Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Section 45
-Paragraph 1
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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Section S99
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Short-term Borrowings (Narrative) (Detail) - USD ($)	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Short term borrowings	$ 21,468,000		$ 31,596,000
Current borrowing available		$ 404,204,000
Federal Funds Purchased [Member]
Short-term Debt [Line Items]
Short term borrowings		0	$ 31,596,000
Short-term debt, weighted average interest rate			0.40%
Correspondent Banks [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity		$ 15,000,000