Federal Funds Sold and Securities Financing Activities Securities Sold Under Agreements to Repurchase (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	$ 1,814	$ 1,774
US Treasury Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	122	204
US Government Agencies Debt Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	32	122
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	1,046	916
Commercial Paper [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	108	78
Corporate Debt Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	506	454
Maturity Overnight [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	1,389	1,484
Maturity Overnight [Member] | US Treasury Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	122	197
Maturity Overnight [Member] | US Government Agencies Debt Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	23	112
Maturity Overnight [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	898	881
Maturity Overnight [Member] | Commercial Paper [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	108	78
Maturity Overnight [Member] | Corporate Debt Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	238	216
Maturity up to 30 days [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	425	210
Maturity up to 30 days [Member] | US Treasury Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	0	7
Maturity up to 30 days [Member] | US Government Agencies Debt Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	9	10
Maturity up to 30 days [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	148	35
Maturity up to 30 days [Member] | Commercial Paper [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	0	0
Maturity up to 30 days [Member] | Corporate Debt Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase	$ 268	158
Maturity 30 to 90 Days [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase		80
Maturity 30 to 90 Days [Member] | US Treasury Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase		0
Maturity 30 to 90 Days [Member] | US Government Agencies Debt Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase		0
Maturity 30 to 90 Days [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase		0
Maturity 30 to 90 Days [Member] | Commercial Paper [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase		0
Maturity 30 to 90 Days [Member] | Corporate Debt Securities [Member]
securities sold under agreement to repurchase maturity [Line Items]
Securities Sold under Agreements to Repurchase		$ 80