Capital Ratios (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Common Equity Tier One Capital	$ 17,141	$ 16,953
Common Equity Tier One Capital Ratio	9.74%	9.59%
Tier 1 capital	$ 19,622	$ 18,186
Total capital	$ 23,028	$ 21,685
Tier 1 capital	11.15%	10.28%
Total capital	13.09%	12.26%
Tier One Leverage Capital to Average Assets	9.80%	9.22%
Sun Trust Bank [Member]
Common Equity Tier One Capital	$ 19,474	$ 18,535
Common Equity Tier One Capital Ratio	11.29%	10.71%
Tier 1 capital	$ 19,496	$ 18,573
Total capital	$ 22,132	$ 21,276
Tier 1 capital	11.31%	10.73%
Total capital	12.83%	12.29%
Tier One Leverage Capital to Average Assets	9.97%	9.63%
Minimum [Member]
Common Equity Tier One Capital Ratio	4.50%
Tier 1 capital	6.00%
Total capital	8.00%
Tier One Leverage Capital to Average Assets	4.00%
Capital Required for Capital Adequacy to Risk Weighted Assets	2.50%