Acquisitions - Schedule of Final Purchase Price of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Jul. 01, 2015
ASSETS
Goodwill	$ 49,600	$ 49,600
Peoples Bancorp Inc [Member]
ASSETS
Cash and due from banks			$ 205,054
Investment securities, held to maturity			2,038
Total loans			224,359
Premises and equipment, net			5,524
FRB and FHLB stock			2,743
Goodwill			21,424
Core deposit intangible			4,394
Interest receivable			1,279
Cash value of life insurance			13,898
Other assets			4,364
Total assets purchased			485,077
Common shares issued			55,506
Cash paid			22,641
Total estimated purchase price			78,147
Deposits
Non-interest bearing			28,251
NOW accounts			65,771
Savings and money market			125,176
Certificates of deposits			131,889
Total deposits			351,087
Borrowings			48,884
Interest payable			21
Other liabilities			6,938
Total liabilities assumed			406,930
Peoples Bancorp Inc [Member] | Residential Mortgage [Member]
ASSETS
Total loans			137,331
Peoples Bancorp Inc [Member] | Commercial [Member]
ASSETS
Total loans			67,435
Peoples Bancorp Inc [Member] | Consumer [Member]
ASSETS
Total loans			$ 19,593