Loans and Allowance for Loan Losses (Activity in Allowance for Loan Losses by Portfolio Segment) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		$ 24,712,000	$ 24,171,000	$ 23,116,000
Loans charged off		(2,713,000)	(2,248,000)	(2,468,000)
Recoveries		310,000	1,944,000	497,000
Provision (credit)	[1]	2,862,000	845,000	3,026,000
Ending balance		25,171,000	24,712,000	24,171,000
Ending Balance: Individually evaluated for impairment		463,000	824,000	2,009,000
Ending Balance: Collectively evaluated for impairment		24,708,000	23,888,000	22,162,000
Ending Balance: Individually evaluated for impairment		4,478,000	6,926,000	13,590,000
Ending Balance: Collectively evaluated for impairment		3,090,545,000	3,019,296,000	2,768,849,000
Total loan balances		3,095,023,000	3,026,222,000	2,782,439,000
Reserve for unfunded commitments		21,000	22,000	20,000
Residential real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		6,071,000	5,086,000	4,160,000
Loans charged off		(462,000)	(173,000)	(482,000)
Recoveries		16,000	90,000	30,000
Provision (credit)	[1]	217,000	1,068,000	1,378,000
Ending balance		5,842,000	6,071,000	5,086,000
Ending Balance: Individually evaluated for impairment		364,000	586,000	568,000
Ending Balance: Collectively evaluated for impairment		5,478,000	5,485,000	4,518,000
Ending Balance: Individually evaluated for impairment		3,384,000	4,762,000	5,171,000
Ending Balance: Collectively evaluated for impairment		1,066,990,000	988,104,000	853,198,000
Total loan balances		1,070,374,000	992,866,000	858,369,000
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		11,654,000	11,863,000	12,154,000
Loans charged off		(300,000)	(512,000)	(124,000)
Recoveries		49,000	28,000	141,000
Provision (credit)	[1]	1,011,000	275,000	(308,000)
Ending balance		12,414,000	11,654,000	11,863,000
Ending Balance: Individually evaluated for impairment		30,000	23,000	1,441,000
Ending Balance: Collectively evaluated for impairment		12,384,000	11,631,000	10,422,000
Ending Balance: Individually evaluated for impairment		402,000	930,000	6,199,000
Ending Balance: Collectively evaluated for impairment		1,242,995,000	1,268,603,000	1,157,824,000
Total loan balances		1,243,397,000	1,269,533,000	1,164,023,000
Commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		3,620,000	4,171,000	3,755,000
Loans charged off		(1,167,000)	(736,000)	(1,014,000)
Recoveries		225,000	1,770,000	301,000
Provision (credit)	[1]	1,091,000	(1,585,000)	1,129,000
Ending balance		3,769,000	3,620,000	4,171,000
Ending Balance: Individually evaluated for impairment			53,000
Ending Balance: Collectively evaluated for impairment		3,769,000	3,567,000	4,171,000
Ending Balance: Individually evaluated for impairment		319,000	786,000	1,791,000
Ending Balance: Collectively evaluated for impairment		420,789,000	380,994,000	371,609,000
Total loan balances		421,108,000	381,780,000	373,400,000
Home equity
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		2,796,000	2,367,000	2,194,000
Loans charged off		(412,000)	(476,000)	(434,000)
Recoveries		1,000	44,000	2,000
Provision (credit)	[1]	38,000	861,000	605,000
Ending balance		2,423,000	2,796,000	2,367,000
Ending Balance: Individually evaluated for impairment		69,000	162,000
Ending Balance: Collectively evaluated for impairment		2,354,000	2,634,000	2,367,000
Ending Balance: Individually evaluated for impairment		373,000	442,000	429,000
Ending Balance: Collectively evaluated for impairment		312,406,000	327,321,000	322,949,000
Total loan balances		312,779,000	327,763,000	323,378,000
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		234,000	233,000	181,000
Loans charged off		(301,000)	(96,000)	(124,000)
Recoveries		19,000	11,000	17,000
Provision (credit)	[1]	555,000	86,000	159,000
Ending balance		507,000	234,000	233,000
Ending Balance: Collectively evaluated for impairment		507,000	234,000	233,000
Ending Balance: Individually evaluated for impairment			6,000
Ending Balance: Collectively evaluated for impairment		25,772,000	20,618,000	18,149,000
Total loan balances		25,772,000	20,624,000	18,149,000
HPFC Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		337,000	451,000	672,000
Loans charged off		(71,000)	(255,000)	(290,000)
Recoveries			1,000	6,000
Provision (credit)	[1]	(50,000)	140,000	63,000
Ending balance		216,000	337,000	451,000
Ending Balance: Collectively evaluated for impairment		216,000	337,000	451,000
Ending Balance: Collectively evaluated for impairment		21,593,000	33,656,000	45,120,000
Total loan balances		$ 21,593,000	$ 33,656,000	$ 45,120,000

[1] (1) The provision (credit) for loan losses excludes any impact for the change in the reserve for unfunded commitments, which represents management's estimate of the amount required to reflect the probable inherent losses on outstanding letters of credit and unused lines of credit. The reserve for unfunded commitments was presented within accrued interest and other liabilities on the consolidated statements of condition. At December 31, 2019, 2018, and 2017, the reserve for unfunded commitments was $21,000, $22,000 and $20,000, respectively.