Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2016 USD ($) State Branch Segment	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Assets managed by the Company	$ 767,000
Assets	$ 2,450,273	$ 2,462,276
Number of business segment \| Segment	1
First Community Bank
Summary Of Significant Accounting Policies [Line Items]
Number of operating branches \| Branch	45
Number of states the company provides services \| State	4

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration