Clearing Operations (Investment Policy) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Clearing Operations [Line Items]
Cash contributions	$ 13,902
Default funds and margin deposits assets	6,570	$ 5,911
Restricted cash and equivalents
Clearing Operations [Line Items]
Default funds and margin deposits assets	5,398	5,074
Demand deposits
Clearing Operations [Line Items]
Default funds and margin deposits assets	4,270	3,061
Central bank certificates
Clearing Operations [Line Items]
Default funds and margin deposits assets	1,128	2,013
Investments
Clearing Operations [Line Items]
Default funds and margin deposits assets	1,172	837
European government debt securities
Clearing Operations [Line Items]
Default funds and margin deposits assets	443	414
Reverse repurchase agreements
Clearing Operations [Line Items]
Default funds and margin deposits assets	457	152
Multilateral development bank debt securities
Clearing Operations [Line Items]
Default funds and margin deposits assets	272	271
Nasdaq clearing members cash contributions
Clearing Operations [Line Items]
Cash contributions	$ 6,570	$ 5,911