ACQUISITIONS: (Details) $ in Thousands						12 Months Ended
	Nov. 29, 2016 USD ($)	Nov. 22, 2016 USD ($) item	Nov. 20, 2016 USD ($)	Nov. 29, 2015 USD ($)	Jul. 01, 2014 USD ($)	Mar. 31, 2017 USD ($) item	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Business Acquisition [Line Items]
Holdback consideration transferred		$ 38,300				$ 38,300
Number of increments | item						30
Accrued purchase consideration (see Note 3 - Acquisitions)						$ 5,880
Assets acquired:
Goodwill						592,731	$ 492,745	$ 497,362
Net cash paid						137,383	5,386	265,672
Amounts of revenue and net loss
Intangible asset amortization						18,600	15,500	11,400
Non-cash stock-based compensation expense						$ 49,145	31,463	$ 28,316
Circulate Inducement Awards | All Other employees
Business Acquisition [Line Items]
Vesting period (in years)	4 years
Circulate Inducement Awards | Vesting on first anniversary on closing date | All Other employees
Business Acquisition [Line Items]
Vesting percentage	25.00%
Circulate Inducement Awards | Vesting each twelve months thereafter | All Other employees
Business Acquisition [Line Items]
Vesting percentage	25.00%
Performance stock | Vesting on first anniversary on closing date | Minimum
Business Acquisition [Line Items]
Vesting percentage						0.00%
Performance stock | Vesting on first anniversary on closing date | Maximum
Business Acquisition [Line Items]
Vesting percentage						300.00%
Arbor and Circulate
Business Acquisition [Line Items]
Aggregate fair value						$ 9,200
Assets acquired:
Cash	$ 9,495
Trade accounts receivable, net	3,352
Goodwill	105,670
Intangible assets (Other assets, net)	40,800			$ 40,800
Other current and noncurrent assets	278
Total assets acquired	159,595
Deferred income tax liabilities	(8,093)
Accounts payable and accrued expenses	(4,623)
Net assets acquired	146,879
Net cash paid	137,384
Amounts of revenue and net loss
Acquisition costs						$ 1,400
Arbor and Circulate | Minimum
Assets acquired:
Intangible assets, useful lives						1 year
Arbor and Circulate | Maximum
Assets acquired:
Intangible assets, useful lives						6 years
Arbor and Circulate | Publisher relationships
Assets acquired:
Intangible assets (Other assets, net)				$ 23,800
Intangible assets, useful lives				6 years
Arbor and Circulate | Developed technology
Assets acquired:
Intangible assets (Other assets, net)				$ 9,300
Arbor and Circulate | Developed technology | Minimum
Assets acquired:
Intangible assets, useful lives				2 years
Arbor and Circulate | Developed technology | Maximum
Assets acquired:
Intangible assets, useful lives				4 years
Arbor and Circulate | Customer relationships
Assets acquired:
Intangible assets (Other assets, net)				$ 7,100
Intangible assets, useful lives				6 years
Arbor and Circulate | Customer/Trade name
Assets acquired:
Intangible assets (Other assets, net)				$ 600
Intangible assets, useful lives				1 year
Arbor
Business Acquisition [Line Items]
Holdback consideration transferred		$ 38,300
Number of increments | item		30
Arbor | Arbor Inducement Awards
Business Acquisition [Line Items]
Grant date fair value			$ 10,400
Vesting period (in years)			3 years
Arbor | Arbor Inducement Awards | Vesting on first anniversary on closing date
Business Acquisition [Line Items]
Vesting percentage			34.00%
Arbor | Arbor Inducement Awards | Vesting each three months thereafter
Business Acquisition [Line Items]
Vesting percentage			8.25%
Circulate
Business Acquisition [Line Items]
Accrued purchase consideration (see Note 3 - Acquisitions)	$ 5,900
Period for delivering funds to the seller	1 year
Circulate | Circulate Inducement Awards
Business Acquisition [Line Items]
Grant date fair value	$ 10,000
Vesting period (in years)	2 years
Circulate | Circulate Inducement Awards | Vesting on first anniversary on closing date
Business Acquisition [Line Items]
Vesting percentage	50.00%
Circulate | Circulate Inducement Awards | Vesting each three months thereafter
Business Acquisition [Line Items]
Vesting percentage	12.50%
LiveRamp, Inc.
Assets acquired:
Cash					$ 12,016
Trade accounts receivable, net					5,206
Goodwill					213,093
Deferred income tax liabilities					(18,945)
Net assets acquired					284,666
Less: Cash acquired					12,016
Net cash paid					$ 265,672
Amounts of revenue and net loss
Revenues							27,000
Net loss							$ (16,500)
LiveRamp, Inc. | Minimum
Assets acquired:
Intangible assets, useful lives					2 years
LiveRamp, Inc. | Maximum
Assets acquired:
Intangible assets, useful lives					6 years
LiveRamp, Inc. | Customer relationships
Assets acquired:
Intangible assets, useful lives					6 years
LiveRamp, Inc. | Customer/Trade name
Assets acquired:
Intangible assets, useful lives					2 years