Fair Value Disclosures - Financial Assets and Liabilities Not Recorded at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Financial assets:
Loans and leases HFI, net of ALLL	$ 314,018	$ 298,293
Financial liabilities:
Long-term debt	65,662	41,339
Carrying Amount
Financial assets:
Loans and leases HFI, net of ALLL	314,018	298,293
Financial liabilities:
Time deposits	35,539	35,896
Long-term debt	65,662	41,339
Fair Value | Level 2
Financial liabilities:
Time deposits	35,821	35,885
Long-term debt	64,998	42,051
Fair Value | Level 3
Financial assets:
Loans and leases HFI, net of ALLL	$ 314,838	$ 298,586