RESTRUCTURING, IMPAIRMENT AND OTHER CHARGES: Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments	$ 1,286	$ (100)
Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments	1,300		$ 6,400	$ 8,900
Restructuring Activity2016 | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments					$ 12,000
Restructuring Activity2015 | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments						$ 21,800
Employee Severance | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments	200		3,800	3,800
Employee Severance | Restructuring Activity2016 | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments					8,600
Employee Severance | Restructuring Activity2015 | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments						13,300
Other Associate-Related Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	700
Termination Of Associates | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments			$ 2,600	3,000
Leased office facilities | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments				1,500
Adjustments to estimates related to the fiscal 2015 lease accruals | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments				1,500
Lease agreements | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments	2,300
Contract Termination | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments						6,500
Contract Termination | Restructuring Activity2016 | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments					3,000
Contract Termination | Restructuring Activity2015
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	300
Contract Termination | Restructuring Activity2015 | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments						6,500
Leasehold Improvement Write Offs | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments				$ 2,100
Leasehold Improvement Write Offs | Restructuring Activity2016 | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments					400
Leasehold Improvement Write Offs | Restructuring Activity2015 | Gains Losses And Other Items Net
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments						2,000
United States Australia Europe And Brazil | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments	100
United States Australia Europe And Brazil | Employee Severance | Restructuring Activity2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments					$ 8,600
United States Australia China And Europe | Employee Severance | Restructuring Activity2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments						$ 13,300
Restructuring reserve	$ 300