Total Equity - Components of Period Changes in OCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
After-tax Gain (Loss)
Net OCI	$ 455	$ (988)	$ 674	$ (498)
Foreign Currency Translation Adjustment Including Noncontrolling Interest
Pre-tax Gain (Loss)
OCI activity	(26)	(44)	2	(52)
Reclassified to earnings	0	0	0	0
Net OCI	(26)	(44)	2	(52)
Income Tax Benefit (Provision)
OCI activity	(73)	(35)	(58)	(102)
Reclassified to earnings	0	0	0	0
Net OCI	(73)	(35)	(58)	(102)
After-tax Gain (Loss)
OCI activity	(99)	(79)	(56)	(154)
Reclassified to earnings	0	0	0	0
Net OCI	(99)	(79)	(56)	(154)
Foreign Currency Translation Adjustment Attributable to Noncontrolling Interest
After-tax Gain (Loss)
OCI activity	(3)	(25)	16	(11)
Reclassified to earnings	0	0	0	0
Net OCI	(3)	(25)	16	(11)
Foreign Currency Translation Adjustment Attributable to Parent
After-tax Gain (Loss)
OCI activity	(96)	(54)	(72)	(143)
Reclassified to earnings	0	0	0	0
Net OCI	(96)	(54)	(72)	(143)
Change in Net Unrealized Gains (Losses) on AFS Securities Including Noncontrolling Interest
Pre-tax Gain (Loss)
OCI activity	307	(219)	1,726	(916)
Reclassified to earnings	(26)	(5)	(89)	(8)
Net OCI	281	(224)	1,637	(924)
Income Tax Benefit (Provision)
OCI activity	(73)	51	(406)	215
Reclassified to earnings	6	2	21	2
Net OCI	(67)	53	(385)	217
After-tax Gain (Loss)
OCI activity	234	(168)	1,320	(701)
Reclassified to earnings	(20)	(3)	(68)	(6)
Net OCI	214	(171)	1,252	(707)
Change in Net Unrealized Gains (Losses) on AFS Securities Attributable to Noncontrolling Interest
After-tax Gain (Loss)
OCI activity	0	0	0	0
Reclassified to earnings	0	0	0	0
Net OCI	0	0	0	0
Change in Net Unrealized Gains (Losses) on AFS Securities Attributable to Parent
After-tax Gain (Loss)
OCI activity	234	(168)	1,320	(701)
Reclassified to earnings	(20)	(3)	(68)	(6)
Net OCI	214	(171)	1,252	(707)
Pension, Postretirement and Other Including Noncontrolling Interest
Pre-tax Gain (Loss)
OCI activity	0	0	0	2
Reclassified to earnings	4	7	10	19
Net OCI	4	7	10	21
Income Tax Benefit (Provision)
OCI activity	0	0	(1)	0
Reclassified to earnings	(1)	(2)	(2)	(5)
Net OCI	(1)	(2)	(3)	(5)
After-tax Gain (Loss)
OCI activity	0	0	(1)	2
Reclassified to earnings	3	5	8	14
Net OCI	3	5	7	16
Pension, Postretirement and Other Attributable to Noncontrolling Interest
After-tax Gain (Loss)
OCI activity	0	0	0	0
Reclassified to earnings	0	0	0	0
Net OCI	0	0	0	0
Pension, Postretirement and Other Attributable to Parent
After-tax Gain (Loss)
OCI activity	0	0	(1)	2
Reclassified to earnings	3	5	8	14
Net OCI	3	5	7	16
Change in Net DVA Including Noncontrolling Interest
Pre-tax Gain (Loss)
OCI activity	441	(1,018)	(713)	403
Reclassified to earnings	2	36	9	54
Net OCI	443	(982)	(704)	457
Income Tax Benefit (Provision)
OCI activity	(106)	248	177	(97)
Reclassified to earnings	0	(9)	(2)	(13)
Net OCI	(106)	239	175	(110)
After-tax Gain (Loss)
OCI activity	335	(770)	(536)	306
Reclassified to earnings	2	27	7	41
Net OCI	337	(743)	(529)	347
Change in Net DVA Attributable to Noncontrolling Interest
After-tax Gain (Loss)
OCI activity	5	(34)	(36)	15
Reclassified to earnings	0	0	0	0
Net OCI	5	(34)	(36)	15
Change in Net DVA Attributable to Parent
After-tax Gain (Loss)
OCI activity	330	(736)	(500)	291
Reclassified to earnings	2	27	7	41
Net OCI	$ 332	$ (709)	$ (493)	$ 332