Regulatory Requirements (Narrative) (Details)	3 Months Ended
	Mar. 31, 2018
Regulatory Requirements
Description of regulatory requirements on capital adequacy	In addition to the minimum risk-based capital ratio requirements, by 2019 the Firm will be subject to the following buffers: A greater than 2.5% Common Equity Tier 1 capital conservation buffer; The Common Equity Tier 1 G-SIB capital surcharge, currently at 3%; and Up to a 2.5% Common Equity Tier 1 CCyB, currently set by U.S. banking agencies at zero.
Description of possible effects of noncompliance	In 2017 and 2018, each of the buffers is 50% and 75%, respectively, of the 2019 requirement noted above. Failure to maintain the buffers will result in restrictions on the Firm’s ability to make capital distributions, including the payment of dividends and the repurchase of stock, and to pay discretionary bonuses to executive officers.