Acquisitions (Narrative) (Details) - USD ($) $ in Thousands, shares in Millions					12 Months Ended
	Jul. 01, 2022	Nov. 01, 2021	Sep. 03, 2019	Jul. 01, 2019	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Goodwill						$ 1,326,548	$ 1,306,892
Institutional Group [Member]
Business Acquisition [Line Items]
Goodwill						991,539	971,883
Vining Sparks [Member]
Business Acquisition [Line Items]
Date of acquisition		Nov. 01, 2021
Shares issued as part of the consideration		1.2
Payments to Acquire Intangible Assets		$ 25,400
Vining Sparks [Member] | Institutional Group [Member]
Business Acquisition [Line Items]
Goodwill		$ 127,000
ACXIT Capital Partners [Member]
Business Acquisition [Line Items]
Date of acquisition	Jul. 01, 2022
Payments to Acquire Intangible Assets	$ 5,000
Period of contingent consideration	1 year
Liability for earn-out payments						5,200
ACXIT Capital Partners [Member] | Institutional Group [Member]
Business Acquisition [Line Items]
Goodwill	$ 17,300
B&F Capital Markets, Inc. [Member]
Business Acquisition [Line Items]
Date of acquisition			Sep. 03, 2019
Period of contingent consideration			5 years
Liability for earn-out payments						5,200	10,500
Mooreland Partners [Member]
Business Acquisition [Line Items]
Date of acquisition					Jul. 01, 2019
Period of contingent consideration				3 years
Liability for earn-out payments						$ 5,500	18,500
Additional liability for earn-out payments							$ 13,500