Certain Transfers of Financial Assets and Variable Interest Entities - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Loans and Leases Receivable, Net Amount		$ 153,590		$ 150,224
Total liabilities		195,602		191,263
Long-term Debt	[1]	17,395		15,072
Debt Securities, Trading, and Equity Securities, FV-NI	[2]	6,259		5,506
Amortization of Intangible Assets	[3]	3	$ 5
Variable Interest Entity, Not Primary Beneficiary [Member]
Investment Tax Credit		18	18
Amortization of Intangible Assets		15	14
Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt		156		161
Residential Mortgage [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Loans and Leases Receivable, Gain (Loss) on Sales, Net		49	13
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Loans and Leases Receivable, Gain (Loss) on Sales, Net		7	$ 9
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Loans and Leases Receivable, Net Amount		159		165
Long-term Debt		$ 156		$ 161
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Government Guarantee Percent		98.00%		98.00%
Total Return Swap [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Derivative Asset, Notional Amount		$ 2,200		$ 2,000
Debt Securities, Trading, and Equity Securities, FV-NI		$ 2,200		$ 2,000
Death, Disability, Bankruptcy [Member] | Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Government Guarantee Percent		100.00%

[1] Includes debt of consolidated VIEs of $156 million and $161 million at March 31, 2019 and December 31, 2018, respectively.

[2] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,382 million and $1,442 million at March 31, 2019 and December 31, 2018, respectively.

[3] Does not include expense associated with community development investments. See Note 11, “Certain Transfers of Financial Assets and Variable Interest Entities,” for additional information.