Reinsurance Group of America (RGA) 10-Q 2 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document And Entitiy Information [Abstract]
Document Type	10-Q
Document period end date	Sep. 30, 2017
Amendment flag	false
Entity registrant name	REINSURANCE GROUP OF AMERICA INC
Entity central index key	898,174
Entity current reporting status	Yes
Entity voluntary filers	No
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Entity well-known seasoned issuer	Yes
Common Shares Outstanding		64,404,061
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fixed maturity securities:
Available-for-sale at fair value (amortized cost of $33,889,968 and $30,211,787)	$ 36,381,742	$ 32,093,625
Mortgage loans on real estate (net of allowances of $9,137 and $7,685)	4,322,329	3,775,522
Policy loans	1,340,146	1,427,602
Funds withheld at interest	6,020,336	5,875,919
Short-term investments	80,582	76,710
Other invested assets	1,532,523	1,591,940
Total investments	49,677,658	44,841,318
Cash and cash equivalents	1,204,590	1,200,718
Accrued investment income	420,111	347,173
Premiums receivable and other reinsurance balances	2,411,777	1,930,755
Reinsurance ceded receivables	779,118	683,972
Deferred policy acquisition costs	3,315,237	3,338,605
Other assets	885,540	755,338
Total assets	58,694,031	53,097,879
Liabilities and Stockholders’ Equity
Future policy benefits	21,084,562	19,581,573
Interest-sensitive contract liabilities	16,370,090	14,029,354
Other policy claims and benefits	4,899,367	4,263,026
Other reinsurance balances	415,692	388,989
Deferred income taxes	3,180,545	2,770,640
Other liabilities	1,061,352	1,041,880
Long-term debt	2,788,480	3,088,635
Collateral finance and securitization notes	796,825	840,700
Total liabilities	50,596,913	46,004,797
Commitments and contingent liabilities (See Note 8)
Stockholders’ Equity:
Preferred stock - par value $.01 per share, 10,000,000 shares authorized, no shares issued or outstanding	0	0
Common stock - par value $.01 per share, 140,000,000 shares authorized, 79,137,758 shares issued at September 30, 2017 and December 31, 2016	791	791
Additional paid-in capital	1,865,699	1,848,611
Retained earnings	5,712,590	5,199,130
Treasury stock, at cost - 14,769,487 and 14,835,256 shares	(1,107,719)	(1,094,779)
Accumulated other comprehensive income	1,625,757	1,139,329
Total stockholders’ equity	8,097,118	7,093,082
Total liabilities and stockholders’ equity	$ 58,694,031	$ 53,097,879

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS PARENTHETICAL - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available for Sale at Fair value - Amortized cost	$ 33,889,968	$ 30,211,787
Preferred stock par value (per share)	$ 0.01	$ 0.01
Preferred stock shares authorized	10,000,000	10,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common stock par value (per share)	$ 0.01	$ 0.01
Common stock shares authorized	140,000,000	140,000,000
Common Stock, Shares, Issued	79,137,758	79,137,758
Common stock shares outstanding	64,368,271	64,302,502
Treasury stock, shares	14,769,487	14,835,256
Allowances for Loan and Lease Losses, Real Estate	$ 9,137	$ 7,685

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Net premiums	$ 2,489,797	$ 2,251,758	$ 7,335,944	$ 6,755,708
Investment income, net of related expenses	556,918	489,727	1,589,820	1,414,659
Investment related gains (losses), net:
Other-than-temporary impairments on fixed maturity securities	(390)	0	(20,980)	(34,663)
Other investment related gains (losses), net	23,043	86,624	160,451	118,665
Total investment related gains (losses), net	22,653	86,624	139,471	84,002
Other revenues	75,942	72,468	218,091	197,844
Total revenues	3,145,310	2,900,577	9,283,326	8,452,213
Benefits and Expenses:
Claims and other policy benefits	2,100,680	1,993,064	6,371,188	5,877,330
Interest credited	126,099	116,848	349,068	300,602
Policy acquisition costs and other insurance expenses	365,424	300,962	1,064,645	940,406
Other operating expenses	168,417	152,556	481,279	469,875
Interest expense	36,836	43,063	108,590	96,201
Collateral finance and securitization expense	7,692	6,484	21,235	19,396
Total benefits and expenses	2,805,148	2,612,977	8,396,005	7,703,810
Income before income taxes	340,162	287,600	887,321	748,403
Provision for income taxes	112,571	88,881	282,028	237,109
Net income	$ 227,591	$ 198,719	$ 605,293	$ 511,294
Earnings per share:
Basic earnings per share	$ 3.53	$ 3.10	$ 9.39	$ 7.95
Diluted earnings per share	3.47	3.07	9.23	7.87
Dividends declared per share	$ 0.50	$ 0.41	$ 1.32	$ 1.15

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Comprehensive income
Net income	$ 227,591	$ 198,719	$ 605,293	$ 511,294
Other comprehensive income, net of tax:
Foreign currency translation adjustments	46,733	(28,233)	68,085	59,442
Net unrealized investment gains	(93,574)	254,658	415,870	1,445,776
Defined benefit pension and postretirement plan adjustments	700	527	2,473	(1,176)
Total other comprehensive income, net of tax	(46,141)	226,952	486,428	1,504,042
Total comprehensive income	$ 181,450	$ 425,671	$ 1,091,721	$ 2,015,336

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities:
Net income	$ 605,293	$ 511,294
Change in operating assets and liabilities:
Accrued investment income	(63,321)	(58,863)
Premiums receivable and other reinsurance balances	(421,027)	(3,619)
Deferred policy acquisition costs	67,471	(15,059)
Reinsurance ceded receivable balances	(120,013)	(77,741)
Future policy benefits, other policy claims and benefits, and other reinsurance balances	982,164	479,606
Deferred income taxes	236,185	165,988
Other assets and other liabilities, net	78,848	29,343
Amortization of net investment premiums, discounts and other	(95,227)	(55,967)
Depreciation, Depletion and Amortization	21,384	19,489
Investment related (gains) losses, net	(139,471)	(84,002)
Other, net	(47,787)	109,403
Net cash provided by operating activities	1,104,499	1,019,872
Cash Flows from Investing Activities:
Sales of fixed maturity securities available-for-sale	6,364,236	3,649,187
Maturities of fixed maturity securities available-for-sale	385,993	349,836
Proceeds from Sale of Available-for-sale Securities, Equity	192,821	331,978
Payments to Acquire Available-for-sale Securities, Debt	7,450,749	5,938,302
Payments to Acquire Available-for-sale Securities, Equity	(60,790)	(523,499)
Payments to Acquire Mortgage Notes Receivable	(751,702)	(857,445)
Proceeds from Sale and Collection of Mortgage Notes Receivable	208,052	377,671
Proceeds from Collection of Policy Loans	93,286	59,518
Payments for (Proceeds from) Policy Loans	5,830	5,685
Increase (Decrease) in Funds Held under Reinsurance Agreements	12,597	31,222
Payments to Acquire Property, Plant, and Equipment	(33,242)	0
Change in short-term investments	65,664	418,625
Change in other invested assets	(51,476)	(78,068)
Net cash used in investing activities	(1,056,334)	(2,247,406)
Cash Flows from Financing Activities:
Dividends to stockholders	(85,086)	(74,034)
Proceeds from (Repayments of) Secured Debt	(56,637)	(60,971)
Proceeds from Issuance of Long-term Debt	0	799,984
Payments of Debt Issuance Costs	0	(9,026)
Repayments of Long-term Debt	(301,927)	(1,850)
Purchases of treasury stock	(41,360)	(121,896)
Exercise of stock options, net	4,450	11,752
Change in cash collateral for derivative positions and other arrangements	(46,206)	24,749
Deposits on universal life and other investment type policies and contracts	1,007,563	874,708
Withdrawals on universal life and other investment type policies and contracts	(568,789)	(386,900)
Net cash provided by financing activities	(87,992)	1,056,516
Effect of exchange rate changes on cash	43,699	25,436
Change in cash and cash equivalents	3,872	(145,582)
Cash and cash equivalents, beginning of period	1,200,718	1,525,275
Cash and cash equivalents, end of period	1,204,590	1,379,693
Supplemental disclosures of cash flow information:
Interest Paid, Net	129,136	114,043
Income Taxes Paid, Net	27,385	47,312
Transfer to Investments	$ 2,247,136	$ 3,621

Business and Basis of Presentat

Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Business and Basis of Presentation Reinsurance Group of America, Incorporated (“RGA”) is an insurance holding company that was formed on December 31, 1992. The accompanying unaudited condensed consolidated financial statements of RGA and its subsidiaries (collectively, the “Company”) have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, these condensed consolidated financial statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments, including normal recurring adjustments necessary for a fair presentation have been included. Results for the nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 . These unaudited condensed consolidated financial statements include the accounts of RGA and its subsidiaries, and all intercompany accounts and transactions have been eliminated. These condensed consolidated statements should be read in conjunction with the Company’s 2016 Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on February 28, 2017 (the “2016 Annual Report”).

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table sets forth the computation of basic and diluted earnings per share on net income (in thousands, except per share information): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Earnings: Net income (numerator for basic and diluted calculations) $ 227,591 $ 198,719 $ 605,293 $ 511,294 Shares: Weighted average outstanding shares (denominator for basic calculation) 64,488 64,146 64,430 64,281 Equivalent shares from outstanding stock options 1,165 669 1,174 663 Denominator for diluted calculation 65,653 64,815 65,604 64,944 Earnings per share: Basic $ 3.53 $ 3.10 $ 9.39 $ 7.95 Diluted $ 3.47 $ 3.07 $ 9.23 $ 7.87 The calculation of common equivalent shares does not include the impact of options having a strike or conversion price that exceeds the average stock price for the earnings period, as the result would be antidilutive. The calculation of common equivalent shares also excludes the impact of outstanding performance contingent shares, as the conditions necessary for their issuance have not been satisfied as of the end of the reporting period. For the three months ended September 30, 2017 , 0.1 million stock options and approximately 0.3 million performance contingent shares were excluded from the calculation. For the three months ended September 30, 2016 , no stock options and approximately 0.7 million performance contingent shares were excluded from the calculation. Year-to-date amounts for equivalent shares from outstanding stock options and performance contingent shares are the weighted average of the individual quarterly amounts.

Equity

Equity	9 Months Ended
	Sep. 30, 2017
Stockholders' Equity Note [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	Equity Common Stock The changes in number of common stock shares, issued, held in treasury and outstanding are as follows for the periods indicated: Issued Held In Treasury Outstanding Balance, December 31, 2016 79,137,758 14,835,256 64,302,502 Common stock acquired — 208,680 (208,680 ) Stock-based compensation (1) — (274,449 ) 274,449 Balance, September 30, 2017 79,137,758 14,769,487 64,368,271 Issued Held In Treasury Outstanding Balance, December 31, 2015 79,137,758 13,933,232 65,204,526 Common stock acquired — 1,356,892 (1,356,892 ) Stock-based compensation (1) — (358,639 ) 358,639 Balance, September 30, 2016 79,137,758 14,931,485 64,206,273 (1) Represents net shares issued from treasury pursuant to the Company’s equity-based compensation programs. Common Stock Held in Treasury Common stock held in treasury is accounted for at average cost. Gains resulting from the reissuance of common stock held in treasury are credited to additional paid-in capital. Losses resulting from the reissuance of common stock held in treasury are charged first to additional paid-in capital to the extent the Company has previously recorded gains on treasury share transactions, then to retained earnings. On January 26, 2017, RGA’s board of directors authorized a share repurchase program for up to $400.0 million of RGA’s outstanding common stock. The authorization was effective immediately and does not have an expiration date. In connection with this new authorization, the board of directors terminated the stock repurchase authority granted in 2016. During the first nine months of 2017, RGA repurchased 0.2 million shares of common stock under this program for $26.9 million . Accumulated Other Comprehensive Income (Loss) The balance of and changes in each component of accumulated other comprehensive income (loss) (“AOCI”) for the nine months ended September 30, 2017 and 2016 are as follows (dollars in thousands): Accumulated Currency Translation Adjustments Unrealized Appreciation (Depreciation) of Investments (1) Pension and Postretirement Benefits Total Balance, December 31, 2016 $ (172,541 ) $ 1,355,033 $ (43,163 ) $ 1,139,329 Other comprehensive income (loss) before reclassifications 23,117 671,564 (191 ) 694,490 Amounts reclassified to (from) AOCI — (51,407 ) 4,006 (47,401 ) Deferred income tax benefit (expense) 44,968 (204,287 ) (1,342 ) (160,661 ) Balance, September 30, 2017 $ (104,456 ) $ 1,770,903 $ (40,690 ) $ 1,625,757 Accumulated Currency Translation Adjustments Unrealized Appreciation (Depreciation) of Investments (1) Pension and Postretirement Benefits Total Balance, December 31, 2015 $ (181,151 ) $ 935,697 $ (46,262 ) $ 708,284 Other comprehensive income (loss) before reclassifications 68,271 2,191,823 (6,079 ) 2,254,015 Amounts reclassified to (from) AOCI — (109,145 ) 4,253 (104,892 ) Deferred income tax benefit (expense) (8,829 ) (636,902 ) 650 (645,081 ) Balance, September 30, 2016 $ (121,709 ) $ 2,381,473 $ (47,438 ) $ 2,212,326 (1) Includes cash flow hedges of $347 and $(2,496) as of September 30, 2017 and December 31, 2016 , respectively, and $(40,597) and $(29,397) as of September 30, 2016 and December 31, 2015 , respectively. See Note 5 - “Derivative Instruments” for additional information on cash flow hedges. The following table presents the amounts of AOCI reclassifications for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Amount Reclassified from AOCI Three months ended September 30, Nine months ended September 30, Details about AOCI Components 2017 2016 2017 2016 Affected Line Item in Statements of Income Net unrealized investment gains (losses): Net unrealized gains and losses on available-for-sale securities $ 10,515 $ 72,351 $ 39,032 $ 84,250 Investment related gains (losses), net Cash flow hedges - Currency/Interest rate 230 200 560 454 (1) Cash flow hedges - Forward bond purchase commitments 224 137 286 (120 ) (1) Deferred policy acquisition costs attributed to unrealized gains and losses 1,116 12,090 11,529 24,561 (2) Total 12,085 84,778 51,407 109,145 Provision for income taxes (3,991 ) (27,680 ) (16,015 ) (32,676 ) Net unrealized gains (losses), net of tax $ 8,094 $ 57,098 $ 35,392 $ 76,469 Amortization of defined benefit plan items: Prior service cost (credit) $ 590 $ 391 $ 732 $ 238 (3) Actuarial gains/(losses) (1,661 ) (1,177 ) (4,738 ) (4,491 ) (3) Total (1,071 ) (786 ) (4,006 ) (4,253 ) Provision for income taxes 375 276 1,402 1,489 Amortization of defined benefit plans, net of tax $ (696 ) $ (510 ) $ (2,604 ) $ (2,764 ) Total reclassifications for the period $ 7,398 $ 56,588 $ 32,788 $ 73,705 (1) See Note 5 - “Derivative Instruments” for additional information on cash flow hedges. (2) This AOCI component is included in the computation of the deferred policy acquisition cost. See Note 8 – “Deferred Policy Acquisition Costs” of the 2016 Annual Report for additional details. (3) This AOCI component is included in the computation of the net periodic pension cost. See Note 10 – “Employee Benefit Plans” for additional deta

Equity Based Compensation

Equity Based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Based Compensation	Equity Based Compensation Equity compensation expense was $17.1 million and $27.1 million in the first nine months of 2017 and 2016 , respectively. In the first quarter of 2017, the Company granted 0.2 million stock appreciation rights at $129.72 weighted average exercise price per share and 0.2 million performance contingent units to employees. Additionally, non-employee directors were granted a total of 7,696 shares of common stock. As of September 30, 2017 , 1.6 million share options at a weighted average strike price per share of $60.77 were vested and exercisable, with a remaining weighted average exercise period of 4.6 years. As of September 30, 2017 , the total compensation cost of non-vested awards not yet recognized in the condensed consolidated financial statements was $32.5 million . It is estimated that these costs will vest over a weighted average period of 1.2 years.

Investments

Investments	9 Months Ended
	Sep. 30, 2017
Investments [Abstract]
Investments	Investments Fixed Maturity and Equity Securities Available-for-Sale The following tables provide information relating to investments in fixed maturity and equity securities by sector as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate securities $ 21,418,741 $ 1,209,999 $ 92,910 $ 22,535,830 61.9 % $ — Canadian and Canadian provincial governments 2,850,982 1,142,635 2,432 3,991,185 11.0 — Residential mortgage-backed securities 1,645,379 42,202 8,276 1,679,305 4.6 — Asset-backed securities 1,680,918 18,713 5,063 1,694,568 4.7 275 Commercial mortgage-backed securities 1,293,296 25,471 5,445 1,313,322 3.6 — U.S. government and agencies 1,621,053 13,614 30,998 1,603,669 4.4 — State and political subdivisions 614,099 52,919 5,987 661,031 1.8 — Other foreign government, supranational and foreign government-sponsored enterprises 2,765,500 145,025 7,693 2,902,832 8.0 — Total fixed maturity securities $ 33,889,968 $ 2,650,578 $ 158,804 $ 36,381,742 100.0 % $ 275 Non-redeemable preferred stock $ 41,878 $ 312 $ 3,289 $ 38,901 34.4 % Other equity securities 74,514 633 1,117 74,030 65.6 Total equity securities $ 116,392 $ 945 $ 4,406 $ 112,931 100.0 % December 31, 2016: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate securities $ 18,924,711 $ 911,618 $ 217,245 $ 19,619,084 61.1 % $ — Canadian and Canadian provincial governments 2,561,605 1,085,982 3,541 3,644,046 11.4 — Residential mortgage-backed securities 1,258,039 33,917 13,380 1,278,576 4.0 (375 ) Asset-backed securities 1,443,822 9,350 23,828 1,429,344 4.5 275 Commercial mortgage-backed securities 1,342,440 28,973 7,759 1,363,654 4.2 — U.S. government and agencies 1,518,702 12,644 63,044 1,468,302 4.6 — State and political subdivisions 566,761 37,499 12,464 591,796 1.8 — Other foreign government, supranational and foreign government-sponsored enterprises 2,595,707 123,054 19,938 2,698,823 8.4 — Total fixed maturity securities $ 30,211,787 $ 2,243,037 $ 361,199 $ 32,093,625 100.0 % $ (100 ) Non-redeemable preferred stock $ 55,812 $ 1,648 $ 6,337 $ 51,123 18.6 % Other equity securities 229,767 1,792 7,321 224,238 81.4 Total equity securities $ 285,579 $ 3,440 $ 13,658 $ 275,361 100.0 % The Company enters into various collateral arrangements with counterparties that require both the pledging and acceptance of fixed maturity securities as collateral. Pledged fixed maturity securities are included in fixed maturity securities, available-for-sale in the condensed consolidated balance sheets. Fixed maturity securities received as collateral are held in separate custodial accounts and are not recorded on the Company’s condensed consolidated balance sheets. Subject to certain constraints, the Company is permitted by contract to sell or repledge collateral it receives; however, as of September 30, 2017 and December 31, 2016 , none of the collateral received had been sold or repledged. The Company also holds assets in trust to satisfy collateral requirements under certain third-party reinsurance treaties. The following table includes fixed maturity securities pledged and received as collateral and assets in trust held to satisfy collateral requirements under derivative transactions and certain third-party reinsurance treaties as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities pledged as collateral $ 68,841 $ 72,365 $ 207,066 $ 210,676 Fixed maturity securities received as collateral n/a 461,237 n/a 300,925 Assets in trust held to satisfy collateral requirements 14,598,404 15,598,457 12,135,258 12,874,370 The Company monitors its concentrations of financial instruments on an ongoing basis and mitigates credit risk by maintaining a diversified investment portfolio which limits exposure to any one issuer. The Company’s exposure to concentrations of credit risk from single issuers greater than 10% of the Company’s stockholders’ equity included securities of the U.S. government and its agencies as well as the securities disclosed below as of September 30, 2017 and December 31, 2016 (dollars in thousands). September 30, 2017 December 31, 2016 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities guaranteed or issued by: Canadian province of Quebec $ 1,115,505 $ 1,766,749 $ 1,004,261 $ 1,612,957 Canadian province of Ontario 932,872 1,231,201 832,764 1,126,433 The amortized cost and estimated fair value of fixed maturity securities classified as available-for-sale at September 30, 2017 are shown by contractual maturity in the table below (dollars in thousands). Actual maturities can differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Asset and mortgage-backed securities are shown separately in the table below, as they are not due at a single maturity date. Amortized Cost Estimated Fair Value Available-for-sale: Due in one year or less $ 910,821 $ 915,586 Due after one year through five years 7,339,134 7,618,692 Due after five years through ten years 9,581,912 10,090,704 Due after ten years 11,438,508 13,069,565 Asset and mortgage-backed securities 4,619,593 4,687,195 Total $ 33,889,968 $ 36,381,742 Corporate Fixed Maturity Securities The tables below show the major industry types of the Company’s corporate fixed maturity holdings as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017: Estimated Amortized Cost Fair Value % of Total Finance $ 7,797,576 $ 8,146,891 36.2 % Industrial 11,323,024 11,914,845 52.8 Utility 2,298,141 2,474,094 11.0 Total $ 21,418,741 $ 22,535,830 100.0 % December 31, 2016: Estimated Amortized Cost Fair Value % of Total Finance $ 6,725,199 $ 6,888,968 35.2 % Industrial 10,228,813 10,639,613 54.2 Utility 1,970,699 2,090,503 10.6 Total $ 18,924,711 $ 19,619,084 100.0 % Other-Than-Temporary Impairments - Fixed Maturity and Equity Securities As discussed in Note 2 – “Summary of Significant Accounting Policies” of the 2016 Annual Report, a portion of certain other-than-temporary impairment (“OTTI”) losses on fixed maturity securities is recognized in AOCI. For these securities, the net amount recognized in the condensed consolidated statements of income (“credit loss impairments”) represents the difference between the amortized cost of the security and the net present value of its projected future cash flows discounted at the effective interest rate implicit in the debt security prior to impairment. Any remaining difference between the fair value and amortized cost is recognized in AOCI. The following table sets forth the amount of pre-tax credit loss impairments on fixed maturity securities held by the Company as of the dates indicated, for which a portion of the OTTI loss was recognized in AOCI, and the corresponding changes in such amounts (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Balance, beginning of period $ 3,677 $ 6,974 $ 6,013 $ 7,284 Credit loss OTTI previously recognized on securities which matured, paid down, prepaid or were sold during the period — — (2,336 ) (310 ) Balance, end of period $ 3,677 $ 6,974 $ 3,677 $ 6,974 Unrealized Losses for Fixed Maturity and Equity Securities Available-for-Sale The following table presents the total gross unrealized losses for the 1,165 and 1,535 fixed maturity and equity securities as of September 30, 2017 and December 31, 2016 , respectively, where the estimated fair value had declined and remained below amortized cost by the indicated amount (dollars in thousands): September 30, 2017 December 31, 2016 Gross Unrealized Losses % of Total Gross Unrealized Losses % of Total Less than 20% $ 140,313 86.0 % $ 337,831 90.1 % 20% or more for less than six months 3,407 2.1 19,438 5.2 20% or more for six months or greater 19,490 11.9 17,588 4.7 Total $ 163,210 100.0 % $ 374,857 100.0 % The Company’s determination of whether a decline in value is other-than-temporary includes analysis of the underlying credit and the extent and duration of a decline in value. The Company’s credit analysis of an investment includes determining whether the issuer is current on its contractual payments, evaluating whether it is probable that the Company will be able to collect all amounts due according to the contractual terms of the security and analyzing the overall ability of the Company to recover the amortized cost of the investment. In the Company’s impairment review process, the duration and severity of an unrealized loss position for equity securities are given greater weight and consideration given the lack of contractual cash flows or deferability features. The following tables present the estimated fair values and gross unrealized losses, including other-than-temporary impairment losses reported in AOCI, for 1,165 and 1,535 fixed maturity and equity securities that have estimated fair values below amortized cost as of September 30, 2017 and December 31, 2016 , respectively (dollars in thousands). These investments are presented by class and grade of security, as well as the length of time the related fair value has remained below amortized cost. Less than 12 months 12 months or greater Total Gross Gross Gross September 30, 2017: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate securities $ 2,035,856 $ 15,923 $ 1,213,026 $ 49,422 $ 3,248,882 $ 65,345 Canadian and Canadian provincial governments 97,100 1,320 46,663 1,112 143,763 2,432 Residential mortgage-backed securities 507,372 5,084 154,469 3,189 661,841 8,273 Asset-backed securities 516,613 2,318 133,848 2,213 650,461 4,531 Commercial mortgage-backed securities 293,834 3,224 61,707 2,221 355,541 5,445 U.S. government and agencies 1,302,732 29,712 56,595 1,286 1,359,327 30,998 State and political subdivisions 53,977 743 62,530 5,156 116,507 5,899 Other foreign government, supranational and foreign government-sponsored enterprises 327,813 2,529 104,333 4,865 432,146 7,394 Total investment grade securities 5,135,297 60,853 1,833,171 69,464 6,968,468 130,317 Below investment grade securities: Corporate securities 170,023 3,780 95,089 23,785 265,112 27,565 Residential mortgage-backed securities — — 93 3 93 3 Asset-backed securities — — 5,611 532 5,611 532 State and political subdivisions 919 88 — — 919 88 Other foreign government, supranational and foreign government-sponsored enterprises 11,219 77 15,667 222 26,886 299 Total below investment grade securities 182,161 3,945 116,460 24,542 298,621 28,487 Total fixed maturity securities $ 5,317,458 $ 64,798 $ 1,949,631 $ 94,006 $ 7,267,089 $ 158,804 Non-redeemable preferred stock $ 6,712 $ 345 $ 25,983 $ 2,944 $ 32,695 $ 3,289 Other equity securities 6,446 396 58,206 721 64,652 1,117 Total equity securities $ 13,158 $ 741 $ 84,189 $ 3,665 $ 97,347 $ 4,406 Less than 12 months 12 months or greater Total Gross Gross Gross December 31, 2016: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate securities $ 4,661,706 $ 124,444 $ 549,273 $ 43,282 $ 5,210,979 $ 167,726 Canadian and Canadian provincial governments 101,578 3,541 — — 101,578 3,541 Residential mortgage-backed securities 490,473 9,733 112,216 3,635 602,689 13,368 Asset-backed securities 563,259 12,010 257,166 9,653 820,425 21,663 Commercial mortgage-backed securities 368,465 6,858 10,853 166 379,318 7,024 U.S. government and agencies 1,056,101 63,044 — — 1,056,101 63,044 State and political subdivisions 187,194 9,396 13,635 3,068 200,829 12,464 Other foreign government, supranational and foreign government-sponsored enterprises 524,236 13,372 51,097 2,981 575,333 16,353 Total investment grade securities 7,953,012 242,398 994,240 62,785 8,947,252 305,183 Below investment grade securities: Corporate securities 330,757 7,914 163,152 41,605 493,909 49,519 Residential mortgage-backed securities — — 412 12 412 12 Asset-backed securities 5,904 700 12,581 1,465 18,485 2,165 Commercial mortgage-backed securities 5,815 735 — — 5,815 735 Other foreign government, supranational and foreign government-sponsored enterprises 32,355 1,258 39,763 2,327 72,118 3,585 Total below investment grade securities 374,831 10,607 215,908 45,409 590,739 56,016 Total fixed maturity securities $ 8,327,843 $ 253,005 $ 1,210,148 $ 108,194 $ 9,537,991 $ 361,199 Non-redeemable preferred stock $ 10,831 $ 831 $ 21,879 $ 5,506 $ 32,710 $ 6,337 Other equity securities 202,068 7,020 6,751 301 208,819 7,321 Total equity securities $ 212,899 $ 7,851 $ 28,630 $ 5,807 $ 241,529 $ 13,658 The Company has no intention to sell, nor does it expect to be required to sell, the securities outlined in the table above, as of the dates indicated. However, unforeseen facts and circumstances may cause the Company to sell fixed maturity and equity securities in the ordinary course of managing its portfolio to meet certain diversification, credit quality and liquidity guidelines. Unrealized losses on below investment grade securities as of September 30, 2017 are primarily related to high-yield corporate securities. Changes in unrealized losses are primarily being driven by changes in credit spreads and interest rates. Investment Income, Net of Related Expenses Major categories of investment income, net of related expenses, consist of the following (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Fixed maturity securities available-for-sale $ 359,157 $ 325,089 $ 1,039,392 $ 961,096 Mortgage loans on real estate 50,040 39,802 138,829 121,494 Policy loans 15,404 15,391 45,870 47,897 Funds withheld at interest 102,144 104,609 327,089 273,482 Short-term investments and cash and cash equivalents 1,977 1,752 5,266 6,265 Other invested assets 47,595 21,138 90,488 57,896 Investment income 576,317 507,781 1,646,934 1,468,130 Investment expense (19,399 ) (18,054 ) (57,114 ) (53,471 ) Investment income, net of related expenses $ 556,918 $ 489,727 $ 1,589,820 $ 1,414,659 Investment Related Gains (Losses), Net Investment related gains (losses), net consist of the following (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Fixed maturity and equity securities available for sale: Other-than-temporary impairment losses on fixed maturity securities recognized in earnings $ (390 ) $ — $ (20,980 ) $ (34,663 ) Impairment losses on equity securities (889 ) — (889 ) — Gain on investment activity 19,522 46,346 91,635 127,153 Loss on investment activity (7,678 ) (9,054 ) (30,712 ) (43,397 ) Other impairment losses and change in mortgage loan provision (2,446 ) (262 ) (9,220 ) (2,111 ) Derivatives and other, net 14,534 49,594 109,637 37,020 Total investment related gains (losses), net $ 22,653 $ 86,624 $ 139,471 $ 84,002 The fixed maturity impairments for the three and nine months ended September 30, 2017 and 2016 were largely related to high-yield and emerging market corporate securities. The equity impairments for the three and nine months ended September 30, 2017 were related to an equity position received as part of a debt restructuring. The other impairment losses and change in mortgage loan provision for the three and nine months ended September 30, 2017 and 2016 were primarily due to impairments on limited partnerships. The fluctuations in investment related gains (losses) for derivatives and other for the three and nine months ended September 30, 2017 , compared to the same periods in 2016 , are primarily due to changes in the fair value of embedded derivatives and interest rate swaps. During the three months ended September 30, 2017 and 2016 , the Company sold fixed maturity and equity securities with fair values of $484.7 million and $317.3 million at losses of $7.7 million and $9.1 million , respectively. During the nine months ended September 30, 2017 and 2016 , the Company sold fixed maturity and equity securities with fair values of $1,771.4 million and $903.1 million at losses of $30.7 million and $43.4 million , respectively. The Company generally does not buy and sell securities on a short-term basis. Securities Borrowing, Lending and Other The Company participates in securities borrowing programs whereby securities, which are not reflected on the Company’s condensed consolidated balance sheets, are borrowed from third parties. The borrowed securities are used to provide collateral under affiliated reinsurance transactions. The Company is required to maintain a minimum of 100% of the fair value, or par value, under certain programs, of the borrowed securities as collateral. The collateral consists of rights to reinsurance treaty cash flows. If cash flows from the reinsurance treaties are insufficient to maintain the minimum collateral requirement, the Company may substitute cash or securities to meet the requirement. No cash or securities have been pledged by the Company for this purpose. The Company also participates in a securities lending program whereby securities, reflected as investments on the Company’s condensed consolidated balance sheets, are loaned to a third party. The Company receives securities as collateral, in an amount equal to a minimum of 105% of the fair value of the securities lent. The securities received as collateral are not reflected on the Company’s condensed consolidated balance sheets. The Company also participates in repurchase/reverse repurchase programs in which securities, reflected as investments on the Company’s condensed consolidated balance sheets, are pledged to third parties. In return, the Company receives securities from the third parties with an estimated fair value equal to a minimum of 100% of the securities pledged. The securities received are not reflected on the Company’s condensed consolidated balance sheets. The Company also participates in a repurchase program in which securities, reflected as investments on the Company’s condensed consolidated balance sheets, are pledged to a third party. In return, the Company receives cash from the third party, which is reflected as a payable to the third party and included in other liabilities on the condensed consolidated balance sheets. The Company is required to maintain a minimum collateral balance with a fair value of 102% of the cash received. The following table includes the amount of borrowed securities, securities lent and securities collateral received as part of the securities lending program and repurchased/reverse repurchased securities pledged and received as of September 30, 2017 and December 31, 2016 (dollars in thousands). September 30, 2017 December 31, 2016 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Borrowed securities $ 360,475 $ 379,101 $ 263,820 $ 279,186 Securities lending: Securities loaned 117,219 121,958 74,389 73,625 Securities received n/a 120,000 n/a 80,000 Repurchase program/reverse repurchase program: Securities pledged 491,824 512,613 476,531 499,891 Securities received n/a 522,354 n/a 515,200 The Company also held cash collateral for securities lending and the repurchase program/reverse repurchase programs of $38.5 million and $28.8 million at September 30, 2017 and December 31, 2016 , respectively. The following table presents information on the Company’s securities lending and repurchase transactions as of September 30, 2017 and December 31, 2016 (dollars in thousands). Collateral associated with certain borrowed securities is not included within the table, as the collateral pledged to each counterparty is the right to reinsurance treaty cash flows. September 30, 2017 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Securities lending transactions: Corporate securities $ — $ — $ — $ 121,958 $ 121,958 Total — — — 121,958 121,958 Repurchase transactions: Corporate securities — 1,472 5,402 175,258 182,132 Residential mortgage-backed securities — — — 87,418 87,418 U.S. government and agencies — — 23,206 196,040 219,246 Foreign government — — — 21,370 21,370 Other 2,447 — — — 2,447 Total 2,447 1,472 28,608 480,086 512,613 Total transactions $ 2,447 $ 1,472 $ 28,608 $ 602,044 $ 634,571 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 680,850 Amounts related to agreements not included in offsetting disclosure $ 46,279 December 31, 2016 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Securities lending transactions: Corporate securities $ — $ — $ 4,017 $ 69,608 $ 73,625 Total $ — $ — $ 4,017 $ 69,608 $ 73,625 Repurchase transactions: Corporate securities $ — $ — $ 3,220 $ 166,979 $ 170,199 Residential mortgage-backed securities — — — 92,546 92,546 U.S. government and agencies — — — 216,000 216,000 Foreign government — — — 19,900 19,900 Other 1,246 — — — 1,246 Total 1,246 — 3,220 495,425 499,891 Total borrowings $ 1,246 $ — $ 7,237 $ 565,033 $ 573,516 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 624,032 Amounts related to agreements not included in offsetting disclosure $ 50,516 The Company has elected to offset amounts recognized as receivables and payables resulting from the repurchase/reverse repurchase programs. After the effect of offsetting, the net amount presented on the condensed consolidated balance sheets was a liability of $7.9 million and $5.5 million of September 30, 2017 and December 31, 2016 , respectively. As of September 30, 2017 and December 31, 2016 , the Company recognized payables resulting from cash received as collateral associated with a repurchase agreement as discussed above. Amounts owed to and due from the counterparties may be settled in cash or offset, in accordance with the agreements. Mortgage Loans on Real Estate Mortgage loans represented approximately 8.7% and 8.4% of the Company’s total investments as of September 30, 2017 and December 31, 2016 . The Company makes mortgage loans on income producing properties that are geographically diversified throughout the U.S. with the largest concentration being in the state of California, which represented 21.2% and 22.1% of mortgage loans on real estate as of September 30, 2017 and December 31, 2016 , respectively. The recorded investment in mortgage loans on real estate presented below is gross of unamortized deferred loan origination fees and expenses, and valuation allowances. The distribution of mortgage loans by property type is as follows as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Property type: Carrying Value % of Total Carrying Value % of Total Office building $ 1,426,673 32.9 % $ 1,270,113 33.6 % Retail 1,316,463 30.4 1,179,936 31.2 Industrial 891,051 20.6 713,461 18.8 Apartment 508,367 11.7 447,088 11.8 Other commercial 191,443 4.4 172,609 4.6 Recorded investment 4,333,997 100.0 % $ 3,783,207 100.0 % Unamortized balance of loan origination fees and expenses (2,531 ) — Valuation allowances (9,137 ) (7,685 ) Total mortgage loans on real estate $ 4,322,329 $ 3,775,522 The maturities of the mortgage loans as of September 30, 2017 and December 31, 2016 are as follows (dollars in thousands): September 30, 2017 December 31, 2016 Recorded Investment % of Total Recorded Investment % of Total Due within five years $ 1,086,700 25.1 % $ 822,073 21.7 % Due after five years through ten years 2,334,113 53.8 2,099,559 55.5 Due after ten years 913,184 21.1 861,575 22.8 Total $ 4,333,997 100.0 % $ 3,783,207 100.0 % The following tables set forth certain key credit quality indicators of the Company’s recorded investment in mortgage loans as of September 30, 2017 and December 31, 2016 (dollars in thousands): Recorded Investment Debt Service Ratios >1.20x 1.00x - 1.20x <1.00x Total % of Total September 30, 2017: Loan-to-Value Ratio 0% - 59.99% $ 2,060,277 $ 51,162 $ 4,698 $ 2,116,137 48.8 % 60% - 69.99% 1,515,469 86,613 44,358 1,646,440 38.0 70% - 79.99% 424,195 32,664 19,850 476,709 11.0 Greater than 80% 51,348 19,951 23,412 94,711 2.2 Total $ 4,051,289 $ 190,390 $ 92,318 $ 4,333,997 100.0 % Recorded Investment Debt Service Ratios >1.20x 1.00x - 1.20x <1.00x Total % of Total December 31, 2016: Loan-to-Value Ratio 0% - 59.99% $ 1,859,640 $ 64,749 $ 1,366 $ 1,925,755 50.8 % 60% - 69.99% 1,257,788 34,678 — 1,292,466 34.2 70% - 79.99% 370,092 20,869 24,369 415,330 11.0 Greater than 80% 114,297 — 35,359 149,656 4.0 Total $ 3,601,817 $ 120,296 $ 61,094 $ 3,783,207 100.0 % None of the payments due to the Company on its recorded investment in mortgage loans were delinquent as of September 30, 2017 and December 31, 2016 . The following table presents the recorded investment in mortgage loans, by method of measuring impairment, and the related valuation allowances as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Mortgage loans: Individually measured for impairment $ 5,856 $ 2,216 Collectively measured for impairment 4,328,141 3,780,991 Recorded investment $ 4,333,997 $ 3,783,207 Valuation allowances: Individually measured for impairment $ — $ — Collectively measured for impairment 9,137 7,685 Total valuation allowances $ 9,137 $ 7,685 Information regarding the Company’s loan valuation allowances for mortgage loans for the three and nine months ended September 30, 2017 and 2016 is as follows (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Balance, beginning of period $ 8,156 $ 6,499 $ 7,685 $ 6,813 Provision (release) 977 247 1,444 (67 ) Translation adjustment 4 — 8 — Balance, end of period $ 9,137 $ 6,746 $ 9,137 $ 6,746 Information regarding the portion of the Company’s mortgage loans that were impaired as of September 30, 2017 and December 31, 2016 is as follows (dollars in thousands): Unpaid Principal Balance Recorded Investment Related Allowance Carrying Value September 30, 2017: Impaired mortgage loans with no valuation allowance recorded $ 6,427 $ 5,856 $ — $ 5,856 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 6,427 $ 5,856 $ — $ 5,856 December 31, 2016: Impaired mortgage loans with no valuation allowance recorded $ 2,758 $ 2,216 $ — $ 2,216 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 2,758 $ 2,216 $ — $ 2,216 The Company’s average investment in impaired mortgage loans and the related interest income are reflected in the table below for the periods indicated (dollars in thousands): Three months ended September 30, 2017 2016 Average (1) Interest Income Average Recorded Investment (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 3,967 $ 33 $ 6,953 $ 107 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 3,967 $ 33 $ 6,953 $ 107 Nine months ended September 30, 2017 2016 Average (1) Interest Income Average (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 3,062 $ 100 $ 4,687 $ 324 Impaired mortgage loans with valuation allowance recorded — — 5,459 — Total impaired mortgage loans $ 3,062 $ 100 $ 10,146 $ 324 (1) Average recorded investment represents the average loan balances as of the beginning of period and all subsequent quarterly end of period balances. The Company did not acquire any impaired mortgage loans during the nine months ended September 30, 2017 and 2016 . The Company had no mortgage loans that were on a nonaccrual status at September 30, 2017 and December 31, 2016 . Policy Loans Policy loans comprised approximately 2.7% and 3.2% of the Company’s total investments as of September 30, 2017 and December 31, 2016 , respectively, the majority of which are associated with one client. These policy loans present no credit risk because the amount of the loan cannot exceed the obligation due to the ceding company upon the death of the insured or surrender of the underlying policy. The provisions of the treaties in force and the underlying policies determine the policy loan interest rates. The Company earns a spread between the interest rate earned on policy loans and the interest rate credited to corresponding liabilities. Funds Withheld at Interest Funds withheld at interest comprised approximately 12.1% and 13.1% of the Company’s total investments as of September 30, 2017 and December 31, 2016 , respectively. Of the $6.0 billion funds withheld at interest balance, net of embedded derivatives, as of September 30, 2017 , $4.0 billion of the balance is associated with one client. For reinsurance agreements written on a modified coinsurance basis and certain agreements written on a coinsurance funds withheld basis, assets equal to the net statutory reserves are withheld and legally owned and managed by the ceding company and are reflected as funds withheld at interest on the Company’s condensed consolidated balance sheets. In the event of a ceding company’s insolvency, the Company would need to assert a claim on the assets supporting its reserve liabilities. However, the risk of loss to the Company is mitigated by its ability to offset amounts it owes the ceding company for claims or allowances against amounts owed to the Company from the ceding company. Other Invested Assets Other invested assets include equity securities, limited partnership interests, joint ventures (other than operating joint ventures), derivative contracts and fair value option (“FVO”) contractholder-directed unit-linked investments. Other invested assets also include Federal Home Loan Bank of Des Moines (“FHLB”) common stock, equity release mortgages and structured loans, all of which are included in other in the table below. The fair value option was elected for contractholder-directed investments supporting unit-linked variable annuity type liabilities which do not qualify for presentation and reporting as separate accounts. Other invested assets represented approximately 3.1% and 3.6% of the Company’s total investments as of September 30, 2017 and December 31, 2016 , respectively. Carrying values of these assets as of September 30, 2017 and December 31, 2016 are as follows (dollars in thousands): September 30, 2017 December 31, 2016 Equity securities $ 112,931 $ 275,361 Limited partnership interests and real estate joint ventures 761,739 687,522 Derivatives 133,405 229,108 FVO contractholder-directed unit-linked investments 210,660 190,120 Other 313,788 209,829 Total other invested assets $ 1,532,523 $ 1,591,940

