Benefit Plans - Changes in Fair Value of Plan Assets (Inactive Plans) - (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 06, 2019	Dec. 31, 2017
Heritage BBT
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7,884	$ 7,884	$ 5,669
Heritage BBT | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8,244	8,244	5,968		$ 6,309
Actual return on plan assets		1,525	(397)
Employer contributions		876	169
Defined Benefit Plan, Plan Assets, Benefits Paid		125	113
Funded status, end of year	2,215	2,215	1,271
Heritage BBT | Nonqualified Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0	0		$ 0
Actual return on plan assets		0	0
Employer contributions		13	13
Defined Benefit Plan, Plan Assets, Benefits Paid		13	13
Funded status, end of year	(484)	(484)	$ (386)
SunTrust Banks Inc.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,128	4,128
SunTrust Banks Inc. | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,155	4,155		$ 3,303
Actual return on plan assets	42
Employer contributions	820
Defined Benefit Plan, Plan Assets, Benefits Paid	10
Funded status, end of year	1,365	1,365
SunTrust Banks Inc. | Nonqualified Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0		$ 0
Actual return on plan assets	0
Employer contributions	0
Defined Benefit Plan, Plan Assets, Benefits Paid	0
Funded status, end of year	$ (73)	$ (73)