Commitments, Pledged Assets and Collateral - Pledged Assets and Collateral (Details) - USD ($) $ in Billions	Dec. 31, 2018	Dec. 31, 2017
Significant components of assets pledged
Assets that may be sold or repledged or otherwise used by secured parties	$ 104.0	$ 135.8
Assets that may not be sold or repledged or otherwise used by secured parties	83.7	68.1
Total assets pledged	663.0	697.6
Collateral Received that Can be Resold or Repledged
Collateral permitted to be sold or repledged, delivered, or otherwise used	1,245.3	968.8
Collateral sold, repledged, delivered or otherwise used	998.3	771.0
Investment securities
Significant components of assets pledged
Total assets pledged	59.5	86.2
Loans
Significant components of assets pledged
Total assets pledged	440.1	437.7
Trading assets and other
Significant components of assets pledged
Total assets pledged	163.4	173.7
Assets pledged at Federal Reserve banks and FHLBs
Significant components of assets pledged
Total assets pledged	$ 475.3	$ 493.7