COMMITMENTS AND CONTINGENCIES - Separation Programs (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2017 Employee	Apr. 01, 2016 Employee
Restructuring Cost and Reserve [Line Items]
Named executive | Employee					2	1
Voluntary separation program
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 0	$ 590	$ 0	$ 1,468
Involuntary separation program
Restructuring Cost and Reserve [Line Items]
Severance costs	2,410	8,963	11,089	13,491
Direct cost | Voluntary separation program
Restructuring Cost and Reserve [Line Items]
Severance costs	0	590	0	1,445
Direct cost | Involuntary separation program
Restructuring Cost and Reserve [Line Items]
Severance costs	1,477	4,398	2,547	4,896
General and administrative | Voluntary separation program
Restructuring Cost and Reserve [Line Items]
Severance costs	0	0	0	23
General and administrative | Involuntary separation program
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 933	$ 4,565	$ 8,542	$ 8,595