ALLOWANCE FOR LOAN LOSSES: (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Allowance for Loan Losses:
Beginning balance	$ 19,946		$ 18,839		$ 20,068
Provision for loan losses	3,300	[1]	4,700	[2]	4,385	[3]
Loans charged -off	(8,949)		(8,528)		(9,450)
Recoveries	4,476		4,935		3,836
Ending Balance	18,773		19,946		18,839
Increase in provision for decrease in FDIC indemnification asset					687
Commercial
Allowance for Loan Losses:
Beginning balance	11,482		10,915		12,450
Provision for loan losses	(755)	[1]	990	[2]	1,053	[3]
Loans charged -off	(2,659)		(2,852)		(3,522)
Recoveries	1,663		2,429		934
Ending Balance	9,731		11,482		10,915
Residential
Allowance for Loan Losses:
Beginning balance	1,834		1,374		1,585
Provision for loan losses	54	[1]	874	[2]	134	[3]
Loans charged -off	(1,011)		(866)		(1,143)
Recoveries	676		452		798
Ending Balance	1,553		1,834		1,374
Consumer
Allowance for Loan Losses:
Beginning balance	4,945		4,370		3,650
Provision for loan losses	3,964	[1]	3,331	[2]	3,401	[3]
Loans charged -off	(5,279)		(4,810)		(4,785)
Recoveries	2,137		2,054		2,104
Ending Balance	5,767		4,945		4,370
Unallocated
Allowance for Loan Losses:
Beginning balance	1,685		2,180		2,383
Provision for loan losses	37	[1]	(495)	[2]	(203)	[3]
Loans charged -off	0		0		0
Recoveries	0		0		0
Ending Balance	$ 1,722		$ 1,685		$ 2,180

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[2] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmQ5YjBmZmM0NjM1MTQ4YjNhMDkyM2NlZDZlMGU0ZjFmfFRleHRTZWxlY3Rpb246MkYzRDYxQUUyNDY3NTNGNDlDRDZENEM0Nzk3Mzk4QjQM}

[3] Provision before increase of $687 thousand in 2014 for decrease in FDIC indemnification asset