PROPERTY AND EQUIPMENT: (Details) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 7,000	$ 12,800
Accelerated depreciation		$ 3,600
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	44,076		$ 44,786
Less accumulated depreciation and amortization	30,555		25,465
Property and equipment, net of accumulated depreciation and amortization	13,521		19,321
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	26,058		25,614
Data processing equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	8,821		9,499
Office furniture and other equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 9,197		$ 9,673