Credit Quality (Recorded Investment in Portfolio Loans and Leases by Age and Class) (Detail) - USD ($) $ in Millions	Mar. 31, 2019		Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	$ 108,999	[1],[2]	$ 94,487	[3],[4]
Total Past Due	653	[2]	599	[4]
Total portfolio loans and leases	109,652		95,086
90-Days past Due and Still Accruing	132	[2]	93	[4]
30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	364		326
90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	289		273
Commercial and Industrial Loans
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	51,737		44,213
Total Past Due	125		127
Total portfolio loans and leases	51,862		44,340
90-Days past Due and Still Accruing	15		4
Commercial and Industrial Loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	53		32
Commercial and Industrial Loans | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	72		95
Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	4,384		3,277
Total Past Due	28		7
Total portfolio loans and leases	4,412		3,284
90-Days past Due and Still Accruing	8		2
Commercial Mortgage Loans, Owner-occupied | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	16		1
Commercial Mortgage Loans, Owner-occupied | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	12		6
Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	6,256		3,688
Total Past Due	18		2
Total portfolio loans and leases	6,274		3,690
90-Days past Due and Still Accruing	12		0
Commercial Mortgage Loans, Nonowner-Occupied | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3		1
Commercial Mortgage Loans, Nonowner-Occupied | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	15		1
Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	5,230		4,657
Total Past Due	1		0
Total portfolio loans and leases	5,231		4,657
90-Days past Due and Still Accruing	0		0
Commercial construction loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1		0
Commercial construction loans | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	0		0
Commercial Leases
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	3,904		3,597
Total Past Due	5		3
Total portfolio loans and leases	3,909		3,600
90-Days past Due and Still Accruing	0		0
Commercial Leases | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	5		1
Commercial Leases | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	0		2
Residential Mortgage
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	16,512		15,227
Total Past Due	109		98
Total portfolio loans and leases	16,621		15,325
90-Days past Due and Still Accruing	48		38
Residential Mortgage | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	36		37
Residential Mortgage | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	73		61
Home Equity
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	6,300		6,280
Total Past Due	135		122
Total portfolio loans and leases	6,435		6,402
90-Days past Due and Still Accruing	1		0
Home Equity | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	78		71
Home Equity | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	57		51
Indirect secured consumer loans
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	9,907		8,844
Total Past Due	124		132
Total portfolio loans and leases	10,031		8,976
90-Days past Due and Still Accruing	9		12
Indirect secured consumer loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	110		119
Indirect secured consumer loans | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	14		13
Credit Card
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	2,301		2,381
Total Past Due	87		89
Total portfolio loans and leases	2,388		2,470
90-Days past Due and Still Accruing	38		37
Credit Card | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	44		47
Credit Card | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	43		42
Other consumer loans
Financing Receivable, Recorded Investment, Past Due
Current Loans and Leases	2,468		2,323
Total Past Due	21		19
Total portfolio loans and leases	2,489		2,342
90-Days past Due and Still Accruing	1		0
Other consumer loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	18		17
Other consumer loans | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 3		$ 2

[1] Includes accrual and nonaccrual loans and leases.

[2] Excludes $ 190 of residential mortgage loans measured at fair value at March 31, 2019 .

[3] Includes accrual and nonaccrual loans and leases.

[4] Excludes $ 179 of residential mortgage loans measured at fair value at December 31, 2018 .