Securities Owned	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Securities Owned	Securities OwnedSecurities owned primarily consist of unencumbered U.S. Treasury bills held for liquidity purposes. Total securities owned were $40.8 million and $58.6 million as of December 31, 2021 and 2020, respectively. For additional information, see Note 13—“Fair Value of Financial Assets and Liabilities.”