Deposits and Borrowings - Long-Term Debt (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Time Deposits, at or Above FDIC Insurance Limit	$ 1,300	$ 894
Long-term Debt and Capital Lease Obligations	59,705	59,468
Debt and Capital Lease Obligations	$ 60,281	60,460
Securitized debt obligations
Debt Instrument [Line Items]
Weighted average interest rate	1.89%
Long-term debt	$ 20,010	18,826
Total senior and subordinated notes
Debt Instrument [Line Items]
Long-term debt	$ 30,755	23,431
Senior notes \| Total unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	2.66%
Long-term debt	$ 26,222	18,899
Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	2.72%
Long-term debt	$ 22,776	17,546
Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	2.27%
Long-term debt	$ 3,446	1,353
Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Weighted average interest rate	4.09%
Long-term debt	$ 4,533	4,532
FHLB advances
Debt Instrument [Line Items]
Weighted average interest rate	1.45%
Long-term debt	$ 8,609	17,179
Capital Lease Obligation and GPMH
Debt Instrument [Line Items]
Weighted average interest rate	7.40%
Long-term debt	$ 331	32
FHLB Advance Capital Lease Obligation and GPMH
Debt Instrument [Line Items]
Long-term debt	$ 8,940	$ 17,211
Minimum [Member] \| Securitized debt obligations
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.33%
Minimum [Member] \| Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.50%
Minimum [Member] \| Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.83%
Minimum [Member] \| Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.38%
Minimum [Member] \| FHLB advances
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.38%
Minimum [Member] \| Capital Lease Obligation and GPMH
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.00%
Maximum [Member] \| Securitized debt obligations
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.75%
Maximum [Member] \| Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.75%
Maximum [Member] \| Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.75%
Maximum [Member] \| Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.80%
Maximum [Member] \| FHLB advances
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.36%
Maximum [Member] \| Capital Lease Obligation and GPMH
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	16.75%

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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