EMPLOYEE BENEFIT PLANS: (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
EMPLOYEE BENEFIT PLANS:
Employer contribution limit per calendar year (as a percent of base salary)	4.00%
Expenses related to employer contributions	$ 522,000	$ 422,000	$ 286,000
Severance payments
Defined pension contribution plan expenses	522,000	422,000	286,000
Severance pay details
Accrued severance liability	11,821,000	10,433,000
Severance assets	8,907,000	7,767,000
Israeli postemployment benefit plan
EMPLOYEE BENEFIT PLANS:
Expenses related to employer contributions	3,200,000	2,500,000	1,300,000
Severance payments
Defined pension contribution plan expenses	3,200,000	2,500,000	1,300,000
Severance pay expenses	4,300,000	3,900,000	2,200,000
Severance pay details
Accrued severance liability	11,821,000	10,433,000
Severance assets	8,907,000	7,767,000
Unfunded portion	$ 2,914,000	$ 2,666,000
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%