Revenue and Accounts Receivable - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Investment Banking [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer	$ 642,246	$ 659,587	$ 1,354,014	$ 1,304,288
Investment Banking [Member] | Advisory Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer	576,245	560,814	1,200,809	1,072,732
Investment Banking [Member] | Underwriting Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer	13,516	48,048	49,822	127,305
Investment Banking [Member] | Commissions and Related Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer	52,485	50,725	103,383	104,251
Investment Management [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer	15,968	16,183	33,083	31,132
Investment Management [Member] | Wealth Management [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer	$ 15,968	$ 16,183	$ 33,083	$ 31,132