Total Equity - Components of Period Changes in OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
After-tax Gain (Loss)
Total other comprehensive income (loss)	$ 868	$ (565)	$ 1,292
Foreign Currency Translation Adjustment Including Noncontrolling Interest
Pre-tax Gain (Loss)
OCI activity	74	6	(11)
Reclassified to earnings	(3)	0	0
Net OCI	71	6	(11)
Income Tax Benefit (Provision)
OCI activity	99	(3)	(79)
Reclassified to earnings	0	0	0
Net OCI	99	(3)	(79)
After-tax Gain (Loss)
OCI activity	173	3	(90)
Reclassified to earnings	(3)	0	0
Total other comprehensive income (loss)	170	3	(90)
Foreign Currency Translation Adjustment Attributable to Noncontrolling Interest
After-tax Gain (Loss)
OCI activity	68	11	24
Reclassified to earnings	0	0	0
Total other comprehensive income (loss)	68	11	24
Foreign Currency Translation Adjustment Attributable to Parent
After-tax Gain (Loss)
OCI activity	105	(8)	(114)
Reclassified to earnings	(3)	0	0
Total other comprehensive income (loss)	102	(8)	(114)
Change in Net Unrealized Gains (Losses) on AFS Securities Including Noncontrolling Interest
Pre-tax Gain (Loss)
OCI activity	2,194	1,588	(346)
Reclassified to earnings	(137)	(103)	(8)
Net OCI	2,057	1,485	(354)
Income Tax Benefit (Provision)
OCI activity	(508)	(373)	80
Reclassified to earnings	31	25	2
Net OCI	(477)	(348)	82
After-tax Gain (Loss)
OCI activity	1,686	1,215	(266)
Reclassified to earnings	(106)	(78)	(6)
Total other comprehensive income (loss)	1,580	1,137	(272)
Change in Net Unrealized Gains (Losses) on AFS Securities Attributable to Noncontrolling Interest
After-tax Gain (Loss)
OCI activity	0	0	0
Reclassified to earnings	0	0	0
Total other comprehensive income (loss)	0	0	0
Change in Net Unrealized Gains (Losses) on AFS Securities Attributable to Parent
After-tax Gain (Loss)
OCI activity	1,686	1,215	(266)
Reclassified to earnings	(106)	(78)	(6)
Total other comprehensive income (loss)	1,580	1,137	(272)
Pension and Other Including Noncontrolling Interest
Pre-tax Gain (Loss)
OCI activity	162	(98)	156
Reclassified to earnings	23	12	26
Net OCI	185	(86)	182
Income Tax Benefit (Provision)
OCI activity	(34)	25	(37)
Reclassified to earnings	(5)	(5)	(8)
Net OCI	(39)	20	(45)
After-tax Gain (Loss)
OCI activity	128	(73)	119
Reclassified to earnings	18	7	18
Total other comprehensive income (loss)	146	(66)	137
Pension and Other Attributable to Noncontrolling Interest
After-tax Gain (Loss)
OCI activity	0	0	0
Reclassified to earnings	0	0	0
Total other comprehensive income (loss)	0	0	0
Pension and Other Attributable to Parent
After-tax Gain (Loss)
OCI activity	128	(73)	119
Reclassified to earnings	18	7	18
Total other comprehensive income (loss)	146	(66)	137
Change in Net DVA Including Noncontrolling Interest
Pre-tax Gain (Loss)
OCI activity	(1,385)	(2,181)	1,947
Reclassified to earnings	26	11	56
Net OCI	(1,359)	(2,170)	2,003
Income Tax Benefit (Provision)
OCI activity	337	533	(472)
Reclassified to earnings	(6)	(2)	(14)
Net OCI	331	531	(486)
After-tax Gain (Loss)
OCI activity	(1,048)	(1,648)	1,475
Reclassified to earnings	20	9	42
Total other comprehensive income (loss)	(1,028)	(1,639)	1,517
Change in Net DVA Attributable to Noncontrolling Interest
After-tax Gain (Loss)
OCI activity	(26)	(80)	63
Reclassified to earnings	0	0	0
Total other comprehensive income (loss)	(26)	(80)	63
Change in Net DVA Attributable to Parent
After-tax Gain (Loss)
OCI activity	(1,022)	(1,568)	1,412
Reclassified to earnings	20	9	42
Total other comprehensive income (loss)	$ (1,002)	$ (1,559)	$ 1,454