COMMITMENTS AND CONTINGENCIES: (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Leases
Rent expense of office space and motor vehicles under operating leases	$ 6,800,000	$ 6,600,000	$ 2,800,000
Property and equipment, gross under capital lease agreements	4,100,000	600,000
Total future minimum lease payments under non-cancelable operating and capital leases	52,700,000
Accumulated amortization for assets under capital lease agreements	300,000	100,000
Future minimum payments under non-cancelable capital leases
2013	1,268,000
2014	1,260,000
2015	1,114,000
2016	503,000
Total minimum lease payments	4,145,000
Less: Amount representing interest	(57,000)
Present value of capital lease obligations	4,088,000
Less: Current portion	(1,253,000)	(299,000)
Long-term portion of capital lease obligations	2,835,000	279,000
Future minimum payments under non-cancelable operating leases
2013	13,003,000
2014	10,536,000
2015	6,177,000
2016	4,750,000
2017 and beyond	14,436,000
Total minimum lease payments	48,902,000
Purchase commitments
Amount of non-cancelable purchase commitments	59,000,000
Amount of non-cancelable purchase commitments expected to be paid within one year	57,900,000
Amount of non-cancelable purchase commitments expected to be paid within two years and beyond	$ 1,100,000