Share-Based and Other Deferred Compensation - Additional information (Detail) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense Related To Separation Benefits	$ 1,124,000	$ 186,000	$ 4,920,000	$ 4,775,000
Cash Payments Related To Separation Benefits	674,000	280,000	$ 2,205,000	3,281,000
Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long Term Incentive Plan Performance period (in years)			4 years
Long Term Incentive Plan Payment period (in years)			2 years
Deferred compensation arrangement compensation expense	1,547,000	1,043,000	$ 4,590,000	3,186,000
Employee Loans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation arrangement compensation expense	3,483,000	4,043,000	$ 12,434,000	9,693,000
Requisite service period (in years)			1 year
Maximum contractual term (in years)			5 years
Unamortized deferred compensation	24,119,000		$ 24,119,000
Equity Grants [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)			$ 48.41
Equity Grants [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)			$ 58.47
Equity Grants [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense related to Service-based Award	25,124,000	22,243,000	$ 80,083,000	69,334,000
Class H Interests [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class H Interests Performance Period (in years)			3 years
Class H Interests [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Management Basis EBIT Margin (as a percent)			7.00%
Management Basis EBIT			$ 8,000,000
Class H Interests [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Management Basis EBIT Margin (as a percent)			17.00%
Management Basis EBIT			$ 48,000,000
Class G Interests [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Management Basis EBIT Margin (as a percent)			12.00%
Class G Interests [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Management Basis EBIT Margin (as a percent)			16.00%
Restricted Stock Units (RSUs) [Member] | Equity Grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during period (in shares)			2,559
Shares vested during period (in shares)			2,202
Shares forfeited during period (in shares)			164
Deferred Cash Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation, vesting period (in years)			4 years
Compensation expense related to deferred compensation programs	272,000	878,000	$ 1,154,000	2,718,000
Acquisition Related [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense related to acquisition related awards		629,000	1,237,000	4,626,000
Compensation expense related to deferred cash consideration		(36,000)	301,000	1,663,000
Special Charges [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense Related To Separation Benefits		3,336,000	1,863,000	3,336,000
Cash Payments Related To Separation Benefits		$ 110,000	$ 487,000	$ 110,000
Evercore ISI [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Management Basis EBIT Margin (as a percent)			15.70%
Management Basis EBIT			$ 34,600,000
Class E LP Units [Member] | Evercore ISI [Member] | Vested LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Of LP Units (in units)					710
Class E LP Units [Member] | Evercore ISI [Member] | Unvested LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Of LP Units (in units)					710
Class E LP Units [Member] | Evercore ISI [Member] | Acquisition Related [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense related to acquisition related awards	6,193,000		16,155,000
Class G Interests [Member] | Evercore ISI [Member] | Vested LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Of LP Units (in units)					538
Class G Interests [Member] | Evercore ISI [Member] | Unvested LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Of LP Units (in units)					540
Class H Interests [Member] | Evercore ISI [Member] | Vested LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Of LP Units (in units)					2,044
Class H Interests [Member] | Evercore ISI [Member] | Unvested LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Of LP Units (in units)					2,051
Class G And H Interests [Member] | Evercore ISI [Member] | Acquisition Related [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense related to acquisition related awards	$ 15,657,000		$ 48,970,000