RETIREMENT PLANS: (Details 1) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ 4,264	$ 5,495
Change in benefit obligation:
Benefit obligation at January 1	98,096	93,233
Service cost	1,388	1,432	$ 1,882
Interest cost	3,194	3,621	3,729
Actuarial (gain) loss	(10,618)	5,305
Benefits paid	(4,264)	(5,495)
Benefit obligation at December 31	87,796	98,096	93,233
Reconciliation of fair value of plan assets:
Fair value of plan assets at January 1	71,449	70,132
Actual return on plan assets	(5,464)	3,879
Employer contributions	2,614	2,933
Fair value of plan assets at December 31	64,335	71,449	$ 70,132
Funded status at December 31 (plan assets less benefit obligation)	$ (23,461)	$ (26,647)

No definition available.

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Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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