Goodwill and Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 02, 2019	Dec. 31, 2018
Schedule of Goodwill and Intangible Assets [Line Items]
Goodwill	$ 1,056,357		$ 1,056,357			$ 1,034,679
Amortization of intangible assets	$ 3,500	$ 3,000	$ 7,140	$ 5,740
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 2 months 12 days
Core Deposits [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets			4 years 7 months 6 days
Non-Compete Agreements [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Weighted-average remaining lives of intangible assets			9 years 6 months
First Empire [Member]
Schedule of Goodwill and Intangible Assets [Line Items]
Goodwill					$ 22,500