Deposits and Borrowings - Long-Term Debt (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total long-term debt	$ 50,023	$ 49,503
Total short-term borrowings and long-term debt	$ 50,358	58,905
Securitized debt obligations
Debt Instrument [Line Items]
Weighted average interest rate	2.34%
Carrying value	$ 19,273	18,307
Total senior and subordinated notes
Debt Instrument [Line Items]
Carrying value	$ 30,645	30,826
Senior notes \| Total unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	3.17%
Carrying value	$ 26,020	26,283
Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	3.13%
Carrying value	$ 23,027	23,290
Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	3.48%
Carrying value	$ 2,993	2,993
Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Weighted average interest rate	4.09%
Carrying value	$ 4,625	4,543
FHLB advances
Debt Instrument [Line Items]
Weighted average interest rate	4.95%
Carrying value	$ 1	251
Other borrowings
Debt Instrument [Line Items]
Weighted average interest rate	4.95%
Carrying value	$ 104	119
Total other long-term borrowings
Debt Instrument [Line Items]
Carrying value	$ 105	$ 370
Minimum \| Securitized debt obligations
Debt Instrument [Line Items]
Stated interest rates	1.33%
Minimum \| Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	1.85%
Minimum \| Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	3.10%
Minimum \| Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Stated interest rates	3.38%
Minimum \| FHLB advances
Debt Instrument [Line Items]
Stated interest rates	4.46%
Minimum \| Other borrowings
Debt Instrument [Line Items]
Stated interest rates	1.00%
Maximum \| Securitized debt obligations
Debt Instrument [Line Items]
Stated interest rates	3.34%
Maximum \| Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	4.75%
Maximum \| Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	3.90%
Maximum \| Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Stated interest rates	8.80%
Maximum \| FHLB advances
Debt Instrument [Line Items]
Stated interest rates	5.36%
Maximum \| Other borrowings
Debt Instrument [Line Items]
Stated interest rates	13.38%

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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