Condensed Consolidating Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ 1,578	$ 3,591	$ 3,248
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	8,325	8,112	8,327
Equity securities, available-for-sale	54	104	76
Mortgage loans on real estate	955	747	1,088
Limited partnerships/corporations	236	306	258
Acquisition of:
Fixed maturities	(8,719)	(9,839)	(8,759)
Equity securities, available-for-sale	(47)	(47)	(137)
Mortgage loans on real estate	(1,638)	(1,481)	(1,381)
Limited partnerships/corporations	(332)	(367)	(417)
Short-term investments, net	(80)	31	468
Derivatives, net	213	(24)	(141)
Sales from consolidated investment entities	2,047	2,304	5,432
Purchases within consolidated investment entities	(2,036)	(1,727)	(7,521)
Issuance of intercompany loans with maturities more than three months	0
Maturity of intercompany loans with maturities more than three months	0		0
Maturity (issuance) of short-term intercompany loans, net	0	0	0
Return of capital contributions and dividends from subsidiaries	0	0	0
Capital contributions to subsidiaries	0	0	0
Collateral (delivered) received, net	(148)	(22)	39
Other, net	3	20	57
Net cash provided by (used in) investing activities - discontinued operations	(1,261)	(1,800)	(1,663)
Net cash used in investing activities	(2,428)	(3,683)	(4,274)
Cash Flows from Financing Activities:
Deposits received for investment contracts	5,061	5,891	5,298
Maturities and withdrawals from investment contracts	(5,372)	(5,412)	(4,587)
Proceeds from issuance of debt with maturities of more than three months	399	798	0
Repayment of debt with maturities of more than three months	(490)	(708)	(31)
Debt issuance costs	(3)	(16)	(7)
Proceeds of intercompany loans with maturities of more than three months	0
Intercompany loans with maturities of more than three months	0		0
Net proceeds from short-term loans to subsidiaries	0	0	0
Return of capital contributions and dividends to parent	0	0	0
Contributions of capital from parent	0	0	0
Borrowings of consolidated investment entities	967	126	1,373
Repayments of borrowings of consolidated investment entities	(804)	(455)	(479)
Contributions from (distributions to) participants in consolidated investment entities	449	51	662
Proceeds from issuance of common stock, net	3	1	0
Share-based compensation	(8)	(7)	(5)
Common stock acquired - Share repurchase	(923)	(687)	(1,487)
Dividends paid	(8)	(8)	(9)
Net cash provided by (used in) financing activities - discontinued operations	384	916	280
Net cash (used in) provided by financing activities	(345)	490	1,008
Net increase (decrease) in cash and cash equivalents	(1,195)	398	(18)
Cash and cash equivalents, beginning of period	2,911	2,513	2,531
Cash and cash equivalents, end of period	1,716	2,911	2,513
Less: Cash and cash equivalents of discontinued operations, end of period	498	815	696
Cash and cash equivalents of continuing operations, end of period	1,218	2,096	1,817
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(232)	(270)	(517)
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	0	0	0
Equity securities, available-for-sale	0	0	0
Mortgage loans on real estate	0	0	0
Limited partnerships/corporations	0	0	0
Acquisition of:
Fixed maturities	0	0	0
Equity securities, available-for-sale	0	0	0
Mortgage loans on real estate	0	0	0
Limited partnerships/corporations	0	0	0
Short-term investments, net	0	0	0
Derivatives, net	0	0	0
Sales from consolidated investment entities	0	0	0
Purchases within consolidated investment entities	0	0	0
Issuance of intercompany loans with maturities more than three months	34
Maturity of intercompany loans with maturities more than three months	(34)		(1)
Maturity (issuance) of short-term intercompany loans, net	321	(41)	162
Return of capital contributions and dividends from subsidiaries	(2,044)	(1,682)	(2,665)
Capital contributions to subsidiaries	514	279	15
Collateral (delivered) received, net	0	0	0
Other, net	0	0	0
Net cash provided by (used in) investing activities - discontinued operations	0	0	0
Net cash used in investing activities	(1,209)	(1,444)	(2,489)
Cash Flows from Financing Activities:
Deposits received for investment contracts	0	0	0
Maturities and withdrawals from investment contracts	0	0	0
Proceeds from issuance of debt with maturities of more than three months	0	0
Repayment of debt with maturities of more than three months	0	0	0
Debt issuance costs	0	0	0
Proceeds of intercompany loans with maturities of more than three months	(34)
Intercompany loans with maturities of more than three months	34		1
Net proceeds from short-term loans to subsidiaries	(321)	41	(162)
