Reinsurance Group of America (RGA) 10-Q 3 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2018
Document And Entitiy Information [Abstract]
Document Type	10-Q
Document period end date	Jun. 30, 2018
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		63,656,444
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Fixed maturity securities available-for-sale, at fair value (amortized cost $35,233,970 and $35,281,412)	$ 36,784,954	$ 38,150,820
Equity Securities, FV-NI	108,070	100,152
Mortgage loans on real estate (net of allowances of $9,706 and $9,384)	4,558,669	4,400,533
Policy loans	1,339,252	1,357,624
Funds withheld at interest	5,981,092	6,083,388
Short-term investments	123,028	93,304
Other invested assets	1,605,562	1,505,332
Total investments	50,500,627	51,691,153
Cash and cash equivalents	1,397,679	1,303,524
Accrued investment income	400,160	392,721
Premiums receivable and other reinsurance balances	2,617,382	2,338,481
Reinsurance ceded receivables	789,429	782,027
Deferred policy acquisition costs	3,205,667	3,239,824
Other assets	855,553	767,088
Total assets	59,766,497	60,514,818
Liabilities and Stockholders’ Equity
Future policy benefits	22,286,622	22,363,241
Interest-sensitive contract liabilities	16,513,668	16,227,642
Other policy claims and benefits	5,334,210	4,992,074
Other reinsurance balances	412,846	488,739
Deferred income taxes	2,009,514	2,198,309
Other liabilities	1,094,826	1,102,975
Long-term debt	2,788,111	2,788,365
Collateral finance and securitization notes	724,998	783,938
Total liabilities	51,164,795	50,945,283
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 June 30, 2018 and December 31, 2017	791	791
Additional paid-in capital	1,887,336	1,870,906
Retained earnings	6,952,170	6,736,265
Treasury stock, at cost - 15,465,272 and 14,685,663 shares	(1,243,566)	(1,102,058)
Accumulated other comprehensive income	1,004,971	2,063,631
Total stockholders’ equity	8,601,702	9,569,535
Total liabilities and stockholders’ equity	$ 59,766,497	$ 60,514,818

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS PARENTHETICAL - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Available for Sale at Fair value - Amortized cost	$ 35,233,970	$ 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	63,672,486	64,452,095
Treasury stock, shares	15,465,272	14,685,663
Allowances for Loan and Lease Losses, Real Estate	$ 9,706	$ 9,384

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Net premiums	$ 2,594,460	$ 2,480,451	$ 5,177,011	$ 4,846,147
Investment income, net of related expenses	528,061	518,538	1,044,390	1,032,902
Investment related gains (losses), net:
Other-than-temporary impairments on fixed maturity securities	(3,350)	(3,401)	(3,350)	(20,590)
Other investment related gains (losses), net	(7,222)	59,696	(7,692)	137,408
Total investment related gains (losses), net	(10,572)	56,295	(11,042)	116,818
Other revenues	83,959	73,992	159,256	142,149
Total revenues	3,195,908	3,129,276	6,369,615	6,138,016
Benefits and Expenses:
Claims and other policy benefits	2,279,593	2,164,363	4,641,694	4,270,508
Interest credited	109,327	115,285	189,776	222,969
Policy acquisition costs and other insurance expenses	320,276	319,832	677,178	699,221
Other operating expenses	194,959	154,356	386,233	312,862
Interest expense	37,025	29,352	74,479	71,754
Collateral finance and securitization expense	7,440	6,773	15,042	13,543
Total benefits and expenses	2,948,620	2,789,961	5,984,402	5,590,857
Income before income taxes	247,288	339,315	385,213	547,159
Provision for income taxes	42,914	107,125	80,609	169,457
Net income	$ 204,374	$ 232,190	$ 304,604	$ 377,702
Earnings per share:
Basic earnings per share	$ 3.19	$ 3.60	$ 4.74	$ 5.86
Diluted earnings per share	3.13	3.54	4.65	5.76
Dividends declared per share	$ 0.50	$ 0.41	$ 1	$ 0.82

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Comprehensive income (loss)
Net income	$ 204,374	$ 232,190	$ 304,604	$ 377,702
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(54,677)	43,565	(55,837)	21,352
Net unrealized investment gains (losses)	(368,719)	306,329	(1,002,323)	509,444
Defined benefit pension and postretirement plan adjustments	(29)	849	(500)	1,773
Total other comprehensive income (loss), net of tax	(423,425)	350,743	(1,058,660)	532,569
Total comprehensive income (loss)	$ (219,051)	$ 582,933	$ (754,056)	$ 910,271

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 304,604	$ 377,702
Change in operating assets and liabilities:
Accrued investment income	1,834	(34,676)
Premiums receivable and other reinsurance balances	(345,253)	(230,650)
Deferred policy acquisition costs	20,528	35,870
Reinsurance ceded receivable balances	18,245	(127,995)
Future policy benefits, other policy claims and benefits, and other reinsurance balances	598,015	745,799
Deferred income taxes	48,117	142,044
Other assets and other liabilities, net	(98,807)	(63,811)
Amortization of net investment premiums, discounts and other	(25,713)	(47,563)
Depreciation, Depletion and Amortization	21,554	13,869
Investment related (gains) losses, net	11,042	(116,818)
Other, net	29,422	(37,797)
Net cash provided by operating activities	583,588	655,974
Cash Flows from Investing Activities:
Sales of fixed maturity securities available-for-sale	3,836,575	4,288,713
Maturities of fixed maturity securities available-for-sale	328,097	313,530
Proceeds from Sale of Available-for-sale Securities, Equity	29,099	166,916
Payments to Acquire Debt Securities, Available-for-sale	3,880,733	5,311,818
Payments to Acquire Available-for-sale Securities, Equity	(11,930)	(32,299)
Payments to Acquire Mortgage Notes Receivable	(376,470)	(463,063)
Proceeds from Sale and Collection of Mortgage Notes Receivable	213,691	135,450
Proceeds from Collection of Policy Loans	24,793	26,658
Payments for (Proceeds from) Policy Loans	6,421	5,830
Increase (Decrease) in Funds Held under Reinsurance Agreements	42,761	6,910
Payments to Acquire Businesses, Net of Cash Acquired	(29,315)	0
Payments to Acquire Property, Plant, and Equipment	(14,573)	31,686
Change in short-term investments	(9,843)	22,671
Change in other invested assets	(160,824)	(55,379)
Net cash used in investing activities	(100,615)	(889,675)
Cash Flows from Financing Activities:
Dividends to stockholders	(64,370)	(52,815)
Proceeds from (Repayments of) Secured Debt	(53,102)	(23,761)
Repayments of Long-term Debt	(1,331)	(301,278)
Purchases of treasury stock	(165,069)	(10,578)
Exercise of stock options, net	1,252	2,527
Change in cash collateral for derivative positions and other arrangements	17,578	(7,046)
Deposits on universal life and other investment type policies and contracts	225,876	917,675
Withdrawals on universal life and other investment type policies and contracts	(329,899)	(402,528)
Net cash (used in) provided by financing activities	(369,065)	122,196
Effect of exchange rate changes on cash	(19,753)	34,137
Change in cash and cash equivalents	94,155	(77,368)
Cash and cash equivalents, beginning of period	1,303,524	1,200,718
Cash and cash equivalents, end of period	1,397,679	1,123,350
Supplemental disclosures of cash flow information:
Interest Paid, Excluding Capitalized Interest, Operating Activities	84,670	90,425
Income Taxes Paid, Net	59,397	26,447
Transfer to Investments	604,374	2,243,360
Noncash or Part Noncash Acquisition, Value of Assets Acquired	65,948	0
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	$ 36,633	$ 0

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (PARENTHETICAL) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Statement of Cash Flows [Abstract]
Cash Acquired from Acquisition	$ 4,938

Business and Basis of Presentat

Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2018
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 six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 . 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 2017 Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on February 27, 2018 (the “2017 Annual Report”).

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2018
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 June 30, Six months ended June 30, 2018 2017 2018 2017 Earnings: Net income (numerator for basic and diluted calculations) $ 204,374 $ 232,190 $ 304,604 $ 377,702 Shares: Weighted average outstanding shares (denominator for basic calculation) 64,071 64,449 64,278 64,401 Equivalent shares from outstanding stock options 1,179 1,159 1,277 1,204 Denominator for diluted calculation 65,250 65,608 65,555 65,605 Earnings per share: Basic $ 3.19 $ 3.60 $ 4.74 $ 5.86 Diluted $ 3.13 $ 3.54 $ 4.65 $ 5.76 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. The following table presents approximate amounts of stock options and performance contingent shares excluded from the calculation of common equivalent shares (in millions): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Excluded from common equivalent shares: Stock options 0.2 0.2 0.3 0.3 Performance contingent shares 0.2 0.3 0.2 0.3

Equity

Equity	6 Months Ended
	Jun. 30, 2018
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, 2017 79,137,758 14,685,663 64,452,095 Common stock acquired — 991,477 (991,477 ) Stock-based compensation (1) — (211,868 ) 211,868 Balance, June 30, 2018 79,137,758 15,465,272 63,672,486 Issued Held In Treasury Outstanding Balance, December 31, 2016 79,137,758 14,835,256 64,302,502 Stock-based compensation (1) — (189,355 ) 189,355 Balance, June 30, 2017 79,137,758 14,645,901 64,491,857 (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. In January 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. During the first six months of 2018, RGA repurchased 1.0 million shares of common stock under this program for $150.0 million . During the first six months ended June 30, 2017, no common stock was repurchased by RGA under this program. Accumulated Other Comprehensive Income (Loss) The balance of and changes in each component of accumulated other comprehensive income (loss) (“AOCI”) for the six months ended June 30, 2018 and 2017 are as follows (dollars in thousands): Accumulated Currency Translation Adjustments Unrealized Appreciation (Depreciation) of Investments (1) Pension and Postretirement Benefits Total Balance, December 31, 2017 $ (86,350 ) $ 2,200,661 $ (50,680 ) $ 2,063,631 Other comprehensive income (loss) before reclassifications (44,227 ) (1,327,195 ) (2,986 ) (1,374,408 ) Amounts reclassified to (from) AOCI — 53,646 2,366 56,012 Deferred income tax benefit (expense) (11,610 ) 271,226 120 259,736 Balance, June 30, 2018 $ (142,187 ) $ 1,198,338 $ (51,180 ) $ 1,004,971 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 (13,936 ) 774,688 (196 ) 760,556 Amounts reclassified to (from) AOCI — (39,360 ) 2,935 (36,425 ) Deferred income tax benefit (expense) 35,288 (225,884 ) (966 ) (191,562 ) Balance, June 30, 2017 $ (151,189 ) $ 1,864,477 $ (41,390 ) $ 1,671,898 (1) Includes cash flow hedges of $22,656 and $2,619 as of June 30, 2018 and December 31, 2017 , respectively, and $1,131 and $(2,496) as of June 30, 2017 and December 31, 2016 , 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 six months ended June 30, 2018 and 2017 (dollars in thousands): Amount Reclassified from AOCI Three months ended June 30, Six months ended June 30, Details about AOCI Components 2018 2017 2018 2017 Affected Line Item in Statements of Income Net unrealized investment gains (losses): Net unrealized gains (losses) on available-for-sale securities $ (24,642 ) $ 40,374 $ (39,098 ) $ 28,517 Investment related gains (losses), net Cash flow hedges - Interest rate 29 — (342 ) — (1) Cash flow hedges - Currency/Interest rate 76 132 221 329 (1) Cash flow hedges - Forward bond purchase commitments — 51 — 101 (1) Deferred policy acquisition costs attributed to unrealized gains and losses (7,835 ) 4,565 (14,427 ) 10,413 (2) Total (32,372 ) 45,122 (53,646 ) 39,360 Provision for income taxes 6,945 (15,218 ) 11,623 (12,024 ) Net unrealized gains (losses), net of tax $ (25,427 ) $ 29,904 $ (42,023 ) $ 27,336 Amortization of defined benefit plan items: Prior service cost (credit) $ 247 $ 60 $ 493 $ 142 (3) Actuarial gains/(losses) (1,267 ) (1,539 ) (2,859 ) (3,077 ) (3) Total (1,020 ) (1,479 ) (2,366 ) (2,935 ) Provision for income taxes 214 517 497 1,027 Amortization of defined benefit plans, net of tax $ (806 ) $ (962 ) $ (1,869 ) $ (1,908 ) Total reclassifications for the period $ (26,233 ) $ 28,942 $ (43,892 ) $ 25,428 (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 2017 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	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Based Compensation	Equity Based Compensation Equity compensation expense was $16.6 million and $11.4 million in the first six months of 2018 and 2017 , respectively. In the first quarter of 2018, the Company granted 0.2 million stock appreciation rights at $150.87 weighted average exercise price per share and 0.1 million performance contingent units to employees. Additionally, non-employee directors were granted a total of 7,623 shares of common stock. As of June 30, 2018 , 1.5 million share options at a weighted average strike price per share of $65.70 were vested and exercisable, with a remaining weighted average exercise period of 4.4 years. As of June 30, 2018 , the total compensation cost of non-vested awards not yet recognized in the condensed consolidated financial statements was $36.9 million . It is estimated that these costs will vest over a weighted average period of 1.4 years.

Investments

Investments	6 Months Ended
	Jun. 30, 2018
Investments [Abstract]
Investments	Investments Fixed Maturity and Equity Securities Available-for-Sale The Company holds various types of fixed maturity securities available-for-sale and classifies them as corporate securities (“Corporate”), Canadian and Canadian provincial government securities (“Canadian government”), residential mortgage-backed securities (“RMBS”), asset-backed securities (“ABS”), commercial mortgage-backed securities (“CMBS”), U.S. government and agencies (“U.S. government”), state and political subdivisions, and other foreign government, supranational and foreign government-sponsored enterprises (“Other foreign government”). The following table provides information relating to investments in fixed maturity securities by sector as of June 30, 2018 (dollars in thousands): June 30, 2018: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate $ 22,249,964 $ 663,087 $ 409,544 $ 22,503,507 61.2 % $ — Canadian government 2,789,699 1,277,020 3,876 4,062,843 11.0 — RMBS 1,837,316 18,500 34,602 1,821,214 5.0 — ABS 1,711,099 11,596 13,871 1,708,824 4.6 275 CMBS 1,249,616 8,591 15,698 1,242,509 3.4 — U.S. government 1,583,622 8,193 66,665 1,525,150 4.1 — State and political subdivisions 703,047 43,318 9,321 737,044 2.0 — Other foreign government 3,109,607 112,887 38,631 3,183,863 8.7 — Total fixed maturity securities $ 35,233,970 $ 2,143,192 $ 592,208 $ 36,784,954 100.0 % $ 275 The following table provides information relating to investments in fixed maturity and equity securities by sector as of December 31, 2017 (dollars in thousands): December 31, 2017: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate $ 21,966,803 $ 1,299,594 $ 55,429 $ 23,210,968 60.9 % $ — Canadian government 2,843,273 1,378,510 1,707 4,220,076 11.1 — RMBS 1,695,126 36,632 11,878 1,719,880 4.5 — ABS 1,634,758 18,798 5,194 1,648,362 4.3 275 CMBS 1,285,594 22,627 4,834 1,303,387 3.4 — U.S. government 1,953,436 12,089 21,933 1,943,592 5.1 — State and political subdivisions 647,727 59,997 4,296 703,428 1.8 — Other foreign government 3,254,695 154,507 8,075 3,401,127 8.9 — Total fixed maturity securities $ 35,281,412 $ 2,982,754 $ 113,346 $ 38,150,820 100.0 % $ 275 Non-redeemable preferred stock $ 41,553 $ 479 $ 2,226 $ 39,806 39.7 % Other equity securities 61,288 479 1,421 60,346 60.3 Total equity securities $ 102,841 $ 958 $ 3,647 $ 100,152 100.0 % 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 June 30, 2018 and December 31, 2017 , none of the collateral received had been sold or repledged. The Company also holds assets in trust to satisfy collateral requirements under derivative transactions and 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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities pledged as collateral $ 63,640 $ 66,118 $ 72,542 $ 75,622 Fixed maturity securities received as collateral n/a 626,081 n/a 590,417 Assets in trust held to satisfy collateral requirements 16,061,218 16,571,173 15,584,296 16,715,281 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 June 30, 2018 and December 31, 2017 (dollars in thousands). June 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities guaranteed or issued by: Canadian province of Quebec $ 1,101,825 $ 1,850,642 $ 1,119,337 $ 1,917,996 Canadian province of Ontario 929,913 1,239,102 939,837 1,282,944 The amortized cost and estimated fair value of fixed maturity securities classified as available-for-sale at June 30, 2018 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 $ 978,683 $ 986,160 Due after one year through five years 7,550,595 7,649,023 Due after five years through ten years 9,208,763 9,323,786 Due after ten years 12,697,898 14,053,438 Asset and mortgage-backed securities 4,798,031 4,772,547 Total $ 35,233,970 $ 36,784,954 Corporate Fixed Maturity Securities The tables below show the major industry types of the Company’s corporate fixed maturity holdings as of June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018: Estimated Amortized Cost Fair Value % of Total Finance $ 8,097,947 $ 8,129,125 36.2 % Industrial 11,705,150 11,847,762 52.6 Utility 2,446,867 2,526,620 11.2 Total $ 22,249,964 $ 22,503,507 100.0 % December 31, 2017: Estimated Amortized Cost Fair Value % of Total Finance $ 7,977,885 $ 8,362,774 36.1 % Industrial 11,535,166 12,199,333 52.5 Utility 2,453,752 2,648,861 11.4 Total $ 21,966,803 $ 23,210,968 100.0 % Other-Than-Temporary Impairments - Fixed Maturity Securities As discussed in Note 2 – “Summary of Significant Accounting Policies” of the 2017 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 June 30, Six months ended June 30, 2018 2017 2018 2017 Balance, beginning of period $ 3,677 $ 3,677 $ 3,677 $ 6,013 Credit loss OTTI previously recognized on securities impaired to fair value during the period — — — (2,336 ) Balance, end of period $ 3,677 $ 3,677 $ 3,677 $ 3,677 Unrealized Losses for Fixed Maturity and Equity Securities Available-for-Sale The following table presents the total gross unrealized losses for the 2,580 fixed maturity securities as of June 30, 2018 , where the estimated fair value had declined and remained below amortized cost by the indicated amount (dollars in thousands): June 30, 2018 Gross Unrealized Losses % of Total Less than 20% $ 571,151 96.4 % 20% or more for less than six months 21,045 3.6 20% or more for six months or greater 12 — Total $ 592,208 100.0 % The following table presents the total gross unrealized losses for the 1,116 fixed maturity and equity securities at December 31, 2017 where the estimated fair value had declined and remained below amortized cost by the indicated amount (dollars in thousands): December 31, 2017 Gross % of Total Less than 20% $ 113,466 97.0 % 20% or more for less than six months 689 0.6 20% or more for six months or greater 2,838 2.4 Total $ 116,993 100.0 % 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. The following table presents the estimated fair values and gross unrealized losses, including other-than-temporary impairment losses reported in AOCI, for 2,580 fixed maturity securities that have estimated fair values below amortized cost as of June 30, 2018 (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 June 30, 2018: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate $ 9,135,620 $ 299,909 $ 818,555 $ 51,938 $ 9,954,175 $ 351,847 Canadian government 46,392 668 110,326 3,058 156,718 3,726 RMBS 1,101,941 25,546 241,914 9,032 1,343,855 34,578 ABS 807,714 10,637 139,676 3,187 947,390 13,824 CMBS 612,214 11,097 104,426 4,601 716,640 15,698 U.S. government 584,758 20,707 747,679 45,958 1,332,437 66,665 State and political subdivisions 168,817 5,064 66,122 4,257 234,939 9,321 Other foreign government 919,229 25,758 199,578 5,407 1,118,807 31,165 Total investment grade securities 13,376,685 399,386 2,428,276 127,438 15,804,961 526,824 Below investment grade securities: Corporate 735,338 47,846 56,042 9,851 791,380 57,697 Canadian government 1,864 150 — — 1,864 150 RMBS — — 1,194 24 1,194 24 ABS — — 1,148 47 1,148 47 Other foreign government 146,374 7,111 7,643 355 154,017 7,466 Total below investment grade securities 883,576 55,107 66,027 10,277 949,603 65,384 Total fixed maturity securities $ 14,260,261 $ 454,493 $ 2,494,303 $ 137,715 $ 16,754,564 $ 592,208 The following table presents the estimated fair values and gross unrealized losses, including other-than-temporary impairment losses reported in AOCI, for 1,116 fixed maturity and equity securities that have estimated fair values below amortized cost as of December 31, 2017 (dollars in thousands): Less than 12 months 12 months or greater Total Gross Gross Gross December 31, 2017: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate $ 1,886,212 $ 17,099 $ 1,009,750 $ 28,080 $ 2,895,962 $ 45,179 Canadian government 18,688 91 111,560 1,596 130,248 1,687 RMBS 566,699 5,852 224,439 6,004 791,138 11,856 ABS 434,274 2,707 168,524 2,434 602,798 5,141 CMBS 220,401 1,914 103,269 2,920 323,670 4,834 U.S. government 800,298 6,177 767,197 15,756 1,567,495 21,933 State and political subdivisions 43,510 242 68,666 4,054 112,176 4,296 Other foreign government 369,717 2,707 191,265 4,704 560,982 7,411 Total investment grade securities 4,339,799 36,789 2,644,670 65,548 6,984,469 102,337 Below investment grade securities: Corporate 194,879 3,317 75,731 6,933 270,610 10,250 Canadian government 1,995 20 — — 1,995 20 RMBS — — 1,369 22 1,369 22 ABS — — 1,489 53 1,489 53 Other foreign government 28,600 113 15,134 551 43,734 664 Total below investment grade securities 225,474 3,450 93,723 7,559 319,197 11,009 Total fixed maturity securities $ 4,565,273 $ 40,239 $ 2,738,393 $ 73,107 $ 7,303,666 $ 113,346 Non-redeemable preferred stock $ 82 $ 1 $ 26,471 $ 2,225 $ 26,553 $ 2,226 Other equity securities 5,820 1,023 47,251 398 53,071 1,421 Total equity securities $ 5,902 $ 1,024 $ 73,722 $ 2,623 $ 79,624 $ 3,647 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 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 June 30, 2018 are primarily related to publicly traded and privately placed corporate securities. Changes in unrealized losses are primarily being driven by changes in 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 June 30, Six months ended June 30, 2018 2017 2018 2017 Fixed maturity securities available-for-sale $ 373,624 $ 355,735 $ 742,827 $ 680,235 Equity securities 709 995 2,391 2,354 Mortgage loans on real estate 50,460 44,442 100,659 88,789 Policy loans 14,775 15,194 29,555 30,466 Funds withheld at interest 86,417 97,367 161,862 224,945 Short-term investments and cash and cash equivalents 2,964 1,779 6,209 3,289 Other invested assets 20,785 22,071 44,613 40,539 Investment income 549,734 537,583 1,088,116 1,070,617 Investment expense (21,673 ) (19,045 ) (43,726 ) (37,715 ) Investment income, net of related expenses $ 528,061 $ 518,538 $ 1,044,390 $ 1,032,902 Investment Related Gains (Losses), Net Investment related gains (losses), net consist of the following (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Fixed maturity securities available for sale: Other-than-temporary impairment losses $ (3,350 ) $ (3,401 ) $ (3,350 ) $ (20,590 ) Gain on investment activity 21,140 54,197 32,106 72,090 Loss on investment activity (35,934 ) (10,288 ) (56,314 ) (18,975 ) Equity securities: Gain on investment activity 469 23 497 23 Loss on investment activity — (183 ) (950 ) (4,059 ) Change in unrealized gains (losses) recognized in earnings (6,966 ) — (11,103 ) — Other impairment losses and change in mortgage loan provision (1,357 ) (6,675 ) (1,669 ) (6,774 ) Derivatives and other, net 15,426 22,622 29,741 95,103 Total investment related gains (losses), net $ (10,572 ) $ 56,295 $ (11,042 ) $ 116,818 The fixed maturity impairments for the three and six months ended June 30, 2018 and 2017 were largely related to high-yield corporate securities. The other impairment losses and change in mortgage loan provision for the three and six months ended June 30, 2018 includes impairments on real estate joint ventures. The other impairment losses and change in mortgage loan provision for the three and six months ended June 30, 2017 includes impairments on limited partnerships. The fluctuations in investment related gains (losses) for derivatives and other for the three and six months ended June 30, 2018 , compared to the same periods in 2017 , are primarily due to changes in the fair value of embedded derivatives and interest rate swaps. During the three months ended June 30, 2018 and 2017 , the Company sold fixed maturity securities with fair values of $1,174.4 million and $696.4 million at losses of $35.9 million and $10.3 million , respectively. During the six months ended June 30, 2018 and 2017 , the Company sold fixed maturity securities with fair values of $2,438.0 million and $1,125.0 million at losses of $56.3 million and $19.0 million , respectively. The Company did not sell any equity securities at losses during the three months ended June 30, 2018. During the three months ended June 30, 2017 , the Company sold equity securities with fair values of $14.1 million at losses of $0.2 million . During the six months ended June 30, 2018 and 2017 , the Company sold equity securities with fair values of $28.4 million and $161.7 million at losses of $1.0 million and $4.1 million , respectively. The Company generally does not buy and sell securities on a short-term basis. Securities Borrowing, Lending and Other 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 June 30, 2018 and December 31, 2017 (dollars in thousands). June 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Borrowed securities $ 350,350 $ 365,730 $ 358,875 $ 377,820 Securities lending: Securities loaned 101,995 102,208 117,246 121,551 Securities received n/a 112,000 n/a 128,000 Repurchase program/reverse repurchase program: Securities pledged 385,391 394,698 413,819 428,344 Securities received n/a 397,712 n/a 417,550 The Company also held cash collateral for securities lending and the repurchase program/reverse repurchase programs of $29.6 million and $31.2 million at June 30, 2018 and December 31, 2017 , respectively. No cash or securities have been pledged by the Company for its securities borrowing program as of June 30, 2018 and December 31, 2017 . The following tables present information on the Company’s securities lending and repurchase transactions as of June 30, 2018 and December 31, 2017 (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. June 30, 2018 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 $ — $ — $ — $ 102,208 $ 102,208 Total — — — 102,208 102,208 Repurchase transactions: Corporate — — — 151,519 151,519 U.S. government — — — 219,154 219,154 Foreign government — — — 22,894 22,894 Other 1,131 — — — 1,131 Total 1,131 — — 393,567 394,698 Total transactions $ 1,131 $ — $ — $ 495,775 $ 496,906 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 539,332 Amounts related to agreements not included in offsetting disclosure $ 42,426 December 31, 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 $ — $ — $ — $ 121,551 $ 121,551 Total $ — $ — $ — $ 121,551 $ 121,551 Repurchase transactions: Corporate $ — $ — $ 312 $ 184,334 $ 184,646 U.S. government — — — 220,765 220,765 Foreign government — — — 21,802 21,802 Other 1,131 — — — 1,131 Total 1,131 — 312 426,901 428,344 Total borrowings $ 1,131 $ — $ 312 $ 548,452 $ 549,895 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 576,786 Amounts related to agreements not included in offsetting disclosure $ 26,891 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 $0.4 million and $1.1 million of June 30, 2018 and December 31, 2017 , respectively. As of June 30, 2018 and December 31, 2017 , 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 9.0% and 8.5% of the Company’s total investments as of June 30, 2018 and December 31, 2017 . As of June 30, 2018 , mortgage loans were geographically dispersed throughout the U.S. with the largest concentrations in California ( 19.4% ), Texas ( 9.6% ) and Washington ( 7.8% ) and include loans secured by properties in Canada ( 2.6% ). 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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 Property type: Carrying Value % of Total Carrying Value % of Total Office building $ 1,546,148 33.9 % $ 1,487,392 33.6 % Retail 1,296,157 28.3 1,270,676 28.8 Industrial 962,049 21.0 938,612 21.3 Apartment 530,599 11.6 510,052 11.6 Other commercial 237,610 5.2 206,439 4.7 Recorded investment 4,572,563 100.0 % 4,413,171 100.0 % Unamortized balance of loan origination fees and expenses (4,188 ) (3,254 ) Valuation allowances (9,706 ) (9,384 ) Total mortgage loans on real estate $ 4,558,669 $ 4,400,533 The maturities of the mortgage loans as of June 30, 2018 and December 31, 2017 are as follows (dollars in thousands): June 30, 2018 December 31, 2017 Recorded Investment % of Total Recorded Investment % of Total Due within five years $ 1,153,623 25.2 % $ 1,091,066 24.8 % Due after five years through ten years 2,623,105 57.4 2,516,872 57.0 Due after ten years 795,835 17.4 805,233 18.2 Total $ 4,572,563 100.0 % $ 4,413,171 100.0 % The following tables set forth certain key credit quality indicators of the Company’s recorded investment in mortgage loans as of June 30, 2018 and December 31, 2017 (dollars in thousands): Recorded Investment Debt Service Ratios Construction loans >1.20x 1.00x - 1.20x <1.00x Total % of Total June 30, 2018: Loan-to-Value Ratio 0% - 59.99% $ 2,125,328 $ 102,254 $ 19,439 $ 17,602 $ 2,264,623 49.5 % 60% - 69.99% 1,552,568 117,751 49,221 — 1,719,540 37.6 70% - 79.99% 315,274 25,121 101,213 — 441,608 9.7 Greater than 80% 101,870 12,933 31,989 — 146,792 3.2 Total $ 4,095,040 $ 258,059 $ 201,862 $ 17,602 $ 4,572,563 100.0 % Recorded Investment Debt Service Ratios Construction loans >1.20x 1.00x - 1.20x <1.00x Total % of Total December 31, 2017: Loan-to-Value Ratio 0% - 59.99% $ 2,148,428 $ 53,979 $ 3,801 $ — $ 2,206,208 50.0 % 60% - 69.99% 1,517,029 47,128 43,921 — 1,608,078 36.4 70% - 79.99% 396,446 19,461 15,367 — 431,274 9.8 Greater than 80% 120,850 30,713 6,362 9,686 167,611 3.8 Total $ 4,182,753 $ 151,281 $ 69,451 $ 9,686 $ 4,413,171 100.0 % The age analysis of the Company’s past due recorded investments in mortgage loans as of June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 31-60 days past due $ 12,027 $ 17,100 61-90 days past due — 2,056 Total past due 12,027 19,156 Current 4,560,536 4,394,015 Total $ 4,572,563 $ 4,413,171 The following table presents the recorded investment in mortgage loans, by method of measuring impairment, and the related valuation allowances as of June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 Mortgage loans: Individually measured for impairment $ 30,653 $ 5,858 Collectively measured for impairment 4,541,910 4,407,313 Recorded investment $ 4,572,563 $ 4,413,171 Valuation allowances: Individually measured for impairment $ — $ — Collectively measured for impairment 9,706 9,384 Total valuation allowances $ 9,706 $ 9,384 Information regarding the Company’s loan valuation allowances for mortgage loans for the three and six months ended June 30, 2018 and 2017 is as follows (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Balance, beginning of period $ 8,864 $ 7,786 $ 9,384 $ 7,685 Provision (release) 845 366 329 467 Translation adjustment (3 ) 4 (7 ) 4 Balance, end of period $ 9,706 $ 8,156 $ 9,706 $ 8,156 Information regarding the portion of the Company’s mortgage loans that were impaired as of June 30, 2018 and December 31, 2017 is as follows (dollars in thousands): Unpaid Principal Balance Recorded Investment Related Allowance Carrying Value June 30, 2018: Impaired mortgage loans with no valuation allowance recorded $ 30,690 $ 30,653 $ — $ 30,653 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 30,690 $ 30,653 $ — $ 30,653 December 31, 2017: Impaired mortgage loans with no valuation allowance recorded $ 6,427 $ 5,858 $ — $ 5,858 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 6,427 $ 5,858 $ — $ 5,858 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 June 30, 2018 2017 Average (1) Interest Income Average Recorded Investment (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 27,038 $ 247 $ 2,088 $ 33 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 27,038 $ 247 $ 2,088 $ 33 Six months ended June 30, 2018 2017 Average (1) Interest Income Average (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 19,978 $ 304 $ 2,131 $ 67 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 19,978 $ 304 $ 2,131 $ 67 (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 six months ended June 30, 2018 and 2017 . The Company had no mortgage loans that were on a nonaccrual status at June 30, 2018 and December 31, 2017 . Policy Loans Policy loans comprised approximately 2.7% and 2.6% of the Company’s total investments as of June 30, 2018 and December 31, 2017 , 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 11.8% of the Company’s total investments as of both June 30, 2018 and December 31, 2017 . Of the $6.0 billion funds withheld at interest balance, net of embedded derivatives, as of June 30, 2018 , $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 limited partnership interests, joint ventures (other than operating joint ventures), equity release mortgages, 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 which is included in other in the table below. Other invested assets represented approximately 3.2% and 2.9% of the Company’s total investments as of June 30, 2018 and December 31, 2017 , respectively. Carrying values of these assets as of June 30, 2018 and December 31, 2017 are as follows (dollars in thousands): June 30, 2018 December 31, 2017 Limited partnership interests and real estate joint ventures $ 857,599 $ 781,124 Equity release mortgages 311,723 219,940 Derivatives 137,315 137,613 FVO contractholder-directed unit-linked investments 212,202 218,541 Other 86,723 148,114 Total other invested assets $ 1,605,562 $ 1,505,332

