Goodwill And Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 01, 2018	Aug. 31, 2018	Mar. 19, 2018
Schedule of Goodwill and Intangible Assets [Line Items]
Goodwill	$ 1,034,679	$ 968,834
Amortization of intangible assets	12,557	12,135	$ 14,427
Global Wealth Management [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Goodwill	340,395	$ 276,477
Amortization of intangible assets	$ 5,773
Core Deposits [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets	4 years 10 months 24 days
Customer Relationships [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets	10 years 6 months
Trade Name [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets	9 years 7 months 6 days
Non-Compete Agreements [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets	8 years 9 months 18 days
Ziegler [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Goodwill						$ 19,000
Ziegler [Member] | Customer Relationships and Non-Compete Agreements [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Identifiable intangible assets						$ 9,500
Business Bancshares, Inc. [Member] | Global Wealth Management [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Goodwill					$ 38,400
Business Bancshares, Inc. [Member] | Core Deposits [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Identifiable intangible assets					$ 8,600
Rand & Associates [Member] | Global Wealth Management [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Goodwill				$ 8,300
Rand & Associates [Member] | Customer Relationships [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Identifiable intangible assets				$ 4,600