Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 1,787,651	$ 1,787,651
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	10 years