Goodwill and Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Dec. 06, 2019	Nov. 01, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Goodwill and Intangible Assets [Line Items]
Amortization of intangible assets			$ 4,700	$ 3,800	$ 14,489	$ 10,960
Customer Relationships [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets					9 years 10 months 24 days
Trade Name [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets					9 years 1 month 6 days
Core Deposits [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets					3 years 3 months 18 days
Non-Compete Agreements [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets					6 years 1 month 6 days
Investment Banking Backlog [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets					7 years 10 months 24 days
Acquired Technology [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets					1 year 9 months 18 days
MainFirst Bank AG [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Date of acquisition		Jul. 01, 2019
GMP Capital Inc. [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Date of acquisition	Sep. 03, 2019