Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	$ 265	$ 292	$ 265	$ 266
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	(2)	(15)	9	(10)
Net investment income	0	0	0	0
Purchases	7	29	14	53
Sales	(4)	(1)	(23)	(14)
Issuances	0	0	0	0
Settlements	0	0	0	(13)
Foreign currency translation	3	3	6	18
Other	0	0	(1)	0
Transfers into Level 3	0	0	0	7
Transfers out of Level 3	0	(7)	(1)	(7)
Fair Value, end of period	273	301	273	301
Equity securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	4	0	4	1
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	3	0	3	0
Equity securities | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Notes Issued by Consolidated VIEs
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(1,854)	(2,946)	(1,839)	(8,597)
Total gains (losses) (realized/unrealized):
Net investment income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Foreign currency translation	0	0	0	0
Other	0	940	0	6,509
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(1,853)	(2,094)	(1,853)	(2,094)
Notes Issued by Consolidated VIEs | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	1	(98)	(14)	3
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	1	(98)	(14)	3
Notes Issued by Consolidated VIEs | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	10	0	(9)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	10	0	(9)
Notes Issued by Consolidated VIEs | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Fixed maturities | U.S. Treasury securities and obligations of U.S. government authorities and agencies
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	10		0
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	0		0
Net investment income	0		0
Purchases	22		22
Sales	0		0
Issuances	0		0
Settlements	0		0
Foreign currency translation	0		0
Other	0		10
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Fair Value, end of period	32		32
Fixed maturities | U.S. Treasury securities and obligations of U.S. government authorities and agencies | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Fixed maturities | U.S. states
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	5	6	5	6
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	0	0	0	0
Net investment income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	(1)	0	(1)
Foreign currency translation	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	5	5	5	5
Fixed maturities | U.S. states | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Fixed maturities | Foreign government bonds
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	136	122	124	123
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	2	0	2	1
Net investment income	0	0	0	0
Purchases	(1)	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Foreign currency translation	(4)	2	1	0
Other	0	0	0	0
Transfers into Level 3	11	0	18	0
Transfers out of Level 3	(1)	0	(2)	0
Fair Value, end of period	143	124	143	124
Fixed maturities | Foreign government bonds | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Fixed maturities | Corporate securities
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	2,111	2,074	2,173	1,222
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	(16)	164	(3)	20
Net investment income	2	2	11	4
Purchases	88	130	122	191
Sales	(3)	(2)	(144)	(6)
Issuances	0	0	0	0
Settlements	(388)	(52)	(447)	(122)
Foreign currency translation	0	12	9	25
Other	0	0	(10)	0
Transfers into Level 3	28	43	126	1,121
Transfers out of Level 3	(143)	(113)	(202)	(113)
Fair Value, end of period	1,662	2,254	1,662	2,254
Fixed maturities | Corporate securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(17)	(4)	27	(88)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(31)	2	(40)	(81)
Fixed maturities | Structured securities
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	5,911	4,772	4,555	4,269
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	(13)	2	(13)	(39)
Net investment income	2	4	5	8
Purchases	1,659	168	2,441	352
Sales	(385)	(9)	(395)	(43)
Issuances	0	0	0	0
Settlements	(994)	(177)	(1,414)	(220)
Foreign currency translation	13	11	25	61
Other	0	25	(1)	114
Transfers into Level 3	998	354	2,645	1,204
Transfers out of Level 3	(504)	(1,884)	(1,163)	(2,441)
Fair Value, end of period	6,744	3,267	6,744	3,267
Fixed maturities | Structured securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	57	1	59	2
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading account assets | Foreign government bonds
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	227	36	227	34
Total gains (losses) (realized/unrealized):
Net investment income	2	0	3	0
Purchases	0	4	0	6
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(2)	(2)	(2)	(2)
Foreign currency translation	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	228	38	228	38
Trading account assets | Foreign government bonds | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading account assets | Foreign government bonds | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	1	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	2	0	0	0
Trading account assets | Corporate securities
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	217	228	188	203
Total gains (losses) (realized/unrealized):
Net investment income	1	1	1	1
Purchases	31	5	73	8
Sales	(3)	0	(6)	0
Issuances	0	0	0	0
Settlements	(55)	(20)	(85)	(35)
Foreign currency translation	0	0	0	0
Other	3	0	3	(15)
Transfers into Level 3	1	40	22	127
Transfers out of Level 3	0	(36)	(4)	(61)
Fair Value, end of period	200	216	200	216
Trading account assets | Corporate securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading account assets | Corporate securities | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	5	(2)	8	(12)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	3	(3)	5	(13)
Trading account assets | Structured securities
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	739	616	332	603
Total gains (losses) (realized/unrealized):
Net investment income	1	1	1	1
Purchases	41	8	235	26
Sales	(13)	1	(13)	0
Issuances	0	0	0	0
Settlements	(115)	(4)	(133)	(5)
Foreign currency translation	2	(1)	3	(1)
Other	0	4	1	19