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 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 $ 1,084,555 $ 43,439 $ 2,514 $ 996,204 $ 59,809 $ 2,372 Financial futures 348,874 — — 412,438 — — Foreign currency forwards 4,512 — 8 6,030 — 28 Consumer price index swaps 328,190 1,126 199 221,932 — 2,160 Credit default swaps 928,300 6,725 122 961,200 8,319 1,651 Equity options 639,801 25,950 — 632,251 23,271 — Longevity swaps 934,720 43,971 — 960,400 40,659 — Mortality swaps 25,000 — 782 — — 1,683 Synthetic guaranteed investment contracts 10,634,677 — — 10,052,576 — — Embedded derivatives in: Modified coinsurance or funds withheld arrangements — 144,610 — — 122,194 — Indexed annuity products — — 806,436 — — 861,758 Variable annuity products — — 122,361 — — 152,470 Total non-hedging derivatives 14,928,629 265,821 932,422 14,243,031 254,252 1,022,122 Derivatives designated as hedging instruments: Interest rate swaps 435,000 204 19,699 435,000 — 20,389 Foreign currency swaps 580,036 58,294 2,598 672,921 65,207 8,496 Foreign currency forwards 718,177 18,428 — 553,175 1,265 7,720 Total hedging derivatives 1,733,213 76,926 22,297 1,661,096 66,472 36,605 Total derivatives $ 16,661,842 $ 342,747 $ 954,719 $ 15,904,127 $ 320,724 $ 1,058,727 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 June 30, 2018 and December 31, 2017 (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 June 30, 2018: Derivative assets $ 198,137 $ (16,851 ) $ 181,286 $ — $ (194,067 ) $ (12,781 ) Derivative liabilities 25,922 (16,851 ) 9,071 (57,302 ) (9,030 ) (57,261 ) December 31, 2017: Derivative assets $ 198,530 $ (20,258 ) $ 178,272 $ (862 ) $ (185,900 ) $ (8,490 ) Derivative liabilities 44,499 (20,258 ) 24,241 (58,156 ) (22,221 ) (56,136 ) (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 June 30, 2018 and December 31, 2017 , 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 2017 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 June 30, 2018 and 2017, were (dollars in thousands): Type of Fair Value Hedge Hedged Item Gains (Losses) Recognized for Derivatives (1) Gains (Losses) Recognized for Hedged Items (1) For the three months ended June 30, 2018: Foreign currency swaps Foreign-denominated fixed maturity securities $ (1,134 ) $ 4,942 For the three months ended June 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 905 $ (905 ) For the six months ended June 30, 2018: Foreign currency swaps Foreign-denominated fixed maturity securities $ (3,025 ) $ 6,833 For the six months ended June 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 7,441 $ (7,441 ) (1) The net amount represents the ineffective portion of the fair value hedges 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 six months ended June 30, 2018 and 2017 (dollars in thousands): Three months ended June 30, 2018 2017 Balance beginning of period $ 20,662 $ 7,690 Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges 2,099 (6,417 ) Amounts reclassified to investment related (gains) losses, net — 41 Amounts reclassified to investment income (76 ) (183 ) Amounts reclassified to interest expense (29 ) — Balance end of period $ 22,656 $ 1,131 Six months ended June 30, 2018 2017 Balance beginning of period $ 2,619 $ (2,496 ) Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges 19,916 4,016 Amounts reclassified to investment related (gains) losses, net — 41 Amounts reclassified to investment income (221 ) (430 ) Amounts reclassified to interest expense 342 — Balance end of period $ 22,656 $ 1,131 As of June 30, 2018 , 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 and $1.5 million in investment income and interest expense, respectively. 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 six months ended June 30, 2018 and 2017 (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 Interest Expense For the three months ended June 30, 2018: Interest rate $ 4,742 $ — $ — $ 29 Currency/Interest rate (2,643 ) — 76 — Total $ 2,099 $ — $ 76 $ 29 For the three months ended June 30, 2017: Interest rate $ (7,643 ) $ — $ — $ — Currency/Interest rate 1,226 — 132 — Forward bond purchase commitments — (41 ) 51 — Total $ (6,417 ) $ (41 ) $ 183 $ — For the six months ended June 30, 2018: Interest rate $ 19,727 $ — $ — $ (342 ) Currency/Interest rate 189 — 221 — Total $ 19,916 $ — $ 221 $ (342 ) For the six months ended June 30, 2017: Interest rate $ (5,427 ) $ — $ — $ — Currency/Interest rate 9,443 — 329 — Forward bond purchase commitments — (41 ) 101 — Total $ 4,016 $ (41 ) $ 430 $ — For the three and six months ended June 30, 2018 and 2017 , 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 six months ended June 30, 2018 and 2017 (dollars in thousands): Derivative Gains (Losses) Deferred in AOCI For the three months ended June 30, For the six months ended June 30, Type of NIFO Hedge (1) (2) 2018 2017 2018 2017 Foreign currency swaps $ 8,197 $ (17,919 ) $ 17,002 $ (25,525 ) Foreign currency forwards 11,063 4,158 23,299 4,158 Total $ 19,260 $ (13,761 ) $ 40,301 $ (21,367 ) (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 $154.0 million and $113.7 million at June 30, 2018 and December 31, 2017 , 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 six months ended June 30, 2018 and 2017 is as follows (dollars in thousands): Gain (Loss) for the three months ended June 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2018 2017 Interest rate swaps Investment related gains (losses), net $ (8,600 ) $ 14,289 Financial futures Investment related gains (losses), net (897 ) (6,442 ) Foreign currency forwards Investment related gains (losses), net (262 ) (351 ) CPI swaps Investment related gains (losses), net 1,041 (4 ) Credit default swaps Investment related gains (losses), net 1,084 3,879 Equity options Investment related gains (losses), net (8,007 ) (9,273 ) Longevity swaps Other revenues 2,289 1,981 Mortality swaps Other revenues (799 ) (395 ) Subtotal (14,151 ) 3,684 Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 8,805 15,108 Indexed annuity products Interest credited 6,519 (5,955 ) Variable annuity products Investment related gains (losses), net 15,324 360 Total non-hedging derivatives $ 16,497 $ 13,197 Gain (Loss) for the six months ended June 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2018 2017 Interest rate swaps Investment related gains (losses), net $ (35,171 ) $ 11,677 Financial futures Investment related gains (losses), net (768 ) (19,217 ) Foreign currency forwards Investment related gains (losses), net 61 553 CPI swaps Investment related gains (losses), net 3,227 (9 ) Credit default swaps Investment related gains (losses), net 682 11,237 Equity options Investment related gains (losses), net (5,414 ) (26,462 ) Longevity swaps Other revenues 4,557 3,847 Mortality swaps Other revenues (799 ) (790 ) Subtotal (33,625 ) (19,164 ) Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 22,416 83,810 Indexed annuity products Interest credited 31,870 (22,357 ) Variable annuity products Investment related gains (losses), net 30,109 22,723 Total non-hedging derivatives $ 50,770 $ 65,012 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. 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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 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 $ 2,574 $ 152,000 2.7 $ 3,128 $ 162,000 2.9 Subtotal 2,574 152,000 2.7 3,128 162,000 2.9 BBB+/BBB/BBB- Single name credit default swaps 4,092 338,700 2.6 4,469 361,700 2.9 Credit default swaps referencing indices (59 ) 422,600 3.5 (55 ) 422,600 4.0 Subtotal 4,033 761,300 3.1 4,414 784,300 3.5 BB+/BB/BB- Single name credit default swaps (4 ) 15,000 1.2 30 5,000 1.5 Subtotal (4 ) 15,000 1.2 30 5,000 1.5 Total $ 6,603 $ 928,300 3.0 $ 7,572 $ 951,300 3.4 (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 six months ended June 30, 2018 and 2017 . The related gains (losses) and the effect on net income after amortization of deferred acquisition costs (“DAC”) and income taxes for the three and six months ended June 30, 2018 and 2017 are reflected in the following table (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Embedded derivatives in modco or funds withheld arrangements included in investment related gains $ 8,805 $ 15,108 $ 22,416 $ 83,810 After the associated amortization of DAC and taxes, the related amounts included in net income 5,987 2,941 12,836 28,785 Embedded derivatives in variable annuity contracts included in investment related gains 15,324 360 30,109 22,723 After the associated amortization of DAC and taxes, the related amounts included in net income 12,472 3,023 23,598 31,859 Amounts related to embedded derivatives in equity-indexed annuities included in benefits and expenses 6,519 (5,955 ) 31,870 (22,357 ) After the associated amortization of DAC and taxes, the related amounts included in net income 3,966 (6,925 ) 10,503 (28,322 ) 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. In 2017, the Company followed the Chicago Mercantile Exchange amended rulebook to legally characterize variation margin payments as settlements of the derivative’s mark-to-market exposure and not collateral. 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 June 30, 2018 and December 31, 2017 are reflected in the following table (dollars in thousands): June 30, 2018 December 31, 2017 Estimated fair value of derivatives in net asset position $ 172,997 $ 155,714 Cash provided as collateral (1) 9,030 22,221 Securities pledged to counterparties as collateral (2) 57,302 58,156 Cash pledged from counterparties as collateral (3) (194,067 ) (185,900 ) Securities pledged from counterparties as collateral (4) — (862 ) Initial margin for cleared derivatives (2) (57,302 ) (58,156 ) Net amount after application of master netting agreements and collateral $ (12,040 ) $ (8,827 ) Margin account related to exchange-traded futures (5) $ 8,331 $ 6,538 (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	6 Months Ended
	Jun. 30, 2018
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. For a discussion of the Company’s valuation methodologies for assets and liabilities measured at fair value and the fair value hierarchy, see Note 6 in the Notes to Consolidated Financial Statements included in the Company’s 2017 Annual Report. Assets and Liabilities by Hierarchy Level Assets and liabilities measured at fair value on a recurring basis as of June 30, 2018 and December 31, 2017 are summarized below (dollars in thousands): June 30, 2018: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate $ 22,503,507 $ — $ 21,136,353 $ 1,367,154 Canadian government 4,062,843 — 3,490,145 572,698 RMBS 1,821,214 — 1,766,375 54,839 ABS 1,708,824 — 1,638,138 70,686 CMBS 1,242,509 — 1,240,642 1,867 U.S. government 1,525,150 1,405,485 98,930 20,735 State and political subdivisions 737,044 — 720,539 16,505 Other foreign government 3,183,863 — 3,178,819 5,044 Total fixed maturity securities – available-for-sale 36,784,954 1,405,485 33,269,941 2,109,528 Equity securities 108,070 65,133 — 42,937 Funds withheld at interest – embedded derivatives 144,610 — — 144,610 Cash equivalents 424,601 409,242 15,359 — Short-term investments 82,521 991 78,313 3,217 Other invested assets: Derivatives: Interest rate swaps 36,170 — 36,170 — Foreign currency forwards 18,428 — 18,428 — CPI swaps (42 ) — (42 ) — Credit default swaps 5,927 — 5,927 — Equity options 21,136 — 21,136 — Foreign currency swaps 55,696 — 55,696 — FVO contractholder-directed unit-linked investments 212,202 211,141 1,061 — Total other invested assets 349,517 211,141 138,376 — Other assets - longevity swaps 43,971 — — 43,971 Total $ 37,938,244 $ 2,091,992 $ 33,501,989 $ 2,344,263 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 928,797 $ — $ — $ 928,797 Other liabilities: Derivatives: Interest rate swaps 14,740 — 14,740 — Foreign currency forwards 8 — 8 — CPI swaps (969 ) — (969 ) — Credit default swaps (676 ) — (676 ) — Equity options (4,814 ) — (4,814 ) — Mortality swaps 782 — — 782 Total $ 937,868 $ — $ 8,289 $ 929,579 December 31, 2017: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate $ 23,210,968 $ — $ 21,873,696 $ 1,337,272 Canadian government 4,220,076 — 3,626,134 593,942 RMBS 1,719,880 — 1,611,998 107,882 ABS 1,648,362 — 1,524,888 123,474 CMBS 1,303,387 — 1,300,153 3,234 U.S. government 1,943,592 1,818,006 103,075 22,511 State and political subdivisions 703,428 — 662,225 41,203 Other foreign government 3,401,127 — 3,396,035 5,092 Total fixed maturity securities – available-for-sale 38,150,820 1,818,006 34,098,204 2,234,610 Equity securities: Non-redeemable preferred stock 39,806 39,806 — — Other equity securities 60,346 60,346 — — Funds withheld at interest – embedded derivatives 122,194 — — 122,194 Cash equivalents 356,788 354,071 2,717 — Short-term investments 50,746 — 47,650 3,096 Other invested assets: Derivatives: Interest rate swaps 51,359 — 51,359 — Foreign currency forwards 730 — 730 — CPI swaps (221 ) — (221 ) — Credit default swaps 5,908 — 5,908 — Equity options 16,932 — 16,932 — Foreign currency swaps 62,905 — 62,905 — FVO contractholder-directed unit-linked investments 218,541 217,618 923 — Total other invested assets 356,154 217,618 138,536 — Other assets - longevity swaps 40,659 — — 40,659 Total $ 39,177,513 $ 2,489,847 $ 34,287,107 $ 2,400,559 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 1,014,228 $ — $ — $ 1,014,228 Other liabilities: Derivatives: Interest rate swaps 14,311 — 14,311 — Foreign currency forwards 7,213 — 7,213 — CPI swaps 1,939 — 1,939 — Credit default swaps (760 ) — (760 ) — Equity options (6,339 ) — (6,339 ) — Foreign currency swaps 6,194 — 6,194 — Mortality swaps 1,683 — — 1,683 Total $ 1,038,469 $ — $ 22,558 $ 1,015,911 Transfers between Levels 1 and 2 Transfers between Levels 1 and 2 are made to reflect changes in observability of inputs and market activity. There were no transfers between Level 1 and Level 2 for the six months ended June 30, 2018. 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. The following tables present the transfers between Level 1 and Level 2 during the three and six months ended June 30, 2017 (dollars in thousands): 2017 Transfers from Level 1 to Level 2 Transfers from Level 2 to Level 1 Three months ended June 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ 49,999 Six months ended June 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ 88,674 Quantitative Information Regarding Internally - Priced Level 3 Assets and Liabilities 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 June 30, 2018 and December 31, 2017 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) June 30, 2018 December 31, 2017 June 30, 2018 December 31, 2017 Assets: Corporate $ 571,750 $ 173,579 Market comparable securities Liquidity premium 0-2% (1%) 0-2% (1%) EBITDA Multiple 5.9x-7.5x (6.9x) — U.S. government 20,735 22,511 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions 4,361 4,616 Market comparable securities Liquidity premium 1 % 1 % Other foreign government 5,044 — Market comparable securities Liquidity premium 1 % — Equity securities 23,856 — Market comparable securities Liquidity premium 1 % — EBITDA Multiple 6.9x-13.1x (7.9x) — Funds withheld at interest- embedded derivatives 144,610 122,194 Total return swap Mortality 0-100% (2%) 0-100% (2%) Lapse 0-35% (9%) 0-35% (9%) Withdrawal 0-5% (3%) 0-5% (3%) CVA 0-5% (1%) 0-5% (1%) Crediting rate 2-4% (2%) 2-4% (2%) Longevity swaps 43,971 40,659 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 806,436 861,758 Discounted cash flow Mortality 0-100% (2%) 0-100% (2%) Lapse 0-35% (9%) 0-35% (9%) Withdrawal 0-5% (3%) 0-5% (3%) Option budget projection 2-4% (2%) 2-4% (2%) Interest sensitive contract liabilities- embedded derivatives- variable annuities 122,361 152,470 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%) Lapse 0-25% (5%) 0-25% (5%) Withdrawal 0-7% (4%) 0-7% (3%) CVA 0-5% (1%) 0-5% (1%) Long-term volatility 0-27% (14%) 0-27% (8%) Mortality swaps 782 1,683 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%) Changes in Level 3 Assets and Liabilities 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. The Company also transferred equity securities with a fair value of approximately $38.9 million into Level 3 as a result of the adoption of the new accounting guidance for the recognition and measurement of equity securities. For further information on the Company’s valuation processes, see Note 6 in the Notes to Consolidated Financial Statements included in the Company’s 2017 Annual Report. The reconciliations for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) are as follows (dollars in thousands): For the three months ended June 30, 2018: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,299,264 $ 572,747 $ 120,614 $ 130,706 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (305 ) 3,468 (43 ) 76 Investment related gains (losses), net (3,141 ) — 312 1,282 Included in other comprehensive income 2,178 (3,517 ) (671 ) (1,544 ) Purchases (1) 155,498 — 24,412 — Sales (1) (11,089 ) — (4,961 ) — Settlements (1) (68,328 ) — (1,572 ) (19,544 ) Transfers into Level 3 — — 3,031 4,968 Transfers out of Level 3 (6,923 ) — (86,283 ) (45,258 ) Fair value, end of period $ 1,367,154 $ 572,698 $ 54,839 $ 70,686 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 $ (304 ) $ 3,468 $ (13 ) $ 68 Investment related gains (losses), net (3,141 ) — — — For the three months ended June 30, 2018 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 1,884 $ 21,053 $ 41,876 $ 5,004 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (107 ) (10 ) — Included in other comprehensive income (16 ) (173 ) (110 ) 40 Purchases (1) — 118 — — Settlements (1) (2 ) (156 ) (86 ) — Transfers out of Level 3 1 — (25,165 ) — Fair value, end of period $ 1,867 $ 20,735 $ 16,505 $ 5,044 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 $ — $ (108 ) $ (11 ) $ — For the three months ended June 30, 2018 (continued): Equity securities Funds withheld at interest- embedded derivatives Short-term Investments Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 36,152 $ 135,805 $ 3,217 $ 44,011 $ (964,794 ) $ (1,683 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — — — — — — Investment related gains (losses), net (4,922 ) 8,805 — — 15,324 — Claims & other policy benefits — — — — — — Interest credited — — — — 6,519 — Policy acquisition costs and other insurance expenses — — — — — — Included in other comprehensive income — — (21 ) (2,329 ) — — Other revenues — — — 2,289 — (799 ) Purchases (1) 12,248 — 335 — (4,205 ) — Sales (1) (541 ) — — — — — Settlements (1) — — (314 ) — 18,359 1,700 Transfers into Level 3 — — — — — — Transfers out of Level 3 — — — — — — Fair value, end of period $ 42,937 $ 144,610 $ 3,217 $ 43,971 $ (928,797 ) $ (782 ) 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 $ (5,000 ) $ 8,805 $ — $ — $ 13,474 $ — Other revenues — — — 2,289 — (799 ) Interest credited — — — — (11,839 ) — For the six months ended June 30, 2018: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,337,272 $ 593,942 $ 107,882 $ 123,474 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (666 ) 6,912 (135 ) 182 Investment related gains (losses), net (3,141 ) — 312 1,284 Included in other comprehensive income (30,674 ) (28,156 ) (1,781 ) (691 ) Purchases (1) 255,668 — 45,328 11,000 Sales (1) (17,269 ) — (4,961 ) — Settlements (1) (143,474 ) — (4,535 ) (22,283 ) Transfers into Level 3 7,166 — 3,031 4,968 Transfers out of Level 3 (37,728 ) — (90,302 ) (47,248 ) Fair value, end of period $ 1,367,154 $ 572,698 $ 54,839 $ 70,686 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 $ (665 ) $ 6,912 $ (105 ) $ 174 Investment related gains (losses), net (3,141 ) — — — For the six months ended June 30, 2018 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 3,234 $ 22,511 $ 41,203 $ 5,092 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (217 ) (2 ) — Included in other comprehensive income (63 ) (513 ) 590 (48 ) Purchases (1) — 214 — — Settlements (1) (3 ) (1,260 ) (121 ) — Transfers out of Level 3 (1,301 ) — (25,165 ) — Fair value, end of period $ 1,867 $ 20,735 $ 16,505 $ 5,044 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 $ — $ (218 ) $ (3 ) $ — For the six months ended June 30, 2018 (continued): Equity securities Funds withheld at interest- embedded derivatives Short-term Investments Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ — $ 122,194 $ 3,096 $ 40,659 $ (1,014,228 ) $ (1,683 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net (7,599 ) 22,416 — — 30,109 — Interest credited — — — — 31,870 — Included in other comprehensive income — — (46 ) (1,245 ) — — Other revenues — — — 4,557 — (799 ) Purchases (1) 12,248 — 481 — (12,713 ) — Sales (1) (569 ) — — — — — Settlements (1) (48 ) — (314 ) — 36,165 1,700 Transfers into Level 3 38,905 — — — — — Fair value, end of period $ 42,937 $ 144,610 $ 3,217 $ 43,971 $ (928,797 ) $ (782 ) 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 $ (7,705 ) $ 22,416 $ — $ — $ 26,375 $ — Other revenues — — — 4,557 — (799 ) Interest credited — — — — (4,295 ) — For the three months ended June 30, 2017: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,263,925 $ 483,560 $ 143,430 $ 208,436 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (396 ) 3,201 (29 ) 511 Investment related gains (losses), net 8,427 — 115 — Included in other comprehensive income (4,548 ) 46,509 1,962 1,136 Purchases (1) 104,087 — 29,318 34,366 Sales (1) (23,174 ) — (4,467 ) — Settlements (1) (74,531 ) — (4,655 ) (27,569 ) Transfers into Level 3 17,264 — 5,423 3,500 Transfers out of Level 3 — — (22,412 ) (18,791 ) Fair value, end of period $ 1,291,054 $ 533,270 $ 148,685 $ 201,589 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 $ (396 ) $ 3,201 $ (37 ) $ 239 Investment related gains (losses), net (1,495 ) — — — For the three months ended June 30, 2017 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 1,923 $ 23,474 $ 33,858 $ 12,344 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (115 ) (6 ) — Included in other comprehensive income 21 211 823 (12 ) Purchases (1) — 132 — — Settlements (1) (1 ) (135 ) (241 ) (338 ) Fair value, end of period $ 1,943 $ 23,567 $ 34,434 $ 11,994 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 $ — $ (115 ) $ (6 ) $ — For the three months ended June 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 $ 3,276 $ 46,173 $ 29,170 $ (972,930 ) $ (2,857 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 15,108 — 360 — Interest credited — — — (5,955 ) — Included in other comprehensive income (29 ) — 2,198 — — Other revenues — — 1,981 — (395 ) Purchases (1) 324 — — (19,533 ) — Settlements (1) (23 ) — — 23,427 1,700 Fair value, end of period $ 3,548 $ 61,281 $ 33,349 $ (974,631 ) $ (1,552 ) 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 $ — $ 15,108 $ — $ (1,794 ) $ — Other revenues — — 1,981 — (395 ) Interest credited — — — (29,382 ) — For the six months ended June 30, 2017: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS 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 (819 ) 6,271 (274 ) 1,529 Investment related gains (losses), net 7,196 — 480 — Included in other comprehensive income 400 51,034 2,612 6,903 Purchases (1) 150,001 — 45,817 45,215 Sales (1) (23,174 ) — (15,071 ) — Settlements (1) (146,001 ) — (11,439 ) (45,723 ) Transfers into Level 3 31,198 — 5,500 38,758 Transfers out of Level 3 — — (39,231 ) (64,373 ) Fair value, end of period $ 1,291,054 $ 533,270 $ 148,685 $ 201,589 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 $ (819 ) $ 6,271 $ (128 ) $ 400 Investment related gains (losses), net (2,788 ) — (346 ) — For the six months ended June 30, 2017 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government 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 (232 ) (94 ) — Investment related gains (losses), net (595 ) — — — Included in other comprehensive income (62 ) 263 (20 ) (203 ) Purchases (1) — 236 — — Sales (1) (3,720 ) — — — Settlements (1) (5,402 ) (1,188 ) (274 ) (672 ) Transfers out of Level 3 (10,132 ) — (6,844 ) — Fair value, end of period $ 1,943 $ 23,567 $ 34,434 $ 11,994 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 $ — $ (232 ) $ (94 ) $ — For the six months ended June 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 — 83,810 — 22,723 — Interest credited — — — (22,357 ) — Included in other comprehensive income 4 — 2,545 — — Other revenues — — 3,846 — (790 ) Purchases (1) 356 — — (25,927 ) — Settlements (1) (158 ) — — 41,238 1,700 Fair value, end of period $ 3,548 $ 61,281 $ 33,349 $ (974,631 ) $ (1,552 ) 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 $ — $ 83,810 $ — $ 18,505 $ — Other revenues — — 3,846 — (790 ) Interest credited — — — (63,596 ) — (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. Nonrecurring Fair Value Measurements During the six months ended June 30, 2018, the Company did not have any adjustments to its assets or liabilities measured at fair value on a nonrecurring basis that are still held at the reporting date. The following table presents information for assets measured at estimated fair value on a nonrecurring basis during the 2017 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) (dollars in thousands) At June 30, 2017 Three months ended June 30, 2017 Six months ended June 30, 2017 Limited partnership interests (1) $ 3,690 $ (6,308 ) $ (6,308 ) (1) 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. Fair Value of Financial Instruments The Company is required by general accounting principles for Fair Value Measurements and Disclosures to disclose the fair value of certain financial instruments including those that are not carried at fair value. 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 June 30, 2018 and December 31, 2017 (dollars in thousands). For additional information regarding the methods and significant assumptions used by the Company to estimate these fair values, see Note 6 in the Notes to Consolidated Financial Statements included in the Company’s 2017 Annual Report. 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. June 30, 2018: Carrying Value (1) Estimated Fair Value Fair Value Measurement Using: Level 1 Level 2 Level 3 NAV Assets: Mortgage loans on real estate $ 4,558,669 $ 4,461,317 $ — $ — $ 4,461,317 $ — Policy loans 1,339,252 1,339,252 — 1,339,252 — — Funds withheld at interest 5,836,373 6,057,217 — — 6,057,217 — Cash and cash equivalents 973,078 973,078 973,078 — — — Short-term investments 40,507 40,507 40,507 — — — Other invested assets 757,264 775,322 5,565 71,797 323,142 374,818 Accrued investment income 400,160 400,160 — 400,160 — — Liabilities: Interest-sensitive contract liabilities $ 13,072,239 $ 12,972,203 $ — $ — $ 12,972,203 $ — Long-term debt 2,788,111 2,868,837 — — 2,868,837 — Collateral finance and securitization notes 724,998 666,356 — — 666,356 — December 31, 2017: Carrying Value (1) Estimated Fair Value Fair Value Measurement Using: Level 1 Level 2 Level 3 NAV Assets: Mortgage loans on real estate $ 4,400,533 $ 4,477,654 $ — $ — $ 4,477,654 $ — Policy loans 1,357,624 1,357,624 — 1,357,624 — — Funds withheld at interest 5,955,092 6,275,623 — — 6,275,623 — Cash and cash equivalents 946,736 946,736 946,736 — — — Short-term investments 42,558 42,558 42,558 — — — Other invested assets 651,792 679,377 28,540 67,778 247,934 335,125 Accrued investment income 392,721 392,721 — 392,721 — — Liabilities: Interest-sensitive contract liabilities $ 12,683,872 $ 12,917,243 $ — $ — $ 12,917,243 $ — Long-term debt 2,788,365 2,959,912 — — 2,959,912 — Collateral finance and securitization notes 783,938 722,145 — — 722,145 — (1) Carrying values presented herein may differ from those in the Company’s condensed consolidated balance sheets because certain items within the respective financial statement captions may be measured at fair value on a recurring basis.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2018
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 2017 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 June 30, Six months ended June 30, Revenues: 2018 2017 2018 2017 U.S. and Latin America: Traditional $ 1,564,147 $ 1,522,698 $ 3,053,841 $ 3,011,201 Financial Solutions 229,948 271,976 443,300 570,822 Total 1,794,095 1,794,674 3,497,141 3,582,023 Canada: Traditional 312,199 269,273 614,518 533,548 Financial Solutions 12,089 12,003 24,866 23,810 Total 324,288 281,276 639,384 557,358 Europe, Middle East and Africa: Traditional 372,538 345,920 766,320 664,006 Financial Solutions 100,675 73,405 188,818 153,394 Total 473,213 419,325 955,138 817,400 Asia Pacific: Traditional 570,520 561,529 1,185,059 1,066,759 Financial Solutions 17,992 17,984 37,838 38,436 Total 588,512 579,513 1,222,897 1,105,195 Corporate and Other 15,800 54,488 55,055 76,040 Total $ 3,195,908 $ 3,129,276 $ 6,369,615 $ 6,138,016 Three months ended June 30, Six months ended June 30, Income (loss) before income taxes: 2018 2017 2018 2017 U.S. and Latin America: Traditional $ 71,978 $ 90,594 $ 74,870 $ 120,554 Financial Solutions 82,388 106,985 149,809 210,571 Total 154,366 197,579 224,679 331,125 Canada: Traditional 21,805 32,836 45,512 52,164 Financial Solutions 3,544 4,425 6,735 8,017 Total 25,349 37,261 52,247 60,181 Europe, Middle East and Africa: Traditional 6,468 11,354 21,889 25,330 Financial Solutions 65,369 28,905 104,533 60,823 Total 71,837 40,259 126,422 86,153 Asia Pacific: Traditional 58,862 53,322 81,749 95,010 Financial Solutions 4,138 5,377 8,159 11,249 Total 63,000 58,699 89,908 106,259 Corporate and Other (67,264 ) 5,517 (108,043 ) (36,559 ) Total $ 247,288 $ 339,315 $ 385,213 $ 547,159 Assets: June 30, 2018 December 31, 2017 U.S. and Latin America: Traditional $ 19,038,145 $ 18,603,423 Financial Solutions 16,043,393 15,959,206 Total 35,081,538 34,562,629 Canada: Traditional 4,203,344 4,161,452 Financial Solutions 141,581 126,372 Total 4,344,925 4,287,824 Europe, Middle East and Africa: Traditional 3,335,264 3,099,495 Financial Solutions 4,829,194 5,274,993 Total 8,164,458 8,374,488 Asia Pacific: Traditional 5,159,546 4,915,442 Financial Solutions 1,156,371 1,198,585 Total 6,315,917 6,114,027 Corporate and Other 5,859,659 7,175,850 Total $ 59,766,497 $ 60,514,818

