Capital Requirements (Details) - USD ($)	Jan. 02, 2021	Dec. 31, 2020	Jan. 02, 2020	Dec. 31, 2019
MSCO [Member]
Net capital		$ 27,500,000		$ 4,400,000
Minimum net capital required		2,300,000		250,000
Net capital in excess of minimum requirement		$ 25,200,000		4,200,000
Percentage of aggregate debit balance to net capital		24.00%
Cash deposits		$ 324,900,000
Minimum cash deposits required		319,900,000
Cash deposits in excess of minimum requirement		5,000,000
MSCO [Member] | Subsequent Event [Member]
Cash deposits in excess of minimum requirement	$ 1,000,000
StockCross [Member]
Net capital				18,800,000
Minimum net capital required				2,100,000
Net capital in excess of minimum requirement				$ 16,700,000
Percentage of aggregate debit balance to net capital				18.00%
Cash deposits				$ 222,100,000
Minimum cash deposits required				219,400,000
Cash deposits in excess of minimum requirement			$ 1,000,000	4,000,000
Fair value of Securities on Deposit				1,300,000
Segregated cash				1,400,000
StockCross [Member] | Special Reserve Account [Member]
Deposits				223,400,000
Cash deposits in excess of minimum requirement			$ 218,000
Segregated cash				1,400,000
Minimum cash deposit requirement				1,700,000
Cash deposits in deficit of minimum requirement				282,000
Weeden Prime Services LLC [Member]
Net capital		3,900,000		3,700,000
Minimum net capital required		$ 250,000		250,000
Special reserve bank account				$ 110,000