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Derivatives, except for embedded derivatives and longevity and mortality swaps, are carried on the Company’s condensed consolidated balance sheets in other invested assets or other liabilities, at fair value. Longevity and mortality swaps are included on the condensed consolidated balance sheets in other assets or other liabilities, at fair value. Embedded derivative assets and liabilities on modified coinsurance or funds withheld arrangements are included on the condensed consolidated balance sheets with the host contract in funds withheld at interest, at fair value. Embedded derivative liabilities on indexed annuity and variable annuity products are included on the condensed consolidated balance sheets with the host contract in interest-sensitive contract liabilities, at fair value. The following table presents the notional amounts and gross fair value of derivative instruments prior to taking into account the netting effects of master netting agreements as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Notional Carrying Value/Fair Value Notional Carrying Value/Fair Value Amount Assets Liabilities Amount Assets Liabilities Derivatives not designated as hedging instruments: Interest rate swaps $ 946,726 $ 61,263 $ 1,825 $ 949,556 $ 78,405 $ 5,949 Financial futures 448,600 — — 475,968 — — Foreign currency forwards 6,000 (84 ) — 25,000 — 5,070 Consumer price index swaps 132,081 589 420 20,615 — 262 Credit default swaps 948,000 7,905 490 926,000 12,012 2,871 Equity options 541,532 20,006 — 525,894 33,459 — Longevity swaps 945,120 37,827 — 841,360 26,958 — Mortality swaps 50,000 — 1,683 50,000 — 2,462 Synthetic guaranteed investment contracts 9,119,434 — — 8,834,700 — — Embedded derivatives in: Modified coinsurance or funds withheld arrangements — 84,325 — — — 22,529 Indexed annuity products — — 821,821 — — 805,672 Variable annuity products — — 168,119 — — 184,636 Total non-hedging derivatives 13,137,493 211,831 994,358 12,649,093 150,834 1,029,451 Derivatives designated as hedging instruments: Interest rate swaps 435,000 — 22,133 435,000 27,901 31,223 Foreign currency swaps 796,489 71,032 13,876 928,505 104,359 734 Foreign currency forwards 331,135 1,418 10,203 — — — Total hedging derivatives 1,562,624 72,450 46,212 1,363,505 132,260 31,957 Total derivatives $ 14,700,117 $ 284,281 $ 1,040,570 $ 14,012,598 $ 283,094 $ 1,061,408 Netting Arrangements Certain of the Company’s derivatives are subject to enforceable master netting arrangements and reported as a net asset or liability in the condensed consolidated balance sheets. The Company nets all derivatives that are subject to such arrangements. The Company has elected to include all derivatives, except embedded derivatives, in the tables below, irrespective of whether they are subject to an enforceable master netting arrangement or a similar agreement. See Note 4 – “Investments” for information regarding the Company’s securities borrowing, lending, repurchase and repurchase/reverse repurchase programs. See “Embedded Derivatives” below for information regarding the Company’s bifurcated embedded derivatives. The following table provides information relating to the Company’s derivative instruments as of September 30, 2017 and December 31, 2016 (dollars in thousands): Gross Amounts Not Offset in the Balance Sheet Gross Amounts Recognized Gross Amounts Offset in the Balance Sheet Net Amounts Presented in the Balance Sheet Financial Instruments (1) Cash Collateral Pledged/ Received Net Amount September 30, 2017: Derivative assets $ 199,956 $ (28,724 ) $ 171,232 $ (17,782 ) $ (174,120 ) $ (20,670 ) Derivative liabilities 50,630 (28,724 ) 21,906 (58,360 ) (30,771 ) (67,225 ) December 31, 2016: Derivative assets $ 283,094 $ (27,028 ) $ 256,066 $ (16,913 ) $ (254,498 ) $ (15,345 ) Derivative liabilities 48,571 (27,028 ) 21,543 (95,863 ) (1,441 ) (75,761 ) (1) Includes initial margin posted to a central clearing partner. Accounting for Derivative Instruments and Hedging Activities The Company does not enter into derivative instruments for speculative purposes. As discussed below under “Non-qualifying Derivatives and Derivatives for Purposes Other Than Hedging,” the Company uses various derivative instruments for risk management purposes that either do not qualify or have not been qualified for hedge accounting treatment. As of September 30, 2017 and December 31, 2016 , the Company held interest rate swaps that were designated and qualified as cash flow hedges of interest rate risk, for variable rate liabilities and foreign currency assets, foreign currency swaps and foreign currency forwards that were designated and qualified as hedges of a portion of its net investment in its foreign operations, foreign currency swaps that were designated and qualified as fair value hedges of foreign currency risk, and derivative instruments that were not designated as hedging instruments. See Note 2 – “Summary of Significant Accounting Policies” of the Company’s 2016 Annual Report for a detailed discussion of the accounting treatment for derivative instruments, including embedded derivatives. Derivative instruments are carried at fair value and generally require an insignificant amount of cash at inception of the contracts. Fair Value Hedges The Company designates and reports certain foreign currency swaps to hedge the foreign currency fair value exposure of foreign currency denominated assets as fair value hedges when they meet the requirements of the general accounting principles for Derivatives and Hedging . The gain or loss on the hedged item attributable to a change in foreign currency and the offsetting gain or loss on the related foreign currency swaps as of September 30, 2017 and 2016, were (dollars in thousands): Type of Fair Value Hedge Hedged Item Gains (Losses) Recognized for Derivatives Gains (Losses) Recognized for Hedged Items Ineffectiveness Recognized in Investment Related Gains (Losses), net For the three months ended September 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 2,100 $ (2,100 ) $ — For the three months ended September 30, 2016: Foreign currency swaps Foreign-denominated fixed maturity securities $ 3,205 $ (3,205 ) $ — For the nine months ended September 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 9,541 $ (9,541 ) $ — For the nine months ended September 30, 2016: Foreign currency swaps Foreign-denominated fixed maturity securities $ 5,317 $ (5,317 ) $ — A regression analysis was used, both at inception of the hedge and on an ongoing basis, to determine whether each derivative used in a hedged transaction is highly effective in offsetting changes in the hedged item. For the foreign currency swaps, the change in fair value related to changes in the benchmark interest rate and credit spreads are excluded from the hedge effectiveness. For the three and nine months ended September 30, 2017 , $0.2 million and $0.8 million , respectively, of the change in the estimated fair value of derivatives, was excluded from hedge effectiveness. For the three and nine months ended September 30, 2016 , $1.6 million and $(5.4) million , respectively, of the change in the estimated fair value of derivatives, was excluded from hedge effectiveness. Cash Flow Hedges Certain derivative instruments are designated as cash flow hedges when they meet the requirements of the general accounting principles for Derivatives and Hedging. The Company designates and accounts for the following as cash flows: (i) certain interest rate swaps, in which the cash flows of liabilities are variable based on a benchmark rate; (ii) certain interest rate swaps, in which the cash flows of assets are denominated in different currencies, commonly referred to as cross-currency swaps; and (iii) forward bond purchase commitments. The following table presents the components of AOCI, before income tax, and the condensed consolidated income statement classification where the gain or loss is recognized related to cash flow hedges for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Three months ended September 30, 2017 2016 Balance beginning of period $ 7,690 $ (41,192 ) Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges (6,889 ) 932 Amounts reclassified to investment related (gains) losses, net (183 ) (116 ) Amounts reclassified to investment income (271 ) (221 ) Balance end of period $ 347 $ (40,597 ) Nine months ended September 30, 2017 2016 Balance beginning of period $ (2,496 ) $ (29,397 ) Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges 3,689 (10,866 ) Amounts reclassified to investment related (gains) losses, net (142 ) 53 Amounts reclassified to investment income (704 ) (387 ) Balance end of period $ 347 $ (40,597 ) As of September 30, 2017 , the before-tax deferred net gains (losses) on derivative instruments recorded in AOCI that are expected to be reclassified to earnings during the next twelve months are approximately $(0.4) million . This expectation is based on the anticipated interest payments on hedged investments in fixed maturity securities that will occur over the next twelve months, at which time the Company will recognize the deferred net gains (losses) as an adjustment to investment income over the term of the investment cash flows. The following table presents the effective portion of derivatives in cash flow hedging relationships on the condensed consolidated statements of income and the condensed consolidated statements of comprehensive income for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Effective Portion Derivative Type Gain (Loss) Deferred in OCI Gain (Loss) Reclassified into Income from OCI Investment Related Gains (Losses) Investment Income For the three months ended September 30, 2017: Interest rate $ (8,421 ) $ — $ — Currency/Interest rate 1,544 — 230 Forward bond purchase commitments (12 ) 183 41 Total $ (6,889 ) $ 183 $ 271 For the three months ended September 30, 2016: Interest rate $ (3,282 ) $ — $ — Currency/Interest rate 4,214 — 200 Forward bond purchase commitments — 116 21 Total $ 932 $ 116 $ 221 For the nine months ended September 30, 2017: Interest rate $ (6,205 ) $ — $ — Currency/Interest rate 9,894 — 560 Forward bond purchase commitments — 142 144 Total $ 3,689 $ 142 $ 704 For the nine months ended September 30, 2016: Interest rate $ (15,617 ) $ — $ — Currency/Interest rate 4,751 — 454 Forward bond purchase commitments — (53 ) (67 ) Total $ (10,866 ) $ (53 ) $ 387 All components of each derivative’s gain or loss were included in the assessment of hedge effectiveness. For the three and nine months ended September 30, 2017 and 2016 , the ineffective portion of derivatives reported as cash flow hedges was not material to the Company’s results of operations. Also, there were no material amounts reclassified into earnings relating to instances in which the Company discontinued cash flow hedge accounting because the forecasted transaction did not occur by the anticipated date or within the additional time period permitted by the authoritative guidance for the accounting for derivatives and hedging. Hedges of Net Investments in Foreign Operations The Company uses foreign currency swaps and foreign currency forwards to hedge a portion of its net investment in certain foreign operations against adverse movements in exchange rates. The following table illustrates the Company’s net investments in foreign operations (“NIFO”) hedges for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Derivative Gains (Losses) Deferred in AOCI For the three months ended September 30, For the nine months ended September 30, Type of NIFO Hedge (1) (2) 2017 2016 2017 2016 Foreign currency swaps $ (35,198 ) $ 8,341 $ (60,723 ) $ (23,151 ) Foreign currency forwards 4,627 — 8,785 — Total $ (30,571 ) $ 8,341 $ (51,938 ) $ (23,151 ) (1) There were no sales or substantial liquidations of net investments in foreign operations that would have required the reclassification of gains or losses from accumulated other comprehensive income (loss) into investment income during the periods presented. (2) There was no ineffectiveness recognized for the Company’s hedges of net investments in foreign operations. The cumulative foreign currency translation gain recorded in AOCI related to these hedges was $109.7 million and $161.6 million at September 30, 2017 and December 31, 2016 , respectively. If a hedged foreign operation was sold or substantially liquidated, the amounts in AOCI would be reclassified to the condensed consolidated statements of income. A pro rata portion would be reclassified upon partial sale of a hedged foreign operation. Non-qualifying Derivatives and Derivatives for Purposes Other Than Hedging The Company uses various other derivative instruments for risk management purposes that either do not qualify or have not been qualified for hedge accounting treatment. The gain or loss related to the change in fair value for these derivative instruments is recognized in investment related gains (losses), net in the condensed consolidated statements of income, except where otherwise noted. A summary of the effect of non-hedging derivatives, including embedded derivatives, on the Company’s condensed consolidated statements of income for the three and nine months ended September 30, 2017 and 2016 is as follows (dollars in thousands): Gain (Loss) for the three months ended September 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2017 2016 Interest rate swaps Investment related gains (losses), net $ 641 $ 4,122 Financial futures Investment related gains (losses), net (8,890 ) (11,677 ) Foreign currency forwards Investment related gains (losses), net 24 507 CPI swaps Investment related gains (losses), net 220 76 Credit default swaps Investment related gains (losses), net 4,137 6,672 Equity options Investment related gains (losses), net (8,295 ) (13,648 ) Longevity swaps Other revenues 3,334 8,921 Mortality swaps Other revenues (132 ) (400 ) Subtotal (8,961 ) (5,427 ) Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 23,044 49,078 Indexed annuity products Interest credited (13,133 ) (20,104 ) Variable annuity products Investment related gains (losses), net (6,205 ) 7,988 Total non-hedging derivatives $ (5,255 ) $ 31,535 Gain (Loss) for the nine months ended September 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2017 2016 Interest rate swaps Investment related gains (losses), net $ 12,318 $ 108,149 Financial futures Investment related gains (losses), net (28,107 ) (30,285 ) Foreign currency forwards Investment related gains (losses), net 577 6,584 CPI swaps Investment related gains (losses), net 211 (624 ) Credit default swaps Investment related gains (losses), net 15,374 13,536 Equity options Investment related gains (losses), net (34,757 ) (19,576 ) Longevity swaps Other revenues 7,180 11,402 Mortality swaps Other revenues (921 ) 222 Subtotal (28,125 ) 89,408 Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 106,854 33,795 Indexed annuity products Interest credited (35,490 ) (20,730 ) Variable annuity products Investment related gains (losses), net 16,518 (83,089 ) Total non-hedging derivatives $ 59,757 $ 19,384 Types of Derivatives Used by the Company Interest Rate Swaps Interest rate swaps are used by the Company primarily to reduce market risks from changes in interest rates, to alter interest rate exposure arising from mismatches between assets and liabilities (duration mismatches) and to manage the risk of cash flows of liabilities that are variable based on a benchmark rate. With an interest rate swap, the Company agrees with another party to exchange, at specified intervals, the difference between two rates, which can be either fixed-rate or floating-rate interest amounts, tied to an agreed-upon notional principal amount. These transactions are executed pursuant to master agreements that provide for a single net payment or individual gross payments at each due date. The Company utilizes interest rate swaps in cash flow and non-qualifying hedging relationships. Financial Futures Exchange-traded futures are used primarily to economically hedge liabilities embedded in certain variable annuity products. With exchange-traded futures transactions, the Company agrees to purchase or sell a specified number of contracts, the value of which is determined by the relevant indices, and to post variation margin on a daily basis in an amount equal to the difference between the daily estimated fair values of those contracts. The Company enters into exchange-traded futures with regulated futures commission merchants that are members of the exchange. Equity Options Equity index options are used by the Company primarily to hedge minimum guarantees embedded in certain variable annuity products. To hedge against adverse changes in equity indices volatility, the Company buys put options. The contracts are net settled in cash based on differentials in the indices at the time of exercise and the strike price. Equity warrants are also used by the Company to economically hedge the variability in anticipated cash flows for the acquisition of investment securities. Consumer Price Index Swaps Consumer price index (“CPI”) swaps are used by the Company primarily to economically hedge liabilities embedded in certain insurance products where value is directly affected by changes in a designated benchmark consumer price index. With a CPI swap transaction, the Company agrees with another party to exchange the actual amount of inflation realized over a specified period of time for a fixed amount of inflation determined at inception. These transactions are executed pursuant to master agreements that provide for a single net payment or individual gross payments to be made by the counterparty at each due date. Most of these swaps will require a single payment to be made by one counterparty at the maturity date of the swap. Foreign Currency Swaps Foreign currency swaps are used by the Company to reduce the risk from fluctuations in foreign currency exchange rates associated with its assets and liabilities denominated in foreign currencies. With a foreign currency swap transaction, the Company agrees with another party to exchange, at specified intervals, the difference between one currency and another at a forward exchange rate calculated by reference to an agreed upon principal amount. The principal amount of each currency is exchanged at the termination of the currency swap by each party. The Company uses foreign currency swaps in hedges of net investments in foreign operations and non-qualifying hedge relationships. Foreign Currency Forwards Foreign currency forwards are used by the Company to reduce the risk from fluctuations in foreign currency exchange rates associated with its assets and liabilities denominated in foreign currencies. With a foreign currency forward transaction, the Company agrees with another party to deliver a specified amount of an identified currency at a specified future date. The price is agreed upon at the time of the contract and payment for such a contract is made in a different currency at the specified future date. The Company uses foreign currency forwards in hedges of net investments in foreign operations and non-qualifying hedge relationships. Forward Bond Purchase Commitments Forward bond purchase commitments have been used by the Company to hedge against the variability in the anticipated cash flows required to purchase securities. With forward bond purchase commitments, the forward price is agreed upon at the time of the contract and payment for such contract is made at the future specified settlement date of the securities. Credit Default Swaps The Company sells protection under single name credit default swaps and credit default swap index tranches to diversify its credit risk exposure in certain portfolios and, in combination with purchasing securities, to replicate characteristics of similar investments based on the credit quality and term of the credit default swap. Credit default triggers for indexed reference entities and single name reference entities are defined in the contracts. The Company’s maximum exposure to credit loss equals the notional value for credit default swaps. In the event of default of a referencing entity, the Company is typically required to pay the protection holder the full notional value less a recovery amount determined at auction. The following table presents the estimated fair value, maximum amount of future payments and weighted average years to maturity of credit default swaps sold by the Company at September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Rating Agency Designation of Referenced Credit Obligations (1) Estimated Fair Value of Credit Default Swaps Maximum Amount of Future Payments under Credit Default Swaps (2) Weighted Average Years to Maturity (3) Estimated Fair Value of Credit Default Swaps Maximum Amount of Future Payments under Credit Default Swaps (2) Weighted Average Years to Maturity (3) AAA/AA+/AA/AA-/A+/A/A- Single name credit default swaps $ 2,975 $ 155,500 3.2 $ 1,726 $ 150,500 3.8 Subtotal 2,975 155,500 3.2 1,726 150,500 3.8 BBB+/BBB/BBB- Single name credit default swaps 4,209 368,200 3.2 1,426 347,200 3.7 Credit default swaps referencing indices 56 416,000 4.2 6,295 416,000 5.0 Subtotal 4,265 784,200 3.7 7,721 763,200 4.4 BB+/BB/BB- Single name credit default swaps 21 5,000 1.7 (477 ) 9,000 3.5 Subtotal 21 5,000 1.7 (477 ) 9,000 3.5 Total $ 7,261 $ 944,700 3.6 $ 8,970 $ 922,700 4.3 (1) The rating agency designations are based on ratings from Standard and Poor’s (“S&P”). (2) Assumes the value of the referenced credit obligations is zero. (3) The weighted average years to maturity of the credit default swaps is calculated based on weighted average notional amounts. The Company also purchases credit default swaps to reduce its risk against a drop in bond prices due to credit concerns of certain bond issuers. If a credit event, as defined by the contract, occurs, the Company is able to put the bond back to the counterparty at par. Longevity Swaps The Company enters into longevity swaps in the form of out-of-the-money options, which provide protection against changes in mortality improvement to retirement plans and insurers of such plans. With a longevity swap transaction, the Company agrees with another party to exchange a proportion of a notional value. The proportion is determined by the difference between a predefined benefit, and the realized benefit plus the future expected benefit, calculated by reference to a population index for a fixed premium. Mortality Swaps Mortality swaps are used by the Company to hedge risk from changes in mortality experience associated with its reinsurance of life insurance risk. The Company agrees with another party to exchange, at specified intervals, a proportion of a notional value determined by the difference between a predefined expected and realized claim amount on a designated index of reinsured lives, for a fixed percentage (premium) each term. Synthetic Guaranteed Investment Contracts The Company sells fee-based synthetic guaranteed investment contracts to retirement plans which include investment-only, stable value contracts. The assets are owned by the trustees of such plans, who invest the assets under the terms of investment guidelines to which the Company agrees. The contracts contain a guarantee of a minimum rate of return on participant balances supported by the underlying assets, and a guarantee of liquidity to meet certain participant-initiated plan cash flow requirements. These contracts are reported as derivatives and recorded at fair value. Embedded Derivatives The Company has certain embedded derivatives which are required to be separated from their host contracts and reported as derivatives. Host contracts include reinsurance treaties structured on a modified coinsurance (“modco”) or funds withheld basis. Additionally, the Company reinsures equity-indexed annuity and variable annuity contracts with benefits that are considered embedded derivatives, including guaranteed minimum withdrawal benefits, guaranteed minimum accumulation benefits, and guaranteed minimum income benefits. The changes in fair values of embedded derivatives on equity-indexed annuities described below relate to changes in the fair value associated with capital market and other related assumptions. The Company’s utilization of a credit valuation adjustment (“CVA”) did not have a material effect on the change in fair value of its embedded derivatives for the three and nine months ended September 30, 2017 and 2016 . The related gains (losses) and the effect on net income after amortization of deferred acquisition costs (“DAC”) and income taxes for the three and nine months ended September 30, 2017 and 2016 are reflected in the following table (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Embedded derivatives in modco or funds withheld arrangements included in investment related gains $ 23,044 $ 49,078 $ 106,854 $ 33,795 After the associated amortization of DAC and taxes, the related amounts included in net income 7,515 9,653 36,300 1,683 Embedded derivatives in variable annuity contracts included in investment related gains (6,205 ) 7,988 16,518 (83,089 ) After the associated amortization of DAC and taxes, the related amounts included in net income (1,074 ) 2,595 30,785 (63,415 ) Amounts related to embedded derivatives in equity-indexed annuities included in benefits and expenses (13,133 ) (20,104 ) (35,490 ) (20,730 ) After the associated amortization of DAC and taxes, the related amounts included in net income (9,737 ) (13,397 ) (38,059 ) (9,979 ) Credit Risk The Company manages its credit risk related to over-the-counter (“OTC”) derivatives by entering into transactions with creditworthy counterparties, maintaining collateral arrangements and through the use of master netting agreements that provide for a single net payment to be made by one counterparty to another at each due date and upon termination. The credit exposure of the Company’s OTC derivative transactions is represented by the contracts with a positive fair value (market value) at the reporting date. To reduce credit exposures, the Company seeks to (i) enter into OTC derivative transactions pursuant to master netting agreements that provide for a netting of payments and receipts with a single counterparty, and (ii) enter into agreements that allow the use of credit support annexes, which are bilateral rating-sensitive agreements that require collateral postings at established threshold levels. Certain of the Company’s OTC derivatives are cleared derivatives, which are bilateral transactions between the Company and a counterparty where the transactions are cleared through a clearinghouse, such that each derivative counterparty is only exposed to the default of the clearinghouse. These cleared transactions require initial and daily variation margin collateral postings and include certain interest rate swaps and credit default swaps entered into on or after June 10, 2013, related to guidelines implemented under the Dodd-Frank Wall Street Reform and Consumer Protection Act. Also, the Company enters into exchange-traded futures through regulated exchanges and these transactions are settled on a daily basis, thereby reducing credit risk exposure in the event of non-performance by counterparties to such financial instruments. The Company enters into various collateral arrangements, which require both the posting and accepting of collateral in connection with its derivative instruments. Collateral agreements contain attachment thresholds that may vary depending on the posting party’s ratings. Additionally, a decline in the Company’s or the counterparty’s credit ratings to specified levels could result in potential settlement of the derivative positions under the Company’s agreements with its counterparties. The Company also has exchange-traded futures, which require the maintenance of a margin account. As exchange-traded futures are affected through regulated exchanges, and positions are marked to market on a daily basis, the Company has minimal exposure to credit-related losses in the event of nonperformance by counterparties. The Company’s credit exposure related to derivative contracts is generally limited to the fair value at the reporting date plus or minus any collateral posted or held by the Company. The Company’s credit exposure to mortality swaps is minimal, as they are fully collateralized by a counterparty. Information regarding the Company’s credit exposure related to its over-the-counter derivative contracts, centrally cleared derivative contracts and margin account for exchange-traded futures, excluding mortality swaps, at September 30, 2017 and December 31, 2016 are reflected in the following table (dollars in thousands): September 30, 2017 December 31, 2016 Estimated fair value of derivatives in net asset position $ 151,009 $ 236,985 Cash provided as collateral (1) 30,771 1,441 Securities pledged to counterparties as collateral (2) 58,360 95,863 Cash pledged from counterparties as collateral (3) (174,120 ) (254,498 ) Securities pledged from counterparties as collateral (4) (17,782 ) (16,913 ) Initial margin for cleared derivatives (2) (58,360 ) (73,571 ) Net amount after application of master netting agreements and collateral $ (10,122 ) $ (10,693 ) Margin account related to exchange-traded futures (5) $ 7,832 $ 9,687 (1) Consists of receivable from counterparty, included in other assets. (2) Included in available-for-sale securities, primarily consists of U.S. Treasury and government agency securities. (3) Included in cash and cash equivalents, with obligation to return cash collateral recorded in other liabilities. (4) Consists of U.S. Treasury and government securities. (5) Included in other assets.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Disclosures	Fair Value of Assets and Liabilities Fair Value Measurement General accounting principles for Fair Value Measurements and Disclosures define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. These principles also establish a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value and describes three levels of inputs that may be used to measure fair value: Level 1 - Unadjusted quoted prices in active markets for identical assets or liabilities. The Company’s Level 1 assets and liabilities are traded in active exchange markets. Level 2 - Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or market standard valuation techniques and assumptions that use significant inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the related assets or liabilities. Prices are determined using valuation methodologies such as discounted cash flow models and other similar techniques that require management’s judgment or estimation in developing inputs that are consistent with those other market participants would use when pricing similar assets and liabilities. Additionally, the Company’s embedded derivatives, all of which are associated with reinsurance treaties and longevity and mortality swaps, are classified in Level 3 since their values include significant unobservable inputs. When inputs used to measure the fair value of an asset or liability fall within different levels of the hierarchy, the level within which the fair value measurement is categorized is based on the lowest level input that is significant to the fair value measurement in its entirety, except for fair value measurements using net asset value. For example, a Level 3 fair value measurement may include inputs that are observable (Levels 1 and 2) and unobservable (Level 3). Therefore, gains and losses for such assets and liabilities categorized within Level 3 may include changes in fair value that are attributable to both observable inputs (Levels 1 and 2) and unobservable inputs (Level 3). Assets and Liabilities by Hierarchy Level Assets and liabilities measured at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 are summarized below (dollars in thousands): September 30, 2017: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate securities $ 22,535,830 $ 615,433 $ 20,648,377 $ 1,272,020 Canadian and Canadian provincial governments 3,991,185 — 3,465,820 525,365 Residential mortgage-backed securities 1,679,305 — 1,561,310 117,995 Asset-backed securities 1,694,568 — 1,549,371 145,197 Commercial mortgage-backed securities 1,313,322 — 1,311,375 1,947 U.S. government and agencies 1,603,669 1,480,357 100,061 23,251 State and political subdivisions 661,031 — 619,519 41,512 Other foreign government supranational and foreign government-sponsored enterprises 2,902,832 319,147 2,578,057 5,628 Total fixed maturity securities – available-for-sale 36,381,742 2,414,937 31,833,890 2,132,915 Funds withheld at interest – embedded derivatives 84,325 — — 84,325 Cash equivalents 332,186 332,186 — — Short-term investments 56,454 — 53,095 3,359 Other invested assets: Non-redeemable preferred stock 38,901 38,901 — — Other equity securities 74,030 74,030 — — Derivatives: Interest rate swaps 46,258 — 46,258 — Foreign currency forwards 1,418 — 1,418 — CPI swaps 230 — 230 — Credit default swaps 6,903 — 6,903 — Equity options 9,700 — 9,700 — Foreign currency swaps 68,896 — 68,896 — FVO contractholder-directed unit-linked investments 210,660 209,136 1,524 — Total other invested assets 456,996 322,067 134,929 — Other assets - longevity swaps 37,827 — — 37,827 Total $ 37,349,530 $ 3,069,190 $ 32,021,914 $ 2,258,426 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 989,940 $ — $ — $ 989,940 Other liabilities: Derivatives: Interest rate swaps 8,953 — 8,953 — Foreign currency forwards 10,287 — 10,287 — CPI swaps 61 — 61 — Credit default swaps (512 ) — (512 ) — Equity options (10,306 ) — (10,306 ) — Foreign currency swaps 11,740 — 11,740 — Mortality swaps 1,683 — — 1,683 Total $ 1,011,846 $ — $ 20,223 $ 991,623 December 31, 2016: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate securities $ 19,619,084 $ 310,995 $ 18,035,836 $ 1,272,253 Canadian and Canadian provincial governments 3,644,046 — 3,168,081 475,965 Residential mortgage-backed securities 1,278,576 — 1,118,285 160,291 Asset-backed securities 1,429,344 — 1,210,064 219,280 Commercial mortgage-backed securities 1,363,654 — 1,342,509 21,145 U.S. government and agencies 1,468,302 1,345,755 98,059 24,488 State and political subdivisions 591,796 — 550,130 41,666 Other foreign government, supranational and foreign government-sponsored enterprises 2,698,823 276,729 2,409,225 12,869 Total fixed maturity securities – available-for-sale 32,093,625 1,933,479 27,932,189 2,227,957 Funds withheld at interest – embedded derivatives (22,529 ) — — (22,529 ) Cash equivalents 338,601 338,601 — — Short-term investments 44,241 8,276 32,619 3,346 Other invested assets: Non-redeemable preferred stock 51,123 38,317 12,806 — Other equity securities 224,238 224,238 — — Derivatives: Interest rate swaps 93,508 — 93,508 — Credit default swaps 9,136 — 9,136 — Equity options 26,070 — 26,070 — Foreign currency swaps 100,394 — 100,394 — FVO contractholder-directed unit-linked investments 190,120 188,891 1,229 — Other 11,036 11,036 — — Total other invested assets 705,625 462,482 243,143 — Other assets - longevity swaps 26,958 — — 26,958 Total $ 33,186,521 $ 2,742,838 $ 28,207,951 $ 2,235,732 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 990,308 $ — $ — $ 990,308 Other liabilities: Derivatives: Interest rate swaps 24,374 — 24,374 — Foreign currency forwards 5,070 — 5,070 — CPI swaps 262 — 262 — Credit default swaps (5 ) — (5 ) — Equity options (7,389 ) — (7,389 ) — Foreign currency swaps (3,231 ) — (3,231 ) — Mortality swaps 2,462 — — 2,462 Total $ 1,011,851 $ — $ 19,081 $ 992,770 The Company may utilize information from third parties, such as pricing services and brokers, to assist in determining the fair value for certain assets and liabilities; however, management is ultimately responsible for all fair values presented in the Company’s condensed consolidated financial statements. This includes responsibility for monitoring the fair value process, ensuring objective and reliable valuation practices and pricing of assets and liabilities, and approving changes to valuation methodologies and pricing sources. The selection of the valuation technique(s) to apply considers the definition of an exit price and the nature of the asset or liability being valued and significant expertise and judgment is required. The Company performs initial and ongoing analysis and review of the various techniques utilized in determining fair value to ensure that they are appropriate and consistently applied, and that the various assumptions are reasonable. The Company analyzes and reviews the information and prices received from third parties to ensure that the prices represent a reasonable estimate of the fair value and to monitor controls around pricing, which includes quantitative and qualitative analysis and is overseen by the Company’s investment and accounting personnel. Examples of procedures performed include, but are not limited to, review of pricing trends, comparison of a sample of executed prices of securities sold to the fair value estimates, comparison of fair value estimates to management’s knowledge of the current market, and ongoing confirmation that third party pricing services use, wherever possible, market-based parameters for valuation. In addition, the Company utilizes both internal and external cash flow models to analyze the reasonableness of fair values utilizing credit spread and other market assumptions, where appropriate. As a result of the analysis, if the Company determines there is a more appropriate fair value based upon the available market data, the price received from the third party is adjusted accordingly. The Company also determines if the inputs used in estimated fair values received from pricing services are observable by assessing whether these inputs can be corroborated by observable market data. For assets and liabilities reported at fair value, the Company utilizes, when available, fair values based on quoted prices in active markets that are regularly and readily obtainable. Generally, these are very liquid investments and the valuation does not require management judgment. When quoted prices in active markets are not available, fair value is based on market valuation techniques, market comparable pricing and the income approach. The use of different techniques, assumptions and inputs may have a material effect on the estimated fair values of the Company’s securities holdings. For the periods presented, the application of market standard valuation techniques applied to similar assets and liabilities has been consistent. The methods and assumptions the Company uses to estimate the fair value of assets and liabilities measured at fair value on a recurring basis are summarized below. Fixed Maturity Securities – The fair values of the Company’s publicly-traded fixed maturity securities are generally based on prices obtained from independent pricing services. Prices from pricing services are sourced from multiple vendors, and a vendor hierarchy is maintained by asset type based on historical pricing experience and vendor expertise. The Company generally receives prices from multiple pricing services for each security, but ultimately uses the price from the vendor that is highest in the hierarchy for the respective asset type. To validate reasonableness, prices are periodically reviewed as explained above. Consistent with the fair value hierarchy described above, securities with quotes from pricing services are generally reflected within Level 2, as they are primarily based on observable pricing for similar assets and/or other market observable inputs. If the pricing information received from third party pricing services is not reflective of market activity or other inputs observable in the market, the Company may challenge the price through a formal process with the pricing service. If the Company ultimately concludes that pricing information received from the independent pricing service is not reflective of fair value, non-binding broker quotes are used, if available. If the Company concludes that the values from both pricing services and brokers are not reflective of fair value, an internally developed valuation may be prepared; however, this occurs infrequently. Internally developed valuations or non-binding broker quotes are also used to determine fair value in circumstances where vendor pricing is not available. These valuations may use significant unobservable inputs, which reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset. Observable market data may not be available in certain circumstances, such as market illiquidity and credit events related to the security. Pricing service overrides, internally developed valuations and non-binding broker quotes are generally based on significant unobservable inputs and are reflected as Level 3 in the valuation hierarchy. The inputs used in the valuation of corporate and government securities include, but are not limited to standard market observable inputs which are derived from, or corroborated by, market observable data including market yield curve, duration, call provisions, observable prices and spreads for similar publicly traded or privately traded issues that incorporate the credit quality and industry sector of the issuer. For structured securities, valuation is based primarily on matrix pricing or other similar techniques using standard market inputs including spreads for actively traded securities, spreads off benchmark yields, expected prepayment speeds and volumes, current and forecasted loss severity, rating, weighted average coupon, weighted average maturity, average delinquency rates, geographic region, debt-service coverage ratios and issuance-specific information including, but not limited to: collateral type, payment terms of the underlying assets, payment priority within the tranche, structure of the security, deal performance and vintage of loans. When observable inputs are not available, the market standard valuation techniques for determining the estimated fair value of certain types of securities that trade infrequently, and therefore have little or no price transparency, rely on inputs that are significant to the estimated fair value that are not observable in the market or cannot be derived principally from or corroborated by observable market data. These unobservable inputs can be based in large part on management judgment or estimation, and cannot be supported by reference to market activity. Even though unobservable, these inputs are based on assumptions deemed appropriate given the circumstances and are believed to be consistent with what other market participants would use when pricing such securities. The fair values of private placement securities are primarily determined using a discounted cash flow model. In certain cases these models primarily use observable inputs with a discount rate based upon the average of spread surveys collected from private market intermediaries who are active in both primary and secondary transactions, taking into account, among other factors, the credit quality and industry sector of the issuer and the reduced liquidity associated with private placements. Generally, these securities have been reflected within Level 3. For certain private fixed maturities, the discounted cash flow model may also incorporate significant unobservable inputs, which reflect the Company’s own assumptions about the inputs market participants would use in pricing the security. To the extent management determines that such unobservable inputs are not significant to the price of a security, a Level 2 classification is made. Otherwise, a Level 3 classification is used. Embedded Derivatives – The fair value of embedded derivative liabilities, including those calculated by third parties, are monitored through the use of attribution reports to quantify the effect of underlying sources of fair value change, including capital market inputs based on policyholder account values, interest rates and short-term and long-term implied volatilities, from period to period. Actuarial assumptions are based on experience studies performed internally in combination with available industry information and are reviewed on a periodic basis, at least annually. For embedded derivative liabilities associated with the underlying products in reinsurance treaties, primarily equity-indexed and variable annuity treaties, the Company utilizes a discounted cash flow model, which includes an estimate of future equity option purchases and an adjustment for a CVA. The variable annuity embedded derivative calculations are performed by third parties based on methodology and input assumptions provided by the Company. To validate the reasonableness of the resulting fair value, the Company’s internal actuaries perform reviews and analytical procedures on the results. The capital market inputs to the model, such as equity indexes, short-term equity volatility and interest rates, are generally observable. The valuation also requires certain significant inputs, which are generally not observable and accordingly, the valuation is considered Level 3 in the fair value hierarchy, see “Level 3 Measurements and Transfers” below for a description. The fair value of embedded derivatives associated with funds withheld reinsurance treaties is determined based upon a total return swap technique with reference to the fair value of the investments held by the ceding company that support the Company’s funds withheld at interest asset with an adjustment for a CVA. The fair value of the underlying assets is generally based on market observable inputs using industry standard valuation techniques. The valuation also requires certain significant inputs, which are generally not observable and accordingly, the valuation is considered Level 3 in the fair value hierarchy, see “Level 3 Measurements and Transfers” below for a description. Credit Valuation Adjustment – The Company uses a structural default risk model to estimate a CVA. The input assumptions are a combination of externally derived and published values (default threshold and uncertainty), market inputs (interest rate, equity price per share, debt per share, equity price volatility) and insurance industry data (Loss Given Default), adjusted for market recoverability. Cash Equivalents and Short-Term Investments – Cash equivalents and short-term investments include money market instruments, commercial paper and other highly liquid debt instruments. Money market instruments are generally valued using unadjusted quoted prices in active markets that are accessible for identical assets and are primarily classified as Level 1. The fair value of certain other cash equivalents and short-term investments, such as floating rate notes and bonds with original maturities less than twelve months, are based upon other market observable data and are typically classified as Level 2. However, certain short-term investments may incorporate significant unobservable inputs resulting in a Level 3 classification. Various time deposits carried as cash equivalents or short-term investments are not measured at estimated fair value and therefore are excluded from the tables presented. Equity Securities – Equity securities consist principally of exchange-traded funds and preferred stock of publicly and privately traded companies. The fair values of publicly traded equity securities are primarily based on quoted market prices in active markets and are classified within Level 1 in the fair value hierarchy. The fair values of preferred equity securities, for which quoted market prices are not readily available, are based on prices obtained from independent pricing services and these securities are generally classified within Level 2 in the fair value hierarchy. Non-binding broker quotes for equity securities are generally based on significant unobservable inputs and are reflected as Level 3 in the fair value hierarchy. FVO Contractholder-Directed Unit-Linked Investments – FVO contractholder-directed investments supporting unit-linked variable annuity type liabilities primarily consist of exchange-traded funds and, to a lesser extent, fixed maturity securities and cash and cash equivalents. The fair values of the exchange-traded securities are primarily based on quoted market prices in active markets and are classified within Level 1 of the hierarchy. The fair value of the fixed maturity contractholder-directed securities is determined on a basis consistent with the methodologies described above for fixed maturity securities and are classified within Level 2 of the hierarchy. Derivative Assets and Derivative Liabilities – All of the derivative instruments utilized by the Company, except for longevity and mortality swaps, are classified within Level 2 on the fair value hierarchy. These derivatives are principally valued using an income approach. Valuations of interest rate contracts are based on present value techniques, which utilize significant inputs that may include the swap yield curve, London Interbank Offered Rate (“LIBOR”) basis curves, and repurchase rates. Valuations of foreign currency contracts, are based on present value techniques, which utilize significant inputs that may include the swap yield curve, LIBOR basis curves, currency spot rates, and cross currency basis curves. Valuations of credit contracts are based on present value techniques, which utilize significant inputs that may include the swap yield curve, credit curves, and recovery rates. Valuations of equity market contracts, are based on present value techniques, which utilize significant inputs that may include the swap yield curve, spot equity index levels, and dividend yield curves. Valuations of equity market contracts, option-based, are based on option pricing models, which utilize significant inputs that may include the swap yield curve, spot equity index levels, dividend yield curves, and equity volatility. The Company does not currently have derivatives, except for longevity and mortality swaps, included in Level 3 measurement. Longevity and Mortality Swaps – The Company utilizes a discounted cash flow model to estimate the fair value of longevity and mortality swaps. The fair value of these swaps includes an accrual for premiums payable and receivable. Some inputs to the valuation model are generally observable, such as interest rates and actual population mortality experience. The valuation also requires significant inputs that are generally not observable and, accordingly, the valuation is considered Level 3 in the fair value hierarchy. Level 3 Measurements and Transfers As of September 30, 2017 and December 31, 2016 , the Company classified approximately 5.9% and 6.9% , respectively, of its fixed maturity securities in the Level 3 category. These securities primarily consist of private placement corporate securities and bank loans as well as Canadian provincial strips with inactive trading markets. Additionally, the Company has included asset-backed securities with subprime exposure and mortgage-backed securities with below investment grade ratings in the Level 3 category due to market uncertainty associated with these securities and the Company’s utilization of unobservable information from third parties for the valuation of these securities. The significant unobservable inputs used in the fair value measurement of the Company’s corporate, sovereign, government-backed, and other political subdivision investments are probability of default, liquidity premium and subordination premium. Significant increases (decreases) in any of those inputs in isolation would result in a significantly lower (higher) fair value measurement. Generally, a change in the assumption used for the probability of default is accompanied by a directionally similar change in the assumptions used for the liquidity premium and subordination premium. For securities with a fair value derived using the market comparable pricing valuation technique, liquidity premium is the only significant unobservable input. The significant unobservable inputs used in the fair value measurement of the Company’s asset and mortgage-backed securities are prepayment rates, probability of default, liquidity premium and loss severity in the event of default. Significant increases (decreases) in any of those inputs in isolation would result in a significantly lower (higher) fair value measurement. Generally, a change in the assumption used for the probability of default is accompanied by a directionally similar change in the assumption used for the liquidity premium and loss severity and a directionally opposite change in the assumption used for prepayment rates. The actuarial assumptions used in the fair value of embedded derivatives which include assumptions related to lapses, withdrawals, and mortality, are based on experience studies performed by the Company in combination with available industry information and are reviewed on a periodic basis, at least annually. The significant unobservable inputs used in the fair value measurement of embedded derivatives are assumptions associated with policyholder experience and selected capital market assumptions for equity-indexed and variable annuities. The selected capital market assumptions, which include long-term implied volatilities, are projections based on short-term historical information. Changes in interest rates, equity indices, equity volatility, CVA, and actuarial assumptions regarding policyholder experience may result in significant fluctuations in the value of embedded derivatives. Fair value measurements associated with funds withheld reinsurance treaties are generally not materially sensitive to changes in unobservable inputs associated with policyholder experience. The primary drivers of change in these fair values are related to movements of credit spreads, which are generally observable. Increases (decreases) in market credit spreads tend to decrease (increase) the fair value of embedded derivatives. Increases (decreases) in the CVA assumption tend to decrease (increase) the magnitude of the fair value of embedded derivatives. Fair value measurements associated with variable annuity treaties are sensitive to both capital markets inputs and policyholder experience inputs. Increases (decreases) in lapse rates tend to decrease (increase) the value of the embedded derivatives associated with variable annuity treaties. Increases (decreases) in the long-term volatility assumption tend to increase (decrease) the fair value of embedded derivatives. Increases (decreases) in the CVA assumption tend to decrease (increase) the magnitude of the fair value of embedded derivatives. The actuarial assumptions used in the fair value of longevity and mortality swaps include assumptions related to the level and volatility of mortality. The assumptions are based on studies performed by the Company in combination with available industry information and are reviewed on a periodic basis, at least annually. The following table presents quantitative information about significant unobservable inputs used in Level 3 fair value measurements that are developed internally by the Company as of September 30, 2017 and December 31, 2016 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) September 30, 2017 December 31, 2016 September 30, 2017 December 31, 2016 Assets: Corporate securities $ 150,170 $ 167,815 Market comparable securities Liquidity premium 0-2% (1%) 0-2% (1%) U.S. government and agencies 23,251 24,488 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions 4,544 4,670 Market comparable securities Liquidity premium 1 % 1 % Funds withheld at interest- embedded derivatives 84,325 (22,529 ) Total return swap Mortality 0-100% (3%) 0-100% (2%) Lapse 0-35% (10%) 0-35% (8%) Withdrawal 0-5% (4%) 0-5% (3%) CVA 0-5% (1%) 0-5% (1%) Crediting rate 2-4% (3%) 2-4% (2%) Longevity swaps 37,827 26,958 Discounted cash flow Mortality 0-100% (2%) 0-100% (2%) Mortality improvement (10%)-10% (3%) (10%)-10% (3%) Liabilities: Interest sensitive contract liabilities- embedded derivatives- indexed annuities 821,821 805,672 Discounted cash flow Mortality 0-100% (3%) 0-100% (2%) Lapse 0-35% (10%) 0-35% (8%) Withdrawal 0-5% (4%) 0-5% (3%) Option budget projection 2-4% (3%) 2-4% (2%) Interest sensitive contract liabilities- embedded derivatives- variable annuities 168,119 184,636 Discounted cash flow Mortality 0-100% (1%) 0-100% (2%) Lapse 0-25% (5%) 0-25% (6%) Withdrawal 0-7% (3%) 0-7% (3%) CVA 0-5% (1%) 0-5% (1%) Long-term volatility 0-27% (9%) 0-27% (14%) Mortality swaps 1,683 2,462 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%) The Company recognizes transfers of assets and liabilities into and out of levels within the fair value hierarchy at the beginning of the quarter in which the actual event or change in circumstances that caused the transfer occurs. Assets and liabilities transferred into Level 3 are due to a lack of observable market transactions and price information. Assets and liabilities are transferred out of Level 3 when circumstances change such that significant inputs can be corroborated with market observable data. This may be due to a significant increase in market activity for the asset or liability, a specific event, one or more significant input(s) becoming observable. Transfers out of Level 3 were primarily the result of the Company obtaining observable pricing information or a third party pricing quotation that appropriately reflects the fair value of those assets and liabilities. In addition, certain transfers out of Level 3 were also due to ratings upgrades on mortgage-backed securities that had previously had below investment-grade ratings. Transfers from Level 1 to Level 2 are due to the lack of observable market data when pricing these securities, while transfers from Level 2 to Level 1 are due to an increase in the availability of market observable data in an active market. There were no transfers between Level 1 and Level 2 during the three and nine months ended September 30, 2016. The following tables present the transfers between Level 1 and Level 2 during the three and nine months ended September 30, 2017 (dollars in thousands): 2017 Transfers from Level 1 to Level 2 Transfers from Level 2 to Level 1 Three months ended September 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ — Nine months ended September 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ 88,674 The tables below provide a summary of the changes in fair value of Level 3 assets and liabilities for the three and nine months ended September 30, 2017 , as well as the portion of gains or losses included in income for the three and nine months ended September 30, 2017 attributable to unrealized gains or losses related to those assets and liabilities still held at September 30, 2017 (dollars in thousands): For the three months ended September 30, 2017: Fixed maturity securities - available-for-sale Corporate securities Canadian and Canadian provincial governments Residential mortgage- backed securities Asset-backed securities Fair value, beginning of period $ 1,291,054 $ 533,270 $ 148,685 $ 201,589 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (383 ) 3,460 (30 ) 160 Investment related gains (losses), net 396 — 44 — Included in other comprehensive income (2,700 ) (11,365 ) 104 (101 ) Purchases (1) 107,670 — 26,765 — Sales (1) (26,337 ) — (3,553 ) — Settlements (1) (88,551 ) — (3,645 ) (15,243 ) Transfers into Level 3 3,844 — 15 36,994 Transfers out of Level 3 (12,973 ) — (50,390 ) (78,202 ) Fair value, end of period $ 1,272,020 $ 525,365 $ 117,995 $ 145,197 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (394 ) $ 3,460 $ (27 ) $ 156 For the three months ended September 30, 2017 (continued): Fixed maturity securities available-for-sale Commercial U.S. government State Other foreign government, supranational and foreign government-sponsored enterprises Fair value, beginning of period $ 1,943 $ 23,567 $ 34,434 $ 11,994 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (116 ) 26 (1 ) Included in other comprehensive income 5 6 (208 ) (7 ) Purchases (1) — 134 — 495 Settlements (1) (1 ) (340 ) (35 ) — Transfers into Level 3 — — 7,295 — Transfers out of Level 3 — — — (6,853 ) Fair value, end of period $ 1,947 $ 23,251 $ 41,512 $ 5,628 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ — $ (116 ) $ 26 $ (1 ) For the three months ended September 30, 2017 (continued): Short-term Investments Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 3,548 $ 61,281 $ 33,349 $ (974,631 ) $ (1,552 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 23,