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 are presented in the following table (dollars in thousands): June 30, 2018 December 31, 2017 Limited partnership interests and joint ventures $ 490,601 $ 485,197 Commercial mortgage loans 113,992 40,815 Bank loans and private placements 98,652 60,472 Equity release mortgages 157,069 153,937 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. Bank loans and private placements are included in fixed maturity securities available-for-sale. 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 June 30, 2018 , 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 June 30, 2018 (dollars in millions): Commitment Period: Maximum Potential Obligation 2023 $ 500.0 2033 450.0 2034 2,000.0 2035 1,314.2 2036 1,932.0 2037 6,750.0 2038 800.0 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 June 30, 2018 and December 31, 2017 are reflected in the following table (dollars in thousands): June 30, 2018 December 31, 2017 Treaty guarantees $ 913,902 $ 1,047,449 Treaty guarantees, net of assets in trust 802,073 926,393 Securities borrowing and repurchase arrangements 289,210 294,325 Financing arrangements 74,864 86,183 Lease obligations 1,137 1,662

Income Tax

Income Tax	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Tax The Company's effective tax rates differed from the applicable U.S. federal income tax statutory rates of 21% and 35% as a result of the following for the three and six months ended June 30, 2018 and 2017 , respectively (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Tax provision at U.S. statutory rate $ 51,931 $ 118,760 $ 80,895 $ 191,506 Increase (decrease) in income taxes resulting from: U.S. Tax Reform provisional adjustments (4,314 ) — (3,539 ) — Foreign tax rate differing from U.S. tax rate (330 ) (4,261 ) 1,103 (10,413 ) Differences in tax bases in foreign jurisdictions (1,132 ) (13,375 ) (6,892 ) (16,759 ) Deferred tax valuation allowance 3,079 13,031 10,501 14,213 Amounts related to tax audit contingencies (2,036 ) (1,783 ) (1,201 ) (1,172 ) Corporate rate changes 145 44 417 (1,193 ) Subpart F (348 ) 1,140 310 1,326 Foreign tax credits 113 (1,938 ) (459 ) (2,064 ) Global intangible low-taxed income, net of credit (119 ) — 4,291 — Equity compensation excess benefit (3,135 ) (2,609 ) (4,250 ) (4,464 ) Return to provision adjustments (503 ) (633 ) (139 ) (403 ) Other, net (437 ) (1,251 ) (428 ) (1,120 ) Total provision for income taxes $ 42,914 $ 107,125 $ 80,609 $ 169,457 Effective tax rate 17.4 % 31.6 % 20.9 % 31.0 % On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“U.S. Tax Reform”) was signed into law. U.S. Tax Reform makes broad and complex changes to the U.S. tax code, including but not limited to, (1) reducing the U.S. federal corporate tax rate from 35% to 21%; (2) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries; (4) eliminating the corporate alternative minimum tax (“AMT”) and changing how existing AMT credits can be realized; (5) creating the base erosion anti-abuse tax (“BEAT”), a new minimum tax; (6) establishing a new provision designed to tax global intangible low-taxed income (“GILTI”), which allows for the possibility of using foreign tax credits and a deduction of up to 50 percent to offset the income tax liability (subject to some limitations); and (7) changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after December 31, 2017. Companies subject to GILTI have the option to account for the GILTI tax as a period cost if and when incurred, or to recognize deferred taxes for temporary differences including outside basis differences expected to reverse as GILTI. The Company has not yet made a policy election to account for GILTI, but included an estimate of the current GILTI impact in the tax provision. As of June 30, 2018, the Company has not yet completed its accounting for the tax effects of the enactment of U.S. Tax Reform. The Company continues to gather additional information to account for the effects of U.S. Tax Reform such as information to more precisely compute the pretax deferred tax items upon which the change in rate was applied and refine the necessary valuation allowance. The Company also continues to monitor the issuance of new guidance in the form of Treasury Regulations which could impact the provisional balances recorded as of December 31, 2017. The Company continues to evaluate the effects of the BEAT and is currently restructuring existing business flows to reduce the risk that the Company will be subject to the BEAT for 2018. The Company has estimated that the annual deductible payments to foreign affiliates as a percentage of annual estimated total deductions to be below the threshold for application of the BEAT; therefore, the Company has not established an additional BEAT liability as of June 30, 2018. The effective tax rates for the second quarter and first six months of 2018 were lower than the U.S. Statutory rate of 21.0% primarily as a result of U.S. Tax Reform related adjustments, the effective settlement of an uncertain tax position, benefits from differences in bases in foreign jurisdictions and excess tax benefits related to equity compensation. These benefits were partially offset by valuation allowances established on losses in foreign jurisdictions. The effective tax rates for the second quarter and first six months of 2017 were lower than the U.S. Statutory rate of 35% primarily as a result of tax benefits from income in non-U.S. jurisdictions, mostly related to RGA Life Reinsurance Company of Canada and the United Kingdom Branch of RGA International Reinsurance Company dac, with statutory rates of 26.6% and 19.3%, respectively. Further, tax benefits derived from differences in tax bases in foreign jurisdictions and benefits related to the filing of an amended tax return also lowered the effective tax rate. These benefits were partially offset with a valuation allowance established related to the amended return filing.

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
	Jun. 30, 2018
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 six months ended June 30, 2018 and 2017 were as follows (dollars in thousands): Pension Benefits Other Benefits Three months ended June 30, Three months ended June 30, 2018 2017 2018 2017 Service cost $ 3,570 $ 2,819 $ 636 $ 721 Interest cost 1,357 1,431 529 565 Expected return on plan assets (2,213 ) (1,823 ) — — Amortization of prior service cost (credit) 82 95 (329 ) (155 ) Amortization of prior actuarial losses 769 1,082 498 457 Settlements — 256 — — Net periodic benefit cost $ 3,565 $ 3,860 $ 1,334 $ 1,588 Pension Benefits Other Benefits Six months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Service cost $ 6,224 $ 5,399 $ 1,272 $ 1,442 Interest cost 2,687 2,629 1,059 1,130 Expected return on plan assets (3,767 ) (3,108 ) — — Amortization of prior service cost (credit) 165 169 (658 ) (311 ) Amortization of prior actuarial losses 1,863 2,163 996 914 Settlements — 513 — — Net periodic benefit cost $ 7,172 $ 7,765 $ 2,669 $ 3,175 The Company made $5.0 million in pension contributions during the first six months of 2018 and expects to make total pension contributions between $8.0 million and $10.0 million in 2018.

Reinsurance

Reinsurance	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 , 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 June 30, 2018 and December 31, 2017 , all rated retrocession pool participants followed by the A.M. Best Company were rated “A- (excellent)” or better, except for one pool member that was rated “ B++ ”. 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 June 30, 2018 or December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 Reinsurer A.M. Best Rating Amount % of Total Amount % of Total Reinsurer A A+ $ 312,405 39.6 $ 301,478 38.6 % Reinsurer B A+ 198,782 25.2 203,898 26.1 Reinsurer C A 67,699 8.6 67,723 8.7 Reinsurer D A+ 41,807 5.3 40,528 5.2 Reinsurer E A++ 38,935 4.9 40,592 5.2 Other reinsurers 129,801 16.4 127,808 16.2 Total $ 789,429 100.0 % $ 782,027 100.0 % Included in the total reinsurance ceded receivables balance were $271.2 million and $243.8 million of claims recoverable, of which $3.1 million and $1.9 million were in excess of 90 days past due, as of June 30, 2018 and December 31, 2017 , respectively.

