Summary of Investments | Summary of Investments The following tables summarize fixed maturity investments classified as available-for-sale and the non-credit-related component of OTTI in AOCI: December 31, 2016 Amortized Gross unrealized Gross unrealized Estimated fair value OTTI (gain) loss Fixed maturities: cost gains losses and carrying value included in AOCI (1) U.S. government direct obligations and U.S. agencies $ 3,022,279 $ 47,791 $ 34,958 $ 3,035,112 $ — Obligations of U.S. states and their subdivisions 1,890,568 214,411 6,317 2,098,662 — Corporate debt securities (2) 13,811,597 477,316 309,164 13,979,749 (1,488 ) Asset-backed securities 1,226,493 104,274 18,388 1,312,379 (72,464 ) Residential mortgage-backed securities 138,292 3,867 1,167 140,992 23 Commercial mortgage-backed securities 1,222,257 23,207 20,182 1,225,282 — Collateralized debt obligations 361,241 339 53 361,527 — Total fixed maturities $ 21,672,727 $ 871,205 $ 390,229 $ 22,153,703 $ (73,929 ) (1) Indicates the amount of any OTTI (gain) loss included in AOCI that is included in gross unrealized gains and losses. OTTI (gain) loss included in AOCI, as presented above, includes both the initial recognition of non-credit losses and the effects of subsequent increases and decreases in estimated fair value for those fixed maturity securities with previous non-credit impairment. The non-credit loss component of OTTI (gain) loss was in an unrealized gain position due to increases in estimated fair value subsequent to initial recognition of non-credit losses on such securities. (2) Includes perpetual debt investments with amortized cost of $135,187 and estimated fair value of $113,239 . December 31, 2015 Amortized Gross unrealized Gross unrealized Estimated fair value OTTI (gain) loss Fixed maturities: cost gains losses and carrying value included in AOCI (1) U.S. government direct obligations and U.S. agencies $ 3,291,167 $ 55,193 $ 4,608 $ 3,341,752 $ — Obligations of U.S. states and their subdivisions 1,988,214 238,862 7,903 2,219,173 50 Foreign government securities 2,291 — 5 2,286 — Corporate debt securities (2) 12,388,886 437,207 320,381 12,505,712 (1,810 ) Asset-backed securities 1,196,326 128,406 13,362 1,311,370 (86,474 ) Residential mortgage-backed securities 122,146 4,734 1,508 125,372 (123 ) Commercial mortgage-backed securities 1,009,320 19,117 11,529 1,016,908 — Collateralized debt obligations 9,112 — 58 9,054 — Total fixed maturities $ 20,007,462 $ 883,519 $ 359,354 $ 20,531,627 $ (88,357 ) (1) Indicates the amount of any OTTI (gain) loss included in AOCI that is included in gross unrealized gains and losses. OTTI (gain) loss included in AOCI, as presented above, includes both the initial recognition of non-credit losses and the effects of subsequent increases and decreases in estimated fair value for those fixed maturity securities with previous non-credit impairment. The non-credit loss component of OTTI (gain) loss was in an unrealized gain position due to increases in estimated fair value subsequent to initial recognition of non-credit losses on such securities. (2) Includes perpetual debt investments with amortized cost of $149,062 and estimated fair value of $116,423 . See Note 8 for additional discussion regarding fair value measurements. The amortized cost and estimated fair value of fixed maturity investments classified as available-for-sale, based on estimated cash flows, are shown in the table below. Actual maturities will likely differ from these projections because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. December 31, 2016 Amortized cost Estimated fair value Maturing in one year or less $ 668,305 $ 690,369 Maturing after one year through five years 3,741,043 3,917,479 Maturing after five years through ten years 6,570,148 6,650,854 Maturing after ten years 5,088,280 5,208,071 Mortgage-backed and asset-backed securities 5,604,951 5,686,930 Total fixed maturities $ 21,672,727 $ 22,153,703 Mortgage-backed (commercial and residential) and asset-backed securities include those issued by the U.S. government and U.S. agencies. The following table summarizes information regarding the sales of securities classified as