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information The accounting policies of the segments are the same as those described in the Summary of Significant Accounting Policies in Note 2 of the consolidated financial statements accompanying the 2016 Annual Report. The Company measures segment performance primarily based on profit or loss from operations before income taxes. There are no intersegment reinsurance transactions and the Company does not have any material long-lived assets. The Company allocates capital to its segments based on an internally developed economic capital model, the purpose of which is to measure the risk in the business and to provide a basis upon which capital is deployed. The economic capital model considers the unique and specific nature of the risks inherent in the Company’s businesses. As a result of the economic capital allocation process, a portion of investment income is attributed to the segments based on the level of allocated capital. In addition, the segments are charged for excess capital utilized above the allocated economic capital basis. This charge is included in policy acquisition costs and other insurance expenses. The Company has geographic-based and business-based operational segments. Geographic-based operations are further segmented into traditional and financial solutions businesses. Information related to revenues, income (loss) before income taxes and total assets of the Company for each reportable segment are summarized below (dollars in thousands). Three months ended September 30, Nine months ended September 30, Revenues: 2017 2016 2017 2016 U.S. and Latin America: Traditional $ 1,521,383 $ 1,444,917 $ 4,532,584 $ 4,339,737 Financial Solutions 264,170 276,135 834,992 620,117 Total 1,785,553 1,721,052 5,367,576 4,959,854 Canada: Traditional 281,095 280,959 814,643 827,871 Financial Solutions 12,430 12,359 36,240 34,897 Total 293,525 293,318 850,883 862,768 Europe, Middle East and Africa: Traditional 360,972 289,070 1,024,978 880,346 Financial Solutions 77,041 99,752 230,435 248,485 Total 438,013 388,822 1,255,413 1,128,831 Asia Pacific: Traditional 561,660 427,647 1,628,419 1,299,417 Financial Solutions 16,932 19,037 55,368 56,153 Total 578,592 446,684 1,683,787 1,355,570 Corporate and Other 49,627 50,701 125,667 145,190 Total $ 3,145,310 $ 2,900,577 $ 9,283,326 $ 8,452,213 Three months ended September 30, Nine months ended September 30, Income (loss) before income taxes: 2017 2016 2017 2016 U.S. and Latin America: Traditional $ 160,512 $ 77,081 $ 281,066 $ 239,609 Financial Solutions 89,118 102,714 299,689 196,672 Total 249,630 179,795 580,755 436,281 Canada: Traditional 28,789 34,275 80,953 97,679 Financial Solutions 4,472 1,160 12,489 3,880 Total 33,261 35,435 93,442 101,559 Europe, Middle East and Africa: Traditional 15,421 8,515 40,751 14,233 Financial Solutions 30,953 43,786 91,776 96,679 Total 46,374 52,301 132,527 110,912 Asia Pacific: Traditional 26,564 19,822 121,574 95,464 Financial Solutions (229 ) 7,549 11,020 16,029 Total 26,335 27,371 132,594 111,493 Corporate and Other (15,438 ) (7,302 ) (51,997 ) (11,842 ) Total $ 340,162 $ 287,600 $ 887,321 $ 748,403 Assets: September 30, 2017 December 31, 2016 U.S. and Latin America: Traditional $ 18,707,824 $ 18,140,825 Financial Solutions 16,101,746 13,712,106 Total 34,809,570 31,852,931 Canada: Traditional 4,177,125 3,846,682 Financial Solutions 88,609 85,405 Total 4,265,734 3,932,087 Europe, Middle East and Africa: Traditional 2,978,701 2,559,124 Financial Solutions 4,094,518 3,876,131 Total 7,073,219 6,435,255 Asia Pacific: Traditional 4,750,652 3,968,081 Financial Solutions 1,187,514 676,281 Total 5,938,166 4,644,362 Corporate and Other 6,607,342 6,233,244 Total $ 58,694,031 $ 53,097,879

