Credit Quality and the Allowance for Loan and Lease Losses - Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment (Details) - USD ($) $ in Millions		Jun. 30, 2020		Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019		Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated		$ 308				$ 170
Collectively evaluated		2,388				911
Unallocated						121
Total ALLL		2,696	[1]	$ 2,348	$ 33	1,202	[1]	$ 1,115	$ 1,115	$ 1,103
Individually evaluated		2,042				1,529
Collectively evaluated		112,264				107,295
Purchased credit deteriorated		562				551
Total portfolio loans and leases		114,868				109,375
Leveraged leases		382				429
Loans	[1],[2]	115,053				109,558
Residential mortgage loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Residential mortgage loans		185				183
Leveraged Leases
Financing Receivable, Allowance for Credit Loss [Line Items]
Total ALLL		3				1
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated		167				82
Collectively evaluated		1,335				628
Unallocated						0
Total ALLL		1,502		1,313		710		651	654	645
Individually evaluated		939				413
Collectively evaluated		74,082				69,047
Purchased credit deteriorated		413				498
Total portfolio loans and leases		75,434				69,958
Loans		75,434				69,958
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated		91				55
Collectively evaluated		236				18
Unallocated						0
Total ALLL		327		260		73		76	79	81
Individually evaluated		809				814
Collectively evaluated		15,336				15,690
Purchased credit deteriorated		127				37
Total portfolio loans and leases		16,272				16,541
Residential mortgage loans		185				183
Residential Mortgage | Residential mortgage loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans		16,272
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated		50				33
Collectively evaluated		817				265
Unallocated						0
Total ALLL		867		775		298		276	270	267
Individually evaluated		294				302
Collectively evaluated		22,846				22,558
Purchased credit deteriorated		22				16
Total portfolio loans and leases		23,162				22,876
Loans		39,619				39,600
Consumer | Residential mortgage loans | GNMA loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans		82
Unallocated
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated						0
Collectively evaluated						0
Unallocated						121
Total ALLL		$ 0		$ 0		121		$ 112	$ 112	$ 110
Individually evaluated						0
Collectively evaluated						0
Purchased credit deteriorated						0
Total portfolio loans and leases						$ 0

[1] Includes $66 and $74 of other short-term investments, $1,032 and $1,354 of portfolio loans and leases, $(14) and $(7) of ALLL, $7 and $8 of other assets, $2 and $2 of other liabilities, and $933 and $1,253 of long-term debt from consolidated VIEs that are included in their respective captions above at June 30, 2020 and December 31, 2019, respectively. For further information refer to Note 13.

[2] Includes $185 and $183 of residential mortgage loans measured at fair value at June 30, 2020 and December 31, 2019, respectively.