GOODWILL AND INTANGIBLE ASSETS: (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Goodwill
Goodwill at the beginning of year	$ 592,731	$ 492,745
Impact email disposition (see note 4)		(5,684)
Purchase accounting adjustments	(21)	18
Change in foreign currency translation adjustment	25	(18)
Goodwill at the end of year	595,995	592,731
Accumulated impairment losses	$ 120,100	120,100
Minimum
Goodwill
Amortization period	2 years
Maximum
Goodwill
Amortization period	10 years
U.S. reporting unit
Goodwill
Goodwill at the end of year	$ 584,430
APAC reporting unit
Goodwill
Goodwill at the end of year	11,565
Marketing Services
Goodwill
Goodwill at the beginning of year	118,890	124,586
Impact email disposition (see note 4)		(5,684)
Change in foreign currency translation adjustment	18	(12)
Goodwill at the end of year	118,908	118,890
Marketing Services \| U.S. reporting unit
Goodwill
Goodwill at the end of year	110,910
Marketing Services \| APAC reporting unit
Goodwill
Goodwill at the end of year	7,998
Audience Solutions
Goodwill
Goodwill at the beginning of year	273,448	273,430
Purchase accounting adjustments		18
Goodwill at the end of year	273,448	273,448
Audience Solutions \| U.S. reporting unit
Goodwill
Goodwill at the end of year	273,448
Audience Solutions \| APAC reporting unit
Goodwill
Goodwill at the end of year	0
Connectivity
Goodwill
Goodwill at the beginning of year	200,393	94,729
Purchase accounting adjustments	(21)
Change in foreign currency translation adjustment	7	(6)
Goodwill at the end of year	203,639	200,393
Connectivity \| U.S. reporting unit
Goodwill
Goodwill at the end of year	200,072
Connectivity \| APAC reporting unit
Goodwill
Goodwill at the end of year	3,567
Arbor and Circulate
Goodwill
Acquisition		105,670
Arbor and Circulate \| Connectivity
Goodwill
Acquisition		$ 105,670
Pacific Data Partners LLC
Goodwill
Acquisition	3,260
Pacific Data Partners LLC \| Connectivity
Goodwill
Acquisition	$ 3,260

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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