Activity in the Allowance for Credit Losses (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Components:
Allowance for credit losses		$ 1,684		$ 1,814		$ 1,776
Provision for loan losses		218		397		440
Provision for Other Credit Losses		(10)	[1]	12	[2]	4	[3]
Allowance for Loan and Lease Losses, Write-offs		(453)		(491)		(591)
Loan recoveries		115		124		108
Allowance for Loan and Lease Losses, Adjustments, Other	[4]			(4)
Loans and Leases Receivable, Allowance		1,615		1,735		1,709		$ 1,752
Unfunded commitments reserve		69	[1]	79	[1],[2]	67	[2],[3]	63	[3]
Commercial Portfolio Segment [Member]
Components:
Allowance for credit losses		1,149		1,180		1,191
Provision for loan losses		86		108		329
Provision for Other Credit Losses		(10)	[1]	12	[2]	4	[3]
Allowance for Loan and Lease Losses, Write-offs		(131)		(167)		(287)
Loan recoveries		24		40		35
Allowance for Loan and Lease Losses, Adjustments, Other	[4]			(4)
Loans and Leases Receivable, Allowance		1,080		1,101		1,124		1,047
Unfunded commitments reserve		69	[1]	79	[1],[2]	67	[2],[3]	63	[3]
Consumer Portfolio Segment [Member]
Components:
Allowance for credit losses		535		634		585
Provision for loan losses		132		289		111
Allowance for Loan and Lease Losses, Write-offs		(322)		(324)		(304)
Loan recoveries		91		84		73
Loans and Leases Receivable, Allowance		$ 535		$ 634		$ 585		$ 705

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

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

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

[4] Related to loans disposed in connection with the sale of PAC. For additional information regarding the sale of PAC, see Note 3, "Acquisitions/Dispositions."