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Commitments, Contingencies and Guarantees Commitments Funding of Investments The Company’s commitments to fund investments as of September 30, 2017 and December 31, 2016 are presented in the following table (dollars in thousands): September 30, 2017 December 31, 2016 Limited partnership interests and real estate joint ventures $ 349,157 $ 332,169 Commercial mortgage loans 75,492 126,248 Bank loans and private placements 51,479 58,318 Equity release mortgages 156,777 130,324 The Company anticipates that the majority of its current commitments will be invested over the next five years; however, these commitments could become due any time at the request of the counterparties. Investments in limited partnership interests and real estate joint ventures are carried at cost or reported using the equity method and included in other invested assets in the condensed consolidated balance sheets. Bank loans and private placements are carried at fair value and included in fixed maturity securities available-for-sale. Equity release mortgages are carried at unpaid principal balances, net of any amortized premium or discount and valuation allowance and included in other invested assets. Contingencies Litigation The Company is subject to litigation in the normal course of its business. The Company currently has no material litigation. A legal reserve is established when the Company is notified of an arbitration demand or litigation or is notified that an arbitration demand or litigation is imminent, it is probable that the Company will incur a loss as a result and the amount of the probable loss is reasonably capable of being estimated. Other Contingencies The Company indemnifies its directors and officers as provided in its charters and by-laws. Since this indemnity generally is not subject to limitation with respect to duration or amount, the Company does not believe that it is possible to determine the maximum potential amount due under this indemnity in the future. Guarantees Statutory Reserve Support RGA, through wholly-owned subsidiaries, has committed to provide statutory reserve support to third parties, in exchange for a fee, by funding loans if certain defined events occur. Such statutory reserves are required under the U.S. Valuation of Life Policies Model Regulation (commonly referred to as Regulation XXX for term life insurance policies and Regulation A-XXX for universal life secondary guarantees). The third parties have recourse to RGA should the subsidiary fail to provide the required funding, however, as of September 30, 2017 , the Company does not believe that it will be required to provide any funding under these commitments as the occurrence of the defined events is considered remote. The following table presents the maximum potential obligation for these commitments as of September 30, 2017 (dollars in millions): Commitment Period: Maximum Potential Obligation 2023 $ 500.0 2033 450.0 2034 2,000.0 2035 1,314.2 2036 2,932.0 2037 5,750.0 Other Guarantees RGA has issued guarantees to third parties on behalf of its subsidiaries for the payment of amounts due under certain securities borrowing and repurchase arrangements, financing arrangements and office lease obligations, whereby, if a subsidiary fails to meet an obligation, RGA or one of its other subsidiaries will make a payment to fulfill the obligation. Additionally, in limited circumstances, treaty guarantees are granted to ceding companies in order to provide them additional security, particularly in cases where RGA’s subsidiary is relatively new, unrated, or not of a significant size, relative to the ceding company. Liabilities supported by the treaty guarantees, before consideration for any legally offsetting amounts due from the guaranteed party are reflected on the Company’s condensed consolidated balance sheets in future policy benefits. Potential guaranteed amounts of future payments will vary depending on production levels and underwriting results. Guarantees related to securities borrowing and repurchase arrangements provide additional security to third parties should a subsidiary fail to provide securities when due. RGA’s guarantees issued as of September 30, 2017 and December 31, 2016 are reflected in the following table (dollars in thousands): September 30, 2017 December 31, 2016 Treaty guarantees $ 936,032 $ 902,216 Treaty guarantees, net of assets in trust 810,870 780,786 Securities borrowing and repurchase arrangements 295,285 263,820 Financing arrangements 100,602 119,073 Lease obligations 1,895 2,428

Income Tax

Income Tax	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Tax Provision for income tax expense differed from the amounts computed by applying the U.S. federal income tax statutory rate of 35.0% to pre-tax income as a result of the following for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Tax provision at U.S. statutory rate $ 119,057 $ 100,660 $ 310,562 $ 261,941 Increase (decrease) in income taxes resulting from: Foreign tax rate differing from U.S. tax rate (3,635 ) (2,335 ) (14,049 ) (14,617 ) Differences in tax bases in foreign jurisdictions 2,126 (7,078 ) (14,633 ) (21,567 ) Deferred tax valuation allowance (2,501 ) 4,411 11,627 13,698 Amounts related to tax audit contingencies 299 (3,979 ) (873 ) (175 ) Corporate rate changes (1,139 ) — (2,332 ) — Subpart F 64 1,779 1,390 3,212 Foreign tax credits 1,230 (1,934 ) (834 ) (2,655 ) Equity compensation excess benefit (2,762 ) — (7,226 ) — Return to provision adjustments 452 (1,996 ) 133 (2,227 ) Other, net (620 ) (647 ) (1,737 ) (501 ) Total provision for income taxes $ 112,571 $ 88,881 $ 282,028 $ 237,109 Effective tax rate 33.1 % 30.9 % 31.8 % 31.7 % The effective tax rate for the third quarter of 2017 was lower than the U.S. Statutory rate of 35.0% primarily as a result of income generated in non-U.S. jurisdictions with lower tax rates than the U.S. The first nine months of 2017 also includes a reduction related to differences in tax bases in foreign jurisdictions and a tax benefit from the filing of amended returns, which was partially offset with a valuation allowance established related to amended return filings. The third quarter of 2016 effective tax rate was lower than the U.S. Statutory rate of 35.0% primarily as a result of effectively settling an uncertain tax position during the quarter and adjustments related to the filing of the US Federal Income tax return. The first nine months of 2016 effective tax rate was lower than the U.S. Statutory rate of 35.0% primarily as a result of tax benefits from income in non-U.S. jurisdictions with lower tax rates than the U.S.

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans The components of net periodic benefit costs, included in other operating expenses on the condensed consolidated statements of income, for the three and nine months ended September 30, 2017 and 2016 were as follows (dollars in thousands): Pension Benefits Other Benefits Three months ended September 30, Three months ended September 30, 2017 2016 2017 2016 Service cost $ 2,699 $ 2,479 $ 465 $ 131 Interest cost 1,314 1,168 459 408 Expected return on plan assets (1,554 ) (1,285 ) — — Amortization of prior service cost 85 76 (675 ) (467 ) Amortization of prior actuarial loss 1,081 1,040 580 137 Settlements 256 — — — Net periodic benefit cost $ 3,881 $ 3,478 $ 829 $ 209 Pension Benefits Other Benefits Nine months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Service cost $ 8,098 $ 7,437 $ 1,907 $ 2,162 Interest cost 3,943 3,503 1,589 1,694 Expected return on plan assets (4,662 ) (3,854 ) — — Amortization of prior service cost 254 229 (986 ) (467 ) Amortization of prior actuarial loss 3,244 3,121 1,494 1,370 Settlements 769 — — — Net periodic benefit cost $ 11,646 $ 10,436 $ 4,004 $ 4,759 The Company has made $5.0 million in pension contributions during the first nine months of 2017 and expects to make total pension contributions between $5.0 million and $10.0 million in 2017.

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2017
Retrocession Arrangements And Reinsurance Ceded Receivables [Abstract]
Retrocession Arrangements and Reinsurance Ceded Receivables	Reinsurance Retrocession reinsurance treaties do not relieve the Company from its obligations to direct writing companies. Failure of retrocessionaires to honor their obligations could result in losses to the Company. Consequently, allowances would be established for amounts deemed uncollectible. At September 30, 2017 and December 31, 2016 , no allowances were deemed necessary. The Company regularly evaluates the financial condition of the insurance companies from which it assumes and to which it cedes reinsurance. Retrocessions are arranged through the Company’s retrocession pools for amounts in excess of the Company’s retention limit. As of September 30, 2017 and December 31, 2016 , all rated retrocession pool participants followed by the A.M. Best Company were rated “A- (excellent)” or better. The Company verifies retrocession pool participants’ ratings on a quarterly basis. For a majority of the retrocessionaires that were not rated, security in the form of letters of credit or trust assets has been posted. In addition, the Company performs annual financial reviews of its retrocessionaires to evaluate financial stability and performance. In addition to its third party retrocessionaires, various RGA reinsurance subsidiaries retrocede amounts in excess of their retention to affiliated subsidiaries. The following table presents information for the Company’s reinsurance ceded receivable assets, including the respective amount and A.M. Best rating for each reinsurer representing in excess of five percent of the total as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Reinsurer A.M. Best Rating Amount % of Total Amount % of Total Reinsurer A A+ $ 291,115 37.4 $ 240,894 35.2 % Reinsurer B A+ 203,584 26.1 183,881 26.9 Reinsurer C A+ 65,528 8.4 68,832 10.1 Reinsurer D A++ 40,860 5.2 36,202 5.3 Reinsurer E A+ 40,387 5.2 35,484 5.2 Other reinsurers 137,644 17.7 118,679 17.3 Total $ 779,118 100.0 % $ 683,972 100.0 % Included in the total reinsurance ceded receivables balance were $268.1 million and $242.0 million of claims recoverable, of which $0.9 million and $4.0 million were in excess of 90 days past due, as of September 30, 2017 and December 31, 2016 , respectively.

New Accounting Standards

New Accounting Standards	9 Months Ended
	Sep. 30, 2017
Accounting Changes and Error Corrections [Abstract]
New Accounting Standards	New Accounting Standards Changes to the general accounting principles are established by the Financial Accounting Standards Board (“FASB”) in the form of accounting standards updates to the FASB Accounting Standards Codification™. Accounting standards updates not listed below were assessed and determined to be either not applicable or are expected to have minimal impact on the Company’s condensed consolidated financial statements. Adoption of New Accounting Standards Stock Compensation In March 2016, the FASB updated the general accounting principal for Stock Compensation which changed how companies account for certain aspects of share-based payment awards to employees. The updated guidance requires excess tax benefits and deficiencies from share-based payment awards be recorded in income tax expense in the income statement. Previously, excess tax benefits and deficiencies were recognized in shareholders’ equity or deferred taxes on the balance sheet depending on the tax situation of the Company. In addition, the updated guidance also changes the accounting for forfeitures and statutory tax withholding requirements, as well as the classification in the statement of cash flows. The new standard generally requires a modified retrospective transition through a cumulative-effect adjustment as of the beginning of the period of adoption, with certain provisions requiring either a prospective or retrospective transition. The Company adopted the new guidance on January 1, 2017. Upon adoption, the Company recognized excess tax benefits of approximately $17.7 million in deferred tax assets that were previously not recognized in a cumulative-effect adjustment increasing retained earnings by $17.7 million . The Company also recorded excess tax benefits of approximately $2.8 million and $7.2 million in the provision for income taxes for the three and nine months ended September 30, 2017 , respectively. The number of weighted average diluted shares outstanding were also adjusted to exclude excess tax benefits from the assumed proceeds in the diluted shares calculation resulting in an immaterial increase in the number of dilutive shares outstanding. The Company also elected to continue estimating forfeitures for purposes of recognizing share-based compensation. Other aspects of the adoption of the updated guidance did not have a material impact to the Company’s financial statements. Future Adoption of New Accounting Standards Financial Instruments In January 2016, the FASB amended the general accounting principle for Financial Instruments, effective for the Company January 1, 2018. The amendment revises the accounting related to (1) the classification and measurement of investments in equity securities, (2) the presentation of certain fair value changes for financial liabilities measured at fair value, (3) certain disclosure requirements associated with the fair value of financial instruments. The new guidance should be applied by means of a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. The amendments related to equity securities without readily determinable fair values (including disclosure requirements) should be applied prospectively to equity investments that exist as of the date of adoption. The adoption of this amendment is not expected to have a material impact on the Company’s financial statements; however, it could result in net income volatility depending on the composition of the Company’s investment portfolio and changes in the fair value of equity securities. In June 2016, the FASB amended the existing impairment guidance of Financial Instruments. The amendment adds to U.S. GAAP an impairment model, known as current expected credit loss (“CECL”) model that is based on expected losses rather than incurred losses. For traditional and other receivables, held-to-maturity debt securities, loans and other instruments entities will be required to use the new forward-looking “expected loss” model that generally will result in earlier recognition of allowance for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses similar to what they do today, except the losses will be recognized as allowances rather than reduction to the amortized cost of the securities. This guidance is effective for the Company January 1, 2020, with early adoption permitted. The guidance will be adopted through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (that is, a modified-retrospective approach). The Company is currently evaluating the impact of this amendment on its condensed consolidated financial statements. Leases In February 2016, the FASB issued guidance which will replace most existing lease accounting guidance. The new standard, based on the principle that entities should recognize assets and liabilities arising from leases, does not significantly change the lessees’ recognition, measurement and presentation of expenses and cash flows from the previous accounting standard. Leases are classified as finance or operating. The new standard’s primary change is the requirement for entities to recognize a lease liability for payments and a right of use asset representing the right to use the leased asset during the term of operating lease arrangements. Lessees are permitted to make an accounting policy election to not recognize the asset and liability for leases with a term of twelve months or less. Lessors’ accounting is largely unchanged from the previous accounting standard. In addition, the new standard expands the disclosure requirements of lease arrangements. Lessees and lessors will use a modified retrospective transition approach, which includes a number of practical expedients. This guidance is effective for the Company January 1, 2019, with early adoption permitted. The Company is currently evaluating the impact of this amendment on its condensed consolidated financial statements. Income Taxes In October 2016, the FASB amended the general accounting principal for Income Taxes, effective for the Company January 1, 2018. The amendment requires entities to recognize the tax consequences of intercompany asset transfers, except for inventory, at the transaction date. Current GAAP prohibits entities from recognizing the income tax consequences from intercompany asset transfers. The seller defers any net tax effect, and the buyer is prohibited from recognizing a deferred tax asset on the difference between the newly created tax basis of the asset in its tax jurisdiction and its financial statement carrying amount as reported in the condensed consolidated financial statements. The amendment requires entities to recognize these tax consequences in the period in which the transfer occurred. There will be an immediate effect on earnings if the tax rates in the seller’s and buyer’s tax jurisdictions are different. This amendment will be applied using a modified retrospective transition method with a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. The adoption of this amendment will not have a material impact on the Company’s condensed consolidated financial statements. Derivative and Hedging In August 2017, the FASB updated the general accounting principal for Derivatives and Hedging. The updated guidance improves the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements and make certain targeted improvements to simplify the application of the hedge accounting in current GAAP related to the assessment of hedge effectiveness. The updated guidance is effective for the Company January 1, 2019, with early adoption permitted. The Company is currently evaluating the impact of this amending on its condensed consolidated financial statements.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Schedule Of Earnings Per Share Basic And Diluted By Common Class [Text Block]	The following table sets forth the computation of basic and diluted earnings per share on net income (in thousands, except per share information): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Earnings: Net income (numerator for basic and diluted calculations) $ 227,591 $ 198,719 $ 605,293 $ 511,294 Shares: Weighted average outstanding shares (denominator for basic calculation) 64,488 64,146 64,430 64,281 Equivalent shares from outstanding stock options 1,165 669 1,174 663 Denominator for diluted calculation 65,653 64,815 65,604 64,944 Earnings per share: Basic $ 3.53 $ 3.10 $ 9.39 $ 7.95 Diluted $ 3.47 $ 3.07 $ 9.23 $ 7.87

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2017
Stockholders' Equity Note [Abstract]
Schedule of Stock by Class [Table Text Block]	The changes in number of common stock shares, issued, held in treasury and outstanding are as follows for the periods indicated: Issued Held In Treasury Outstanding Balance, December 31, 2016 79,137,758 14,835,256 64,302,502 Common stock acquired — 208,680 (208,680 ) Stock-based compensation (1) — (274,449 ) 274,449 Balance, September 30, 2017 79,137,758 14,769,487 64,368,271 Issued Held In Treasury Outstanding Balance, December 31, 2015 79,137,758 13,933,232 65,204,526 Common stock acquired — 1,356,892 (1,356,892 ) Stock-based compensation (1) — (358,639 ) 358,639 Balance, September 30, 2016 79,137,758 14,931,485 64,206,273 (1) Represents net shares issued from treasury pursuant to the Company’s equity-based compensation programs.
Components of Accumulated Other Comprehensive Income	The balance of and changes in each component of accumulated other comprehensive income (loss) (“AOCI”) for the nine months ended September 30, 2017 and 2016 are as follows (dollars in thousands): Accumulated Currency Translation Adjustments Unrealized Appreciation (Depreciation) of Investments (1) Pension and Postretirement Benefits Total Balance, December 31, 2016 $ (172,541 ) $ 1,355,033 $ (43,163 ) $ 1,139,329 Other comprehensive income (loss) before reclassifications 23,117 671,564 (191 ) 694,490 Amounts reclassified to (from) AOCI — (51,407 ) 4,006 (47,401 ) Deferred income tax benefit (expense) 44,968 (204,287 ) (1,342 ) (160,661 ) Balance, September 30, 2017 $ (104,456 ) $ 1,770,903 $ (40,690 ) $ 1,625,757 Accumulated Currency Translation Adjustments Unrealized Appreciation (Depreciation) of Investments (1) Pension and Postretirement Benefits Total Balance, December 31, 2015 $ (181,151 ) $ 935,697 $ (46,262 ) $ 708,284 Other comprehensive income (loss) before reclassifications 68,271 2,191,823 (6,079 ) 2,254,015 Amounts reclassified to (from) AOCI — (109,145 ) 4,253 (104,892 ) Deferred income tax benefit (expense) (8,829 ) (636,902 ) 650 (645,081 ) Balance, September 30, 2016 $ (121,709 ) $ 2,381,473 $ (47,438 ) $ 2,212,326 (1) Includes cash flow hedges of $347 and $(2,496) as of September 30, 2017 and December 31, 2016 , respectively, and $(40,597) and $(29,397) as of September 30, 2016 and December 31, 2015 , respectively. See Note 5 - “Derivative Instruments” for additional information on cash flow hedges.
Reclassification Out Of Accumulated Other Comprehensive Income	The following table presents the amounts of AOCI reclassifications for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Amount Reclassified from AOCI Three months ended September 30, Nine months ended September 30, Details about AOCI Components 2017 2016 2017 2016 Affected Line Item in Statements of Income Net unrealized investment gains (losses): Net unrealized gains and losses on available-for-sale securities $ 10,515 $ 72,351 $ 39,032 $ 84,250 Investment related gains (losses), net Cash flow hedges - Currency/Interest rate 230 200 560 454 (1) Cash flow hedges - Forward bond purchase commitments 224 137 286 (120 ) (1) Deferred policy acquisition costs attributed to unrealized gains and losses 1,116 12,090 11,529 24,561 (2) Total 12,085 84,778 51,407 109,145 Provision for income taxes (3,991 ) (27,680 ) (16,015 ) (32,676 ) Net unrealized gains (losses), net of tax $ 8,094 $ 57,098 $ 35,392 $ 76,469 Amortization of defined benefit plan items: Prior service cost (credit) $ 590 $ 391 $ 732 $ 238 (3) Actuarial gains/(losses) (1,661 ) (1,177 ) (4,738 ) (4,491 ) (3) Total (1,071 ) (786 ) (4,006 ) (4,253 ) Provision for income taxes 375 276 1,402 1,489 Amortization of defined benefit plans, net of tax $ (696 ) $ (510 ) $ (2,604 ) $ (2,764 ) Total reclassifications for the period $ 7,398 $ 56,588 $ 32,788 $ 73,705 (1) See Note 5 - “Derivative Instruments” for additional information on cash flow hedges. (2) This AOCI component is included in the computation of the deferred policy acquisition cost. See Note 8 – “Deferred Policy Acquisition Costs” of the 2016 Annual Report for additional details. (3) This AOCI component is included in the computation of the net periodic pension cost. See Note 10 – “Employee Benefit Plans” for additional detai

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2017
Investments [Abstract]
Available For Sale Securities	The following tables provide information relating to investments in fixed maturity and equity securities by sector as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate securities $ 21,418,741 $ 1,209,999 $ 92,910 $ 22,535,830 61.9 % $ — Canadian and Canadian provincial governments 2,850,982 1,142,635 2,432 3,991,185 11.0 — Residential mortgage-backed securities 1,645,379 42,202 8,276 1,679,305 4.6 — Asset-backed securities 1,680,918 18,713 5,063 1,694,568 4.7 275 Commercial mortgage-backed securities 1,293,296 25,471 5,445 1,313,322 3.6 — U.S. government and agencies 1,621,053 13,614 30,998 1,603,669 4.4 — State and political subdivisions 614,099 52,919 5,987 661,031 1.8 — Other foreign government, supranational and foreign government-sponsored enterprises 2,765,500 145,025 7,693 2,902,832 8.0 — Total fixed maturity securities $ 33,889,968 $ 2,650,578 $ 158,804 $ 36,381,742 100.0 % $ 275 Non-redeemable preferred stock $ 41,878 $ 312 $ 3,289 $ 38,901 34.4 % Other equity securities 74,514 633 1,117 74,030 65.6 Total equity securities $ 116,392 $ 945 $ 4,406 $ 112,931 100.0 % December 31, 2016: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate securities $ 18,924,711 $ 911,618 $ 217,245 $ 19,619,084 61.1 % $ — Canadian and Canadian provincial governments 2,561,605 1,085,982 3,541 3,644,046 11.4 — Residential mortgage-backed securities 1,258,039 33,917 13,380 1,278,576 4.0 (375 ) Asset-backed securities 1,443,822 9,350 23,828 1,429,344 4.5 275 Commercial mortgage-backed securities 1,342,440 28,973 7,759 1,363,654 4.2 — U.S. government and agencies 1,518,702 12,644 63,044 1,468,302 4.6 — State and political subdivisions 566,761 37,499 12,464 591,796 1.8 — Other foreign government, supranational and foreign government-sponsored enterprises 2,595,707 123,054 19,938 2,698,823 8.4 — Total fixed maturity securities $ 30,211,787 $ 2,243,037 $ 361,199 $ 32,093,625 100.0 % $ (100 ) Non-redeemable preferred stock $ 55,812 $ 1,648 $ 6,337 $ 51,123 18.6 % Other equity securities 229,767 1,792 7,321 224,238 81.4 Total equity securities $ 285,579 $ 3,440 $ 13,658 $ 275,361 100.0 %
Schedule of Financial Instruments Owned and Pledged as Collateral [Table Text Block]	The following table includes fixed maturity securities pledged and received as collateral and assets in trust held to satisfy collateral requirements under derivative transactions and certain third-party reinsurance treaties as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities pledged as collateral $ 68,841 $ 72,365 $ 207,066 $ 210,676 Fixed maturity securities received as collateral n/a 461,237 n/a 300,925 Assets in trust held to satisfy collateral requirements 14,598,404 15,598,457 12,135,258 12,874,370
Concentration Risk Disclosure [Text Block]	The Company’s exposure to concentrations of credit risk from single issuers greater than 10% of the Company’s stockholders’ equity included securities of the U.S. government and its agencies as well as the securities disclosed below as of September 30, 2017 and December 31, 2016 (dollars in thousands). September 30, 2017 December 31, 2016 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities guaranteed or issued by: Canadian province of Quebec $ 1,115,505 $ 1,766,749 $ 1,004,261 $ 1,612,957 Canadian province of Ontario 932,872 1,231,201 832,764 1,126,433
Investments Classified By Contractual Maturity Date	The amortized cost and estimated fair value of fixed maturity securities classified as available-for-sale at September 30, 2017 are shown by contractual maturity in the table below (dollars in thousands). Actual maturities can differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Asset and mortgage-backed securities are shown separately in the table below, as they are not due at a single maturity date. Amortized Cost Estimated Fair Value Available-for-sale: Due in one year or less $ 910,821 $ 915,586 Due after one year through five years 7,339,134 7,618,692 Due after five years through ten years 9,581,912 10,090,704 Due after ten years 11,438,508 13,069,565 Asset and mortgage-backed securities 4,619,593 4,687,195 Total $ 33,889,968 $ 36,381,742
Fixed Maturity Holdings Industry Types Weighted Average Credit Ratings [Table Text Block]	The tables below show the major industry types of the Company’s corporate fixed maturity holdings as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017: Estimated Amortized Cost Fair Value % of Total Finance $ 7,797,576 $ 8,146,891 36.2 % Industrial 11,323,024 11,914,845 52.8 Utility 2,298,141 2,474,094 11.0 Total $ 21,418,741 $ 22,535,830 100.0 % December 31, 2016: Estimated Amortized Cost Fair Value % of Total Finance $ 6,725,199 $ 6,888,968 35.2 % Industrial 10,228,813 10,639,613 54.2 Utility 1,970,699 2,090,503 10.6 Total $ 18,924,711 $ 19,619,084 100.0 %
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Table Text Block]	The following table sets forth the amount of pre-tax credit loss impairments on fixed maturity securities held by the Company as of the dates indicated, for which a portion of the OTTI loss was recognized in AOCI, and the corresponding changes in such amounts (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Balance, beginning of period $ 3,677 $ 6,974 $ 6,013 $ 7,284 Credit loss OTTI previously recognized on securities which matured, paid down, prepaid or were sold during the period — — (2,336 ) (310 ) Balance, end of period $ 3,677 $ 6,974 $ 3,677 $ 6,974
Investments In Debt And Equity Securities Gross Unrealized Losses Disclosures	The following table presents the total gross unrealized losses for the 1,165 and 1,535 fixed maturity and equity securities as of September 30, 2017 and December 31, 2016 , respectively, where the estimated fair value had declined and remained below amortized cost by the indicated amount (dollars in thousands): September 30, 2017 December 31, 2016 Gross Unrealized Losses % of Total Gross Unrealized Losses % of Total Less than 20% $ 140,313 86.0 % $ 337,831 90.1 % 20% or more for less than six months 3,407 2.1 19,438 5.2 20% or more for six months or greater 19,490 11.9 17,588 4.7 Total $ 163,210 100.0 % $ 374,857 100.0 %
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block]	The following tables present the estimated fair values and gross unrealized losses, including other-than-temporary impairment losses reported in AOCI, for 1,165 and 1,535 fixed maturity and equity securities that have estimated fair values below amortized cost as of September 30, 2017 and December 31, 2016 , respectively (dollars in thousands). These investments are presented by class and grade of security, as well as the length of time the related fair value has remained below amortized cost. Less than 12 months 12 months or greater Total Gross Gross Gross September 30, 2017: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate securities $ 2,035,856 $ 15,923 $ 1,213,026 $ 49,422 $ 3,248,882 $ 65,345 Canadian and Canadian provincial governments 97,100 1,320 46,663 1,112 143,763 2,432 Residential mortgage-backed securities 507,372 5,084 154,469 3,189 661,841 8,273 Asset-backed securities 516,613 2,318 133,848 2,213 650,461 4,531 Commercial mortgage-backed securities 293,834 3,224 61,707 2,221 355,541 5,445 U.S. government and agencies 1,302,732 29,712 56,595 1,286 1,359,327 30,998 State and political subdivisions 53,977 743 62,530 5,156 116,507 5,899 Other foreign government, supranational and foreign government-sponsored enterprises 327,813 2,529 104,333 4,865 432,146 7,394 Total investment grade securities 5,135,297 60,853 1,833,171 69,464 6,968,468 130,317 Below investment grade securities: Corporate securities 170,023 3,780 95,089 23,785 265,112 27,565 Residential mortgage-backed securities — — 93 3 93 3 Asset-backed securities — — 5,611 532 5,611 532 State and political subdivisions 919 88 — — 919 88 Other foreign government, supranational and foreign government-sponsored enterprises 11,219 77 15,667 222 26,886 299 Total below investment grade securities 182,161 3,945 116,460 24,542 298,621 28,487 Total fixed maturity securities $ 5,317,458 $ 64,798 $ 1,949,631 $ 94,006 $ 7,267,089 $ 158,804 Non-redeemable preferred stock $ 6,712 $ 345 $ 25,983 $ 2,944 $ 32,695 $ 3,289 Other equity securities 6,446 396 58,206 721 64,652 1,117 Total equity securities $ 13,158 $ 741 $ 84,189 $ 3,665 $ 97,347 $ 4,406 Less than 12 months 12 months or greater Total Gross Gross Gross December 31, 2016: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate securities $ 4,661,706 $ 124,444 $ 549,273 $ 43,282 $ 5,210,979 $ 167,726 Canadian and Canadian provincial governments 101,578 3,541 — — 101,578 3,541 Residential mortgage-backed securities 490,473 9,733 112,216 3,635 602,689 13,368 Asset-backed securities 563,259 12,010 257,166 9,653 820,425 21,663 Commercial mortgage-backed securities 368,465 6,858 10,853 166 379,318 7,024 U.S. government and agencies 1,056,101 63,044 — — 1,056,101 63,044 State and political subdivisions 187,194 9,396 13,635 3,068 200,829 12,464 Other foreign government, supranational and foreign government-sponsored enterprises 524,236 13,372 51,097 2,981 575,333 16,353 Total investment grade securities 7,953,012 242,398 994,240 62,785 8,947,252 305,183 Below investment grade securities: Corporate securities 330,757 7,914 163,152 41,605 493,909 49,519 Residential mortgage-backed securities — — 412 12 412 12 Asset-backed securities 5,904 700 12,581 1,465 18,485 2,165 Commercial mortgage-backed securities 5,815 735 — — 5,815 735 Other foreign government, supranational and foreign government-sponsored enterprises 32,355 1,258 39,763 2,327 72,118 3,585 Total below investment grade securities 374,831 10,607 215,908 45,409 590,739 56,016 Total fixed maturity securities $ 8,327,843 $ 253,005 $ 1,210,148 $ 108,194 $ 9,537,991 $ 361,199 Non-redeemable preferred stock $ 10,831 $ 831 $ 21,879 $ 5,506 $ 32,710 $ 6,337 Other equity securities 202,068 7,020 6,751 301 208,819 7,321 Total equity securities $ 212,899 $ 7,851 $ 28,630 $ 5,807 $ 241,529 $ 13,658
Investment Income	Major categories of investment income, net of related expenses, consist of the following (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Fixed maturity securities available-for-sale $ 359,157 $ 325,089 $ 1,039,392 $ 961,096 Mortgage loans on real estate 50,040 39,802 138,829 121,494 Policy loans 15,404 15,391 45,870 47,897 Funds withheld at interest 102,144 104,609 327,089 273,482 Short-term investments and cash and cash equivalents 1,977 1,752 5,266 6,265 Other invested assets 47,595 21,138 90,488 57,896 Investment income 576,317 507,781 1,646,934 1,468,130 Investment expense (19,399 ) (18,054 ) (57,114 ) (53,471 ) Investment income, net of related expenses $ 556,918 $ 489,727 $ 1,589,820 $ 1,414,659
Gain Loss On Investments	Investment related gains (losses), net consist of the following (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Fixed maturity and equity securities available for sale: Other-than-temporary impairment losses on fixed maturity securities recognized in earnings $ (390 ) $ — $ (20,980 ) $ (34,663 ) Impairment losses on equity securities (889 ) — (889 ) — Gain on investment activity 19,522 46,346 91,635 127,153 Loss on investment activity (7,678 ) (9,054 ) (30,712 ) (43,397 ) Other impairment losses and change in mortgage loan provision (2,446 ) (262 ) (9,220 ) (2,111 ) Derivatives and other, net 14,534 49,594 109,637 37,020 Total investment related gains (losses), net $ 22,653 $ 86,624 $ 139,471 $ 84,002
Schedule of Repurchase Agreements [Table Text Block]	The following table includes the amount of borrowed securities, securities lent and securities collateral received as part of the securities lending program and repurchased/reverse repurchased securities pledged and received as of September 30, 2017 and December 31, 2016 (dollars in thousands). September 30, 2017 December 31, 2016 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Borrowed securities $ 360,475 $ 379,101 $ 263,820 $ 279,186 Securities lending: Securities loaned 117,219 121,958 74,389 73,625 Securities received n/a 120,000 n/a 80,000 Repurchase program/reverse repurchase program: Securities pledged 491,824 512,613 476,531 499,891 Securities received n/a 522,354 n/a 515,200
Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets [Table Text Block]	The following table presents information on the Company’s securities lending and repurchase transactions as of September 30, 2017 and December 31, 2016 (dollars in thousands). Collateral associated with certain borrowed securities is not included within the table, as the collateral pledged to each counterparty is the right to reinsurance treaty cash flows. September 30, 2017 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Securities lending transactions: Corporate securities $ — $ — $ — $ 121,958 $ 121,958 Total — — — 121,958 121,958 Repurchase transactions: Corporate securities — 1,472 5,402 175,258 182,132 Residential mortgage-backed securities — — — 87,418 87,418 U.S. government and agencies — — 23,206 196,040 219,246 Foreign government — — — 21,370 21,370 Other 2,447 — — — 2,447 Total 2,447 1,472 28,608 480,086 512,613 Total transactions $ 2,447 $ 1,472 $ 28,608 $ 602,044 $ 634,571 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 680,850 Amounts related to agreements not included in offsetting disclosure $ 46,279 December 31, 2016 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Securities lending transactions: Corporate securities $ — $ — $ 4,017 $ 69,608 $ 73,625 Total $ — $ — $ 4,017 $ 69,608 $ 73,625 Repurchase transactions: Corporate securities $ — $ — $ 3,220 $ 166,979 $ 170,199 Residential mortgage-backed securities — — — 92,546 92,546 U.S. government and agencies — — — 216,000 216,000 Foreign government — — — 19,900 19,900 Other 1,246 — — — 1,246 Total 1,246 — 3,220 495,425 499,891 Total borrowings $ 1,246 $ — $ 7,237 $ 565,033 $ 573,516 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 624,032 Amounts related to agreements not included in offsetting disclosure $ 50,516
Disclosure Of Real Estate Holdings By Property Type [Table Text Block]	The distribution of mortgage loans by property type is as follows as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Property type: Carrying Value % of Total Carrying Value % of Total Office building $ 1,426,673 32.9 % $ 1,270,113 33.6 % Retail 1,316,463 30.4 1,179,936 31.2 Industrial 891,051 20.6 713,461 18.8 Apartment 508,367 11.7 447,088 11.8 Other commercial 191,443 4.4 172,609 4.6 Recorded investment 4,333,997 100.0 % $ 3,783,207 100.0 % Unamortized balance of loan origination fees and expenses (2,531 ) — Valuation allowances (9,137 ) (7,685 ) Total mortgage loans on real estate $ 4,322,329 $ 3,775,522
Mortgage Loans Classified By Contractual Maturity Date [Table Text Block]	The maturities of the mortgage loans as of September 30, 2017 and December 31, 2016 are as follows (dollars in thousands): September 30, 2017 December 31, 2016 Recorded Investment % of Total Recorded Investment % of Total Due within five years $ 1,086,700 25.1 % $ 822,073 21.7 % Due after five years through ten years 2,334,113 53.8 2,099,559 55.5 Due after ten years 913,184 21.1 861,575 22.8 Total $ 4,333,997 100.0 % $ 3,783,207 100.0 %
Financing Receivable Credit Quality Indicators [Table Text Block]	The following tables set forth certain key credit quality indicators of the Company’s recorded investment in mortgage loans as of September 30, 2017 and December 31, 2016 (dollars in thousands): Recorded Investment Debt Service Ratios >1.20x 1.00x - 1.20x <1.00x Total % of Total September 30, 2017: Loan-to-Value Ratio 0% - 59.99% $ 2,060,277 $ 51,162 $ 4,698 $ 2,116,137 48.8 % 60% - 69.99% 1,515,469 86,613 44,358 1,646,440 38.0 70% - 79.99% 424,195 32,664 19,850 476,709 11.0 Greater than 80% 51,348 19,951 23,412 94,711 2.2 Total $ 4,051,289 $ 190,390 $ 92,318 $ 4,333,997 100.0 % Recorded Investment Debt Service Ratios >1.20x 1.00x - 1.20x <1.00x Total % of Total December 31, 2016: Loan-to-Value Ratio 0% - 59.99% $ 1,859,640 $ 64,749 $ 1,366 $ 1,925,755 50.8 % 60% - 69.99% 1,257,788 34,678 — 1,292,466 34.2 70% - 79.99% 370,092 20,869 24,369 415,330 11.0 Greater than 80% 114,297 — 35,359 149,656 4.0 Total $ 3,601,817 $ 120,296 $ 61,094 $ 3,783,207 100.0 %
Recorded Investment And Allowance For Credit Losses	The following table presents the recorded investment in mortgage loans, by method of measuring impairment, and the related valuation allowances as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Mortgage loans: Individually measured for impairment $ 5,856 $ 2,216 Collectively measured for impairment 4,328,141 3,780,991 Recorded investment $ 4,333,997 $ 3,783,207 Valuation allowances: Individually measured for impairment $ — $ — Collectively measured for impairment 9,137 7,685 Total valuation allowances $ 9,137 $ 7,685
Allowance For Mortgage Loan And Lease Losses Provision For Loss Net	Information regarding the Company’s loan valuation allowances for mortgage loans for the three and nine months ended September 30, 2017 and 2016 is as follows (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Balance, beginning of period $ 8,156 $ 6,499 $ 7,685 $ 6,813 Provision (release) 977 247 1,444 (67 ) Translation adjustment 4 — 8 — Balance, end of period $ 9,137 $ 6,746 $ 9,137 $ 6,746
Impaired Financing Receivables Table	Information regarding the portion of the Company’s mortgage loans that were impaired as of September 30, 2017 and December 31, 2016 is as follows (dollars in thousands): Unpaid Principal Balance Recorded Investment Related Allowance Carrying Value September 30, 2017: Impaired mortgage loans with no valuation allowance recorded $ 6,427 $ 5,856 $ — $ 5,856 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 6,427 $ 5,856 $ — $ 5,856 December 31, 2016: Impaired mortgage loans with no valuation allowance recorded $ 2,758 $ 2,216 $ — $ 2,216 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 2,758 $ 2,216 $ — $ 2,216 The Company’s average investment in impaired mortgage loans and the related interest income are reflected in the table below for the periods indicated (dollars in thousands): Three months ended September 30, 2017 2016 Average (1) Interest Income Average Recorded Investment (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 3,967 $ 33 $ 6,953 $ 107 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 3,967 $ 33 $ 6,953 $ 107 Nine months ended September 30, 2017 2016 Average (1) Interest Income Average (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 3,062 $ 100 $ 4,687 $ 324 Impaired mortgage loans with valuation allowance recorded — — 5,459 — Total impaired mortgage loans $ 3,062 $ 100 $ 10,146 $ 324 (1) Average recorded investment represents the average loan balances as of the beginning of period and all subsequent quarterly end of period balances.
Schedule Of Other Invested Assets [Table Text Block]	Carrying values of these assets as of September 30, 2017 and December 31, 2016 are as follows (dollars in thousands): September 30, 2017 December 31, 2016 Equity securities $ 112,931 $ 275,361 Limited partnership interests and real estate joint ventures 761,739 687,522 Derivatives 133,405 229,108 FVO contractholder-directed unit-linked investments 210,660 190,120 Other 313,788 209,829 Total other invested assets $ 1,532,523 $ 1,591,940

