RETIREMENT PLANS: (Details 5) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 60,602	$ 62,565	$ 67,233
Quoted Prices in Active Markets for Identical Assets - Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46,338	47,320
Significant Other Observable Inputs - Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,264	15,245
Significant Observable Inputs - Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44,052	44,732
Equity Securities | Quoted Prices in Active Markets for Identical Assets - Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44,052	44,732
Equity Securities | Significant Other Observable Inputs - Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity Securities | Significant Observable Inputs - Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,264	15,245
Debt securities | Quoted Prices in Active Markets for Identical Assets - Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Debt securities | Significant Other Observable Inputs - Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,264	15,245
Debt securities | Significant Observable Inputs - Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Investment Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,286	2,588
Investment Funds | Quoted Prices in Active Markets for Identical Assets - Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,286	2,588
Investment Funds | Significant Other Observable Inputs - Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Investment Funds | Significant Observable Inputs - Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0