Derivative Financial Instruments - Cash Flow and Fair Value Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flow hedges
Derivative [Line Items]
Net unrecognized after-tax gain (loss) on active hedges recorded in AOCI	$ 0	$ (18)
Net unrecognized after-tax gain (loss) on terminated hedges recorded in AOCI (to be recognized in earnings through 2022)	(101)	(13)
Estimated portion of net after-tax gain (loss) on active and terminated hedges to be reclassified from AOCI into earnings during the next 12 months	(37)	$ 4
Maximum time period over which Truist is hedging a portion of the variability in future cash flows for forecasted transactions excluding those transactions relating to the payment of variable interest on existing instruments		4 years
Fair Value Hedges
Derivative [Line Items]
Unrecognized pre-tax net gain (loss) on terminated hedges (to be recognized as interest primarily through 2030)	(57)	$ (39)
Portion of pre-tax net gain (loss) on terminated hedges to be recognized as a change in interest during the next 12 months	$ (6)	$ 15