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of Derivative Instruments In Statement Of Financial Position Fair Value	The following table presents the notional amounts and gross fair value of derivative instruments prior to taking into account the netting effects of master netting agreements as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Notional Carrying Value/Fair Value Notional Carrying Value/Fair Value Amount Assets Liabilities Amount Assets Liabilities Derivatives not designated as hedging instruments: Interest rate swaps $ 946,726 $ 61,263 $ 1,825 $ 949,556 $ 78,405 $ 5,949 Financial futures 448,600 — — 475,968 — — Foreign currency forwards 6,000 (84 ) — 25,000 — 5,070 Consumer price index swaps 132,081 589 420 20,615 — 262 Credit default swaps 948,000 7,905 490 926,000 12,012 2,871 Equity options 541,532 20,006 — 525,894 33,459 — Longevity swaps 945,120 37,827 — 841,360 26,958 — Mortality swaps 50,000 — 1,683 50,000 — 2,462 Synthetic guaranteed investment contracts 9,119,434 — — 8,834,700 — — Embedded derivatives in: Modified coinsurance or funds withheld arrangements — 84,325 — — — 22,529 Indexed annuity products — — 821,821 — — 805,672 Variable annuity products — — 168,119 — — 184,636 Total non-hedging derivatives 13,137,493 211,831 994,358 12,649,093 150,834 1,029,451 Derivatives designated as hedging instruments: Interest rate swaps 435,000 — 22,133 435,000 27,901 31,223 Foreign currency swaps 796,489 71,032 13,876 928,505 104,359 734 Foreign currency forwards 331,135 1,418 10,203 — — — Total hedging derivatives 1,562,624 72,450 46,212 1,363,505 132,260 31,957 Total derivatives $ 14,700,117 $ 284,281 $ 1,040,570 $ 14,012,598 $ 283,094 $ 1,061,408
Offsetting Assets [Table Text Block]	The following table provides information relating to the Company’s derivative instruments as of September 30, 2017 and December 31, 2016 (dollars in thousands): Gross Amounts Not Offset in the Balance Sheet Gross Amounts Recognized Gross Amounts Offset in the Balance Sheet Net Amounts Presented in the Balance Sheet Financial Instruments (1) Cash Collateral Pledged/ Received Net Amount September 30, 2017: Derivative assets $ 199,956 $ (28,724 ) $ 171,232 $ (17,782 ) $ (174,120 ) $ (20,670 ) Derivative liabilities 50,630 (28,724 ) 21,906 (58,360 ) (30,771 ) (67,225 ) December 31, 2016: Derivative assets $ 283,094 $ (27,028 ) $ 256,066 $ (16,913 ) $ (254,498 ) $ (15,345 ) Derivative liabilities 48,571 (27,028 ) 21,543 (95,863 ) (1,441 ) (75,761 ) (1) Includes initial margin posted to a central clearing partner.
Offsetting Liabilities [Table Text Block]	The following table provides information relating to the Company’s derivative instruments as of September 30, 2017 and December 31, 2016 (dollars in thousands): Gross Amounts Not Offset in the Balance Sheet Gross Amounts Recognized Gross Amounts Offset in the Balance Sheet Net Amounts Presented in the Balance Sheet Financial Instruments (1) Cash Collateral Pledged/ Received Net Amount September 30, 2017: Derivative assets $ 199,956 $ (28,724 ) $ 171,232 $ (17,782 ) $ (174,120 ) $ (20,670 ) Derivative liabilities 50,630 (28,724 ) 21,906 (58,360 ) (30,771 ) (67,225 ) December 31, 2016: Derivative assets $ 283,094 $ (27,028 ) $ 256,066 $ (16,913 ) $ (254,498 ) $ (15,345 ) Derivative liabilities 48,571 (27,028 ) 21,543 (95,863 ) (1,441 ) (75,761 ) (1) Includes initial margin posted to a central clearing partner.
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The gain or loss on the hedged item attributable to a change in foreign currency and the offsetting gain or loss on the related foreign currency swaps as of September 30, 2017 and 2016, were (dollars in thousands): Type of Fair Value Hedge Hedged Item Gains (Losses) Recognized for Derivatives Gains (Losses) Recognized for Hedged Items Ineffectiveness Recognized in Investment Related Gains (Losses), net For the three months ended September 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 2,100 $ (2,100 ) $ — For the three months ended September 30, 2016: Foreign currency swaps Foreign-denominated fixed maturity securities $ 3,205 $ (3,205 ) $ — For the nine months ended September 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 9,541 $ (9,541 ) $ — For the nine months ended September 30, 2016: Foreign currency swaps Foreign-denominated fixed maturity securities $ 5,317 $ (5,317 ) $ —
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table presents the components of AOCI, before income tax, and the condensed consolidated income statement classification where the gain or loss is recognized related to cash flow hedges for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Three months ended September 30, 2017 2016 Balance beginning of period $ 7,690 $ (41,192 ) Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges (6,889 ) 932 Amounts reclassified to investment related (gains) losses, net (183 ) (116 ) Amounts reclassified to investment income (271 ) (221 ) Balance end of period $ 347 $ (40,597 ) Nine months ended September 30, 2017 2016 Balance beginning of period $ (2,496 ) $ (29,397 ) Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges 3,689 (10,866 ) Amounts reclassified to investment related (gains) losses, net (142 ) 53 Amounts reclassified to investment income (704 ) (387 ) Balance end of period $ 347 $ (40,597 )
Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The following table presents the effective portion of derivatives in cash flow hedging relationships on the condensed consolidated statements of income and the condensed consolidated statements of comprehensive income for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Effective Portion Derivative Type Gain (Loss) Deferred in OCI Gain (Loss) Reclassified into Income from OCI Investment Related Gains (Losses) Investment Income For the three months ended September 30, 2017: Interest rate $ (8,421 ) $ — $ — Currency/Interest rate 1,544 — 230 Forward bond purchase commitments (12 ) 183 41 Total $ (6,889 ) $ 183 $ 271 For the three months ended September 30, 2016: Interest rate $ (3,282 ) $ — $ — Currency/Interest rate 4,214 — 200 Forward bond purchase commitments — 116 21 Total $ 932 $ 116 $ 221 For the nine months ended September 30, 2017: Interest rate $ (6,205 ) $ — $ — Currency/Interest rate 9,894 — 560 Forward bond purchase commitments — 142 144 Total $ 3,689 $ 142 $ 704 For the nine months ended September 30, 2016: Interest rate $ (15,617 ) $ — $ — Currency/Interest rate 4,751 — 454 Forward bond purchase commitments — (53 ) (67 ) Total $ (10,866 ) $ (53 ) $ 387
Schedule of Net Investment Hedges, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The following table illustrates the Company’s net investments in foreign operations (“NIFO”) hedges for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Derivative Gains (Losses) Deferred in AOCI For the three months ended September 30, For the nine months ended September 30, Type of NIFO Hedge (1) (2) 2017 2016 2017 2016 Foreign currency swaps $ (35,198 ) $ 8,341 $ (60,723 ) $ (23,151 ) Foreign currency forwards 4,627 — 8,785 — Total $ (30,571 ) $ 8,341 $ (51,938 ) $ (23,151 ) (1) There were no sales or substantial liquidations of net investments in foreign operations that would have required the reclassification of gains or losses from accumulated other comprehensive income (loss) into investment income during the periods presented. (2) There was no ineffectiveness recognized for the Company’s hedges of net investments in foreign operations.
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	A summary of the effect of non-hedging derivatives, including embedded derivatives, on the Company’s condensed consolidated statements of income for the three and nine months ended September 30, 2017 and 2016 is as follows (dollars in thousands): Gain (Loss) for the three months ended September 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2017 2016 Interest rate swaps Investment related gains (losses), net $ 641 $ 4,122 Financial futures Investment related gains (losses), net (8,890 ) (11,677 ) Foreign currency forwards Investment related gains (losses), net 24 507 CPI swaps Investment related gains (losses), net 220 76 Credit default swaps Investment related gains (losses), net 4,137 6,672 Equity options Investment related gains (losses), net (8,295 ) (13,648 ) Longevity swaps Other revenues 3,334 8,921 Mortality swaps Other revenues (132 ) (400 ) Subtotal (8,961 ) (5,427 ) Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 23,044 49,078 Indexed annuity products Interest credited (13,133 ) (20,104 ) Variable annuity products Investment related gains (losses), net (6,205 ) 7,988 Total non-hedging derivatives $ (5,255 ) $ 31,535 Gain (Loss) for the nine months ended September 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2017 2016 Interest rate swaps Investment related gains (losses), net $ 12,318 $ 108,149 Financial futures Investment related gains (losses), net (28,107 ) (30,285 ) Foreign currency forwards Investment related gains (losses), net 577 6,584 CPI swaps Investment related gains (losses), net 211 (624 ) Credit default swaps Investment related gains (losses), net 15,374 13,536 Equity options Investment related gains (losses), net (34,757 ) (19,576 ) Longevity swaps Other revenues 7,180 11,402 Mortality swaps Other revenues (921 ) 222 Subtotal (28,125 ) 89,408 Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 106,854 33,795 Indexed annuity products Interest credited (35,490 ) (20,730 ) Variable annuity products Investment related gains (losses), net 16,518 (83,089 ) Total non-hedging derivatives $ 59,757 $ 19,384
Disclosure Of Credit Derivatives	The following table presents the estimated fair value, maximum amount of future payments and weighted average years to maturity of credit default swaps sold by the Company at September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Rating Agency Designation of Referenced Credit Obligations (1) Estimated Fair Value of Credit Default Swaps Maximum Amount of Future Payments under Credit Default Swaps (2) Weighted Average Years to Maturity (3) Estimated Fair Value of Credit Default Swaps Maximum Amount of Future Payments under Credit Default Swaps (2) Weighted Average Years to Maturity (3) AAA/AA+/AA/AA-/A+/A/A- Single name credit default swaps $ 2,975 $ 155,500 3.2 $ 1,726 $ 150,500 3.8 Subtotal 2,975 155,500 3.2 1,726 150,500 3.8 BBB+/BBB/BBB- Single name credit default swaps 4,209 368,200 3.2 1,426 347,200 3.7 Credit default swaps referencing indices 56 416,000 4.2 6,295 416,000 5.0 Subtotal 4,265 784,200 3.7 7,721 763,200 4.4 BB+/BB/BB- Single name credit default swaps 21 5,000 1.7 (477 ) 9,000 3.5 Subtotal 21 5,000 1.7 (477 ) 9,000 3.5 Total $ 7,261 $ 944,700 3.6 $ 8,970 $ 922,700 4.3 (1) The rating agency designations are based on ratings from Standard and Poor’s (“S&P”). (2) Assumes the value of the referenced credit obligations is zero. (3) The weighted average years to maturity of the credit default swaps is calculated based on weighted average notional amounts.
Changes In Estimated Fair Value Related To Embedded Derivatives	The related gains (losses) and the effect on net income after amortization of deferred acquisition costs (“DAC”) and income taxes for the three and nine months ended September 30, 2017 and 2016 are reflected in the following table (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Embedded derivatives in modco or funds withheld arrangements included in investment related gains $ 23,044 $ 49,078 $ 106,854 $ 33,795 After the associated amortization of DAC and taxes, the related amounts included in net income 7,515 9,653 36,300 1,683 Embedded derivatives in variable annuity contracts included in investment related gains (6,205 ) 7,988 16,518 (83,089 ) After the associated amortization of DAC and taxes, the related amounts included in net income (1,074 ) 2,595 30,785 (63,415 ) Amounts related to embedded derivatives in equity-indexed annuities included in benefits and expenses (13,133 ) (20,104 ) (35,490 ) (20,730 ) After the associated amortization of DAC and taxes, the related amounts included in net income (9,737 ) (13,397 ) (38,059 ) (9,979 )
Credit Risk	Information regarding the Company’s credit exposure related to its over-the-counter derivative contracts, centrally cleared derivative contracts and margin account for exchange-traded futures, excluding mortality swaps, at September 30, 2017 and December 31, 2016 are reflected in the following table (dollars in thousands): September 30, 2017 December 31, 2016 Estimated fair value of derivatives in net asset position $ 151,009 $ 236,985 Cash provided as collateral (1) 30,771 1,441 Securities pledged to counterparties as collateral (2) 58,360 95,863 Cash pledged from counterparties as collateral (3) (174,120 ) (254,498 ) Securities pledged from counterparties as collateral (4) (17,782 ) (16,913 ) Initial margin for cleared derivatives (2) (58,360 ) (73,571 ) Net amount after application of master netting agreements and collateral $ (10,122 ) $ (10,693 ) Margin account related to exchange-traded futures (5) $ 7,832 $ 9,687 (1) Consists of receivable from counterparty, included in other assets. (2) Included in available-for-sale securities, primarily consists of U.S. Treasury and government agency securities. (3) Included in cash and cash equivalents, with obligation to return cash collateral recorded in other liabilities. (4) Consists of U.S. Treasury and government securities. (5) Included in other assets.

