DERIVATIVES AND HEDGING ACTIVITIES: (Details)			12 Months Ended
	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2012 Foreign currency forward contract USD ($)	Dec. 31, 2011 Foreign currency forward contract USD ($)	Dec. 31, 2010 Foreign currency forward contract USD ($)	Dec. 31, 2012 Foreign currency forward contract ILS	Dec. 31, 2011 Foreign currency forward contract ILS
Derivatives and Hedging Activities
Future operating expenses hedged			$ 58,900,000	$ 43,700,000		219,900,000	167,100,000
Period over which operating expenses hedged will be expensed			12 months
Derivative Assets Reported in Other Current Assets
Foreign exchange contracts designated as cash flow hedges			2,942,000
Total derivatives designated as hedging instruments	2,942,000
Derivative Liabilities Reported in Other Current Liabilities
Foreign exchange contracts designated as cash flow hedges				1,149,000
Total derivatives designated as hedging instruments		1,149,000
Balance of derivative contracts designated as cash flow hedges and their impact on OCI
Balance at the beginning of the period			(1,149,000)
Amount of gain recognized in OCI (effective portion)			3,198,000
Amount of loss reclassified from OCI to income (effective portion)			893,000
Balance at the end of the period			2,942,000	(1,149,000)
Expected time to realize the accumulated OCI balance related to foreign exchange contracts			12 months
Impact of derivative contracts on total operating expense
Gain (loss) on foreign exchange contracts designated as cash flow hedges			$ (893,000)	$ 1,223,000	$ 563,000