Pledged Assets and Collateral - Schedule of Pledged Assets (Details) - USD ($) $ in Billions	Sep. 30, 2021	Dec. 31, 2020
Pledged assets and Collateral
Assets that may be sold or repledged or otherwise used by secured parties	$ 122.4	$ 166.6
Assets that may not be sold or repledged or otherwise used by secured parties	115.3	113.9
Total pledged assets	700.6	735.8
Assets pledged at Federal Reserve banks and FHLBs
Pledged assets and Collateral
Total pledged assets	$ 462.9	$ 455.3