Reinsurance Group of America (RGA) 10-Q 2 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document And Entitiy Information [Abstract]
Document Type	10-Q
Document period end date	Sep. 30, 2018
Amendment flag	false
Entity registrant name	REINSURANCE GROUP OF AMERICA INC
Entity central index key	898,174
Entity current reporting status	Yes
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Common Shares Outstanding		62,774,675
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Emerging Growth Company	false
Entity Small Business	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Fixed maturity securities available-for-sale, at fair value (amortized cost $37,751,132 and $35,281,412)	$ 39,005,212	$ 38,150,820
Equity Securities, FV-NI	101,069	100,152
Mortgage loans on real estate (net of allowances of $10,366 and $9,384)	4,779,074	4,400,533
Policy loans	1,320,050	1,357,624
Funds withheld at interest	5,976,301	6,083,388
Short-term investments	229,928	93,304
Other invested assets	1,706,979	1,505,332
Total investments	53,118,613	51,691,153
Cash and cash equivalents	1,730,489	1,303,524
Accrued investment income	455,296	392,721
Premiums receivable and other reinsurance balances	2,779,556	2,338,481
Reinsurance ceded receivables	769,324	782,027
Deferred policy acquisition costs	3,211,145	3,239,824
Other assets	908,219	767,088
Total assets	62,972,642	60,514,818
Liabilities and Stockholders’ Equity
Future policy benefits	25,139,148	22,363,241
Interest-sensitive contract liabilities	16,751,379	16,227,642
Other policy claims and benefits	5,424,347	4,992,074
Other reinsurance balances	482,235	488,739
Deferred income taxes	1,883,848	2,198,309
Other liabilities	1,213,595	1,102,975
Long-term debt	2,787,975	2,788,365
Collateral finance and securitization notes	710,792	783,938
Total liabilities	54,393,319	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 September 30, 2018 and December 31, 2017	791	791
Additional paid-in capital	1,899,144	1,870,906
Retained earnings	7,215,526	6,736,265
Treasury stock, at cost - 16,186,890 and 14,685,663 shares	(1,348,943)	(1,102,058)
Accumulated other comprehensive income	812,805	2,063,631
Total stockholders’ equity	8,579,323	9,569,535
Total liabilities and stockholders’ equity	$ 62,972,642	$ 60,514,818

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS PARENTHETICAL - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Available for Sale at Fair value - Amortized cost	$ 37,751,132	$ 35,281,412
Available-for-sale Equity Securities, Amortized Cost Basis	$ 111,248	$ 102,841
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	77,450,868	64,452,095
Treasury stock, shares	1,686,890	14,685,663
Allowances for Loan and Lease Losses, Real Estate	$ 10,366	$ 9,384

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Net premiums	$ 2,562,042	$ 2,489,797	$ 7,739,053	$ 7,335,944
Investment income, net of related expenses	572,742	556,918	1,617,132	1,589,820
Investment related gains (losses), net:
Other-than-temporary impairments on fixed maturity securities	(10,705)	(390)	(14,055)	(20,980)
Other investment related gains (losses), net	(9,312)	23,043	(17,004)	160,451
Total investment related gains (losses), net	(20,017)	22,653	(31,059)	139,471
Other revenues	112,764	75,942	272,020	218,091
Total revenues	3,227,531	3,145,310	9,597,146	9,283,326
Benefits and Expenses:
Claims and other policy benefits	2,209,920	2,100,680	6,851,614	6,371,188
Interest credited	143,292	126,099	333,068	349,068
Policy acquisition costs and other insurance expenses	310,639	365,424	987,817	1,064,645
Other operating expenses	200,262	168,417	586,495	481,279
Interest expense	33,290	36,836	107,769	108,590
Collateral finance and securitization expense	7,467	7,692	22,509	21,235
Total benefits and expenses	2,904,870	2,805,148	8,889,272	8,396,005
Income before income taxes	322,661	340,162	707,874	887,321
Provision for income taxes	21,462	112,571	102,071	282,028
Net income	$ 301,199	$ 227,591	$ 605,803	$ 605,293
Earnings per share:
Basic earnings per share	$ 4.76	$ 3.53	$ 9.47	$ 9.39
Diluted earnings per share	4.68	3.47	9.30	9.23
Dividends declared per share	$ 0.60	$ 0.50	$ 1.60	$ 1.32

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Comprehensive income (loss)
Net income	$ 301,199	$ 227,591	$ 605,803	$ 605,293
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	25,462	46,733	(30,375)	68,085
Net unrealized investment gains (losses)	(215,986)	(93,574)	(1,218,309)	415,870
Defined benefit pension and postretirement plan adjustments	931	700	431	2,473
Total other comprehensive income (loss), net of tax	(189,593)	(46,141)	(1,248,253)	486,428
Total comprehensive income (loss)	$ 111,606	$ 181,450	$ (642,450)	$ 1,091,721

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 605,803	$ 605,293
Change in operating assets and liabilities:
Accrued investment income	23,473	(63,321)
Premiums receivable and other reinsurance balances	(519,107)	(421,027)
Deferred policy acquisition costs	23,682	67,471
Reinsurance ceded receivable balances	37,468	(120,013)
Future policy benefits, other policy claims and benefits, and other reinsurance balances	920,492	982,164
Deferred income taxes	(8,136)	236,185
Other assets and other liabilities, net	(47,978)	78,848
Amortization of net investment premiums, discounts and other	(55,154)	(95,227)
Depreciation, Depletion and Amortization	32,153	21,384
Investment related (gains) losses, net	31,059	(139,471)
Other, net	56,408	(47,787)
Net cash provided by operating activities	1,100,163	1,104,499
Cash Flows from Investing Activities:
Sales of fixed maturity securities available-for-sale	6,314,968	6,364,236
Maturities of fixed maturity securities available-for-sale	461,764	385,993
Proceeds from Sale of Available-for-sale Securities, Equity	44,952	192,821
Payments to Acquire Debt Securities, Available-for-sale	6,041,665	7,450,749
Payments to Acquire Available-for-sale Securities, Equity	(12,578)	(60,790)
Payments to Acquire Mortgage Notes Receivable	(671,956)	(751,702)
Proceeds from Sale and Collection of Mortgage Notes Receivable	290,450	208,052
Proceeds from Collection of Policy Loans	43,995	93,286
Payments for (Proceeds from) Policy Loans	6,422	5,830
Increase (Decrease) in Funds Held under Reinsurance Agreements	61,969	12,597
Payments to Acquire Businesses, Net of Cash Acquired	31,441	0
Payments to Acquire Property, Plant, and Equipment	(20,478)	(33,242)
Change in short-term investments	34,856	65,664
Change in other invested assets	(313,464)	(51,476)
Net cash provided by (used in) investing activities	31,012	(1,056,334)
Cash Flows from Financing Activities:
Dividends to stockholders	(102,441)	(85,086)
Proceeds from (Repayments of) Secured Debt	(75,146)	(56,637)
Repayments of Long-term Debt	(2,007)	(301,927)
Purchases of treasury stock	(273,873)	(41,360)
Exercise of stock options, net	2,336	4,450
Change in cash collateral for derivative positions and other arrangements	(21,288)	(46,206)
Deposits on universal life and other investment type policies and contracts	320,871	1,007,563
Withdrawals on universal life and other investment type policies and contracts	(520,649)	(568,789)
Net cash used in financing activities	(672,197)	(87,992)
Effect of exchange rate changes on cash	(32,013)	43,699
Change in cash and cash equivalents	426,965	3,872
Cash and cash equivalents, beginning of period	1,303,524	1,200,718
Cash and cash equivalents, end of period	1,730,489	1,204,590
Supplemental disclosures of cash flow information:
Interest Paid, Excluding Capitalized Interest, Operating Activities	124,575	129,136
Income Taxes Paid, Net	99,554	27,385
Transfer to Investments	3,763,195	2,247,136
Noncash or Part Noncash Acquisition, Value of Assets Acquired	69,853	0
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	$ (38,412)	$ 0

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (PARENTHETICAL) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Statement of Cash Flows [Abstract]
Cash Acquired from Acquisition	$ 4,938

Business and Basis of Presentat

Business and Basis of Presentation	9 Months Ended
	Sep. 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 nine months ended September 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	9 Months Ended
	Sep. 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 September 30, Nine months ended September 30, 2018 2017 2018 2017 Earnings: Net income (numerator for basic and diluted calculations) $ 301,199 $ 227,591 $ 605,803 $ 605,293 Shares: Weighted average outstanding shares (denominator for basic calculation) 63,279 64,488 63,941 64,430 Equivalent shares from outstanding stock options 1,017 1,165 1,189 1,174 Denominator for diluted calculation 64,296 65,653 65,130 65,604 Earnings per share: Basic $ 4.76 $ 3.53 $ 9.47 $ 9.39 Diluted $ 4.68 $ 3.47 $ 9.30 $ 9.23 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 thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Excluded from common equivalent shares: Stock options 227 87 349 296 Performance contingent shares 276 307 256 293

Equity

Equity	9 Months Ended
	Sep. 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 — 1,750,295 (1,750,295 ) Stock-based compensation (1) — (249,068 ) 249,068 Balance, September 30, 2018 79,137,758 16,186,890 62,950,868 Issued Held In Treasury Outstanding Balance, December 31, 2016 79,137,758 14,835,256 64,302,502 Common stock acquired — 208,680 (208,680 ) Stock-based compensation (1) — (274,449 ) 274,449 Balance, September 30, 2017 79,137,758 14,769,487 64,368,271 (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 nine months of 2018, RGA repurchased 1.8 million shares of common stock under this program for $258.5 million . During the first nine months of 2017, RGA repurchased 0.2 million shares of common stock under this program for $26.9 million . Accumulated Other Comprehensive Income (Loss) The balance of and changes in each component of accumulated other comprehensive income (loss) (“AOCI”) for the nine months ended September 30, 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 (24,977 ) (1,638,146 ) (3,391 ) (1,666,514 ) Amounts reclassified to (from) AOCI — 79,505 3,986 83,491 Deferred income tax benefit (expense) (5,398 ) 340,332 (164 ) 334,770 Adoption of new accounting standard (2,573 ) — — (2,573 ) Balance, September 30, 2018 $ (119,298 ) $ 982,352 $ (50,249 ) $ 812,805 Accumulated Currency Translation Adjustments Unrealized Appreciation (Depreciation) of Investments (1) Pension and Postretirement Benefits Total Balance, December 31, 2016 $ (172,541 ) $ 1,355,033 $ (43,163 ) $ 1,139,329 Other comprehensive income (loss) before reclassifications 23,117 671,564 (191 ) 694,490 Amounts reclassified to (from) AOCI — (51,407 ) 4,006 (47,401 ) Deferred income tax benefit (expense) 44,968 (204,287 ) (1,342 ) (160,661 ) Balance, September 30, 2017 $ (104,456 ) $ 1,770,903 $ (40,690 ) $ 1,625,757 (1) Includes cash flow hedges of $29,043 and $2,619 as of September 30, 2018 and December 31, 2017 , respectively, and $347 and $(2,496) as of September 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 nine months ended September 30, 2018 and 2017 (dollars in thousands): Amount Reclassified from AOCI Three months ended September 30, Nine months ended September 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 $ (21,249 ) $ 10,515 $ (60,347 ) $ 39,032 Investment related gains (losses), net Cash flow hedges - Interest rate 234 — (108 ) — (1) Cash flow hedges - Currency/Interest rate 50 230 270 560 (1) Cash flow hedges - Forward bond purchase commitments — 224 — 286 (1) Deferred policy acquisition costs attributed to unrealized gains and losses (4,893 ) 1,116 (19,320 ) 11,529 (2) Total (25,858 ) 12,085 (79,505 ) 51,407 Provision for income taxes 5,355 (3,991 ) 16,978 (16,015 ) Net unrealized gains (losses), net of tax $ (20,503 ) $ 8,094 $ (62,527 ) $ 35,392 Amortization of defined benefit plan items: Prior service cost (credit) $ 246 $ 590 $ 739 $ 732 (3) Actuarial gains/(losses) (1,866 ) (1,661 ) (4,725 ) (4,738 ) (3) Total (1,620 ) (1,071 ) (3,986 ) (4,006 ) Provision for income taxes 340 375 837 1,402 Amortization of defined benefit plans, net of tax $ (1,280 ) $ (696 ) $ (3,149 ) $ (2,604 ) Total reclassifications for the period $ (21,783 ) $ 7,398 $ (65,676 ) $ 32,788 (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	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Based Compensation	Equity Based Compensation Equity compensation expense was $28.4 million and $17.1 million in the first nine 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 September 30, 2018 , 1.5 million share options at a weighted average strike price per share of $66.48 were vested and exercisable, with a remaining weighted average exercise period of 4.3 years. As of September 30, 2018 , the total compensation cost of non-vested awards not yet recognized in the condensed consolidated financial statements was $35.1 million . It is estimated that these costs will vest over a weighted average period of 1.3 years.

Investments

Investments	9 Months Ended
	Sep. 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 September 30, 2018 (dollars in thousands): September 30, 2018: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate $ 24,271,467 $ 594,444 $ 416,413 $ 24,449,498 62.7 % $ — Canadian government 2,902,433 1,138,426 4,109 4,036,750 10.3 — RMBS 1,816,949 14,235 50,422 1,780,762 4.6 — ABS 1,867,650 10,312 14,945 1,863,017 4.8 275 CMBS 1,282,015 8,403 16,884 1,273,534 3.3 — U.S. government 1,500,703 6,359 94,653 1,412,409 3.6 — State and political subdivisions 889,218 36,410 13,637 911,991 2.3 — Other foreign government 3,220,697 98,574 42,020 3,277,251 8.4 — Total fixed maturity securities $ 37,751,132 $ 1,907,163 $ 653,083 $ 39,005,212 100.0 % $ 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 September 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities pledged as collateral $ 67,899 $ 69,792 $ 72,542 $ 75,622 Fixed maturity securities received as collateral n/a 592,146 n/a 590,417 Assets in trust held to satisfy collateral requirements 19,263,724 19,670,559 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 September 30, 2018 and December 31, 2017 (dollars in thousands). September 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 $ 1,158,326 $ 1,833,972 $ 1,119,337 $ 1,917,996 Canadian province of Ontario 951,186 1,225,712 939,837 1,282,944 The amortized cost and estimated fair value of fixed maturity securities classified as available-for-sale at September 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 $ 986,289 $ 993,352 Due after one year through five years 7,797,732 7,888,116 Due after five years through ten years 9,311,737 9,407,186 Due after ten years 14,688,760 15,799,245 Asset and mortgage-backed securities 4,966,614 4,917,313 Total $ 37,751,132 $ 39,005,212 Corporate Fixed Maturity Securities The tables below show the major industry types of the Company’s corporate fixed maturity holdings as of September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018: Estimated Amortized Cost Fair Value % of Total Finance $ 8,561,885 $ 8,564,254 35.1 % Industrial 12,632,502 12,753,024 52.1 Utility 3,077,080 3,132,220 12.8 Total $ 24,271,467 $ 24,449,498 100.0 % 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 September 30, Nine months ended September 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 2,866 fixed maturity securities as of September 30, 2018 , where the estimated fair value had declined and remained below amortized cost by the indicated amount (dollars in thousands): September 30, 2018 Gross Unrealized Losses % of Total Less than 20% $ 640,481 98.1 % 20% or more for less than six months 309 — 20% or more for six months or greater 12,293 1.9 Total $ 653,083 100.0 % 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 an 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 2,866 fixed maturity securities that have estimated fair values below amortized cost as of September 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 September 30, 2018: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate $ 10,117,970 $ 303,926 $ 1,290,804 $ 81,236 $ 11,408,774 $ 385,162 Canadian government 58,816 1,211 107,167 2,736 165,983 3,947 RMBS 931,044 23,339 528,739 27,063 1,459,783 50,402 ABS 680,900 8,650 262,544 6,243 943,444 14,893 CMBS 555,716 8,304 207,943 8,580 763,659 16,884 U.S. government 197,114 3,913 1,002,661 90,740 1,199,775 94,653 State and political subdivisions 261,456 6,722 90,649 6,915 352,105 13,637 Other foreign government 1,034,417 24,666 297,566 11,062 1,331,983 35,728 Total investment grade securities 13,837,433 380,731 3,788,073 234,575 17,625,506 615,306 Below investment grade securities: Corporate 539,521 23,955 77,675 7,296 617,196 31,251 Canadian government 2,328 162 — — 2,328 162 RMBS — — 1,102 20 1,102 20 ABS — — 1,110 52 1,110 52 Other foreign government 140,692 5,931 6,410 361 147,102 6,292 Total below investment grade securities 682,541 30,048 86,297 7,729 768,838 37,777 Total fixed maturity securities $ 14,519,974 $ 410,779 $ 3,874,370 $ 242,304 $ 18,394,344 $ 653,083 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. 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 September 30, Nine months ended September 30, 2018 2017 2018 2017 Fixed maturity securities available-for-sale $ 378,669 $ 359,157 $ 1,121,496 $ 1,039,392 Equity securities 1,319 942 3,710 3,296 Mortgage loans on real estate 54,424 50,040 155,083 138,829 Policy loans 14,730 15,404 44,285 45,870 Funds withheld at interest 108,232 102,144 270,094 327,089 Short-term investments and cash and cash equivalents 3,067 1,977 9,276 5,266 Other invested assets 35,594 46,653 80,207 87,192 Investment income 596,035 576,317 1,684,151 1,646,934 Investment expense (23,293 ) (19,399 ) (67,019 ) (57,114 ) Investment income, net of related expenses $ 572,742 $ 556,918 $ 1,617,132 $ 1,589,820 Investment Related Gains (Losses), Net Investment related gains (losses), net consist of the following (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Fixed maturity securities available for sale: Other-than-temporary impairment losses $ (10,705 ) $ (390 ) $ (14,055 ) $ (20,980 ) Gain on investment activity 20,040 19,512 52,146 91,611 Loss on investment activity (37,880 ) (7,593 ) (94,194 ) (26,577 ) Equity securities: Other-than-temporary impairment losses — (889 ) — (889 ) Gain on investment activity 3,932 10 4,429 24 Loss on investment activity (174 ) (85 ) (1,124 ) (4,135 ) Change in unrealized gains (losses) recognized in earnings 3,539 — (7,564 ) — Other impairment losses and change in mortgage loan provision (6,566 ) (2,446 ) (8,235 ) (9,220 ) Derivatives and other, net 7,797 14,534 37,538 109,637 Total investment related gains (losses), net $ (20,017 ) $ 22,653 $ (31,059 ) $ 139,471 The fixed maturity impairments for the three and nine months ended September 30, 2018 and 2017 were largely related to high-yield corporate securities. The equity impairments for the three and nine months ended September 30, 2017 were related to an equity position received as part of a debt restructuring. The other impairment losses and change in mortgage loan provision for the three and nine months ended September 30, 2018 includes impairments on real estate joint ventures and limited partnerships. The other impairment losses and change in mortgage loan provision for the three and nine months ended September 30, 2017 includes impairments on limited partnerships. The fluctuations in investment related gains (losses) for derivatives and other for the three and nine months ended September 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 September 30, 2018 and 2017 , the Company sold fixed maturity securities with fair values of $1,345.3 million and $479.7 million at losses of $37.9 million and $7.6 million , respectively. During the nine months ended September 30, 2018 and 2017 , the Company sold fixed maturity securities with fair values of $3,783.3 million and $1,604.7 million at losses of $94.2 million and $26.6 million , respectively. During the three months ended September 30, 2018 and 2017 , the Company sold equity securities with fair values of $3.1 million and $5.0 million at losses of $0.2 million and $0.1 million , respectively. During the nine months ended September 30, 2018 and 2017 , the Company sold equity securities with fair values of $31.5 million and $166.7 million at losses of $1.1 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 September 30, 2018 and December 31, 2017 (dollars in thousands). September 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Borrowed securities $ 353,650 $ 370,323 $ 358,875 $ 377,820 Securities lending: Securities loaned 101,965 102,489 117,246 121,551 Securities received n/a 112,000 n/a 128,000 Repurchase program/reverse repurchase program: Securities pledged 408,679 404,905 413,819 428,344 Securities received n/a 400,515 n/a 417,550 The Company also held cash collateral for securities lending and the repurchase program/reverse repurchase programs of $28.9 million and $31.2 million at September 30, 2018 and December 31, 2017 , respectively. No cash or securities have been pledged by the Company for its securities borrowing program as of September 30, 2018 and December 31, 2017 . The following tables present information on the Company’s securities lending and repurchase transactions as of September 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. September 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 $ — $ — $ — $ 102,489 $ 102,489 Total — — — 102,489 102,489 Repurchase transactions: Corporate — — — 132,228 132,228 U.S. government — — — 219,906 219,906 Foreign government — — — 52,771 52,771 Other — — — — — Total — — — 404,905 404,905 Total transactions $ — $ — $ — $ 507,394 $ 507,394 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 541,411 Amounts related to agreements not included in offsetting disclosure $ 34,017 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 September 30, 2018 and December 31, 2017 , respectively. As of September 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 September 30, 2018 and December 31, 2017 . As of September 30, 2018 , mortgage loans were geographically dispersed throughout the U.S. with the largest concentrations in California ( 18.8% ), Texas ( 10.0% ) and Georgia ( 7.5% ) 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 Property type: Carrying Value % of Total Carrying Value % of Total Office building $ 1,633,887 34.1 % $ 1,487,392 33.6 % Retail 1,365,157 28.5 1,270,676 28.8 Industrial 983,553 20.5 938,612 21.3 Apartment 543,917 11.3 510,052 11.6 Other commercial 267,712 5.6 206,439 4.7 Recorded investment 4,794,226 100.0 % 4,413,171 100.0 % Unamortized balance of loan origination fees and expenses (4,786 ) (3,254 ) Valuation allowances (10,366 ) (9,384 ) Total mortgage loans on real estate $ 4,779,074 $ 4,400,533 The maturities of mortgage loans as of September 30, 2018 and December 31, 2017 are as follows (dollars in thousands): September 30, 2018 December 31, 2017 Recorded Investment % of Total Recorded Investment % of Total Due within five years $ 1,216,241 25.4 % $ 1,091,066 24.8 % Due after five years through ten years 2,738,400 57.1 2,516,872 57.0 Due after ten years 839,585 17.5 805,233 18.2 Total $ 4,794,226 100.0 % $ 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 September 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 September 30, 2018: Loan-to-Value Ratio 0% - 59.99% $ 2,146,401 $ 63,794 $ 43,486 $ 25,724 $ 2,279,405 47.6 % 60% - 69.99% 1,666,525 117,726 62,617 — 1,846,868 38.5 70% - 79.99% 386,137 70,884 76,054 — 533,075 11.1 Greater than 80% 108,233 22,429 4,216 — 134,878 2.8 Total $ 4,307,296 $ 274,833 $ 186,373 $ 25,724 $ 4,794,226 100.0 % 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 31-60 days past due $ — $ 17,100 61-90 days past due — 2,056 Total past due — 19,156 Current 4,794,226 4,394,015 Total $ 4,794,226 $ 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 Mortgage loans: Individually measured for impairment $ 30,629 $ 5,858 Collectively measured for impairment 4,763,597 4,407,313 Recorded investment $ 4,794,226 $ 4,413,171 Valuation allowances: Individually measured for impairment $ — $ — Collectively measured for impairment 10,366 9,384 Total valuation allowances $ 10,366 $ 9,384 Information regarding the Company’s loan valuation allowances for mortgage loans for the three and nine months ended September 30, 2018 and 2017 is as follows (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Balance, beginning of period $ 9,706 $ 8,156 $ 9,384 $ 7,685 Provision (release) 656 977 986 1,444 Translation adjustment 4 4 (4 ) 8 Balance, end of period $ 10,366 $ 9,137 $ 10,366 $ 9,137 Information regarding the portion of the Company’s mortgage loans that were impaired as of September 30, 2018 and December 31, 2017 is as follows (dollars in thousands): Unpaid Principal Balance Recorded Investment Related Allowance Carrying Value September 30, 2018: Impaired mortgage loans with no valuation allowance recorded $ 30,660 $ 30,629 $ — $ 30,629 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 30,660 $ 30,629 $ — $ 30,629 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 September 30, 2018 2017 Average (1) Interest Income Average Recorded Investment (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 30,641 $ 346 $ 3,967 $ 33 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 30,641 $ 346 $ 3,967 $ 33 Nine months ended September 30, 2018 2017 Average (1) Interest Income Average (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 22,641 $ 650 $ 3,062 $ 100 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 22,641 $ 650 $ 3,062 $ 100 (1) Average recorded investment represents the average loan balances as of the beginning of period and all subsequent quarterly end of period balances. The Company did not acquire any impaired mortgage loans during the nine months ended September 30, 2018 and 2017 . The Company had no mortgage loans that were on a nonaccrual status at September 30, 2018 and December 31, 2017 . Policy Loans Policy loans comprised approximately 2.5% and 2.6% of the Company’s total investments as of September 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 11.3% and 11.8% of the Company’s total investments as of both September 30, 2018 and December 31, 2017 . Of the $6.0 billion funds withheld at interest balance, net of embedded derivatives, as of September 30, 2018 , $3.9 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 September 30, 2018 and December 31, 2017 , respectively. Carrying values of these assets as of September 30, 2018 and December 31, 2017 are as follows (dollars in thousands): September 30, 2018 December 31, 2017 Limited partnership interests and real estate joint ventures $ 924,006 $ 781,124 Equity release mortgages 383,450 219,940 Derivatives 101,124 137,613 FVO contractholder-directed unit-linked investments 212,315 218,541 Other 86,084 148,114 Total other invested assets $ 1,706,979 $ 1,505,332

