Stockholders' Equity - Common Shares Reserved for Issuance (Details) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Class of Stock [Line Items]
Options granted and outstanding	3,492	4,164	5,390	6,310
Employee Stock Purchase Plan	3,492	4,164	5,390	6,310
Common stock reserved for issuance	13,173
Stock Options [Member]
Class of Stock [Line Items]
Options granted and outstanding	3,492
Employee Stock Purchase Plan	3,492
Restricted Stock Units (RSUs) [Member]
Class of Stock [Line Items]
Restricted Stock Units granted and outstanding	6,444
Options and Restricted Stock Units [Member]
Class of Stock [Line Items]
Options and RSUs authorized for future grants	2,054
Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Options granted and outstanding	1,183
Employee Stock Purchase Plan	1,183