Investment Securities - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Marketable Securities [Abstract]
Gains (losses) on available-for-sale securities	$ 0	$ 0	$ 0	$ 0
Available-for-sale, accrued interest, after allowance for credit loss	23,000,000		23,000,000		$ 22,000,000
Allowance for credit loss	0		0		0
Carrying amount of equity investments without a readily determinable fair value	73,000,000		73,000,000		$ 57,000,000
Unrealized gain (loss) for equity investments with readily determinable fair values	$ 1,000,000	$ 1,000,000	$ 7,000,000	$ (4,000,000)