Fair Value Disclosures - Financial Assets and Liabilities Not Recorded at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financial assets:
Loans and leases HFI, net of ALLL	$ 300,764	$ 298,293
Financial liabilities:
Long-term debt	41,008	41,339
Carrying Amount
Financial assets:
Loans and leases HFI, net of ALLL	300,764	298,293
Financial liabilities:
Time deposits	25,900	35,896
Long-term debt	41,008	41,339
Fair Value | Level 2
Financial liabilities:
Time deposits	26,085	35,885
Long-term debt	42,186	42,051
Fair Value | Level 3
Financial assets:
Loans and leases HFI, net of ALLL	$ 303,210	$ 298,586