ALLOWANCE FOR LOAN LOSSES: (Details 1) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Ending Balance Attributable to Loans
Individually evaluated for impairment	$ 331	$ 1,159
Collectively evaluated for impairment	18,442	18,600
BALANCE AT END OF YEAR	18,773	19,946	$ 18,839	$ 20,068
Loans
Individually evaluated for impairment	8,600	9,725
Collectively evaluated for impairment	1,831,594	1,754,444
BALANCE AT END OF YEAR	1,845,040	1,769,790
Commercial
Ending Balance Attributable to Loans
Individually evaluated for impairment	242	953
Collectively evaluated for impairment	9,489	10,342
BALANCE AT END OF YEAR	9,731	11,482	10,915	12,450
Loans
Individually evaluated for impairment	8,051	8,823
Collectively evaluated for impairment	1,101,269	1,037,086
BALANCE AT END OF YEAR	1,112,735	1,050,001
Residential
Ending Balance Attributable to Loans
Individually evaluated for impairment	89	206
Collectively evaluated for impairment	1,464	1,628
BALANCE AT END OF YEAR	1,553	1,834	1,374	1,585
Loans
Individually evaluated for impairment	549	902
Collectively evaluated for impairment	423,099	443,224
BALANCE AT END OF YEAR	425,079	445,655
Consumer
Ending Balance Attributable to Loans
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	5,767	4,945
BALANCE AT END OF YEAR	5,767	4,945	4,370	3,650
Loans
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	307,226	274,134
BALANCE AT END OF YEAR	307,226	274,134
Unallocated
Ending Balance Attributable to Loans
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,722	1,685
BALANCE AT END OF YEAR	1,722	1,685	$ 2,180	$ 2,383
Acquired with deteriorated credit quality
Ending Balance Attributable to Loans
Acquired with deteriorated credit quality	0	187
Loans
Acquired with deteriorated credit quality	4,846	5,621
Acquired with deteriorated credit quality | Commercial
Ending Balance Attributable to Loans
Acquired with deteriorated credit quality	0	187
Loans
Acquired with deteriorated credit quality	3,415	4,092
Acquired with deteriorated credit quality | Residential
Ending Balance Attributable to Loans
Acquired with deteriorated credit quality	0	0
Loans
Acquired with deteriorated credit quality	1,431	1,529
Acquired with deteriorated credit quality | Consumer
Ending Balance Attributable to Loans
Acquired with deteriorated credit quality	0	0
Loans
Acquired with deteriorated credit quality	0	0
Acquired with deteriorated credit quality | Unallocated
Ending Balance Attributable to Loans
Acquired with deteriorated credit quality	$ 0	$ 0