Subsequent Events - Narrative (Details) - USD ($) $ / shares in Units, $ in Billions	Feb. 07, 2019	Dec. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Par value, per share		$ 5	$ 5
Subsequent Event
Subsequent Event [Line Items]
mutual break-up fee	$ 1.1
BB&T Corporation | Subsequent Event
Subsequent Event [Line Items]
Par value, per share	$ 5
Business Combination Equity Interests Received Per Share | BB&T Corporation | Subsequent Event
Subsequent Event [Line Items]
Business Combination Equity Interests Received Per Share	1.295
SunTrust | Subsequent Event
Subsequent Event [Line Items]
Par value, per share	$ 1