Return of capital contributions and dividends to parent	2,276	1,952	3,182
Contributions of capital from parent	(514)	(279)	(15)
Borrowings of consolidated investment entities	0	0	0
Repayments of borrowings of consolidated investment entities	0	0	0
Contributions from (distributions to) participants in consolidated investment entities	0	0	0
Proceeds from issuance of common stock, net	0	0
Share-based compensation	0	0	0
Common stock acquired - Share repurchase	0	0	0
Dividends paid	0	0	0
Net cash provided by (used in) financing activities - discontinued operations	0	0	0
Net cash (used in) provided by financing activities	1,441	1,714	3,006
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of period	0	0	0
Cash and cash equivalents, end of period	0	0	0
Less: Cash and cash equivalents of discontinued operations, end of period	0	0	0
Cash and cash equivalents of continuing operations, end of period	0	0	0
Parent Issuer
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(22)	(308)	130
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	0	0	0
Equity securities, available-for-sale	25	18	24
Mortgage loans on real estate	0	0	0
Limited partnerships/corporations	0	0	0
Acquisition of:
Fixed maturities	0	0	0
Equity securities, available-for-sale	(34)	(23)	(31)
Mortgage loans on real estate	0	0	0
Limited partnerships/corporations	0	0	0
Short-term investments, net	0	0	(212)
Derivatives, net	0	1	(33)
Sales from consolidated investment entities	0	0	0
Purchases within consolidated investment entities	0	0	0
Issuance of intercompany loans with maturities more than three months	(34)	0	0
Maturity of intercompany loans with maturities more than three months	34	0	1
Maturity (issuance) of short-term intercompany loans, net	87	52	(162)
Return of capital contributions and dividends from subsidiaries	1,020	922	1,467
Capital contributions to subsidiaries	(467)	(215)	0
Collateral (delivered) received, net	0	0	20
Other, net	0	0	0
Net cash provided by (used in) investing activities - discontinued operations	0	0	0
Net cash used in investing activities	631	755	1,074
Cash Flows from Financing Activities:
Deposits received for investment contracts	0	0	0
Maturities and withdrawals from investment contracts	0	0	0
Proceeds from issuance of debt with maturities of more than three months	399	798	0
Repayment of debt with maturities of more than three months	(490)	(660)	0
Debt issuance costs	(3)	(16)	(7)
Proceeds of intercompany loans with maturities of more than three months	0
Intercompany loans with maturities of more than three months	0		0
Net proceeds from short-term loans to subsidiaries	408	11	0
Return of capital contributions and dividends to parent	0	0	0
Contributions of capital from parent	0	0	0
Borrowings of consolidated investment entities	0	0	0
Repayments of borrowings of consolidated investment entities	0	0	0
Contributions from (distributions to) participants in consolidated investment entities	0	0	0
Proceeds from issuance of common stock, net	3	1	0
Share-based compensation	(8)	(7)	(5)
Common stock acquired - Share repurchase	(923)	(687)	(1,487)
Dividends paid	(8)	(8)	(9)
Net cash provided by (used in) financing activities - discontinued operations	0	0	0
Net cash (used in) provided by financing activities	(622)	(568)	(1,508)
Net increase (decrease) in cash and cash equivalents	(13)	(121)	(304)
Cash and cash equivalents, beginning of period	257	378	682
Cash and cash equivalents, end of period	244	257	378
Less: Cash and cash equivalents of discontinued operations, end of period	0	0	0
Cash and cash equivalents of continuing operations, end of period	244	257	378
Subsidiary Guarantor
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	138	173	260
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	0	0	0
Equity securities, available-for-sale	0	0	0
Mortgage loans on real estate	0	0	0
Limited partnerships/corporations	0	0	0
Acquisition of:
Fixed maturities	0	0	0
Equity securities, available-for-sale	0	0	0
Mortgage loans on real estate	0	0	0
Limited partnerships/corporations	0	0	0
Short-term investments, net	0	0	0
Derivatives, net	0	0	0
Sales from consolidated investment entities	0	0	0
Purchases within consolidated investment entities	0	0	0
Issuance of intercompany loans with maturities more than three months	0
Maturity of intercompany loans with maturities more than three months	0		0
Maturity (issuance) of short-term intercompany loans, net	0	0	0
Return of capital contributions and dividends from subsidiaries	1,024	760	1,198
Capital contributions to subsidiaries	(47)	(64)	(15)
