INCOME TAXES: - Reconciliation of Expected Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Computed expected income tax (benefit)	$ 223	$ 3,025	$ (7,098)
Increase (reduction) in income taxes resulting from:
State income taxes, net of federal benefit	1,203	(1,586)	(1,796)
Research and other tax credits	(5,015)	(2,285)	(4,027)
Effect of federal rate change on deferred taxes	(24,565)	0	0
Nondeductible expenses	1,028	1,156	661
Acxiom Impact disposition	0	(4,502)	0
Stock-based compensation	3,590	3,308	1,857
Non-U.S. subsidiaries taxed at other rates	246	614	2,468
Adjustment to valuation allowances	0	2,896	(3,585)
Acquisitions costs	0	478	0
Foreign income inclusion	84	473	0
Other, net	435	957	(112)
Total income tax expense (benefit)	$ (22,771)	$ 4,534	$ (11,632)