Regulatory Authorities - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
EGL [Member]
Regulatory Authorities [Line Items]
Alternative Net Capital Requirement	$ 250,000
Net Capital	74,009,000	$ 74,080,000
Alternative excess net capital	73,759,000	73,830,000
International Strategy & Investment Group LLC [Member]
Regulatory Authorities [Line Items]
Alternative Net Capital Requirement	250,000
Net Capital	23,977,000	7,548,000
Alternative excess net capital	23,727,000	$ 7,298,000
Evercore Trust Company [Member]
Regulatory Authorities [Line Items]
Tier One Capital	5,000,000
Minimum liquid assets, amount	$ 3,500,000
Coverage of operating expenses (in days)	90 days
Collateral held in a segregated account at a third-party depository institution	$ 10,000,000