Deposits with Clearing Organizations, Brokers and Banks	12 Months Ended
	Dec. 31, 2019
Deposits with Clearing Organizations, Brokers and Banks [Abstract]
Deposits with Clearing Organizations, Brokers and Banks	Deposits with Clearing Organizations, Brokers and BanksUnder the terms of agreements between the Company and some of its clearing organizations, brokers and banks, balances owed are collateralized by certain of the Company's cash and securities balances. As of December 31, 2019 and 2018, the Company had a total of $91.8 million and $89.4 million, respectively, in deposit accounts with clearing organizations, brokers and banks that could be used as collateral to offset losses incurred by the clearing organizations, brokers and banks, on behalf of the Company's activities, if such losses were to occur.