Commitments and Contingent Liabilities (Litigation Narrative) (Details) $ in Millions	1 Months Ended			3 Months Ended
	Dec. 31, 2017 defendant	Feb. 28, 2017 plaintiff	Jun. 30, 2014 case plaintiff	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Jan. 31, 2018 plaintiff	Feb. 28, 2015 plaintiff	Jul. 31, 2014 defendant	May 31, 2014 defendant
Loss Contingencies [Line Items]
Estimate of possible losses in excess of accruals (less than) for litigation and regulatory matters | $					$ 250.0
Residential mortgage-backed securities | Positive Outcome of Litigation
Loss Contingencies [Line Items]
Number of other institutions filing actions along with Company			9
Number of actions filed by the Company in New York state court | case			6
Number of Trusts represented in legal action filed by the Company (more than)			2,200
Number of defendants in legal action filed by the company | defendant								6
Residential mortgage-backed securities | PICA et al. v. Deutsche Bank, et al. | Positive Outcome of Litigation
Loss Contingencies [Line Items]
Loss Contingency, Claims Filed, Number		62
Loss Contingency, Pending Claims, Number		41
Loss Contingency, Claims Dismissed, Number		21
Residential mortgage-backed securities | PICA et al. v. U.S. Bank N.A. | Positive Outcome of Litigation
Loss Contingencies [Line Items]
Number of Trusts represented in legal action filed by the Company (more than)						77	770
London Interbank Offered Rate (LIBOR) | Positive Outcome of Litigation
Loss Contingencies [Line Items]
Number of defendants in legal action filed by the company | defendant									10
Pending Litigation | Total Asset Recovery Services, LLC v. MetLife, Inc., and Prudential
Loss Contingencies [Line Items]
Loss Contingency, Number of Defendants | defendant	19
Settled Litigation
Loss Contingencies [Line Items]
Litigation Settlement, Amount Awarded to Other Party | $				$ 5.0
Disgorgement Ruling
Loss Contingencies [Line Items]
Litigation Settlement, Amount Awarded to Other Party | $				$ 27.6