Business Combinations (Narrative) (Detail) $ in Thousands					3 Months Ended	6 Months Ended
	Feb. 14, 2017 USD ($)	Nov. 18, 2016 USD ($) locations	Aug. 19, 2016 USD ($)	Mar. 31, 2016 USD ($) locations	Jun. 30, 2017 USD ($)	Jun. 30, 2017 USD ($) financial_institution
Business Acquisition [Line Items]
Number of locations | locations		2
Goodwill recorded on acquisition						$ 999
FDIC loss sharing percentage on purchased loans, OREO, and certain other assets						80.00%
Reduction in estimated loss share liability					$ (4,900)
First Community Financial Corporatiion (FCFC)
Business Acquisition [Line Items]
Effective date of acquisition		Nov. 18, 2016
Assets acquired		$ 187,200
Loans acquired		79,500
Assumed deposits		150,300
Goodwill recorded on acquisition		$ 13,000
GE Capital Franchise Finance
Business Acquisition [Line Items]
Effective date of acquisition			Aug. 19, 2016
Loans acquired			$ 561,400
Generations Bancorp Inc.
Business Acquisition [Line Items]
Effective date of acquisition				Mar. 31, 2016
Number of locations | locations				1
Assets acquired				$ 134,200
Loans acquired				67,400
Assumed deposits				100,200
Goodwill recorded on acquisition				$ 11,500
FDIC Assisted
Business Acquisition [Line Items]
Number of FDIC assisted banks acquired | financial_institution						9
American Homestead Mortgage, LLC (AHM)
Business Acquisition [Line Items]
Goodwill recorded on acquisition	$ 999