Benefit Plans - Schedule of Fair Value of Pension Plan Assets by Three Level Fair Value Hierarchy (Details) - Heritage BBT - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7,884	$ 5,669
Cash and cash-equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	196	21
U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,489	2,323
International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,094	797
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,105	2,528
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,239	1,397
Level 1 | Cash and cash-equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	196	21
Level 1 | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,782	1,204
Level 1 | International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	250	161
Level 1 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	11
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,645	4,272
Level 2 | Cash and cash-equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,707	1,119
Level 2 | International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	844	636
Level 2 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 3,094	$ 2,517
Minimum | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	30.00%
Minimum | International equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	11.00%
Minimum | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	35.00%
Maximum | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	50.00%
Maximum | International equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	18.00%
Maximum | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	53.00%