STOCKHOLDERS' EQUITY: - Other Performance (Details) $ / shares in Units, $ in Thousands				2 Months Ended	3 Months Ended	12 Months Ended
	Feb. 14, 2018 item	Nov. 29, 2016 USD ($) item	Nov. 22, 2016 item	Mar. 31, 2018 USD ($) $ / shares shares	Jun. 30, 2018 $ / shares shares	Mar. 31, 2018 USD ($) item $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Mar. 31, 2016 USD ($) $ / shares shares	Mar. 31, 2015 USD ($) shares
Share-based Activity - Other disclosures
Holdback consideration transferred		$ 38,300					$ 38,300
Number of increments | item		30
Percentage of increment over two years						3.33333%
Holdback expenses						$ 15,300	$ 5,100
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares						578,071	184,214
Non-cash stock-based compensation expense						$ 63,234	$ 49,145	$ 31,463
Other accrued expenses				$ 55,865		$ 55,865	$ 59,861
Vesting based on relevant performance period at March 31 2017
Share-based Activity - Other disclosures
Vesting percentage							9.00%
Issued (in shares) | shares							24,573
Forfeited or cancelled (in shares) | shares							260,045
Other Performance Units
Share-based compensation activity
Outstanding at the beginning of the period (in shares) | shares					111,111	597,193
Vested (in shares) | shares						(24,573)
Forfeited or cancelled (in shares) | shares						(461,509)
Outstanding at the end of the period (in shares) | shares				111,111		111,111	597,193
Share-based compensation, Weighted average fair value per share at grant date
Outstanding at the beginning of the period (in dollars per share) | $ / shares					$ 5.33	$ 4.14
Vested (in dollars per share) | $ / shares						2.94
Forfeited or cancelled (in dollars per share) | $ / shares						3.92
Outstanding at the end of the period (in dollars per share) | $ / shares				$ 5.33		$ 5.33	$ 4.14
Weighted-average remaining contractual term
Weighted-average remaining contractual term (in years)						0 days	1 year 3 months 18 days
Share-based Activity - Other disclosures
Granted (in shares) | shares								323,080	312,575
Aggregate fair value of restricted stock units granted								$ 900	$ 1,600
Outstanding (in shares) | shares							284,618
Share-based compensation expense						$ 300	$ 1,000	$ 900
Other Performance Units | Vesting based on attainment of certain revenue targets from April 1, 2014 to March 31, 2017
Share-based compensation activity
Vested (in shares) | shares									(201,464)
Share-based Activity - Other disclosures
Vesting percentage							100.00%
Other Performance Units | Vesting based on attainment of certain revenue targets from April 1, 2015 to March 31, 2018
Share-based Activity - Other disclosures
Granted (in shares) | shares									111,111
Vesting percentage							100.00%
Other Performance Units | Minimum | Vesting based on attainment of certain revenue targets from April 1, 2015 to March 31, 2018
Share-based Activity - Other disclosures
Price (in dollars per share) | $ / shares								$ 25
Other Performance Units | Maximum
Share-based Activity - Other disclosures
Performance share awards vested (as a percent)								100.00%
Other Performance Units | Maximum | Vesting based on attainment of certain revenue targets from April 1, 2014 to March 31, 2017
Share-based Activity - Other disclosures
Performance share awards vested (as a percent)									100.00%
Other Performance Units | Maximum | Vesting based on attainment of certain revenue targets from April 1, 2015 to March 31, 2018
Share-based Activity - Other disclosures
Performance share awards vested (as a percent)									100.00%
Arbor Holdback Agreement
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
2019				$ 15,300		15,300
2020				2,600		$ 2,600
Arbor
Share-based Activity - Other disclosures
Holdback consideration transferred							$ 38,300
Number of increments | item			30
Pacific Data Partners LLC
Share-based Activity - Other disclosures
Number of increments | item	4					4
Non-cash stock-based compensation expense				2,000
Other accrued expenses				1,200		$ 1,200
Annual payout, percentage	90.00%					90.00%
Performance compensation plan, trading days	20 days					20 days
End of period annual payout, percentage	10.00%					10.00%
Exercise price as a percentage of the per-share market value of the Company's shares at the date of grant	90.00%					90.00%
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
2019				15,800		$ 15,800
2020				15,700		15,700
2021				15,800		15,800
2022				$ 15,700		15,700
Pacific Data Partners LLC | Minimum
Share-based Activity - Other disclosures
Performance attainment payment						0
Pacific Data Partners LLC | Maximum
Share-based Activity - Other disclosures
Performance attainment payment						$ 65,000
Scenario, Forecast | Other Performance Units | Vesting based on attainment of certain revenue targets from April 1, 2015 to March 31, 2018
Share-based Activity - Other disclosures
Reduction in shares granted (as a percent)					59.00%