Regulatory Authorities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
LFNY [Member]
Regulatory Requirements [Line Items]
Specified fixed percentage, minimum required capital	6.67%
Minimum net capital requirement as defined under securities exchange act	$ 100
Regulatory capital	180,909
Regulatory capital in excess of minimum requirement	178,043
U.K. Subsidiaries [Member]
Regulatory Requirements [Line Items]
Regulatory capital	91,003
Regulatory capital in excess of minimum requirement	72,842
CFLF [Member]
Regulatory Requirements [Line Items]
Regulatory capital	139,613
Regulatory capital in excess of minimum requirement	102,948
Other U.S. and Non-U.S. Subsidiaries [Member]
Regulatory Requirements [Line Items]
Regulatory capital	100,054
Regulatory capital in excess of minimum requirement	$ 72,757