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 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 $ 1,074,173 $ 37,238 $ 1,818 $ 996,204 $ 59,809 $ 2,372 Financial futures 347,916 — — 412,438 — — Foreign currency forwards — — — 6,030 — 28 Consumer price index swaps 409,023 127 2,836 221,932 — 2,160 Credit default swaps 1,373,300 6,759 114 961,200 8,319 1,651 Equity options 571,845 19,372 — 632,251 23,271 — Longevity swaps 928,320 46,090 — 960,400 40,659 — Mortality swaps 25,000 — 308 — — 1,683 Synthetic guaranteed investment contracts 10,844,558 — — 10,052,576 — — Embedded derivatives in: Modified coinsurance or funds withheld arrangements — 142,529 — — 122,194 — Indexed annuity products — — 815,970 — — 861,758 Variable annuity products — — 90,229 — — 152,470 Total non-hedging derivatives 15,574,135 252,115 911,275 14,243,031 254,252 1,022,122 Derivatives designated as hedging instruments: Interest rate swaps 435,000 99 20,579 435,000 — 20,389 Foreign currency swaps 537,249 46,141 3,770 672,921 65,207 8,496 Foreign currency forwards 834,238 8,948 2,067 553,175 1,265 7,720 Total hedging derivatives 1,806,487 55,188 26,416 1,661,096 66,472 36,605 Total derivatives $ 17,380,622 $ 307,303 $ 937,691 $ 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 September 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 September 30, 2018: Derivative assets $ 164,774 $ (17,560 ) $ 147,214 $ — $ (159,194 ) $ (11,980 ) Derivative liabilities 31,492 (17,560 ) 13,932 (61,293 ) (13,400 ) (60,761 ) 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 September 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 September 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 September 30, 2018: Foreign currency swaps Foreign-denominated fixed maturity securities $ (2,258 ) $ 2,832 For the three months ended September 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 2,100 $ (2,100 ) For the nine months ended September 30, 2018: Foreign currency swaps Foreign-denominated fixed maturity securities $ (5,284 ) $ 9,666 For the nine months ended September 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 9,541 $ (9,541 ) (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 nine months ended September 30, 2018 and 2017 (dollars in thousands): Three months ended September 30, 2018 2017 Balance beginning of period $ 22,656 $ 7,690 Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges 6,671 (6,889 ) Amounts reclassified to investment related (gains) losses, net — (183 ) Amounts reclassified to investment income (50 ) (271 ) Amounts reclassified to interest expense (234 ) — Balance end of period $ 29,043 $ 347 Nine months ended September 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 26,586 3,689 Amounts reclassified to investment related (gains) losses, net — (142 ) Amounts reclassified to investment income (270 ) (704 ) Amounts reclassified to interest expense 108 — Balance end of period $ 29,043 $ 347 As of September 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 $0.2 million and $1.9 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 nine months ended September 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 September 30, 2018: Interest rate $ 7,490 $ — $ — $ 234 Currency/Interest rate (819 ) — 50 — Total $ 6,671 $ — $ 50 $ 234 For the three months ended September 30, 2017: Interest rate $ (8,421 ) $ — $ — $ — Currency/Interest rate 1,544 — 230 — Forward bond purchase commitments (12 ) 183 41 — Total $ (6,889 ) $ 183 $ 271 $ — For the nine months ended September 30, 2018: Interest rate $ 27,217 $ — $ — $ (108 ) Currency/Interest rate (631 ) — 270 — Total $ 26,586 $ — $ 270 $ (108 ) For the nine months ended September 30, 2017: Interest rate $ (6,205 ) $ — $ — $ — Currency/Interest rate 9,894 — 560 — Forward bond purchase commitments — 142 144 — Total $ 3,689 $ 142 $ 704 $ — For the three and nine months ended September 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 nine months ended September 30, 2018 and 2017 (dollars in thousands): Derivative Gains (Losses) Deferred in AOCI For the three months ended September 30, For the nine months ended September 30, Type of NIFO Hedge (1) (2) 2018 2017 2018 2017 Foreign currency swaps $ (5,877 ) $ (35,198 ) $ 11,125 $ (60,723 ) Foreign currency forwards (11,562 ) 4,627 11,737 8,785 Total $ (17,439 ) $ (30,571 ) $ 22,862 $ (51,938 ) (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 $136.5 million and $113.7 million at September 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 nine months ended September 30, 2018 and 2017 is as follows (dollars in thousands): Gain (Loss) for the three months ended September 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2018 2017 Interest rate swaps Investment related gains (losses), net $ (12,228 ) $ 641 Financial futures Investment related gains (losses), net (6,544 ) (8,890 ) Foreign currency forwards Investment related gains (losses), net (58 ) 24 CPI swaps Investment related gains (losses), net (4,223 ) 220 Credit default swaps Investment related gains (losses), net 4,689 4,137 Equity options Investment related gains (losses), net (9,793 ) (8,295 ) Longevity swaps Other revenues 2,426 3,334 Mortality swaps Other revenues 473 (132 ) Subtotal (25,258 ) (8,961 ) Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net (2,081 ) 23,044 Indexed annuity products Interest credited (25,347 ) (13,133 ) Variable annuity products Investment related gains (losses), net 32,133 (6,205 ) Total non-hedging derivatives $ (20,553 ) $ (5,255 ) Gain (Loss) for the nine months ended September 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2018 2017 Interest rate swaps Investment related gains (losses), net $ (47,399 ) $ 12,318 Financial futures Investment related gains (losses), net (7,312 ) (28,107 ) Foreign currency forwards Investment related gains (losses), net 3 577 CPI swaps Investment related gains (losses), net (996 ) 211 Credit default swaps Investment related gains (losses), net 5,371 15,374 Equity options Investment related gains (losses), net (15,207 ) (34,757 ) Longevity swaps Other revenues 6,983 7,180 Mortality swaps Other revenues (326 ) (921 ) Subtotal (58,883 ) (28,125 ) Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 20,335 106,854 Indexed annuity products Interest credited 6,523 (35,490 ) Variable annuity products Investment related gains (losses), net 62,242 16,518 Total non-hedging derivatives $ 30,217 $ 59,757 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 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 $ 2,470 $ 152,000 2.5 $ 3,128 $ 162,000 2.9 Subtotal 2,470 152,000 2.5 3,128 162,000 2.9 BBB+/BBB/BBB- Single name credit default swaps 4,220 343,700 2.4 4,469 361,700 2.9 Credit default swaps referencing indices (80 ) 642,600 3.4 (55 ) 422,600 4.0 Subtotal 4,140 986,300 3.1 4,414 784,300 3.5 BB+/BB/BB- Single name credit default swaps 32 15,000 1.0 30 5,000 1.5 Subtotal 32 15,000 1.0 30 5,000 1.5 Total $ 6,642 $ 1,153,300 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 nine months ended September 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 nine months ended September 30, 2018 and 2017 are reflected in the following table (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Embedded derivatives in modco or funds withheld arrangements included in investment related gains $ (2,081 ) $ 23,044 $ 20,335 $ 106,854 After the associated amortization of DAC and taxes, the related amounts included in net income (1,320 ) 7,515 11,517 36,300 Embedded derivatives in variable annuity contracts included in investment related gains 32,133 (6,205 ) 62,242 16,518 After the associated amortization of DAC and taxes, the related amounts included in net income 9,463 (1,074 ) 33,061 30,785 Amounts related to embedded derivatives in equity-indexed annuities included in benefits and expenses (25,347 ) (13,133 ) 6,523 (35,490 ) After the associated amortization of DAC and taxes, the related amounts included in net income (17,311 ) (9,737 ) (6,808 ) (38,059 ) 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 September 30, 2018 and December 31, 2017 are reflected in the following table (dollars in thousands): September 30, 2018 December 31, 2017 Estimated fair value of derivatives in net asset position $ 133,590 $ 155,714 Cash provided as collateral (1) 13,400 22,221 Securities pledged to counterparties as collateral (2) 61,293 58,156 Cash pledged from counterparties as collateral (3) (159,194 ) (185,900 ) Securities pledged from counterparties as collateral (4) — (862 ) Initial margin for cleared derivatives (2) (61,293 ) (58,156 ) Net amount after application of master netting agreements and collateral $ (12,204 ) $ (8,827 ) Margin account related to exchange-traded futures (5) $ 8,348 $ 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	9 Months Ended
	Sep. 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 September 30, 2018 and December 31, 2017 are summarized below (dollars in thousands): September 30, 2018: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate $ 24,449,498 $ — $ 23,193,563 $ 1,255,935 Canadian government 4,036,750 — 3,488,008 548,742 RMBS 1,780,762 — 1,780,762 — ABS 1,863,017 — 1,780,250 82,767 CMBS 1,273,534 — 1,271,752 1,782 U.S. government 1,412,409 1,284,932 107,225 20,252 State and political subdivisions 911,991 — 898,346 13,645 Other foreign government 3,277,251 — 3,272,239 5,012 Total fixed maturity securities – available-for-sale 39,005,212 1,284,932 35,792,145 1,928,135 Equity securities 101,069 57,584 — 43,485 Funds withheld at interest – embedded derivatives 142,529 — — 142,529 Cash equivalents 657,280 657,280 — — Short-term investments 186,051 5,957 177,891 2,203 Other invested assets: Derivatives: Interest rate swaps 29,106 — 29,106 — Foreign currency forwards 6,881 — 6,881 — CPI swaps (13 ) — (13 ) — Credit default swaps 5,961 — 5,961 — Equity options 16,818 — 16,818 — Foreign currency swaps 42,371 — 42,371 — FVO contractholder-directed unit-linked investments 212,315 211,253 1,062 — Total other invested assets 313,439 211,253 102,186 — Other assets - longevity swaps 46,090 — — 46,090 Total $ 40,451,670 $ 2,217,006 $ 36,072,222 $ 2,162,442 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 906,199 $ — $ — $ 906,199 Other liabilities: Derivatives: Interest rate swaps 14,166 — 14,166 — CPI swaps 2,696 — 2,696 — Credit default swaps (684 ) — (684 ) — Equity options (2,554 ) — (2,554 ) — Mortality swaps 308 — — 308 Total $ 920,131 $ — $ 13,624 $ 906,507 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 nine months ended September 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 nine months ended September 30, 2017 (dollars in thousands): 2017 Transfers from Level 1 to Level 2 Transfers from Level 2 to Level 1 Three months ended September 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ — Nine months ended September 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ 88,674 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 September 30, 2018 and December 31, 2017 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) September 30, 2018 December 31, 2017 September 30, 2018 December 31, 2017 Assets: Corporate $ 630,328 $ 173,579 Market comparable securities Liquidity premium 0-5% (1%) 0-2% (1%) EBITDA Multiple 5.9x-7.5x (6.9x) — ABS 64,475 — Market comparable securities Liquidity premium 0-1% (1%) — U.S. government 20,252 22,511 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions — 4,616 Market comparable securities Liquidity premium — 1 % Other foreign government 5,012 — Market comparable securities Liquidity premium 1 % — Equity securities 33,074 — Market comparable securities Liquidity premium 4 % — EBITDA Multiple 6.9x-12.3x (7.9x) — Discounted cash flow Discount rate 20 % Funds withheld at interest- embedded derivatives 142,529 122,194 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 46,090 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 815,970 861,758 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 90,229 152,470 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% (13%) 0-27% (8%) Mortality swaps 308 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. 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 September 30, 2018: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,367,154 $ 572,698 $ 54,839 $ 70,686 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (156 ) 3,520 3 20 Investment related gains (losses), net 239 — — 626 Included in other comprehensive income (4,858 ) (27,476 ) (1 ) (130 ) Purchases (1) 123,808 — — 11,099 Sales (1) (62,047 ) — — (462 ) Settlements (1) (101,868 ) — (3 ) (24,166 ) Transfers into Level 3 2,782 — — 64,009 Transfers out of Level 3 (69,119 ) — (54,838 ) (38,915 ) Fair value, end of period $ 1,255,935 $ 548,742 $ — $ 82,767 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 $ (180 ) $ 3,520 $ — $ 13 Investment related gains (losses), net (1,430 ) — — — For the three months ended September 30, 2018 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 1,867 $ 20,735 $ 16,505 $ 5,044 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (107 ) 6 — Included in other comprehensive income 7 (122 ) (544 ) (32 ) Purchases (1) — 120 — — Settlements (1) (1 ) (374 ) (37 ) — Transfers into Level 3 1,752 — 9,859 — Transfers out of Level 3 (1,843 ) — (12,144 ) — Fair value, end of period $ 1,782 $ 20,252 $ 13,645 $ 5,012 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 $ — $ (107 ) $ 6 $ — For the three months ended September 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 $ 42,937 $ 144,610 $ 3,217 $ 43,971 $ (928,797 ) $ (782 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net 5,532 (2,081 ) — — 32,133 — Interest credited — — — — (25,348 ) — Included in other comprehensive income — — 47 (307 ) — 1 Other revenues — — — 2,426 — 473 Purchases (1) 863 — 1,721 — (4,231 ) — Sales (1) (5,847 ) — — — — — Settlements (1) — — — — 20,044 — Transfers out of Level 3 — — (2,782 ) — — — Fair value, end of period $ 43,485 $ 142,529 $ 2,203 $ 46,090 $ (906,199 ) $ (308 ) 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 $ 2,178 $ (2,081 ) $ — $ — $ 30,433 $ — Other revenues — — — 2,426 — 473 Interest credited — — — — (45,393 ) — For the nine months ended September 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 (822 ) 10,432 (132 ) 202 Investment related gains (losses), net (2,902 ) — 312 1,910 Included in other comprehensive income (35,532 ) (55,632 ) (1,782 ) (821 ) Purchases (1) 379,476 — 45,328 22,099 Sales (1) (79,316 ) — (4,961 ) (462 ) Settlements (1) (245,342 ) — (4,538 ) (46,449 ) Transfers into Level 3 9,948 — 3,031 68,977 Transfers out of Level 3 (106,847 ) — (145,140 ) (86,163 ) Fair value, end of period $ 1,255,935 $ 548,742 $ — $ 82,767 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 $ (845 ) $ 10,432 $ — $ 187 Investment related gains (losses), net (4,571 ) — — — For the nine months ended September 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 — (324 ) 4 — Included in other comprehensive income (56 ) (635 ) 46 (80 ) Purchases (1) — 334 — — Settlements (1) (4 ) (1,634 ) (158 ) — Transfers into Level 3 1,752 — 9,859 — Transfers out of Level 3 (3,144 ) — (37,309 ) — Fair value, end of period $ 1,782 $ 20,252 $ 13,645 $ 5,012 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 $ — $ (325 ) $ 3 $ — For the nine months ended September 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 (2,067 ) 20,335 — — 62,242 — Interest credited — — — — 6,523 — Included in other comprehensive income — — 1 (1,552 ) — 1 Other revenues — — — 6,983 — (326 ) Purchases (1) 13,111 — 2,202 — (16,946 ) — Sales (1) (6,416 ) — — — — — Settlements (1) (48 ) — (314 ) — 56,210 1,700 Transfers into Level 3 38,905 — — — — — Transfers out of Level 3 — — (2,782 ) — — — Fair value, end of period $ 43,485 $ 142,529 $ 2,203 $ 46,090 $ (906,199 ) $ (308 ) 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 $ (5,527 ) $ 20,335 $ — $ — $ 56,808 $ — Other revenues — — — 6,983 — (326 ) Interest credited — — — — (49,688 ) — For the three months ended September 30, 2017: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,291,054 $ 533,270 $ 148,685 $ 201,589 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (383 ) 3,460 (30 ) 160 Investment related gains (losses), net 396 — 44 — Included in other comprehensive income (2,700 ) (11,365 ) 104 (101 ) Purchases (1) 107,670 — 26,765 — Sales (1) (26,337 ) — (3,553 ) — Settlements (1) (88,551 ) — (3,645 ) (15,243 ) Transfers into Level 3 3,844 — 15 36,994 Transfers out of Level 3 (12,973 ) — (50,390 ) (78,202 ) Fair value, end of period $ 1,272,020 $ 525,365 $ 117,995 $ 145,197 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (394 ) $ 3,460 $ (27 ) $ 156 For the three months ended September 30, 2017 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 1,943 $ 23,567 $ 34,434 $ 11,994 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (116 ) 26 (1 ) Included in other comprehensive income 5 6 (208 ) (7 ) Purchases (1) — 134 — 495 Settlements (1) (1 ) (340 ) (35 ) — Transfers into Level 3 — — 7,295 — Transfers out of Level 3 — — — (6,853 ) Fair value, end of period $ 1,947 $ 23,251 $ 41,512 $ 5,628 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ — $ (116 ) $ 26 $ (1 ) For the three months ended September 30, 2017 (continued): Short-term Investments Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 3,548 $ 61,281 $ 33,349 $ (974,631 ) $ (1,552 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 23,044 — (10,047 ) — Interest credited — — — (8,335 ) — Included in other comprehensive income (3 ) — 1,144 — 1 Other revenues — — 3,334 — (132 ) Purchases (1) 3,164 — — (18,736 ) — Settlements (1) (114 ) — — 21,809 — Transfers out of Level 3 (3,236 ) — — — — Fair value, end of period $ 3,359 $ 84,325 $ 37,827 $ (989,940 ) $ (1,683 ) Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment related gains (losses), net $ — $ 23,044 $ — $ (11,900 ) $ — Other revenues — — 3,334 — (132 ) Interest credited — — — (30,145 ) — For the nine months ended September 30, 2017: Fixed maturity securities - available-for-sale Corporate 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 (1,202 ) 9,731 (304 ) 1,689 Investment related gains (losses), net 7,592 — 524 — Included in other comprehensive income (2,300 ) 39,669 2,716 6,802 Purchases (1) 257,671 — 72,582 45,215 Sales (1) (49,511 ) — (18,624 ) — Settlements (1) (234,552 ) — (15,084 ) (60,966 ) Transfers into Level 3 35,042 — 5,515 75,752 Transfers out of Level 3 (12,973 ) — (89,621 ) (142,575 ) Fair value, end of period $ 1,272,020 $ 525,365 $ 117,995 $ 145,197 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (1,213 ) $ 9,731 $ (155 ) $ 556 Investment related gains (losses), net (2,788 ) — (346 ) — For the nine months ended September 30, 2017 (continued): Fixed maturity securities available-for-sale 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 (348 ) (68 ) (1 ) Investment related gains (losses), net (595 ) — — — Included in other comprehensive income (57 ) 269 (228 ) (210 ) Purchases (1) — 370 — 495 Sales (1) (3,720 ) — — — Settlements (1) (5,403 ) (1,528 ) (309 ) (672 ) Transfers into Level 3 — — 7,295 — Transfers out of Level 3 (10,132 ) — (6,844 ) (6,853 ) Fair value, end of period $ 1,947 $ 23,251 $ 41,512 $ 5,628 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ — $ (348 ) $ (68 ) $ (1 ) For the nine months ended September 30, 2017 (continued): Short-term Investments Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 3,346 $ (22,529 ) $ 26,958 $ (990,308 ) $ (2,462 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 106,854 — 9,005 — Interest credited — — — (20,408 ) — Included in other comprehensive income 1 — 3,689 — 1 Other revenues — — 7,180 — (922 ) Purchases (1) 3,520 — — (51,276 ) — Settlements (1) (272 ) — — 63,047 1,700 Transfers out of Level 3 (3,236 ) — — — — Fair value, end of period $ 3,359 $ 84,325 $ 37,827 $ (989,940 ) $ (1,683 ) Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment related gains (losses), net $ — $ 106,854 $ — $ 2,934 $ — Other revenues — — 7,180 — (922 ) Interest credited — — — (83,456 ) — (1) The amount reported within purchases, sales and settlements is the purchase price (for purchases) and the sales/settlement proceeds (for sales and settlements) based upon the actual date purchased or sold/settled. Items purchased and sold/settled in the same period are excluded from the rollforward. The Company had no issuances during the period. Nonrecurring Fair Value Measurements The following table presents information for assets measured at an estimated fair value on a nonrecurring basis during the periods presented and and still held at the reporting date (for example, when there is evidence of impairment). The estimated fair values for these assets were determined using significant unobservable inputs (Level 3). Carrying Value After Measurement Net Investment Gains (Losses) At September 30, Three months ended September 30, Nine months ended September 30, (dollars in thousands) 2018 2017 2018 2017 2018 2017 Limited partnership interests (1) $ 2,246 $ 4,656 $ (1,860 ) $ (896 ) $ (1,860 ) $ (7,204 ) Private equities (2) — 106 — (531 ) — (531 ) (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. (2) The fair value of the Company’s private equity investments is based on external valuation models. 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 September 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. September 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 $ 4,779,074 $ 4,652,481 $ — $ — $ 4,652,481 $ — Policy loans 1,320,050 1,320,050 — 1,320,050 — — Funds withheld at interest 5,833,925 6,040,671 — — 6,040,671 — Cash and cash equivalents 1,073,209 1,073,209 1,073,209 — — — Short-term investments 43,877 43,877 43,877 — — — Other invested assets 842,626 839,280 5,618 71,401 382,284 379,977 Accrued investment income 455,296 455,296 — 455,296 — — Liabilities: Interest-sensitive contract liabilities $ 13,319,348 $ 13,113,427 $ — $ — $ 13,113,427 $ — Long-term debt 2,787,975 2,850,344 — — 2,850,344 — Collateral finance and securitization notes 710,792 652,380 — — 652,380 — 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	9 Months Ended
	Sep. 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 September 30, Nine months ended September 30, Revenues: 2018 2017 2018 2017 U.S. and Latin America: Traditional $ 1,547,790 $ 1,521,383 $ 4,601,631 $ 4,532,584 Financial Solutions 290,848 264,170 734,148 834,992 Total 1,838,638 1,785,553 5,335,779 5,367,576 Canada: Traditional 295,962 281,095 910,480 814,643 Financial Solutions 12,168 12,430 37,034 36,240 Total 308,130 293,525 947,514 850,883 Europe, Middle East and Africa: Traditional 357,059 360,972 1,123,379 1,024,978 Financial Solutions 91,664 77,041 280,482 230,435 Total 448,723 438,013 1,403,861 1,255,413 Asia Pacific: Traditional 578,035 561,660 1,763,094 1,628,419 Financial Solutions 16,167 16,932 54,005 55,368 Total 594,202 578,592 1,817,099 1,683,787 Corporate and Other 37,838 49,627 92,893 125,667 Total $ 3,227,531 $ 3,145,310 $ 9,597,146 $ 9,283,326 Three months ended September 30, Nine months ended September 30, Income (loss) before income taxes: 2018 2017 2018 2017 U.S. and Latin America: Traditional $ 116,328 $ 160,512 $ 191,198 $ 281,066 Financial Solutions 87,073 89,118 236,882 299,689 Total 203,401 249,630 428,080 580,755 Canada: Traditional 21,149 28,789 66,661 80,953 Financial Solutions 1,646 4,472 8,381 12,489 Total 22,795 33,261 75,042 93,442 Europe, Middle East and Africa: Traditional 18,370 15,421 40,259 40,751 Financial Solutions 56,205 30,953 160,738 91,776 Total 74,575 46,374 200,997 132,527 Asia Pacific: Traditional 62,007 26,564 143,756 121,574 Financial Solutions 206 (229 ) 8,365 11,020 Total 62,213 26,335 152,121 132,594 Corporate and Other (40,323 ) (15,438 ) (148,366 ) (51,997 ) Total $ 322,661 $ 340,162 $ 707,874 $ 887,321 Assets: September 30, 2018 December 31, 2017 U.S. and Latin America: Traditional $ 19,148,790 $ 18,603,423 Financial Solutions 19,251,832 15,959,206 Total 38,400,622 34,562,629 Canada: Traditional 4,210,051 4,161,452 Financial Solutions 146,374 126,372 Total 4,356,425 4,287,824 Europe, Middle East and Africa: Traditional 3,573,449 3,099,495 Financial Solutions 4,585,297 5,274,993 Total 8,158,746 8,374,488 Asia Pacific: Traditional 5,312,822 4,915,442 Financial Solutions 1,181,954 1,198,585 Total 6,494,776 6,114,027 Corporate and Other 5,562,073 7,175,850 Total $ 62,972,642 $ 60,514,818