Transfers into Level 3	166	64	425	179
Transfers out of Level 3	(156)	(382)	(186)	(510)
Fair Value, end of period	666	310	666	310
Trading account assets | Structured securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading account assets | Structured securities | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	1	3	1	(2)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	1	2	2	(1)
Trading account assets | Equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	546	581	487	589
Total gains (losses) (realized/unrealized):
Net investment income	0	0	0	0
Purchases	3	4	18	5
Sales	(2)	(1)	(11)	(12)
Issuances	0	0	0	0
Settlements	(1)	(2)	(7)	(77)
Foreign currency translation	2	13	8	42
Other	(4)	(3)	(3)	15
Transfers into Level 3	0	0	31	28
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	543	585	543	585
Trading account assets | Equity securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading account assets | Equity securities | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	(1)	(7)	20	(5)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	12	(6)	33	(4)
Trading account assets | All other activity
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1	1	1	5
Total gains (losses) (realized/unrealized):
Net investment income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Foreign currency translation	0	0	0	0
Other	0	0	0	(4)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	1	2	1	2
Trading account assets | All other activity | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading account assets | All other activity | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	1	0	1
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	1
Other long-term investments
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	78	19	7	49
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	0	0	0	0
Net investment income	0	(1)	0	(1)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Foreign currency translation	0	0	0	0
Other	(1)	(3)	70	(33)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	76	14	76	14
Other long-term investments | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(1)	(1)	(1)	(1)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(2)	(2)	(5)	(1)
Other long-term investments | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Short-term investments
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1		1
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	0		0
Net investment income	0		0
Purchases	0		0
Sales	0		0
Issuances	0		0
Settlements	0		0
Foreign currency translation	0		0
Other	0		0
Transfers into Level 3	1		1
Transfers out of Level 3	0		0
Fair Value, end of period	2		2
Short-term investments | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Short-term investments | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Cash equivalents
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	6		0
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	0		0
Net investment income	0		2
Purchases	0		0
Sales	0		0
Issuances	0		0
Settlements	(6)		(6)
Foreign currency translation	0		0
Other	(4)		0
Transfers into Level 3	4		4
Transfers out of Level 3	0		0
Fair Value, end of period	0		0
Cash equivalents | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Cash equivalents | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Other assets
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	36	0	7
Total gains (losses) (realized/unrealized):
Included in other comprehensive income (loss)	0	0	0	0
Net investment income	0	0	0	0
Purchases	9	5	17	9
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Foreign currency translation	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	39	62	39	62
Other assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	30	21	22	46
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	30	24	22	46
Other assets | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Separate accounts assets
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1,975	2,168	1,849	1,995
Total gains (losses) (realized/unrealized):
Net investment income	1	7	1	13
Purchases	383	96	538	258
Sales	(68)	(13)	(72)	(73)
Issuances	0	0	0	0
Settlements	(175)	(55)	(381)	(88)
Foreign currency translation	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	63	76	254	273
Transfers out of Level 3	(94)	(166)	(128)	(254)
Fair Value, end of period	2,107	2,128	2,107	2,128
Separate accounts assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	1
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Separate accounts assets | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Separate accounts assets | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	22	15	46	3
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	16	9	40	(3)
Future policy benefits
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(7,640)	(11,069)	(8,238)	(8,434)
Total gains (losses) (realized/unrealized):
Net investment income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	(279)	(261)	(554)	(515)
Settlements	0	0	0	0
Foreign currency translation	0	0	(2)	(1)
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(10,031)	(13,328)	(10,031)	(13,328)
Future policy benefits | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(2,112)	(1,998)	(1,237)	(4,378)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(2,173)	(2,071)	(1,365)	(4,497)
Future policy benefits | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Future policy benefits | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Other liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(27)	(2)	(22)	(2)
Total gains (losses) (realized/unrealized):
Net investment income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(1)	0	0	0
Foreign currency translation	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(34)	(2)	(34)	(2)
Other liabilities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(6)	0	(12)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(4)	0	(12)	0
Other liabilities | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Other liabilities | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	$ 0	$ 0	$ 0	$ 0