Income Taxes - Details of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets, Gross [Abstract]
Depreciation And Amortization	$ 37,912	$ 33,738
Compensation and Benefits	85,567	61,541
Deferred Tax Assets, Operating Lease	58,497	0
Other	20,617	24,720
Total Deferred Tax Assets	343,858	268,186
Deferred Tax Liabilities, Gross [Abstract]
Deferred Tax Liability, Operating Lease	46,682	0
Goodwill, Intangible Assets and Other	19,012	18,873
Total Deferred Tax Liabilities	65,694	18,873
Net Deferred Tax Assets Before Valuation Allowance	278,164	249,313
Valuation Allowance	(9,573)	(8,221)
Net Deferred Tax Assets	268,591	241,092
Tax Receivable Agreement [Member]
Deferred Tax Assets, Gross [Abstract]
Step up in tax basis due to the exchange of LP Units for Class A Shares	99,979	111,108
Without Tax Receivable Agreement [Member]
Deferred Tax Assets, Gross [Abstract]
Step up in tax basis due to the exchange of LP Units for Class A Shares	$ 41,286	$ 37,079