Share-Based and Other Deferred Compensation (Details) $ / shares in Units, $ in Thousands		1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 15, 2019 shares	Jun. 30, 2019 USD ($) shares	Nov. 30, 2017 USD ($) shares	Jul. 31, 2017 vote shares	Nov. 30, 2016 USD ($) tranche Number_Of_Anniversaries shares	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($) shares	Sep. 30, 2019 USD ($) payment_installment Installments $ / shares shares	Sep. 30, 2018 USD ($) shares	Dec. 31, 2016 shares	Mar. 31, 2019 USD ($)	Dec. 31, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement Compensation Expense						$ 20,688	$ 13,147	$ 73,456	$ 41,328
Severance Costs						2,762	538	7,575	7,022
Cash Payments Related to Separation Benefits						$ 1,204	$ 763	$ 4,461	$ 6,636
LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited Partnership Units Convertible Conversion Ratio					1			1
2016 Stock Incentive Plan [Member] | Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Additional Shares Authorized (in shares) | shares										10,000,000
Number of Shares Available for Grant (in shares) | shares						2,869,000	5,367,000	2,869,000	5,367,000
Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement Compensation Expense						$ 8,302	$ 7,007	$ 24,928	$ 21,082
Long Term Incentive Plan Performance Period (in years)								4 years
Number of Payment Installments | payment_installment								3
Deferred Compensation Arrangement with Individual, Distribution Paid								$ 19,516	4,532
Long Term Incentive Plan [Member] | Other Noncurrent Liabilities [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement with Individual, Recorded Liability						90,258		90,258
Class J LP Units [Member] | Acquisition Related [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Vested During Period (in shares) | shares	632,000
Class I-P Units [Member] | Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense						1,164	1,164	3,455	3,352
Grant of I-P Units (in units) | shares					400,000
Retirement Notice Requirement					1 year
Number of Tranches of Class I-P Units | tranche					2
Number of Class I-P Units in Each Tranche (in units) | shares					200,000
Number of Consecutive Trading Days Required for Class I-P Units to Exceed Thresholds					20 days
Grant of I-P Units, Fair Value of Award					$ 24,412
Class K-P Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense						1,277	302	$ 1,911	897
Limited Partnership Units Convertible Conversion Ratio								1
Grant of K-P Units (in units) | shares		220,000	64,000
K-P Units to be Granted Upon Achievement of Benchmarks (in units) | shares			16,000
Grant of K-P Units, Fair Value of Award		$ 5,771	$ 6,250
Restricted Stock Units (RSUs) [Member] | 2016 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued During Period (in shares) | shares								2,564,000
Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares								$ 91.24
Restricted Stock Units (RSUs) [Member] | 2016 Stock Incentive Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares								72.11
Restricted Stock Units (RSUs) [Member] | 2016 Stock Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares								$ 96.22
Restricted Stock Units (RSUs) [Member] | 2006 and 2016 Stock Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense						50,152	41,679	$ 162,296	130,785
Shares Vested During Period (in shares) | shares								2,412,000
Shares Forfeited During Period (in shares) | shares								87,000
Deferred Cash Compensation Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation, Vesting Period (in years)								4 years
Deferred Compensation Arrangement with Individual, Cash Award Granted, Amount											$ 93,366
Restricted Cash Award [Member] | Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Retirement Notice Requirement					6 months
Deferred Compensation Arrangement with Individual, Cash Award Granted, Amount					$ 35,000
Deferred Compensation Arrangement With Individual Cash Award Tranche One Vesting Amount					11,000
Deferred Compensation Arrangement With Individual Cash Award Tranche Two Vesting Amount					$ 6,000
Awards Vesting Period | Number_Of_Anniversaries					4
Restricted Cash Award [Member] | Minimum [Member] | Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement with Individual, Cash Award Granted, Amount					$ 8,750
Restricted Cash Award [Member] | Maximum [Member] | Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement with Individual, Cash Award Granted, Amount					$ 35,000
Other Deferred Cash [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement with Individual, Cash Award Granted, Amount												$ 29,500
Awards Vesting Period | Installments								5
Long Term Incentive Plan [Member] | 2017 Long-term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement with Individual, Compensation Cost Not Yet Recognized						69,569		$ 69,569
Employee Loans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement Compensation Expense						6,631	5,701	15,976	13,810
Deferred Compensation Arrangement with Individual, Recorded Liability						33,392		$ 33,392
Requisite Service Period (in years)								1 year
Maximum Contractual Term (in years)								5 years
Evercore ISI [Member] | Class H LP Interests [Member] | Acquisition Related [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Units Outstanding (in units) | shares				4,148,000
Evercore ISI [Member] | Class J LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Number of Votes | vote				1
Evercore ISI [Member] | Class J LP Units [Member] | Class B [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, New Issues | shares				1
Evercore ISI [Member] | Class J LP Units [Member] | Acquisition Related [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense						$ 4,527	3,741	$ 12,276	11,313
Evercore ISI [Member] | Vested LP Units [Member] | Class J LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant of LP Units (in units) | shares				1,012,000
Evercore ISI [Member] | Vested LP Units [Member] | Class J LP Units [Member] | Subject to Continued Employment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant of LP Units (in units) | shares				963,000
Evercore ISI [Member] | Unvested LP Units [Member] | Class J LP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant of LP Units (in units) | shares				938,000
Share-based Compensation Award, Tranche One [Member] | Class K-P Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant of K-P Units (in units) | shares		120,000
Share-based Compensation Award, Tranche Two [Member] | Class K-P Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant of K-P Units (in units) | shares		100,000
Special Charges [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Severance Costs							$ 781		$ 2,024