Goodwill And Other Intangible Assets (Summary of Intangible Assets) (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets, net	$ 21,414	$ 17,621	$ 19,546
Community banking
Finite-Lived Intangible Assets [Line Items]
Total net carrying amount	15,946	11,845	13,640
Trademark | Community banking
Finite-Lived Intangible Assets [Line Items]
Carrying amount	5,800	0	0
Core deposit intangibles | Community banking
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	37,272	37,272	37,272
Accumulated amortization	(27,126)	(25,427)	(23,632)
Net carrying amount	10,146	11,845	13,640
Customer list intangibles | Specialty finance
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,964	1,972	1,800
Accumulated amortization	(1,373)	(1,298)	(1,221)
Net carrying amount	591	674	579
Customer list and other intangibles | Wealth management
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	7,940	7,940	7,940
Accumulated amortization	(3,063)	(2,838)	(2,613)
Net carrying amount	$ 4,877	$ 5,102	$ 5,327