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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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		6 Months Ended
	Jun. 30, 2020 USD ($) loan	Jun. 30, 2019 USD ($) loan	Jun. 30, 2020 USD ($) loan	Jun. 30, 2019 USD ($) loan	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Troubled Debt Restructurings
TDRs	$ 50		$ 50			$ 48
Allowance for loan loss	229	$ 110	229	$ 110	$ 132	107	$ 127	$ 128
TDR loans under fair value option	$ 2		$ 2			2
Number of Accounts \| loan	1	2	9	6
Pre-Modification Unpaid Principal Balance	$ 5	$ 0	$ 6	$ 1
Post-Modification Unpaid Principal Balance	5	0	6	1
Troubled debt restructurings
Troubled Debt Restructurings
Allowance for loan loss	4		4			8
Performing
Troubled Debt Restructurings
TDRs	40		40			38
Nonperforming
Troubled Debt Restructurings
TDRs	10		10			10
Consumer loans \| Residential First Mortgage
Troubled Debt Restructurings
TDRs	28		28			28
Allowance for loan loss	60	26	$ 60	$ 26	46	22	35	38
Number of Accounts \| loan			5	2
Pre-Modification Unpaid Principal Balance			$ 1	$ 0
Post-Modification Unpaid Principal Balance			1	0
Consumer loans \| Residential First Mortgage \| Performing
Troubled Debt Restructurings
TDRs	20		20			20
Consumer loans \| Residential First Mortgage \| Nonperforming
Troubled Debt Restructurings
TDRs	8		8			8
Consumer loans \| Home equity
Troubled Debt Restructurings
TDRs	17		17			20
Allowance for loan loss	28	$ 16	$ 28	$ 16	$ 23	14	$ 16	$ 15
Number of Accounts \| loan		2	2	4
Pre-Modification Unpaid Principal Balance		$ 0	$ 0	$ 1
Post-Modification Unpaid Principal Balance		$ 0	0	$ 1
Consumer loans \| Home equity \| Performing
Troubled Debt Restructurings
TDRs	15		15			18
Consumer loans \| Home equity \| Nonperforming
Troubled Debt Restructurings
TDRs	2		2			$ 2
Consumer loans \| Commercial real estate
Troubled Debt Restructurings
TDRs	$ 5		$ 5
Number of Accounts \| loan	1		1
Pre-Modification Unpaid Principal Balance	$ 5		$ 5
Post-Modification Unpaid Principal Balance	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
Consumer loans \| Consumer
Troubled Debt Restructurings
Number of Accounts \| loan			1
Pre-Modification Unpaid Principal Balance			$ 0
Post-Modification Unpaid Principal Balance			$ 0