Loans - Delinquency Ratio for Consumer Loan (Detail) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		$ 72,468	$ 68,553
Residential Mortgage Loan Delinquency Carried At Lower Of Amortized Cost Or Fair Value Less Cost To Sell		243	256
Consumer Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		2,389
2019		2,902
2018		1,723
2017		1,974
2016		2,292
Prior		8,034
Revolving Loans		1,241
Total loans		20,555	20,342
Mortgage Loans in Process of Foreclosure, Amount		122	142
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		2,304
2019		2,790
2018		1,679
2017		1,933
2016		2,239
Prior		7,336
Revolving Loans		0
Total loans		18,281	17,801
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		27
2019		54
2018		43
2017		39
2016		50
Prior		579
Revolving Loans		0
Total loans		792	853
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		0
2019		0
2018		0
2017		0
2016		0
Prior		0
Revolving Loans		1,175
Total loans		1,175	1,405
Consumer Loans [Member] | Other consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		58
2019		58
2018		1
2017		2
2016		3
Prior		119
Revolving Loans		66
Total loans	[1]	307	283
Consumer Loans [Member] | Contractual Delinquency, 60 Days or More Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		24
2019		6
2018		11
2017		28
2016		17
Prior		359
Revolving Loans		41
Total loans		486	416
Consumer Loans [Member] | Contractual Delinquency, 60 Days or More Past Due [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		23
2019		5
2018		11
2017		28
2016		17
Prior		329
Revolving Loans		0
Total loans		413	350
Consumer Loans [Member] | Contractual Delinquency, 60 Days or More Past Due [Member] | Home Equity Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		0
2019		0
2018		0
2017		0
2016		0
Prior		27
Revolving Loans		0
Total loans		27	25
Consumer Loans [Member] | Contractual Delinquency, 60 Days or More Past Due [Member] | Credit Cards [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020
2019
2018
2017
2016
Prior
Revolving Loans		38
Total loans		38	34
Consumer Loans [Member] | Contractual Delinquency, 60 Days or More Past Due [Member] | Other consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020		1
2019		1
2018		0
2017		0
2016		0
Prior		3
Revolving Loans		3
Total loans		$ 8	$ 7

[1] Includes certain student loans that we have elected to designate under the fair value option and are therefore carried at fair value, which totaled $35 million at June 30, 2020. See Note 10, "Fair Value Option," for further details.