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 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 September 30, 2018 and December 31, 2017 are presented in the following table (dollars in thousands): September 30, 2018 December 31, 2017 Limited partnership interests and joint ventures $ 578,944 $ 485,197 Commercial mortgage loans 120,571 40,815 Bank loans and private placements 101,992 60,472 Equity release mortgages 213,459 153,937 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 September 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 September 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 September 30, 2018 and December 31, 2017 are reflected in the following table (dollars in thousands): September 30, 2018 December 31, 2017 Treaty guarantees $ 1,073,184 $ 1,047,449 Treaty guarantees, net of assets in trust 966,099 926,393 Securities borrowing and repurchase arrangements 276,190 294,325 Financing arrangements 69,221 86,183 Lease obligations 881 1,662

Income Tax

Income Tax	9 Months Ended
	Sep. 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 nine months ended September 30, 2018 and 2017 , respectively (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Tax provision at U.S. statutory rate $ 67,759 $ 119,057 $ 148,654 $ 310,562 Increase (decrease) in income taxes resulting from: U.S. Tax Reform provisional adjustments 664 — (2,685 ) — U.S. Tax Reform valuation allowance adjustments (58,949 ) — (59,139 ) — Foreign tax rate differing from U.S. tax rate 7,537 (3,635 ) 8,795 (14,049 ) Differences in tax bases in foreign jurisdictions (2,371 ) 2,126 (9,264 ) (14,633 ) Deferred tax valuation allowance (5,334 ) (2,501 ) 5,357 11,627 Amounts related to tax audit contingencies 1,851 299 650 (873 ) Corporate rate changes (166 ) (1,139 ) 30 (2,332 ) Subpart F (99 ) 64 211 1,390 Foreign tax credits (544 ) 1,230 (1,003 ) (834 ) Global intangible low-taxed income, net of credit 7,624 — 11,916 — Equity compensation excess benefit (817 ) (2,762 ) (5,067 ) (7,226 ) Return to provision adjustments 4,213 452 4,108 133 Other, net 94 (620 ) (492 ) (1,737 ) Total provision for income taxes $ 21,462 $ 112,571 $ 102,071 $ 282,028 Effective tax rate 6.7 % 33.1 % 14.4 % 31.8 % 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”); (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. The SEC issued Staff Accounting Bulletin 118 (“SAB 118”), which provides guidance on accounting for the tax effects of U.S. Tax Reform. SAB 118 provides a measurement period that should not extend beyond one year from U.S. Tax Reform enactment date for companies to complete the accounting under Accounting Standards Codification 740 (“ASC 740”). In accordance with SAB 118, a company must reflect the income tax effects of those aspects of U.S. Tax Reform for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of U.S. Tax Reform is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of U.S. Tax Reform. The Company calculated a provisional estimate of the impact of U.S. Tax Reform for its 2017 financial statements. As of September 30, 2018, the Company has finalized certain aspects of U.S. Tax Reform including computing the pretax deferred tax items upon which the change in tax rate was applied, the one-time transition tax on unrepatriated earnings of foreign subsidiaries and the adoption of Accounting Standards Update 2018-02 (“ASU 2018-02”). The Company has refined provisional estimates related to excessive employee remuneration, which may be further refined during the fourth quarter. The Company also continues to monitor the issuance of new guidance in the form of Treasury Regulations or Notices which could impact the provisional balances recorded as of December 31, 2017. In addition to the amounts in the table above, the Company recorded an additional adjustment in the third quarter of 2018 related to ASU 2018-02, decreasing accumulated other comprehensive income and increasing retained earnings by approximately $2.6 million . The Company provisionally estimated there would be no one-time transition tax on unrepatriated earnings of foreign subsidiaries. Upon review of the Proposed Treasury Regulations issued during the quarter and completion of the accumulated and current earnings and profits calculations of the Company’s foreign subsidiaries, no adjustment to the provisional estimate of the transition tax on unrepatriated earnings is necessary. 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. The Company continues to gather information and monitor guidance that may change the Company’s interpretation of the law and hence may result in a refinement to the calculation and changes to this amount. 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 base erosion percentage threshold for application of the BEAT; therefore, the Company has not established an additional BEAT liability as of September 30, 2018. The Company continues to gather information and monitor guidance that may change the Company’s interpretation of the law and hence may result in a refinement to the calculation and changes to this amount. The effective tax rate for the third quarter and first nine months of 2018 were lower than the U.S. Statutory rate of 21.0% primarily as a result of the release of a valuation allowance on foreign tax credits, which was partially offset by income earned in jurisdictions with statutory rates higher than the U.S. tax rate and tax expense related to GILTI. During the third quarter the Company released an uncertain tax position due to the expiration of the statute of limitations and established a new position. The foreign tax credits were used to offset the new uncertain tax liability, resulting in a valuation allowance no longer being necessary. $58.9 million of the release of the valuation allowance was previously established as part of U.S. Tax Reform. The effective tax rates for the third quarter and first nine months of 2017 were lower than the U.S. Statutory rate of 35% primarily as a result of income generated in non-U.S. jurisdictions with lower tax rates than the U.S. The first nine months of 2017 also included a reduction related to differences in tax bases in foreign jurisdictions and a tax benefit from the filing of amended returns, which was partially offset with a valuation allowance established related to amended return filings.

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 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 nine months ended September 30, 2018 and 2017 were as follows (dollars in thousands): Pension Benefits Other Benefits Three months ended September 30, Three months ended September 30, 2018 2017 2018 2017 Service cost $ 3,106 $ 2,699 $ 999 $ 465 Interest cost 1,341 1,314 680 459 Expected return on plan assets (1,884 ) (1,554 ) — — Amortization of prior service cost (credit) 82 85 (328 ) (675 ) Amortization of prior actuarial losses 929 1,081 937 580 Settlements — 256 — — Net periodic benefit cost $ 3,574 $ 3,881 $ 2,288 $ 829 Pension Benefits Other Benefits Nine months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Service cost $ 9,330 $ 8,098 $ 2,271 $ 1,907 Interest cost 4,028 3,943 1,739 1,589 Expected return on plan assets (5,651 ) (4,662 ) — — Amortization of prior service cost (credit) 247 254 (986 ) (986 ) Amortization of prior actuarial losses 2,792 3,244 1,933 1,494 Settlements — 769 — — Net periodic benefit cost $ 10,746 $ 11,646 $ 4,957 $ 4,004

Reinsurance

Reinsurance	9 Months Ended
	Sep. 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 September 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 September 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 limits to affiliated subsidiaries. The following table presents information for the Company’s reinsurance ceded receivable assets, including the respective amount and A.M. Best rating for each reinsurer representing in excess of five percent of the total as of September 30, 2018 or December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 Reinsurer A.M. Best Rating Amount % of Total Amount % of Total Reinsurer A A+ $ 303,942 39.5 $ 301,478 38.6 % Reinsurer B A+ 203,702 26.5 203,898 26.1 Reinsurer C A 67,599 8.8 67,723 8.7 Reinsurer D A+ 41,049 5.3 40,528 5.2 Reinsurer E A++ 35,090 4.6 40,592 5.2 Other reinsurers 117,942 15.3 127,808 16.2 Total $ 769,324 100.0 % $ 782,027 100.0 % Included in the total reinsurance ceded receivables balance were $269.1 million and $243.8 million of claims recoverable, of which $6.7 million and $1.9 million were in excess of 90 days past due, as of September 30, 2018 and December 31, 2017 , respectively.

Financing Activities

Financing Activities	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	Financing Activities On August 21, 2018 the Company entered into a new syndicated revolving credit facility with a five year term and an overall capacity of $850.0 million , replacing its existing $850.0 million syndicated revolving credit facility, which was scheduled to mature in September 2019.

New Accounting Standards

New Accounting Standards	9 Months Ended
	Sep. 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. The adjustments to the Company’s deferred tax liabilities was a provisional amount as defined in the SEC’s SAB 118, issued in December 2017 to address complexities in completing the calculations resulting from the U.S. Tax Cuts and Jobs Act of 2017. SAB 118 provides guidance on accounting for the effects of the U.S. Tax and Jobs Act of 2017 when the Company’s process is incomplete, and permits a final determination to be made within a measurement period not to exceed one year from the enactment date. During 2018, the Company continued to evaluate and gather additional information to account for the effects of the Tax Cuts and Jobs Act of 2017, including the preparation of and filing of its U.S. tax returns to more precisely compute the pretax deferred tax items and the impact of adopting the new guidance. As part of this process the Company recorded an additional adjustment in 2018 decreasing accumulated other comprehensive income and increasing retained earnings of approximately $2.6 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. Fair Value Measurement This guidance is part of the FASB’s disclosure framework project and eliminates certain disclosure requirements for fair value measurement, requires entities to disclose new information and modifies existing disclosure requirements. Early adoption is permitted. January 1, 2020 Certain disclosure changes in the new guidance will be applied prospectively in the year of adoption. The remaining changes in the new guidance will be applied retrospectively to all periods presented in the year of adoption. The Company is currently evaluating the impact of this amendment on its consolidated financial statements. Financial Services - Insurance This guidance significantly changes how insurers account for long-duration insurance contracts. The new guidance will require insurers to review and update, if necessary, the assumptions used to measure insurance liabilities periodically, rather than retain assumptions used at contract inception. The updated guidance also changes the recognition and measurement of deferred acquisition costs (DAC) and created a new category of benefit features called market risk benefits (MRB) that will be measured at fair value. The guidance also significantly expands the disclosure requirements for long-duration contracts. January 1, 2021 The guidance on measuring the liabilities for future policy benefits and DAC will be adopted on a modified retrospective basis as of the earliest period presented in the year of adoption. The guidance on MRB will be adopted on a retrospective basis as of the earliest period presented in the year of adoption. The Company is currently evaluating the impact of this amendment on its consolidated financial statements but anticipates the updated guidance will likely have a material impact on the measurement and recognition of its long-duration insurance contracts. Compensation - Retirement Benefits - Defined Benefit Plans - General This guidance is part of the FASB’s disclosure framework project and eliminates certain disclosure requirements for defined benefit pension and other postretirement plans. Early adoption is permitted. January 1, 2021 This new guidance will be applied retrospectively to all periods presented in the year of adoption. The Company is currently evaluating the impact of this amendment on its consolidated financial statements.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 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 September 30, Nine months ended September 30, 2018 2017 2018 2017 Earnings: Net income (numerator for basic and diluted calculations) $ 301,199 $ 227,591 $ 605,803 $ 605,293 Shares: Weighted average outstanding shares (denominator for basic calculation) 63,279 64,488 63,941 64,430 Equivalent shares from outstanding stock options 1,017 1,165 1,189 1,174 Denominator for diluted calculation 64,296 65,653 65,130 65,604 Earnings per share: Basic $ 4.76 $ 3.53 $ 9.47 $ 9.39 Diluted $ 4.68 $ 3.47 $ 9.30 $ 9.23
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 thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Excluded from common equivalent shares: Stock options 227 87 349 296 Performance contingent shares 276 307 256 293

