Goodwill and Other Intangible Assets (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Amortization expense related to intangible assets	$ 2,429	$ 3,325	$ 3,520
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets estimated lives, years	5 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets estimated lives, years	10 years
WNB Bancshares, Inc. [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			118,000
Finite-lived Intangible Assets Acquired			$ 9,300
Insurance [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period	$ 284
Finite-lived Intangible Assets Acquired	$ 405