Benefit Plans - Schedule of Fair Value of Pension Plan Assets by Three Level Fair Value Hierarchy (Inactive Plans) - (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Heritage BBT
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7,884	$ 5,669
Heritage BBT | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,239	1,397
Heritage BBT | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,645	4,272
Heritage BBT | Cash and cash-equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	196	21
Heritage BBT | Cash and cash-equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	196	21
Heritage BBT | Cash and cash-equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Heritage BBT | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 3,489	2,323
Heritage BBT | U.S. equity securities | Min
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	30.00%
Heritage BBT | U.S. equity securities | Max
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	50.00%
Heritage BBT | U.S. equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,782	1,204
Heritage BBT | U.S. equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,707	1,119
Heritage BBT | International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,094	797
Heritage BBT | International equity securities | Min
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	11.00%
Heritage BBT | International equity securities | Max
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	18.00%
Heritage BBT | International equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 250	161
Heritage BBT | International equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	844	636
Heritage BBT | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 3,105	2,528
Heritage BBT | Fixed income securities | Min
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	35.00%
Heritage BBT | Fixed income securities | Max
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	53.00%
Heritage BBT | Fixed income securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 11	11
Heritage BBT | Fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,094	2,517
SunTrust Banks Inc.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,128
SunTrust Banks Inc. | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 2,024
SunTrust Banks Inc. | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			$ 2,104
SunTrust Banks Inc. | Cash and cash-equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 99
SunTrust Banks Inc. | Cash and cash-equivalents | Min
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%
SunTrust Banks Inc. | Cash and cash-equivalents | Max
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%
SunTrust Banks Inc. | Cash and cash-equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 99
SunTrust Banks Inc. | Cash and cash-equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
SunTrust Banks Inc. | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,847
SunTrust Banks Inc. | U.S. equity securities | Min
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	30.00%
SunTrust Banks Inc. | U.S. equity securities | Max
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	60.00%
SunTrust Banks Inc. | U.S. equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,847
SunTrust Banks Inc. | U.S. equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
SunTrust Banks Inc. | International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 658
SunTrust Banks Inc. | International equity securities | Min
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%
SunTrust Banks Inc. | International equity securities | Max
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15.00%
SunTrust Banks Inc. | International equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 78
SunTrust Banks Inc. | International equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	580
SunTrust Banks Inc. | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,524
SunTrust Banks Inc. | Fixed income securities | Min
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	20.00%
SunTrust Banks Inc. | Fixed income securities | Max
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	60.00%
SunTrust Banks Inc. | Fixed income securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0
SunTrust Banks Inc. | Fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,524