GOODWILL AND INTANGIBLE ASSETS: - Amounts allocated to intangible assets from acquisitions (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 121,314	$ 119,114	$ 78,316
Accumulated amortization	(76,775)	(52,855)	(34,213)
Total finite-lived intangible assets, net	44,539	66,259	44,103
Developed technology (Software, net)
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	54,150	52,150	42,850
Accumulated amortization	(43,533)	(29,775)	(17,950)
Total finite-lived intangible assets, net	10,617	22,375	24,900
Trade names
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	43,364	43,164	35,466
Accumulated amortization	(27,953)	(21,702)	(16,263)
Total finite-lived intangible assets, net	15,411	21,462	19,203
Publisher relationship
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	23,800	23,800	0
Accumulated amortization	(5,289)	(1,378)	0
Total finite-lived intangible assets, net	18,511	$ 22,422	$ 0
Marketing Services
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	11
Marketing Services | Trade names
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	11
Audience Solutions
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	911
Audience Solutions | Developed technology (Software, net)
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	600
Audience Solutions | Trade names
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	311
Connectivity
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	43,617
Connectivity | Developed technology (Software, net)
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	10,017
Connectivity | Trade names
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	15,089
Connectivity | Publisher relationship
Finite-Lived Intangible Assets [Line Items]
Total finite-lived intangible assets, net	$ 18,511