available-for-sale: Year Ended December 31, 2016 2015 2014 Proceeds from sales $ 4,541,303 $ 4,187,547 $ 2,705,999 Gross realized gains from sales 84,305 47,965 47,852 Gross realized losses from sales 16,858 6,476 1,229 Mortgage loans on real estate - The following table summarizes the carrying value of the mortgage loan portfolio by component: December 31, 2016 December 31, 2015 Principal $ 3,558,863 $ 3,242,627 Unamortized premium (discount) and fees, net 5,541 7,967 Foreign exchange translation (2,696 ) — Mortgage provision allowance (2,882 ) (2,890 ) Total mortgage loans $ 3,558,826 $ 3,247,704 The following table summarizes the recorded investment of the mortgage loan portfolio by risk assessment category as of December 31, 2016 , and 2015 , respectively. December 31, 2016 December 31, 2015 Performing $ 3,560,243 $ 3,249,129 Non-performing 1,465 1,465 Total $ 3,561,708 $ 3,250,594 The following table summarizes activity in the mortgage provision allowance: Year Ended December 31, 2016 2015 2014 Commercial mortgages Commercial mortgages Commercial mortgages Beginning balance $ 2,890 $ 2,890 $ 2,890 Provision increases 536 — — Provision decreases (544 ) — — Ending balance $ 2,882 $ 2,890 $ 2,890 Allowance ending balance by basis of impairment method: Individually evaluated for impairment $ 536 $ — $ — Collectively evaluated for impairment 2,346 2,890 2,890 Recorded investment balance in the mortgage loan portfolio, gross of allowance, by basis of impairment method: $ 3,561,708 $ 3,250,594 $ 3,366,460 Individually evaluated for impairment 1,465 14,031 12,986 Collectively evaluated for impairment 3,560,243 3,236,563 3,353,474 Limited partnership and other corporation interests - At December 31, 2016 , and 2015 , the Company had $34,895 and $40,980 , respectively, invested in limited partnership and other corporation interests. Limited partnership interests represent the Company’s minority ownership interests in pooled investment funds that primarily make private equity investments across diverse industries and geographical focuses. The Company has determined its interest in each limited partnership to be considered a VIE. Consolidation is not required as the Company is not deemed to be the primary beneficiary of the VIEs. The carrying value and maximum exposure to loss in relation to the activities of the VIEs was $32,444 and $38,504 at December 31, 2016 , and 2015 , respectively. Special deposits - The Company had securities on deposit with government authorities as required by certain insurance laws with fair values of $7,659 and $14,000 at December 31, 2016 , and 2015 , respectively. Securities lending - The Company had no securities on loan under the program, and therefore no cash or securities held as collateral, at December 31, 2016 , and 2015 . Unrealized losses on fixed maturity investments classified as available-for-sale - The following tables summarize unrealized investment losses, including the non-credit-related portion of OTTI losses reported in AOCI, by class of investment: December 31, 2016 Less than twelve months Twelve months or longer Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fixed maturities: fair value loss and OTTI fair value loss and OTTI fair value loss and OTTI U.S. government direct obligations and U.S. agencies $ 2,006,588 $ 34,752 $ 10,526 $ 206 $ 2,017,114 $ 34,958 Obligations of U.S. states and their subdivisions 216,154 5,922 10,498 395 226,652 6,317 Corporate debt securities 4,119,630 170,453 860,153 138,711 4,979,783 309,164 Asset-backed securities 316,065 6,971 230,331 11,417 546,396 18,388 Residential mortgage-backed securities 16,962 102 14,297 1,065 31,259 1,167 Commercial mortgage-backed securities 592,508 17,535 26,068 2,647 618,576 20,182 Collateralized debt obligations 160,612 53 — — 160,612 53 Total fixed maturities $ 7,428,519 $ 235,788 $ 1,151,873 $ 154,441 $ 8,580,392 $ 390,229 Total number of securities in an unrealized loss position 610 128 738 December 31, 2015 Less than twelve months Twelve months or longer Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fixed maturities: fair value loss and OTTI fair value loss and OTTI fair value loss and OTTI