New Accounting Standards

New Accounting Standards	6 Months Ended
	Jun. 30, 2018
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. Description Date of Adoption Effect on the financial statements or other significant matters Standards adopted: Reporting Comprehensive Income This updated guidance requires reclassification from accumulated other comprehensive income to retained earnings for the stranded tax effects resulting from the newly enacted U.S. federal corporate income tax rate. The amount of the reclassification would be the difference between the historical U.S. federal corporate income tax rate and the newly enacted 21 percent tax rate. December 31, 2017 The Company adopted the new guidance by reclassifying certain income tax effects of items within accumulated other comprehensive income to retained earnings as a result of the Tax Cuts and Jobs Act of 2017. The impact of adopting this standard was an increase in accumulated other comprehensive income and a reduction in retained earnings of approximately $156.4 million. Stock Compensation This 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. 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 $10.5 million in the provision for income taxes for the year ended December 31, 2017. 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 consolidated financial statements. Financial Instruments - Recognition and Measurement This guidance requires equity investments that are not accounted for under the equity method of accounting to be measured at fair value with changes recognized in net income and also updates certain presentation and disclosure requirements. January 1, 2018 This guidance required a cumulative-effect adjustment for certain items upon adoption. The adoption of the new guidance was not material to the Company's consolidated financial statements. Standards not yet adopted: Leases This 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. Early adoption is permitted. January 1, 2019 This new standard will be adopted by applying a modified retrospective transition approach, which includes a number of practical expedients. The Company is currently evaluating the impact of this amendment on its consolidated financial statements; however, it does not expect the adoption of the new standard to have a material impact on its results of operations or balance sheet as a result of the recognition of right-to-use assets and lease liabilities related to operating leases. Contractual obligations related to operating leases totaled approximately $38.2 million as of December 31, 2017. Derivatives and Hedging This 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. Early adoption is permitted. January 1, 2019 This new guidance will be adopted by applying a modified retrospective approach to existing hedging relationships as of the date of adoption. The Company is currently evaluating the impact of this updated guidance on its consolidated financial statements. Financial Instruments - Credit Losses This guidance 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. Early adoption is permitted. January 1, 2020 This 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 consolidated financial statements.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table 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 June 30, Six months ended June 30, 2018 2017 2018 2017 Earnings: Net income (numerator for basic and diluted calculations) $ 204,374 $ 232,190 $ 304,604 $ 377,702 Shares: Weighted average outstanding shares (denominator for basic calculation) 64,071 64,449 64,278 64,401 Equivalent shares from outstanding stock options 1,179 1,159 1,277 1,204 Denominator for diluted calculation 65,250 65,608 65,555 65,605 Earnings per share: Basic $ 3.19 $ 3.60 $ 4.74 $ 5.86 Diluted $ 3.13 $ 3.54 $ 4.65 $ 5.76
Schedule Of Earnings Per Share Basic And Diluted By Common Class [Text Block]	The following table presents approximate amounts of stock options and performance contingent shares excluded from the calculation of common equivalent shares (in millions): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Excluded from common equivalent shares: Stock options 0.2 0.2 0.3 0.3 Performance contingent shares 0.2 0.3 0.2 0.3

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2018
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, 2017 79,137,758 14,685,663 64,452,095 Common stock acquired — 991,477 (991,477 ) Stock-based compensation (1) — (211,868 ) 211,868 Balance, June 30, 2018 79,137,758 15,465,272 63,672,486 Issued Held In Treasury Outstanding Balance, December 31, 2016 79,137,758 14,835,256 64,302,502 Stock-based compensation (1) — (189,355 ) 189,355 Balance, June 30, 2017 79,137,758 14,645,901 64,491,857 (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 six months ended June 30, 2018 and 2017 are as follows (dollars in thousands): Accumulated Currency Translation Adjustments Unrealized Appreciation (Depreciation) of Investments (1) Pension and Postretirement Benefits Total Balance, December 31, 2017 $ (86,350 ) $ 2,200,661 $ (50,680 ) $ 2,063,631 Other comprehensive income (loss) before reclassifications (44,227 ) (1,327,195 ) (2,986 ) (1,374,408 ) Amounts reclassified to (from) AOCI — 53,646 2,366 56,012 Deferred income tax benefit (expense) (11,610 ) 271,226 120 259,736 Balance, June 30, 2018 $ (142,187 ) $ 1,198,338 $ (51,180 ) $ 1,004,971 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 (13,936 ) 774,688 (196 ) 760,556 Amounts reclassified to (from) AOCI — (39,360 ) 2,935 (36,425 ) Deferred income tax benefit (expense) 35,288 (225,884 ) (966 ) (191,562 ) Balance, June 30, 2017 $ (151,189 ) $ 1,864,477 $ (41,390 ) $ 1,671,898 (1) Includes cash flow hedges of $22,656 and $2,619 as of June 30, 2018 and December 31, 2017 , respectively, and $1,131 and $(2,496) as of June 30, 2017 and December 31, 2016 , 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 six months ended June 30, 2018 and 2017 (dollars in thousands): Amount Reclassified from AOCI Three months ended June 30, Six months ended June 30, Details about AOCI Components 2018 2017 2018 2017 Affected Line Item in Statements of Income Net unrealized investment gains (losses): Net unrealized gains (losses) on available-for-sale securities $ (24,642 ) $ 40,374 $ (39,098 ) $ 28,517 Investment related gains (losses), net Cash flow hedges - Interest rate 29 — (342 ) — (1) Cash flow hedges - Currency/Interest rate 76 132 221 329 (1) Cash flow hedges - Forward bond purchase commitments — 51 — 101 (1) Deferred policy acquisition costs attributed to unrealized gains and losses (7,835 ) 4,565 (14,427 ) 10,413 (2) Total (32,372 ) 45,122 (53,646 ) 39,360 Provision for income taxes 6,945 (15,218 ) 11,623 (12,024 ) Net unrealized gains (losses), net of tax $ (25,427 ) $ 29,904 $ (42,023 ) $ 27,336 Amortization of defined benefit plan items: Prior service cost (credit) $ 247 $ 60 $ 493 $ 142 (3) Actuarial gains/(losses) (1,267 ) (1,539 ) (2,859 ) (3,077 ) (3) Total (1,020 ) (1,479 ) (2,366 ) (2,935 ) Provision for income taxes 214 517 497 1,027 Amortization of defined benefit plans, net of tax $ (806 ) $ (962 ) $ (1,869 ) $ (1,908 ) Total reclassifications for the period $ (26,233 ) $ 28,942 $ (43,892 ) $ 25,428 (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 2017 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)	6 Months Ended
	Jun. 30, 2018
Investments [Abstract]
Available For Sale Securities	The following table provides information relating to investments in fixed maturity securities by sector as of June 30, 2018 (dollars in thousands): June 30, 2018: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate $ 22,249,964 $ 663,087 $ 409,544 $ 22,503,507 61.2 % $ — Canadian government 2,789,699 1,277,020 3,876 4,062,843 11.0 — RMBS 1,837,316 18,500 34,602 1,821,214 5.0 — ABS 1,711,099 11,596 13,871 1,708,824 4.6 275 CMBS 1,249,616 8,591 15,698 1,242,509 3.4 — U.S. government 1,583,622 8,193 66,665 1,525,150 4.1 — State and political subdivisions 703,047 43,318 9,321 737,044 2.0 — Other foreign government 3,109,607 112,887 38,631 3,183,863 8.7 — Total fixed maturity securities $ 35,233,970 $ 2,143,192 $ 592,208 $ 36,784,954 100.0 % $ 275 The following table provides information relating to investments in fixed maturity and equity securities by sector as of December 31, 2017 (dollars in thousands): December 31, 2017: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate $ 21,966,803 $ 1,299,594 $ 55,429 $ 23,210,968 60.9 % $ — Canadian government 2,843,273 1,378,510 1,707 4,220,076 11.1 — RMBS 1,695,126 36,632 11,878 1,719,880 4.5 — ABS 1,634,758 18,798 5,194 1,648,362 4.3 275 CMBS 1,285,594 22,627 4,834 1,303,387 3.4 — U.S. government 1,953,436 12,089 21,933 1,943,592 5.1 — State and political subdivisions 647,727 59,997 4,296 703,428 1.8 — Other foreign government 3,254,695 154,507 8,075 3,401,127 8.9 — Total fixed maturity securities $ 35,281,412 $ 2,982,754 $ 113,346 $ 38,150,820 100.0 % $ 275 Non-redeemable preferred stock $ 41,553 $ 479 $ 2,226 $ 39,806 39.7 % Other equity securities 61,288 479 1,421 60,346 60.3 Total equity securities $ 102,841 $ 958 $ 3,647 $ 100,152 100.0 %
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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities pledged as collateral $ 63,640 $ 66,118 $ 72,542 $ 75,622 Fixed maturity securities received as collateral n/a 626,081 n/a 590,417 Assets in trust held to satisfy collateral requirements 16,061,218 16,571,173 15,584,296 16,715,281
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 June 30, 2018 and December 31, 2017 (dollars in thousands). June 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities guaranteed or issued by: Canadian province of Quebec $ 1,101,825 $ 1,850,642 $ 1,119,337 $ 1,917,996 Canadian province of Ontario 929,913 1,239,102 939,837 1,282,944
Investments Classified By Contractual Maturity Date	The amortized cost and estimated fair value of fixed maturity securities classified as available-for-sale at June 30, 2018 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 $ 978,683 $ 986,160 Due after one year through five years 7,550,595 7,649,023 Due after five years through ten years 9,208,763 9,323,786 Due after ten years 12,697,898 14,053,438 Asset and mortgage-backed securities 4,798,031 4,772,547 Total $ 35,233,970 $ 36,784,954
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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018: Estimated Amortized Cost Fair Value % of Total Finance $ 8,097,947 $ 8,129,125 36.2 % Industrial 11,705,150 11,847,762 52.6 Utility 2,446,867 2,526,620 11.2 Total $ 22,249,964 $ 22,503,507 100.0 % December 31, 2017: Estimated Amortized Cost Fair Value % of Total Finance $ 7,977,885 $ 8,362,774 36.1 % Industrial 11,535,166 12,199,333 52.5 Utility 2,453,752 2,648,861 11.4 Total $ 21,966,803 $ 23,210,968 100.0 %
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 June 30, Six months ended June 30, 2018 2017 2018 2017 Balance, beginning of period $ 3,677 $ 3,677 $ 3,677 $ 6,013 Credit loss OTTI previously recognized on securities impaired to fair value during the period — — — (2,336 ) Balance, end of period $ 3,677 $ 3,677 $ 3,677 $ 3,677
Investments In Debt And Equity Securities Gross Unrealized Losses Disclosures	The following table presents the total gross unrealized losses for the 2,580 fixed maturity securities as of June 30, 2018 , where the estimated fair value had declined and remained below amortized cost by the indicated amount (dollars in thousands): June 30, 2018 Gross Unrealized Losses % of Total Less than 20% $ 571,151 96.4 % 20% or more for less than six months 21,045 3.6 20% or more for six months or greater 12 — Total $ 592,208 100.0 % The following table presents the total gross unrealized losses for the 1,116 fixed maturity and equity securities at December 31, 2017 where the estimated fair value had declined and remained below amortized cost by the indicated amount (dollars in thousands): December 31, 2017 Gross % of Total Less than 20% $ 113,466 97.0 % 20% or more for less than six months 689 0.6 20% or more for six months or greater 2,838 2.4 Total $ 116,993 100.0 %
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block]	The following table presents the estimated fair values and gross unrealized losses, including other-than-temporary impairment losses reported in AOCI, for 2,580 fixed maturity securities that have estimated fair values below amortized cost as of June 30, 2018 (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 June 30, 2018: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate $ 9,135,620 $ 299,909 $ 818,555 $ 51,938 $ 9,954,175 $ 351,847 Canadian government 46,392 668 110,326 3,058 156,718 3,726 RMBS 1,101,941 25,546 241,914 9,032 1,343,855 34,578 ABS 807,714 10,637 139,676 3,187 947,390 13,824 CMBS 612,214 11,097 104,426 4,601 716,640 15,698 U.S. government 584,758 20,707 747,679 45,958 1,332,437 66,665 State and political subdivisions 168,817 5,064 66,122 4,257 234,939 9,321 Other foreign government 919,229 25,758 199,578 5,407 1,118,807 31,165 Total investment grade securities 13,376,685 399,386 2,428,276 127,438 15,804,961 526,824 Below investment grade securities: Corporate 735,338 47,846 56,042 9,851 791,380 57,697 Canadian government 1,864 150 — — 1,864 150 RMBS — — 1,194 24 1,194 24 ABS — — 1,148 47 1,148 47 Other foreign government 146,374 7,111 7,643 355 154,017 7,466 Total below investment grade securities 883,576 55,107 66,027 10,277 949,603 65,384 Total fixed maturity securities $ 14,260,261 $ 454,493 $ 2,494,303 $ 137,715 $ 16,754,564 $ 592,208 The following table presents the estimated fair values and gross unrealized losses, including other-than-temporary impairment losses reported in AOCI, for 1,116 fixed maturity and equity securities that have estimated fair values below amortized cost as of December 31, 2017 (dollars in thousands): Less than 12 months 12 months or greater Total Gross Gross Gross December 31, 2017: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate $ 1,886,212 $ 17,099 $ 1,009,750 $ 28,080 $ 2,895,962 $ 45,179 Canadian government 18,688 91 111,560 1,596 130,248 1,687 RMBS 566,699 5,852 224,439 6,004 791,138 11,856 ABS 434,274 2,707 168,524 2,434 602,798 5,141 CMBS 220,401 1,914 103,269 2,920 323,670 4,834 U.S. government 800,298 6,177 767,197 15,756 1,567,495 21,933 State and political subdivisions 43,510 242 68,666 4,054 112,176 4,296 Other foreign government 369,717 2,707 191,265 4,704 560,982 7,411 Total investment grade securities 4,339,799 36,789 2,644,670 65,548 6,984,469 102,337 Below investment grade securities: Corporate 194,879 3,317 75,731 6,933 270,610 10,250 Canadian government 1,995 20 — — 1,995 20 RMBS — — 1,369 22 1,369 22 ABS — — 1,489 53 1,489 53 Other foreign government 28,600 113 15,134 551 43,734 664 Total below investment grade securities 225,474 3,450 93,723 7,559 319,197 11,009 Total fixed maturity securities $ 4,565,273 $ 40,239 $ 2,738,393 $ 73,107 $ 7,303,666 $ 113,346 Non-redeemable preferred stock $ 82 $ 1 $ 26,471 $ 2,225 $ 26,553 $ 2,226 Other equity securities 5,820 1,023 47,251 398 53,071 1,421 Total equity securities $ 5,902 $ 1,024 $ 73,722 $ 2,623 $ 79,624 $ 3,647
Investment Income	Major categories of investment income, net of related expenses, consist of the following (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Fixed maturity securities available-for-sale $ 373,624 $ 355,735 $ 742,827 $ 680,235 Equity securities 709 995 2,391 2,354 Mortgage loans on real estate 50,460 44,442 100,659 88,789 Policy loans 14,775 15,194 29,555 30,466 Funds withheld at interest 86,417 97,367 161,862 224,945 Short-term investments and cash and cash equivalents 2,964 1,779 6,209 3,289 Other invested assets 20,785 22,071 44,613 40,539 Investment income 549,734 537,583 1,088,116 1,070,617 Investment expense (21,673 ) (19,045 ) (43,726 ) (37,715 ) Investment income, net of related expenses $ 528,061 $ 518,538 $ 1,044,390 $ 1,032,902
Gain Loss On Investments	Investment related gains (losses), net consist of the following (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Fixed maturity securities available for sale: Other-than-temporary impairment losses $ (3,350 ) $ (3,401 ) $ (3,350 ) $ (20,590 ) Gain on investment activity 21,140 54,197 32,106 72,090 Loss on investment activity (35,934 ) (10,288 ) (56,314 ) (18,975 ) Equity securities: Gain on investment activity 469 23 497 23 Loss on investment activity — (183 ) (950 ) (4,059 ) Change in unrealized gains (losses) recognized in earnings (6,966 ) — (11,103 ) — Other impairment losses and change in mortgage loan provision (1,357 ) (6,675 ) (1,669 ) (6,774 ) Derivatives and other, net 15,426 22,622 29,741 95,103 Total investment related gains (losses), net $ (10,572 ) $ 56,295 $ (11,042 ) $ 116,818
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 June 30, 2018 and December 31, 2017 (dollars in thousands). June 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Borrowed securities $ 350,350 $ 365,730 $ 358,875 $ 377,820 Securities lending: Securities loaned 101,995 102,208 117,246 121,551 Securities received n/a 112,000 n/a 128,000 Repurchase program/reverse repurchase program: Securities pledged 385,391 394,698 413,819 428,344 Securities received n/a 397,712 n/a 417,550
Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets [Table Text Block]	The following tables present information on the Company’s securities lending and repurchase transactions as of June 30, 2018 and December 31, 2017 (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. June 30, 2018 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 $ — $ — $ — $ 102,208 $ 102,208 Total — — — 102,208 102,208 Repurchase transactions: Corporate — — — 151,519 151,519 U.S. government — — — 219,154 219,154 Foreign government — — — 22,894 22,894 Other 1,131 — — — 1,131 Total 1,131 — — 393,567 394,698 Total transactions $ 1,131 $ — $ — $ 495,775 $ 496,906 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 539,332 Amounts related to agreements not included in offsetting disclosure $ 42,426 December 31, 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 $ — $ — $ — $ 121,551 $ 121,551 Total $ — $ — $ — $ 121,551 $ 121,551 Repurchase transactions: Corporate $ — $ — $ 312 $ 184,334 $ 184,646 U.S. government — — — 220,765 220,765 Foreign government — — — 21,802 21,802 Other 1,131 — — — 1,131 Total 1,131 — 312 426,901 428,344 Total borrowings $ 1,131 $ — $ 312 $ 548,452 $ 549,895 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 576,786 Amounts related to agreements not included in offsetting disclosure $ 26,891
Disclosure Of Real Estate Holdings By Property Type [Table Text Block]	The distribution of mortgage loans by property type is as follows as of June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 Property type: Carrying Value % of Total Carrying Value % of Total Office building $ 1,546,148 33.9 % $ 1,487,392 33.6 % Retail 1,296,157 28.3 1,270,676 28.8 Industrial 962,049 21.0 938,612 21.3 Apartment 530,599 11.6 510,052 11.6 Other commercial 237,610 5.2 206,439 4.7 Recorded investment 4,572,563 100.0 % 4,413,171 100.0 % Unamortized balance of loan origination fees and expenses (4,188 ) (3,254 ) Valuation allowances (9,706 ) (9,384 ) Total mortgage loans on real estate $ 4,558,669 $ 4,400,533
Mortgage Loans Classified By Contractual Maturity Date [Table Text Block]	The maturities of the mortgage loans as of June 30, 2018 and December 31, 2017 are as follows (dollars in thousands): June 30, 2018 December 31, 2017 Recorded Investment % of Total Recorded Investment % of Total Due within five years $ 1,153,623 25.2 % $ 1,091,066 24.8 % Due after five years through ten years 2,623,105 57.4 2,516,872 57.0 Due after ten years 795,835 17.4 805,233 18.2 Total $ 4,572,563 100.0 % $ 4,413,171 100.0 %
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 June 30, 2018 and December 31, 2017 (dollars in thousands): Recorded Investment Debt Service Ratios Construction loans >1.20x 1.00x - 1.20x <1.00x Total % of Total June 30, 2018: Loan-to-Value Ratio 0% - 59.99% $ 2,125,328 $ 102,254 $ 19,439 $ 17,602 $ 2,264,623 49.5 % 60% - 69.99% 1,552,568 117,751 49,221 — 1,719,540 37.6 70% - 79.99% 315,274 25,121 101,213 — 441,608 9.7 Greater than 80% 101,870 12,933 31,989 — 146,792 3.2 Total $ 4,095,040 $ 258,059 $ 201,862 $ 17,602 $ 4,572,563 100.0 % Recorded Investment Debt Service Ratios Construction loans >1.20x 1.00x - 1.20x <1.00x Total % of Total December 31, 2017: Loan-to-Value Ratio 0% - 59.99% $ 2,148,428 $ 53,979 $ 3,801 $ — $ 2,206,208 50.0 % 60% - 69.99% 1,517,029 47,128 43,921 — 1,608,078 36.4 70% - 79.99% 396,446 19,461 15,367 — 431,274 9.8 Greater than 80% 120,850 30,713 6,362 9,686 167,611 3.8 Total $ 4,182,753 $ 151,281 $ 69,451 $ 9,686 $ 4,413,171 100.0 %
Past Due Financing Receivables [Table Text Block]	The age analysis of the Company’s past due recorded investments in mortgage loans as of June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 31-60 days past due $ 12,027 $ 17,100 61-90 days past due — 2,056 Total past due 12,027 19,156 Current 4,560,536 4,394,015 Total $ 4,572,563 $ 4,413,171
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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 Mortgage loans: Individually measured for impairment $ 30,653 $ 5,858 Collectively measured for impairment 4,541,910 4,407,313 Recorded investment $ 4,572,563 $ 4,413,171 Valuation allowances: Individually measured for impairment $ — $ — Collectively measured for impairment 9,706 9,384 Total valuation allowances $ 9,706 $ 9,384
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 six months ended June 30, 2018 and 2017 is as follows (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Balance, beginning of period $ 8,864 $ 7,786 $ 9,384 $ 7,685 Provision (release) 845 366 329 467 Translation adjustment (3 ) 4 (7 ) 4 Balance, end of period $ 9,706 $ 8,156 $ 9,706 $ 8,156
Impaired Financing Receivables Table	Information regarding the portion of the Company’s mortgage loans that were impaired as of June 30, 2018 and December 31, 2017 is as follows (dollars in thousands): Unpaid Principal Balance Recorded Investment Related Allowance Carrying Value June 30, 2018: Impaired mortgage loans with no valuation allowance recorded $ 30,690 $ 30,653 $ — $ 30,653 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 30,690 $ 30,653 $ — $ 30,653 December 31, 2017: Impaired mortgage loans with no valuation allowance recorded $ 6,427 $ 5,858 $ — $ 5,858 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 6,427 $ 5,858 $ — $ 5,858 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 June 30, 2018 2017 Average (1) Interest Income Average Recorded Investment (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 27,038 $ 247 $ 2,088 $ 33 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 27,038 $ 247 $ 2,088 $ 33 Six months ended June 30, 2018 2017 Average (1) Interest Income Average (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 19,978 $ 304 $ 2,131 $ 67 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 19,978 $ 304 $ 2,131 $ 67 (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 June 30, 2018 and December 31, 2017 are as follows (dollars in thousands): June 30, 2018 December 31, 2017 Limited partnership interests and real estate joint ventures $ 857,599 $ 781,124 Equity release mortgages 311,723 219,940 Derivatives 137,315 137,613 FVO contractholder-directed unit-linked investments 212,202 218,541 Other 86,723 148,114 Total other invested assets $ 1,605,562 $ 1,505,332

