Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	$ 671	$ 795
Purchases	79	66
Sales	(52)	(100)
Issuances	0	0
Settlements	(85)	(82)
Other	1	18
Transfers into Level 3	1	5
Transfers out of Level 3	(24)	(25)
Fair Value, end of period	633	671	$ 795
Total gains (losses) (realized/unrealized):
Included in earnings	42	(6)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	34	(19)
Equity securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	2
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	(4)
Equity securities | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	42	(6)	25
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	34	(19)	38
Equity securities | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Equity securities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	17
Equity securities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Assets supporting experience-rated contractholder liabilities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Assets supporting experience-rated contractholder liabilities | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	(4)	(39)	(35)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(5)	(38)	(34)
Assets supporting experience-rated contractholder liabilities | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Assets supporting experience-rated contractholder liabilities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Assets supporting experience-rated contractholder liabilities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	9	8	8
Assets supporting experience-rated contractholder liabilities | Foreign government bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	225	223
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(5)	(5)
Other	(196)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	24	225	223
Total gains (losses) (realized/unrealized):
Included in earnings	0	7
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	1
Assets supporting experience-rated contractholder liabilities | Corporate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	444	462
Purchases	146	147
Sales	0	0
Issuances	0	0
Settlements	(189)	(179)
Other	196	0
Transfers into Level 3	46	72
Transfers out of Level 3	(10)	(23)
Fair Value, end of period	637	444	462
Total gains (losses) (realized/unrealized):
Included in earnings	4	(35)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(6)	(37)
Assets supporting experience-rated contractholder liabilities | Structured securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	149	723
Purchases	29	97
Sales	0	0
Issuances	0	0
Settlements	(35)	(165)
Other	0	0
Transfers into Level 3	0	33
Transfers out of Level 3	(74)	(538)
Fair Value, end of period	69	149	723
Total gains (losses) (realized/unrealized):
Included in earnings	0	(1)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	(2)
Assets supporting experience-rated contractholder liabilities | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1	4
Purchases	0	0
Sales	(2)	(3)
Issuances	0	0
Settlements	0	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	0	1	4
Total gains (losses) (realized/unrealized):
Included in earnings	1	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	1	0
Assets supporting experience-rated contractholder liabilities | All other activity
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	7
Purchases	8	91
Sales	0	(3)
Issuances	0	0
Settlements	(8)	(93)
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	0	0	7
Total gains (losses) (realized/unrealized):
Included in earnings	0	(2)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Other invested assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	263	137
Purchases	341	136
Sales	0	(18)
Issuances	0	0
Settlements	(42)	0
Other	(6)	4
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	567	263	137
Total gains (losses) (realized/unrealized):
Included in earnings	11	4
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1)	3
Other invested assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(1)	4	1
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1)	2	0
Other invested assets | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	12	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	1	0
Other invested assets | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Other invested assets | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Other invested assets | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Short-term investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	89	8
Purchases	597	287
Sales	0	0
Issuances	0	0
Settlements	(526)	(201)
Other	(5)	(5)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	155	89	8
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	(1)
Short-term investments | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	(1)	0
Short-term investments | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Short-term investments | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Short-term investments | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Short-term investments | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Cash equivalents
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	77	0
Purchases	131	95
Sales	0	(2)
Issuances	0	0
Settlements	(77)	(15)
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	131	77	0
Total gains (losses) (realized/unrealized):
Included in earnings	0	(1)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Cash equivalents | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	(1)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Cash equivalents | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Cash equivalents | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Cash equivalents | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Cash equivalents | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	2
Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	25	13
Purchases	44	46
Sales	0	0
Issuances	0	0
Settlements	0	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	113	25	13
Total gains (losses) (realized/unrealized):
Included in earnings	44	(34)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	44	(34)
Other assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	44	(34)	(20)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	44	(34)	(21)
Other assets | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Other assets | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Other assets | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Other assets | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Separate accounts assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1,534	2,122
Purchases	346	587
Sales	(111)	(36)
Issuances	0	0
Settlements	(144)	(358)
Other	0	0
Transfers into Level 3	55	287
Transfers out of Level 3	(147)	(1,004)
Fair Value, end of period	1,717	1,534	2,122
Total gains (losses) (realized/unrealized):
Included in earnings	184	(64)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	170	(52)
Separate accounts assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Separate accounts assets | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Separate accounts assets | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	180	(66)	81
