Goodwill and Intangible Assets (Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 259,102	$ 200,225
Accumulated Amortization	97,329	80,570
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	198,248	160,745
Accumulated Amortization	75,987	65,254
Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	28,123	26,831
Accumulated Amortization	13,649	11,755
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	8,615	8,615
Accumulated Amortization	2,985	816
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	8,319	2,603
Accumulated Amortization	2,828	1,452
Investment Banking Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	4,245	1,431
Accumulated Amortization	1,787	$ 1,293
Acquired Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	840
Accumulated Amortization	93
Estimated GMP Capital Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 10,712