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 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 $ 1,084,555 $ 43,439 $ 2,514 $ 996,204 $ 59,809 $ 2,372 Financial futures 348,874 — — 412,438 — — Foreign currency forwards 4,512 — 8 6,030 — 28 Consumer price index swaps 328,190 1,126 199 221,932 — 2,160 Credit default swaps 928,300 6,725 122 961,200 8,319 1,651 Equity options 639,801 25,950 — 632,251 23,271 — Longevity swaps 934,720 43,971 — 960,400 40,659 — Mortality swaps 25,000 — 782 — — 1,683 Synthetic guaranteed investment contracts 10,634,677 — — 10,052,576 — — Embedded derivatives in: Modified coinsurance or funds withheld arrangements — 144,610 — — 122,194 — Indexed annuity products — — 806,436 — — 861,758 Variable annuity products — — 122,361 — — 152,470 Total non-hedging derivatives 14,928,629 265,821 932,422 14,243,031 254,252 1,022,122 Derivatives designated as hedging instruments: Interest rate swaps 435,000 204 19,699 435,000 — 20,389 Foreign currency swaps 580,036 58,294 2,598 672,921 65,207 8,496 Foreign currency forwards 718,177 18,428 — 553,175 1,265 7,720 Total hedging derivatives 1,733,213 76,926 22,297 1,661,096 66,472 36,605 Total derivatives $ 16,661,842 $ 342,747 $ 954,719 $ 15,904,127 $ 320,724 $ 1,058,727
Offsetting Assets [Table Text Block]	The following table provides information relating to the Company’s derivative instruments as of June 30, 2018 and December 31, 2017 (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 June 30, 2018: Derivative assets $ 198,137 $ (16,851 ) $ 181,286 $ — $ (194,067 ) $ (12,781 ) Derivative liabilities 25,922 (16,851 ) 9,071 (57,302 ) (9,030 ) (57,261 ) December 31, 2017: Derivative assets $ 198,530 $ (20,258 ) $ 178,272 $ (862 ) $ (185,900 ) $ (8,490 ) Derivative liabilities 44,499 (20,258 ) 24,241 (58,156 ) (22,221 ) (56,136 ) (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 June 30, 2018 and December 31, 2017 (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 June 30, 2018: Derivative assets $ 198,137 $ (16,851 ) $ 181,286 $ — $ (194,067 ) $ (12,781 ) Derivative liabilities 25,922 (16,851 ) 9,071 (57,302 ) (9,030 ) (57,261 ) December 31, 2017: Derivative assets $ 198,530 $ (20,258 ) $ 178,272 $ (862 ) $ (185,900 ) $ (8,490 ) Derivative liabilities 44,499 (20,258 ) 24,241 (58,156 ) (22,221 ) (56,136 ) (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 June 30, 2018 and 2017, were (dollars in thousands): Type of Fair Value Hedge Hedged Item Gains (Losses) Recognized for Derivatives (1) Gains (Losses) Recognized for Hedged Items (1) For the three months ended June 30, 2018: Foreign currency swaps Foreign-denominated fixed maturity securities $ (1,134 ) $ 4,942 For the three months ended June 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 905 $ (905 ) For the six months ended June 30, 2018: Foreign currency swaps Foreign-denominated fixed maturity securities $ (3,025 ) $ 6,833 For the six months ended June 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 7,441 $ (7,441 )
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 six months ended June 30, 2018 and 2017 (dollars in thousands): Three months ended June 30, 2018 2017 Balance beginning of period $ 20,662 $ 7,690 Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges 2,099 (6,417 ) Amounts reclassified to investment related (gains) losses, net — 41 Amounts reclassified to investment income (76 ) (183 ) Amounts reclassified to interest expense (29 ) — Balance end of period $ 22,656 $ 1,131 Six months ended June 30, 2018 2017 Balance beginning of period $ 2,619 $ (2,496 ) Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges 19,916 4,016 Amounts reclassified to investment related (gains) losses, net — 41 Amounts reclassified to investment income (221 ) (430 ) Amounts reclassified to interest expense 342 — Balance end of period $ 22,656 $ 1,131
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 six months ended June 30, 2018 and 2017 (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 Interest Expense For the three months ended June 30, 2018: Interest rate $ 4,742 $ — $ — $ 29 Currency/Interest rate (2,643 ) — 76 — Total $ 2,099 $ — $ 76 $ 29 For the three months ended June 30, 2017: Interest rate $ (7,643 ) $ — $ — $ — Currency/Interest rate 1,226 — 132 — Forward bond purchase commitments — (41 ) 51 — Total $ (6,417 ) $ (41 ) $ 183 $ — For the six months ended June 30, 2018: Interest rate $ 19,727 $ — $ — $ (342 ) Currency/Interest rate 189 — 221 — Total $ 19,916 $ — $ 221 $ (342 ) For the six months ended June 30, 2017: Interest rate $ (5,427 ) $ — $ — $ — Currency/Interest rate 9,443 — 329 — Forward bond purchase commitments — (41 ) 101 — Total $ 4,016 $ (41 ) $ 430 $ —
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 six months ended June 30, 2018 and 2017 (dollars in thousands): Derivative Gains (Losses) Deferred in AOCI For the three months ended June 30, For the six months ended June 30, Type of NIFO Hedge (1) (2) 2018 2017 2018 2017 Foreign currency swaps $ 8,197 $ (17,919 ) $ 17,002 $ (25,525 ) Foreign currency forwards 11,063 4,158 23,299 4,158 Total $ 19,260 $ (13,761 ) $ 40,301 $ (21,367 ) (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.
Derivatives Not Designated as Hedging Instruments [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 six months ended June 30, 2018 and 2017 is as follows (dollars in thousands): Gain (Loss) for the three months ended June 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2018 2017 Interest rate swaps Investment related gains (losses), net $ (8,600 ) $ 14,289 Financial futures Investment related gains (losses), net (897 ) (6,442 ) Foreign currency forwards Investment related gains (losses), net (262 ) (351 ) CPI swaps Investment related gains (losses), net 1,041 (4 ) Credit default swaps Investment related gains (losses), net 1,084 3,879 Equity options Investment related gains (losses), net (8,007 ) (9,273 ) Longevity swaps Other revenues 2,289 1,981 Mortality swaps Other revenues (799 ) (395 ) Subtotal (14,151 ) 3,684 Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 8,805 15,108 Indexed annuity products Interest credited 6,519 (5,955 ) Variable annuity products Investment related gains (losses), net 15,324 360 Total non-hedging derivatives $ 16,497 $ 13,197 Gain (Loss) for the six months ended June 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2018 2017 Interest rate swaps Investment related gains (losses), net $ (35,171 ) $ 11,677 Financial futures Investment related gains (losses), net (768 ) (19,217 ) Foreign currency forwards Investment related gains (losses), net 61 553 CPI swaps Investment related gains (losses), net 3,227 (9 ) Credit default swaps Investment related gains (losses), net 682 11,237 Equity options Investment related gains (losses), net (5,414 ) (26,462 ) Longevity swaps Other revenues 4,557 3,847 Mortality swaps Other revenues (799 ) (790 ) Subtotal (33,625 ) (19,164 ) Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 22,416 83,810 Indexed annuity products Interest credited 31,870 (22,357 ) Variable annuity products Investment related gains (losses), net 30,109 22,723 Total non-hedging derivatives $ 50,770 $ 65,012
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 June 30, 2018 and December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 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 $ 2,574 $ 152,000 2.7 $ 3,128 $ 162,000 2.9 Subtotal 2,574 152,000 2.7 3,128 162,000 2.9 BBB+/BBB/BBB- Single name credit default swaps 4,092 338,700 2.6 4,469 361,700 2.9 Credit default swaps referencing indices (59 ) 422,600 3.5 (55 ) 422,600 4.0 Subtotal 4,033 761,300 3.1 4,414 784,300 3.5 BB+/BB/BB- Single name credit default swaps (4 ) 15,000 1.2 30 5,000 1.5 Subtotal (4 ) 15,000 1.2 30 5,000 1.5 Total $ 6,603 $ 928,300 3.0 $ 7,572 $ 951,300 3.4 (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 six months ended June 30, 2018 and 2017 are reflected in the following table (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Embedded derivatives in modco or funds withheld arrangements included in investment related gains $ 8,805 $ 15,108 $ 22,416 $ 83,810 After the associated amortization of DAC and taxes, the related amounts included in net income 5,987 2,941 12,836 28,785 Embedded derivatives in variable annuity contracts included in investment related gains 15,324 360 30,109 22,723 After the associated amortization of DAC and taxes, the related amounts included in net income 12,472 3,023 23,598 31,859 Amounts related to embedded derivatives in equity-indexed annuities included in benefits and expenses 6,519 (5,955 ) 31,870 (22,357 ) After the associated amortization of DAC and taxes, the related amounts included in net income 3,966 (6,925 ) 10,503 (28,322 )
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 June 30, 2018 and December 31, 2017 are reflected in the following table (dollars in thousands): June 30, 2018 December 31, 2017 Estimated fair value of derivatives in net asset position $ 172,997 $ 155,714 Cash provided as collateral (1) 9,030 22,221 Securities pledged to counterparties as collateral (2) 57,302 58,156 Cash pledged from counterparties as collateral (3) (194,067 ) (185,900 ) Securities pledged from counterparties as collateral (4) — (862 ) Initial margin for cleared derivatives (2) (57,302 ) (58,156 ) Net amount after application of master netting agreements and collateral $ (12,040 ) $ (8,827 ) Margin account related to exchange-traded futures (5) $ 8,331 $ 6,538 (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 Liab25

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 are summarized below (dollars in thousands): June 30, 2018: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate $ 22,503,507 $ — $ 21,136,353 $ 1,367,154 Canadian government 4,062,843 — 3,490,145 572,698 RMBS 1,821,214 — 1,766,375 54,839 ABS 1,708,824 — 1,638,138 70,686 CMBS 1,242,509 — 1,240,642 1,867 U.S. government 1,525,150 1,405,485 98,930 20,735 State and political subdivisions 737,044 — 720,539 16,505 Other foreign government 3,183,863 — 3,178,819 5,044 Total fixed maturity securities – available-for-sale 36,784,954 1,405,485 33,269,941 2,109,528 Equity securities 108,070 65,133 — 42,937 Funds withheld at interest – embedded derivatives 144,610 — — 144,610 Cash equivalents 424,601 409,242 15,359 — Short-term investments 82,521 991 78,313 3,217 Other invested assets: Derivatives: Interest rate swaps 36,170 — 36,170 — Foreign currency forwards 18,428 — 18,428 — CPI swaps (42 ) — (42 ) — Credit default swaps 5,927 — 5,927 — Equity options 21,136 — 21,136 — Foreign currency swaps 55,696 — 55,696 — FVO contractholder-directed unit-linked investments 212,202 211,141 1,061 — Total other invested assets 349,517 211,141 138,376 — Other assets - longevity swaps 43,971 — — 43,971 Total $ 37,938,244 $ 2,091,992 $ 33,501,989 $ 2,344,263 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 928,797 $ — $ — $ 928,797 Other liabilities: Derivatives: Interest rate swaps 14,740 — 14,740 — Foreign currency forwards 8 — 8 — CPI swaps (969 ) — (969 ) — Credit default swaps (676 ) — (676 ) — Equity options (4,814 ) — (4,814 ) — Mortality swaps 782 — — 782 Total $ 937,868 $ — $ 8,289 $ 929,579 December 31, 2017: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate $ 23,210,968 $ — $ 21,873,696 $ 1,337,272 Canadian government 4,220,076 — 3,626,134 593,942 RMBS 1,719,880 — 1,611,998 107,882 ABS 1,648,362 — 1,524,888 123,474 CMBS 1,303,387 — 1,300,153 3,234 U.S. government 1,943,592 1,818,006 103,075 22,511 State and political subdivisions 703,428 — 662,225 41,203 Other foreign government 3,401,127 — 3,396,035 5,092 Total fixed maturity securities – available-for-sale 38,150,820 1,818,006 34,098,204 2,234,610 Equity securities: Non-redeemable preferred stock 39,806 39,806 — — Other equity securities 60,346 60,346 — — Funds withheld at interest – embedded derivatives 122,194 — — 122,194 Cash equivalents 356,788 354,071 2,717 — Short-term investments 50,746 — 47,650 3,096 Other invested assets: Derivatives: Interest rate swaps 51,359 — 51,359 — Foreign currency forwards 730 — 730 — CPI swaps (221 ) — (221 ) — Credit default swaps 5,908 — 5,908 — Equity options 16,932 — 16,932 — Foreign currency swaps 62,905 — 62,905 — FVO contractholder-directed unit-linked investments 218,541 217,618 923 — Total other invested assets 356,154 217,618 138,536 — Other assets - longevity swaps 40,659 — — 40,659 Total $ 39,177,513 $ 2,489,847 $ 34,287,107 $ 2,400,559 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 1,014,228 $ — $ — $ 1,014,228 Other liabilities: Derivatives: Interest rate swaps 14,311 — 14,311 — Foreign currency forwards 7,213 — 7,213 — CPI swaps 1,939 — 1,939 — Credit default swaps (760 ) — (760 ) — Equity options (6,339 ) — (6,339 ) — Foreign currency swaps 6,194 — 6,194 — Mortality swaps 1,683 — — 1,683 Total $ 1,038,469 $ — $ 22,558 $ 1,015,911
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 six months ended June 30, 2017 (dollars in thousands): 2017 Transfers from Level 1 to Level 2 Transfers from Level 2 to Level 1 Three months ended June 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ 49,999 Six months ended June 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ 88,674
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 June 30, 2018 and December 31, 2017 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) June 30, 2018 December 31, 2017 June 30, 2018 December 31, 2017 Assets: Corporate $ 571,750 $ 173,579 Market comparable securities Liquidity premium 0-2% (1%) 0-2% (1%) EBITDA Multiple 5.9x-7.5x (6.9x) — U.S. government 20,735 22,511 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions 4,361 4,616 Market comparable securities Liquidity premium 1 % 1 % Other foreign government 5,044 — Market comparable securities Liquidity premium 1 % — Equity securities 23,856 — Market comparable securities Liquidity premium 1 % — EBITDA Multiple 6.9x-13.1x (7.9x) — Funds withheld at interest- embedded derivatives 144,610 122,194 Total return swap Mortality 0-100% (2%) 0-100% (2%) Lapse 0-35% (9%) 0-35% (9%) Withdrawal 0-5% (3%) 0-5% (3%) CVA 0-5% (1%) 0-5% (1%) Crediting rate 2-4% (2%) 2-4% (2%) Longevity swaps 43,971 40,659 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 806,436 861,758 Discounted cash flow Mortality 0-100% (2%) 0-100% (2%) Lapse 0-35% (9%) 0-35% (9%) Withdrawal 0-5% (3%) 0-5% (3%) Option budget projection 2-4% (2%) 2-4% (2%) Interest sensitive contract liabilities- embedded derivatives- variable annuities 122,361 152,470 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%) Lapse 0-25% (5%) 0-25% (5%) Withdrawal 0-7% (4%) 0-7% (3%) CVA 0-5% (1%) 0-5% (1%) Long-term volatility 0-27% (14%) 0-27% (8%) Mortality swaps 782 1,683 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%) 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 June 30, 2018 and December 31, 2017 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) June 30, 2018 December 31, 2017 June 30, 2018 December 31, 2017 Assets: Corporate $ 571,750 $ 173,579 Market comparable securities Liquidity premium 0-2% (1%) 0-2% (1%) EBITDA Multiple 5.9x-7.5x (6.9x) — U.S. government 20,735 22,511 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions 4,361 4,616 Market comparable securities Liquidity premium 1 % 1 % Other foreign government 5,044 — Market comparable securities Liquidity premium 1 % — Equity securities 23,856 — Market comparable securities Liquidity premium 1 % — EBITDA Multiple 6.9x-13.1x (7.9x) — Funds withheld at interest- embedded derivatives 144,610 122,194 Total return swap Mortality 0-100% (2%) 0-100% (2%) Lapse 0-35% (9%) 0-35% (9%) Withdrawal 0-5% (3%) 0-5% (3%) CVA 0-5% (1%) 0-5% (1%) Crediting rate 2-4% (2%) 2-4% (2%) Longevity swaps 43,971 40,659 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 806,436 861,758 Discounted cash flow Mortality 0-100% (2%) 0-100% (2%) Lapse 0-35% (9%) 0-35% (9%) Withdrawal 0-5% (3%) 0-5% (3%) Option budget projection 2-4% (2%) 2-4% (2%) Interest sensitive contract liabilities- embedded derivatives- variable annuities 122,361 152,470 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%) Lapse 0-25% (5%) 0-25% (5%) Withdrawal 0-7% (4%) 0-7% (3%) CVA 0-5% (1%) 0-5% (1%) Long-term volatility 0-27% (14%) 0-27% (8%) Mortality swaps 782 1,683 Discounted cash flow Mortality 0-100% (1%) 0-100% (1%)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	The reconciliations for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) are as follows (dollars in thousands): For the three months ended June 30, 2018: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,299,264 $ 572,747 $ 120,614 $ 130,706 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (305 ) 3,468 (43 ) 76 Investment related gains (losses), net (3,141 ) — 312 1,282 Included in other comprehensive income 2,178 (3,517 ) (671 ) (1,544 ) Purchases (1) 155,498 — 24,412 — Sales (1) (11,089 ) — (4,961 ) — Settlements (1) (68,328 ) — (1,572 ) (19,544 ) Transfers into Level 3 — — 3,031 4,968 Transfers out of Level 3 (6,923 ) — (86,283 ) (45,258 ) Fair value, end of period $ 1,367,154 $ 572,698 $ 54,839 $ 70,686 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 $ (304 ) $ 3,468 $ (13 ) $ 68 Investment related gains (losses), net (3,141 ) — — — For the three months ended June 30, 2018 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 1,884 $ 21,053 $ 41,876 $ 5,004 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (107 ) (10 ) — Included in other comprehensive income (16 ) (173 ) (110 ) 40 Purchases (1) — 118 — — Settlements (1) (2 ) (156 ) (86 ) — Transfers out of Level 3 1 — (25,165 ) — Fair value, end of period $ 1,867 $ 20,735 $ 16,505 $ 5,044 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 $ — $ (108 ) $ (11 ) $ — For the three months ended June 30, 2018 (continued): Equity securities Funds withheld at interest- embedded derivatives Short-term Investments Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 36,152 $ 135,805 $ 3,217 $ 44,011 $ (964,794 ) $ (1,683 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — — — — — — Investment related gains (losses), net (4,922 ) 8,805 — — 15,324 — Claims & other policy benefits — — — — — — Interest credited — — — — 6,519 — Policy acquisition costs and other insurance expenses — — — — — — Included in other comprehensive income — — (21 ) (2,329 ) — — Other revenues — — — 2,289 — (799 ) Purchases (1) 12,248 — 335 — (4,205 ) — Sales (1) (541 ) — — — — — Settlements (1) — — (314 ) — 18,359 1,700 Transfers into Level 3 — — — — — — Transfers out of Level 3 — — — — — — Fair value, end of period $ 42,937 $ 144,610 $ 3,217 $ 43,971 $ (928,797 ) $ (782 ) 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 $ (5,000 ) $ 8,805 $ — $ — $ 13,474 $ — Other revenues — — — 2,289 — (799 ) Interest credited — — — — (11,839 ) — For the six months ended June 30, 2018: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,337,272 $ 593,942 $ 107,882 $ 123,474 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (666 ) 6,912 (135 ) 182 Investment related gains (losses), net (3,141 ) — 312 1,284 Included in other comprehensive income (30,674 ) (28,156 ) (1,781 ) (691 ) Purchases (1) 255,668 — 45,328 11,000 Sales (1) (17,269 ) — (4,961 ) — Settlements (1) (143,474 ) — (4,535 ) (22,283 ) Transfers into Level 3 7,166 — 3,031 4,968 Transfers out of Level 3 (37,728 ) — (90,302 ) (47,248 ) Fair value, end of period $ 1,367,154 $ 572,698 $ 54,839 $ 70,686 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 $ (665 ) $ 6,912 $ (105 ) $ 174 Investment related gains (losses), net (3,141 ) — — — For the six months ended June 30, 2018 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 3,234 $ 22,511 $ 41,203 $ 5,092 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (217 ) (2 ) — Included in other comprehensive income (63 ) (513 ) 590 (48 ) Purchases (1) — 214 — — Settlements (1) (3 ) (1,260 ) (121 ) — Transfers out of Level 3 (1,301 ) — (25,165 ) — Fair value, end of period $ 1,867 $ 20,735 $ 16,505 $ 5,044 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 $ — $ (218 ) $ (3 ) $ — For the six months ended June 30, 2018 (continued): Equity securities Funds withheld at interest- embedded derivatives Short-term Investments Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ — $ 122,194 $ 3,096 $ 40,659 $ (1,014,228 ) $ (1,683 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net (7,599 ) 22,416 — — 30,109 — Interest credited — — — — 31,870 — Included in other comprehensive income — — (46 ) (1,245 ) — — Other revenues — — — 4,557 — (799 ) Purchases (1) 12,248 — 481 — (12,713 ) — Sales (1) (569 ) — — — — — Settlements (1) (48 ) — (314 ) — 36,165 1,700 Transfers into Level 3 38,905 — — — — — Fair value, end of period $ 42,937 $ 144,610 $ 3,217 $ 43,971 $ (928,797 ) $ (782 ) 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 $ (7,705 ) $ 22,416 $ — $ — $ 26,375 $ — Other revenues — — — 4,557 — (799 ) Interest credited — — — — (4,295 ) — For the three months ended June 30, 2017: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,263,925 $ 483,560 $ 143,430 $ 208,436 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (396 ) 3,201 (29 ) 511 Investment related gains (losses), net 8,427 — 115 — Included in other comprehensive income (4,548 ) 46,509 1,962 1,136 Purchases (1) 104,087 — 29,318 34,366 Sales (1) (23,174 ) — (4,467 ) — Settlements (1) (74,531 ) — (4,655 ) (27,569 ) Transfers into Level 3 17,264 — 5,423 3,500 Transfers out of Level 3 — — (22,412 ) (18,791 ) Fair value, end of period $ 1,291,054 $ 533,270 $ 148,685 $ 201,589 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 $ (396 ) $ 3,201 $ (37 ) $ 239 Investment related gains (losses), net (1,495 ) — — — For the three months ended June 30, 2017 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 1,923 $ 23,474 $ 33,858 $ 12,344 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (115 ) (6 ) — Included in other comprehensive income 21 211 823 (12 ) Purchases (1) — 132 — — Settlements (1) (1 ) (135 ) (241 ) (338 ) Fair value, end of period $ 1,943 $ 23,567 $ 34,434 $ 11,994 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 $ — $ (115 ) $ (6 ) $ — For the three months ended June 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 $ 3,276 $ 46,173 $ 29,170 $ (972,930 ) $ (2,857 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 15,108 — 360 — Interest credited — — — (5,955 ) — Included in other comprehensive income (29 ) — 2,198 — — Other revenues — — 1,981 — (395 ) Purchases (1) 324 — — (19,533 ) — Settlements (1) (23 ) — — 23,427 1,700 Fair value, end of period $ 3,548 $ 61,281 $ 33,349 $ (974,631 ) $ (1,552 ) 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 $ — $ 15,108 $ — $ (1,794 ) $ — Other revenues — — 1,981 — (395 ) Interest credited — — — (29,382 ) — For the six months ended June 30, 2017: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS 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 (819 ) 6,271 (274 ) 1,529 Investment related gains (losses), net 7,196 — 480 — Included in other comprehensive income 400 51,034 2,612 6,903 Purchases (1) 150,001 — 45,817 45,215 Sales (1) (23,174 ) — (15,071 ) — Settlements (1) (146,001 ) — (11,439 ) (45,723 ) Transfers into Level 3 31,198 — 5,500 38,758 Transfers out of Level 3 — — (39,231 ) (64,373 ) Fair value, end of period $ 1,291,054 $ 533,270 $ 148,685 $ 201,589 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 $ (819 ) $ 6,271 $ (128 ) $ 400 Investment related gains (losses), net (2,788 ) — (346 ) — For the six months ended June 30, 2017 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government 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 (232 ) (94 ) — Investment related gains (losses), net (595 ) — — — Included in other comprehensive income (62 ) 263 (20 ) (203 ) Purchases (1) — 236 — — Sales (1) (3,720 ) — — — Settlements (1) (5,402 ) (1,188 ) (274 ) (672 ) Transfers out of Level 3 (10,132 ) — (6,844 ) — Fair value, end of period $ 1,943 $ 23,567 $ 34,434 $ 11,994 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 $ — $ (232 ) $ (94 ) $ — For the six months ended June 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 — 83,810 — 22,723 — Interest credited — — — (22,357 ) — Included in other comprehensive income 4 — 2,545 — — Other revenues — — 3,846 — (790 ) Purchases (1) 356 — — (25,927 ) — Settlements (1) (158 ) — — 41,238 1,700 Fair value, end of period $ 3,548 $ 61,281 $ 33,349 $ (974,631 ) $ (1,552 ) 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 $ — $ 83,810 $ — $ 18,505 $ — Other revenues — — 3,846 — (790 ) Interest credited — — — (63,596 ) — (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 2017 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) (dollars in thousands) At June 30, 2017 Three months ended June 30, 2017 Six months ended June 30, 2017 Limited partnership interests (1) $ 3,690 $ (6,308 ) $ (6,308 ) (1) 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.
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 June 30, 2018 and December 31, 2017 (dollars in thousands). For additional information regarding the methods and significant assumptions used by the Company to estimate these fair values, see Note 6 in the Notes to Consolidated Financial Statements included in the Company’s 2017 Annual Report. 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. June 30, 2018: Carrying Value (1) Estimated Fair Value Fair Value Measurement Using: Level 1 Level 2 Level 3 NAV Assets: Mortgage loans on real estate $ 4,558,669 $ 4,461,317 $ — $ — $ 4,461,317 $ — Policy loans 1,339,252 1,339,252 — 1,339,252 — — Funds withheld at interest 5,836,373 6,057,217 — — 6,057,217 — Cash and cash equivalents 973,078 973,078 973,078 — — — Short-term investments 40,507 40,507 40,507 — — — Other invested assets 757,264 775,322 5,565 71,797 323,142 374,818 Accrued investment income 400,160 400,160 — 400,160 — — Liabilities: Interest-sensitive contract liabilities $ 13,072,239 $ 12,972,203 $ — $ — $ 12,972,203 $ — Long-term debt 2,788,111 2,868,837 — — 2,868,837 — Collateral finance and securitization notes 724,998 666,356 — — 666,356 — December 31, 2017: Carrying Value (1) Estimated Fair Value Fair Value Measurement Using: Level 1 Level 2 Level 3 NAV Assets: Mortgage loans on real estate $ 4,400,533 $ 4,477,654 $ — $ — $ 4,477,654 $ — Policy loans 1,357,624 1,357,624 — 1,357,624 — — Funds withheld at interest 5,955,092 6,275,623 — — 6,275,623 — Cash and cash equivalents 946,736 946,736 946,736 — — — Short-term investments 42,558 42,558 42,558 — — — Other invested assets 651,792 679,377 28,540 67,778 247,934 335,125 Accrued investment income 392,721 392,721 — 392,721 — — Liabilities: Interest-sensitive contract liabilities $ 12,683,872 $ 12,917,243 $ — $ — $ 12,917,243 $ — Long-term debt 2,788,365 2,959,912 — — 2,959,912 — Collateral finance and securitization notes 783,938 722,145 — — 722,145 — (1) Carrying values presented herein may differ from those in the Company’s condensed consolidated balance sheets because certain items within the respective financial statement captions may be measured at fair value on a recurring basis.

