Benefit Plans - Summary of the Component of Net Periodic Benefit Cost (Inactive Plan) - (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Heritage BBT
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost		$ 226	$ 201	$ 192
Estimated return on plan assets		460	448	372
Net periodic benefit cost		91	72	95
Net actuarial loss (gain)		62	289	137
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Reclassification Adjustment, before Tax		(48)	208	92
Total net periodic pension costs (income) recognized in total comprehensive income, pre-tax		$ 43	$ 280	$ 187
Discount rate		4.43%	3.79%	4.43%
Expected long-term rate of return on plan assets		7.00%	7.00%	7.00%
SunTrust Banks Inc.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	$ 7
Estimated return on plan assets	(21)
Net periodic benefit cost	(14)
Net actuarial loss (gain)	(28)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Reclassification Adjustment, before Tax	(28)
Total net periodic pension costs (income) recognized in total comprehensive income, pre-tax	$ (42)
Discount rate	3.22%
Expected long-term rate of return on plan assets	6.90%