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 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 — 1,750,295 (1,750,295 ) Stock-based compensation (1) — (249,068 ) 249,068 Balance, September 30, 2018 79,137,758 16,186,890 62,950,868 Issued Held In Treasury Outstanding Balance, December 31, 2016 79,137,758 14,835,256 64,302,502 Common stock acquired — 208,680 (208,680 ) Stock-based compensation (1) — (274,449 ) 274,449 Balance, September 30, 2017 79,137,758 14,769,487 64,368,271 (1) Represents net shares issued from treasury pursuant to the Company’s equity-based compensation programs.
Components of Accumulated Other Comprehensive Income	The balance of and changes in each component of accumulated other comprehensive income (loss) (“AOCI”) for the nine months ended September 30, 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 (24,977 ) (1,638,146 ) (3,391 ) (1,666,514 ) Amounts reclassified to (from) AOCI — 79,505 3,986 83,491 Deferred income tax benefit (expense) (5,398 ) 340,332 (164 ) 334,770 Adoption of new accounting standard (2,573 ) — — (2,573 ) Balance, September 30, 2018 $ (119,298 ) $ 982,352 $ (50,249 ) $ 812,805 Accumulated Currency Translation Adjustments Unrealized Appreciation (Depreciation) of Investments (1) Pension and Postretirement Benefits Total Balance, December 31, 2016 $ (172,541 ) $ 1,355,033 $ (43,163 ) $ 1,139,329 Other comprehensive income (loss) before reclassifications 23,117 671,564 (191 ) 694,490 Amounts reclassified to (from) AOCI — (51,407 ) 4,006 (47,401 ) Deferred income tax benefit (expense) 44,968 (204,287 ) (1,342 ) (160,661 ) Balance, September 30, 2017 $ (104,456 ) $ 1,770,903 $ (40,690 ) $ 1,625,757 (1) Includes cash flow hedges of $29,043 and $2,619 as of September 30, 2018 and December 31, 2017 , respectively, and $347 and $(2,496) as of September 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 nine months ended September 30, 2018 and 2017 (dollars in thousands): Amount Reclassified from AOCI Three months ended September 30, Nine months ended September 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 $ (21,249 ) $ 10,515 $ (60,347 ) $ 39,032 Investment related gains (losses), net Cash flow hedges - Interest rate 234 — (108 ) — (1) Cash flow hedges - Currency/Interest rate 50 230 270 560 (1) Cash flow hedges - Forward bond purchase commitments — 224 — 286 (1) Deferred policy acquisition costs attributed to unrealized gains and losses (4,893 ) 1,116 (19,320 ) 11,529 (2) Total (25,858 ) 12,085 (79,505 ) 51,407 Provision for income taxes 5,355 (3,991 ) 16,978 (16,015 ) Net unrealized gains (losses), net of tax $ (20,503 ) $ 8,094 $ (62,527 ) $ 35,392 Amortization of defined benefit plan items: Prior service cost (credit) $ 246 $ 590 $ 739 $ 732 (3) Actuarial gains/(losses) (1,866 ) (1,661 ) (4,725 ) (4,738 ) (3) Total (1,620 ) (1,071 ) (3,986 ) (4,006 ) Provision for income taxes 340 375 837 1,402 Amortization of defined benefit plans, net of tax $ (1,280 ) $ (696 ) $ (3,149 ) $ (2,604 ) Total reclassifications for the period $ (21,783 ) $ 7,398 $ (65,676 ) $ 32,788 (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)	9 Months Ended
	Sep. 30, 2018
Investments [Abstract]
Available For Sale Securities	The following table provides information relating to investments in fixed maturity securities by sector as of September 30, 2018 (dollars in thousands): September 30, 2018: Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value % of Total Other-than- Available-for-sale: Corporate $ 24,271,467 $ 594,444 $ 416,413 $ 24,449,498 62.7 % $ — Canadian government 2,902,433 1,138,426 4,109 4,036,750 10.3 — RMBS 1,816,949 14,235 50,422 1,780,762 4.6 — ABS 1,867,650 10,312 14,945 1,863,017 4.8 275 CMBS 1,282,015 8,403 16,884 1,273,534 3.3 — U.S. government 1,500,703 6,359 94,653 1,412,409 3.6 — State and political subdivisions 889,218 36,410 13,637 911,991 2.3 — Other foreign government 3,220,697 98,574 42,020 3,277,251 8.4 — Total fixed maturity securities $ 37,751,132 $ 1,907,163 $ 653,083 $ 39,005,212 100.0 % $ 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Fixed maturity securities pledged as collateral $ 67,899 $ 69,792 $ 72,542 $ 75,622 Fixed maturity securities received as collateral n/a 592,146 n/a 590,417 Assets in trust held to satisfy collateral requirements 19,263,724 19,670,559 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 September 30, 2018 and December 31, 2017 (dollars in thousands). September 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 $ 1,158,326 $ 1,833,972 $ 1,119,337 $ 1,917,996 Canadian province of Ontario 951,186 1,225,712 939,837 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 September 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 $ 986,289 $ 993,352 Due after one year through five years 7,797,732 7,888,116 Due after five years through ten years 9,311,737 9,407,186 Due after ten years 14,688,760 15,799,245 Asset and mortgage-backed securities 4,966,614 4,917,313 Total $ 37,751,132 $ 39,005,212
Fixed Maturity Holdings Industry Types Weighted Average Credit Ratings [Table Text Block]	The tables below show the major industry types of the Company’s corporate fixed maturity holdings as of September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018: Estimated Amortized Cost Fair Value % of Total Finance $ 8,561,885 $ 8,564,254 35.1 % Industrial 12,632,502 12,753,024 52.1 Utility 3,077,080 3,132,220 12.8 Total $ 24,271,467 $ 24,449,498 100.0 % 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 September 30, Nine months ended September 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 2,866 fixed maturity securities as of September 30, 2018 , where the estimated fair value had declined and remained below amortized cost by the indicated amount (dollars in thousands): September 30, 2018 Gross Unrealized Losses % of Total Less than 20% $ 640,481 98.1 % 20% or more for less than six months 309 — 20% or more for six months or greater 12,293 1.9 Total $ 653,083 100.0 % 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 2,866 fixed maturity securities that have estimated fair values below amortized cost as of September 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 September 30, 2018: Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Investment grade securities: Corporate $ 10,117,970 $ 303,926 $ 1,290,804 $ 81,236 $ 11,408,774 $ 385,162 Canadian government 58,816 1,211 107,167 2,736 165,983 3,947 RMBS 931,044 23,339 528,739 27,063 1,459,783 50,402 ABS 680,900 8,650 262,544 6,243 943,444 14,893 CMBS 555,716 8,304 207,943 8,580 763,659 16,884 U.S. government 197,114 3,913 1,002,661 90,740 1,199,775 94,653 State and political subdivisions 261,456 6,722 90,649 6,915 352,105 13,637 Other foreign government 1,034,417 24,666 297,566 11,062 1,331,983 35,728 Total investment grade securities 13,837,433 380,731 3,788,073 234,575 17,625,506 615,306 Below investment grade securities: Corporate 539,521 23,955 77,675 7,296 617,196 31,251 Canadian government 2,328 162 — — 2,328 162 RMBS — — 1,102 20 1,102 20 ABS — — 1,110 52 1,110 52 Other foreign government 140,692 5,931 6,410 361 147,102 6,292 Total below investment grade securities 682,541 30,048 86,297 7,729 768,838 37,777 Total fixed maturity securities $ 14,519,974 $ 410,779 $ 3,874,370 $ 242,304 $ 18,394,344 $ 653,083 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 September 30, Nine months ended September 30, 2018 2017 2018 2017 Fixed maturity securities available-for-sale $ 378,669 $ 359,157 $ 1,121,496 $ 1,039,392 Equity securities 1,319 942 3,710 3,296 Mortgage loans on real estate 54,424 50,040 155,083 138,829 Policy loans 14,730 15,404 44,285 45,870 Funds withheld at interest 108,232 102,144 270,094 327,089 Short-term investments and cash and cash equivalents 3,067 1,977 9,276 5,266 Other invested assets 35,594 46,653 80,207 87,192 Investment income 596,035 576,317 1,684,151 1,646,934 Investment expense (23,293 ) (19,399 ) (67,019 ) (57,114 ) Investment income, net of related expenses $ 572,742 $ 556,918 $ 1,617,132 $ 1,589,820
Gain Loss On Investments	Investment related gains (losses), net consist of the following (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Fixed maturity securities available for sale: Other-than-temporary impairment losses $ (10,705 ) $ (390 ) $ (14,055 ) $ (20,980 ) Gain on investment activity 20,040 19,512 52,146 91,611 Loss on investment activity (37,880 ) (7,593 ) (94,194 ) (26,577 ) Equity securities: Other-than-temporary impairment losses — (889 ) — (889 ) Gain on investment activity 3,932 10 4,429 24 Loss on investment activity (174 ) (85 ) (1,124 ) (4,135 ) Change in unrealized gains (losses) recognized in earnings 3,539 — (7,564 ) — Other impairment losses and change in mortgage loan provision (6,566 ) (2,446 ) (8,235 ) (9,220 ) Derivatives and other, net 7,797 14,534 37,538 109,637 Total investment related gains (losses), net $ (20,017 ) $ 22,653 $ (31,059 ) $ 139,471
Schedule of Repurchase Agreements [Table Text Block]	The following table includes the amount of borrowed securities, securities lent and securities collateral received as part of the securities lending program and repurchased/reverse repurchased securities pledged and received as of September 30, 2018 and December 31, 2017 (dollars in thousands). September 30, 2018 December 31, 2017 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Borrowed securities $ 353,650 $ 370,323 $ 358,875 $ 377,820 Securities lending: Securities loaned 101,965 102,489 117,246 121,551 Securities received n/a 112,000 n/a 128,000 Repurchase program/reverse repurchase program: Securities pledged 408,679 404,905 413,819 428,344 Securities received n/a 400,515 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 September 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. September 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 $ — $ — $ — $ 102,489 $ 102,489 Total — — — 102,489 102,489 Repurchase transactions: Corporate — — — 132,228 132,228 U.S. government — — — 219,906 219,906 Foreign government — — — 52,771 52,771 Other — — — — — Total — — — 404,905 404,905 Total transactions $ — $ — $ — $ 507,394 $ 507,394 Gross amount of recognized liabilities for securities lending and repurchase transactions in preceding table $ 541,411 Amounts related to agreements not included in offsetting disclosure $ 34,017 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 Property type: Carrying Value % of Total Carrying Value % of Total Office building $ 1,633,887 34.1 % $ 1,487,392 33.6 % Retail 1,365,157 28.5 1,270,676 28.8 Industrial 983,553 20.5 938,612 21.3 Apartment 543,917 11.3 510,052 11.6 Other commercial 267,712 5.6 206,439 4.7 Recorded investment 4,794,226 100.0 % 4,413,171 100.0 % Unamortized balance of loan origination fees and expenses (4,786 ) (3,254 ) Valuation allowances (10,366 ) (9,384 ) Total mortgage loans on real estate $ 4,779,074 $ 4,400,533
Mortgage Loans Classified By Contractual Maturity Date [Table Text Block]	The maturities of mortgage loans as of September 30, 2018 and December 31, 2017 are as follows (dollars in thousands): September 30, 2018 December 31, 2017 Recorded Investment % of Total Recorded Investment % of Total Due within five years $ 1,216,241 25.4 % $ 1,091,066 24.8 % Due after five years through ten years 2,738,400 57.1 2,516,872 57.0 Due after ten years 839,585 17.5 805,233 18.2 Total $ 4,794,226 100.0 % $ 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 September 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 September 30, 2018: Loan-to-Value Ratio 0% - 59.99% $ 2,146,401 $ 63,794 $ 43,486 $ 25,724 $ 2,279,405 47.6 % 60% - 69.99% 1,666,525 117,726 62,617 — 1,846,868 38.5 70% - 79.99% 386,137 70,884 76,054 — 533,075 11.1 Greater than 80% 108,233 22,429 4,216 — 134,878 2.8 Total $ 4,307,296 $ 274,833 $ 186,373 $ 25,724 $ 4,794,226 100.0 % 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 31-60 days past due $ — $ 17,100 61-90 days past due — 2,056 Total past due — 19,156 Current 4,794,226 4,394,015 Total $ 4,794,226 $ 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 Mortgage loans: Individually measured for impairment $ 30,629 $ 5,858 Collectively measured for impairment 4,763,597 4,407,313 Recorded investment $ 4,794,226 $ 4,413,171 Valuation allowances: Individually measured for impairment $ — $ — Collectively measured for impairment 10,366 9,384 Total valuation allowances $ 10,366 $ 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 nine months ended September 30, 2018 and 2017 is as follows (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Balance, beginning of period $ 9,706 $ 8,156 $ 9,384 $ 7,685 Provision (release) 656 977 986 1,444 Translation adjustment 4 4 (4 ) 8 Balance, end of period $ 10,366 $ 9,137 $ 10,366 $ 9,137
Impaired Financing Receivables Table	Information regarding the portion of the Company’s mortgage loans that were impaired as of September 30, 2018 and December 31, 2017 is as follows (dollars in thousands): Unpaid Principal Balance Recorded Investment Related Allowance Carrying Value September 30, 2018: Impaired mortgage loans with no valuation allowance recorded $ 30,660 $ 30,629 $ — $ 30,629 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 30,660 $ 30,629 $ — $ 30,629 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 September 30, 2018 2017 Average (1) Interest Income Average Recorded Investment (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 30,641 $ 346 $ 3,967 $ 33 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 30,641 $ 346 $ 3,967 $ 33 Nine months ended September 30, 2018 2017 Average (1) Interest Income Average (1) Interest Income Impaired mortgage loans with no valuation allowance recorded $ 22,641 $ 650 $ 3,062 $ 100 Impaired mortgage loans with valuation allowance recorded — — — — Total impaired mortgage loans $ 22,641 $ 650 $ 3,062 $ 100 (1) Average recorded investment represents the average loan balances as of the beginning of period and all subsequent quarterly end of period balances.
Schedule Of Other Invested Assets [Table Text Block]	Carrying values of these assets as of September 30, 2018 and December 31, 2017 are as follows (dollars in thousands): September 30, 2018 December 31, 2017 Limited partnership interests and real estate joint ventures $ 924,006 $ 781,124 Equity release mortgages 383,450 219,940 Derivatives 101,124 137,613 FVO contractholder-directed unit-linked investments 212,315 218,541 Other 86,084 148,114 Total other invested assets $ 1,706,979 $ 1,505,332

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 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 September 30, 2018 and December 31, 2017 (dollars in thousands): September 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 $ 1,074,173 $ 37,238 $ 1,818 $ 996,204 $ 59,809 $ 2,372 Financial futures 347,916 — — 412,438 — — Foreign currency forwards — — — 6,030 — 28 Consumer price index swaps 409,023 127 2,836 221,932 — 2,160 Credit default swaps 1,373,300 6,759 114 961,200 8,319 1,651 Equity options 571,845 19,372 — 632,251 23,271 — Longevity swaps 928,320 46,090 — 960,400 40,659 — Mortality swaps 25,000 — 308 — — 1,683 Synthetic guaranteed investment contracts 10,844,558 — — 10,052,576 — — Embedded derivatives in: Modified coinsurance or funds withheld arrangements — 142,529 — — 122,194 — Indexed annuity products — — 815,970 — — 861,758 Variable annuity products — — 90,229 — — 152,470 Total non-hedging derivatives 15,574,135 252,115 911,275 14,243,031 254,252 1,022,122 Derivatives designated as hedging instruments: Interest rate swaps 435,000 99 20,579 435,000 — 20,389 Foreign currency swaps 537,249 46,141 3,770 672,921 65,207 8,496 Foreign currency forwards 834,238 8,948 2,067 553,175 1,265 7,720 Total hedging derivatives 1,806,487 55,188 26,416 1,661,096 66,472 36,605 Total derivatives $ 17,380,622 $ 307,303 $ 937,691 $ 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 September 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 September 30, 2018: Derivative assets $ 164,774 $ (17,560 ) $ 147,214 $ — $ (159,194 ) $ (11,980 ) Derivative liabilities 31,492 (17,560 ) 13,932 (61,293 ) (13,400 ) (60,761 ) 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 September 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 September 30, 2018: Derivative assets $ 164,774 $ (17,560 ) $ 147,214 $ — $ (159,194 ) $ (11,980 ) Derivative liabilities 31,492 (17,560 ) 13,932 (61,293 ) (13,400 ) (60,761 ) 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 September 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 September 30, 2018: Foreign currency swaps Foreign-denominated fixed maturity securities $ (2,258 ) $ 2,832 For the three months ended September 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 2,100 $ (2,100 ) For the nine months ended September 30, 2018: Foreign currency swaps Foreign-denominated fixed maturity securities $ (5,284 ) $ 9,666 For the nine months ended September 30, 2017: Foreign currency swaps Foreign-denominated fixed maturity securities $ 9,541 $ (9,541 )
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table presents the components of AOCI, before income tax, and the condensed consolidated income statement classification where the gain or loss is recognized related to cash flow hedges for the three and nine months ended September 30, 2018 and 2017 (dollars in thousands): Three months ended September 30, 2018 2017 Balance beginning of period $ 22,656 $ 7,690 Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges 6,671 (6,889 ) Amounts reclassified to investment related (gains) losses, net — (183 ) Amounts reclassified to investment income (50 ) (271 ) Amounts reclassified to interest expense (234 ) — Balance end of period $ 29,043 $ 347 Nine months ended September 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 26,586 3,689 Amounts reclassified to investment related (gains) losses, net — (142 ) Amounts reclassified to investment income (270 ) (704 ) Amounts reclassified to interest expense 108 — Balance end of period $ 29,043 $ 347
Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The following table presents the effective portion of derivatives in cash flow hedging relationships on the condensed consolidated statements of income and the condensed consolidated statements of comprehensive income for the three and nine months ended September 30, 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 September 30, 2018: Interest rate $ 7,490 $ — $ — $ 234 Currency/Interest rate (819 ) — 50 — Total $ 6,671 $ — $ 50 $ 234 For the three months ended September 30, 2017: Interest rate $ (8,421 ) $ — $ — $ — Currency/Interest rate 1,544 — 230 — Forward bond purchase commitments (12 ) 183 41 — Total $ (6,889 ) $ 183 $ 271 $ — For the nine months ended September 30, 2018: Interest rate $ 27,217 $ — $ — $ (108 ) Currency/Interest rate (631 ) — 270 — Total $ 26,586 $ — $ 270 $ (108 ) For the nine months ended September 30, 2017: Interest rate $ (6,205 ) $ — $ — $ — Currency/Interest rate 9,894 — 560 — Forward bond purchase commitments — 142 144 — Total $ 3,689 $ 142 $ 704 $ —
Schedule of Net Investment Hedges, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The following table illustrates the Company’s net investments in foreign operations (“NIFO”) hedges for the three and nine months ended September 30, 2018 and 2017 (dollars in thousands): Derivative Gains (Losses) Deferred in AOCI For the three months ended September 30, For the nine months ended September 30, Type of NIFO Hedge (1) (2) 2018 2017 2018 2017 Foreign currency swaps $ (5,877 ) $ (35,198 ) $ 11,125 $ (60,723 ) Foreign currency forwards (11,562 ) 4,627 11,737 8,785 Total $ (17,439 ) $ (30,571 ) $ 22,862 $ (51,938 ) (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 nine months ended September 30, 2018 and 2017 is as follows (dollars in thousands): Gain (Loss) for the three months ended September 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2018 2017 Interest rate swaps Investment related gains (losses), net $ (12,228 ) $ 641 Financial futures Investment related gains (losses), net (6,544 ) (8,890 ) Foreign currency forwards Investment related gains (losses), net (58 ) 24 CPI swaps Investment related gains (losses), net (4,223 ) 220 Credit default swaps Investment related gains (losses), net 4,689 4,137 Equity options Investment related gains (losses), net (9,793 ) (8,295 ) Longevity swaps Other revenues 2,426 3,334 Mortality swaps Other revenues 473 (132 ) Subtotal (25,258 ) (8,961 ) Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net (2,081 ) 23,044 Indexed annuity products Interest credited (25,347 ) (13,133 ) Variable annuity products Investment related gains (losses), net 32,133 (6,205 ) Total non-hedging derivatives $ (20,553 ) $ (5,255 ) Gain (Loss) for the nine months ended September 30, Type of Non-hedging Derivative Income Statement Location of Gain (Loss) 2018 2017 Interest rate swaps Investment related gains (losses), net $ (47,399 ) $ 12,318 Financial futures Investment related gains (losses), net (7,312 ) (28,107 ) Foreign currency forwards Investment related gains (losses), net 3 577 CPI swaps Investment related gains (losses), net (996 ) 211 Credit default swaps Investment related gains (losses), net 5,371 15,374 Equity options Investment related gains (losses), net (15,207 ) (34,757 ) Longevity swaps Other revenues 6,983 7,180 Mortality swaps Other revenues (326 ) (921 ) Subtotal (58,883 ) (28,125 ) Embedded derivatives in: Modified coinsurance or funds withheld arrangements Investment related gains (losses), net 20,335 106,854 Indexed annuity products Interest credited 6,523 (35,490 ) Variable annuity products Investment related gains (losses), net 62,242 16,518 Total non-hedging derivatives $ 30,217 $ 59,757
Disclosure Of Credit Derivatives	The following table presents the estimated fair value, maximum amount of future payments and weighted average years to maturity of credit default swaps sold by the Company at September 30, 2018 and December 31, 2017 (dollars in thousands): September 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 $ 2,470 $ 152,000 2.5 $ 3,128 $ 162,000 2.9 Subtotal 2,470 152,000 2.5 3,128 162,000 2.9 BBB+/BBB/BBB- Single name credit default swaps 4,220 343,700 2.4 4,469 361,700 2.9 Credit default swaps referencing indices (80 ) 642,600 3.4 (55 ) 422,600 4.0 Subtotal 4,140 986,300 3.1 4,414 784,300 3.5 BB+/BB/BB- Single name credit default swaps 32 15,000 1.0 30 5,000 1.5 Subtotal 32 15,000 1.0 30 5,000 1.5 Total $ 6,642 $ 1,153,300 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 nine months ended September 30, 2018 and 2017 are reflected in the following table (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Embedded derivatives in modco or funds withheld arrangements included in investment related gains $ (2,081 ) $ 23,044 $ 20,335 $ 106,854 After the associated amortization of DAC and taxes, the related amounts included in net income (1,320 ) 7,515 11,517 36,300 Embedded derivatives in variable annuity contracts included in investment related gains 32,133 (6,205 ) 62,242 16,518 After the associated amortization of DAC and taxes, the related amounts included in net income 9,463 (1,074 ) 33,061 30,785 Amounts related to embedded derivatives in equity-indexed annuities included in benefits and expenses (25,347 ) (13,133 ) 6,523 (35,490 ) After the associated amortization of DAC and taxes, the related amounts included in net income (17,311 ) (9,737 ) (6,808 ) (38,059 )
Credit Risk	Information regarding the Company’s credit exposure related to its over-the-counter derivative contracts, centrally cleared derivative contracts and margin account for exchange-traded futures, excluding mortality swaps, at September 30, 2018 and December 31, 2017 are reflected in the following table (dollars in thousands): September 30, 2018 December 31, 2017 Estimated fair value of derivatives in net asset position $ 133,590 $ 155,714 Cash provided as collateral (1) 13,400 22,221 Securities pledged to counterparties as collateral (2) 61,293 58,156 Cash pledged from counterparties as collateral (3) (159,194 ) (185,900 ) Securities pledged from counterparties as collateral (4) — (862 ) Initial margin for cleared derivatives (2) (61,293 ) (58,156 ) Net amount after application of master netting agreements and collateral $ (12,204 ) $ (8,827 ) Margin account related to exchange-traded futures (5) $ 8,348 $ 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 Liab_2