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, Six months ended June 30, Revenues: 2018 2017 2018 2017 U.S. and Latin America: Traditional $ 1,564,147 $ 1,522,698 $ 3,053,841 $ 3,011,201 Financial Solutions 229,948 271,976 443,300 570,822 Total 1,794,095 1,794,674 3,497,141 3,582,023 Canada: Traditional 312,199 269,273 614,518 533,548 Financial Solutions 12,089 12,003 24,866 23,810 Total 324,288 281,276 639,384 557,358 Europe, Middle East and Africa: Traditional 372,538 345,920 766,320 664,006 Financial Solutions 100,675 73,405 188,818 153,394 Total 473,213 419,325 955,138 817,400 Asia Pacific: Traditional 570,520 561,529 1,185,059 1,066,759 Financial Solutions 17,992 17,984 37,838 38,436 Total 588,512 579,513 1,222,897 1,105,195 Corporate and Other 15,800 54,488 55,055 76,040 Total $ 3,195,908 $ 3,129,276 $ 6,369,615 $ 6,138,016
Reconciliation Of Operating Profit Loss From Segments To Consolidated Text Block	Three months ended June 30, Six months ended June 30, Income (loss) before income taxes: 2018 2017 2018 2017 U.S. and Latin America: Traditional $ 71,978 $ 90,594 $ 74,870 $ 120,554 Financial Solutions 82,388 106,985 149,809 210,571 Total 154,366 197,579 224,679 331,125 Canada: Traditional 21,805 32,836 45,512 52,164 Financial Solutions 3,544 4,425 6,735 8,017 Total 25,349 37,261 52,247 60,181 Europe, Middle East and Africa: Traditional 6,468 11,354 21,889 25,330 Financial Solutions 65,369 28,905 104,533 60,823 Total 71,837 40,259 126,422 86,153 Asia Pacific: Traditional 58,862 53,322 81,749 95,010 Financial Solutions 4,138 5,377 8,159 11,249 Total 63,000 58,699 89,908 106,259 Corporate and Other (67,264 ) 5,517 (108,043 ) (36,559 ) Total $ 247,288 $ 339,315 $ 385,213 $ 547,159
Reconciliation Of Assets From Segment To Consolidated Text Block	Assets: June 30, 2018 December 31, 2017 U.S. and Latin America: Traditional $ 19,038,145 $ 18,603,423 Financial Solutions 16,043,393 15,959,206 Total 35,081,538 34,562,629 Canada: Traditional 4,203,344 4,161,452 Financial Solutions 141,581 126,372 Total 4,344,925 4,287,824 Europe, Middle East and Africa: Traditional 3,335,264 3,099,495 Financial Solutions 4,829,194 5,274,993 Total 8,164,458 8,374,488 Asia Pacific: Traditional 5,159,546 4,915,442 Financial Solutions 1,156,371 1,198,585 Total 6,315,917 6,114,027 Corporate and Other 5,859,659 7,175,850 Total $ 59,766,497 $ 60,514,818

Commitments, Contingencies an27

Commitments, Contingencies and Guarantees (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 are presented in the following table (dollars in thousands): June 30, 2018 December 31, 2017 Limited partnership interests and joint ventures $ 490,601 $ 485,197 Commercial mortgage loans 113,992 40,815 Bank loans and private placements 98,652 60,472 Equity release mortgages 157,069 153,937
Other Commitments [Table Text Block]	The following table presents the maximum potential obligation for these commitments as of June 30, 2018 (dollars in millions): Commitment Period: Maximum Potential Obligation 2023 $ 500.0 2033 450.0 2034 2,000.0 2035 1,314.2 2036 1,932.0 2037 6,750.0 2038 800.0
Schedule of Guarantor Obligations [Table Text Block]	RGA’s guarantees issued as of June 30, 2018 and December 31, 2017 are reflected in the following table (dollars in thousands): June 30, 2018 December 31, 2017 Treaty guarantees $ 913,902 $ 1,047,449 Treaty guarantees, net of assets in trust 802,073 926,393 Securities borrowing and repurchase arrangements 289,210 294,325 Financing arrangements 74,864 86,183 Lease obligations 1,137 1,662

Income Tax (Tables)

Income Tax (Tables)	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	three and six months ended June 30, 2018 and 2017 , respectively (dollars in thousands): Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Tax provision at U.S. statutory rate $ 51,931 $ 118,760 $ 80,895 $ 191,506 Increase (decrease) in income taxes resulting from: U.S. Tax Reform provisional adjustments (4,314 ) — (3,539 ) — Foreign tax rate differing from U.S. tax rate (330 ) (4,261 ) 1,103 (10,413 ) Differences in tax bases in foreign jurisdictions (1,132 ) (13,375 ) (6,892 ) (16,759 ) Deferred tax valuation allowance 3,079 13,031 10,501 14,213 Amounts related to tax audit contingencies (2,036 ) (1,783 ) (1,201 ) (1,172 ) Corporate rate changes 145 44 417 (1,193 ) Subpart F (348 ) 1,140 310 1,326 Foreign tax credits 113 (1,938 ) (459 ) (2,064 ) Global intangible low-taxed income, net of credit (119 ) — 4,291 — Equity compensation excess benefit (3,135 ) (2,609 ) (4,250 ) (4,464 ) Return to provision adjustments (503 ) (633 ) (139 ) (403 ) Other, net (437 ) (1,251 ) (428 ) (1,120 ) Total provision for income taxes $ 42,914 $ 107,125 $ 80,609 $ 169,457 Effective tax rate 17.4 % 31.6 % 20.9 % 31.0 %

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2018
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 six months ended June 30, 2018 and 2017 were as follows (dollars in thousands): Pension Benefits Other Benefits Three months ended June 30, Three months ended June 30, 2018 2017 2018 2017 Service cost $ 3,570 $ 2,819 $ 636 $ 721 Interest cost 1,357 1,431 529 565 Expected return on plan assets (2,213 ) (1,823 ) — — Amortization of prior service cost (credit) 82 95 (329 ) (155 ) Amortization of prior actuarial losses 769 1,082 498 457 Settlements — 256 — — Net periodic benefit cost $ 3,565 $ 3,860 $ 1,334 $ 1,588 Pension Benefits Other Benefits Six months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Service cost $ 6,224 $ 5,399 $ 1,272 $ 1,442 Interest cost 2,687 2,629 1,059 1,130 Expected return on plan assets (3,767 ) (3,108 ) — — Amortization of prior service cost (credit) 165 169 (658 ) (311 ) Amortization of prior actuarial losses 1,863 2,163 996 914 Settlements — 513 — — Net periodic benefit cost $ 7,172 $ 7,765 $ 2,669 $ 3,175

Reinsurance (Tables)

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 or December 31, 2017 (dollars in thousands): June 30, 2018 December 31, 2017 Reinsurer A.M. Best Rating Amount % of Total Amount % of Total Reinsurer A A+ $ 312,405 39.6 $ 301,478 38.6 % Reinsurer B A+ 198,782 25.2 203,898 26.1 Reinsurer C A 67,699 8.6 67,723 8.7 Reinsurer D A+ 41,807 5.3 40,528 5.2 Reinsurer E A++ 38,935 4.9 40,592 5.2 Other reinsurers 129,801 16.4 127,808 16.2 Total $ 789,429 100.0 % $ 782,027 100.0 %

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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Net income (numerator for basic and diluted calculations)	$ 204,374	$ 232,190	$ 304,604	$ 377,702
Shares:
Weighted average outstanding shares (denominator for basic calculation)	64,071	64,449	64,278	64,401
Equivalent shares from outstanding stock options	1,179	1,159	1,277	1,204
Denominator for diluted calculation	65,250	65,608	65,555	65,605
Earnings Per Share:
Basic earnings per share	$ 3.19	$ 3.60	$ 4.74	$ 5.86
Diluted earnings per share	$ 3.13	$ 3.54	$ 4.65	$ 5.76

Earnings Per Share (Stock Optio

Earnings Per Share (Stock Options and Performance Shares Excluded From Common Equivalent Shares) (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.2	0.2	0.3	0.3
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	0.2	0.3	0.2	0.3

Equity (Common Stock Changes In

Equity (Common Stock Changes In Number of Shares Issued, Held In Treasury and Outstanding) (Details) - shares		3 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common Stock, Shares, Issued		79,137,758		79,137,758
Treasury Stock, Shares, Acquired		1,000,000
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
Stock Based Compensation Shares	[1]	0	0
Common Stock Held In Treasury [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		15,465,272	14,645,901	14,685,663	14,835,256
Treasury Stock, Shares, Acquired		991,477
Stock Based Compensation Shares	[1]	(211,868)	(189,355)
Common Stock Outstanding [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		63,672,486	64,491,857	64,452,095	64,302,502
Treasury Stock, Shares, Acquired		(991,477)
Stock Based Compensation Shares	[1]	(211,868)	(189,355)
[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		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Accumulated other comprehensive income		$ 1,004,971	$ 1,671,898	$ 2,063,631	$ 1,139,329
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(1,374,408)	760,556
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		56,012	(36,425)
Other Comprehensive Income (Loss), Tax		(259,736)	191,562
Accumulated Translation Adjustment [Member]
Accumulated other comprehensive income		(142,187)	(151,189)	(86,350)	(172,541)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(44,227)	(13,936)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		0	0
Other Comprehensive Income (Loss), Tax		(11,610)	35,288
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated other comprehensive income	[1]	1,198,338	1,864,477	2,200,661	1,355,033
Other Comprehensive Income (Loss), before Reclassifications, before Tax	[1]	(1,327,195)	774,688
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	[1]	53,646	(39,360)
Other Comprehensive Income (Loss), Tax	[1]	(271,226)	225,884
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated other comprehensive income		(51,180)	(41,390)	$ (50,680)	$ (43,163)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(2,986)	(196)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		2,366	2,935
Other Comprehensive Income (Loss), Tax		$ (120)	$ 966
[1]	Includes cash flow hedges of $22,656 and $2,619 as of June 30, 2018 and December 31, 2017, respectively, and $1,131 and $(2,496) as of June 30, 2017 and December 31, 2016, respectively. See Note 5 - “Derivative Instruments” for additional information on cash flow hedges.

Equity (Balance of and Change35

Equity (Balance of and Changes in Each Component of AOCI) (Footnote) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2016	Mar. 31, 2015	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 22,656	$ 1,131	$ 20,662	$ 7,690	$ 22,656	$ 1,131	$ 2,619	$ (2,496)

Equity (Schedule of Reclassific

Equity (Schedule of Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		$ (7,222)		$ 59,696		$ (7,692)		$ 137,408
Investment income		528,061		518,538		1,044,390		1,032,902
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		247,288		339,315		385,213		547,159
Income Tax Expense (Benefit)		(42,914)		(107,125)		(80,609)		(169,457)
Net income		204,374		232,190		304,604		377,702
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		(32,372)		45,122		(53,646)		39,360
Income Tax Expense (Benefit)		6,945		(15,218)		11,623		(12,024)
Net income		(25,427)		29,904		(42,023)		27,336
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		(24,642)		40,374		(39,098)		28,517
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]	29		0		(342)		0
Unrealized Appreciation Depreciation Of Investments [Member] | Currency 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]	76		132		221		329
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]	0		51		0		101
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		(7,835)	[1]	4,565	[1]	14,427	[2]	10,413	[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		(1,020)		(1,479)		(2,366)		(2,935)
Income Tax Expense (Benefit)		214		517		497		1,027
Net income		(806)		(962)		(1,869)		(1,908)
Amounts Reclassified From AOCI [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		(26,233)		28,942		(43,892)		25,428
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		247	[2]	60	[2]	493	[3]	142	[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)		$ (1,267)	[2]	$ (1,539)	[2]	$ 2,859	[3]	$ (3,077)	[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 2017 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	6 Months Ended
	Jun. 30, 2018USD ($)shares	Jun. 30, 2018USD ($)
Equity [Abstract]
Stock Repurchase Program, Authorized Amount	$ 400	$ 400
Treasury Stock, Shares, Acquired | shares	1
Treasury Stock, Value, Acquired, Cost Method		$ 150

Equity Based Compensation (Narr

Equity Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity compensation expense	$ 16.6	$ 11.4
Stock appreciation rights granted	200,000
Stock appreciation rights granted, weighted average exercise price (per share)	$ 150.87
Performance contingent units	100,000
Shares Granted To Non Employee Directors	7,623
Options exercisable (shares)	1,500,000
Options exercisable, weighted average price (per share)	$ 65.70
Options, remaining term	4 years 5 months
Compensation cost not yet recognized	$ 36.9
Period for recognition	1 year 5 months

Investments (Investments in Fix

Investments (Investments in Fixed Maturity and Equity Securities Available-for-Sale by Sector) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 22,249,964	$ 21,966,803
Estimated Fair Value	$ 22,503,507	$ 23,210,968
% of Total	100.00%	100.00%
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 35,233,970	$ 35,281,412
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2,143,192	2,982,754
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	592,208	113,346
Estimated Fair Value	$ 36,784,954	$ 38,150,820
% of Total	100.00%	100.00%
Other-than-temporary impairments in AOCI	$ 275	$ 275
Equity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		102,841
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		958
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		3,647
Estimated Fair Value		$ 100,152
% of Total		100.00%
Corporate Debt Securities [Member] | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	22,249,964	$ 21,966,803
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	663,087	1,299,594
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	409,544	55,429
Estimated Fair Value	$ 22,503,507	$ 23,210,968
% of Total	61.20%	60.90%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Canadian and Canadian provincial governments | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,789,699	2,843,273
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,277,020	1,378,510
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	3,876	1,707
Estimated Fair Value	$ 4,062,843	$ 4,220,076
% of Total	11.00%	11.10%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Residential mortgage-backed securities | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,837,316	1,695,126
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	18,500	36,632
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	34,602	11,878
Estimated Fair Value	$ 1,821,214	$ 1,719,880
% of Total	5.00%	4.50%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Asset-backed securities | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,711,099	1,634,758
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	11,596	18,798
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	13,871	5,194
Estimated Fair Value	$ 1,708,824	$ 1,648,362
% of Total	4.60%	4.30%
Other-than-temporary impairments in AOCI	$ 275	$ 275
Commercial Mortgage Backed Securities [Member] | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,249,616	1,285,594
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	8,591	22,627
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	15,698	4,834
Estimated Fair Value	$ 1,242,509	$ 1,303,387
% of Total	3.40%	3.40%
Other-than-temporary impairments in AOCI	$ 0	$ 0
US Treasury and Government [Member] | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,583,622	1,953,436
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	8,193	12,089
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	66,665	21,933
Estimated Fair Value	$ 1,525,150	$ 1,943,592
% of Total	4.10%	5.10%
Other-than-temporary impairments in AOCI	$ 0	$ 0
US States and Political Subdivisions Debt Securities [Member] | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	703,047	647,727
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	43,318	59,997
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	9,321	4,296
Estimated Fair Value	$ 737,044	$ 703,428
% of Total	2.00%	1.80%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Debt Security, Government, Non-US [Member] | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,109,607	3,254,695
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	112,887	154,507
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	38,631	8,075
Estimated Fair Value	$ 3,183,863	$ 3,401,127
% of Total	8.70%	8.90%
Other-than-temporary impairments in AOCI	$ 0	$ 0
Nonredeemable Preferred Stock [Member] | Equity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		41,553
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		479
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		2,226
Estimated Fair Value		$ 39,806
% of Total		39.70%
Other equity securities | Equity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		$ 61,288
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		479
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		1,421
Estimated Fair Value		$ 60,346
% of Total		60.30%

Investments (Fixed Maturity Sec

Investments (Fixed Maturity Securities Pledged And Received As Collateral) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 22,249,964	$ 21,966,803
Available-for-sale Securities	22,503,507	23,210,968
Collateral Fixed Maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	63,640	72,542
Available-for-sale Securities	66,118	75,622
Collateral Received Fixed Maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities	626,081	590,417
Reported Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held-in-trust	16,061,218	15,584,296
Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held-in-trust	$ 16,571,173	$ 16,715,281

Investments (Exposure To Concen

Investments (Exposure To Concentrations Of Credit Risk) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 22,249,964	$ 21,966,803
Available-for-sale Securities	22,503,507	23,210,968
Canadian Province Of Quebec Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	929,913	939,837
Available-for-sale Securities	1,239,102	1,282,944
Canadian Province Of Ontario Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,101,825	1,119,337
Available-for-sale Securities	$ 1,850,642	$ 1,917,996

Investments (Amortized Cost and

Investments (Amortized Cost and Fair Value of Fixed Maturities by Contractual Maturities) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Available For Sale Securities Debt Maturities Amortized Cost
Due in one year or less	$ 978,683
Due after one year through five years	7,550,595
Due after five year through ten years	9,208,763
Due after ten years	12,697,898
Asset and mortgage-backed securities	4,798,031
Total	35,233,970	$ 30,211,787
Available For Sale Securities Debt Maturities Fair Value
Due in one year or less	986,160
Due after one year through five years	7,649,023
Due after five year through ten years	9,323,786
Due after ten years	14,053,438
Asset and mortgage-backed securities	4,772,547
Total	$ 36,784,954	$ 38,150,820

Investments (Amortized Cost a43

Investments (Amortized Cost and Fair Value of Fixed Maturity Holdings by Industry Type) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 22,249,964	$ 21,966,803
Estimated Fair Value	$ 22,503,507	$ 23,210,968
% of Total	100.00%	100.00%
Financial Services Sector [Member]
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 8,097,947	$ 7,977,885
Estimated Fair Value	$ 8,129,125	$ 8,362,774
% of Total	36.20%	36.10%
Commercial and Industrial Sector [Member]
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 11,705,150	$ 11,535,166
Estimated Fair Value	$ 11,847,762	$ 12,199,333
% of Total	52.60%	52.50%
Utility Sector [Member]
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 2,446,867	$ 2,453,752
Estimated Fair Value	$ 2,526,620	$ 2,648,861
% of Total	11.20%	11.40%

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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance, beginning of period	$ 3,677	$ 3,677	$ 3,677	$ 6,013
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Change in Status	0	0	0	(2,336)
Balance, end of period	$ 3,677	$ 3,677	$ 3,677	$ 3,677

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	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 592,208	$ 116,993
% of Total	100.00%	100.00%
Less than 20%
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 571,151	$ 113,466
% of Total	96.40%	97.00%
20% or more for less than six months
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 21,045	$ 689
% of Total	3.60%	0.60%
20% or more for six months or greater
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 12	$ 2,838
% of Total	0.00%	2.40%

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	Jun. 30, 2018	Dec. 31, 2017
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	$ 14,260,261	$ 4,565,273
Gross Unrealized Losses - Less than 12 months	454,493	40,239
Estimated Fair Value - 12 months or greater	2,494,303	2,738,393
Gross Unrealized Losses - 12 months or greater	137,715	73,107
Estimated Fair Value	16,754,564	7,303,666
Gross Unrealized Losses	592,208	113,346
Equity securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Estimated Fair Value - Less than 12 months		5,902
Gross Unrealized Losses - Less than 12 months		1,024
Estimated Fair Value - 12 months or greater		73,722
Gross Unrealized Losses - 12 months or greater		2,623
Estimated Fair Value		79,624
Gross Unrealized Losses		3,647
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	883,576	225,474
Gross Unrealized Losses - Less than 12 months	55,107	3,450
Estimated Fair Value - 12 months or greater	66,027	93,723
Gross Unrealized Losses - 12 months or greater	10,277	7,559
Estimated Fair Value	949,603	319,197
Gross Unrealized Losses	65,384	11,009
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	13,376,685	4,339,799
Gross Unrealized Losses - Less than 12 months	399,386	36,789
Estimated Fair Value - 12 months or greater	2,428,276	2,644,670
Gross Unrealized Losses - 12 months or greater	127,438	65,548
Estimated Fair Value	15,804,961	6,984,469
Gross Unrealized Losses	526,824	102,337
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	735,338	194,879
Gross Unrealized Losses - Less than 12 months	47,846	3,317
Estimated Fair Value - 12 months or greater	56,042	75,731
Gross Unrealized Losses - 12 months or greater	9,851	6,933
Estimated Fair Value	791,380	270,610
Gross Unrealized Losses	57,697	10,250
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	9,135,620	1,886,212
Gross Unrealized Losses - Less than 12 months	299,909	17,099
Estimated Fair Value - 12 months or greater	818,555	1,009,750
Gross Unrealized Losses - 12 months or greater	51,938	28,080
Estimated Fair Value	9,954,175	2,895,962
Gross Unrealized Losses	351,847	45,179
Canadian and Canadian provincial governments | 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	1,864	1,995
Gross Unrealized Losses - Less than 12 months	150	20
Estimated Fair Value - 12 months or greater	0	0
Gross Unrealized Losses - 12 months or greater	0	0
Estimated Fair Value	1,864	1,995
Gross Unrealized Losses	150	20
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	46,392	18,688
Gross Unrealized Losses - Less than 12 months	668	91
Estimated Fair Value - 12 months or greater	110,326	111,560
Gross Unrealized Losses - 12 months or greater	3,058	1,596
Estimated Fair Value	156,718	130,248
Gross Unrealized Losses	3,726	1,687
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	1,194	1,369
Gross Unrealized Losses - 12 months or greater	24	22
Estimated Fair Value	1,194	1,369
Gross Unrealized Losses	24	22
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	1,101,941	566,699
Gross Unrealized Losses - Less than 12 months	25,546	5,852
Estimated Fair Value - 12 months or greater	241,914	224,439
Gross Unrealized Losses - 12 months or greater	9,032	6,004
Estimated Fair Value	1,343,855	791,138
Gross Unrealized Losses	34,578	11,856
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	0
Gross Unrealized Losses - Less than 12 months	0	0
Estimated Fair Value - 12 months or greater	1,148	1,489
Gross Unrealized Losses - 12 months or greater	47	53
Estimated Fair Value	1,148	1,489
Gross Unrealized Losses	47	53
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	807,714	434,274
Gross Unrealized Losses - Less than 12 months	10,637	2,707
Estimated Fair Value - 12 months or greater	139,676	168,524
Gross Unrealized Losses - 12 months or greater	3,187	2,434
Estimated Fair Value	947,390	602,798
Gross Unrealized Losses	13,824	5,141
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	612,214	220,401
Gross Unrealized Losses - Less than 12 months	11,097	1,914
Estimated Fair Value - 12 months or greater	104,426	103,269
Gross Unrealized Losses - 12 months or greater	4,601	2,920
Estimated Fair Value	716,640	323,670
Gross Unrealized Losses	15,698	4,834
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	584,758	800,298
Gross Unrealized Losses - Less than 12 months	20,707	6,177
Estimated Fair Value - 12 months or greater	747,679	767,197
Gross Unrealized Losses - 12 months or greater	45,958	15,756
Estimated Fair Value	1,332,437	1,567,495
Gross Unrealized Losses	66,665	21,933
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	168,817	43,510
Gross Unrealized Losses - Less than 12 months	5,064	242
Estimated Fair Value - 12 months or greater	66,122	68,666
Gross Unrealized Losses - 12 months or greater	4,257	4,054
Estimated Fair Value	234,939	112,176
Gross Unrealized Losses	9,321	4,296
Debt Security, Government, Non-US [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	146,374	28,600
Gross Unrealized Losses - Less than 12 months	7,111	113
Estimated Fair Value - 12 months or greater	7,643	15,134
Gross Unrealized Losses - 12 months or greater	355	551
Estimated Fair Value	154,017	43,734
Gross Unrealized Losses	7,466	664
Debt Security, Government, Non-US [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	919,229	369,717
Gross Unrealized Losses - Less than 12 months	25,758	2,707
Estimated Fair Value - 12 months or greater	199,578	191,265
Gross Unrealized Losses - 12 months or greater	5,407	4,704
Estimated Fair Value	1,118,807	560,982
Gross Unrealized Losses	$ 31,165	7,411
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		82
Gross Unrealized Losses - Less than 12 months		1
Estimated Fair Value - 12 months or greater		26,471
Gross Unrealized Losses - 12 months or greater		2,225
Estimated Fair Value		26,553
Gross Unrealized Losses		2,226
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		5,820
Gross Unrealized Losses - Less than 12 months		1,023
Estimated Fair Value - 12 months or greater		47,251
Gross Unrealized Losses - 12 months or greater		398
Estimated Fair Value		53,071
Gross Unrealized Losses		$ 1,421

