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

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

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