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 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 September 30, 2018 and December 31, 2017 are summarized below (dollars in thousands): September 30, 2018: Fair Value Measurements Using: Total Level 1 Level 2 Level 3 Assets: Fixed maturity securities – available-for-sale: Corporate $ 24,449,498 $ — $ 23,193,563 $ 1,255,935 Canadian government 4,036,750 — 3,488,008 548,742 RMBS 1,780,762 — 1,780,762 — ABS 1,863,017 — 1,780,250 82,767 CMBS 1,273,534 — 1,271,752 1,782 U.S. government 1,412,409 1,284,932 107,225 20,252 State and political subdivisions 911,991 — 898,346 13,645 Other foreign government 3,277,251 — 3,272,239 5,012 Total fixed maturity securities – available-for-sale 39,005,212 1,284,932 35,792,145 1,928,135 Equity securities 101,069 57,584 — 43,485 Funds withheld at interest – embedded derivatives 142,529 — — 142,529 Cash equivalents 657,280 657,280 — — Short-term investments 186,051 5,957 177,891 2,203 Other invested assets: Derivatives: Interest rate swaps 29,106 — 29,106 — Foreign currency forwards 6,881 — 6,881 — CPI swaps (13 ) — (13 ) — Credit default swaps 5,961 — 5,961 — Equity options 16,818 — 16,818 — Foreign currency swaps 42,371 — 42,371 — FVO contractholder-directed unit-linked investments 212,315 211,253 1,062 — Total other invested assets 313,439 211,253 102,186 — Other assets - longevity swaps 46,090 — — 46,090 Total $ 40,451,670 $ 2,217,006 $ 36,072,222 $ 2,162,442 Liabilities: Interest sensitive contract liabilities – embedded derivatives $ 906,199 $ — $ — $ 906,199 Other liabilities: Derivatives: Interest rate swaps 14,166 — 14,166 — CPI swaps 2,696 — 2,696 — Credit default swaps (684 ) — (684 ) — Equity options (2,554 ) — (2,554 ) — Mortality swaps 308 — — 308 Total $ 920,131 $ — $ 13,624 $ 906,507 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 nine months ended September 30, 2017 (dollars in thousands): 2017 Transfers from Level 1 to Level 2 Transfers from Level 2 to Level 1 Three months ended September 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ — Nine months ended September 30: Fixed maturity securities - available-for-sale: Corporate securities $ — $ 88,674
Fair Value Inputs, Liabilities, Quantitative Information [Table Text Block]	The following table presents quantitative information about significant unobservable inputs used in Level 3 fair value measurements that are developed internally by the Company as of September 30, 2018 and December 31, 2017 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) September 30, 2018 December 31, 2017 September 30, 2018 December 31, 2017 Assets: Corporate $ 630,328 $ 173,579 Market comparable securities Liquidity premium 0-5% (1%) 0-2% (1%) EBITDA Multiple 5.9x-7.5x (6.9x) — ABS 64,475 — Market comparable securities Liquidity premium 0-1% (1%) — U.S. government 20,252 22,511 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions — 4,616 Market comparable securities Liquidity premium — 1 % Other foreign government 5,012 — Market comparable securities Liquidity premium 1 % — Equity securities 33,074 — Market comparable securities Liquidity premium 4 % — EBITDA Multiple 6.9x-12.3x (7.9x) — Discounted cash flow Discount rate 20 % Funds withheld at interest- embedded derivatives 142,529 122,194 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 46,090 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 815,970 861,758 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 90,229 152,470 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% (13%) 0-27% (8%) Mortality swaps 308 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 September 30, 2018 and December 31, 2017 (dollars in thousands): Estimated Fair Value Valuation Technique Unobservable Inputs Range (Weighted Average) September 30, 2018 December 31, 2017 September 30, 2018 December 31, 2017 Assets: Corporate $ 630,328 $ 173,579 Market comparable securities Liquidity premium 0-5% (1%) 0-2% (1%) EBITDA Multiple 5.9x-7.5x (6.9x) — ABS 64,475 — Market comparable securities Liquidity premium 0-1% (1%) — U.S. government 20,252 22,511 Market comparable securities Liquidity premium 0-1% (1%) 0-1% (1%) State and political subdivisions — 4,616 Market comparable securities Liquidity premium — 1 % Other foreign government 5,012 — Market comparable securities Liquidity premium 1 % — Equity securities 33,074 — Market comparable securities Liquidity premium 4 % — EBITDA Multiple 6.9x-12.3x (7.9x) — Discounted cash flow Discount rate 20 % Funds withheld at interest- embedded derivatives 142,529 122,194 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 46,090 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 815,970 861,758 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 90,229 152,470 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% (13%) 0-27% (8%) Mortality swaps 308 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 September 30, 2018: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,367,154 $ 572,698 $ 54,839 $ 70,686 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (156 ) 3,520 3 20 Investment related gains (losses), net 239 — — 626 Included in other comprehensive income (4,858 ) (27,476 ) (1 ) (130 ) Purchases (1) 123,808 — — 11,099 Sales (1) (62,047 ) — — (462 ) Settlements (1) (101,868 ) — (3 ) (24,166 ) Transfers into Level 3 2,782 — — 64,009 Transfers out of Level 3 (69,119 ) — (54,838 ) (38,915 ) Fair value, end of period $ 1,255,935 $ 548,742 $ — $ 82,767 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 $ (180 ) $ 3,520 $ — $ 13 Investment related gains (losses), net (1,430 ) — — — For the three months ended September 30, 2018 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 1,867 $ 20,735 $ 16,505 $ 5,044 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (107 ) 6 — Included in other comprehensive income 7 (122 ) (544 ) (32 ) Purchases (1) — 120 — — Settlements (1) (1 ) (374 ) (37 ) — Transfers into Level 3 1,752 — 9,859 — Transfers out of Level 3 (1,843 ) — (12,144 ) — Fair value, end of period $ 1,782 $ 20,252 $ 13,645 $ 5,012 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 $ — $ (107 ) $ 6 $ — For the three months ended September 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 $ 42,937 $ 144,610 $ 3,217 $ 43,971 $ (928,797 ) $ (782 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net 5,532 (2,081 ) — — 32,133 — Interest credited — — — — (25,348 ) — Included in other comprehensive income — — 47 (307 ) — 1 Other revenues — — — 2,426 — 473 Purchases (1) 863 — 1,721 — (4,231 ) — Sales (1) (5,847 ) — — — — — Settlements (1) — — — — 20,044 — Transfers out of Level 3 — — (2,782 ) — — — Fair value, end of period $ 43,485 $ 142,529 $ 2,203 $ 46,090 $ (906,199 ) $ (308 ) 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 $ 2,178 $ (2,081 ) $ — $ — $ 30,433 $ — Other revenues — — — 2,426 — 473 Interest credited — — — — (45,393 ) — For the nine months ended September 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 (822 ) 10,432 (132 ) 202 Investment related gains (losses), net (2,902 ) — 312 1,910 Included in other comprehensive income (35,532 ) (55,632 ) (1,782 ) (821 ) Purchases (1) 379,476 — 45,328 22,099 Sales (1) (79,316 ) — (4,961 ) (462 ) Settlements (1) (245,342 ) — (4,538 ) (46,449 ) Transfers into Level 3 9,948 — 3,031 68,977 Transfers out of Level 3 (106,847 ) — (145,140 ) (86,163 ) Fair value, end of period $ 1,255,935 $ 548,742 $ — $ 82,767 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 $ (845 ) $ 10,432 $ — $ 187 Investment related gains (losses), net (4,571 ) — — — For the nine months ended September 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 — (324 ) 4 — Included in other comprehensive income (56 ) (635 ) 46 (80 ) Purchases (1) — 334 — — Settlements (1) (4 ) (1,634 ) (158 ) — Transfers into Level 3 1,752 — 9,859 — Transfers out of Level 3 (3,144 ) — (37,309 ) — Fair value, end of period $ 1,782 $ 20,252 $ 13,645 $ 5,012 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 $ — $ (325 ) $ 3 $ — For the nine months ended September 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 (2,067 ) 20,335 — — 62,242 — Interest credited — — — — 6,523 — Included in other comprehensive income — — 1 (1,552 ) — 1 Other revenues — — — 6,983 — (326 ) Purchases (1) 13,111 — 2,202 — (16,946 ) — Sales (1) (6,416 ) — — — — — Settlements (1) (48 ) — (314 ) — 56,210 1,700 Transfers into Level 3 38,905 — — — — — Transfers out of Level 3 — — (2,782 ) — — — Fair value, end of period $ 43,485 $ 142,529 $ 2,203 $ 46,090 $ (906,199 ) $ (308 ) 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 $ (5,527 ) $ 20,335 $ — $ — $ 56,808 $ — Other revenues — — — 6,983 — (326 ) Interest credited — — — — (49,688 ) — For the three months ended September 30, 2017: Fixed maturity securities - available-for-sale Corporate Canadian government RMBS ABS Fair value, beginning of period $ 1,291,054 $ 533,270 $ 148,685 $ 201,589 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses (383 ) 3,460 (30 ) 160 Investment related gains (losses), net 396 — 44 — Included in other comprehensive income (2,700 ) (11,365 ) 104 (101 ) Purchases (1) 107,670 — 26,765 — Sales (1) (26,337 ) — (3,553 ) — Settlements (1) (88,551 ) — (3,645 ) (15,243 ) Transfers into Level 3 3,844 — 15 36,994 Transfers out of Level 3 (12,973 ) — (50,390 ) (78,202 ) Fair value, end of period $ 1,272,020 $ 525,365 $ 117,995 $ 145,197 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (394 ) $ 3,460 $ (27 ) $ 156 For the three months ended September 30, 2017 (continued): Fixed maturity securities available-for-sale CMBS U.S. government State Other foreign government Fair value, beginning of period $ 1,943 $ 23,567 $ 34,434 $ 11,994 Total gains/losses (realized/unrealized) Included in earnings, net: Investment income, net of related expenses — (116 ) 26 (1 ) Included in other comprehensive income 5 6 (208 ) (7 ) Purchases (1) — 134 — 495 Settlements (1) (1 ) (340 ) (35 ) — Transfers into Level 3 — — 7,295 — Transfers out of Level 3 — — — (6,853 ) Fair value, end of period $ 1,947 $ 23,251 $ 41,512 $ 5,628 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ — $ (116 ) $ 26 $ (1 ) For the three months ended September 30, 2017 (continued): Short-term Investments Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 3,548 $ 61,281 $ 33,349 $ (974,631 ) $ (1,552 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 23,044 — (10,047 ) — Interest credited — — — (8,335 ) — Included in other comprehensive income (3 ) — 1,144 — 1 Other revenues — — 3,334 — (132 ) Purchases (1) 3,164 — — (18,736 ) — Settlements (1) (114 ) — — 21,809 — Transfers out of Level 3 (3,236 ) — — — — Fair value, end of period $ 3,359 $ 84,325 $ 37,827 $ (989,940 ) $ (1,683 ) Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment related gains (losses), net $ — $ 23,044 $ — $ (11,900 ) $ — Other revenues — — 3,334 — (132 ) Interest credited — — — (30,145 ) — For the nine months ended September 30, 2017: Fixed maturity securities - available-for-sale Corporate 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 (1,202 ) 9,731 (304 ) 1,689 Investment related gains (losses), net 7,592 — 524 — Included in other comprehensive income (2,300 ) 39,669 2,716 6,802 Purchases (1) 257,671 — 72,582 45,215 Sales (1) (49,511 ) — (18,624 ) — Settlements (1) (234,552 ) — (15,084 ) (60,966 ) Transfers into Level 3 35,042 — 5,515 75,752 Transfers out of Level 3 (12,973 ) — (89,621 ) (142,575 ) Fair value, end of period $ 1,272,020 $ 525,365 $ 117,995 $ 145,197 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ (1,213 ) $ 9,731 $ (155 ) $ 556 Investment related gains (losses), net (2,788 ) — (346 ) — For the nine months ended September 30, 2017 (continued): Fixed maturity securities available-for-sale 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 (348 ) (68 ) (1 ) Investment related gains (losses), net (595 ) — — — Included in other comprehensive income (57 ) 269 (228 ) (210 ) Purchases (1) — 370 — 495 Sales (1) (3,720 ) — — — Settlements (1) (5,403 ) (1,528 ) (309 ) (672 ) Transfers into Level 3 — — 7,295 — Transfers out of Level 3 (10,132 ) — (6,844 ) (6,853 ) Fair value, end of period $ 1,947 $ 23,251 $ 41,512 $ 5,628 Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment income, net of related expenses $ — $ (348 ) $ (68 ) $ (1 ) For the nine months ended September 30, 2017 (continued): Short-term Investments Funds withheld at interest- embedded derivatives Other assets - longevity swaps Interest sensitive contract liabilities embedded derivatives Other liabilities - mortality swaps Fair value, beginning of period $ 3,346 $ (22,529 ) $ 26,958 $ (990,308 ) $ (2,462 ) Total gains/losses (realized/unrealized) Included in earnings, net: Investment related gains (losses), net — 106,854 — 9,005 — Interest credited — — — (20,408 ) — Included in other comprehensive income 1 — 3,689 — 1 Other revenues — — 7,180 — (922 ) Purchases (1) 3,520 — — (51,276 ) — Settlements (1) (272 ) — — 63,047 1,700 Transfers out of Level 3 (3,236 ) — — — — Fair value, end of period $ 3,359 $ 84,325 $ 37,827 $ (989,940 ) $ (1,683 ) Unrealized gains and losses recorded in earnings for the period relating to those Level 3 assets and liabilities that were still held at the end of the period Included in earnings, net: Investment related gains (losses), net $ — $ 106,854 $ — $ 2,934 $ — Other revenues — — 7,180 — (922 ) Interest credited — — — (83,456 ) — (1) The amount reported within purchases, sales and settlements is the purchase price (for purchases) and the sales/settlement proceeds (for sales and settlements) based upon the actual date purchased or sold/settled. Items purchased and sold/settled in the same period are excluded from the rollforward. The Company had no issuances during the period.
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Table Text Block]	Carrying Value After Measurement Net Investment Gains (Losses) At September 30, Three months ended September 30, Nine months ended September 30, (dollars in thousands) 2018 2017 2018 2017 2018 2017 Limited partnership interests (1) $ 2,246 $ 4,656 $ (1,860 ) $ (896 ) $ (1,860 ) $ (7,204 ) Private equities (2) — 106 — (531 ) — (531 ) (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 September 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. September 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 $ 4,779,074 $ 4,652,481 $ — $ — $ 4,652,481 $ — Policy loans 1,320,050 1,320,050 — 1,320,050 — — Funds withheld at interest 5,833,925 6,040,671 — — 6,040,671 — Cash and cash equivalents 1,073,209 1,073,209 1,073,209 — — — Short-term investments 43,877 43,877 43,877 — — — Other invested assets 842,626 839,280 5,618 71,401 382,284 379,977 Accrued investment income 455,296 455,296 — 455,296 — — Liabilities: Interest-sensitive contract liabilities $ 13,319,348 $ 13,113,427 $ — $ — $ 13,113,427 $ — Long-term debt 2,787,975 2,850,344 — — 2,850,344 — Collateral finance and securitization notes 710,792 652,380 — — 652,380 — 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)	9 Months Ended
	Sep. 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 September 30, Nine months ended September 30, Revenues: 2018 2017 2018 2017 U.S. and Latin America: Traditional $ 1,547,790 $ 1,521,383 $ 4,601,631 $ 4,532,584 Financial Solutions 290,848 264,170 734,148 834,992 Total 1,838,638 1,785,553 5,335,779 5,367,576 Canada: Traditional 295,962 281,095 910,480 814,643 Financial Solutions 12,168 12,430 37,034 36,240 Total 308,130 293,525 947,514 850,883 Europe, Middle East and Africa: Traditional 357,059 360,972 1,123,379 1,024,978 Financial Solutions 91,664 77,041 280,482 230,435 Total 448,723 438,013 1,403,861 1,255,413 Asia Pacific: Traditional 578,035 561,660 1,763,094 1,628,419 Financial Solutions 16,167 16,932 54,005 55,368 Total 594,202 578,592 1,817,099 1,683,787 Corporate and Other 37,838 49,627 92,893 125,667 Total $ 3,227,531 $ 3,145,310 $ 9,597,146 $ 9,283,326
Reconciliation Of Operating Profit Loss From Segments To Consolidated Text Block	Three months ended September 30, Nine months ended September 30, Income (loss) before income taxes: 2018 2017 2018 2017 U.S. and Latin America: Traditional $ 116,328 $ 160,512 $ 191,198 $ 281,066 Financial Solutions 87,073 89,118 236,882 299,689 Total 203,401 249,630 428,080 580,755 Canada: Traditional 21,149 28,789 66,661 80,953 Financial Solutions 1,646 4,472 8,381 12,489 Total 22,795 33,261 75,042 93,442 Europe, Middle East and Africa: Traditional 18,370 15,421 40,259 40,751 Financial Solutions 56,205 30,953 160,738 91,776 Total 74,575 46,374 200,997 132,527 Asia Pacific: Traditional 62,007 26,564 143,756 121,574 Financial Solutions 206 (229 ) 8,365 11,020 Total 62,213 26,335 152,121 132,594 Corporate and Other (40,323 ) (15,438 ) (148,366 ) (51,997 ) Total $ 322,661 $ 340,162 $ 707,874 $ 887,321
Reconciliation Of Assets From Segment To Consolidated Text Block	Assets: September 30, 2018 December 31, 2017 U.S. and Latin America: Traditional $ 19,148,790 $ 18,603,423 Financial Solutions 19,251,832 15,959,206 Total 38,400,622 34,562,629 Canada: Traditional 4,210,051 4,161,452 Financial Solutions 146,374 126,372 Total 4,356,425 4,287,824 Europe, Middle East and Africa: Traditional 3,573,449 3,099,495 Financial Solutions 4,585,297 5,274,993 Total 8,158,746 8,374,488 Asia Pacific: Traditional 5,312,822 4,915,442 Financial Solutions 1,181,954 1,198,585 Total 6,494,776 6,114,027 Corporate and Other 5,562,073 7,175,850 Total $ 62,972,642 $ 60,514,818

