Inventories (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Components of Inventories, valued using the first-in, first-out (FIFO) method
Raw materials	$ 102,651	$ 94,694
Work-in-process	127,481	115,731
Finished goods	280,647	272,793
Total	$ 510,779	$ 483,218