SEGMENT INFORMATION: (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
Revenues:
Total revenues	$ 224,867	$ 223,312	$ 217,267	$ 214,801	$ 224,655	$ 221,193	$ 207,345	$ 196,895	$ 880,247	$ 850,088	$ 804,911
Gross profit:
Total gross profit	106,573	106,844	97,162	91,982	101,029	95,458	86,033	79,186	402,561	361,706	310,874
Income (loss) from operations:
Income (loss) from operations	$ (8,709)	$ 9,115	$ 7,120	$ 8,162	$ (7,764)	$ (374)	$ (2,056)	$ (2,869)	15,689	(13,063)	(32,684)
Gains, losses and other items, net									8,373	12,132	22,600
Depreciation and amortization:
Depreciation and amortization									82,690	85,463	80,447
Total depreciation and amortization									42,741	42,829	41,401
Marketing Services
Depreciation and amortization:
Depreciation and amortization									7,549	9,988	12,280
Audience Solutions
Depreciation and amortization:
Depreciation and amortization									13,286	12,909	12,652
Connectivity
Depreciation and amortization:
Depreciation and amortization									21,906	19,932	16,469
Operating segment
Revenues:
Total revenues									880,247	850,088	804,911
Gross profit:
Total gross profit									427,084	381,172	328,103
Income (loss) from operations:
Income (loss) from operations									209,193	180,671	156,256
Operating segment | Marketing Services
Revenues:
Total revenues									410,840	449,772	446,103
Gross profit:
Total gross profit									140,647	152,258	156,395
Income (loss) from operations:
Income (loss) from operations									80,622	74,371	81,247
Operating segment | Audience Solutions
Revenues:
Total revenues									322,065	297,846	303,836
Gross profit:
Total gross profit									198,185	167,715	158,386
Income (loss) from operations:
Income (loss) from operations									123,238	109,598	115,078
Operating segment | Connectivity
Revenues:
Total revenues									147,342	102,470	54,972
Gross profit:
Total gross profit									88,251	61,199	13,322
Income (loss) from operations:
Income (loss) from operations									5,333	(3,298)	(40,069)
Reconciling items
Gross profit:
Purchased intangible asset amortization									18,644	15,466	11,454
Non-cash stock compensation									5,879	2,150	1,459
Accelerated amortization										1,850	4,316
Income (loss) from operations:
Corporate expenses (principally general and administrative)									117,342	127,844	126,570
Gains, losses and other items, net									8,373	12,132	22,600
Impairment of goodwill and other assets										6,829
Purchased intangible asset amortization									18,644	15,466	11,454
Non-cash stock compensation									$ 49,145	31,463	28,316
Accelerated amortization										$ 1,850	$ 4,316