Accounting Policies (Details) $ in Millions		12 Months Ended
	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($) office	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)		Jan. 01, 2018 USD ($)
Lease liabilities		$ 2,170
Right-of-use assets		2,000
Cumulative effect of ASU adoptions					$ 62	[1]	$ (16)	[2]
Charge off threshold - small business commercial loans		$ 1
Number of international offices | office		4
Total allowance		$ 3,060
Investment securities – held to maturity		17,661	$ 19,312
Held-to-maturity securities, fair value		18,044	19,019
Securities available for sale debt securities, amortized cost		67,790	63,514
Investment securities – available for sale		69,163	63,389
Other Comprehensive Income (Loss), before Tax		$ 1,966	$ (739)	$ 131
Minimum | Furniture and Equipment
Estimated useful life of property and equipment		1 year
Minimum | Software and Software Development Costs
Estimated useful life of property and equipment		1 year
Maximum | Furniture and Equipment
Estimated useful life of property and equipment		10 years
Maximum | Buildings
Estimated useful life of property and equipment		40 years
Maximum | Leasehold Improvements
Estimated useful life of property and equipment		15 years
Maximum | Software and Software Development Costs
Estimated useful life of property and equipment		10 years
Forecast
Total allowance	$ 3,721
Accounting Standards Update 2016-02
Lease liabilities					2,100
Right-of-use assets					2,000
Accounting Standards Update 2016-13 | Forecast
Total allowance	3,700
Accounting Standards Update 2019-04 | Forecast
Investment securities – held to maturity	(16,200)
Held-to-maturity securities, fair value	(16,500)
Securities available for sale debt securities, amortized cost	16,200
Investment securities – available for sale	16,500
Other Comprehensive Income (Loss), before Tax	$ 306
Retained Earnings
Cumulative effect of ASU adoptions					62		$ (22)
Retained Earnings | Accounting Standards Update 2016-02
Cumulative effect of ASU adoptions					$ 83

[1] Represents the impact of the adoption of ASU 2016-02 related primarily to deferred gains on previous sale-leaseback transactions. See the Recently Adopted Accounting Standards portion of Note 1 Accounting Policies for additional detail.

[2] Represents the cumulative effect of adopting ASU 2014-09, ASU 2016-01, ASU 2017-12 and ASU 2018-02. See the Recently Adopted Accounting Standards portion of Note 1 Accounting Policies in our 2018 Form 10-K for additional detail on the adoption of these ASUs.