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Tables)	9 Months Ended
	Sep. 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 September 30, 2018 and December 31, 2017 are presented in the following table (dollars in thousands): September 30, 2018 December 31, 2017 Limited partnership interests and joint ventures $ 578,944 $ 485,197 Commercial mortgage loans 120,571 40,815 Bank loans and private placements 101,992 60,472 Equity release mortgages 213,459 153,937
Other Commitments [Table Text Block]	The following table presents the maximum potential obligation for these commitments as of September 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 September 30, 2018 and December 31, 2017 are reflected in the following table (dollars in thousands): September 30, 2018 December 31, 2017 Treaty guarantees $ 1,073,184 $ 1,047,449 Treaty guarantees, net of assets in trust 966,099 926,393 Securities borrowing and repurchase arrangements 276,190 294,325 Financing arrangements 69,221 86,183 Lease obligations 881 1,662

Income Tax (Tables)

Income Tax (Tables)	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	three and nine months ended September 30, 2018 and 2017 , respectively (dollars in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Tax provision at U.S. statutory rate $ 67,759 $ 119,057 $ 148,654 $ 310,562 Increase (decrease) in income taxes resulting from: U.S. Tax Reform provisional adjustments 664 — (2,685 ) — U.S. Tax Reform valuation allowance adjustments (58,949 ) — (59,139 ) — Foreign tax rate differing from U.S. tax rate 7,537 (3,635 ) 8,795 (14,049 ) Differences in tax bases in foreign jurisdictions (2,371 ) 2,126 (9,264 ) (14,633 ) Deferred tax valuation allowance (5,334 ) (2,501 ) 5,357 11,627 Amounts related to tax audit contingencies 1,851 299 650 (873 ) Corporate rate changes (166 ) (1,139 ) 30 (2,332 ) Subpart F (99 ) 64 211 1,390 Foreign tax credits (544 ) 1,230 (1,003 ) (834 ) Global intangible low-taxed income, net of credit 7,624 — 11,916 — Equity compensation excess benefit (817 ) (2,762 ) (5,067 ) (7,226 ) Return to provision adjustments 4,213 452 4,108 133 Other, net 94 (620 ) (492 ) (1,737 ) Total provision for income taxes $ 21,462 $ 112,571 $ 102,071 $ 282,028 Effective tax rate 6.7 % 33.1 % 14.4 % 31.8 %

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 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 nine months ended September 30, 2018 and 2017 were as follows (dollars in thousands): Pension Benefits Other Benefits Three months ended September 30, Three months ended September 30, 2018 2017 2018 2017 Service cost $ 3,106 $ 2,699 $ 999 $ 465 Interest cost 1,341 1,314 680 459 Expected return on plan assets (1,884 ) (1,554 ) — — Amortization of prior service cost (credit) 82 85 (328 ) (675 ) Amortization of prior actuarial losses 929 1,081 937 580 Settlements — 256 — — Net periodic benefit cost $ 3,574 $ 3,881 $ 2,288 $ 829 Pension Benefits Other Benefits Nine months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Service cost $ 9,330 $ 8,098 $ 2,271 $ 1,907 Interest cost 4,028 3,943 1,739 1,589 Expected return on plan assets (5,651 ) (4,662 ) — — Amortization of prior service cost (credit) 247 254 (986 ) (986 ) Amortization of prior actuarial losses 2,792 3,244 1,933 1,494 Settlements — 769 — — Net periodic benefit cost $ 10,746 $ 11,646 $ 4,957 $ 4,004

Reinsurance (Tables)

Reinsurance (Tables)	9 Months Ended
	Sep. 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 September 30, 2018 or December 31, 2017 (dollars in thousands): September 30, 2018 December 31, 2017 Reinsurer A.M. Best Rating Amount % of Total Amount % of Total Reinsurer A A+ $ 303,942 39.5 $ 301,478 38.6 % Reinsurer B A+ 203,702 26.5 203,898 26.1 Reinsurer C A 67,599 8.8 67,723 8.7 Reinsurer D A+ 41,049 5.3 40,528 5.2 Reinsurer E A++ 35,090 4.6 40,592 5.2 Other reinsurers 117,942 15.3 127,808 16.2 Total $ 769,324 100.0 % $ 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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Net income (numerator for basic and diluted calculations)	$ 301,199	$ 227,591	$ 605,803	$ 605,293
Shares:
Weighted average outstanding shares (denominator for basic calculation)	63,279	64,488	63,941	64,430
Equivalent shares from outstanding stock options	1,017	1,165	1,189	1,174
Denominator for diluted calculation	64,296	65,653	65,130	65,604
Earnings Per Share:
Basic earnings per share	$ 4.76	$ 3.53	$ 9.47	$ 9.39
Diluted earnings per share	$ 4.68	$ 3.47	$ 9.30	$ 9.23

Earnings Per Share (Stock Optio

Earnings Per Share (Stock Options and Performance Shares Excluded From Common Equivalent Shares) (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 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	227	87	349	296
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	276	307	256	293

Equity (Common Stock Changes In

Equity (Common Stock Changes In Number of Shares Issued, Held In Treasury and Outstanding) (Details) - shares		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common Stock, Shares, Issued		79,137,758		79,137,758		79,137,758
Treasury Stock, Shares, Acquired				1,800,000	200,000
Common Stock Issuable [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		79,137,758	79,137,758	79,137,758	79,137,758	79,137,758	79,137,758
Treasury Stock, Shares, Acquired		0	0
Stock Based Compensation Shares	[1]	0	0
Common Stock Held In Treasury [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		16,186,890	14,769,487	16,186,890	14,769,487	14,685,663	14,835,256
Treasury Stock, Shares, Acquired		1,750,295	208,680
Stock Based Compensation Shares	[1]	(249,068)	(274,449)
Common Stock Outstanding [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		62,950,868	64,368,271	62,950,868	64,368,271	64,452,095	64,302,502
Treasury Stock, Shares, Acquired		(1,750,295)	(208,680)
Stock Based Compensation Shares	[1]	(249,068)	(274,449)
[1]	Represents net shares issued from treasury pursuant to the Company’s equity-based compensation programs.

Equity (Balance of and Changes

Equity (Balance of and Changes in Each Component of AOCI) (Details) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Accumulated other comprehensive income		$ 812,805	$ 1,625,757	$ 2,063,631	$ 1,139,329
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(1,666,514)	694,490
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		83,491	(47,401)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		2,573		156,400
Other Comprehensive Income (Loss), Tax		334,770	(160,661)
Accumulated Translation Adjustment [Member]
Accumulated other comprehensive income		(119,298)	(104,456)	(86,350)	(172,541)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(24,977)	23,117
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		0	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(2,573)
Other Comprehensive Income (Loss), Tax		5,398	(44,968)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated other comprehensive income	[1]	982,352	1,770,903	2,200,661	1,355,033
Other Comprehensive Income (Loss), before Reclassifications, before Tax	[1]	(1,638,146)	671,564
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	[1]	79,505	(51,407)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	[1]	0
Other Comprehensive Income (Loss), Tax	[1]	340,332	(204,287)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated other comprehensive income		(50,249)	(40,690)	$ (50,680)	$ (43,163)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(3,391)	(191)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		3,986	4,006
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		0
Other Comprehensive Income (Loss), Tax		$ (164)	$ (1,342)
[1]	Includes cash flow hedges of $29,043 and $2,619 as of September 30, 2018 and December 31, 2017, respectively, and $347 and $(2,496) as of September 30, 2017 and December 31, 2016, respectively. See Note 5 - “Derivative Instruments” for additional information on cash flow hedges.

Equity (Balance of and Change_2

Equity (Balance of and Changes in Each Component of AOCI) (Footnote) (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2018	Sep. 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	$ 29,043	$ 347	$ 22,656	$ 7,690	$ 29,043	$ 347	$ 2,619	$ (2,496)

Equity (Schedule of Reclassific

Equity (Schedule of Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		$ (9,312)		$ 23,043		$ (17,004)		$ 160,451
Investment income		572,742		556,918		1,617,132		1,589,820
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		322,661		340,162		707,874		887,321
Income Tax Expense (Benefit)		(21,462)		(112,571)		(102,071)		(282,028)
Net income		301,199		227,591		605,803		605,293
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		(25,858)		12,085		(79,505)		51,407
Income Tax Expense (Benefit)		5,355		(3,991)		16,978		(16,015)
Net income		(20,503)		8,094		(62,527)		35,392
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		(21,249)		10,515		(60,347)		39,032
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]	234		0		(108)		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]	50		230		270		560
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		224		0		286
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		(4,893)	[1]	1,116	[1]	19,320	[2]	11,529	[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		(1,620)		(1,071)		(3,986)		(4,006)
Income Tax Expense (Benefit)		340		375		837		1,402
Net income		(1,280)		(696)		(3,149)		(2,604)
Amounts Reclassified From AOCI [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		(21,783)		7,398		(65,676)		32,788
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		246	[2]	590	[2]	739	[3]	732	[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)		$ (1,866)	[2]	$ (1,661)	[2]	$ 4,725	[3]	$ (4,738)	[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) - USD ($) shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Stock Repurchase Program, Authorized Amount	$ 400
Treasury Stock, Shares, Acquired	1.8	0.2
Treasury Stock, Value, Acquired, Cost Method	$ 258.5	$ 26.9

Equity Based Compensation (Narr

Equity Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity compensation expense	$ 28.4	$ 17.1
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)	$ 66.48
Options, remaining term	4 years 3 months
Compensation cost not yet recognized	$ 35.1
Period for recognition	1 year 3 months

Investments (Investments in Fix

Investments (Investments in Fixed Maturity and Equity Securities Available-for-Sale by Sector) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 24,271,467	$ 21,966,803
Estimated Fair Value	$ 24,449,498	$ 23,210,968
% of Total	100.00%	100.00%
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 37,751,132	$ 35,281,412
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,907,163	2,982,754
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	653,083	113,346
Estimated Fair Value	$ 39,005,212	$ 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	24,271,467	$ 21,966,803
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	594,444	1,299,594
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	416,413	55,429
Estimated Fair Value	$ 24,449,498	$ 23,210,968
% of Total	62.70%	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	2,902,433	2,843,273
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,138,426	1,378,510
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	4,109	1,707
Estimated Fair Value	$ 4,036,750	$ 4,220,076
% of Total	10.30%	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	1,816,949	1,695,126
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	14,235	36,632
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	50,422	11,878
Estimated Fair Value	$ 1,780,762	$ 1,719,880
% of Total	4.60%	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	1,867,650	1,634,758
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	10,312	18,798
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	14,945	5,194
Estimated Fair Value	$ 1,863,017	$ 1,648,362
% of Total	4.80%	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	1,282,015	1,285,594
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	8,403	22,627
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	16,884	4,834
Estimated Fair Value	$ 1,273,534	$ 1,303,387
% of Total	3.30%	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	1,500,703	1,953,436
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	6,359	12,089
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	94,653	21,933
Estimated Fair Value	$ 1,412,409	$ 1,943,592
% of Total	3.60%	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	889,218	647,727
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	36,410	59,997
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	13,637	4,296
Estimated Fair Value	$ 911,991	$ 703,428
% of Total	2.30%	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	3,220,697	3,254,695
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	98,574	154,507
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	42,020	8,075
Estimated Fair Value	$ 3,277,251	$ 3,401,127
% of Total	8.40%	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	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 24,271,467	$ 21,966,803
Available-for-sale Securities	24,449,498	23,210,968
Collateral Fixed Maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	67,899	72,542
Available-for-sale Securities	69,792	75,622
Collateral Received Fixed Maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities	592,146	590,417
Reported Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held-in-trust	19,263,724	15,584,296
Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held-in-trust	$ 19,670,559	$ 16,715,281

Investments (Exposure To Concen

Investments (Exposure To Concentrations Of Credit Risk) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 24,271,467	$ 21,966,803
Available-for-sale Securities	24,449,498	23,210,968
Canadian Province Of Quebec Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	951,186	939,837
Available-for-sale Securities	1,225,712	1,282,944
Canadian Province Of Ontario Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,158,326	1,119,337
Available-for-sale Securities	$ 1,833,972	$ 1,917,996

Investments (Amortized Cost and

Investments (Amortized Cost and Fair Value of Fixed Maturities by Contractual Maturities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Available For Sale Securities Debt Maturities Amortized Cost
Due in one year or less	$ 986,289
Due after one year through five years	7,797,732
Due after five year through ten years	9,311,737
Due after ten years	14,688,760
Asset and mortgage-backed securities	4,966,614
Total	37,751,132	$ 35,281,412
Available For Sale Securities Debt Maturities Fair Value
Due in one year or less	993,352
Due after one year through five years	7,888,116
Due after five year through ten years	9,407,186
Due after ten years	15,799,245
Asset and mortgage-backed securities	4,917,313
Total	$ 39,005,212	$ 38,150,820

Investments (Amortized Cost a_2

Investments (Amortized Cost and Fair Value of Fixed Maturity Holdings by Industry Type) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 24,271,467	$ 21,966,803
Estimated Fair Value	$ 24,449,498	$ 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	$ 8,561,885	$ 7,977,885
Estimated Fair Value	$ 8,564,254	$ 8,362,774
% of Total	35.10%	36.10%
Commercial and Industrial Sector [Member]
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 12,632,502	$ 11,535,166
Estimated Fair Value	$ 12,753,024	$ 12,199,333
% of Total	52.10%	52.50%
Utility Sector [Member]
Corporate Securities by Investment Sector And Credit Rating [Line Items]
Amortized Cost	$ 3,077,080	$ 2,453,752
Estimated Fair Value	$ 3,132,220	$ 2,648,861
% of Total	12.80%	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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 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	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 653,083	$ 116,993
% of Total	100.00%	100.00%
Less than 20%
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 640,481	$ 113,466
% of Total	98.10%	97.00%
20% or more for less than six months
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 309	$ 689
% of Total	0.00%	0.60%
20% or more for six months or greater
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 12,293	$ 2,838
% of Total	1.90%	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	Sep. 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	$ 14,519,974	$ 4,565,273
Gross Unrealized Losses - Less than 12 months	410,779	40,239
Estimated Fair Value - 12 months or greater	3,874,370	2,738,393
Gross Unrealized Losses - 12 months or greater	242,304	73,107
Estimated Fair Value	18,394,344	7,303,666
Gross Unrealized Losses	653,083	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	682,541	225,474
Gross Unrealized Losses - Less than 12 months	30,048	3,450
Estimated Fair Value - 12 months or greater	86,297	93,723
Gross Unrealized Losses - 12 months or greater	7,729	7,559
Estimated Fair Value	768,838	319,197
Gross Unrealized Losses	37,777	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	13,837,433	4,339,799
Gross Unrealized Losses - Less than 12 months	380,731	36,789
Estimated Fair Value - 12 months or greater	3,788,073	2,644,670
Gross Unrealized Losses - 12 months or greater	234,575	65,548
Estimated Fair Value	17,625,506	6,984,469
Gross Unrealized Losses	615,306	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	539,521	194,879
Gross Unrealized Losses - Less than 12 months	23,955	3,317
Estimated Fair Value - 12 months or greater	77,675	75,731
Gross Unrealized Losses - 12 months or greater	7,296	6,933
Estimated Fair Value	617,196	270,610
Gross Unrealized Losses	31,251	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	10,117,970	1,886,212
Gross Unrealized Losses - Less than 12 months	303,926	17,099
Estimated Fair Value - 12 months or greater	1,290,804	1,009,750
Gross Unrealized Losses - 12 months or greater	81,236	28,080
Estimated Fair Value	11,408,774	2,895,962
Gross Unrealized Losses	385,162	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	2,328	1,995
Gross Unrealized Losses - Less than 12 months	162	20
Estimated Fair Value - 12 months or greater	0	0
Gross Unrealized Losses - 12 months or greater	0	0
Estimated Fair Value	2,328	1,995
Gross Unrealized Losses	162	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	58,816	18,688
Gross Unrealized Losses - Less than 12 months	1,211	91
Estimated Fair Value - 12 months or greater	107,167	111,560
Gross Unrealized Losses - 12 months or greater	2,736	1,596
Estimated Fair Value	165,983	130,248
Gross Unrealized Losses	3,947	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	1,102	1,369
Gross Unrealized Losses - 12 months or greater	20	22
Estimated Fair Value	1,102	1,369
Gross Unrealized Losses	20	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	931,044	566,699
Gross Unrealized Losses - Less than 12 months	23,339	5,852
Estimated Fair Value - 12 months or greater	528,739	224,439
Gross Unrealized Losses - 12 months or greater	27,063	6,004
Estimated Fair Value	1,459,783	791,138
Gross Unrealized Losses	50,402	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	1,110	1,489
Gross Unrealized Losses - 12 months or greater	52	53
Estimated Fair Value	1,110	1,489
Gross Unrealized Losses	52	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	680,900	434,274
Gross Unrealized Losses - Less than 12 months	8,650	2,707
Estimated Fair Value - 12 months or greater	262,544	168,524
Gross Unrealized Losses - 12 months or greater	6,243	2,434
Estimated Fair Value	943,444	602,798
Gross Unrealized Losses	14,893	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	555,716	220,401
Gross Unrealized Losses - Less than 12 months	8,304	1,914
Estimated Fair Value - 12 months or greater	207,943	103,269
Gross Unrealized Losses - 12 months or greater	8,580	2,920
Estimated Fair Value	763,659	323,670
Gross Unrealized Losses	16,884	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	197,114	800,298
Gross Unrealized Losses - Less than 12 months	3,913	6,177
Estimated Fair Value - 12 months or greater	1,002,661	767,197
Gross Unrealized Losses - 12 months or greater	90,740	15,756
Estimated Fair Value	1,199,775	1,567,495
Gross Unrealized Losses	94,653	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	261,456	43,510
Gross Unrealized Losses - Less than 12 months	6,722	242
Estimated Fair Value - 12 months or greater	90,649	68,666
Gross Unrealized Losses - 12 months or greater	6,915	4,054
Estimated Fair Value	352,105	112,176
Gross Unrealized Losses	13,637	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	140,692	28,600
Gross Unrealized Losses - Less than 12 months	5,931	113
Estimated Fair Value - 12 months or greater	6,410	15,134
Gross Unrealized Losses - 12 months or greater	361	551
Estimated Fair Value	147,102	43,734
Gross Unrealized Losses	6,292	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	1,034,417	369,717
Gross Unrealized Losses - Less than 12 months	24,666	2,707
Estimated Fair Value - 12 months or greater	297,566	191,265
Gross Unrealized Losses - 12 months or greater	11,062	4,704
Estimated Fair Value	1,331,983	560,982
Gross Unrealized Losses	$ 35,728	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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	$ 596,035	$ 576,317	$ 1,684,151	$ 1,646,934
Investment expense	(23,293)	(19,399)	(67,019)	(57,114)
Investment income, net of related expenses	572,742	556,918	1,617,132	1,589,820
Available-for-sale Securities [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	378,669	359,157	1,121,496	1,039,392
Equity securities
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	1,319	942	3,710	3,296
Mortgage Loans on Real Estate [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	54,424	50,040	155,083	138,829
Policy loans
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	14,730	15,404	44,285	45,870
Funds withheld at interest
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	108,232	102,144	270,094	327,089
Short-term Investments [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	3,067	1,977	9,276	5,266
Other invested assets
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment revenue	$ 35,594	$ 46,653	$ 80,207	$ 87,192

