The TDR loans held-for-investment carried under the fair value option method.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Number of financing receivables that have been modified by troubled debt restructurings.

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Amount, after troubled debt restructuring, of modified financing receivable.

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Amount, before troubled debt restructuring, of financing receivable to be modified.

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Amount of financing receivable modified as troubled debt restructuring.

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Loans Held-for-Investment - Summary of TDRs by Type and Performing Status and Newly Modified TDRs (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) loan	Sep. 30, 2019 USD ($) loan	Sep. 30, 2020 USD ($) loan	Sep. 30, 2019 USD ($) loan	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Troubled Debt Restructurings
TDRs	$ 48		$ 48			$ 48
Allowance for loan loss	255	$ 110	255	$ 110	$ 229	107	$ 110	$ 128
TDR loans under fair value option	$ 2		$ 2			2
Number of Accounts \| loan	3	4	12	10
Pre-Modification Unpaid Principal Balance	$ 0	$ 1	$ 6	$ 2
Post-Modification Unpaid Principal Balance	0	$ 1	6	$ 2
Troubled debt restructurings
Troubled Debt Restructurings
Allowance for loan loss	5		5			8
Performing
Troubled Debt Restructurings
TDRs	39		39			38
Nonperforming
Troubled Debt Restructurings
TDRs	$ 9		$ 9			10
Residential first mortgage loans
Troubled Debt Restructurings
Number of Accounts \| loan	1	4	6	6
Pre-Modification Unpaid Principal Balance	$ 0	$ 1	$ 1	$ 1
Post-Modification Unpaid Principal Balance	$ 0	1	$ 1	$ 1
Home equity
Troubled Debt Restructurings
Number of Accounts \| loan	1		3	4
Pre-Modification Unpaid Principal Balance	$ 0		$ 0	$ 1
Post-Modification Unpaid Principal Balance	$ 0		$ 0	1
Commercial real estate
Troubled Debt Restructurings
Number of Accounts \| loan			1
Pre-Modification Unpaid Principal Balance			$ 5
Post-Modification Unpaid Principal Balance			$ 5
Consumer
Troubled Debt Restructurings
Number of Accounts \| loan	1		2
Pre-Modification Unpaid Principal Balance	$ 0		$ 0
Post-Modification Unpaid Principal Balance	0		0
Consumer loans \| Residential first mortgage loans
Troubled Debt Restructurings
TDRs	27		27			28
Allowance for loan loss	52	28	52	28	60	22	26	38
Consumer loans \| Residential first mortgage loans \| Performing
Troubled Debt Restructurings
TDRs	20		20			20
Consumer loans \| Residential first mortgage loans \| Nonperforming
Troubled Debt Restructurings
TDRs	7		7			8
Consumer loans \| Home equity
Troubled Debt Restructurings
TDRs	16		16			20
Allowance for loan loss	29	$ 16	29	$ 16	$ 28	14	$ 16	$ 15
Consumer loans \| Home equity \| Performing
Troubled Debt Restructurings
TDRs	14		14			18
Consumer loans \| Home equity \| Nonperforming
Troubled Debt Restructurings
TDRs	2		2			$ 2
Consumer loans \| Commercial real estate
Troubled Debt Restructurings
TDRs	5		5
Consumer loans \| Commercial real estate \| Performing
Troubled Debt Restructurings
TDRs	5		5
Consumer loans \| Commercial real estate \| Nonperforming
Troubled Debt Restructurings
TDRs	$ 0		$ 0