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	170	(52)	78
Separate accounts assets | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Separate accounts assets | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	4	2	2
Future policy benefits
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(8,926)	(8,720)
Purchases	0	0
Sales	0	0
Issuances	(1,221)	(1,153)
Settlements	0	0
Other	1	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(12,831)	(8,926)	(8,720)
Total gains (losses) (realized/unrealized):
Included in earnings	(2,685)	947
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(2,999)	611
Future policy benefits | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(2,685)	947	637
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(2,999)	611	372
Future policy benefits | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Future policy benefits | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Future policy benefits | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Future policy benefits | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Policyholders’ account balances
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(56)	(47)
Purchases	0	0
Sales	0	0
Issuances	(324)	(39)
Settlements	0	0
Other	(3)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(1,316)	(56)	(47)
Total gains (losses) (realized/unrealized):
Included in earnings	(933)	30
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(917)	30
Policyholders’ account balances | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(933)	30	(31)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(917)	30	(31)
Policyholders’ account balances | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Policyholders’ account balances | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Policyholders’ account balances | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Policyholders’ account balances | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Other liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	(3)
Purchases	0	0
Sales	0	0
Issuances	(100)	0
Settlements	0	0
Other	0	1
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(105)	0	(3)
Total gains (losses) (realized/unrealized):
Included in earnings	(5)	2
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(5)	3
Other liabilities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	2	(6)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	3	(6)
Other liabilities | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	(5)	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(5)	0	0
Other liabilities | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Other liabilities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Other liabilities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Notes issued by consolidated VIEs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(595)	(1,196)
Purchases	0	0
Sales	0	0
Issuances	(858)	0
Settlements	638	0
Other	0	587
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(800)	(595)	(1,196)
Total gains (losses) (realized/unrealized):
Included in earnings	15	14
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	15	14
Notes issued by consolidated VIEs | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	15	14	(4)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	15	14	(4)
Notes issued by consolidated VIEs | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Notes issued by consolidated VIEs | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Notes issued by consolidated VIEs | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Notes issued by consolidated VIEs | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Available-for-sale | Fixed Maturities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(67)	(29)	(23)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(98)	(60)	(154)
Available-for-sale | Fixed Maturities | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Available-for-sale | Fixed Maturities | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Available-for-sale | Fixed Maturities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	86	(141)	(12)
Available-for-sale | Fixed Maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	18	17	26
Available-for-sale | Fixed Maturities | U.S. government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	81	52
Purchases	24	29
Sales	0	0
Issuances	0	0
Settlements	0	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	105	81	52
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Available-for-sale | Fixed Maturities | U.S. states
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	5	5
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(1)	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	4	5	5
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Available-for-sale | Fixed Maturities | Foreign government bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	125	148
Purchases	0	5
Sales	0	0
Issuances	0	0
Settlements	0	0
Other	(1)	(9)
Transfers into Level 3	10	20
Transfers out of Level 3	(112)	(36)
Fair Value, end of period	22	125	148
Total gains (losses) (realized/unrealized):
Included in earnings	0	(3)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(2)	0
Available-for-sale | Fixed Maturities | Corporate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	2,685	2,776
Purchases	1,462	919
Sales	(47)	(25)
Issuances	0	0
Settlements	(1,137)	(991)
Other	10	(15)
Transfers into Level 3	353	485
Transfers out of Level 3	(87)	(354)
Fair Value, end of period	3,236	2,685	2,776
Total gains (losses) (realized/unrealized):
Included in earnings	(3)	(110)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(96)	(60)
Available-for-sale | Fixed Maturities | Structured securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1,339	6,715
Purchases	952	2,808
Sales	(67)	(612)
Issuances	0	0
Settlements	(507)	(1,589)
Other	(4)	1
Transfers into Level 3	755	1,212
Transfers out of Level 3	(1,560)	(7,156)
Fair Value, end of period	948	1,339	6,715
Total gains (losses) (realized/unrealized):
Included in earnings	40	(40)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Trading | Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	206	156
Purchases	105	96
Sales	(31)	(59)
Issuances	0	0
Settlements	0	(3)
Other	(7)	3
Transfers into Level 3	41	13
Transfers out of Level 3	(1)	(6)
Fair Value, end of period	287	206	156
Total gains (losses) (realized/unrealized):
Included in earnings	(26)	6
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(27)	8
Trading | Fixed Maturities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Trading | Fixed Maturities | Other Income
Total gains (losses) (realized/unrealized):
Included in earnings	(27)	5	(2)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(27)	8	(1)
Trading | Fixed Maturities | Interest credited to policyholders' account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Trading | Fixed Maturities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Trading | Fixed Maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	$ 1	$ 1	$ 1