,100,392
Noninvestment Grade Investments at Loss Position
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	15
Aggregate Fair Value	$ 22,115
Gross Unrealized Loss	$ 834
Noninvestment Grade Investments at Loss Position | Foreign government
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	3
Aggregate Fair Value	$ 9,655
Gross Unrealized Loss	$ 250
Noninvestment Grade Investments at Loss Position | Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	6
Aggregate Fair Value	$ 6,239
Gross Unrealized Loss	$ 215
Noninvestment Grade Investments at Loss Position | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | position	4
Aggregate Fair Value	$ 3,299
Gross Unrealized Loss	$ 137
Noninvestment Grade Investments at Loss Position | Corporate
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	2
Aggregate Fair Value	$ 2,922
Gross Unrealized Loss	$ 232

Securities In An Unrealized L69

Securities In An Unrealized Loss Position (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)shares	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)shares	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	$ 4,162,130		$ 4,162,130		$ 5,160,888
Gross unrealized losses	51,829		51,829		99,268
Other-than-temporary impairments	0	$ 0	0	$ 18,114
Common stock
Schedule of Available-for-sale Securities [Line Items]
Other-than-temporary impairments				$ 18,100
Common stock
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses	$ 5,700		$ 5,700
Noninvestment Grade Investments
Schedule of Available-for-sale Securities [Line Items]
Number of securities | shares	1		1
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	$ 24,589		$ 24,589		22,034
Gross unrealized losses	1,084		1,084		3,639
Common stock
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	33,044		33,044		9,091
Other-than-temporary impairment, available for sale securities			33,000
Gross unrealized losses	$ 5,691		$ 5,691		$ 1,046

Fair Value Measurements (Assets

Fair Value Measurements (Assets and Liabilities Measured At Fair Value, On a Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets:
Total fixed maturity securities available for sale	$ 13,434,400	$ 13,102,142
Equity securities available for sale	612,807	669,200
Arbitrage trading account	634,016	299,999
Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	13,434,400	13,102,142
Equity securities available for sale	612,807	669,200
Arbitrage trading account	634,016	299,999
Assets, fair value disclosure	14,681,223	14,071,341
Liabilities:
Securities sold but not yet purchased	62,860	51,179
Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	443,951	513,802
Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	4,442,811	4,519,503
Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	1,191,907	1,189,645
Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	2,192,030	1,907,860
Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	4,271,402	4,068,527
Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	892,299	902,805
Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities available for sale	447,600	445,858
Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities available for sale	165,207	223,342
Level 1 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities available for sale	438,560	429,647
Arbitrage trading account	329,631	224,623
Assets, fair value disclosure	768,191	654,270
Liabilities:
Securities sold but not yet purchased	62,855	51,089
Level 1 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities available for sale	438,560	429,647
Level 1 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities available for sale	0	0
Level 2 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	13,434,227	13,101,959
Equity securities available for sale	161,545	227,137
Arbitrage trading account	304,385	75,376
Assets, fair value disclosure	13,900,157	13,404,472
Liabilities:
Securities sold but not yet purchased	5	90
Level 2 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	443,951	513,802
Level 2 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	4,442,811	4,519,503
Level 2 | Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	1,191,907	1,189,645
Level 2 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	2,191,857	1,907,677
Level 2 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	4,271,402	4,068,527
Level 2 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	892,299	902,805
Level 2 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities available for sale	0	7,457
Level 2 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities available for sale	161,545	219,680
Level 3 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	173	183
Equity securities available for sale	12,702	12,416
Arbitrage trading account	0	0
Assets, fair value disclosure	12,875	12,599
Liabilities:
Securities sold but not yet purchased	0	0
Level 3 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	173	183
Level 3 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities available for sale	9,040	8,754
Level 3 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities available for sale	$ 3,662	$ 3,662

