Loans and Allowance for Loan Losses - Sale of Loans Held-For-Investment (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Derecognized	$ 89
Allowance for Loan Losses Derecognized	0
Proceeds from Sale	91
Gain (Loss) on Sales	2
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Derecognized	89
Allowance for Loan Losses Derecognized	0
Proceeds from Sale	91
Gain (Loss) on Sales	$ 2