Investments (Investment Income

Investments (Investment Income Net of Related Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	$ 549,734	$ 537,583	$ 1,088,116	$ 1,070,617
Investment expense	(21,673)	(19,045)	(43,726)	(37,715)
Investment income, net of related expenses	528,061	518,538	1,044,390	1,032,902
Available-for-sale Securities [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	373,624	355,735	742,827	680,235
Equity securities
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	709	995	2,391	2,354
Mortgage Loans on Real Estate [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	50,460	44,442	100,659	88,789
Policy loans
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	14,775	15,194	29,555	30,466
Funds withheld at interest
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	86,417	97,367	161,862	224,945
Short-term Investments [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	2,964	1,779	6,209	3,289
Other invested assets
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	$ 20,785	$ 22,071	$ 44,613	$ 40,539

Investments (Investment Related

Investments (Investment Related Gains (Losses) Net) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investment Gains And Losses [Abstract]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 3,350	$ 3,401	$ 3,350	$ 20,590
Gain on investment activity	(21,140)	(54,197)	(32,106)	(72,090)
Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments	(35,934)	(10,288)	(56,314)	(18,975)
Available-for-sale Equity Securities, Gross Unrealized Gain	469	23	497	23
Available-for-sale Equity Securities, Gross Unrealized Loss	0	(183)	(950)	(4,059)
Gain (Loss) on Sale of Equity Investments	(6,966)	0	(11,103)	0
Other impairment losses and change in mortgage loan provision	(1,357)	(6,675)	(1,669)	(6,774)
Derivatives and other, net	15,426	22,622	29,741	95,103
Total investment related gains (losses), net	$ (10,572)	$ 56,295	$ (11,042)	$ 116,818

Investments (Borrowed Securitie

Investments (Borrowed Securities Repurchased Securities And Repurchased Reversed Repurchased Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Securities Loaned, Fair Value of Collateral	$ 102,208	$ 121,551
Securities Received as Collateral	112,000	128,000
Securities for Reverse Repurchase Agreements	385,391	413,819
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	397,712	417,550
Reported Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Securities Borrowed	350,350	358,875
Securities Loaned, Fair Value of Collateral	101,995	117,246
Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Securities Borrowed	365,730	377,820
Securities for Reverse Repurchase Agreements	$ 394,698	$ 428,344

Investments (Securities Pledged

Investments (Securities Pledged as Collateral Related to Repurchase Reverse Repurchase Program) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	$ 102,208	$ 121,551
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	394,698	428,344
Obligation to Return Securities Received as Collateral	496,906	549,895
Securities Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	539,332	576,786
SecuredBorrowingsGrossDifferenceAmount	42,426	26,891
Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	1,131
Obligation to Return Securities Received as Collateral	1,131	1,131
Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Obligation to Return Securities Received as Collateral	0	0
Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	312
Obligation to Return Securities Received as Collateral	0	312
Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	393,567	426,901
Obligation to Return Securities Received as Collateral	495,775	548,452
Corporate Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	102,208	121,551
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	151,519	184,646
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	0	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	0
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	312
Corporate Debt Securities [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	102,208	121,551
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	151,519	184,334
US Government Agencies Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement		220,765
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		220,765
US Treasury and Government [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	219,154
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	0
US Treasury and Government [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	219,154
Debt Security, Government, Non-US [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	22,894	21,802
Debt Security, Government, Non-US [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Debt Security, Government, Non-US [Member] | Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Debt Security, Government, Non-US [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	0
Debt Security, Government, Non-US [Member] | Maturity over 90 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	22,894	21,802
Other Debt Obligations [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	1,131	1,131
Other Debt Obligations [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	1,131	1,131
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	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 4,572,563		$ 4,413,171
Percentage of total	100.00%		100.00%
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ (4,188)		$ (3,254)
Allowance for Loan and Lease Losses, Real Estate	(9,706)	$ (8,864)	(9,384)	$ (8,156)	$ (7,786)	$ (7,685)
Mortgage loans on real estate (net of allowances of $9,706 and $9,384)	4,558,669		4,400,533
Apartment
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 530,599		$ 510,052
Percentage of total	11.60%		11.60%
Retail
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 1,296,157		$ 1,270,676
Percentage of total	28.30%		28.80%
Office building
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 1,546,148		$ 1,487,392
Percentage of total	33.90%		33.60%
Industrial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 962,049		$ 938,612
Percentage of total	21.00%		21.30%
Other commercial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 237,610		$ 206,439
Percentage of total	5.20%		4.70%

Investments (Mortgage Loans b52

Investments (Mortgage Loans by Maturity Date) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 4,572,563	$ 4,413,171
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
Due within five years
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 1,153,623	$ 1,091,066
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	25.20%	24.80%
Due after five years through ten years
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 2,623,105	$ 2,516,872
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	57.40%	57.00%
Due after ten years
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 795,835	$ 805,233
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	17.40%	18.20%

Investments (Mortgage Loans b53

Investments (Mortgage Loans by Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 4,572,563	$ 4,413,171
Loans Receivable, Gross, Commercial, Construction	$ 17,602	$ 9,686
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	$ 2,264,623	$ 2,206,208
Loans Receivable, Gross, Commercial, Construction	$ 17,602	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	49.50%	50.00%
LTV 60 To 69 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 1,719,540	$ 1,608,078
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	37.60%	36.40%
LTV 70 To 79 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 441,608	$ 431,274
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	9.70%	9.80%
LTV 80 to 100 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 146,792	$ 167,611
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 9,686
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	3.20%	3.80%
Debt Service Coverage Ratio Range One [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 4,095,040	$ 4,182,753
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	2,125,328	2,148,428
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	1,552,568	1,517,029
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	315,274	396,446
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	101,870	120,850
Debt Service Coverage Ratio Range Two [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	258,059	151,281
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	102,254	53,979
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	117,751	47,128
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	25,121	19,461
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	12,933	30,713
Debt Service Coverage Ratio Range Three [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	201,862	69,451
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	19,439	3,801
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	49,221	43,921
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	101,213	15,367
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	$ 31,989	$ 6,362

Investments (Age Analysis of Pa

Investments (Age Analysis of Past Due Recorded Investments) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 12,027	$ 19,156
Financing Receivable, Recorded Investment, Current	4,560,536	4,394,015
Loans Receivable, Gross, Commercial, Real Estate	4,572,563	4,413,171
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	12,027	17,100
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 0	$ 2,056

Investments (Mortgage Loans b55

Investments (Mortgage Loans by Method of Evaluation and Related Valuation Allowances) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Mortgage Loans:
Total mortgage loans	$ 4,572,563	$ 4,413,171
Mortgage Loans on Real Estate, Commercial and Consumer, Net, (Investment Based Operations Presentation) [Abstract]
Mortgage loans on real estate (net of valuation allowances)	4,558,669	4,400,533
Commercial Real Estate Portfolio Segment [Member]
Mortgage Loans:
Evaluated individually for credit losses	30,653	5,858
Evaluated collectively for credit losses	4,541,910	4,407,313
Total mortgage loans	4,572,563	4,413,171
Valuation Allowances:
Specific for credit losses	0	0
Non-specifically identified credit losses	9,706	9,384
Total valuation allowances	$ 9,706	$ 9,384

Investments (Loan Valuation All

Investments (Loan Valuation Allowance for Mortgage Loans) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Allowance For Loan And Lease Losses Roll Forward
Balance, Beginning of Period	$ 8,864	$ 7,786	$ 9,384	$ 7,685
Provision (release)	845	366	329	467
Allowance for Loan and Lease Losses, Foreign Currency Translation	(3)	4	(7)	4
Balance, End of Period	$ 9,706	$ 8,156	$ 9,706	$ 8,156

Investments (Impaired Mortgage

Investments (Impaired Mortgage Loans) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		$ 30,690		$ 30,690		$ 6,427
Recorded Investment		30,653		30,653		5,858
Related Allowance		0		0		0
Carrying Value		30,653		30,653		5,858
Average Investment	[1]	27,038	$ 2,088	19,978	$ 2,131
Interest Income		247	33	304	67
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	0
Interest Income		0	0	0	0
Impaired mortgage loans with no valuation allowance recorded
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		30,690		30,690		6,427
Recorded Investment		30,653		30,653		5,858
Related Allowance		0		0		0
Carrying Value		30,653		30,653		$ 5,858
Average Investment	[1]	27,038	2,088	19,978	2,131
Interest Income		$ 247	$ 33	$ 304	$ 67
[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	Jun. 30, 2018	Dec. 31, 2017
Other invested assets	$ 1,605,562	$ 1,505,332
Equity Release Mortgages [Member]
Other invested assets	311,723	219,940
Limited Partner [Member]
Other invested assets	857,599	781,124
Derivatives
Other invested assets	137,315	137,613
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Other invested assets	212,202	218,541
Other
Other invested assets	$ 86,723	$ 148,114

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)securities	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)securities	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)securities
Investment Narrative [Line Items]
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash	$ 29,600		$ 29,600		$ 31,200
Net Amount Assets Liabilities From Repurchase Reverse Repurchase Agreements	400		400		$ 1,100
Proceeds From Sale Of Available For Sale Securities Sold At Loss	1,174,400	$ 696,400	2,438,000	$ 1,125,000
Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments	$ 35,934	10,288	$ 56,314	18,975
Policy Loans Percent Of Total Investments	2.70%		2.70%		2.60%
Mortgage Loan Percent Of Cash And Invested Assets	9.00%		9.00%		8.50%
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities	2,580		2,580		1,116
Securities As Percentage Of Consolidated Stockholder Equity	10.00%		10.00%
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	11.80%		11.80%
Funds withheld at interest	$ 5,981,092		$ 5,981,092		$ 6,083,388
Funds Held Under Reinsurance Agreements Asset Specific Client	$ 4,000,000		$ 4,000,000
Other Invested Assets Percent Of Cash And Invested Assets	3.20%		3.20%		2.90%
ProceedsFromSaleOfAvailableForSaleEquitySecuritiesSoldAtLoss		14,100	$ 28,400	161,700
Available-for-sale Equity Securities, Gross Unrealized Loss	$ 0	$ 183	$ 950	$ 4,059
CALIFORNIA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	19.40%		19.40%
TEXAS
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	9.60%		9.60%
WASHINGTON
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	7.80%		7.80%
CANADA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	2.60%		2.60%

Derivative Instruments (Gross N

Derivative Instruments (Gross Notional Amount and Fair Value of Derivatives Contracts) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount	$ 16,661,842	$ 15,904,127
Carrying Value / Fair Value of Assets	342,747	320,724
Derivative Liability, Fair Value, Gross Liability	954,719	1,058,727
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	14,928,629	14,243,031
Carrying Value / Fair Value of Assets	265,821	254,252
Derivative Liability, Fair Value, Gross Liability	932,422	1,022,122
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	1,084,555	996,204
Carrying Value / Fair Value of Assets	43,439	59,809
Derivative Liability, Fair Value, Gross Liability	2,514	2,372
Not Designated as Hedging Instrument | Financial Futures
Derivative [Line Items]
Notional Amount	348,874	412,438
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	4,512	6,030
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	8	28
Not Designated as Hedging Instrument | Consumer Price Index Swap [Member]
Derivative [Line Items]
Notional Amount	328,190	221,932
Carrying Value / Fair Value of Assets	1,126	0
Derivative Liability, Fair Value, Gross Liability	199	2,160
Not Designated as Hedging Instrument | Credit Default Swaps
Derivative [Line Items]
Notional Amount	928,300	961,200
Carrying Value / Fair Value of Assets	6,725	8,319
Derivative Liability, Fair Value, Gross Liability	122	1,651
Not Designated as Hedging Instrument | Equity Options
Derivative [Line Items]
Notional Amount	639,801	632,251
Carrying Value / Fair Value of Assets	25,950	23,271
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument | Longevity Swap [Member]
Derivative [Line Items]
Notional Amount	934,720	960,400
Carrying Value / Fair Value of Assets	43,971	40,659
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument | Mortality Swap [Member]
Derivative [Line Items]
Notional Amount	25,000	0
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	782	1,683
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	144,610	122,194
Derivative Liability, Fair Value, Gross Liability	0	0
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	806,436	861,758
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	122,361	152,470
Not Designated as Hedging Instrument | Synthetic Guaranteed Investment Contracts
Derivative [Line Items]
Notional Amount	10,634,677	10,052,576
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	1,733,213	1,661,096
Carrying Value / Fair Value of Assets	76,926	66,472
Derivative Liability, Fair Value, Gross Liability	22,297	36,605
Designated As Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	435,000	435,000
Carrying Value / Fair Value of Assets	204	0
Derivative Liability, Fair Value, Gross Liability	19,699	20,389
Designated As Hedging Instrument | Foreign Currency Forwards
Derivative [Line Items]
Notional Amount	718,177	553,175
Carrying Value / Fair Value of Assets	18,428	1,265
Derivative Liability, Fair Value, Gross Liability	0	7,720
Designated As Hedging Instrument | Currency Swap [Member]
Derivative [Line Items]
Notional Amount	580,036	672,921
Carrying Value / Fair Value of Assets	58,294	65,207
Derivative Liability, Fair Value, Gross Liability	$ 2,598	$ 8,496

Derivative Instruments (Derivat

Derivative Instruments (Derivative Instruments Offsetting Balance Sheet) (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Derivative Assets [Abstract]
Derivative Fair Value Of Free Standing Derivative Asset		$ 198,137	$ 198,530
Gross Amounts Offset in the Balance Sheet		(16,851)	(20,258)
Net Amounts Presented in the Balance Sheet		181,286	178,272
Derivative Asset, Fair Value of Collateral	[1]	0	(862)
Gross Amounts Not Offset in the Balance Sheet - Cash Collateral Pledged/Received	[2]	(194,067)	(185,900)
Net Amount		(12,781)	(8,490)
Derivative Liabilities [Abstract]
Derivative Fair Value Of Free Standing Derivative Liability		25,922	44,499
Gross Amounts Offset in the Balance Sheet		(16,851)	(20,258)
Net Amounts Presented in the Balance Sheet		9,071	24,241
Gross Amounts Not Offset in the Balance Sheet - Financial Instruments	[3]	(57,302)	(58,156)
Gross Amounts Not Offset in the Balance Sheet - Cash Collateral Pledged/Received	[4]	(9,030)	(22,221)
Net Amount		$ (57,261)	$ (56,136)
[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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ (1,134)	$ 905	$ (3,025)	$ 7,441
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ 4,942	$ (905)	$ 6,833	$ (7,441)

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				6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2016	Mar. 31, 2015	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (22,656)	$ (1,131)	$ (20,662)	$ (7,690)	$ (22,656)	$ (1,131)	$ (2,619)	$ 2,496
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	2,099	(6,417)			19,916	4,016
Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(76)	(183)			(221)	(430)
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	41			0	41
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (29)	$ 0			$ 342	$ 0

Derivative Instruments (Cash Fl

Derivative Instruments (Cash Flow Hedges) (Details) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2016	Mar. 31, 2015	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	$ 2,099	$ (6,417)			$ 19,916	$ 4,016
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	22,656	1,131	$ 20,662	$ 7,690	22,656	1,131	$ 2,619	$ (2,496)
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	(41)			0	(41)
Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	76	183			221	430
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	29	0			(342)	0
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	4,742	(7,643)			19,727	(5,427)
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
Interest Rate Swap [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	29	0			(342)	0
Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	(2,643)	1,226			189	9,443
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	76	132			221	329
Currency Swap [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 0	0			$ 0	0
Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax		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		(41)				(41)
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		51				101
Forward Contracts [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		$ 0				$ 0

Derivative Instruments (Hedges

Derivative Instruments (Hedges of Net Investments in Foreign Operations) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	$ 19,260	$ (13,761)	$ 40,301	$ (21,367)
Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	8,197	(17,919)	17,002	(25,525)
Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	$ 11,063	$ 4,158	$ 23,299	$ 4,158
[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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	$ (10,572)	$ 56,295	$ (11,042)	$ 116,818
Policy acquisition costs and other insurance expenses	(320,276)	(319,832)	(677,178)	(699,221)
Interest credited	109,327	115,285	189,776	222,969
Other revenues	83,959	73,992	159,256	142,149
Gain Loss On Investments Related To Change In Fair Value Of Derivatives Excluding Embedded Derivatives	(14,151)	3,684	(33,625)	(19,164)
Not Designated as Hedging Instrument
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	16,497	13,197	50,770	65,012
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(8,600)	14,289	(35,171)	11,677
Not Designated as Hedging Instrument | Financial Futures
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(897)	(6,442)	(768)	(19,217)
Not Designated as Hedging Instrument | Foreign Currency Forwards
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(262)	(351)	61	553
Not Designated as Hedging Instrument | Consumer Price Index Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	1,041	(4)	3,227	(9)
Not Designated as Hedging Instrument | Credit Default Swaps
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	1,084	3,879	682	11,237
Not Designated as Hedging Instrument | Equity Options
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(8,007)	(9,273)	(5,414)	(26,462)
Not Designated as Hedging Instrument | Longevity Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Other revenues	2,289	1,981	4,557	3,847
Not Designated as Hedging Instrument | Mortality Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Other revenues	(799)	(395)	(799)	(790)
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	8,805	15,108	22,416	83,810
Not Designated as Hedging Instrument | Embedded Derivatives In Indexed Annuity [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Interest credited	6,519	5,955	31,870	22,357
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	$ 15,324	$ 360	$ 30,109	$ 22,723

Derivative Instruments (Exposur

Derivative Instruments (Exposure from Credit Derivatives by Rating of the Underlying Credits) (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 6,603	$ 7,572
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 928,300	$ 951,300
Derivative Average Remaining Maturity	[1],[3]	3 years	3 years 5 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]	$ 2,574	$ 3,128
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 152,000	$ 162,000
Derivative Average Remaining Maturity	[1],[3]	2 years 8 months	2 years 11 months
Standard Poors AAA To A Minus Ratings [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 2,574	$ 3,128
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 152,000	$ 162,000
Derivative Average Remaining Maturity	[1],[3]	2 years 8 months	2 years 11 months
Standard Poors BBB Rating [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 4,092	$ 4,469
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 338,700	$ 361,700
Derivative Average Remaining Maturity	[1],[3]	2 years 7 months	2 years 11 months
Standard Poors BBB Rating [Member] | Credit Default Swaps Referencing Indices [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (59)	$ (55)
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 422,600	$ 422,600
Derivative Average Remaining Maturity	[1],[3]	3 years 6 months	4 years
Standard Poors BBB Rating [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 4,033	$ 4,414
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 761,300	$ 784,300
Derivative Average Remaining Maturity	[1],[3]	3 years 1 month	3 years 6 months
Standard & Poor's, BB Rating [Member]
Credit Derivatives [Line Items]
Derivative Average Remaining Maturity	[1],[2]	1 year 2 months	1 year 6 months
Standard & Poor's, BB Rating [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (4)	$ 30
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	15,000	5,000
Standard & Poor's, BB Rating [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	(4)	30
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 15,000	$ 5,000
[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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
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	$ (14,151)	$ 3,684	$ (33,625)	$ (19,164)
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	8,805	15,108	22,416	83,810
Derivative, Gain (Loss) on Derivative, Net	5,987	2,941	12,836	28,785
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	6,519	(5,955)	31,870	(22,357)
Derivative, Gain (Loss) on Derivative, Net	3,966	(6,925)	10,503	(28,322)
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	15,324	360	30,109	22,723
Derivative, Gain (Loss) on Derivative, Net	$ 12,472	$ 3,023	$ 23,598	$ 31,859

Derivative Instruments (Credit

Derivative Instruments (Credit Exposure of Derivative Contracts) (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Credit Exposure of Derivative Contracts
Estimated fair value of derivatives in net asset (liability) position		$ 172,997	$ 155,714
Derivative, Collateral, Right to Reclaim Cash	[1]	9,030	22,221
Derivative Liability, Fair Value of Collateral	[2]	57,302	58,156
Derivative, Collateral, Obligation to Return Cash	[3]	(194,067)	(185,900)
Derivative Asset, Fair Value of Collateral	[4]	0	(862)
Deposits with Clearing Organizations and Others, Securities	[2]	(57,302)	(58,156)
Net credit exposure		(12,040)	(8,827)
Margin account related to exchange-traded futures	[5]	$ 8,331	$ 6,538
[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	Jun. 30, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative Foreign Currency Translation Gain Loss Recorded In Accumulated Other Comprehensive Income Loss For Terminated Net Investment In Foreign Operations Hedges	$ 154	$ 113.7
Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	0.4
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 1.5

Fair Value of Assets and Liab71

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	Jun. 30, 2018	Dec. 31, 2017
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 36,784,954	$ 38,150,820
Non Redeemable Preferred Stock Equity Method Investments Fair Value Disclosure		39,806
Equity Method Investments, Fair Value Disclosure	108,070	60,346
Funds withheld at interest embedded derivatives	144,610	122,194
Cash and cash equivalents	424,601	356,788
Short-term investments	82,521	50,746
Investments, Fair Value Disclosure	349,517	356,154
Other Assets, Fair Value Disclosure	43,971	40,659
Assets, Fair Value Disclosure	37,938,244	39,177,513
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	928,797	1,014,228
Liabilities Fair Value Disclosure
Financial Liabilities Fair Value Disclosure	937,868	1,038,469
Interest Rate Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	36,170	51,359
Liabilities Fair Value Disclosure
Other liabilities	(14,740)	(14,311)
Foreign Currency Forwards
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	18,428	730
Liabilities Fair Value Disclosure
Other liabilities	(8)	(7,213)
Consumer Price Index Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	(42)	(221)
Liabilities Fair Value Disclosure
Other liabilities	969	(1,939)
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	212,202	218,541
Credit Default Swaps
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	5,927	5,908
Liabilities Fair Value Disclosure
Other liabilities	(676)	(760)
Equity Option [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	21,136	16,932
Liabilities Fair Value Disclosure
Other liabilities	(4,814)	(6,339)
Currency Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	55,696	62,905
Liabilities Fair Value Disclosure
Other liabilities		(6,194)
Mortality Swap [Member]
Liabilities Fair Value Disclosure
Other liabilities	(782)	(1,683)
Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	22,503,507	23,210,968
Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	4,062,843	4,220,076
Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,821,214	1,719,880
Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,708,824	1,648,362
Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,242,509	1,303,387
US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,525,150	1,943,592
US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	737,044	703,428
Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,183,863	3,401,127
Fair Value Inputs Level 1 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,405,485	1,818,006
Non Redeemable Preferred Stock Equity Method Investments Fair Value Disclosure		39,806
Equity Method Investments, Fair Value Disclosure	65,133	60,346
Funds withheld at interest embedded derivatives	0	0
Cash and cash equivalents	409,242	354,071
Short-term investments	991	0
Investments, Fair Value Disclosure	211,141	217,618
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	2,091,992	2,489,847
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	0	0
Liabilities Fair Value Disclosure
Financial Liabilities Fair Value Disclosure	0	0
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	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	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	211,141	217,618
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
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	0	0
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	1,405,485	1,818,006
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 | Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	0
Fair Value Inputs Level 2 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	33,269,941	34,098,204
Non Redeemable Preferred Stock Equity Method Investments Fair Value Disclosure		0
Equity Method Investments, Fair Value Disclosure	0	0
Funds withheld at interest embedded derivatives	0	0
Cash and cash equivalents	15,359	2,717
Short-term investments	78,313	47,650
Investments, Fair Value Disclosure	138,376	138,536
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	33,501,989	34,287,107
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	0	0
Liabilities Fair Value Disclosure
Financial Liabilities Fair Value Disclosure	8,289	22,558
Fair Value Inputs Level 2 Member | Interest Rate Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	36,170	51,359
Liabilities Fair Value Disclosure
Other liabilities	(14,740)	(14,311)
Fair Value Inputs Level 2 Member | Foreign Currency Forwards
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	18,428	730
Liabilities Fair Value Disclosure
Other liabilities	(8)	(7,213)
Fair Value Inputs Level 2 Member | Consumer Price Index Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	(42)	(221)
Liabilities Fair Value Disclosure
Other liabilities	969	(1,939)
Fair Value Inputs Level 2 Member | Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	1,061	923
Fair Value Inputs Level 2 Member | Credit Default Swaps
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	5,927	5,908
Liabilities Fair Value Disclosure
Other liabilities	(676)	(760)
Fair Value Inputs Level 2 Member | Equity Option [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	21,136	16,932
Liabilities Fair Value Disclosure
Other liabilities	(4,814)	(6,339)
Fair Value Inputs Level 2 Member | Currency Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	55,696	62,905
Liabilities Fair Value Disclosure
Other liabilities		(6,194)
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	21,136,353	21,873,696
Fair Value Inputs Level 2 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,490,145	3,626,134
Fair Value Inputs Level 2 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,766,375	1,611,998
Fair Value Inputs Level 2 Member | Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,638,138	1,524,888
Fair Value Inputs Level 2 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,240,642	1,300,153
Fair Value Inputs Level 2 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	98,930	103,075
Fair Value Inputs Level 2 Member | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	720,539	662,225
Fair Value Inputs Level 2 Member | Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,178,819	3,396,035
Fair Value Inputs Level 3 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	2,109,528	2,234,610
Non Redeemable Preferred Stock Equity Method Investments Fair Value Disclosure		0
Equity Method Investments, Fair Value Disclosure	42,937	0
Funds withheld at interest embedded derivatives	144,610	122,194
Cash and cash equivalents	0	0
Short-term investments	3,217	3,096
Investments, Fair Value Disclosure	0	0
Other Assets, Fair Value Disclosure	43,971	40,659
Assets, Fair Value Disclosure	2,344,263	2,400,559
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	928,797	1,014,228
Liabilities Fair Value Disclosure
Financial Liabilities Fair Value Disclosure	929,579	1,015,911
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	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	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
Fair Value Inputs Level 3 Member | Mortality Swap [Member]
Liabilities Fair Value Disclosure
Other liabilities	(782)	(1,683)
Fair Value Inputs Level 3 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,367,154	1,337,272
Fair Value Inputs Level 3 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	572,698	593,942
Fair Value Inputs Level 3 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	54,839	107,882
Fair Value Inputs Level 3 Member | Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	70,686	123,474
Fair Value Inputs Level 3 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,867	3,234
Fair Value Inputs Level 3 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	20,735	22,511
Fair Value Inputs Level 3 Member | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	16,505	41,203
Fair Value Inputs Level 3 Member | Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 5,044	$ 5,092

