RETIREMENT PLANS: (Details 4)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets (percent)	100.00%	100.00%
Employee Stock Ownership Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets (percent)	100.00%	100.00%
Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets (percent)	3.00%	2.00%
Other Securities [Member] | Employee Stock Ownership Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets (percent)	1.00%	1.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range minimum (percent)	40.00%
Target plan asset allocations range maximum (percent)	65.00%
Percentage of plan assets (percent)	59.00%	64.00%
Equity Securities | Employee Stock Ownership Plan
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range minimum (percent)	95.00%
Target plan asset allocations range maximum (percent)	99.00%
Percentage of plan assets (percent)	99.00%	99.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range minimum (percent)	35.00%
Target plan asset allocations range maximum (percent)	60.00%
Percentage of plan assets (percent)	38.00%	34.00%
Debt securities | Employee Stock Ownership Plan
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range minimum (percent)	0.00%
Target plan asset allocations range maximum (percent)	0.00%
Percentage of plan assets (percent)	0.00%	0.00%
Other Security Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range minimum (percent)	0.00%
Target plan asset allocations range maximum (percent)	10.00%
Other Security Investments [Member] | Employee Stock Ownership Plan
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range minimum (percent)	0.00%
Target plan asset allocations range maximum (percent)	5.00%