Goodwill And Other Intangible Assets (Goodwill Assets by Business Segment) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 501,884
Goodwill Acquired	10,229
Impairment Loss	0
Goodwill Adjustments	(616)
Ending balance	511,497
Community banking
Goodwill [Roll Forward]
Beginning balance	429,520
Goodwill Acquired	10,229
Impairment Loss	0
Goodwill Adjustments	0
Ending balance	439,749
Specialty finance
Goodwill [Roll Forward]
Beginning balance	40,250
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	(616)
Ending balance	39,634
Wealth management
Goodwill [Roll Forward]
Beginning balance	32,114
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	0
Ending balance	$ 32,114