Capital Requirements (Details) - USD ($)	Jul. 02, 2020	Jun. 30, 2020	Jan. 02, 2020	Dec. 31, 2019
MSCO [Member]
Net capital		$ 24,800,000		$ 4,400,000
Minimum net capital required		1,900,000		250,000
Net capital in excess of minimum requirement		$ 22,900,000		4,200,000
Percentage of aggregate debit balance to net capital		25.70%
Cash deposits		$ 255,600,000
Minimum cash deposits required		242,200,000
Cash deposits in excess of minimum requirement		13,400,000
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				17.60%
Cash deposits				$ 222,100,000
Minimum cash deposits required				4,000,000
Cash deposits in excess of minimum requirement			$ 1,000,000	219,400,000
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				1,400,000
Deposit in deficit of minimum requirement				282,000
Cash deposits in excess of minimum requirement			$ 218,000	1,700,000
Weeden Prime Services LLC [Member]
Net capital		4,000,000		3,900,000
Minimum net capital required		250,000		250,000
Net capital in excess of minimum requirement		$ 3,700,000		$ 3,700,000