Fair Value of Assets and Liab24

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Schedule Of Fair Value Assets and Liabilities Measured on Recurring Basis Table Text Block	Assets and liabilities measured at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 are summarized below (dollars in thousands): September 30, 2017: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate securities $ 22,535,830 $ 615,433 $ 20,648,377 $ 1,272,020 Canadian and Canadian provincial governments 3,991,185 — 3,465,820 525,365 Residential mortgage-backed securities 1,679,305 — 1,561,310 117,995 Asset-backed securities 1,694,568 — 1,549,371 145,197 Commercial mortgage-backed securities 1,313,322 — 1,311,375 1,947 U.S. government and agencies 1,603,669 1,480,357 100,061 23,251 State and political subdivisions 661,031 — 619,519 41,512 Other foreign government supranational and foreign government-sponsored enterprises 2,902,832 319,147 2,578,057 5,628 Total fixed maturity securities – available-for-sale 36,381,742 2,414,937 31,833,890 2,132,915 Funds withheld at interest – embedded derivatives 84,325 — — 84,325 Cash equivalents 332,186 332,186 — — Short-term investments 56,454 — 53,095 3,359 Other invested assets: Non-redeemable preferred stock 38,901 38,901 — — Other equity securities 74,030 74,030 — — Derivatives: Interest rate swaps 46,258 — 46,258 — Foreign currency forwards 1,418 — 1,418 — CPI swaps 230 — 230 — Credit default swaps 6,903 — 6,903 — Equity options 9,700 — 9,700 — Foreign currency swaps 68,896 — 68,896 — FVO contractholder-directed unit-linked investments 210,660 209,136 1,524 — Total other invested assets 456,996 322,067 134,929 — Other assets - longevity swaps 37,827 — — 37,827 Total $ 37,349,530 $ 3,069,190 $ 32,021,914 $ 2,258,426 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 989,940 $ — $ — $ 989,940 Other liabilities: Derivatives: Interest rate swaps 8,953 — 8,953 — Foreign currency forwards 10,287 — 10,287 — CPI swaps 61 — 61 — Credit default swaps (512 ) — (512 ) — Equity options (10,306 ) — (10,306 ) — Foreign currency swaps 11,740 — 11,740 — Mortality swaps 1,683 — — 1,683 Total $ 1,011,846 $ — $ 20,223 $ 991,623 December 31, 2016: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate securities $ 19,619,084 $ 310,995 $ 18,035,836 $ 1,272,253 Canadian and Canadian provincial governments 3,644,046 — 3,168,081 475,965 Residential mortgage-backed securities 1,278,576 — 1,118,285 160,291 Asset-backed securities 1,429,344 — 1,210,064 219,280 Commercial mortgage-backed securities 1,363,654 — 1,342,509 21,145 U.S. government and agencies 1,468,302 1,345,755 98,059 24,488 State and political subdivisions 591,796 — 550,130 41,666 Other foreign government, supranational and foreign government-sponsored enterprises 2,698,823 276,729 2,409,225 12,869 Total fixed maturity securities – available-for-sale 32,093,625 1,933,479 27,932,189 2,227,957 Funds withheld at interest – embedded derivatives (22,529 ) — — (22,529 ) Cash equivalents 338,601 338,601 — — Short-term investments 44,241 8,276 32,619 3,346 Other invested assets: Non-redeemable preferred stock 51,123 38,317 12,806 — Other equity securities 224,238 224,238 — — Derivatives: Interest rate swaps 93,508 — 93,508 — Credit default swaps 9,136 — 9,136 — Equity options 26,070 — 26,070 — Foreign currency swaps 100,394 — 100,394 — FVO contractholder-directed unit-linked investments 190,120 188,891 1,229 — Other 11,036 11,036 — — Total other invested assets 705,625 462,482 243,143 — Other assets - longevity swaps 26,958 — — 26,958 Total $ 33,186,521 $ 2,742,838 $ 28,207,951 $ 2,235,732 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 990,308 $ — $ — $ 990,308 Other liabilities: Derivatives: Interest rate swaps 24,374 — 24,374 — Foreign currency forwards 5,070 — 5,070 — CPI swaps 262 — 262 — Credit default swaps (5 ) — (5 ) — Equity options (7,389 ) — (7,389 ) — Foreign currency swaps (3,231 ) — (3,231 ) — Mortality swaps 2,462 — — 2,462 Total $ 1,011,851 $ — $ 19,081 $ 992,770
Fair Value Unobservable Input Measurements [Table Text Block]	The following table presents quantitative information about significant unobservable inputs used in Level 3 fair value measurements that are developed internally by the Company as of September 30, 2017 and December 31, 2016 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) September 30, 2017 December 31, 2016 September 30, 2017 December 31, 2016 Assets: Corporate securities $ 150,170 $ 167,815 Market comparable securities Liquidity premium 0-2% (1%) 0-2% (1%) U.S. government and agencies 23,251 24,488 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions 4,544 4,670 Market comparable securities Liquidity premium 1 % 1 % Funds withheld at interest- embedded derivatives 84,325 (22,529 ) Total return swap Mortality 0-100% (3%) 0-100% (2%) Lapse 0-35% (10%) 0-35% (8%) Withdrawal 0-5% (4%) 0-5% (3%) CVA 0-5% (1%) 0-5% (1%) Crediting rate 2-4% (3%) 2-4% (2%) Longevity swaps 37,827 26,958 Discounted cash flow Mortality 0-100% (2%) 0-100% (2%) Mortality improvement (10%)-10% (3%) (10%)-10% (3%) Liabilities: Interest sensitive contract liabilities- embedded derivatives- indexed annuities 821,821 805,672 Discounted cash flow Mortality 0-100% (3%) 0-100% (2%) Lapse 0-35% (10%) 0-35% (8%) Withdrawal 0-5% (4%) 0-5% (3%) Option budget projection 2-4% (3%) 2-4% (2%) Interest sensitive contract liabilities- embedded derivatives- variable annuities 168,119 184,636 Discounted cash flow Mortality 0-100% (1%) 0-100% (2%) Lapse 0-25% (5%) 0-25% (6%) Withdrawal 0-7% (3%) 0-7% (3%) CVA 0-5% (1%) 0-5% (1%) Long-term volatility 0-27% (9%) 0-27% (14%) Mortality swaps 1,683 2,462 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%)
Fair Value Inputs, Liabilities, Quantitative Information [Table Text Block]	The following table presents quantitative information about significant unobservable inputs used in Level 3 fair value measurements that are developed internally by the Company as of September 30, 2017 and December 31, 2016 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) September 30, 2017 December 31, 2016 September 30, 2017 December 31, 2016 Assets: Corporate securities $ 150,170 $ 167,815 Market comparable securities Liquidity premium 0-2% (1%) 0-2% (1%) U.S. government and agencies 23,251 24,488 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions 4,544 4,670 Market comparable securities Liquidity premium 1 % 1 % Funds withheld at interest- embedded derivatives 84,325 (22,529 ) Total return swap Mortality 0-100% (3%) 0-100% (2%) Lapse 0-35% (10%) 0-35% (8%) Withdrawal 0-5% (4%) 0-5% (3%) CVA 0-5% (1%) 0-5% (1%) Crediting rate 2-4% (3%) 2-4% (2%) Longevity swaps 37,827 26,958 Discounted cash flow Mortality 0-100% (2%) 0-100% (2%) Mortality improvement (10%)-10% (3%) (10%)-10% (3%) Liabilities: Interest sensitive contract liabilities- embedded derivatives- indexed annuities 821,821 805,672 Discounted cash flow Mortality 0-100% (3%) 0-100% (2%) Lapse 0-35% (10%) 0-35% (8%) Withdrawal 0-5% (4%) 0-5% (3%) Option budget projection 2-4% (3%) 2-4% (2%) Interest sensitive contract liabilities- embedded derivatives- variable annuities 168,119 184,636 Discounted cash flow Mortality 0-100% (1%) 0-100% (2%) Lapse 0-25% (5%) 0-25% (6%) Withdrawal 0-7% (3%) 0-7% (3%) CVA 0-5% (1%) 0-5% (1%) Long-term volatility 0-27% (9%) 0-27% (14%) Mortality swaps 1,683 2,462 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Level Transfers [Table Text Block]	The following tables present the transfers between Level 1 and Level 2 during the three and nine months ended September 30, 2017 (dollars in thousands): 2017 Transfers from Level 1 to Level 2 Transfers from Level 2 to Level 1 Three months ended September 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ — Nine months ended September 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ 88,674
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	The tables below provide a summary of the changes in fair value of Level 3 assets and liabilities for the three and nine months ended September 30, 2017 , as well as the portion of gains or losses included in income for the three and nine months ended September 30, 2017 attributable to unrealized gains or losses related to those assets and liabilities still held at September 30, 2017 (dollars in thousands): For the three months ended September 30, 2017: Fixed maturity securities - available-for-sale Corporate securities Canadian and Canadian provincial governments Residential mortgage- backed securities Asset-backed securities Fair value, beginning of period $ 1,291,054 $ 533,270 $ 148,685 $ 201,589 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (383 ) 3,460 (30 ) 160 Investment related gains (losses), net 396 — 44 — Included in other comprehensive income (2,700 ) (11,365 ) 104 (101 ) Purchases (1) 107,670 — 26,765 — Sales (1) (26,337 ) — (3,553 ) — Settlements (1) (88,551 ) — (3,645 ) (15,243 ) Transfers into Level 3 3,844 — 15 36,994 Transfers out of Level 3 (12,973 ) — (50,390 ) (78,202 ) Fair value, end of period $ 1,272,020 $ 525,365 $ 117,995 $ 145,197 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (394 ) $ 3,460 $ (27 ) $ 156 For the three months ended September 30, 2017 (continued): Fixed maturity securities available-for-sale Commercial U.S. government State Other foreign government, supranational and foreign government-sponsored enterprises Fair value, beginning of period $ 1,943 $ 23,567 $ 34,434 $ 11,994 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (116 ) 26 (1 ) Included in other comprehensive income 5 6 (208 ) (7 ) Purchases (1) — 134 — 495 Settlements (1) (1 ) (340 ) (35 ) — Transfers into Level 3 — — 7,295 — Transfers out of Level 3 — — — (6,853 ) Fair value, end of period $ 1,947 $ 23,251 $ 41,512 $ 5,628 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ — $ (116 ) $ 26 $ (1 ) For the three months ended September 30, 2017 (continued): Short-term Investments Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 3,548 $ 61,281 $ 33,349 $ (974,631 ) $ (1,552 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 23,044 — (10,047 ) — Interest credited — — — (8,335 ) — Included in other comprehensive income (3 ) — 1,144 — 1 Other revenues — — 3,334 — (132 ) Purchases (1) 3,164 — — (18,736 ) — Settlements (1) (114 ) — — 21,809 — Transfers out of Level 3 (3,236 ) — — — Fair value, end of period $ 3,359 $ 84,325 $ 37,827 $ (989,940 ) $ (1,683 ) Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment related gains (losses), net — 23,044 — (11,900 ) — Other revenues — — 3,334 — (132 ) Interest credited — — — (30,145 ) — For the nine months ended September 30, 2017: Fixed maturity securities - available-for-sale Corporate securities Canadian and Canadian provincial governments Residential mortgage- backed securities Asset-backed securities Fair value, beginning of period $ 1,272,253 $ 475,965 $ 160,291 $ 219,280 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (1,202 ) 9,731 (304 ) 1,689 Investment related gains (losses), net 7,592 — 524 — Interest credited Included in other comprehensive income (2,300 ) 39,669 2,716 6,802 Purchases (1) 257,671 — 72,582 45,215 Sales (1) (49,511 ) — (18,624 ) — Settlements (1) (234,552 ) — (15,084 ) (60,966 ) Transfers into Level 3 35,042 — 5,515 75,752 Transfers out of Level 3 (12,973 ) — (89,621 ) (142,575 ) Fair value, end of period $ 1,272,020 $ 525,365 $ 117,995 $ 145,197 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (1,213 ) $ 9,731 $ (155 ) $ 556 Investment related gains (losses), net (2,788 ) — (346 ) — For the nine months ended September 30, 2017 (continued): Fixed maturity securities available-for-sale Commercial U.S. government State Other foreign government, supranational and foreign government-sponsored enterprises Fair value, beginning of period $ 21,145 $ 24,488 $ 41,666 $ 12,869 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses 709 (348 ) (68 ) (1 ) Investment related gains (losses), net (595 ) — — — Included in other comprehensive income (57 ) 269 (228 ) (210 ) Other revenues — — — — Purchases (1) — 370 — 495 Sales (1) (3,720 ) — — — Settlements (1) (5,403 ) (1,528 ) (309 ) (672 ) Transfers into Level 3 — — 7,295 — Transfers out of Level 3 (10,132 ) — (6,844 ) (6,853 ) Fair value, end of period $ 1,947 $ 23,251 $ 41,512 $ 5,628 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ — $ (348 ) $ (68 ) $ (1 ) For the nine months ended September 30, 2017 (continued): Short-term Investments Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 3,346 $ (22,529 ) $ 26,958 $ (990,308 ) $ (2,462 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 106,854 — 9,005 — Interest credited — — — (20,408 ) — Included in other comprehensive income 1 — 3,689 — 1 Other revenues — — 7,180 — (922 ) Purchases (1) 3,520 — — (51,276 ) — Settlements (1) (272 ) — — 63,047 1,700 Transfers out of Level 3 (3,236 ) — — — — Fair value, end of period $ 3,359 $ 84,325 $ 37,827 $ (989,940 ) $ (1,683 ) Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment related gains (losses), net — 106,854 — 2,934 — Other revenues — — 7,180 — (922 ) Interest credited — — — (83,456 ) — (1) The amount reported within purchases, sales and settlements is the purchase price (for purchases) and the sales/settlement proceeds (for sales and settlements) based upon the actual date purchased or sold/settled. Items purchased and sold/settled in the same period are excluded from the rollforward. The Company had no issuances during the period. The tables below provide a summary of the changes in fair value of Level 3 assets and liabilities for the three and nine months ended September 30, 2016 , as well as the portion of gains or losses included in income for the three and nine months ended September 30, 2016 attributable to unrealized gains or losses related to those assets and liabilities still held at September 30, 2016 (dollars in thousands): For the three months ended September 30, 2016: Fixed maturity securities - available-for-sale Corporate securities Canadian and Canadian provincial governments Residential mortgage- backed securities Asset-backed securities Commercial mortgage- backed securities U.S. government and agencies Fair value, beginning of period $ 1,297,382 $ 554,192 $ 165,979 $ 298,816 $ 37,935 $ 26,255 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (567 ) 3,085 (40 ) 173 304 (122 ) Investment related gains (losses), net 17,917 — — — — — Included in other comprehensive income (19,635 ) 16,342 2,597 3,410 (94 ) (135 ) Purchases (1) 54,492 — 27,548 5,013 — 147 Sales (1) (26,320 ) — — — — — Settlements (1) (44,110 ) — (6,935 ) (18,602 ) (1 ) (312 ) Transfers into Level 3 — — 1,544 28,285 — — Transfers out of Level 3 (23,255 ) — — (93,444 ) (637 ) — Fair value, end of period $ 1,255,904 $ 573,619 $ 190,693 $ 223,651 $ 37,507 $ 25,833 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (489 ) $ 3,085 $ (40 ) $ 173 $ 304 $ (122 ) For the three months ended September 30, 2016 (continued): Fixed maturity securities available-for-sale State Other foreign government, supranational and foreign government-sponsored enterprises Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 35,246 $ 13,706 $ (91,981 ) $ 17,781 $ (1,125,380 ) $ (1,997 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses 10 — — — — — Investment related gains (losses), net — — 49,078 — 7,988 — Interest credited — — — — (20,104 ) — Included in other comprehensive income 553 48 — 327 — — Other revenues — — — 8,921 — (400 ) Purchases (1) 1,986 — — — (11,853 ) — Sales (1) — — — — — — Settlements (1) (32 ) (328 ) — — 19,225 329 Transfers into Level 3 — — — — — — Transfers out of Level 3 — — — — — — Fair value, end of period $ 37,763 $ 13,426 $ (42,903 ) $ 27,029 $ (1,130,124 ) $ (2,068 ) Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ 10 $ — $ — $ — $ — $ — Investment related gains (losses), net — — 49,078 — 3,969 — Other revenues — — — 8,921 — (400 ) Interest credited — — — — (39,329 ) — For the nine months ended September 30, 2016: Fixed maturity securities - available-for-sale Corporate securities Canadian and Canadian provincial governments Residential mortgage- backed securities Asset-backed securities Commercial mortgage- backed securities U.S. government and agencies Fair value, beginning of period $ 1,226,970 $ 416,076 $ 330,649 $ 303,836 $ 68,563 $ 26,265 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (1,986 ) 9,136 (411 ) 599 1,437 (367 ) Investment related gains (losses), net (3,939 ) — (1,922 ) 1,101 (3,289 ) — Interest credited — — — — — — Included in other comprehensive income 36,438 148,407 2,104 (4,324 ) (2,453 ) 922 Other revenues — — — — — — Purchases (1) 195,070 — 99,776 102,063 1,545 404 Sales (1) (36,803 ) — (167,684 ) (38,681 ) (25,976 ) — Settlements (1) (141,065 ) — (31,839 ) (26,523 ) (138 ) (1,391 ) Transfers into Level 3 10,206 — 1,544 53,081 — — Transfers out of Level 3 (28,987 ) — (41,524 ) (167,501 ) (2,182 ) — Fair value, end of period $ 1,255,904 $ 573,619 $ 190,693 $ 223,651 $ 37,507 $ 25,833 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (1,917 ) $ 9,136 $ 2 $ 523 $ 1,335 $ (367 ) For the nine months ended September 30, 2016 (continued): Fixed maturity securities available-for-sale State Other foreign government, supranational and foreign government-sponsored enterprises Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 38,342 $ 14,065 $ (76,698 ) $ 14,996 $ (1,070,584 ) $ (2,619 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses 205 — — — — — Investment related gains (losses), net — — 33,795 — (83,089 ) — Interest credited — — — — (20,730 ) — Included in other comprehensive income 1,725 336 — 631 — — Other revenues — — — 11,402 — 222 Purchases (1) 1,986 — — — (9,817 ) — Sales (1) — — — — — — Settlements (1) (290 ) (975 ) — — 54,096 329 Transfers into Level 3 — — — — — — Transfers out of Level 3 (4,205 ) — — — — — Fair value, end of period $ 37,763 $ 13,426 $ (42,903 ) $ 27,029 $ (1,130,124 ) $ (2,068 ) Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ 205 $ — $ — $ — $ — $ — Investment related gains (losses), net — — 33,795 — (92,842 ) — Other revenues — — — 11,402 — 222 Interest credited — — — — (74,826 ) — (1) The amount reported within purchases, sales and settlements is the purchase price (for purchases) and the sales/settlement proceeds (for sales and settlements) based upon the actual date purchased or sold/settled. Items purchased and sold/settled in the same period are excluded from the rollforward. The Company had no issuances during the period.
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Table Text Block]	The following table presents information for assets measured at estimated fair value on a nonrecurring basis during the periods presented and still held at the reporting date (for example, when there is evidence of impairment). The estimated fair values for these assets were determined using significant unobservable inputs (Level 3). Carrying Value After Measurement Net Investment Gains (Losses) At September 30, Three months ended September 30, Nine months ended September 30, (dollars in thousands) 2017 2016 2017 2016 2017 2016 Mortgage loans (1) $ — $ 6,913 $ — $ 747 $ — $ 45 Limited partnership interests (2) 4,656 4,460 (896 ) — (7,204 ) (2,039 ) Private equities (3) 106 — (531 ) — (531 ) — (1) Estimated fair values for impaired mortgage loans are based on internal valuation models using unobservable inputs or, if the loans are in foreclosure or are otherwise determined to be collateral dependent, are based on external appraisals of the underlying collateral. (2) The impaired limited partnership interests presented above were accounted for using the cost method. Impairments on these cost method investments were recognized at estimated fair value determined using the net asset values of the Company’s ownership interest as provided in the financial statements of the investees. The market for these investments has limited activity and price transparency. (3) The fair value of the Company’s private equity investments is based on external valuation models.
Financial Instruments Carrying Amounts And Estimated Fair Value [Table Text Block]	The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments, which were not measured at fair value on a recurring basis, as of September 30, 2017 and December 31, 2016 (dollars in thousands). This table excludes any payables or receivables for collateral under repurchase agreements and other transactions. The estimated fair value of the excluded amount approximates carrying value as they equal the amount of cash collateral received/paid. September 30, 2017: Carrying Value Estimated Fair Value Fair Value Measurement Using: Level 1 Level 2 Level 3 NAV Assets: Mortgage loans on real estate $ 4,322,329 $ 4,494,964 $ — $ — $ 4,494,964 $ — Policy loans 1,340,146 1,340,146 — 1,340,146 — — Funds withheld at interest (1) 5,931,416 6,309,369 — — 6,309,369 — Cash and cash equivalents (2) 872,404 872,404 872,404 — — — Short-term investments (2) 24,128 24,128 24,128 — — — Other invested assets (2) 601,905 627,650 28,267 68,342 230,355 300,686 Accrued investment income 420,111 420,111 — 420,111 — — Liabilities: Interest-sensitive contract liabilities (1) $ 12,616,104 $ 12,960,161 $ — $ — $ 12,960,161 $ — Long-term debt 2,778,480 2,997,791 — — 2,997,791 — Collateral finance and securitization notes 796,825 708,342 — — 708,342 — December 31, 2016: Carrying Value Estimated Fair Value Fair Value Measurement Using: Level 1 Level 2 Level 3 NAV Assets: Mortgage loans on real estate $ 3,775,522 $ 3,786,987 $ — $ — $ 3,786,987 $ — Policy loans 1,427,602 1,427,602 — 1,427,602 — — Funds withheld at interest (1) 5,893,381 6,193,166 — — 6,193,166 — Cash and cash equivalents (2) 862,117 862,117 862,117 — — — Short-term investments (2) 32,469 32,469 32,469 — — — Other invested assets (2) 477,132 510,640 26,294 55,669 131,904 296,773 Accrued investment income 347,173 347,173 — 347,173 — — Liabilities: Interest-sensitive contract liabilities (1) $ 10,225,099 $ 10,234,544 $ — $ — $ 10,234,544 $ — Long-term debt 3,088,635 3,186,173 — — 3,186,173 — Collateral finance and securitization notes 840,700 745,805 — — 745,805 — (1) Carrying values presented herein differ from those presented in the condensed consolidated balance sheets because certain items within the respective financial statement caption are embedded derivatives and are measured at fair value on a recurring basis. (2) Carrying values presented herein differ from those presented in the condensed consolidated balance sheets because certain items within the respective financial statement caption are measured at fair value on a recurring basis.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Reconciliation Of Revenue From Segments To Consolidated Text Block	Information related to revenues, income (loss) before income taxes and total assets of the Company for each reportable segment are summarized below (dollars in thousands). Three months ended September 30, Nine months ended September 30, Revenues: 2017 2016 2017 2016 U.S. and Latin America: Traditional $ 1,521,383 $ 1,444,917 $ 4,532,584 $ 4,339,737 Financial Solutions 264,170 276,135 834,992 620,117 Total 1,785,553 1,721,052 5,367,576 4,959,854 Canada: Traditional 281,095 280,959 814,643 827,871 Financial Solutions 12,430 12,359 36,240 34,897 Total 293,525 293,318 850,883 862,768 Europe, Middle East and Africa: Traditional 360,972 289,070 1,024,978 880,346 Financial Solutions 77,041 99,752 230,435 248,485 Total 438,013 388,822 1,255,413 1,128,831 Asia Pacific: Traditional 561,660 427,647 1,628,419 1,299,417 Financial Solutions 16,932 19,037 55,368 56,153 Total 578,592 446,684 1,683,787 1,355,570 Corporate and Other 49,627 50,701 125,667 145,190 Total $ 3,145,310 $ 2,900,577 $ 9,283,326 $ 8,452,213
Reconciliation Of Operating Profit Loss From Segments To Consolidated Text Block	Three months ended September 30, Nine months ended September 30, Income (loss) before income taxes: 2017 2016 2017 2016 U.S. and Latin America: Traditional $ 160,512 $ 77,081 $ 281,066 $ 239,609 Financial Solutions 89,118 102,714 299,689 196,672 Total 249,630 179,795 580,755 436,281 Canada: Traditional 28,789 34,275 80,953 97,679 Financial Solutions 4,472 1,160 12,489 3,880 Total 33,261 35,435 93,442 101,559 Europe, Middle East and Africa: Traditional 15,421 8,515 40,751 14,233 Financial Solutions 30,953 43,786 91,776 96,679 Total 46,374 52,301 132,527 110,912 Asia Pacific: Traditional 26,564 19,822 121,574 95,464 Financial Solutions (229 ) 7,549 11,020 16,029 Total 26,335 27,371 132,594 111,493 Corporate and Other (15,438 ) (7,302 ) (51,997 ) (11,842 ) Total $ 340,162 $ 287,600 $ 887,321 $ 748,403
Reconciliation Of Assets From Segment To Consolidated Text Block	Assets: September 30, 2017 December 31, 2016 U.S. and Latin America: Traditional $ 18,707,824 $ 18,140,825 Financial Solutions 16,101,746 13,712,106 Total 34,809,570 31,852,931 Canada: Traditional 4,177,125 3,846,682 Financial Solutions 88,609 85,405 Total 4,265,734 3,932,087 Europe, Middle East and Africa: Traditional 2,978,701 2,559,124 Financial Solutions 4,094,518 3,876,131 Total 7,073,219 6,435,255 Asia Pacific: Traditional 4,750,652 3,968,081 Financial Solutions 1,187,514 676,281 Total 5,938,166 4,644,362 Corporate and Other 6,607,342 6,233,244 Total $ 58,694,031 $ 53,097,879

Commitments, Contingencies an26

Commitments, Contingencies and Guarantees (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Fair Value, Off-balance Sheet Risks [Table Text Block]	The Company’s commitments to fund investments as of September 30, 2017 and December 31, 2016 are presented in the following table (dollars in thousands): September 30, 2017 December 31, 2016 Limited partnership interests and real estate joint ventures $ 349,157 $ 332,169 Commercial mortgage loans 75,492 126,248 Bank loans and private placements 51,479 58,318 Equity release mortgages 156,777 130,324
Other Commitments [Table Text Block]	The following table presents the maximum potential obligation for these commitments as of September 30, 2017 (dollars in millions): Commitment Period: Maximum Potential Obligation 2023 $ 500.0 2033 450.0 2034 2,000.0 2035 1,314.2 2036 2,932.0 2037 5,750.0
Schedule of Guarantor Obligations [Table Text Block]	RGA’s guarantees issued as of September 30, 2017 and December 31, 2016 are reflected in the following table (dollars in thousands): September 30, 2017 December 31, 2016 Treaty guarantees $ 936,032 $ 902,216 Treaty guarantees, net of assets in trust 810,870 780,786 Securities borrowing and repurchase arrangements 295,285 263,820 Financing arrangements 100,602 119,073 Lease obligations 1,895 2,428

Income Tax (Tables)

Income Tax (Tables)	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Provision for income tax expense differed from the amounts computed by applying the U.S. federal income tax statutory rate of 35.0% to pre-tax income as a result of the following for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Tax provision at U.S. statutory rate $ 119,057 $ 100,660 $ 310,562 $ 261,941 Increase (decrease) in income taxes resulting from: Foreign tax rate differing from U.S. tax rate (3,635 ) (2,335 ) (14,049 ) (14,617 ) Differences in tax bases in foreign jurisdictions 2,126 (7,078 ) (14,633 ) (21,567 ) Deferred tax valuation allowance (2,501 ) 4,411 11,627 13,698 Amounts related to tax audit contingencies 299 (3,979 ) (873 ) (175 ) Corporate rate changes (1,139 ) — (2,332 ) — Subpart F 64 1,779 1,390 3,212 Foreign tax credits 1,230 (1,934 ) (834 ) (2,655 ) Equity compensation excess benefit (2,762 ) — (7,226 ) — Return to provision adjustments 452 (1,996 ) 133 (2,227 ) Other, net (620 ) (647 ) (1,737 ) (501 ) Total provision for income taxes $ 112,571 $ 88,881 $ 282,028 $ 237,109 Effective tax rate 33.1 % 30.9 % 31.8 % 31.7 %

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Schedule Of Defined Benefit Plans Disclosures Text Block	The components of net periodic benefit costs, included in other operating expenses on the condensed consolidated statements of income, for the three and nine months ended September 30, 2017 and 2016 were as follows (dollars in thousands): Pension Benefits Other Benefits Three months ended September 30, Three months ended September 30, 2017 2016 2017 2016 Service cost $ 2,699 $ 2,479 $ 465 $ 131 Interest cost 1,314 1,168 459 408 Expected return on plan assets (1,554 ) (1,285 ) — — Amortization of prior service cost 85 76 (675 ) (467 ) Amortization of prior actuarial loss 1,081 1,040 580 137 Settlements 256 — — — Net periodic benefit cost $ 3,881 $ 3,478 $ 829 $ 209 Pension Benefits Other Benefits Nine months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Service cost $ 8,098 $ 7,437 $ 1,907 $ 2,162 Interest cost 3,943 3,503 1,589 1,694 Expected return on plan assets (4,662 ) (3,854 ) — — Amortization of prior service cost 254 229 (986 ) (467 ) Amortization of prior actuarial loss 3,244 3,121 1,494 1,370 Settlements 769 — — — Net periodic benefit cost $ 11,646 $ 10,436 $ 4,004 $ 4,759

Reinsurance (Tables)

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2017
Retrocession Arrangements And Reinsurance Ceded Receivables [Abstract]
Ceded Credit Risk [Table Text Block]	The following table presents information for the Company’s reinsurance ceded receivable assets, including the respective amount and A.M. Best rating for each reinsurer representing in excess of five percent of the total as of September 30, 2017 and December 31, 2016 (dollars in thousands): September 30, 2017 December 31, 2016 Reinsurer A.M. Best Rating Amount % of Total Amount % of Total Reinsurer A A+ $ 291,115 37.4 $ 240,894 35.2 % Reinsurer B A+ 203,584 26.1 183,881 26.9 Reinsurer C A+ 65,528 8.4 68,832 10.1 Reinsurer D A++ 40,860 5.2 36,202 5.3 Reinsurer E A+ 40,387 5.2 35,484 5.2 Other reinsurers 137,644 17.7 118,679 17.3 Total $ 779,118 100.0 % $ 683,972 100.0 %

Earnings Per Share (Reconciliat

Earnings Per Share (Reconciliation of the Numerators and Denominators of the Basic and Diluted Per Shares) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Net income (numerator for basic and diluted calculations)	$ 227,591	$ 198,719	$ 605,293	$ 511,294
Shares:
Weighted average outstanding shares (denominator for basic calculation)	64,488	64,146	64,430	64,281
Equivalent shares from outstanding stock options	1,165	669	1,174	663
Denominator for diluted calculation	65,653	64,815	65,604	64,944
Earnings Per Share:
Basic earnings per share	$ 3.53	$ 3.10	$ 9.39	$ 7.95
Diluted earnings per share	$ 3.47	$ 3.07	$ 9.23	$ 7.87

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - shares shares in Thousands	3 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Stock Compensation Plan [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount	300	700
Stock Options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount	100	0

Equity (Common Stock Changes In

Equity (Common Stock Changes In Number of Shares Issued, Held In Treasury and Outstanding) (Details) - shares		3 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Common Stock, Shares, Issued		79,137,758		79,137,758
Treasury Stock, Shares, Acquired		200,000
Common Stock Issuable [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		79,137,758	79,137,758	79,137,758	79,137,758
Treasury Stock, Shares, Acquired		0	0
Stock Based Compensation Shares	[1]	0	0
Common Stock Held In Treasury [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		14,769,487	14,931,485	14,835,256	13,933,232
Treasury Stock, Shares, Acquired		208,680	1,356,892
Stock Based Compensation Shares	[1]	(274,449)	(358,639)
Common Stock Outstanding [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		64,368,271	64,206,273	64,302,502	65,204,526
Treasury Stock, Shares, Acquired		(208,680)	(1,356,892)
Stock Based Compensation Shares	[1]	(274,449)	(358,639)
[1]	Represents net shares issued from treasury pursuant to the Company’s equity-based compensation programs.

Equity (Balance of and Changes

Equity (Balance of and Changes in Each Component of AOCI) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Accumulated other comprehensive income		$ 1,625,757	$ 2,212,326	$ 1,139,329	$ 708,284
Other Comprehensive Income (Loss), before Reclassifications, before Tax		694,490	2,254,015
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		(47,401)	(104,892)
Other Comprehensive Income (Loss), Tax		160,661	645,081
Accumulated Translation Adjustment [Member]
Accumulated other comprehensive income		(104,456)	(121,709)	(172,541)	(181,151)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		23,117	68,271
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		0	0
Other Comprehensive Income (Loss), Tax		44,968	(8,829)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated other comprehensive income	[1]	1,770,903	2,381,473	1,355,033	935,697
Other Comprehensive Income (Loss), before Reclassifications, before Tax	[1]	671,564	2,191,823
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	[1]	(51,407)	(109,145)
Other Comprehensive Income (Loss), Tax	[1]	204,287	636,902
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated other comprehensive income		(40,690)	(47,438)	$ (43,163)	$ (46,262)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(191)	(6,079)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		4,006	4,253
Other Comprehensive Income (Loss), Tax		$ 1,342	$ (650)
[1]	Includes cash flow hedges of $347 and $(2,496) as of September 30, 2017 and December 31, 2016, respectively, and $(40,597) and $(29,397) as of September 30, 2016 and December 31, 2015, respectively. See Note 5 - “Derivative Instruments” for additional information on cash flow hedges.

Equity (Balance of and Change34

Equity (Balance of and Changes in Each Component of AOCI) (Footnote) (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 347	$ (40,597)	$ 7,690	$ (41,192)	$ 347	$ (40,597)	$ (2,496)	$ (29,397)

Equity (Schedule of Reclassific

Equity (Schedule of Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2017		Sep. 30, 2016
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		$ 23,043		$ 86,624		$ 160,451		$ 118,665
Investment income		556,918		489,727		1,589,820		1,414,659
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		340,162		287,600		887,321		748,403
Income Tax Expense (Benefit)		(112,571)		(88,881)		(282,028)		(237,109)
Net income		227,591		198,719		605,293		511,294
Unrealized Appreciation Depreciation Of Investments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		12,085		84,778		51,407		109,145
Income Tax Expense (Benefit)		(3,991)		(27,680)		(16,015)		(32,676)
Net income		8,094		57,098		35,392		76,469
Unrealized Appreciation Depreciation Of Investments [Member] | Unrealized Gains Losses On Available For Sale Securities [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		10,515		72,351		39,032		84,250
Unrealized Appreciation Depreciation Of Investments [Member] | Interest Rate Swap [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[1]	230		200		560		454
Unrealized Appreciation Depreciation Of Investments [Member] | Forward Contracts [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[1]	224		137		286		(120)
Unrealized Appreciation Depreciation Of Investments [Member] | DAC Attributed To Unrealized Gains Losses [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Deferred policy acquisition costs attributed to unrealized gains and losses		1,116	[1]	12,090	[1]	(11,529)	[2]	24,561	[2]
Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		(1,071)		(786)		(4,006)		(4,253)
Income Tax Expense (Benefit)		375		276		1,402		1,489
Net income		(696)		(510)		(2,604)		(2,764)
Amounts Reclassified From AOCI [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		7,398		56,588		32,788		73,705
Prior Service Cost [Member] | Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Prior service cost		590	[2]	391	[2]	732	[3]	238	[3]
Actuarial Gains Losses [Member] | Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Actuarial gains/(losses)		$ (1,661)	[2]	$ (1,177)	[2]	$ 4,738	[3]	$ (4,491)	[3]
[1]	See Note 5 - “Derivative Instruments” for additional information on cash flow hedges.
[2]	This AOCI component is included in the computation of the deferred policy acquisition cost. See Note 8 – “Deferred Policy Acquisition Costs” of the 2016 Annual Report for additional details.
[3]	This AOCI component is included in the computation of the net periodic pension cost. See Note 10 – “Employee Benefit Plans” for additional details.

Equity (Narrative) (Details)

Equity (Narrative) (Details) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017USD ($)shares	Sep. 30, 2017USD ($)
Equity [Abstract]
Stock Repurchase Program, Authorized Amount	$ 400	$ 400
Treasury Stock, Shares, Acquired | shares	0.2
Treasury Stock, Value, Acquired, Cost Method		$ 26.9

Equity Based Compensation (Narr

Equity Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity compensation expense	$ 17.1	$ 27.1
Stock appreciation rights granted	200,000
Stock appreciation rights granted, weighted average exercise price (per share)	$ 129.72
Performance contingent units	200,000
Shares Granted To Non Employee Directors	7,696
Options exercisable (shares)	1,600,000
Options exercisable, weighted average price (per share)	$ 60.77
Options, remaining term	4 years 7 months
Compensation cost not yet recognized	$ 32.5
Period for recognition	1 year 2 months

Investments (Investments in Fix

Investments (Investments in Fixed Maturity and Equity Securities Available-for-Sale by Sector) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 21,418,741	$ 18,924,711
Estimated Fair Value	$ 22,535,830	$ 19,619,084
% of Total	100.00%	100.00%
Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 33,889,968	$ 30,211,787
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2,650,578	2,243,037
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	158,804	361,199
Estimated Fair Value	$ 36,381,742	$ 32,093,625
% of Total	100.00%	100.00%
Other-than-temporary impairments in AOCI	$ 275	$ 100
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	116,392	285,579
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	945	3,440
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	4,406	13,658
Estimated Fair Value	$ 112,931	$ 275,361
% of Total	100.00%	100.00%
Corporate Debt Securities [Member] | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 21,418,741	$ 18,924,711
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,209,999	911,618
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	92,910	217,245
Estimated Fair Value	$ 22,535,830	$ 19,619,084
% of Total	61.90%	61.10%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Canadian and Canadian provincial governments | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,850,982	2,561,605
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,142,635	1,085,982
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2,432	3,541
Estimated Fair Value	$ 3,991,185	$ 3,644,046
% of Total	11.00%	11.40%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Residential mortgage-backed securities | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,645,379	1,258,039
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	42,202	33,917
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	8,276	13,380
Estimated Fair Value	$ 1,679,305	$ 1,278,576
% of Total	4.60%	4.00%
Other-than-temporary impairments in AOCI	$ 0	$ 375
Asset-backed securities | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,680,918	1,443,822
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	18,713	9,350
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5,063	23,828
Estimated Fair Value	$ 1,694,568	$ 1,429,344
% of Total	4.70%	4.50%
Other-than-temporary impairments in AOCI	$ 275	$ 275
Commercial Mortgage Backed Securities [Member] | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,293,296	1,342,440
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	25,471	28,973
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5,445	7,759
Estimated Fair Value	$ 1,313,322	$ 1,363,654
% of Total	3.60%	4.20%
Other-than-temporary impairments in AOCI	$ 0	$ 0
US Treasury and Government [Member] | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,621,053	1,518,702
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	13,614	12,644
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	30,998	63,044
Estimated Fair Value	$ 1,603,669	$ 1,468,302
% of Total	4.40%	4.60%
Other-than-temporary impairments in AOCI	$ 0	$ 0
US States and Political Subdivisions Debt Securities [Member] | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	614,099	566,761
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	52,919	37,499
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5,987	12,464
Estimated Fair Value	$ 661,031	$ 591,796
% of Total	1.80%	1.80%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Foreign Government Debt Securities [Member] | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,765,500	2,595,707
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	145,025	123,054
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	7,693	19,938
Estimated Fair Value	$ 2,902,832	$ 2,698,823
% of Total	8.00%	8.40%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Nonredeemable Preferred Stock [Member] | Equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	41,878	55,812
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	312	1,648
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	3,289	6,337
Estimated Fair Value	$ 38,901	$ 51,123
% of Total	34.40%	18.60%
Other equity securities | Equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 74,514	$ 229,767
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	633	1,792
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,117	7,321
Estimated Fair Value	$ 74,030	$ 224,238
% of Total	65.60%	81.40%

Investments (Fixed Maturity Sec

Investments (Fixed Maturity Securities Pledged And Received As Collateral) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 21,418,741	$ 18,924,711
Available-for-sale Securities	22,535,830	19,619,084
Collateral Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	68,841	207,066
Available-for-sale Securities	72,365	210,676
Collateral Received Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	461,237	300,925
Reported Value Measurement [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets Held-in-trust	14,598,404	12,135,258
Estimate of Fair Value Measurement [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets Held-in-trust	$ 15,598,457	$ 12,874,370

Investments (Exposure To Concen

Investments (Exposure To Concentrations Of Credit Risk) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 21,418,741	$ 18,924,711
Available-for-sale Securities	22,535,830	19,619,084
Canadian Province Of Quebec Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	932,872	832,764
Available-for-sale Securities	1,231,201	1,126,433
Canadian Province Of Ontario Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,115,505	1,004,261
Available-for-sale Securities	$ 1,766,749	$ 1,612,957

Investments (Amortized Cost and

Investments (Amortized Cost and Fair Value of Fixed Maturities by Contractual Maturities) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available For Sale Securities Debt Maturities Amortized Cost
Due in one year or less	$ 910,821
Due after one year through five years	7,339,134
Due after five year through ten years	9,581,912
Due after ten years	11,438,508
Asset and mortgage-backed securities	4,619,593
Total	33,889,968	$ 30,211,787
Available For Sale Securities Debt Maturities Fair Value
Due in one year or less	915,586
Due after one year through five years	7,618,692
Due after five year through ten years	10,090,704
Due after ten years	13,069,565
Asset and mortgage-backed securities	4,687,195
Total	$ 36,381,742	$ 32,093,625

Investments (Amortized Cost a42

Investments (Amortized Cost and Fair Value of Fixed Maturity Holdings by Industry Type) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 21,418,741	$ 18,924,711
Estimated Fair Value	$ 22,535,830	$ 19,619,084
% of Total	100.00%	100.00%
Financial Services Sector [Member]
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 7,797,576	$ 6,725,199
Estimated Fair Value	$ 8,146,891	$ 6,888,968
% of Total	36.20%	35.20%
Commercial and Industrial Sector [Member]
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 11,323,024	$ 10,228,813
Estimated Fair Value	$ 11,914,845	$ 10,639,613
% of Total	52.80%	54.20%
Utility Sector [Member]
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 2,298,141	$ 1,970,699
Estimated Fair Value	$ 2,474,094	$ 2,090,503
% of Total	11.00%	10.60%

Investments (Credit Losses Reco

Investments (Credit Losses Recognized in Earnings on Fixed Maturity Securities Held by the Company) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance, beginning of period	$ 3,677	$ 6,974	$ 6,013	$ 7,284
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Change in Status	0	0	(2,336)	(310)
Balance, end of period	$ 3,677	$ 6,974	$ 3,677	$ 6,974

Investments (Fair Value Below A

Investments (Fair Value Below Amortized Cost of Gross Unrealized Losses for Fixed Maturity and Equity Securities) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 163,210	$ 374,857
% of Total	100.00%	100.00%
Less than 20%
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 140,313	$ 337,831
% of Total	86.00%	90.10%
20% or more for less than six months
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 3,407	$ 19,438
% of Total	2.10%	5.20%
20% or more for six months or greater
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 19,490	$ 17,588
% of Total	11.90%	4.70%