Fair Value Measurements (Summar

Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, impairments	$ 0	$ 0
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	12,599	11,982
Assets, earnings	(76)	42
Assets, other comprehensive income	380	176
Assets, purchases	0	765
Assets, (sales)	(28)	(331)
Assets, maturities		(35)
Assets. transfers out		0
Assets, ending balance	12,875	12,599
Level 3 | Debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	183	353
Assets, earnings	2	180
Assets, other comprehensive income	16	16
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(28)	(331)
Assets, maturities		(35)
Assets. transfers out	0	0
Assets, ending balance	173	183
Level 3 | Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	183	199
Assets, earnings	2	3
Assets, other comprehensive income	16	16
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(28)	0
Assets, maturities	0	(35)
Assets. transfers out	0	0
Assets, ending balance	173	183
Level 3 | Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	0	154
Assets, earnings	0	177
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	0	(331)
Assets. transfers out	0	0
Assets, ending balance	0	0
Level 3 | Equity securities available for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	12,416	11,453
Assets, earnings	0	38
Assets, other comprehensive income	286	160
Assets, impairments	0	0
Assets, purchases	0	765
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	12,702	12,416
Level 3 | Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	8,754	7,829
Assets, earnings	0	0
Assets, other comprehensive income	286	160
Assets, impairments	0	0
Assets, purchases	0	765
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	9,040	8,754
Level 3 | Preferred stocks
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	3,662	3,624
Assets, earnings	0	38
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	3,662	3,662
Level 3 | Arbitrage trading account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	0	176
Assets, earnings	(78)	(176)
Assets, other comprehensive income	78	0
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	$ 0	$ 0

Reserves for Loss and Loss Ex72

Reserves for Loss and Loss Expenses (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of year	$ 9,590,265	$ 9,244,872
Net provision for losses and loss expenses:
Claims occurring during the current year	1,926,394	1,878,458
Decrease in estimates for claims occurring in prior years	(6,458)	(15,511)
Loss reserve discount accretion	24,366	23,536
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	1,944,302	1,886,483
Net payments for claims:
Current year	315,437	480,601
Prior year	1,432,828	1,188,704
Total	1,748,265	1,669,305
Foreign currency translation	37,097	(19,768)
Net reserves at end of period	9,823,399	9,442,282
Ceded reserve at end of period	1,500,868	1,455,594
Gross reserves at end of period	$ 11,324,267	$ 10,897,876	$ 11,197,195

Reserves for Loss and Loss Ex73

Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Net of loss reserve discounts	$ 11,349		$ 9,402
Decrease in estimates for claims	14,873		$ 21,696
Adjustment expense	23,600	$ 28,700
Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Adjustment expense	49,400	24,800
Reinsurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Adjustment expense	$ 25,800	$ 3,900

Fair Value of Financial Instr74

Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets:
Arbitrage trading account	$ 634,016	$ 299,999
Loans receivable	97,566	108,299
Carrying Value
Assets:
Fixed maturity securities	13,514,085	13,190,668
Equity securities available for sale	612,807	669,200
Arbitrage trading account	634,016	299,999
Loans receivable	96,064	106,798
Cash and cash equivalents	788,354	795,285
Trading account receivables from brokers and clearing organizations	164,696	484,593
Liabilities:
Due to broker	124,428	19,416
Trading account securities sold but not yet purchased	62,860	51,179
Subordinated debentures	727,924	727,630
Senior notes and other debt	1,759,115	1,760,595
Fair Value
Assets:
Fixed maturity securities	13,530,606	13,204,814
Equity securities available for sale	612,807	669,200
Arbitrage trading account	634,016	299,999
Loans receivable	97,566	108,299
Cash and cash equivalents	788,354	795,285
Trading account receivables from brokers and clearing organizations	164,696	484,593
Liabilities:
Due to broker	124,428	19,416
Trading account securities sold but not yet purchased	62,860	51,179
Subordinated debentures	786,857	687,504
Senior notes and other debt	$ 1,952,275	$ 1,914,727

Reinsurance (Details)

Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Written premiums:
Written premiums, direct	$ 1,727,014	$ 1,708,535	$ 3,448,076	$ 3,417,664
Written premiums, assumed	160,139	230,830	375,283	477,398
Written premiums, ceded	(322,902)	(296,796)	(612,270)	(588,771)
Total net premiums written	1,564,251	1,642,569	3,211,089	3,306,291
Earned premiums:
Earned premiums, direct	1,666,938	1,609,644	3,280,302	3,177,712
Earned premiums, assumed	193,683	225,643	402,310	444,009
Earned premiums, ceded	(291,918)	(275,494)	(543,868)	(534,593)
Net premiums earned	1,568,703	1,559,793	3,138,744	3,087,128
Ceded losses and loss expenses incurred	142,609	167,265	177,801	294,194
Ceded commissions earned	57,752	$ 50,172	114,302	$ 96,494
Uncollectible reinsurance	$ 1,000		$ 1,000		$ 1,000

Restricted Stock Units (Summary

Restricted Stock Units (Summary of Restricted Stock Units Issued) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Share based compensation expense	$ 21,000	$ 16,000
Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Restricted stock units (in units)	6,020	17,654,000
Fair Value	$ 405	$ 964
Minimum | Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Award vesting period	3 years
Maximum | Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Award vesting period	5 years