Collateral (delivered) received, net	0	0	0
Other, net	0	0	14
Net cash provided by (used in) investing activities - discontinued operations	0	0	0
Net cash used in investing activities	977	696	1,197
Cash Flows from Financing Activities:
Deposits received for investment contracts	0	0	0
Maturities and withdrawals from investment contracts	0	0	0
Proceeds from issuance of debt with maturities of more than three months	0	0
Repayment of debt with maturities of more than three months	0	(48)	(31)
Debt issuance costs	0	0	0
Proceeds of intercompany loans with maturities of more than three months	0
Intercompany loans with maturities of more than three months	0		0
Net proceeds from short-term loans to subsidiaries	(143)	5	57
Return of capital contributions and dividends to parent	(1,020)	(892)	(1,467)
Contributions of capital from parent	47	50	0
Borrowings of consolidated investment entities	0	0	0
Repayments of borrowings of consolidated investment entities	0	0	0
Contributions from (distributions to) participants in consolidated investment entities	0	0	0
Proceeds from issuance of common stock, net	0	0
Share-based compensation	0	0	0
Common stock acquired - Share repurchase	0	0	0
Dividends paid	0	0	0
Net cash provided by (used in) financing activities - discontinued operations	0	0	0
Net cash (used in) provided by financing activities	(1,116)	(885)	(1,441)
Net increase (decrease) in cash and cash equivalents	(1)	(16)	16
Cash and cash equivalents, beginning of period	2	18	2
Cash and cash equivalents, end of period	1	2	18
Less: Cash and cash equivalents of discontinued operations, end of period	0	0	0
Cash and cash equivalents of continuing operations, end of period	1	2	18
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	1,694	3,996	3,375
Proceeds from the sale, maturity, disposal or redemption of:
Fixed maturities	8,325	8,112	8,327
Equity securities, available-for-sale	29	86	52
Mortgage loans on real estate	955	747	1,088
Limited partnerships/corporations	236	306	258
Acquisition of:
Fixed maturities	(8,719)	(9,839)	(8,759)
Equity securities, available-for-sale	(13)	(24)	(106)
Mortgage loans on real estate	(1,638)	(1,481)	(1,381)
Limited partnerships/corporations	(332)	(367)	(417)
Short-term investments, net	(80)	31	680
Derivatives, net	213	(25)	(108)
Sales from consolidated investment entities	2,047	2,304	5,432
Purchases within consolidated investment entities	(2,036)	(1,727)	(7,521)
Issuance of intercompany loans with maturities more than three months	0
Maturity of intercompany loans with maturities more than three months	0		0
Maturity (issuance) of short-term intercompany loans, net	(408)	(11)	0
Return of capital contributions and dividends from subsidiaries	0	0	0
Capital contributions to subsidiaries	0	0	0
Collateral (delivered) received, net	(148)	(22)	19
Other, net	3	20	43
Net cash provided by (used in) investing activities - discontinued operations	(1,261)	(1,800)	(1,663)
Net cash used in investing activities	(2,827)	(3,690)	(4,056)
Cash Flows from Financing Activities:
Deposits received for investment contracts	5,061	5,891	5,298
Maturities and withdrawals from investment contracts	(5,372)	(5,412)	(4,587)
Proceeds from issuance of debt with maturities of more than three months	0	0
Repayment of debt with maturities of more than three months	0	0	0
Debt issuance costs	0	0	0
Proceeds of intercompany loans with maturities of more than three months	34
Intercompany loans with maturities of more than three months	(34)		(1)
Net proceeds from short-term loans to subsidiaries	56	(57)	105
Return of capital contributions and dividends to parent	(1,256)	(1,060)	(1,715)
Contributions of capital from parent	467	229	15
Borrowings of consolidated investment entities	967	126	1,373
Repayments of borrowings of consolidated investment entities	(804)	(455)	(479)
Contributions from (distributions to) participants in consolidated investment entities	449	51	662
Proceeds from issuance of common stock, net	0	0
Share-based compensation	0	0	0
Common stock acquired - Share repurchase	0	0	0
Dividends paid	0	0	0
Net cash provided by (used in) financing activities - discontinued operations	384	916	280
Net cash (used in) provided by financing activities	(48)	229	951
Net increase (decrease) in cash and cash equivalents	(1,181)	535	270
Cash and cash equivalents, beginning of period	2,652	2,117	1,847
Cash and cash equivalents, end of period	1,471	2,652	2,117
Less: Cash and cash equivalents of discontinued operations, end of period	498	815	696
Cash and cash equivalents of continuing operations, end of period	$ 973	$ 1,837	$ 1,421