Other Financial Statements Details Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017
Accounts Receivable, Net [Abstract]
Inventory, Raw Materials, Net of Reserves	$ 16,274	$ 14,430
Inventory, Work in Process, Net of Reserves	279,192	268,281
Inventory, Finished Goods, Net of Reserves	131,377	134,491
Total inventories	$ 426,843	$ 417,202