Business Segments (Financial In

Business Segments (Financial Information of Company Operating Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Earned Premiums	$ 1,568,703	$ 1,559,793	$ 3,138,744	$ 3,087,128
Investment Income and Funds	135,264	129,049	284,123	259,182
Other	144,082	167,072	295,600	316,815
Total revenues	1,848,049	1,855,914	3,718,467	3,663,125
Pre-Tax Income (Loss)	160,961	158,314	345,258	332,990
Net Income (Loss) to Common Stockholders	109,004	108,967	232,451	228,477
Net investment gains	40,453	6,315	92,801	13,658
Net investment gains, net of tax	26,294	4,105	60,321	8,878
Corporate, other and eliminations
Segment Reporting Information [Line Items]
Earned Premiums	0	0	0	0
Investment Income and Funds	11,054	9,522	23,226	16,025
Other	80,645	133,154	161,528	248,761
Total revenues	91,699	142,676	184,754	264,786
Pre-Tax Income (Loss)	(80,397)	(48,335)	(153,034)	(108,714)
Net Income (Loss) to Common Stockholders	(52,056)	(30,954)	(99,311)	(70,110)
Insurance
Segment Reporting Information [Line Items]
Earned Premiums	1,415,586	1,390,744	2,828,755	2,757,350
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums	1,415,586	1,390,744	2,828,755	2,757,350
Investment Income and Funds	102,719	94,155	214,628	193,605
Other	22,984	27,603	41,271	54,396
Total revenues	1,541,289	1,512,502	3,084,654	3,005,351
Pre-Tax Income (Loss)	186,134	176,500	386,127	376,153
Net Income (Loss) to Common Stockholders	124,442	119,135	257,458	253,639
Reinsurance
Segment Reporting Information [Line Items]
Earned Premiums	153,117	169,049	309,989	329,778
Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums	153,117	169,049	309,989	329,778
Investment Income and Funds	21,491	25,372	46,269	49,552
Other	0	0	0	0
Total revenues	174,608	194,421	356,258	379,330
Pre-Tax Income (Loss)	14,771	23,834	19,364	51,893
Net Income (Loss) to Common Stockholders	10,324	16,681	13,983	36,070
Re-insurance - International | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	50,000	50,000	101,000	105,000
Net investment gains
Segment Reporting Information [Line Items]
Earned Premiums	0	0
Investment Income and Funds	0	0		0
Insurance-International Segment | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	$ 168,000	$ 179,000	$ 347,000	$ 359,000

Business Segments (Identifiable

Business Segments (Identifiable Assets by Segment) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 23,993,491	$ 23,350,076
Operating Segments | Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	18,687,170	19,137,758
Operating Segments | Reinsurance
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	3,085,961	2,524,338
Corporate, other and eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 2,220,360	$ 1,687,980

Business Segments (Net Premiums

Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue from External Customer [Line Items]
Premiums Earned, Net	$ 1,568,703	$ 1,559,793	$ 3,138,744	$ 3,087,128
Insurance
Revenue from External Customer [Line Items]
Premiums Earned, Net	1,415,586	1,390,744	2,828,755	2,757,350
Insurance | Other liability
Revenue from External Customer [Line Items]
Premiums Earned, Net	460,059	433,472	911,889	847,000
Insurance | Workers’ compensation
Revenue from External Customer [Line Items]
Premiums Earned, Net	366,950	344,736	728,086	688,317
Insurance | Property
Revenue from External Customer [Line Items]
Premiums Earned, Net	290,696	322,493	599,930	649,570
Insurance | Commercial automobile
Revenue from External Customer [Line Items]
Premiums Earned, Net	161,526	159,892	319,653	316,709
Insurance | Professional liability
Revenue from External Customer [Line Items]
Premiums Earned, Net	136,355	130,151	269,197	255,754
Reinsurance
Revenue from External Customer [Line Items]
Premiums Earned, Net	153,117	169,049	309,989	329,778
Reinsurance | Property
Revenue from External Customer [Line Items]
Premiums Earned, Net	59,905	68,936	122,037	125,360
Reinsurance | Casualty
Revenue from External Customer [Line Items]
Premiums Earned, Net	$ 93,212	$ 100,113	$ 187,952	$ 204,418

Subsequent Event (Details)

Subsequent Event (Details) $ in Millions	1 Months Ended
	Jul. 31, 2017USD ($)
Subsequent event
Subsequent Event [Line Items]
Pre-tax realized gain from sale of wholly owned non insurance business	$ 120