Regulatory Requirements - Narrative (Details)	9 Months Ended
	Sep. 30, 2019
Brokers and Dealers [Abstract]
Common Equity Tier 1 capital conservation buffer requirement (as a percent)	2.50%
Common Equity Tier 1 G-SIB capital surcharge requirement (as a percent)	3.00%
Common Equity Tier 1 CCyB requirement (as a percent)	2.50%
Proportion of phased-in Common Equity Tier 1 capital requirements (as a percent)	75.00%