Benefit Plans - Schedule of Fair Value of Pension Plan Assets by Three Level Fair Value Hierarchy (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 13,859	$ 12,012
Cash and cash-equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		290	295
U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	6,587	5,336
International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,614	1,752
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		5,368	4,629
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		4,192	4,263
Level 1 | Cash and cash-equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		290	295
Level 1 | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	3,531	3,629
Level 1 | International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		360	328
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		9,667	7,749
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]	3,056	1,707
Level 2 | International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,254	1,424
Level 2 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 5,357	$ 4,618
Minimum | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	[1]	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	[1]	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%

[1] The plan may hold up to 10% of its assets in Truist common stock.