Investments (Investment Related

Investments (Investment Related Gains (Losses) Net) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Investments [Abstract]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	$ 10,705	$ 390	$ 14,055	$ 20,980
Investment Gains And Losses [Abstract]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0	889	0	889
Gain on investment activity	(20,040)	(19,512)	(52,146)	(91,611)
Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments	(37,880)	(7,593)	(94,194)	(26,577)
Available-for-sale Equity Securities, Gross Unrealized Gain	3,932	10	4,429	24
Available-for-sale Equity Securities, Gross Unrealized Loss	(174)	(85)	(1,124)	(4,135)
Gain (Loss) on Sale of Equity Investments	3,539	0	(7,564)	0
Other impairment losses and change in mortgage loan provision	(6,566)	(2,446)	(8,235)	(9,220)
Derivatives and other, net	7,797	14,534	37,538	109,637
Total investment related gains (losses), net	$ (20,017)	$ 22,653	$ (31,059)	$ 139,471

Investments (Borrowed Securitie

Investments (Borrowed Securities Repurchased Securities And Repurchased Reversed Repurchased Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Securities Loaned, Fair Value of Collateral	$ 102,489	$ 121,551
Securities Received as Collateral	112,000	128,000
Securities for Reverse Repurchase Agreements	408,679	413,819
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	400,515	417,550
Reported Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Securities Borrowed	353,650	358,875
Securities Loaned, Fair Value of Collateral	101,965	117,246
Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Securities Borrowed	370,323	377,820
Securities for Reverse Repurchase Agreements	$ 404,905	$ 428,344

Investments (Securities Pledged

Investments (Securities Pledged as Collateral Related to Repurchase Reverse Repurchase Program) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	$ 102,489	$ 121,551
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	404,905	428,344
Obligation to Return Securities Received as Collateral	507,394	549,895
Securities Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	541,411	576,786
SecuredBorrowingsGrossDifferenceAmount	34,017	26,891
Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	1,131
Obligation to Return Securities Received as Collateral	0	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	404,905	426,901
Obligation to Return Securities Received as Collateral	507,394	548,452
Corporate Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Fair Value of Collateral	102,489	121,551
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	132,228	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	102,489	121,551
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	132,228	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	219,906
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	219,906
Debt Security, Government, Non-US [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	52,771	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	52,771	21,802
Other Debt Obligations [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	1,131
Other Debt Obligations [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
FinancialAssetsSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement	0	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	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 4,794,226		$ 4,413,171
Percentage of total	100.00%		100.00%
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ (4,786)		$ (3,254)
Allowance for Loan and Lease Losses, Real Estate	(10,366)	$ (9,706)	(9,384)	$ (9,137)	$ (8,156)	$ (7,685)
Mortgage loans on real estate (net of allowances of $10,366 and $9,384)	4,779,074		4,400,533
Apartment
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 543,917		$ 510,052
Percentage of total	11.30%		11.60%
Retail
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 1,365,157		$ 1,270,676
Percentage of total	28.50%		28.80%
Office building
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 1,633,887		$ 1,487,392
Percentage of total	34.10%		33.60%
Industrial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 983,553		$ 938,612
Percentage of total	20.50%		21.30%
Other commercial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Recorded investment	$ 267,712		$ 206,439
Percentage of total	5.60%		4.70%

Investments (Mortgage Loans b_2

Investments (Mortgage Loans by Maturity Date) (Details) - USD ($) $ in Thousands	Sep. 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	$ 4,794,226	$ 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	$ 1,216,241	$ 1,091,066
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	25.40%	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	$ 2,738,400	$ 2,516,872
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	57.10%	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	$ 839,585	$ 805,233
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	17.50%	18.20%

Investments (Mortgage Loans b_3

Investments (Mortgage Loans by Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 4,794,226	$ 4,413,171
Loans Receivable, Gross, Commercial, Construction	$ 25,724	$ 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	$ 2,279,405	$ 2,206,208
Loans Receivable, Gross, Commercial, Construction	$ 25,724	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	47.60%	50.00%
LTV 60 To 69 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 1,846,868	$ 1,608,078
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	38.50%	36.40%
LTV 70 To 79 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 533,075	$ 431,274
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	11.10%	9.80%
LTV 80 to 100 Percent [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 134,878	$ 167,611
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 9,686
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	2.80%	3.80%
Debt Service Coverage Ratio Range One [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 4,307,296	$ 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	2,146,401	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	1,666,525	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	386,137	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	108,233	120,850
Debt Service Coverage Ratio Range Two [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	274,833	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	63,794	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	117,726	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	70,884	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	22,429	30,713
Debt Service Coverage Ratio Range Three [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	186,373	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	43,486	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	62,617	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	76,054	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	$ 4,216	$ 6,362

Investments (Age Analysis of Pa

Investments (Age Analysis of Past Due Recorded Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 0	$ 19,156
Financing Receivable, Recorded Investment, Current	4,794,226	4,394,015
Loans Receivable, Gross, Commercial, Real Estate	4,794,226	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	0	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 b_4

Investments (Mortgage Loans by Method of Evaluation and Related Valuation Allowances) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Mortgage Loans:
Total mortgage loans	$ 4,794,226	$ 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)	4,779,074	4,400,533
Commercial Real Estate Portfolio Segment [Member]
Mortgage Loans:
Evaluated individually for credit losses	30,629	5,858
Evaluated collectively for credit losses	4,763,597	4,407,313
Total mortgage loans	4,794,226	4,413,171
Valuation Allowances:
Specific for credit losses	0	0
Non-specifically identified credit losses	10,366	9,384
Total valuation allowances	$ 10,366	$ 9,384

Investments (Loan Valuation All

Investments (Loan Valuation Allowance for Mortgage Loans) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allowance For Loan And Lease Losses Roll Forward
Balance, Beginning of Period	$ 9,706	$ 8,156	$ 9,384	$ 7,685
Provision (release)	656	977	986	1,444
Allowance for Loan and Lease Losses, Foreign Currency Translation	4	4	(4)	8
Balance, End of Period	$ 10,366	$ 9,137	$ 10,366	$ 9,137

Investments (Impaired Mortgage

Investments (Impaired Mortgage Loans) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		$ 30,660		$ 30,660		$ 6,427
Recorded Investment		30,629		30,629		5,858
Related Allowance		0		0		0
Carrying Value		30,629		30,629		5,858
Average Investment	[1]	30,641	$ 3,967	22,641	$ 3,062
Interest Income		346	33	650	100
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		30,660		30,660		6,427
Recorded Investment		30,629		30,629		5,858
Related Allowance		0		0		0
Carrying Value		30,629		30,629		$ 5,858
Average Investment	[1]	30,641	3,967	22,641	3,062
Interest Income		$ 346	$ 33	$ 650	$ 100
[1]	Average recorded investment represents the average loan balances as of the beginning of period and all subsequent quarterly end of period balances.

Investments (Other Invested Ass

Investments (Other Invested Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Other invested assets	$ 1,706,979	$ 1,505,332
Equity Release Mortgages [Member]
Other invested assets	383,450	219,940
Limited Partner [Member]
Other invested assets	924,006	781,124
Derivatives
Other invested assets	101,124	137,613
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Other invested assets	212,315	218,541
Other
Other invested assets	$ 86,084	$ 148,114

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)securities	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)securities	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)securities
Investment Narrative [Line Items]
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash	$ 28,900		$ 28,900		$ 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	1,345,300	$ 479,700	3,783,300	$ 1,604,700
Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments	$ 37,880	7,593	$ 94,194	26,577
Policy Loans Percent Of Total Investments	2.50%		2.50%		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	2,866		2,866		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	11.30%		11.30%		11.80%
Funds withheld at interest	$ 5,976,301		$ 5,976,301		$ 6,083,388
Funds Held Under Reinsurance Agreements Asset Specific Client	$ 3,900,000		$ 3,900,000
Other Invested Assets Percent Of Cash And Invested Assets	3.20%		3.20%		2.90%
ProceedsFromSaleOfAvailableForSaleEquitySecuritiesSoldAtLoss	$ 3,100	5,000	$ 31,500	166,700
Available-for-sale Equity Securities, Gross Unrealized Loss	$ 174	$ 85	$ 1,124	$ 4,135
CALIFORNIA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	18.80%		18.80%
TEXAS
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	10.00%		10.00%
GEORGIA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	7.50%		7.50%
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	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount	$ 17,380,622	$ 15,904,127
Carrying Value / Fair Value of Assets	307,303	320,724
Derivative Liability, Fair Value, Gross Liability	937,691	1,058,727
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	15,574,135	14,243,031
Carrying Value / Fair Value of Assets	252,115	254,252
Derivative Liability, Fair Value, Gross Liability	911,275	1,022,122
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	1,074,173	996,204
Carrying Value / Fair Value of Assets	37,238	59,809
Derivative Liability, Fair Value, Gross Liability	1,818	2,372
Not Designated as Hedging Instrument | Financial Futures
Derivative [Line Items]
Notional Amount	347,916	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	0	6,030
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	0	28
Not Designated as Hedging Instrument | Consumer Price Index Swap [Member]
Derivative [Line Items]
Notional Amount	409,023	221,932
Carrying Value / Fair Value of Assets	127	0
Derivative Liability, Fair Value, Gross Liability	2,836	2,160
Not Designated as Hedging Instrument | Credit Default Swaps
Derivative [Line Items]
Notional Amount	1,373,300	961,200
Carrying Value / Fair Value of Assets	6,759	8,319
Derivative Liability, Fair Value, Gross Liability	114	1,651
Not Designated as Hedging Instrument | Equity Options
Derivative [Line Items]
Notional Amount	571,845	632,251
Carrying Value / Fair Value of Assets	19,372	23,271
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument | Longevity Swap [Member]
Derivative [Line Items]
Notional Amount	928,320	960,400
Carrying Value / Fair Value of Assets	46,090	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	308	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	142,529	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	815,970	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	90,229	152,470
Not Designated as Hedging Instrument | Synthetic Guaranteed Investment Contracts
Derivative [Line Items]
Notional Amount	10,844,558	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	1,806,487	1,661,096
Carrying Value / Fair Value of Assets	55,188	66,472
Derivative Liability, Fair Value, Gross Liability	26,416	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	99	0
Derivative Liability, Fair Value, Gross Liability	20,579	20,389
Designated As Hedging Instrument | Foreign Currency Forwards
Derivative [Line Items]
Notional Amount	834,238	553,175
Carrying Value / Fair Value of Assets	8,948	1,265
Derivative Liability, Fair Value, Gross Liability	2,067	7,720
Designated As Hedging Instrument | Currency Swap [Member]
Derivative [Line Items]
Notional Amount	537,249	672,921
Carrying Value / Fair Value of Assets	46,141	65,207
Derivative Liability, Fair Value, Gross Liability	$ 3,770	$ 8,496

Derivative Instruments (Derivat

Derivative Instruments (Derivative Instruments Offsetting Balance Sheet) (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Derivative Assets [Abstract]
Derivative Fair Value Of Free Standing Derivative Asset		$ 164,774	$ 198,530
Gross Amounts Offset in the Balance Sheet		(17,560)	(20,258)
Net Amounts Presented in the Balance Sheet		147,214	178,272
Derivative Asset, Fair Value of Collateral	[1]	0	(862)
Gross Amounts Not Offset in the Balance Sheet - Cash Collateral Pledged/Received	[2]	(159,194)	(185,900)
Net Amount		(11,980)	(8,490)
Derivative Liabilities [Abstract]
Derivative Fair Value Of Free Standing Derivative Liability		31,492	44,499
Gross Amounts Offset in the Balance Sheet		(17,560)	(20,258)
Net Amounts Presented in the Balance Sheet		13,932	24,241
Gross Amounts Not Offset in the Balance Sheet - Financial Instruments	[3]	(61,293)	(58,156)
Gross Amounts Not Offset in the Balance Sheet - Cash Collateral Pledged/Received	[4]	(13,400)	(22,221)
Net Amount		$ (60,761)	$ (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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ (2,258)	$ 2,100	$ (5,284)	$ 9,541
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ 2,832	$ (2,100)	$ 9,666	$ (9,541)

Derivative Instruments (Current

Derivative Instruments (Current Period Cash Flow Hedges in AOCI (loss) before Taxes) (Details) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2018	Sep. 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	$ (29,043)	$ (347)	$ (22,656)	$ (7,690)	$ (29,043)	$ (347)	$ (2,619)	$ 2,496
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	6,671	(6,889)			26,586	3,689
Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(50)	(271)			(270)	(704)
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	(183)			0	(142)
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (234)	$ 0			$ 108	$ 0

Derivative Instruments (Cash Fl

Derivative Instruments (Cash Flow Hedges) (Details) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2018	Sep. 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	$ 6,671	$ (6,889)			$ 26,586	$ 3,689
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	29,043	347	$ 22,656	$ 7,690	29,043	347	$ 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	183			0	142
Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	50	271			270	704
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	234	0			(108)	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	7,490	(8,421)			27,217	(6,205)
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	234	0			(108)	0
Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	(819)	1,544			(631)	9,894
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	50	230			270	560
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		(12)				0
Forward Contracts [Member] | Gain (Loss) on Investments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		183				142
Forward Contracts [Member] | Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		41				144
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		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	$ (17,439)	$ (30,571)	$ 22,862	$ (51,938)
Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	(5,877)	(35,198)	11,125	(60,723)
Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Net Derivatives Gains (Losses) Deferred in AOCI	[1],[2]	$ (11,562)	$ 4,627	$ 11,737	$ 8,785
[1]	There was no ineffectiveness recognized for the Company’s hedges of net investments in foreign operations.
[2]	There were no sales or substantial liquidations of net investments in foreign operations that would have required the reclassification of gains or losses from accumulated other comprehensive income (loss) into investment income during the periods presented.

Derivative Instruments (Non Hed

Derivative Instruments (Non Hedging Derivatives and Embedded Derivatives Effect on Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	$ (20,017)	$ 22,653	$ (31,059)	$ 139,471
Policy acquisition costs and other insurance expenses	(310,639)	(365,424)	(987,817)	(1,064,645)
Interest credited	143,292	126,099	333,068	349,068
Other revenues	112,764	75,942	272,020	218,091
Gain Loss On Investments Related To Change In Fair Value Of Derivatives Excluding Embedded Derivatives	(25,258)	(8,961)	(58,883)	(28,125)
Not Designated as Hedging Instrument
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(20,553)	(5,255)	30,217	59,757
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(12,228)	641	(47,399)	12,318
Not Designated as Hedging Instrument | Financial Futures
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(6,544)	(8,890)	(7,312)	(28,107)
Not Designated as Hedging Instrument | Foreign Currency Forwards
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(58)	24	3	577
Not Designated as Hedging Instrument | Consumer Price Index Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(4,223)	220	(996)	211
Not Designated as Hedging Instrument | Credit Default Swaps
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	4,689	4,137	5,371	15,374
Not Designated as Hedging Instrument | Equity Options
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(9,793)	(8,295)	(15,207)	(34,757)
Not Designated as Hedging Instrument | Longevity Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Other revenues	2,426	3,334	6,983	7,180
Not Designated as Hedging Instrument | Mortality Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Other revenues	473	(132)	(326)	(921)
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	(2,081)	23,044	20,335	106,854
Not Designated as Hedging Instrument | Embedded Derivatives In Indexed Annuity [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Interest credited	(25,347)	13,133	6,523	35,490
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	$ 32,133	$ (6,205)	$ 62,242	$ 16,518

Derivative Instruments (Exposur

Derivative Instruments (Exposure from Credit Derivatives by Rating of the Underlying Credits) (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 6,642	$ 7,572
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 1,153,300	$ 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]	$ 2,470	$ 3,128
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 152,000	$ 162,000
Derivative Average Remaining Maturity	[1],[3]	2 years 6 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]	$ 2,470	$ 3,128
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 152,000	$ 162,000
Derivative Average Remaining Maturity	[1],[3]	2 years 6 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]	$ 4,220	$ 4,469
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 343,700	$ 361,700
Derivative Average Remaining Maturity	[1],[3]	2 years 5 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]	$ (80)	$ (55)
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 642,600	$ 422,600
Derivative Average Remaining Maturity	[1],[3]	3 years 5 months	4 years
Standard Poors BBB Rating [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 4,140	$ 4,414
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 986,300	$ 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	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]	$ 32	$ 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]	32	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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 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	$ (25,258)	$ (8,961)	$ (58,883)	$ (28,125)
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	(2,081)	23,044	20,335	106,854
Derivative, Gain (Loss) on Derivative, Net	(1,320)	7,515	11,517	36,300
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	(25,347)	(13,133)	6,523	(35,490)
Derivative, Gain (Loss) on Derivative, Net	(17,311)	(9,737)	(6,808)	(38,059)
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	32,133	(6,205)	62,242	16,518
Derivative, Gain (Loss) on Derivative, Net	$ 9,463	$ (1,074)	$ 33,061	$ 30,785

Derivative Instruments (Credit

Derivative Instruments (Credit Exposure of Derivative Contracts) (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Credit Exposure of Derivative Contracts
Estimated fair value of derivatives in net asset (liability) position		$ 133,590	$ 155,714
Derivative, Collateral, Right to Reclaim Cash	[1]	13,400	22,221
Derivative Liability, Fair Value of Collateral	[2]	61,293	58,156
Derivative, Collateral, Obligation to Return Cash	[3]	(159,194)	(185,900)
Derivative Asset, Fair Value of Collateral	[4]	0	(862)
Deposits with Clearing Organizations and Others, Securities	[2]	(61,293)	(58,156)
Net credit exposure		(12,204)	(8,827)
Margin account related to exchange-traded futures	[5]	$ 8,348	$ 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	Sep. 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	$ 136.5	$ 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	0.2
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 1.9

Fair Value of Assets and Liab_3

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Balances of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 39,005,212	$ 38,150,820
Non Redeemable Preferred Stock Equity Method Investments Fair Value Disclosure		39,806
Equity Method Investments, Fair Value Disclosure	101,069	60,346
Funds withheld at interest embedded derivatives	142,529	122,194
Cash and cash equivalents	657,280	356,788
Short-term investments	186,051	50,746
Investments, Fair Value Disclosure	313,439	356,154
Other Assets, Fair Value Disclosure	46,090	40,659
Assets, Fair Value Disclosure	40,451,670	39,177,513
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	906,199	1,014,228
Liabilities Fair Value Disclosure
Financial Liabilities Fair Value Disclosure	920,131	1,038,469
Interest Rate Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	29,106	51,359
Liabilities Fair Value Disclosure
Other liabilities	(14,166)	(14,311)
Foreign Currency Forwards
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	6,881	730
Liabilities Fair Value Disclosure
Other liabilities		(7,213)
Consumer Price Index Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	(13)	(221)
Liabilities Fair Value Disclosure
Other liabilities	(2,696)	(1,939)
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	212,315	218,541
Credit Default Swaps
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	5,961	5,908
Liabilities Fair Value Disclosure
Other liabilities	(684)	(760)
Equity Option [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	16,818	16,932
Liabilities Fair Value Disclosure
Other liabilities	(2,554)	(6,339)
Currency Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	42,371	62,905
Liabilities Fair Value Disclosure
Other liabilities		(6,194)
Mortality Swap [Member]
Liabilities Fair Value Disclosure
Other liabilities	(308)	(1,683)
Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	24,449,498	23,210,968
Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	4,036,750	4,220,076
Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,780,762	1,719,880
Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,863,017	1,648,362
Assets, Fair Value Disclosure	64,475	0
Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,273,534	1,303,387
US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,412,409	1,943,592
US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	911,991	703,428
Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,277,251	3,401,127
Fair Value Inputs Level 1 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,284,932	1,818,006
Non Redeemable Preferred Stock Equity Method Investments Fair Value Disclosure		39,806
Equity Method Investments, Fair Value Disclosure	57,584	60,346
Funds withheld at interest embedded derivatives	0	0
Cash and cash equivalents	657,280	354,071
Short-term investments	5,957	0
Investments, Fair Value Disclosure	211,253	217,618
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	2,217,006	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
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	211,253	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	1,284,932	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	35,792,145	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	0	2,717
Short-term investments	177,891	47,650
Investments, Fair Value Disclosure	102,186	138,536
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	36,072,222	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	13,624	22,558
Fair Value Inputs Level 2 Member | Interest Rate Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	29,106	51,359
Liabilities Fair Value Disclosure
Other liabilities	(14,166)	(14,311)
Fair Value Inputs Level 2 Member | Foreign Currency Forwards
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	6,881	730
Liabilities Fair Value Disclosure
Other liabilities		(7,213)
Fair Value Inputs Level 2 Member | Consumer Price Index Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	(13)	(221)
Liabilities Fair Value Disclosure
Other liabilities	(2,696)	(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	1,062	923
Fair Value Inputs Level 2 Member | Credit Default Swaps
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	5,961	5,908
Liabilities Fair Value Disclosure
Other liabilities	(684)	(760)
Fair Value Inputs Level 2 Member | Equity Option [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	16,818	16,932
Liabilities Fair Value Disclosure
Other liabilities	(2,554)	(6,339)
Fair Value Inputs Level 2 Member | Currency Swap [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	42,371	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	23,193,563	21,873,696
Fair Value Inputs Level 2 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,488,008	3,626,134
Fair Value Inputs Level 2 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,780,762	1,611,998
Fair Value Inputs Level 2 Member | Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,780,250	1,524,888
Fair Value Inputs Level 2 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,271,752	1,300,153
Fair Value Inputs Level 2 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	107,225	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	898,346	662,225
Fair Value Inputs Level 2 Member | Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,272,239	3,396,035
Fair Value Inputs Level 3 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,928,135	2,234,610
Non Redeemable Preferred Stock Equity Method Investments Fair Value Disclosure		0
Equity Method Investments, Fair Value Disclosure	43,485	0
Funds withheld at interest embedded derivatives	142,529	122,194
Cash and cash equivalents	0	0
Short-term investments	2,203	3,096
Investments, Fair Value Disclosure	0	0
Other Assets, Fair Value Disclosure	46,090	40,659
Assets, Fair Value Disclosure	2,162,442	2,400,559
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	906,199	1,014,228
Liabilities Fair Value Disclosure
Financial Liabilities Fair Value Disclosure	906,507	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
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	(308)	(1,683)
Fair Value Inputs Level 3 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,255,935	1,337,272
Fair Value Inputs Level 3 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	548,742	593,942
Fair Value Inputs Level 3 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	107,882
Fair Value Inputs Level 3 Member | Asset-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	82,767	123,474
Fair Value Inputs Level 3 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,782	3,234
Fair Value Inputs Level 3 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	20,252	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	13,645	41,203
Fair Value Inputs Level 3 Member | Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 5,012	$ 5,092

