Activity in the Allowance for Credit Losses (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components:
Allowance for credit losses		$ 1,814		$ 1,776	$ 1,815	$ 1,991
Provision for loan losses		397		440	156
Provision for Other Credit Losses		12		4	9
Allowance for Loan and Lease Losses, Write-offs		(491)		(591)	(470)
Loan recoveries		124		108	129
Allowance for Loan and Lease Losses, Period Increase (Decrease)		(4)	[1]	0	0
Loans and Leases Receivable, Allowance		1,735		1,709	1,752
Unfunded commitments reserve	[2]	$ 79		$ 67	$ 63

[1] Related to loans disposed in connection with the sale of PAC. For additional information regarding the sale of PAC, see Note 2, "Acquisitions/Dispositions."

[2] The unfunded commitments reserve is recorded in Other liabilities in the Consolidated Balance Sheets.