RETIREMENT PLANS: - (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2019	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100.00%	50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%	6.00%
Defined Contribution Plan, Cost		$ 7,900	$ 2,900	$ 1,900
Liabilities of non-qualified retirement plan		11,623	14,970
Supplemental Non-Qualified Deferred Compensation Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Assets Of Non-Qualified Retirement Plan		$ 11,600
Liabilities of non-qualified retirement plan			$ 15,000