Investment Securities (Maturities of Securities Available for Sale and Held to Maturity) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Available for sale securities, fair value
Within 1 year	$ 8,846
After 1 year through 5 years	40,165
After 5 years through 10 years	63,843
After 10 years	168,362
Fair Value	281,216	$ 61,422
Available for sale securities, amortized cost
Within 1 year	25,912
After 1 year through 5 years	36,951
After 5 years through 10 years	57,237
After 10 years	153,647
Amortized Cost	273,747	61,155
U.S. agency mortgage-backed securities [Member]
Available for sale securities, fair value
Within 1 year	1,090
After 1 year through 5 years	22,122
After 5 years through 10 years	55,851
After 10 years	158,024
Fair Value	237,087	46,155
Available for sale securities, amortized cost
Amortized Cost	230,102	45,964
Asset-backed securities [Member]
Available for sale securities, fair value
Within 1 year	60
After 1 year through 5 years	8,183
After 5 years through 10 years	5,700
After 10 years	8,176
Fair Value	22,119	4,987
Available for sale securities, amortized cost
Amortized Cost	22,234	4,970
Corporate debt securities [Member]
Available for sale securities, fair value
Within 1 year	2,750
After 1 year through 5 years	8,628
After 5 years through 10 years	1,661
After 10 years	0
Fair Value	13,039	5,484
Available for sale securities, amortized cost
Amortized Cost	12,653	5,427
U.S. Treasury securities [Member]
Available for sale securities, fair value
Within 1 year	3,943
After 1 year through 5 years	828
After 5 years through 10 years	0
After 10 years	0
Fair Value	4,771	3,384
Available for sale securities, amortized cost
Amortized Cost	4,733	3,387
U.S. state and municipal securities [Member]
Available for sale securities, fair value
Within 1 year	0
After 1 year through 5 years	103
After 5 years through 10 years	631
After 10 years	886
Fair Value	1,620
Available for sale securities, amortized cost
Amortized Cost	1,489
Non-agency commercial mortgage-backed securities [Member]
Available for sale securities, fair value
Within 1 year	0
After 1 year through 5 years	0
After 5 years through 10 years	0
After 10 years	1,254
Fair Value	1,254	13
Available for sale securities, amortized cost
Amortized Cost	1,214	13
Certificates of deposit [Member]
Available for sale securities, fair value
Within 1 year	803
After 1 year through 5 years	0
After 5 years through 10 years	0
After 10 years	0
Fair Value	803	1,004
Available for sale securities, amortized cost
Amortized Cost	800	1,000
Commercial paper [Member]
Available for sale securities, fair value
Within 1 year	200
After 1 year through 5 years	0
After 5 years through 10 years	0
After 10 years	0
Fair Value	200	395
Available for sale securities, amortized cost
Amortized Cost	200	$ 394
Foreign government agency securities [Member]
Available for sale securities, fair value
Within 1 year	0
After 1 year through 5 years	301
After 5 years through 10 years	0
After 10 years	0
Fair Value	301
Available for sale securities, amortized cost
Amortized Cost	300
Other [Member]
Available for sale securities, fair value
Within 1 year	0
After 1 year through 5 years	0
After 5 years through 10 years	0
After 10 years	22
Fair Value	22
Available for sale securities, amortized cost
Amortized Cost	$ 22

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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