Investments (Fair Value and Los

Investments (Fair Value and Losses by Investment Category and Length of Time in a Loss Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	$ 5,317,458	$ 8,327,843
Gross Unrealized Losses - Less than 12 months	64,798	253,005
Estimated Fair Value - 12 months or greater	1,949,631	1,210,148
Gross Unrealized Losses - 12 months or greater	94,006	108,194
Estimated Fair Value	7,267,089	9,537,991
Gross Unrealized Losses	158,804	361,199
Equity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	13,158	212,899
Gross Unrealized Losses - Less than 12 months	741	7,851
Estimated Fair Value - 12 months or greater	84,189	28,630
Gross Unrealized Losses - 12 months or greater	3,665	5,807
Estimated Fair Value	97,347	241,529
Gross Unrealized Losses	4,406	13,658
Non-investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	182,161	374,831
Gross Unrealized Losses - Less than 12 months	3,945	10,607
Estimated Fair Value - 12 months or greater	116,460	215,908
Gross Unrealized Losses - 12 months or greater	24,542	45,409
Estimated Fair Value	298,621	590,739
Gross Unrealized Losses	28,487	56,016
Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	5,135,297	7,953,012
Gross Unrealized Losses - Less than 12 months	60,853	242,398
Estimated Fair Value - 12 months or greater	1,833,171	994,240
Gross Unrealized Losses - 12 months or greater	69,464	62,785
Estimated Fair Value	6,968,468	8,947,252
Gross Unrealized Losses	130,317	305,183
Corporate Debt Securities [Member] | Non-investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	170,023	330,757
Gross Unrealized Losses - Less than 12 months	3,780	7,914
Estimated Fair Value - 12 months or greater	95,089	163,152
Gross Unrealized Losses - 12 months or greater	23,785	41,605
Estimated Fair Value	265,112	493,909
Gross Unrealized Losses	27,565	49,519
Corporate Debt Securities [Member] | Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	2,035,856	4,661,706
Gross Unrealized Losses - Less than 12 months	15,923	124,444
Estimated Fair Value - 12 months or greater	1,213,026	549,273
Gross Unrealized Losses - 12 months or greater	49,422	43,282
Estimated Fair Value	3,248,882	5,210,979
Gross Unrealized Losses	65,345	167,726
Canadian and Canadian provincial governments | Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	97,100	101,578
Gross Unrealized Losses - Less than 12 months	1,320	3,541
Estimated Fair Value - 12 months or greater	46,663	0
Gross Unrealized Losses - 12 months or greater	1,112	0
Estimated Fair Value	143,763	101,578
Gross Unrealized Losses	2,432	3,541
Residential mortgage-backed securities | Non-investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	0	0
Gross Unrealized Losses - Less than 12 months	0	0
Estimated Fair Value - 12 months or greater	93	412
Gross Unrealized Losses - 12 months or greater	3	12
Estimated Fair Value	93	412
Gross Unrealized Losses	3	12
Residential mortgage-backed securities | Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	507,372	490,473
Gross Unrealized Losses - Less than 12 months	5,084	9,733
Estimated Fair Value - 12 months or greater	154,469	112,216
Gross Unrealized Losses - 12 months or greater	3,189	3,635
Estimated Fair Value	661,841	602,689
Gross Unrealized Losses	8,273	13,368
Asset-backed securities | Non-investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	0	5,904
Gross Unrealized Losses - Less than 12 months	0	700
Estimated Fair Value - 12 months or greater	5,611	12,581
Gross Unrealized Losses - 12 months or greater	532	1,465
Estimated Fair Value	5,611	18,485
Gross Unrealized Losses	532	2,165
Asset-backed securities | Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	516,613	563,259
Gross Unrealized Losses - Less than 12 months	2,318	12,010
Estimated Fair Value - 12 months or greater	133,848	257,166
Gross Unrealized Losses - 12 months or greater	2,213	9,653
Estimated Fair Value	650,461	820,425
Gross Unrealized Losses	4,531	21,663
Commercial mortgage-backed securities | Non-investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months		5,815
Gross Unrealized Losses - Less than 12 months		735
Estimated Fair Value - 12 months or greater		0
Gross Unrealized Losses - 12 months or greater		0
Estimated Fair Value		5,815
Gross Unrealized Losses		735
Commercial mortgage-backed securities | Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	293,834	368,465
Gross Unrealized Losses - Less than 12 months	3,224	6,858
Estimated Fair Value - 12 months or greater	61,707	10,853
Gross Unrealized Losses - 12 months or greater	2,221	166
Estimated Fair Value	355,541	379,318
Gross Unrealized Losses	5,445	7,024
US Government Agencies Debt Securities [Member] | Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	1,302,732	1,056,101
Gross Unrealized Losses - Less than 12 months	29,712	63,044
Estimated Fair Value - 12 months or greater	56,595	0
Gross Unrealized Losses - 12 months or greater	1,286	0
Estimated Fair Value	1,359,327	1,056,101
Gross Unrealized Losses	30,998	63,044
US States and Political Subdivisions Debt Securities [Member] | Non-investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	919
Gross Unrealized Losses - Less than 12 months	88
Estimated Fair Value - 12 months or greater	0
Gross Unrealized Losses - 12 months or greater	0
Estimated Fair Value	919
Gross Unrealized Losses	88
US States and Political Subdivisions Debt Securities [Member] | Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	53,977	187,194
Gross Unrealized Losses - Less than 12 months	743	9,396
Estimated Fair Value - 12 months or greater	62,530	13,635
Gross Unrealized Losses - 12 months or greater	5,156	3,068
Estimated Fair Value	116,507	200,829
Gross Unrealized Losses	5,899	12,464
Foreign Government Debt Securities [Member] | Non-investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	11,219	32,355
Gross Unrealized Losses - Less than 12 months	77	1,258
Estimated Fair Value - 12 months or greater	15,667	39,763
Gross Unrealized Losses - 12 months or greater	222	2,327
Estimated Fair Value	26,886	72,118
Gross Unrealized Losses	299	3,585
Foreign Government Debt Securities [Member] | Investment grade securities | Fixed maturity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	327,813	524,236
Gross Unrealized Losses - Less than 12 months	2,529	13,372
Estimated Fair Value - 12 months or greater	104,333	51,097
Gross Unrealized Losses - 12 months or greater	4,865	2,981
Estimated Fair Value	432,146	575,333
Gross Unrealized Losses	7,394	16,353
Nonredeemable Preferred Stock [Member] | Equity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	6,712	10,831
Gross Unrealized Losses - Less than 12 months	345	831
Estimated Fair Value - 12 months or greater	25,983	21,879
Gross Unrealized Losses - 12 months or greater	2,944	5,506
Estimated Fair Value	32,695	32,710
Gross Unrealized Losses	3,289	6,337
Other equity securities | Equity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months	6,446	202,068
Gross Unrealized Losses - Less than 12 months	396	7,020
Estimated Fair Value - 12 months or greater	58,206	6,751
Gross Unrealized Losses - 12 months or greater	721	301
Estimated Fair Value	64,652	208,819
Gross Unrealized Losses	$ 1,117	$ 7,321

Investments (Investment Income

Investments (Investment Income Net of Related Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	$ 576,317	$ 507,781	$ 1,646,934	$ 1,468,130
Investment expense	(19,399)	(18,054)	(57,114)	(53,471)
Investment income, net of related expenses	556,918	489,727	1,589,820	1,414,659
Available-for-sale Securities [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	359,157	325,089	1,039,392	961,096
Mortgage Loans on Real Estate [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	50,040	39,802	138,829	121,494
Policy loans
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	15,404	15,391	45,870	47,897
Funds withheld at interest
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	102,144	104,609	327,089	273,482
Short-term Investments [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	1,977	1,752	5,266	6,265
Other invested assets
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	$ 47,595	$ 21,138	$ 90,488	$ 57,896

Investments (Investment Related

Investments (Investment Related Gains (Losses) Net) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Investment Gains And Losses [Abstract]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 390	$ 0	$ 20,980	$ 34,663
Impairment Losses On Equity Securities	(889)	0	(889)	0
Gain on investment activity	(19,522)	(46,346)	(91,635)	(127,153)
Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments	(7,678)	(9,054)	(30,712)	(43,397)
Other impairment losses and change in mortgage loan provision	(2,446)	(262)	(9,220)	(2,111)
Derivatives and other, net	14,534	49,594	109,637	37,020
Total investment related gains (losses), net	$ 22,653	$ 86,624	$ 139,471	$ 84,002

Investments (Borrowed Securitie

Investments (Borrowed Securities Repurchased Securities And Repurchased Reversed Repurchased Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Securities Loaned, Fair Value of Collateral	$ 121,958	$ 73,625
Securities Received as Collateral	120,000	80,000
Securities for Reverse Repurchase Agreements	491,824	476,531
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	522,354	515,200
Reported Value Measurement [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Borrowed	360,475	263,820
Securities Loaned, Fair Value of Collateral	117,219	74,389
Estimate of Fair Value Measurement [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Borrowed	379,101	279,186
Securities for Reverse Repurchase Agreements	$ 512,613	$ 499,891

Investments (Securities Pledged

Investments (Securities Pledged as Collateral Related to Repurchase Reverse Repurchase Program) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	$ 121,958	$ 73,625
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	512,613	499,891
Obligation to Return Securities Received as Collateral	634,571	573,516
Securities Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	680,850	624,032
SecuredBorrowingsGrossDifferenceAmount	46,279	50,516
Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	2,447
Obligation to Return Securities Received as Collateral	2,447	1,246
Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	1,472	0
Obligation to Return Securities Received as Collateral	1,472	0
Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	28,608	3,220
Obligation to Return Securities Received as Collateral	28,608	7,237
Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	480,086	495,425
Obligation to Return Securities Received as Collateral	602,044	565,033
Corporate Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	121,958	73,625
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	182,132	170,199
Corporate Debt Securities [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	0	0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Corporate Debt Securities [Member] | Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	0	0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	1,472	0
Corporate Debt Securities [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	0	4,017
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	5,402	3,220
Corporate Debt Securities [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	121,958	69,608
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	175,258	166,979
Residential Mortgage Backed Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	87,418	92,546
Residential Mortgage Backed Securities [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Residential Mortgage Backed Securities [Member] | Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Residential Mortgage Backed Securities [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Residential Mortgage Backed Securities [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	87,418	92,546
US Government Agencies Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement		216,000
US Government Agencies Debt Securities [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement		0
US Government Agencies Debt Securities [Member] | Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement		0
US Government Agencies Debt Securities [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement		0
US Government Agencies Debt Securities [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement		216,000
US Treasury and Government [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	219,246
US Treasury and Government [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0
US Treasury and Government [Member] | Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0
US Treasury and Government [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	23,206
US Treasury and Government [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	196,040
Foreign Government Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	21,370	19,900
Foreign Government Debt Securities [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Foreign Government Debt Securities [Member] | Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Foreign Government Debt Securities [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Foreign Government Debt Securities [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	21,370	19,900
Other Debt Obligations [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	2,447	1,246
Other Debt Obligations [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	2,447	1,246
Other Debt Obligations [Member] | Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Other Debt Obligations [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Other Debt Obligations [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	$ 0	$ 0

Investments (Mortgage Loans by

Investments (Mortgage Loans by Property Type) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 4,333,997		$ 3,783,207
Percentage of total	100.00%		100.00%
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ (2,531)		$ 0
Allowance for Loan and Lease Losses, Real Estate	(9,137)	$ (8,156)	(7,685)	$ (6,746)	$ (6,499)	$ (6,813)
Mortgage loans on real estate (net of allowances of $9,137 and $7,685)	4,322,329		3,775,522
Apartment
Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 508,367		$ 447,088
Percentage of total	11.70%		11.80%
Retail
Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 1,316,463		$ 1,179,936
Percentage of total	30.40%		31.20%
Office building
Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 1,426,673		$ 1,270,113
Percentage of total	32.90%		33.60%
Industrial
Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 891,051		$ 713,461
Percentage of total	20.60%		18.80%
Other commercial
Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 191,443		$ 172,609
Percentage of total	4.40%		4.60%

Investments (Mortgage Loans b51

Investments (Mortgage Loans by Maturity Date) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 4,333,997	$ 3,783,207
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
Due within five years
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 1,086,700	$ 822,073
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	25.10%	21.70%
Due after five years through ten years
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 2,334,113	$ 2,099,559
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	53.80%	55.50%
Due after ten years
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 913,184	$ 861,575
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	21.10%	22.80%

Investments (Mortgage Loans b52

Investments (Mortgage Loans by Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 4,333,997	$ 3,783,207
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
LTV 0 to 59 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 2,116,137	$ 1,925,755
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	48.80%	50.80%
LTV 60 To 69 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 1,646,440	$ 1,292,466
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	38.00%	34.20%
LTV 70 To 79 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 476,709	$ 415,330
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	11.00%	11.00%
LTV 80 to 100 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 94,711	$ 149,656
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	2.20%	4.00%
Debt Service Coverage Ratio Range One [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 4,051,289	$ 3,601,817
Debt Service Coverage Ratio Range One [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	2,060,277	1,859,640
Debt Service Coverage Ratio Range One [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	1,515,469	1,257,788
Debt Service Coverage Ratio Range One [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	424,195	370,092
Debt Service Coverage Ratio Range One [Member] | LTV 80 to 100 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	51,348	114,297
Debt Service Coverage Ratio Range Two [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	190,390	120,296
Debt Service Coverage Ratio Range Two [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	51,162	64,749
Debt Service Coverage Ratio Range Two [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	86,613	34,678
Debt Service Coverage Ratio Range Two [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	32,664	20,869
Debt Service Coverage Ratio Range Two [Member] | LTV 80 to 100 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	19,951	0
Debt Service Coverage Ratio Range Three [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	92,318	61,094
Debt Service Coverage Ratio Range Three [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	4,698	1,366
Debt Service Coverage Ratio Range Three [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	44,358	0
Debt Service Coverage Ratio Range Three [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	19,850	24,369
Debt Service Coverage Ratio Range Three [Member] | LTV 80 to 100 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 23,412	$ 35,359

Investments (Mortgage Loans b53

Investments (Mortgage Loans by Method of Evaluation and Related Valuation Allowances) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Mortgage Loans:
Total mortgage loans	$ 4,333,997	$ 3,783,207
Mortgage Loans on Real Estate, Commercial and Consumer, Net, (Investment Based Operations Presentation) [Abstract]
Mortgage loans on real estate (net of valuation allowances)	4,322,329	3,775,522
Commercial Real Estate Portfolio Segment [Member]
Mortgage Loans:
Evaluated individually for credit losses	5,856	2,216
Evaluated collectively for credit losses	4,328,141	3,780,991
Total mortgage loans	4,333,997	3,783,207
Valuation Allowances:
Specific for credit losses	0	0
Non-specifically identified credit losses	9,137	7,685
Total valuation allowances	$ 9,137	$ 7,685

Investments (Loan Valuation All

Investments (Loan Valuation Allowance for Mortgage Loans) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Allowance For Loan And Lease Losses Roll Forward
Balance, Beginning of Period	$ 8,156	$ 6,499	$ 7,685	$ 6,813
Provision (release)	977	247	1,444	(67)
Allowance for Loan and Lease Losses, Foreign Currency Translation	4	0	8	0
Balance, End of Period	$ 9,137	$ 6,746	$ 9,137	$ 6,746

Investments (Impaired Mortgage

Investments (Impaired Mortgage Loans) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		$ 6,427		$ 6,427		$ 2,758
Recorded Investment		5,856		5,856		2,216
Related Allowance		0		0		0
Carrying Value		5,856		5,856		2,216
Average Investment	[1]	3,967	$ 6,953	3,062	$ 10,146
Interest Income		33	107	100	324
Impaired mortgage loans with valuation allowance recorded
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		0		0		0
Recorded Investment		0		0		0
Related Allowance		0		0		0
Carrying Value		0		0		0
Average Investment	[1]	0	0	0	5,459
Interest Income		0	0	0	0
Impaired mortgage loans with no valuation allowance recorded
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		6,427		6,427		2,758
Recorded Investment		5,856		5,856		2,216
Related Allowance		0		0		0
Carrying Value		5,856		5,856		$ 2,216
Average Investment	[1]	3,967	6,953	3,062	4,687
Interest Income		$ 33	$ 107	$ 100	$ 324
[1]	Average recorded investment represents the average loan balances as of the beginning of period and all subsequent quarterly end of period balances.

Investments (Other Invested Ass

Investments (Other Invested Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Other invested assets	$ 1,532,523	$ 1,591,940
Equity securities
Other invested assets	112,931	275,361
Limited Partner [Member]
Other invested assets	761,739	687,522
Derivatives
Other invested assets	133,405	229,108
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Other invested assets	210,660	190,120
Other
Other invested assets	$ 313,788	$ 209,829

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)securities	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)securities	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)securities
Investment Narrative [Line Items]
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash	$ 38,500		$ 38,500		$ 28,800
Net Amount Assets Liabilities From Repurchase Reverse Repurchase Agreements	7,900		7,900		$ 5,500
Proceeds From Sale Of Available For Sale Securities Sold At Loss	484,700	$ 317,300	1,771,400	$ 903,100
Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments	$ 7,678	$ 9,054	$ 30,712	$ 43,397
Policy Loans Percent Of Total Investments	2.70%		2.70%		3.20%
Mortgage Loan Percent Of Cash And Invested Assets	8.70%		8.70%		8.40%
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities	1,165		1,165		1,535
Securities As Percentage Of Consolidated Stockholder Equity	10.00%		10.00%
Securities Borrowed Or Pledged, Minimum Fair Value Percentage			100.00%
Collateral Obtained Percent Of Fair Value Reverse Repurchase Agreements			100.00%
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%		100.00%		100.00%
Funds Withheld At Interest Percent Of Total Investments	12.10%		12.10%		13.10%
Funds withheld at interest	$ 6,020,336		$ 6,020,336		$ 5,875,919
Funds Held Under Reinsurance Agreements Asset Specific Client	$ 4,000,000		$ 4,000,000
Other Invested Assets Percent Of Cash And Invested Assets	3.10%		3.10%		3.60%
CALIFORNIA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	21.20%		21.20%		22.10%

Derivative Instruments (Gross N

Derivative Instruments (Gross Notional Amount and Fair Value of Derivatives Contracts) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Notional Amount	$ 14,700,117	$ 14,012,598
Carrying Value / Fair Value of Assets	284,281	283,094
Derivative Liability, Fair Value, Gross Liability	1,040,570	1,061,408
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	13,137,493	12,649,093
Carrying Value / Fair Value of Assets	211,831	150,834
Derivative Liability, Fair Value, Gross Liability	994,358	1,029,451
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	946,726	949,556
Carrying Value / Fair Value of Assets	61,263	78,405
Derivative Liability, Fair Value, Gross Liability	1,825	5,949
Not Designated as Hedging Instrument | Financial Futures
Derivative [Line Items]
Notional Amount	448,600	475,968
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument | Foreign Currency Forwards
Derivative [Line Items]
Notional Amount	6,000	25,000
Carrying Value / Fair Value of Assets	(84)	0
Derivative Liability, Fair Value, Gross Liability	0	5,070
Not Designated as Hedging Instrument | Consumer Price Index Swap [Member]
Derivative [Line Items]
Notional Amount	132,081	20,615
Carrying Value / Fair Value of Assets	589	0
Derivative Liability, Fair Value, Gross Liability	420	262
Not Designated as Hedging Instrument | Credit Default Swaps
Derivative [Line Items]
Notional Amount	948,000	926,000
Carrying Value / Fair Value of Assets	7,905	12,012
Derivative Liability, Fair Value, Gross Liability	490	2,871
Not Designated as Hedging Instrument | Equity Options
Derivative [Line Items]
Notional Amount	541,532	525,894
Carrying Value / Fair Value of Assets	20,006	33,459
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument | Longevity Swap [Member]
Derivative [Line Items]
Notional Amount	945,120	841,360
Carrying Value / Fair Value of Assets	37,827	26,958
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument | Mortality Swap [Member]
Derivative [Line Items]
Notional Amount	50,000	50,000
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	1,683	2,462
Not Designated as Hedging Instrument | Embedded Derivatives In Modified Coinsurance Or Funds Withheld Arrangements
Derivative [Line Items]
Notional Amount	0	0
Carrying Value / Fair Value of Assets	84,325	0
Derivative Liability, Fair Value, Gross Liability	0	22,529
Not Designated as Hedging Instrument | Embedded Derivatives In Indexed Annuity [Member]
Derivative [Line Items]
Notional Amount	0	0
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	821,821	805,672
Not Designated as Hedging Instrument | Embedded Derivatives In Variable Annuity [Member]
Derivative [Line Items]
Notional Amount	0	0
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	168,119	184,636
Not Designated as Hedging Instrument | Synthetic Guaranteed Investment Contracts
Derivative [Line Items]
Notional Amount	9,119,434	8,834,700
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Designated As Hedging Instrument
Derivative [Line Items]
Notional Amount	1,562,624	1,363,505
Carrying Value / Fair Value of Assets	72,450	132,260
Derivative Liability, Fair Value, Gross Liability	46,212	31,957
Designated As Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	435,000	435,000
Carrying Value / Fair Value of Assets	0	27,901
Derivative Liability, Fair Value, Gross Liability	22,133	31,223
Designated As Hedging Instrument | Foreign Currency Forwards
Derivative [Line Items]
Notional Amount	331,135	0
Carrying Value / Fair Value of Assets	1,418	0
Derivative Liability, Fair Value, Gross Liability	10,203	0
Designated As Hedging Instrument | Currency Swap [Member]
Derivative [Line Items]
Notional Amount	796,489	928,505
Carrying Value / Fair Value of Assets	71,032	104,359
Derivative Liability, Fair Value, Gross Liability	$ 13,876	$ 734

Derivative Instruments (Derivat

Derivative Instruments (Derivative Instruments Offsetting Balance Sheet) (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Derivative Assets [Abstract]
Derivative Fair Value Of Free Standing Derivative Asset		$ 199,956	$ 283,094
Gross Amounts Offset in the Balance Sheet		(28,724)	(27,028)
Net Amounts Presented in the Balance Sheet		171,232	256,066
Derivative Asset, Fair Value of Collateral	[1]	(17,782)	(16,913)
Gross Amounts Not Offset in the Balance Sheet - Cash Collateral Pledged/Received	[2]	(174,120)	(254,498)
Net Amount		(20,670)	(15,345)
Derivative Liabilities [Abstract]
Derivative Fair Value Of Free Standing Derivative Liability		50,630	48,571
Gross Amounts Offset in the Balance Sheet		(28,724)	(27,028)
Net Amounts Presented in the Balance Sheet		21,906	21,543
Gross Amounts Not Offset in the Balance Sheet - Financial Instruments	[3]	(58,360)	(95,863)
Gross Amounts Not Offset in the Balance Sheet - Cash Collateral Pledged/Received	[4]	(30,771)	(1,441)
Net Amount		$ (67,225)	$ (75,761)
[1]	Consists of U.S. Treasury and government securities.
[2]	Included in cash and cash equivalents, with obligation to return cash collateral recorded in other liabilities.
[3]	Included in available-for-sale securities, primarily consists of U.S. Treasury and government agency securities.
[4]	Consists of receivable from counterparty, included in other assets.

Derivative Instruments Derivati

Derivative Instruments Derivative Instruments (Fair Value Hedge Attributable to Foreign Currency) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ 2,100	$ 3,205	$ 9,541	$ 5,317
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(2,100)	(3,205)	(9,541)	(5,317)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	$ 0	$ 0	$ 0	$ 0

Derivative Instruments (Current

Derivative Instruments (Current Period Cash Flow Hedges in AOCI (loss) before Taxes) (Details) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (347)	$ 40,597	$ (7,690)	$ 41,192	$ (347)	$ 40,597	$ 2,496	$ 29,397
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(6,889)	932			3,689	(10,866)
Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(271)	(221)			(704)	(387)
Gain (Loss) on Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (183)	$ (116)			$ (142)	$ 53

Derivative Instruments (Cash Fl

Derivative Instruments (Cash Flow Hedges) (Details) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ (6,889)	$ 932			$ 3,689	$ (10,866)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	347	(40,597)	$ 7,690	$ (41,192)	347	(40,597)	$ (2,496)	$ (29,397)
Gain (Loss) on Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	183	116			142	(53)
Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	271	221			704	387
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(8,421)	(3,282)			(6,205)	(15,617)
Interest Rate Swap [Member] | Gain (Loss) on Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0			0	0
Interest Rate Swap [Member] | Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0			0	0
Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	1,544	4,214			9,894	4,751
Currency Swap [Member] | Gain (Loss) on Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0			0	0
Currency Swap [Member] | Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	230	200			560	454
Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(12)	0			0	0
Forward Contracts [Member] | Gain (Loss) on Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	183	116			142	(53)
Forward Contracts [Member] | Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 41	$ 21			$ 144	$ (67)

Derivative Instruments (Hedges

Derivative Instruments (Hedges of Net Investments in Foreign Operations) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	$ (30,571)	$ 8,341	$ (51,938)	$ (23,151)
Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	(35,198)	8,341	(60,723)	(23,151)
Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	$ 4,627	$ 0	$ 8,785	$ 0
[1]	There was no ineffectiveness recognized for the Company’s hedges of net investments in foreign operations.
[2]	There were no sales or substantial liquidations of net investments in foreign operations that would have required the reclassification of gains or losses from accumulated other comprehensive income (loss) into investment income during the periods presented.

Derivative Instruments (Non Hed

Derivative Instruments (Non Hedging Derivatives and Embedded Derivatives Effect on Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	$ 22,653	$ 86,624	$ 139,471	$ 84,002
Policy acquisition costs and other insurance expenses	(365,424)	(300,962)	(1,064,645)	(940,406)
Interest credited	(126,099)	(116,848)	(349,068)	(300,602)
Other revenues	75,942	72,468	218,091	197,844
Gain Loss On Investments Related To Change In Fair Value Of Derivatives Excluding Embedded Derivatives	(8,961)	(5,427)	(28,125)	89,408
Not Designated as Hedging Instrument
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(5,255)	31,535	59,757	19,384
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	641	4,122	12,318	108,149
Not Designated as Hedging Instrument | Financial Futures
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(8,890)	(11,677)	(28,107)	(30,285)
Not Designated as Hedging Instrument | Foreign Currency Forwards
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	24	507	577	6,584
Not Designated as Hedging Instrument | Consumer Price Index Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	220	76	211	(624)
Not Designated as Hedging Instrument | Credit Default Swaps
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	4,137	6,672	15,374	13,536
Not Designated as Hedging Instrument | Equity Options
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(8,295)	(13,648)	(34,757)	(19,576)
Not Designated as Hedging Instrument | Longevity Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Other revenues	3,334	8,921	7,180	11,402
Not Designated as Hedging Instrument | Mortality Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Other revenues	(132)	(400)	(921)	222
Not Designated as Hedging Instrument | Embedded Derivatives In Modified Coinsurance Or Funds Withheld Arrangements
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	23,044	49,078	106,854	33,795
Not Designated as Hedging Instrument | Embedded Derivatives In Indexed Annuity [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Interest credited	(13,133)	(20,104)	(35,490)	(20,730)
Not Designated as Hedging Instrument | Embedded Derivatives In Variable Annuity [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	$ (6,205)	$ 7,988	$ 16,518	$ (83,089)

Derivative Instruments (Exposur

Derivative Instruments (Exposure from Credit Derivatives by Rating of the Underlying Credits) (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 7,261	$ 8,970
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 944,700	$ 922,700
Derivative Average Remaining Maturity	[1],[3]	3 years 7 months	4 years 3 months
Standard Poors AAA To A Minus Ratings [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 2,975	$ 1,726
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 155,500	$ 150,500
Derivative Average Remaining Maturity	[1],[3]	3 years 2 months	3 years 10 months
Standard Poors AAA To A Minus Ratings [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 2,975	$ 1,726
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 155,500	$ 150,500
Derivative Average Remaining Maturity	[1],[3]	3 years 2 months	3 years 10 months
Standard Poors BBB Rating [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 4,209	$ 1,426
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 368,200	$ 347,200
Derivative Average Remaining Maturity	[1],[3]	3 years 2 months	3 years 8 months
Standard Poors BBB Rating [Member] | Credit Default Swaps Referencing Indices [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 56	$ 6,295
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 416,000	$ 416,000
Derivative Average Remaining Maturity	[1],[3]	4 years 2 months	5 years
Standard Poors BBB Rating [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 4,265	$ 7,721
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 784,200	$ 763,200
Derivative Average Remaining Maturity	[1],[3]	3 years 8 months	4 years 5 months
Standard & Poor's, BB Rating [Member]
Credit Derivatives [Line Items]
Derivative Average Remaining Maturity	[1],[2]	1 year 8 months	3 years 6 months
Standard & Poor's, BB Rating [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 21	$ (477)
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	5,000	9,000
Standard & Poor's, BB Rating [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	21	(477)
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 5,000	$ 9,000
[1]	The rating agency designations are based on ratings from Standard and Poor’s (“S&P”).
[2]	Assumes the value of the referenced credit obligations is zero.
[3]	The weighted average years to maturity of the credit default swaps is calculated based on weighted average notional amounts.

Derivative Instruments (Changes

Derivative Instruments (Changes in Estimated Fair Value Related to Embedded Derivatives) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Changes In Estimated Fair Value Related To Embedded Derivatives [Line Items]
Gain Loss On Investments Related To Change In Fair Value Of Derivatives Excluding Embedded Derivatives	$ (8,961)	$ (5,427)	$ (28,125)	$ 89,408
Embedded Derivatives In Modified Coinsurance Or Funds Withheld Arrangements
Changes In Estimated Fair Value Related To Embedded Derivatives [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	23,044	49,078	106,854	33,795
Derivative, Gain (Loss) on Derivative, Net	7,515	9,653	36,300	1,683
Embedded Derivatives In Equity Indexed Annuities [Member]
Changes In Estimated Fair Value Related To Embedded Derivatives [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(13,133)	(20,104)	(35,490)	(20,730)
Derivative, Gain (Loss) on Derivative, Net	(9,737)	(13,397)	(38,059)	(9,979)
Embedded Derivatives In Variable Annuity Contracts [Member]
Changes In Estimated Fair Value Related To Embedded Derivatives [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(6,205)	7,988	16,518	(83,089)
Derivative, Gain (Loss) on Derivative, Net	$ (1,074)	$ 2,595	$ 30,785	$ (63,415)

Derivative Instruments (Credit

Derivative Instruments (Credit Exposure of Derivative Contracts) (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Credit Exposure of Derivative Contracts
Estimated fair value of derivatives in net asset (liability) position		$ 151,009	$ 236,985
Derivative, Collateral, Right to Reclaim Cash	[1]	30,771	1,441
Derivative Liability, Fair Value of Collateral	[2]	58,360	95,863
Derivative, Collateral, Obligation to Return Cash	[3]	(174,120)	(254,498)
Derivative Asset, Fair Value of Collateral	[4]	(17,782)	(16,913)
Deposits with Clearing Organizations and Others, Securities	[2]	(58,360)	(73,571)
Net credit exposure		(10,122)	(10,693)
Margin account related to exchange-traded futures	[5]	$ 7,832	$ 9,687
[1]	Consists of receivable from counterparty, included in other assets.
[2]	Included in available-for-sale securities, primarily consists of U.S. Treasury and government agency securities.
[3]	Included in cash and cash equivalents, with obligation to return cash collateral recorded in other liabilities.
[4]	Consists of U.S. Treasury and government securities.
[5]	Included in other assets.