Fair Value of Assets and Liab72

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Quantitative Information for Level 3 Inputs) (Details) $ in Thousands	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 37,938,244	$ 39,177,513
Corporate Debt Securities [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 571,750	$ 173,579
Corporate Debt Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0.01
Corporate Debt Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.02	0.02
Corporate Debt Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0	0
Longevity Swap [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 43,971	$ 40,659
US Government Agencies Debt Securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 20,735	$ 22,511
US Government Agencies Debt Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0
US Government Agencies Debt Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0
US Government Agencies Debt Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0	0
US States and Political Subdivisions Debt Securities [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 4,361	$ 4,616
US States and Political Subdivisions Debt Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0.01
US States and Political Subdivisions Debt Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0.01
US States and Political Subdivisions Debt Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0.01
Debt Security, Corporate, Non-US [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0
Debt Security, Corporate, Non-US [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0
Debt Security, Corporate, Non-US [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0
Foreign Government Debt [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 5,044	$ 0
Equity securities | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 23,856	$ 0
Equity securities | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	0.01	0
Equity securities | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	0.01	0
Equity securities | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	0.01	0
Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 144,610	$ 122,194
Embedded Derivatives In Indexed Annuity [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 806,436	$ 861,758
Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.02	0.02
Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.04	0.04
Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.02	0.02
Embedded Derivatives In Variable Annuity [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 122,361	$ 152,470
Mortality Swap [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 782	$ 1,683
Measurement Input, Mortality Rate [Member] | Longevity Swap [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.02	0.02
Measurement Input, Mortality Rate [Member] | Longevity Swap [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	1	1
Measurement Input, Mortality Rate [Member] | Longevity Swap [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0	0
Measurement Input, Mortality Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.02	0.02
Measurement Input, Mortality Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	1	1
Measurement Input, Mortality Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0	0
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.02	0.02
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	1	1
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0	0
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.01	0.01
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	1	1
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0	0
Measurement Input, Mortality Rate [Member] | Mortality Swap [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0.01
Measurement Input, Mortality Rate [Member] | Mortality Swap [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	1	1
Measurement Input, Mortality Rate [Member] | Mortality Swap [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0	0
Measurement Input, Lapse Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.09	0.09
Measurement Input, Lapse Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.35	0.35
Measurement Input, Lapse Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0	0
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.09	0.09
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.35	0.35
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0	0
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.05	0.05
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.25	0.25
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0	0
Measurement Input, Withdrawal Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.03	0.03
Measurement Input, Withdrawal Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.05	0.05
Measurement Input, Withdrawal Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0	0
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.03	0.03
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.05	0.05
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0	0
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.04	0.03
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.07	0.07
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0	0
Measurement Input, Counterparty Credit Risk [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.01	0.01
Measurement Input, Counterparty Credit Risk [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.05	0.05
Measurement Input, Counterparty Credit Risk [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0	0
Measurement Input, Counterparty Credit Risk [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.01	0.01
Measurement Input, Counterparty Credit Risk [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.05	0.05
Measurement Input, Counterparty Credit Risk [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0	0
Measurement Input, Long-term Revenue Growth Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.14	0.08
Measurement Input, Long-term Revenue Growth Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.27	0.27
Measurement Input, Long-term Revenue Growth Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0	0
Measurement Input Crediting Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.02	0.02
Measurement Input Crediting Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.04	0.04
Measurement Input Crediting Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset, Measurement Input	0.02	0.02
Measurement Input, EBITDA Multiple [Member] | Corporate Debt Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	6.9	0
Measurement Input, EBITDA Multiple [Member] | Corporate Debt Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	7.5	0
Measurement Input, EBITDA Multiple [Member] | Corporate Debt Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	5.9	0
Measurement Input, EBITDA Multiple [Member] | Equity securities | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	7.9	0
Measurement Input, EBITDA Multiple [Member] | Equity securities | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	13.1	0
Measurement Input, EBITDA Multiple [Member] | Equity securities | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	6.9	0
Measurement Input Mortality Improvement [Member] | Longevity Swap [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.03	0.03
Measurement Input Mortality Improvement [Member] | Longevity Swap [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.10	0.10
Measurement Input Mortality Improvement [Member] | Longevity Swap [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	(0.10)	(0.10)

Fair Value of Assets and Liab73

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] $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2017USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$ 0	$ 0
Fair Value, Assets, Level 2 to Level 1 Transfers, Description	49,999	88,674

Fair Value of Assets and Liab74

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		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Corporate Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		$ 1,299,264	$ 1,263,925	$ 1,337,272	$ 1,272,253
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		2,178	(4,548)	(30,674)	400
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	155,498	104,087	255,668	150,001
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(11,089)	(23,174)	17,269	23,174
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(68,328)	(74,531)	143,474	146,001
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0	17,264	7,166	31,198
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(6,923)	0	37,728	0
Fair Value, end of period		1,367,154	1,291,054	1,367,154	1,291,054
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		(305)	(396)	(666)	(819)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(304)	(396)	(665)	(819)
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		(3,141)	8,427	(3,141)	7,196
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(3,141)	(1,495)	(3,141)	(2,788)
Canadian Provincial Governments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		572,747	483,560	593,942	475,965
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(3,517)	46,509	(28,156)	51,034
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		572,698	533,270	572,698	533,270
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		3,468	3,201	6,912	6,271
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		3,468	3,201	6,912	6,271
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	0	0	0
Residential mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		120,614	143,430	107,882	160,291
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(671)	1,962	(1,781)	2,612
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	24,412	29,318	45,328	45,817
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(4,961)	(4,467)	4,961	15,071
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(1,572)	(4,655)	4,535	11,439
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		3,031	5,423	3,031	5,500
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(86,283)	(22,412)	90,302	39,231
Fair Value, end of period		54,839	148,685	54,839	148,685
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		(43)	(29)	(135)	(274)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(13)	(37)	(105)	(128)
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		312	115	312	480
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0	0	0	(346)
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		130,706	208,436	123,474	219,280
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(1,544)	1,136	(691)	6,903
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0	34,366	11,000	45,215
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]	(19,544)	(27,569)	22,283	45,723
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		4,968	3,500	4,968	38,758
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(45,258)	(18,791)	47,248	64,373
Fair Value, end of period		70,686	201,589	70,686	201,589
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		76	511	182	1,529
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		68	239	174	400
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		1,282	0	1,284	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0	0	0	0
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		41,876	33,858	41,203	41,666
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(110)	823	590	(20)
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
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(86)	241	121	274
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(25,165)		25,165	6,844
Fair Value, end of period		16,505	34,434	16,505	34,434
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		(10)	(6)	(2)	(94)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(11)	(6)	(3)	(94)
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
Debt Security, Government, Non-US [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		5,004		5,092
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		40		(48)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0
Fair Value, end of period		5,044		5,044
Debt Security, Government, Non-US [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
Foreign Government Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period			12,344		12,869
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)			(12)		(203)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]		338		672
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3					0
Fair Value, end of period			11,994		11,994
Foreign Government Debt [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
Foreign Government Debt [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
US Government Agencies Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		21,053	23,474	22,511	24,488
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(173)	211	(513)	263
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	118	132	214	236
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(156)	135	1,260	1,188
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0	0
Fair Value, end of period		20,735	23,567	20,735	23,567
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		(107)	(115)	(217)	(232)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(108)	(115)	(218)	(232)
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
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		1,884	1,923	3,234	21,145
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(16)	21	(63)	(62)
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]				3,720
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(2)	1	3	5,402
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		1		1,301	10,132
Fair Value, end of period		1,867	1,943	1,867	1,943
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	0	0	709
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0	0	0	0
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					(595)
ERROR in label resolution.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		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		135,805	46,173	122,194	(22,529)
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	[1]	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
Fair Value, end of period		144,610	61,281	144,610	61,281
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
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		8,805	15,108	22,416	83,810
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		8,805	15,108	22,416	83,810
Funds Withheld At Interest Embedded Derivatives [Member] | Insurance Claims [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
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] | Policy Acquisition Costs And Other Insurance Expenses [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
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		44,011	29,170	40,659	26,958
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(2,329)	2,198	(1,245)	2,545
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
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
Fair Value, end of period		43,971	33,349	43,971	33,349
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
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] | Insurance Claims [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
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] | Policy Acquisition Costs And Other Insurance Expenses [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
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		2,289	1,981	4,557	3,846
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		2,289	1,981	4,557	3,846
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	[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		(964,794)	(972,930)	(1,014,228)	(990,308)
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]	(4,205)	(19,533)	(12,713)	(25,927)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	18,359	23,427	36,165	41,238
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0
Fair Value, end of period		(928,797)	(974,631)	(928,797)	(974,631)
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
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		(15,324)	(360)	(30,109)	(22,723)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(13,474)	1,794	(26,375)	(18,505)
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Insurance Claims [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
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		6,519	(5,955)	31,870	(22,357)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		11,839	29,382	4,295	63,596
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Policy Acquisition Costs And Other Insurance Expenses [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
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		1,683	2,857	1,683	2,462
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]	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	1,700	1,700	1,700	1,700
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0
Fair Value, end of period		(782)	(1,552)	(782)	(1,552)
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
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] | Insurance Claims [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
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] | Policy Acquisition Costs And Other Insurance Expenses [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
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		799	395	799	790
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		799	395	(799)	790
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		36,152		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	12,248		12,248
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(541)		569
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		48
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		38,905
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0
Fair Value, end of period		42,937		42,937
Equity 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		0
Equity 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		(4,922)		(7,599)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(5,000)		(7,705)
Equity securities | Insurance Claims [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
Equity 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		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0
Equity securities | Policy Acquisition Costs And Other Insurance Expenses [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
Equity securities | 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
ERROR in label resolution.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		3,217	3,276	3,096	3,346
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(21)	(29)	(46)	4
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	335	324	481	356
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(314)	(23)	314	(158)
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
Fair Value, end of period		3,217	3,548	3,217	3,548
ERROR in label resolution. | 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
ERROR in label resolution. | 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
ERROR in label resolution. | Insurance Claims [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
ERROR in label resolution. | 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
ERROR in label resolution. | Policy Acquisition Costs And Other Insurance Expenses [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
ERROR in label resolution. | 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
[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 Liab75

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Fair Value Assets Measured on Non-Recurring Basis) (Details) - Partnership Interest [Member] - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
		Jun. 30, 2017	Jun. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets Carrying Value Prior To Impairment	[1]		$ 3,690
Fair Value Assets Gains Losses	[1]	$ (6,308)	$ (6,308)
[1]	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.

Fair Value of Assets and Liab76

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		Jun. 30, 2018		Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Assets
Mortgage loans on real estate (net of valuation allowances)		$ 4,558,669		$ 4,400,533
Policy loans		1,339,252		1,357,624
Funds withheld at interest		5,981,092		6,083,388
Cash and cash equivalents		1,397,679		1,303,524	$ 1,123,350	$ 1,200,718
Short-term investments		123,028		93,304
Other invested assets		1,605,562		1,505,332
Accrued investment income		400,160		392,721
Liabilities
Interest-sensitive contract liabilities		16,513,668		16,227,642
Long-term debt		2,788,111		2,788,365
Collateral finance and securitization notes		724,998		783,938
Reported Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)	[1]	4,558,669		4,400,533
Policy loans	[1]	1,339,252		1,357,624
Funds withheld at interest	[1]	5,836,373		5,955,092
Cash and cash equivalents	[1]	973,078		946,736
Short-term investments	[1]	40,507		42,558
Other invested assets	[1]	757,264		651,792
Accrued investment income	[1]	400,160		392,721
Liabilities
Interest-sensitive contract liabilities	[1]	13,072,239		12,683,872
Long-term debt	[1]	2,788,111
Debt, Long-term and Short-term, Combined Amount	[1]			2,788,365
Collateral finance and securitization notes	[1]	724,998		783,938
Estimate of Fair Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)		4,461,317		4,477,654
Policy loans		1,339,252		1,357,624
Funds withheld at interest		6,057,217		6,275,623
Cash and cash equivalents		973,078		946,736
Short-term investments		40,507		42,558
Other invested assets		775,322		679,377
Accrued investment income		400,160		392,721
Liabilities
Interest-sensitive contract liabilities		12,972,203	[1]	12,917,243
Long-term Debt, Fair Value		2,868,837
Debt, Long-term and Short-term, Combined Amount				2,959,912
Collateral finance and securitization notes		666,356		722,145
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		0		0
Cash and cash equivalents		973,078		946,736
Short-term investments		40,507		42,558
Other invested assets		5,565		28,540
Accrued investment income		0		0
Liabilities
Interest-sensitive contract liabilities		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		1,339,252		1,357,624
Funds withheld at interest		0		0
Cash and cash equivalents		0		0
Short-term investments		0		0
Other invested assets		71,797		67,778
Accrued investment income		400,160		392,721
Liabilities
Interest-sensitive contract liabilities		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)		4,461,317		4,477,654
Policy loans		0		0
Funds withheld at interest		6,057,217		6,275,623
Cash and cash equivalents		0		0
Short-term investments		0		0
Other invested assets		323,142		247,934
Accrued investment income		0		0
Liabilities
Interest-sensitive contract liabilities		12,972,203		12,917,243
Long-term Debt, Fair Value		2,868,837
Debt, Long-term and Short-term, Combined Amount				2,959,912
Collateral finance and securitization notes		666,356		722,145
Estimate of Fair Value Measurement [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)		0		0
Policy loans		0		0
Funds withheld at interest		0		0
Cash and cash equivalents		0		0
Short-term investments		0		0
Other invested assets		374,818		335,125
Accrued investment income		0		0
Liabilities
Interest-sensitive contract liabilities		0		0
Long-term Debt, Fair Value		0
Debt, Long-term and Short-term, Combined Amount				0
Collateral finance and securitization notes		$ 0		$ 0
[1]	aid.June 30, 2018: Carrying Value (1) Estimated Fair Value Fair Value Measurement Using:Level 1 Level 2 Level 3 NAVAssets: Mortgage loans on real estate $4,558,669 $4,461,317 $— $— $4,461,317 $—Policy loans 1,339,252 1,339,252 — 1,339,252 — —Funds withheld at interest 5,836,373 6,057,217 — — 6,057,217 —Cash and cash equivalents 973,078 973,078 973,078 — — —Short-term investments 40,507 40,507 40,507 — — —Other invested assets 757,264 775,322 5,565 71,797 323,142 374,818Accrued investment income 400,160 400,160 — 400,160 — —Liabilities: Interest-sensitive contract liabilities $13,072,239 $12,972,203 $— $— $12,972,203 $—Long-term debt 2,788,111 2,868,837 — — 2,868,837 —Collateral finance and securitization notes 724,998 666,356 — — 666,356 — December 31, 2017: Carrying Value (1) Estimated Fair Value Fair Value Measurement Using:Level 1 Level 2 Level 3 NAVAssets: Mortgage loans on real estate $4,400,533 $4,477,654 $— $— $4,477,654 $—Policy loans 1,357,624 1,357,624 — 1,357,624 — —Funds withheld at interest 5,955,092 6,275,623 — — 6,275,623 —Cash and cash equivalents 946,736 946,736 946,736 — — —Short-term investments 42,558 42,558 42,558 — — —Other invested assets 651,792 679,377 28,540 67,778 247,934 335,125Accrued investment income 392,721 392,721 — 392,721 — —Liabilities: Interest-sensitive contract liabilities $12,683,872 $12,917,243 $— $— $12,917,243 $—Long-term debt 2,788,365 2,959,912 — — 2,959,912 —Collateral finance and securitization notes 783,938 722,145 — — 722,145 — (1)Carrying values presented herein may differ from those in the Company’s condensed consolidated balance sheets because certain items within the respective financial statement captions may be measured at fair value on a recurring basis.

Fair Value of Assets and Liab77

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Equity securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	$ 0	$ 38,905

Segment Information (Total Reve

Segment Information (Total Revenues of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 3,195,908	$ 3,129,276	$ 6,369,615	$ 6,138,016
Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,794,095	1,794,674	3,497,141	3,582,023
CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	324,288	281,276	639,384	557,358
EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	473,213	419,325	955,138	817,400
Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	588,512	579,513	1,222,897	1,105,195
Corporate and Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	15,800	54,488	55,055	76,040
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,564,147	1,522,698	3,053,841	3,011,201
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	312,199	269,273	614,518	533,548
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	372,538	345,920	766,320	664,006
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	570,520	561,529	1,185,059	1,066,759
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	229,948	271,976	443,300	570,822
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	12,089	12,003	24,866	23,810
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	100,675	73,405	188,818	153,394
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 17,992	$ 17,984	$ 37,838	$ 38,436

Segment Information (Income Los

Segment Information (Income Loss Before Provision for Income Tax of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
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	$ 247,288	$ 339,315	$ 385,213	$ 547,159
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	154,366	197,579	224,679	331,125
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	25,349	37,261	52,247	60,181
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	71,837	40,259	126,422	86,153
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	63,000	58,699	89,908	106,259
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	(67,264)	5,517	(108,043)	(36,559)
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	71,978	90,594	74,870	120,554
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	21,805	32,836	45,512	52,164
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	6,468	11,354	21,889	25,330
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	58,862	53,322	81,749	95,010
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	82,388	106,985	149,809	210,571
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	3,544	4,425	6,735	8,017
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	65,369	28,905	104,533	60,823
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	$ 4,138	$ 5,377	$ 8,159	$ 11,249

Segment Information (Total Asse

Segment Information (Total Assets of Reportable Segments) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 59,766,497	$ 60,514,818
Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	35,081,538	34,562,629
CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,344,925	4,287,824
EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	8,164,458	8,374,488
Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,315,917	6,114,027
Corporate and Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,859,659	7,175,850
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,038,145	18,603,423
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,203,344	4,161,452
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,335,264	3,099,495
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,159,546	4,915,442
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	16,043,393	15,959,206
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	141,581	126,372
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,829,194	5,274,993
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 1,156,371	$ 1,198,585

Commitments, Contingencies an81

Commitments, Contingencies and Guarantees (Commitments to Fund Investments) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Limited Partner [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 490,601	$ 485,197
Commercial Loan [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	113,992	40,815
Bank Loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	98,652	60,472
Equity Release Mortgages [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 157,069	$ 153,937

Commitments, Contingencies an82

Commitments, Contingencies and Guarantees (Maximum Potential Obligation) (Details) $ in Millions	Jun. 30, 2018USD ($)
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	1,932
Commitment Period Two Thousand Thirty Seven [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	6,750
Commitment Period Two Thousand Thirty Eight [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 800

Commitments, Contingencies an83

Commitments, Contingencies and Guarantees (Guarantees Issued) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Insurance Treaty Guarantee [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 913,902	$ 1,047,449
Insurance Treaty Guarantee Net Of Assets Held In Trust [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	802,073	926,393
Guarantee Of Borrowed Securities [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	289,210	294,325
Product Financing Arrangement [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	74,864	86,183
Guarantee Of Lease Obligations [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 1,137	$ 1,662

Income Tax (Provision for Incom

Income Tax (Provision for Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 51,931	$ 118,760	$ 80,895	$ 191,506
Tax Adjustments, Settlements, and Unusual Provisions	(4,314)	0	(3,539)	0
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	(330)	(4,261)	1,103	(10,413)
Income Tax Reconciliation Foreign Income Tax Basis Differential	(1,132)	(13,375)	(6,892)	(16,759)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	3,079	13,031	10,501	14,213
Effective Income Tax Rate Reconciliation, Tax Contingency, Domestic, Amount	(2,036)	(1,783)	(1,201)	(1,172)
Income Tax Reconciliation Change In Foreign Enacted Tax Rate	145	44	417	(1,193)
Income Tax Reconciliation SubpartF	(348)	1,140	310	1,326
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount	113	(1,938)	(459)	(2,064)
Effective Income Tax Rate Reconciliation Global Intangible Low Taxed Income	(119)	0	4,291	0
Effective Income Tax Rate Reconciliation, Equity in Earnings (Losses) of Unconsolidated Subsidiary, Amount	3,135	2,609	4,250	4,464	$ 10,500
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount	(503)	(633)	(139)	(403)
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	(437)	(1,251)	(428)	(1,120)
Income Tax Expense (Benefit)	$ 42,914	$ 107,125	$ 80,609	$ 169,457
Effective Income Tax Rate Reconciliation, Percent	17.40%	31.60%	20.90%	31.00%

Employee Benefit Plans (Defined

Employee Benefit Plans (Defined Benefit Plans Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,570	$ 2,819	$ 6,224	$ 5,399
Interest cost	1,357	1,431	2,687	2,629
Expected return on plan assets	(2,213)	(1,823)	(3,767)	(3,108)
Amortization of prior service cost	82	95	165	169
Amortization of prior actuarial loss	769	1,082	1,863	2,163
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	256	0	513
Total	3,565	3,860	7,172	7,765
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	636	721	1,272	1,442
Interest cost	529	565	1,059	1,130
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(329)	(155)	(658)	(311)
Amortization of prior actuarial loss	498	457	996	914
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0	0
Total	$ 1,334	$ 1,588	$ 2,669	$ 3,175

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
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	$ 8

Reinsurance (Ceded Reinsurance

Reinsurance (Ceded Reinsurance Receivable Assets) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 789,429	$ 782,027
Reinsurance Recoverables, Percentage of Total	100.00%	100.00%
Other Reinsurers [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 129,801	$ 127,808
Reinsurance Recoverables, Percentage of Total	16.40%	16.20%
AM Best, A+ Rating [Member] | Reinsurer A [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 312,405	$ 301,478
Reinsurance Recoverables, Percentage of Total	39.60%	38.60%
AM Best, A+ Rating [Member] | Reinsurer B [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 198,782	$ 203,898
Reinsurance Recoverables, Percentage of Total	25.20%	26.10%
AM Best, A+ Rating [Member] | Reinsurer D [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 41,807	$ 40,528
Reinsurance Recoverables, Percentage of Total	5.30%	5.20%
AM Best, A Rating [Member] | Reinsurer C [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 67,699	$ 67,723
Reinsurance Recoverables, Percentage of Total	8.60%	8.70%
AM Best, A++ Rating [Member] | Reinsurer E [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 38,935	$ 40,592
Reinsurance Recoverables, Percentage of Total	4.90%	5.20%

Reinsurance (Narrative) (Detail

Reinsurance (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Ceded Credit Risk [Line Items]
Reinsurance Claims Recoverables	$ 271.2	$ 243.8
Claims Recoverable From Retrocessionaires Past Due	$ 3.1	$ 1.9
AM Best, A- Rating [Member]
Ceded Credit Risk [Line Items]
Ceded Credit Risk, Disclosure	“A- (excellent)”	“A- (excellent)”
AM Best, B++ Rating [Member]
Ceded Credit Risk [Line Items]
Ceded Credit Risk, Disclosure	B++

New Accounting Standards New Ac

New Accounting Standards New Accounting Standards (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					$ 156,400
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	$ 3,135	$ 2,609	$ 4,250	$ 4,464	10,500
Contractual Obligation					$ 38,200