Strategic Initiatives - Branch Closings (Details) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($) branch	Dec. 31, 2019 branch	Jun. 30, 2020 USD ($)
Restructuring Cost and Reserve [Line Items]
Number of branches closing | branch		60	20
Allocated restructuring costs from HTSU	$ 32			$ 42
Occupancy Expense, Net [Member]
Restructuring Cost and Reserve [Line Items]
Lease impairment charges	(6)	$ 52
Fixed asset impairment charges		$ 16
2-year Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Trading losses associated with exit of certain derivative contracts	$ 10