FOREIGN OPERATIONS: (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Financial information by geographic area
Revenues	$ 224,867	$ 223,312	$ 217,267	$ 214,801	$ 224,655	$ 221,193	$ 207,345	$ 196,895	$ 880,247	$ 850,088	$ 804,911
Long-lived assets excluding financial instruments	866,019				773,839				866,019	773,839
United States
Financial information by geographic area
Revenues									807,387	770,043	709,133
Long-lived assets excluding financial instruments	843,127				748,123				843,127	748,123
Foreign
Financial information by geographic area
Revenues									72,860	80,045	95,778
Long-lived assets excluding financial instruments	22,892				25,716				22,892	25,716
Europe
Financial information by geographic area
Revenues									55,427	52,562	59,958
Long-lived assets excluding financial instruments	9,096				11,899				9,096	11,899
APAC
Financial information by geographic area
Revenues									17,433	25,138	32,658
Long-lived assets excluding financial instruments	$ 13,796				$ 13,817				$ 13,796	13,817
Other
Financial information by geographic area
Revenues										$ 2,345	$ 3,162