Schedule of Fixed Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017
Fixed assets:
Total cost	$ 685,378	$ 668,596
Less: accumulated depreciation and amortization	(533,383)	(508,934)
Fixed assets, net	151,995	159,662
Equipment
Fixed assets:
Total cost	164,536	159,102
Software
Fixed assets:
Total cost	314,620	304,943
Leasehold improvements
Fixed assets:
Total cost	$ 206,222	$ 204,551