Goodwill and Other Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in the carrying amount of goodwill
Goodwill, Impairment Loss	$ 1,600	$ 1,614	$ 0	$ 0
Goodwill		1,764	3,301
Goodwill, Acquired During Period		77
Goodwill, Gross		3,378
Goodwill, Impaired, Accumulated Impairment Loss		1,614
Global Corporate & Investment Banking U.S. [Member]
Changes in the carrying amount of goodwill
Goodwill	$ 667
Operating segments | Global Corporate & Investment Banking U.S. [Member]
Changes in the carrying amount of goodwill
Goodwill, Impairment Loss		191
Goodwill		667	840
Goodwill, Acquired During Period		18
Goodwill, Gross		858
Goodwill, Impaired, Accumulated Impairment Loss		191
Operating segments | Regional Bank
Changes in the carrying amount of goodwill
Goodwill, Impairment Loss		1,423
Goodwill		770	2,134
Goodwill, Acquired During Period		59
Goodwill, Gross		2,193
Goodwill, Impaired, Accumulated Impairment Loss		1,423
Operating segments | Transaction Banking
Changes in the carrying amount of goodwill
Goodwill, Impairment Loss		0
Goodwill		251	251
Goodwill, Acquired During Period		0
Goodwill, Gross		251
Goodwill, Impaired, Accumulated Impairment Loss		0
Other (1)
Changes in the carrying amount of goodwill
Goodwill, Impairment Loss		0
Goodwill		76	$ 76
Goodwill, Acquired During Period		0
Goodwill, Gross		76
Goodwill, Impaired, Accumulated Impairment Loss		$ 0