Fair Value of Assets and Liab_4

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	9 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2017USD ($)
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	0	88,674

Fair Value of Assets and Liab_5

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Quantitative Information for Level 3 Inputs) (Details) $ in Thousands	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 40,451,670	$ 39,177,513
Corporate Debt Securities [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 630,328	$ 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	0.05	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
Asset-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 64,475	$ 0
Asset-backed securities | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0
Asset-backed securities | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Measurement Input	0.01	0
Asset-backed securities | 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	$ 46,090	$ 40,659
US Government Agencies Debt Securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 20,252	$ 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	0.01
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	0.01
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	$ 0	$ 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	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	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	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	$ 5,012	$ 0
Equity securities | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 33,074	$ 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	0.04	0
Equity securities | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	0.04	0
Equity securities | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	0.04	0
Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 142,529	$ 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	$ 815,970	$ 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	$ 90,229	$ 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	$ 308	$ 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	0.13	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	12.3	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 Liab_6

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Corporate Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		$ 1,367,154		$ 1,291,054		$ 1,337,272	$ 1,272,253
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(4,858)		(2,700)		(35,532)	(2,300)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		123,808	[1]	107,670	[1]	379,476	257,671	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(62,047)	[1]	(26,337)	[1]	79,316	49,511	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(101,868)	[1]	(88,551)	[1]	245,342	234,552	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		2,782		3,844		9,948	35,042
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(69,119)		(12,973)		106,847	12,973
Fair Value, end of period		1,255,935		1,272,020		1,255,935	1,272,020
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		(156)		(383)		(822)	(1,202)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(180)		(394)		(845)	(1,213)
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		239		396		(2,902)	7,592
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(1,430)				(4,571)	(2,788)
Canadian Provincial Governments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		572,698		533,270		593,942	475,965
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(27,476)		(11,365)		(55,632)	39,669
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	0	[1]	0	0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0	[1]	0	[1]	0	0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0	[1]	0	[1]	0	0	[1]
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		548,742		525,365		548,742	525,365
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		3,520		3,460		10,432	9,731
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		3,520		3,460		10,432	9,731
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
Residential mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		54,839		148,685		107,882	160,291
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(1)		104		(1,782)	2,716
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	26,765	[1]	45,328	72,582	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0	[1]	(3,553)	[1]	4,961	18,624	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(3)	[1]	(3,645)	[1]	4,538	15,084	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		15		3,031	5,515
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(54,838)		(50,390)		145,140	89,621
Fair Value, end of period		0		117,995		0	117,995
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		3		(30)		(132)	(304)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		(27)		0	(155)
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		0		44		312	524
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0				0	(346)
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		70,686		201,589		123,474	219,280
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(130)		(101)		(821)	6,802
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		11,099	[1]	0	[1]	22,099	45,215	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(462)	[1]	0	[1]	462	0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(24,166)	[1]	(15,243)	[1]	46,449	60,966	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		64,009		36,994		68,977	75,752
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(38,915)		(78,202)		86,163	142,575
Fair Value, end of period		82,767		145,197		82,767	145,197
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		20		160		202	1,689
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		13		156		187	556
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		626		0		1,910	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		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		16,505		34,434		41,203	41,666
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(544)		(208)		46	(228)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	0	[1]	0	0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(37)	[1]	35	[1]	158	309	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		9,859		7,295		9,859	7,295
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(12,144)		0		37,309	6,844
Fair Value, end of period		13,645		41,512		13,645	41,512
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		6		26		4	(68)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		6		26		3	(68)
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		5,044				5,092
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(32)				(80)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0	[1]			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0				0
Fair Value, end of period		5,012				5,012
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				11,994			12,869
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)				(7)			(210)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]			495			495
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]			0			672
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				6,853			6,853
Fair Value, end of period				5,628			5,628
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				(1)			(1)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				(1)			(1)
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		20,735		23,567		22,511	24,488
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(122)		6		(635)	269
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		120	[1]	134	[1]	334	370	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(374)	[1]	340	[1]	1,634	1,528	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0		0	0
Fair Value, end of period		20,252		23,251		20,252	23,251
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)		(116)		(324)	(348)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(107)		(116)		(325)	(348)
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		1,867		1,943		3,234	21,145
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		7		5		(56)	(57)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	0	[1]	0	0	[1]
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)	[1]	1	[1]	4	5,403	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		1,752		0		1,752	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(1,843)		0		3,144	10,132
Fair Value, end of period		1,782		1,947		1,782	1,947
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 Into Level 3		0		0		0	0
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		144,610		61,281		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
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0		0	0
Fair Value, end of period		142,529		84,325		142,529	84,325
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		(2,081)		23,044		20,335	106,854
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(2,081)		23,044		20,335	106,854
Funds Withheld At Interest Embedded Derivatives [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0		0	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0		0	0
Funds Withheld At Interest Embedded Derivatives [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0		0	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0		0	0
Longevity Swap [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		43,971		33,349		40,659	26,958
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(307)		1,144		(1,552)	3,689
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
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0		0	0
Fair Value, end of period		46,090		37,827		46,090	37,827
Longevity Swap [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0		0	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0		0	0
Longevity Swap [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0		0	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0		0	0
Longevity Swap [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		2,426		3,334		6,983	7,180
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		2,426		3,334		6,983	7,180
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
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		(928,797)		(974,631)		(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]	(4,231)		(18,736)		(16,946)	(51,276)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	20,044		21,809		56,210	63,047
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0		0	0
Fair Value, end of period		(906,199)		(989,940)		(906,199)	(989,940)
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		(32,133)		10,047		(62,242)	(9,005)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(30,433)		11,900		(56,808)	(2,934)
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		(25,348)		(8,335)		6,523	(20,408)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		45,393		30,145		49,688	83,456
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
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		782		1,552		1,683	2,462
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		1		1		1	1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	[1]	0		0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	0		0		1,700	1,700
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0		0	0
Fair Value, end of period		(308)		(1,683)		(308)	(1,683)
Mortality Swap [Member] | Gain (Loss) on Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0		0	0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0		0	0
Mortality Swap [Member] | Interest Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0		0	0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0		0	0
Mortality Swap [Member] | Other Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		(473)		132		326	922
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(473)		132		(326)	922
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		42,937				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		863				13,111
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		5,847				6,416
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0				48
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3						38,905
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0				0
Fair Value, end of period		43,485				43,485
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		5,532				(2,067)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		2,178				(5,527)
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 | 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		3,548		3,096	3,346
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		47		(3)		1	1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		1,721	[1]	3,164	[1]	2,202	3,520	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0	[1]			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0	[1]	(114)	[1]	314	(272)	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		2,782		3,236		2,782	3,236
Fair Value, end of period		2,203		3,359		2,203	3,359
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. | 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. | 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 Liab_7

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Fair Value Assets Measured on Non-Recurring Basis) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Partnership Interest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets Carrying Value Prior To Impairment	[1]				$ 2,246		$ 4,656
Fair Value Assets Gains Losses		$ (1,860)	[1]	$ (896)	(1,860)	[1]	(7,204)	[1]
Private Equity Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets Carrying Value Prior To Impairment	[2]				0		106
Fair Value Assets Gains Losses	[2]	$ 0		$ (531)	$ 0		$ (531)
[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.
[2]	The fair value of the Company’s private equity investments is based on external valuation models.

Fair Value of Assets and Liab_8

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) - USD ($) $ in Thousands		Sep. 30, 2018		Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Assets
Mortgage loans on real estate (net of valuation allowances)		$ 4,779,074		$ 4,400,533
Policy loans		1,320,050		1,357,624
Funds withheld at interest		5,976,301		6,083,388
Cash and cash equivalents		1,730,489		1,303,524	$ 1,204,590	$ 1,200,718
Short-term investments		229,928		93,304
Other invested assets		1,706,979		1,505,332
Accrued investment income		455,296		392,721
Liabilities
Interest-sensitive contract liabilities		16,751,379		16,227,642
Long-term debt		2,787,975		2,788,365
Collateral finance and securitization notes		710,792		783,938
Reported Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)	[1]	4,779,074		4,400,533
Policy loans	[1]	1,320,050		1,357,624
Funds withheld at interest	[1]	5,833,925		5,955,092
Cash and cash equivalents	[1]	1,073,209		946,736
Short-term investments	[1]	43,877		42,558
Other invested assets	[1]	842,626		651,792
Accrued investment income	[1]	455,296		392,721
Liabilities
Interest-sensitive contract liabilities	[1]	13,319,348		12,683,872
Long-term debt	[1]	2,787,975
Debt, Long-term and Short-term, Combined Amount	[1]			2,788,365
Collateral finance and securitization notes	[1]	710,792		783,938
Estimate of Fair Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)		4,652,481		4,477,654
Policy loans		1,320,050		1,357,624
Funds withheld at interest		6,040,671		6,275,623
Cash and cash equivalents		1,073,209		946,736
Short-term investments		43,877		42,558
Other invested assets		839,280		679,377
Accrued investment income		455,296		392,721
Liabilities
Interest-sensitive contract liabilities		13,113,427	[1]	12,917,243
Long-term Debt, Fair Value		2,850,344
Debt, Long-term and Short-term, Combined Amount				2,959,912
Collateral finance and securitization notes		652,380		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		1,073,209		946,736
Short-term investments		43,877		42,558
Other invested assets		5,618		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		1,320,050		1,357,624
Funds withheld at interest		0		0
Cash and cash equivalents		0		0
Short-term investments		0		0
Other invested assets		71,401		67,778
Accrued investment income		455,296		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)		4,652,481		4,477,654
Policy loans		0		0
Funds withheld at interest		6,040,671		6,275,623
Cash and cash equivalents		0		0
Short-term investments		0		0
Other invested assets		382,284		247,934
Accrued investment income		0		0
Liabilities
Interest-sensitive contract liabilities		13,113,427		12,917,243
Long-term Debt, Fair Value		2,850,344
Debt, Long-term and Short-term, Combined Amount				2,959,912
Collateral finance and securitization notes		652,380		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		379,977		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.September 30, 2018: Carrying Value (1) Estimated Fair Value Fair Value Measurement Using:Level 1 Level 2 Level 3 NAVAssets: Mortgage loans on real estate $4,779,074 $4,652,481 $— $— $4,652,481 $—Policy loans 1,320,050 1,320,050 — 1,320,050 — —Funds withheld at interest 5,833,925 6,040,671 — — 6,040,671 —Cash and cash equivalents 1,073,209 1,073,209 1,073,209 — — —Short-term investments 43,877 43,877 43,877 — — —Other invested assets 842,626 839,280 5,618 71,401 382,284 379,977Accrued investment income 455,296 455,296 — 455,296 — —Liabilities: Interest-sensitive contract liabilities $13,319,348 $13,113,427 $— $— $13,113,427 $—Long-term debt 2,787,975 2,850,344 — — 2,850,344 —Collateral finance and securitization notes 710,792 652,380 — — 652,380 — 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 Liab_9

Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Narrative) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
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	$ 38,905

Segment Information (Total Reve

Segment Information (Total Revenues of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 3,227,531	$ 3,145,310	$ 9,597,146	$ 9,283,326
Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,838,638	1,785,553	5,335,779	5,367,576
CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	308,130	293,525	947,514	850,883
EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	448,723	438,013	1,403,861	1,255,413
Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	594,202	578,592	1,817,099	1,683,787
Corporate and Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	37,838	49,627	92,893	125,667
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,547,790	1,521,383	4,601,631	4,532,584
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	295,962	281,095	910,480	814,643
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	357,059	360,972	1,123,379	1,024,978
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	578,035	561,660	1,763,094	1,628,419
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	290,848	264,170	734,148	834,992
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	12,168	12,430	37,034	36,240
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	91,664	77,041	280,482	230,435
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 16,167	$ 16,932	$ 54,005	$ 55,368

Segment Information (Income Los

Segment Information (Income Loss Before Provision for Income Tax of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 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	$ 322,661	$ 340,162	$ 707,874	$ 887,321
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	203,401	249,630	428,080	580,755
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	22,795	33,261	75,042	93,442
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	74,575	46,374	200,997	132,527
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	62,213	26,335	152,121	132,594
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	(40,323)	(15,438)	(148,366)	(51,997)
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	116,328	160,512	191,198	281,066
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	21,149	28,789	66,661	80,953
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	18,370	15,421	40,259	40,751
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	62,007	26,564	143,756	121,574
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	87,073	89,118	236,882	299,689
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	1,646	4,472	8,381	12,489
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	56,205	30,953	160,738	91,776
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	$ 206	$ (229)	$ 8,365	$ 11,020

Segment Information (Total Asse

Segment Information (Total Assets of Reportable Segments) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 62,972,642	$ 60,514,818
Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	38,400,622	34,562,629
CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,356,425	4,287,824
EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	8,158,746	8,374,488
Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,494,776	6,114,027
Corporate and Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,562,073	7,175,850
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,148,790	18,603,423
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,210,051	4,161,452
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,573,449	3,099,495
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,312,822	4,915,442
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,251,832	15,959,206
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	146,374	126,372
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,585,297	5,274,993
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 1,181,954	$ 1,198,585

Commitments, Contingencies an_3

Commitments, Contingencies and Guarantees (Commitments to Fund Investments) (Details) - USD ($) $ in Thousands	Sep. 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	$ 578,944	$ 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	120,571	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	101,992	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	$ 213,459	$ 153,937

Commitments, Contingencies an_4

Commitments, Contingencies and Guarantees (Maximum Potential Obligation) (Details) $ in Millions	Sep. 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 an_5

Commitments, Contingencies and Guarantees (Guarantees Issued) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Insurance Treaty Guarantee [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 1,073,184	$ 1,047,449
Insurance Treaty Guarantee Net Of Assets Held In Trust [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	966,099	926,393
Guarantee Of Borrowed Securities [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	276,190	294,325
Product Financing Arrangement [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	69,221	86,183
Guarantee Of Lease Obligations [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 881	$ 1,662

Income Tax (Provision for Incom

Income Tax (Provision for Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 67,759	$ 119,057	$ 148,654	$ 310,562
Tax Adjustments, Settlements, and Unusual Provisions	664	0	(2,685)	0
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(58,949)	0	(59,139)	0
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	7,537	(3,635)	8,795	(14,049)
Income Tax Reconciliation Foreign Income Tax Basis Differential	(2,371)	2,126	(9,264)	(14,633)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	(5,334)	(2,501)	5,357	11,627
Effective Income Tax Rate Reconciliation, Tax Contingency, Domestic, Amount	1,851	299	650	(873)
Income Tax Reconciliation Change In Foreign Enacted Tax Rate	(166)	(1,139)	30	(2,332)
Income Tax Reconciliation SubpartF	(99)	64	211	1,390
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount	(544)	1,230	(1,003)	(834)
Effective Income Tax Rate Reconciliation Global Intangible Low Taxed Income	7,624	0	11,916	0
Effective Income Tax Rate Reconciliation, Equity in Earnings (Losses) of Unconsolidated Subsidiary, Amount	817	2,762	5,067	7,226	$ 10,500
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount	4,213	452	4,108	133
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	94	(620)	(492)	(1,737)
Income Tax Expense (Benefit)	$ 21,462	$ 112,571	$ 102,071	$ 282,028
Effective Income Tax Rate Reconciliation, Percent	6.70%	33.10%	14.40%	31.80%

Income Tax Income Tax (Narrativ

Income Tax Income Tax (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ 2,573		$ 156,400
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 58,949	$ 0	$ 59,139	$ 0

Employee Benefit Plans (Defined

Employee Benefit Plans (Defined Benefit Plans Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,106	$ 2,699	$ 9,330	$ 8,098
Interest cost	1,341	1,314	4,028	3,943
Expected return on plan assets	(1,884)	(1,554)	(5,651)	(4,662)
Amortization of prior service cost	82	85	247	254
Amortization of prior actuarial loss	929	1,081	2,792	3,244
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	256	0	769
Total	3,574	3,881	10,746	11,646
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	999	465	2,271	1,907
Interest cost	680	459	1,739	1,589
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(328)	(675)	(986)	(986)
Amortization of prior actuarial loss	937	580	1,933	1,494
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0	0
Total	$ 2,288	$ 829	$ 4,957	$ 4,004

Reinsurance (Ceded Reinsurance

Reinsurance (Ceded Reinsurance Receivable Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 769,324	$ 782,027
Reinsurance Recoverables, Percentage of Total	100.00%	100.00%
Other Reinsurers [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 117,942	$ 127,808
Reinsurance Recoverables, Percentage of Total	15.30%	16.20%
AM Best, A+ Rating [Member] | Reinsurer A [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 303,942	$ 301,478
Reinsurance Recoverables, Percentage of Total	39.50%	38.60%
AM Best, A+ Rating [Member] | Reinsurer B [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 203,702	$ 203,898
Reinsurance Recoverables, Percentage of Total	26.50%	26.10%
AM Best, A+ Rating [Member] | Reinsurer D [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 41,049	$ 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	$ 67,599	$ 67,723
Reinsurance Recoverables, Percentage of Total	8.80%	8.70%
AM Best, A++ Rating [Member] | Reinsurer E [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 35,090	$ 40,592
Reinsurance Recoverables, Percentage of Total	4.60%	5.20%

Reinsurance (Narrative) (Detail

Reinsurance (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Ceded Credit Risk [Line Items]
Reinsurance Claims Recoverables	$ 269.1	$ 243.8
Claims Recoverable From Retrocessionaires Past Due	$ 6.7	$ 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++

Financing Activities (Details)

Financing Activities (Details) - Revolving Credit Facility [Member] $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Covenant Terms	five year term
Line of Credit Facility, Maximum Borrowing Capacity	$ 850
Line of Credit Facility, Borrowing Capacity, Description	The Company may borrow cash and may obtain letters of credit in multiple currencies under this facility.

New Accounting Standards New Ac

New Accounting Standards New Accounting Standards (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ 2,573		$ 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	$ 817	$ 2,762	$ 5,067	$ 7,226	10,500
Contractual Obligation					$ 38,200