Loans and Allowance for Credit Losses - Schedule of Activity In The Allowance For Loan Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 74	$ 67	$ 54
Provision for credit losses	88	10	15
Charge-offs		(3)	(2)
Ending balance	$ 122	$ 74	$ 67