Regulatory Authorities - Additional Information (Detail) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
LFNY [Member]
Regulatory Requirements [Line Items]
Specified fixed percentage, minimum required capital	6.67%
Minimum net capital requirement as defined under exchange act	$ 5,000
Regulatory capital	46,066,000
Regulatory capital in excess of minimum requirement	$ 43,337,000
Aggregate indebtedness to net capital ratio	0.89
LFNY [Member] | Maximum [Member]
Regulatory Requirements [Line Items]
Aggregate indebtedness to net capital ratio	15
U.K. Subsidiaries [Member]
Regulatory Requirements [Line Items]
Regulatory capital	$ 169,363,000
Regulatory capital in excess of minimum requirement	107,228,000
CFLF [Member]
Regulatory Requirements [Line Items]
Regulatory capital		$ 143,046,000
Regulatory capital in excess of minimum requirement		72,846,000
Combined European Regulated Group [Member]
Regulatory Requirements [Line Items]
Regulatory capital		162,804,000
Regulatory capital in excess of minimum requirement		$ 80,912,000
Other U.S. and Non-U.S. Subsidiaries [Member]
Regulatory Requirements [Line Items]
Regulatory capital	186,506,000
Regulatory capital in excess of minimum requirement	$ 157,703,000