Regulatory Authorities - Additional Information (Detail)	Dec. 31, 2021 USD ($)
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	195,103,000
Regulatory capital in excess of minimum requirement	$ 188,205,000
Aggregate indebtedness to net capital ratio	0.53
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	$ 173,961,000
Regulatory capital in excess of minimum requirement	151,120,000
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	225,278,000
Regulatory capital in excess of minimum requirement	$ 195,849,000