Equity Activity in OCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity [Abstract]
Net income	$ 4,457	$ 3,200	$ 8,718	$ 5,973
Other comprehensive income (loss), net of tax effect:
Changes in net unrealized gains (losses) on AFS securities (net of tax of $1 and $6, respectively, for the three months ended and net of tax of $14 and $11, respectively, for the six months ended)	4	11	(53)	20
Reclassification adjustments for gains on AFS securities and other-than-temporary impairment (“OTTI”) recognized in net income (net of tax of $0 and $50, respectively, for the three months ended and $70 and $51, respectively, for the six months ended)	0	(92)	(263)	(93)
Other	(2)	(2)	(5)	(4)
Total other comprehensive income (loss)	2	(83)	(321)	(77)
Total comprehensive income	4,459	3,117	8,397	5,896
Other Comprehensive Income (Loss), Tax, Parenthetical Disclosures [Abstract]
Changes in net unrealized gains (losses) on AFS securities (net of tax of $1 and $6, respectively, for the three months ended and net of tax of $14 and $11, respectively, for the six months ended )	1	6	(14)	11
Reclassification adjustments for gains on AFS securities and other-than-temporary impairment (“OTTI”) recognized in net income (net of tax of $0 and $50, respectively, for the three months ended and $70 and $51, respectively, for the six months ended)	$ 0	$ (50)	$ (70)	$ (51)