Derivative Instruments (Narrati

Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0.2		$ 0.8
Derivative Instruments, Gain Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing		$ 1.6		$ (5.4)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	(0.4)		(0.4)
Cumulative Foreign Currency Translation Gain Loss Recorded In Accumulated Other Comprehensive Income Loss For Terminated Net Investment In Foreign Operations Hedges	$ 109.7		$ 109.7		$ 161.6

Fair Value of Assets and Liab69

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Balances of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 36,381,742	$ 32,093,625
Funds withheld at interest embedded derivatives	84,325	(22,529)
Cash and cash equivalents	332,186	338,601
Short-term investments	56,454	44,241
Investments, Fair Value Disclosure	456,996	705,625
Other Assets, Fair Value Disclosure	37,827	26,958
Assets, Fair Value Disclosure, Recurring	37,349,530	33,186,521
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	989,940	990,308
Liabilities Fair Value Disclosure
Liabilities, Fair Value Disclosure, Recurring	1,011,846	1,011,851
Nonredeemable Preferred Stock [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	38,901	51,123
Other equity securities
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	74,030	224,238
Other
Assets Fair Value Disclosure
Investments, Fair Value Disclosure		11,036
Interest Rate Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	46,258	93,508
Liabilities Fair Value Disclosure
Other liabilities	8,953	24,374
Foreign Currency Forwards
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	1,418
Liabilities Fair Value Disclosure
Other liabilities	10,287	5,070
Consumer Price Index Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	230
Liabilities Fair Value Disclosure
Other liabilities	61	262
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	210,660	190,120
Credit Default Swaps
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	6,903	9,136
Liabilities Fair Value Disclosure
Other liabilities	512	5
Equity Option [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	9,700	26,070
Liabilities Fair Value Disclosure
Other liabilities	10,306	7,389
Currency Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	68,896	100,394
Liabilities Fair Value Disclosure
Other liabilities	11,740	3,231
Mortality Swap [Member]
Liabilities Fair Value Disclosure
Other liabilities	1,683	2,462
Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	22,535,830	19,619,084
Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,991,185	3,644,046
Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,679,305	1,278,576
Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,694,568	1,429,344
Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,313,322	1,363,654
US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,603,669	1,468,302
US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	661,031	591,796
Foreign Government Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	2,902,832	2,698,823
Fair Value Inputs Level 1 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	2,414,937	1,933,479
Funds withheld at interest embedded derivatives	0	0
Cash and cash equivalents	332,186	338,601
Short-term investments	0	8,276
Investments, Fair Value Disclosure	322,067	462,482
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure, Recurring	3,069,190	2,742,838
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	0	0
Liabilities Fair Value Disclosure
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value Inputs Level 1 Member | Nonredeemable Preferred Stock [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	38,901	38,317
Fair Value Inputs Level 1 Member | Other equity securities
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	74,030	224,238
Fair Value Inputs Level 1 Member | Other
Assets Fair Value Disclosure
Investments, Fair Value Disclosure		11,036
Fair Value Inputs Level 1 Member | Interest Rate Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 1 Member | Foreign Currency Forwards
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 1 Member | Consumer Price Index Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 1 Member | Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	209,136	188,891
Fair Value Inputs Level 1 Member | Credit Default Swaps
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 1 Member | Equity Option [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 1 Member | Currency Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 1 Member | Mortality Swap [Member]
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 1 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	615,433	310,995
Fair Value Inputs Level 1 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	0
Fair Value Inputs Level 1 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	0
Fair Value Inputs Level 1 Member | Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	0
Fair Value Inputs Level 1 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	0
Fair Value Inputs Level 1 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,480,357	1,345,755
Fair Value Inputs Level 1 Member | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	0
Fair Value Inputs Level 1 Member | Foreign Government Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	319,147	276,729
Fair Value Inputs Level 2 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	31,833,890	27,932,189
Funds withheld at interest embedded derivatives	0	0
Cash and cash equivalents	0	0
Short-term investments	53,095	32,619
Investments, Fair Value Disclosure	134,929	243,143
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure, Recurring	32,021,914	28,207,951
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	0	0
Liabilities Fair Value Disclosure
Liabilities, Fair Value Disclosure, Recurring	20,223	19,081
Fair Value Inputs Level 2 Member | Nonredeemable Preferred Stock [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	12,806
Fair Value Inputs Level 2 Member | Other equity securities
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Fair Value Inputs Level 2 Member | Other
Assets Fair Value Disclosure
Investments, Fair Value Disclosure		0
Fair Value Inputs Level 2 Member | Interest Rate Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	46,258	93,508
Liabilities Fair Value Disclosure
Other liabilities	8,953	24,374
Fair Value Inputs Level 2 Member | Foreign Currency Forwards
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	1,418
Liabilities Fair Value Disclosure
Other liabilities	10,287	5,070
Fair Value Inputs Level 2 Member | Consumer Price Index Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	230
Liabilities Fair Value Disclosure
Other liabilities	61	262
Fair Value Inputs Level 2 Member | Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	1,524	1,229
Fair Value Inputs Level 2 Member | Credit Default Swaps
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	6,903	9,136
Liabilities Fair Value Disclosure
Other liabilities	512	5
Fair Value Inputs Level 2 Member | Equity Option [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	9,700	26,070
Liabilities Fair Value Disclosure
Other liabilities	10,306	7,389
Fair Value Inputs Level 2 Member | Currency Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	68,896	100,394
Liabilities Fair Value Disclosure
Other liabilities	11,740	3,231
Fair Value Inputs Level 2 Member | Mortality Swap [Member]
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 2 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	20,648,377	18,035,836
Fair Value Inputs Level 2 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,465,820	3,168,081
Fair Value Inputs Level 2 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,561,310	1,118,285
Fair Value Inputs Level 2 Member | Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,549,371	1,210,064
Fair Value Inputs Level 2 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,311,375	1,342,509
Fair Value Inputs Level 2 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	100,061	98,059
Fair Value Inputs Level 2 Member | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	619,519	550,130
Fair Value Inputs Level 2 Member | Foreign Government Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	2,578,057	2,409,225
Fair Value Inputs Level 3 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	2,132,915	2,227,957
Funds withheld at interest embedded derivatives	84,325	(22,529)
Cash and cash equivalents	0	0
Short-term investments	3,359	3,346
Investments, Fair Value Disclosure	0	0
Other Assets, Fair Value Disclosure	37,827	26,958
Assets, Fair Value Disclosure, Recurring	2,258,426	2,235,732
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	989,940	990,308
Liabilities Fair Value Disclosure
Liabilities, Fair Value Disclosure, Recurring	991,623	992,770
Fair Value Inputs Level 3 Member | Nonredeemable Preferred Stock [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Fair Value Inputs Level 3 Member | Other equity securities
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Fair Value Inputs Level 3 Member | Other
Assets Fair Value Disclosure
Investments, Fair Value Disclosure		0
Fair Value Inputs Level 3 Member | Interest Rate Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 3 Member | Foreign Currency Forwards
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 3 Member | Consumer Price Index Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 3 Member | Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Fair Value Inputs Level 3 Member | Credit Default Swaps
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 3 Member | Equity Option [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 3 Member | Currency Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	0
Liabilities Fair Value Disclosure
Other liabilities	0	0
Fair Value Inputs Level 3 Member | Mortality Swap [Member]
Liabilities Fair Value Disclosure
Other liabilities	1,683	2,462
Fair Value Inputs Level 3 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,272,020	1,272,253
Fair Value Inputs Level 3 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	525,365	475,965
Fair Value Inputs Level 3 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	117,995	160,291
Fair Value Inputs Level 3 Member | Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	145,197	219,280
Fair Value Inputs Level 3 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,947	21,145
Fair Value Inputs Level 3 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	23,251	24,488
Fair Value Inputs Level 3 Member | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	41,512	41,666
Fair Value Inputs Level 3 Member | Foreign Government Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 5,628	$ 12,869

Fair Value of Assets and Liab70

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Quantitative Information for Level 3 Inputs) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Percentage Of Fixed Maturity Securities Classified As Level 3	5.90%	6.90%
Corporate Debt Securities [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 150,170	$ 167,815
Corporate Debt Securities [Member] | Weighted Average [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	1.00%	1.00%
Corporate Debt Securities [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	2.00%	2.00%
Corporate Debt Securities [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	0.00%	0.00%
Longevity Swap [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 37,827	$ 26,958
Longevity Swap [Member] | Weighted Average [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	2.00%	2.00%
Fair Value Inputs Mortality Improvement	3.00%	3.00%
Longevity Swap [Member] | Maximum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	100.00%	100.00%
Fair Value Inputs Mortality Improvement	10.00%	10.00%
Longevity Swap [Member] | Minimum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	0.00%	0.00%
Fair Value Inputs Mortality Improvement	(10.00%)	(10.00%)
US Government Agencies Debt Securities [Member] | Weighted Average [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	1.00%	1.00%
US Government Agencies Debt Securities [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	1.00%	1.00%
US Government Agencies Debt Securities [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	0.00%	0.00%
US States and Political Subdivisions Debt Securities [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 4,544	$ 4,670
US States and Political Subdivisions Debt Securities [Member] | Weighted Average [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	1.00%	1.00%
US States and Political Subdivisions Debt Securities [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	1.00%	1.00%
US States and Political Subdivisions Debt Securities [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount for Lack of Marketability	1.00%	1.00%
Embedded Derivatives In Indexed Annuity [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 821,821	$ 805,672
Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	10.00%	8.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	3.00%	2.00%
Fair Value Inputs Withdrawal	4.00%	3.00%
Fair Value Inputs Option Budget Projection	2.00%	2.00%
Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	35.00%	35.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	100.00%	100.00%
Fair Value Inputs Withdrawal	5.00%	5.00%
Fair Value Inputs Option Budget Projection	4.00%	4.00%
Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	0.00%	0.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	0.00%	0.00%
Fair Value Inputs Withdrawal	0.00%	0.00%
Fair Value Inputs Option Budget Projection	2.00%	2.00%
Embedded Derivatives In Variable Annuity [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 168,119	$ 184,636
Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	5.00%	6.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	1.00%	2.00%
Fair Value Inputs Withdrawal	3.00%	3.00%
Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	25.00%	25.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	100.00%	100.00%
Fair Value Inputs Withdrawal	7.00%	7.00%
Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	0.00%	0.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	0.00%	0.00%
Fair Value Inputs Withdrawal	0.00%	0.00%
Embedded Derivatives In Variable Annuity Contracts [Member] | Weighted Average [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Entity Credit Risk	1.00%	1.00%
Fair Value Assumptions, Expected Volatility Rate	9.00%	14.00%
Embedded Derivatives In Variable Annuity Contracts [Member] | Maximum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Entity Credit Risk	5.00%	5.00%
Fair Value Assumptions, Expected Volatility Rate	27.00%	27.00%
Embedded Derivatives In Variable Annuity Contracts [Member] | Minimum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Entity Credit Risk	0.00%	0.00%
Fair Value Assumptions, Expected Volatility Rate	0.00%	0.00%
Mortality Swap [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 1,683	$ 2,462
Mortality Swap [Member] | Weighted Average [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	1.00%	1.00%
Mortality Swap [Member] | Maximum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	100.00%	100.00%
Mortality Swap [Member] | Minimum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	0.00%	0.00%
Total Return Swap [Member] | Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 84,325	$ (22,529)
Total Return Swap [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	10.00%	8.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	3.00%	2.00%
Fair Value Inputs Withdrawal	4.00%	3.00%
Fair Value Inputs, Entity Credit Risk	1.00%	1.00%
Fair Value Inputs Credit Rate	3.00%	2.00%
Total Return Swap [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	35.00%	35.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	100.00%	100.00%
Fair Value Inputs Withdrawal	5.00%	5.00%
Fair Value Inputs, Entity Credit Risk	5.00%	5.00%
Fair Value Inputs Credit Rate	4.00%	4.00%
Total Return Swap [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate, Low End	0.00%	0.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Mortality Rate, Low End	0.00%	0.00%
Fair Value Inputs Withdrawal	0.00%	0.00%
Fair Value Inputs, Entity Credit Risk	0.00%	0.00%
Fair Value Inputs Credit Rate	2.00%	2.00%
Total Return Swap [Member] | US Government Agencies Debt Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 23,251	$ 24,488

Fair Value of Assets and Liab71

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Fair Value Assets Transfers between Level 1 and Level 2) (Details) - Corporate Debt Securities [Member] - Available-for-sale Securities [Member]	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Equity, Level 1 to Level 2 Transfers, Description	0	0
Fair Value, Equity, Level 2 to Level 1 Transfers, Description	0	88,674

Fair Value of Assets and Liab72

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
US Government Agencies Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, end of period		$ 23,251			$ 23,251
Foreign Government Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, end of period		5,628		$ 13,426	5,628		$ 13,426
Foreign Government Debt Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		61,281		(91,981)	(22,529)		(76,698)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0	0		0
Fair Value, end of period		84,325		(42,903)	84,325		(42,903)
Funds Withheld At Interest Embedded Derivatives [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Funds Withheld At Interest Embedded Derivatives [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		23,044		49,078	106,854		33,795
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		23,044		49,078	106,854		33,795
Funds Withheld At Interest Embedded Derivatives [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Funds Withheld At Interest Embedded Derivatives [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Longevity Swap [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		33,349		17,781	26,958		14,996
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		1,144		327	3,689		631
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	0	0	[1]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0	[1]	0	0	[1]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0	0		0
Fair Value, end of period		37,827		27,029	37,827		27,029
Longevity Swap [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Longevity Swap [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Longevity Swap [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Longevity Swap [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		3,334		8,921	7,180		11,402
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		3,334		8,921	7,180		11,402
Interest Sensitive Contract Liabilities Embedded Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3				0			0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		(974,631)		(1,125,380)	(990,308)		(1,070,584)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	[1]	(18,736)		(11,853)	(51,276)		(9,817)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	21,809		19,225	63,047		54,096
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0	0		0
Fair Value, end of period		(989,940)		(1,130,124)	(989,940)		(1,130,124)
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Investment Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings				0			0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Gain (Loss) on Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		10,047		(7,988)	(9,005)		83,089
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		11,900		(3,969)	(2,934)		92,842
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Interest Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		(8,335)		(20,104)	(20,408)		(20,730)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		30,145		39,329	83,456		74,826
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Other Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Mortality Swap [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales	[1]			0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3				0			0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		(1,552)		(1,997)	(2,462)		(2,619)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		1		0	1		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	0		329	1,700		329
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0	0		0
Fair Value, end of period		(1,683)		(2,068)	(1,683)		(2,068)
Mortality Swap [Member] | Investment Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings				0			0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Mortality Swap [Member] | Gain (Loss) on Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Mortality Swap [Member] | Interest Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Mortality Swap [Member] | Other Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		(132)		(400)	(922)		222
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(132)		(400)	(922)		222
Short-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		3,548			3,346
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(3)			1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(3,164)			(3,520)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(114)			(272)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		3,236			3,236
Fair Value, end of period		3,359			3,359
Short-term Investments [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0			0
Short-term Investments [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0			0
Short-term Investments [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0			0
Available-for-sale Securities [Member] | Corporate Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		1,291,054		1,297,382	1,272,253		1,226,970
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(2,700)		(19,635)	(2,300)		36,438
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(107,670)		(54,492)	(257,671)		(195,070)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(26,337)		(26,320)	(49,511)		(36,803)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(88,551)		(44,110)	(234,552)		(141,065)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		3,844		0	35,042		10,206
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(12,973)		23,255	12,973		28,987
Fair Value, end of period		1,272,020		1,255,904	1,272,020		1,255,904
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(383)		(567)	(1,202)		(1,986)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(394)		(489)	(1,213)		(1,917)
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		396		17,917	7,592		(3,939)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					(2,788)
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | Canadian Provincial Governments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		533,270		554,192	475,965		416,076
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(11,365)		16,342	39,669		148,407
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0	0		0
Fair Value, end of period		525,365		573,619	525,365		573,619
Available-for-sale Securities [Member] | Canadian Provincial Governments [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		3,460		3,085	9,731		9,136
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		3,460		3,085	9,731		9,136
Available-for-sale Securities [Member] | Canadian Provincial Governments [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					0
Available-for-sale Securities [Member] | Canadian Provincial Governments [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | Residential mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		148,685		165,979	160,291		330,649
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		104		2,597	2,716		2,104
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(26,765)		(27,548)	(72,582)		(99,776)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(3,553)		0	(18,624)		(167,684)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(3,645)		(6,935)	(15,084)		(31,839)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		15		1,544	5,515		1,544
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(50,390)		0	89,621		41,524
Fair Value, end of period		117,995		190,693	117,995		190,693
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(30)		(40)	(304)		(411)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(27)		(40)	(155)		2
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		44		0	524		(1,922)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					(346)
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		201,589		298,816	219,280		303,836
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(101)		3,410	6,802		(4,324)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		(5,013)	(45,215)		(102,063)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	0		0	0		38,681
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(15,243)		(18,602)	(60,966)		(26,523)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		36,994		28,285	75,752		53,081
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(78,202)		93,444	142,575		167,501
Fair Value, end of period		145,197		223,651	145,197		223,651
Available-for-sale Securities [Member] | Asset-backed securities | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		160		173	1,689		599
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		156		173	556		523
Available-for-sale Securities [Member] | Asset-backed securities | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		1,101
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					0
Available-for-sale Securities [Member] | Asset-backed securities | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		34,434		35,246	41,666		38,342
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(208)		553	(228)		1,725
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		(1,986)	0		(1,986)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]			0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(35)		(32)	(309)		(290)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		7,295		0	7,295		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0	6,844		4,205
Fair Value, end of period		41,512		37,763	41,512		37,763
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		26		10	(68)		205
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		26		10	(68)		205
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		23,567		26,255	24,488		26,265
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		6		(135)	269		922
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(134)		(147)	(370)		(404)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]			0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(340)		(312)	(1,528)		(1,391)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0	0		0
Fair Value, end of period		23,251		25,833	23,251		25,833
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(116)		(122)	(348)		(367)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(116)		(122)	(348)		(367)
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		11,994		13,706	12,869		14,065
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(7)		48	(210)		336
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(495)		0	(495)		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]			0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		(328)	(672)		(975)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(6,853)		0	6,853		0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(1)		0	(1)		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(1)		0	(1)		0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		1,943		37,935	21,145		68,563
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		5		(94)	(57)		(2,453)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	0		(1,545)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]			0	(3,720)		25,976
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(1)		(1)	(5,403)		(138)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		637	10,132		2,182
Fair Value, end of period		1,947		37,507	1,947		37,507
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		304	709		1,437
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		304	0		1,335
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				$ 0	(595)		(3,289)
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							$ 0
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					0
Available-for-sale Securities [Member] | US Treasury and Government [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0			$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		$ 0
[1]	The amount reported within purchases, sales and settlements is the purchase price (for purchases) and the sales/settlement proceeds (for sales and settlements) based upon the actual date purchased or sold/settled. Items purchased and sold/settled in the same period are excluded from the rollforward. The Company had no issuances during the period.

Fair Value of Assets and Liab73

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Fair Value Assets Measured on Non-Recurring Basis) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Mortgage Loans on Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets Carrying Value Prior To Impairment	[1]			$ 0	$ 6,913
Fair Value Assets Gains Losses	[1]	$ 0	$ 747	0	45
Partnership Interest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets Carrying Value Prior To Impairment	[2]			4,656	4,460
Fair Value Assets Gains Losses	[2]	(896)	0	(7,204)	(2,039)
Private Equity Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets Carrying Value Prior To Impairment	[3]			106	0
Fair Value Assets Gains Losses	[3]	$ (531)	$ 0	$ (531)	$ 0
[1]	Estimated fair values for impaired mortgage loans are based on internal valuation models using unobservable inputs or, if the loans are in foreclosure or are otherwise determined to be collateral dependent, are based on external appraisals of the underlying collateral
[2]	The impaired limited partnership interests presented above were accounted for using the cost method. Impairments on these cost method investments were recognized at estimated fair value determined using the net asset values of the Company’s ownership interest as provided in the financial statements of the investees. The market for these investments has limited activity and price transparency.
[3]	The fair value of the Company’s private equity investments is based on external valuation models.

Fair Value of Assets and Liab74

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Assets
Mortgage loans on real estate (net of valuation allowances)		$ 4,322,329	$ 3,775,522
Policy loans		1,340,146	1,427,602
Funds withheld at interest		6,020,336	5,875,919
Cash and cash equivalents		1,204,590	1,200,718	$ 1,379,693	$ 1,525,275
Short-term investments		80,582	76,710
Other invested assets		1,532,523	1,591,940
Accrued investment income		420,111	347,173
Liabilities
Interest-sensitive contract liabilities		16,370,090	14,029,354
Long-term debt		2,788,480	3,088,635
Collateral finance and securitization notes		796,825	840,700
Reported Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)		4,322,329	3,775,522
Policy loans		1,340,146	1,427,602
Funds withheld at interest	[1]	5,931,416	5,893,381
Cash and cash equivalents	[2]	872,404	862,117
Short-term investments	[2]	24,128	32,469
Other invested assets	[2]	601,905	477,132
Accrued investment income		420,111	347,173
Liabilities
Interest-sensitive contract liabilities	[1]	12,616,104	10,225,099
Long-term debt		2,778,480
Debt, Long-term and Short-term, Combined Amount			3,088,635
Collateral finance and securitization notes		796,825	840,700
Estimate of Fair Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)		4,494,964	3,786,987
Policy loans		1,340,146	1,427,602
Funds withheld at interest	[1]	6,309,369	6,193,166
Cash and cash equivalents	[2]	872,404	862,117
Short-term investments	[2]	24,128	32,469
Other invested assets	[2]	627,650	510,640
Accrued investment income		420,111	347,173
Liabilities
Interest-sensitive contract liabilities	[1]	12,960,161	10,234,544
Long-term Debt, Fair Value		2,997,791
Debt, Long-term and Short-term, Combined Amount			3,186,173
Collateral finance and securitization notes		708,342	745,805
Estimate of Fair Value Measurement [Member] | Net Asset Value [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)		0	0
Policy loans		0	0
Funds withheld at interest	[1]	0	0
Cash and cash equivalents	[2]	0	0
Short-term investments	[2]	0	0
Other invested assets	[2]	300,686	296,773
Accrued investment income		0	0
Liabilities
Interest-sensitive contract liabilities	[1]	0	0
Long-term Debt, Fair Value		0
Debt, Long-term and Short-term, Combined Amount			0
Collateral finance and securitization notes		0	0
Estimate of Fair Value Measurement [Member] | Fair Value Inputs Level 1 Member
Assets
Mortgage loans on real estate (net of valuation allowances)		0	0
Policy loans		0	0
Funds withheld at interest	[1]	0	0
Cash and cash equivalents	[2]	872,404	862,117
Short-term investments	[2]	24,128	32,469
Other invested assets	[2]	28,267	26,294
Accrued investment income		0	0
Liabilities
Interest-sensitive contract liabilities	[1]	0	0
Long-term Debt, Fair Value		0
Debt, Long-term and Short-term, Combined Amount			0
Collateral finance and securitization notes		0	0
Estimate of Fair Value Measurement [Member] | Fair Value Inputs Level 2 Member
Assets
Mortgage loans on real estate (net of valuation allowances)		0	0
Policy loans		1,340,146	1,427,602
Funds withheld at interest	[1]	0	0
Cash and cash equivalents	[2]	0	0
Short-term investments	[2]	0	0
Other invested assets	[2]	68,342	55,669
Accrued investment income		420,111	347,173
Liabilities
Interest-sensitive contract liabilities	[1]	0	0
Long-term Debt, Fair Value		0
Debt, Long-term and Short-term, Combined Amount			0
Collateral finance and securitization notes		0	0
Estimate of Fair Value Measurement [Member] | Fair Value Inputs Level 3 Member
Assets
Mortgage loans on real estate (net of valuation allowances)		4,494,964	3,786,987
Policy loans		0	0
Funds withheld at interest	[1]	6,309,369	6,193,166
Cash and cash equivalents	[2]	0	0
Short-term investments	[2]	0	0
Other invested assets	[2]	230,355	131,904
Accrued investment income		0	0
Liabilities
Interest-sensitive contract liabilities	[1]	12,960,161	10,234,544
Long-term Debt, Fair Value		2,997,791
Debt, Long-term and Short-term, Combined Amount			3,186,173
Collateral finance and securitization notes		$ 708,342	$ 745,805
[1]	Carrying values presented herein differ from those presented in the condensed consolidated balance sheets because certain items within the respective financial statement caption are embedded derivatives and are measured at fair value on a recurring basis.
[2]	Carrying values presented herein differ from those presented in the condensed consolidated balance sheets because certain items within the respective financial statement caption are measured at fair value on a recurring basis.

Fair Value of Assets and Liab75

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Narrative) (Details)	Sep. 30, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Percentage Of Fixed Maturity Securities Classified As Level 3	5.90%	6.90%

Segment Information (Total Reve

Segment Information (Total Revenues of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 3,145,310	$ 2,900,577	$ 9,283,326	$ 8,452,213
Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,785,553	1,721,052	5,367,576	4,959,854
CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	293,525	293,318	850,883	862,768
EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	438,013	388,822	1,255,413	1,128,831
Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	578,592	446,684	1,683,787	1,355,570
Corporate and Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	49,627	50,701	125,667	145,190
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,521,383	1,444,917	4,532,584	4,339,737
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	281,095	280,959	814,643	827,871
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	360,972	289,070	1,024,978	880,346
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	561,660	427,647	1,628,419	1,299,417
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	264,170	276,135	834,992	620,117
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	12,430	12,359	36,240	34,897
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	77,041	99,752	230,435	248,485
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 16,932	$ 19,037	$ 55,368	$ 56,153

Segment Information (Income Los

Segment Information (Income Loss Before Provision for Income Tax of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	$ 340,162	$ 287,600	$ 887,321	$ 748,403
Americas [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	249,630	179,795	580,755	436,281
CANADA
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	33,261	35,435	93,442	101,559
EMEA [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	46,374	52,301	132,527	110,912
Asia Pacific [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	26,335	27,371	132,594	111,493
Corporate and Other [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	(15,438)	(7,302)	(51,997)	(11,842)
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	160,512	77,081	281,066	239,609
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	28,789	34,275	80,953	97,679
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	15,421	8,515	40,751	14,233
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	26,564	19,822	121,574	95,464
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	89,118	102,714	299,689	196,672
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	4,472	1,160	12,489	3,880
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	30,953	43,786	91,776	96,679
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	$ (229)	$ 7,549	$ 11,020	$ 16,029

Segment Information (Total Asse

Segment Information (Total Assets of Reportable Segments) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 58,694,031	$ 53,097,879
Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	34,809,570	31,852,931
CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,265,734	3,932,087
EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	7,073,219	6,435,255
Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,938,166	4,644,362
Corporate and Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,607,342	6,233,244
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	18,707,824	18,140,825
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,177,125	3,846,682
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	2,978,701	2,559,124
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,750,652	3,968,081
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	16,101,746	13,712,106
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	88,609	85,405
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,094,518	3,876,131
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 1,187,514	$ 676,281

Commitments, Contingencies an79

Commitments, Contingencies and Guarantees (Commitments to Fund Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Limited Partner [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 349,157	$ 332,169
Commercial Loan [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	75,492	126,248
Bank Loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	51,479	58,318
Equity Release Mortgages [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 156,777	$ 130,324

Commitments, Contingencies an80

Commitments, Contingencies and Guarantees (Maximum Potential Obligation) (Details) $ in Millions	Sep. 30, 2017USD ($)
Commitment Period Two Thousand Twenty Three [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 500
Commitment Period Two Thousand Thirty Three [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	450
Commitment Period Two Thousand Thirty Four [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	2,000
Commitment Period Two Thousand Thirty Five [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	1,314.2
Commitment Period Two Thousand Thirty Six [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	2,932
Commitment Period Two Thousand Thirty Seven [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 5,750

Commitments, Contingencies an81

Commitments, Contingencies and Guarantees (Guarantees Issued) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Insurance Treaty Guarantee [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 936,032	$ 902,216
Insurance Treaty Guarantee Net Of Assets Held In Trust [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	810,870	780,786
Guarantee Of Borrowed Securities [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	295,285	263,820
Product Financing Arrangement [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	100,602	119,073
Guarantee Of Lease Obligations [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 1,895	$ 2,428

Income Tax (Provision for Incom

Income Tax (Provision for Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 119,057	$ 100,660	$ 310,562	$ 261,941
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	(3,635)	(2,335)	(14,049)	(14,617)
Income Tax Reconciliation Foreign Income Tax Basis Differential	2,126	(7,078)	(14,633)	(21,567)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	(2,501)	4,411	11,627	13,698
Effective Income Tax Rate Reconciliation, Tax Contingency, Domestic, Amount	299	(3,979)	(873)	(175)
Income Tax Reconciliation Change In Foreign Enacted Tax Rate	(1,139)	0	(2,332)	0
Income Tax Reconciliation SubpartF	64	1,779	1,390	3,212
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount	1,230	(1,934)	(834)	(2,655)
Effective Income Tax Rate Reconciliation, Equity in Earnings (Losses) of Unconsolidated Subsidiary, Amount	2,762	0	7,226	0
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount	452	(1,996)	133	(2,227)
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	(620)	(647)	(1,737)	(501)
Income Tax Expense (Benefit)	$ 112,571	$ 88,881	$ 282,028	$ 237,109
Effective Income Tax Rate Reconciliation, Percent	33.10%	30.90%	31.80%	31.70%

Employee Benefit Plans (Defined

Employee Benefit Plans (Defined Benefit Plans Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,699	$ 2,479	$ 8,098	$ 7,437
Interest cost	1,314	1,168	3,943	3,503
Expected return on plan assets	(1,554)	(1,285)	(4,662)	(3,854)
Amortization of prior service cost	85	76	254	229
Amortization of prior actuarial loss	1,081	1,040	3,244	3,121
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	256	0	769	0
Total	3,881	3,478	11,646	10,436
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	465	131	1,907	2,162
Interest cost	459	408	1,589	1,694
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(675)	(467)	(986)	(467)
Amortization of prior actuarial loss	580	137	1,494	1,370
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0	0
Total	$ 829	$ 209	$ 4,004	$ 4,759

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 5
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	10
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	$ 5

Reinsurance (Ceded Reinsurance

Reinsurance (Ceded Reinsurance Receivable Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 779,118	$ 683,972
Reinsurance Recoverables, Percentage of Total	100.00%	100.00%
Other Reinsurers [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 137,644	$ 118,679
Reinsurance Recoverables, Percentage of Total	17.70%	17.30%
AM Best, A+ Rating [Member] | Reinsurer A [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 291,115	$ 240,894
Reinsurance Recoverables, Percentage of Total	37.40%	35.20%
AM Best, A+ Rating [Member] | Reinsurer B [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 203,584	$ 183,881
Reinsurance Recoverables, Percentage of Total	26.10%	26.90%
AM Best, A+ Rating [Member] | Reinsurer C [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 65,528	$ 68,832
Reinsurance Recoverables, Percentage of Total	8.40%	10.10%
AM Best, A++ Rating [Member] | Reinsurer D [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 40,860	$ 36,202
Reinsurance Recoverables, Percentage of Total	5.20%	5.30%
AM Best, A Rating [Member] | Reinsurer E [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 40,387	$ 35,484
Reinsurance Recoverables, Percentage of Total	5.20%	5.20%

Reinsurance (Narrative) (Detail

Reinsurance (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Ceded Credit Risk [Line Items]
Reinsurance Claims Recoverables	$ 268.1	$ 242
Claims Recoverable From Retrocessionaires Past Due	$ 0.9	$ 4
AM Best, A- Rating [Member]
Ceded Credit Risk [Line Items]
Ceded Credit Risk, Disclosure	“A- (excellent)”	“A- (excellent)”

New Accounting Standards New Ac

New Accounting Standards New Accounting Standards (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounting Changes and Error Corrections [Abstract]
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle			$ 17,700
Effective Income Tax Rate Reconciliation, Equity in Earnings (Losses) of Unconsolidated Subsidiary, Amount	$ 2,762	$ 0	$ 7,226	$ 0