Fair Values - Gains (Losses) on Borrowings under the Fair Value Option (Details) - Borrowings - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value Option Quantitative Disclosures
Earnings impact	$ (2,284)	$ 786	$ (5,280)	$ 710
Trading revenues
Fair Value Option Quantitative Disclosures
Earnings impact	(2,190)	859	(5,093)	885
Interest expense
Fair Value Option Quantitative Disclosures
Earnings impact	$ (94)	$ (73)	$ (187)	$ (175)