Loans and Allowance for Loan Losses (Additional Information) (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) loan	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 13,590,000	$ 20,254,000	$ 15,235,000
Financing receivable, allowance for credit losses	24,171,000	23,116,000	21,166,000	$ 21,116,000
Foregone interest	$ 843,000	$ 888,000	$ 586,000
Number of Portfolio Concentration Industries	0
Financing Receivable, Modifications, Number of Contracts	5	6	1
Allowance Related to Troubled Debt Restructurings assigned during period	$ 45,000	$ 1,400,000	$ 27,000
Loans and Leases Receivable, Impaired, Commitment to Lend	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0	0
HPFC Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Individually Evaluated for Impairment		97,000
Financing receivable, allowance for credit losses	451,000	672,000	24,000
Unallocated Financing Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit losses	0	0	0	2,384,000
Residential real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 5,171,000	4,348,000	6,026,000
Term to maturity (years)	30 years
Financing receivable, allowance for credit losses	$ 5,086,000	4,160,000	4,545,000	4,899,000
Financing Receivable in Process of Foreclosure	1,900,000	1,400,000
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans restructured due to credit difficulties that are now performing	5,000,000	4,300,000
Financing Receivables Impaired Troubled Debt Restructuring Non-Performing	1,200,000	1,400,000
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Individually Evaluated for Impairment		7,000	74,000
Financing receivable, allowance for credit losses	233,000	181,000	$ 193,000	$ 281,000
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 500,000	250,000
Number of Months	18
Minimum [Member] | HPFC Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term to maturity (years)	7 years
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Months	24
Maximum [Member] | HPFC Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term to maturity (years)	10 years
Total Loan Portfolio [Member] | Loan Concentration Risk [Member] | Non-Residential Building Operators Industry Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration Risk, Percentage	11.00%
Commercial real estate loans | Loan Concentration Risk [Member] | Non-Residential Building Operators Industry Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration Risk, Percentage	27.00%
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans	1
Loans and Leases Receivable, Impaired, Commitment to Lend	$ 280,000
Commercial loans | Extended Maturity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans restructured due to credit difficulties that are now performing	$ 22,000	$ 47,000
Financing Receivable, Modifications, Number of Contracts	0	6	0
Allowance Related to Troubled Debt Restructurings assigned during period	$ 0	$ 1,400,000	$ 0