Derivative and Hedging Activities - Schedule of Cumulative Basis Adjustment for Fair Value Hedges (Details) - Loans and Leases - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of the Hedged Assets	$ 50	$ 73
Fair Value Hedging
Derivative [Line Items]
Carrying Amount of the Hedged Assets	2,050	2,073
Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of the Hedged Assets	$ 50	$ 73