Cash and Securities Segregated Under Federal Regulations and Other Requirements	12 Months Ended
Dec. 31, 2021
Brokers and Dealers [Abstract]
Cash and Securities Segregated Under Federal Regulations and Other Requirements	Cash and Securities Segregated Under Federal Regulations and Other RequirementsAs of December 31, 2021 and 2020, $1.5 billion and $1.8 billion, respectively, of U.S. Treasury Bills were segregated in a special reserve bank custody account for the exclusive benefit of our brokerage customers under Rule 15c3-3 of the Exchange Act.

The entire disclosure for assets that are restricted in their use, generally by contractual agreements or regulatory requirements. This would include, but not limited to, a description of the restricted assets and the terms of the restriction.

No definition available.

Name:	us-gaap_RestrictedAssetsDisclosureTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration