Net Loss Per Share (Details 2) In Thousands, unless otherwise specified	6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Potentially dilutive securities
Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive (in shares)	18,869	23,306
Shares subject to outstanding common stock options
Potentially dilutive securities
Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive (in shares)	14,783	22,177
Shares subject to outstanding RSUs
Potentially dilutive securities
Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive (in shares)	3,809	156
Employee stock purchase plan
Potentially dilutive securities
Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive (in shares)	277	568
Shares subject to common stock warrants
Potentially dilutive securities
Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive (in shares)	0	405