Schedule of Fixed Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Mar. 31, 2015
Fixed assets:
Total cost	$ 643,533	$ 626,058
Less: accumulated depreciation and amortization	(470,711)	(446,452)
Fixed assets, net	172,822	179,606
Equipment
Fixed assets:
Total cost	154,562	152,893
Software
Fixed assets:
Total cost	284,638	269,745
Leasehold improvements
Fixed assets:
Total cost	$ 204,333	$ 203,420