U.S. government direct obligations and U.S. agencies $ 1,357,822 $ 4,101 $ 23,604 $ 507 $ 1,381,426 $ 4,608 Obligations of U.S. states and their subdivisions 267,581 7,903 — — 267,581 7,903 Foreign government securities 2,286 5 — — 2,286 5 Corporate debt securities 4,412,965 202,874 552,791 117,507 4,965,756 320,381 Asset-backed securities 247,082 4,372 182,404 8,990 429,486 13,362 Residential mortgage-backed securities — — 18,625 1,508 18,625 1,508 Commercial mortgage-backed securities 429,175 11,154 44,498 375 473,673 11,529 Collateralized debt obligations 9,054 58 — — 9,054 58 Total fixed maturities $ 6,725,965 $ 230,467 $ 821,922 $ 128,887 $ 7,547,887 $ 359,354 Total number of securities in an unrealized loss position 558 106 664 Fixed maturity investments - Total unrealized losses and OTTI increased by $30,875 , or 9% , from December 31, 2015 , to December 31, 2016 . The overall increase in unrealized losses was across several asset classes and reflects higher interest rates at December 31, 2016 , compared to December 31, 2015 , resulting in generally lower valuations of these fixed maturity securities. Total unrealized losses greater than twelve months increased by $25,554 from December 31, 2015 , to December 31, 2016 . Corporate debt securities account for 90% , or $138,711 , of the unrealized losses and OTTI greater than twelve months at December 31, 2016 . Non-investment grade corporate debt securities account for $13,285 of the unrealized losses and OTTI greater than twelve months, and $6,791 of the losses are on perpetual debt investments issued by investment grade rated banks in the United Kingdom. Management does not have the intent to sell these assets; therefore, an OTTI was not recognized in earnings. Asset-backed securities account for 7% of the unrealized losses and OTTI greater than twelve months at December 31, 2016 . The present value of the cash flows expected to be collected is not less than amortized cost and management does not have the intent to sell these assets; therefore, an OTTI was not recognized in earnings. Other-than-temporary impairment recognition - The OTTI on fixed maturity securities where the loss portion is bifurcated and the credit related component is recognized in realized investment gains (losses) is summarized as follows: Year Ended December 31, 2016 2015 2014 Beginning balance $ 102,343 $ 119,532 $ 167,961 Initial impairments - credit loss on securities not previously impaired — 759 — Reductions: Due to sales, maturities, or payoffs during the period (1,785 ) (559 ) (646 ) Due to increases in cash flows expected to be collected that are recognized over the remaining life of the security (16,893 ) (17,389 ) (47,783 ) Ending balance $ 83,665 $ 102,343 $ 119,532 Net Investment Income The following table summarizes net investment income: Year Ended December 31, 2016 2015 2014 Investment income: Fixed maturity and short-term investments $ 819,047 $ 796,133 $ 816,907 Mortgage loans on real estate 142,478 150,284 149,497 Policy loans 199,737 206,081 207,013 Limited partnership interests 1,759 10,462 9,128 Net interest on funds withheld balances under reinsurance agreements, related party 22,045 22,165 21,295 Derivative instruments (1) 100,007 78,655 39,533 Other 10,468 9,228 5,008 1,295,541 1,273,008 1,248,381 Investment expenses (18,982 ) (18,578 ) (19,993 ) Net investment income $ 1,276,559 $ 1,254,430 $ 1,228,388 (1) Includes gains (losses) on the hedged asset for fair value hedges. Realized Investment Gains (Losses) The following table summarizes realized investment gains (losses): Year Ended December 31, 2016 2015 2014 Realized investment gains (losses): Fixed maturity and short-term investments $ 87,108 $ 46,027 $ 54,219 Derivative instruments (5,318 ) 5,840 90,504 Mortgage loans on real estate 10,972 31,841 6,857 Other 120 2 (4,209 ) Realized investment gains (losses) $ 92,882 $ 83,710 $ 147,371 Included in net investment income and realized investment gains (losses) are amounts allocable to the participating fund account. This allocation is based upon the activity in a specific block of investments that are segmented for the benefit of the participating fund account. |