Summary Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2012 Year	Jan. 31, 2011 Year	Jan. 31, 2010 Year
Option outstanding
Beginning Balance	11,867	18,982	20,597
Granted	517	508	970
Assumed in acquisition		2,160	285
Exercised	(2,227)	(1,640)	(259)
Forfeited	(126)	(84)	(246)
Expired	(844)	(1,114)	(2,365)
Exchanged		(6,945)
Ending Balance	9,187	11,867	18,982
Options exercisable as of January 31, 2012	7,428
Options vested as of January 31, 2012 and options expected to vest after January 31, 2012	9,187
Weighted average exercise price
Beginning Balance	$ 9.94	$ 12.98	$ 13.19
Granted	$ 10.70	$ 10.14	$ 7.90
Assumed in acquisition		$ 5.05	$ 9.19
Exercised	$ 6.82	$ 5.27	$ 7.08
Forfeited	$ 7.79	$ 7.23	$ 10.10
Expired	$ 18.38	$ 16.86	$ 13.23
Exchanged		$ 16.77
Ending Balance	$ 10.00	$ 9.94	$ 12.98
Options exercisable as of January 31, 2012	$ 10.38
Options vested as of January 31, 2012 and options expected to vest after January 31, 2012	$ 10.00
Weighted Average Remaining Contractual Term (years)
Beginning Balance	5.35	3.75	5.33
Ending Balance	5.18	5.35	3.75
Options exercisable as of January 31, 2012	4.48
Options vested as of January 31, 2012 and options expected to vest after January 31, 2012	5.18
Aggregate Intrinsic Value
Beginning Balance	$ 44,780	$ 10,347	$ 8
Ending Balance	39,303	44,780	10,347
Options exercisable as of January 31, 2012	29,647
Options vested as of January 31, 2012 and options expected to vest after January 31, 2012	$ 39,303