Goodwill and Other Intangible Assets (Schedule of Other Intangible Assets) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 45,906	$ 50,762
Accumulated Amortization	(37,106)	(38,637)
Net Intangible Assets	8,800	12,125
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	39,410	44,266
Accumulated Amortization	(32,324)	(34,591)
Net Intangible Assets	7,086	9,675
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	5,771	5,771
Accumulated Amortization	(4,214)	(3,643)
Net Intangible Assets	1,557	2,128
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	725	725
Accumulated Amortization	(568)	(403)
Net Intangible Assets	$ 157	$ 322