ALLOWANCE FOR LOAN LOSSES: (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Allowance for Loan Losses:
Beginning balance	$ 20,436		$ 19,909		$ 18,773
Provision for loan losses	4,700	[1]	5,768	[2]	5,295	[3]
Loans charged -off	(10,673)		(8,831)		(8,762)
Recoveries	5,480		3,590		4,603
Ending Balance	19,943		20,436		19,909
Commercial
Allowance for Loan Losses:
Beginning balance	9,848		10,281		9,731
Provision for loan losses	621	[1]	83	[2]	745	[3]
Loans charged -off	(2,616)		(1,122)		(1,572)
Recoveries	1,092		606		1,377
Ending Balance	8,945		9,848		10,281
Residential
Allowance for Loan Losses:
Beginning balance	1,313		1,455		1,553
Provision for loan losses	(321)	[1]	60	[2]	(179)	[3]
Loans charged -off	(1,050)		(841)		(761)
Recoveries	1,360		639		842
Ending Balance	1,302		1,313		1,455
Consumer
Allowance for Loan Losses:
Beginning balance	7,481		6,709		5,767
Provision for loan losses	4,802	[1]	5,295	[2]	4,987	[3]
Loans charged -off	(7,007)		(6,868)		(6,429)
Recoveries	3,028		2,345		2,384
Ending Balance	8,304		7,481		6,709
Unallocated
Allowance for Loan Losses:
Beginning balance	1,794		1,464		1,722
Provision for loan losses	(402)	[1]	330	[2]	(258)	[3]
Loans charged -off	0		0		0
Recoveries	0		0		0
Ending Balance	$ 1,392		$ 1,794		$ 1,464

[1] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM1MDQyYmQ4NWM2ZjQ1ZWM5MjJhM2YwYTIzZDc1YzRmfFRleHRTZWxlY3Rpb246QkQxQTJBQjY0NjMwRTUyNTY1MzQyNEI4QUU0NTY3QzYM}

[2] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM1MDQyYmQ4NWM2ZjQ1ZWM5MjJhM2YwYTIzZDc1YzRmfFRleHRTZWxlY3Rpb246NDk4QzNBN0EzMEVDM0FDNzBEQzQyNEI4QUU0NTJEQTcM}

[3] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM1MDQyYmQ4NWM2ZjQ1ZWM5MjJhM2YwYTIzZDc1YzRmfFRleHRTZWxlY3Rpb246MzA5NzRFNkU3NTRGNjlGOTdGNzUyNEI4QUU0NUIyQzQM}