Investment Securities - Amortized Cost and Fair Value of Available-for-Sale Debt and Held-to-Maturity Securities (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Available-for-Sale Debt and Other, Amortized Cost
Less than 1 year		$ 55
1-5 years		14,598
5-10 years		14,644
Over 10 years		5,935
Other securities		548
Amortized Cost		35,780	$ 34,966
Available-for-Sale Debt and Other, Fair Value
Less than 1 year		57
1-5 years		15,565
5-10 years		16,051
Over 10 years		6,378
Other securities		548
Fair Value	[1]	38,599	36,028
Held-to-Maturity, Amortized Cost
Less than 1 year		4
1-5 years		10
5-10 years		0
Over 10 years		2
Other securities		0
Amortized Cost	[2]	16	17
Held-to-Maturity, Fair Value
Less than 1 year		4
1-5 years		10
5-10 years		0
Over 10 years		2
Other securities		0
Fair Value		$ 16	$ 17

[1] Amortized cost of $35,780 and $34,966 at June 30, 2020 and December 31, 2019, respectively.

[2] Fair value of $16 and $17 at June 30, 2020 and December 31, 2019, respectively.