Fair Value (Schedule of Carrying Values and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
HTM investment securities	$ 461	$ 640
Time deposits	1,688	2,588
Long-term debt	1,020	1,336
Level 2 | Carrying value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
HTM investment securities	459	636
Time deposits	1,688	2,588
Long-term debt	1,020	1,336
Level 2 | Estimated fair value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
HTM investment securities	461	640
Time deposits	1,695	2,603
Long-term debt	1,056	1,346
Level 3 | Carrying value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans and leases (including loans held for sale), net of allowance	50,254	52,780
Level 3 | Estimated fair value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans and leases (including loans held for sale), net of allowance	$ 50,648	$ 53,221