Fair Value (Fair Value, by Balance Sheet Grouping) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	$ 1,126	$ 1,253
Loans held-for-sale, net	409	406
Finance receivables and loans, net	109,091	115,251
Deposit liabilities	139,104	137,036
Short-term borrowings	0	2,136
Long-term debt	16,896	22,006
Carrying value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,126	1,253
Loans held-for-sale, net	312	315
Finance receivables and loans, net	109,083	115,243
FHLB/FRB stock	688	725
Deposit liabilities	47,253	55,210
Short-term borrowings		2,136
Long-term debt	16,896	22,006
Estimated fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,173	1,331
Loans held-for-sale, net	312	315
Finance receivables and loans, net	116,169	122,156
FHLB/FRB stock	688	725
Deposit liabilities	47,675	55,932
Short-term borrowings		2,136
Long-term debt	19,734	25,471
Estimated fair value \| Fair value, inputs, level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	0	0
Loans held-for-sale, net	0	0
Finance receivables and loans, net	0	0
FHLB/FRB stock	0	0
Deposit liabilities	0	0
Short-term borrowings		0
Long-term debt	0	0
Estimated fair value \| Fair value, inputs, level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,173	1,331
Loans held-for-sale, net	0	0
Finance receivables and loans, net	0	0
FHLB/FRB stock	688	725
Deposit liabilities	0	0
Short-term borrowings		0
Long-term debt	14,250	19,161
Estimated fair value \| Fair value, inputs, level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	0	0
Loans held-for-sale, net	312	315
Finance receivables and loans, net	116,169	122,156
FHLB/FRB stock	0	0
Deposit liabilities	47,675	55,932
Short-term borrowings		2,136
Long-term debt	$ 5,484	$ 6,310

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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