Inventories (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Mar. 31, 2012
Components of Inventories, valued using the first-in, first-out (FIFO) method
Raw materials	$ 98,861	$ 85,116
Work-in-process	154,992	123,723
Finished goods	287,462	270,628
Inventory Net	$ 541,315	$ 479,467