EMPLOYEE BENEFIT PLANS: (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Severance pay details
Accrued severance liability	$ 13,418,000	$ 11,821,000
Severance assets	10,630,000	8,907,000
Pretax savings plan under 401 (k) of the Internal Revenue Code
Severance payments
Employer contribution limit per calendar year (as a percent of base salary)	4.00%
Severance pay details
Defined pension contribution plan expenses	800,000	500,000	400,000
Israeli postemployment benefit plan
Severance pay details
Accrued severance liability	13,418,000	11,821,000
Severance assets	10,630,000	8,907,000
Unfunded portion	2,788,000	2,914,000
Company's contribution as a percentage of employee monthly salary to insurance policy or pension fund	8.33%
Company's contribution as a percentage of employee monthly salary to pension contribution plan	6.00%
Additional severance payments to employee	0
Severance pay expenses	6,100,000	4,300,000	3,900,000
Defined pension contribution plan expenses	$ 4,500,000	$ 3,200,000	$ 2,500,000