Employee Stock and Savings Plans (Tables)

12 Months Ended

Jan. 31, 2013

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Cash Proceeds Received from Share-based Payment Awards [Table Text Block]

The total intrinsic value of options exercised and cash received from options exercised was as follows:

Year ended January 31,	2013		2012		2011
Intrinsic value	$	21,647	$	15,802	$	7,812
Cash received	$	24,262	$	15,194	$	8,639

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

The following table summarizes restricted stock activity:

	Restricted Stock Units		Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Nonvested as of January 31, 2012	3,596		$	10.71
Granted	1,681		16.74
Vested	(1,162	)	10.13
Cancelled	(119	)	11.76
Nonvested as of January 31, 2013	3,996		$	13.39	1.67	$	68,453

Schedule Of Fair Value Stock Awards Vested [Table Text Block]

The following table summarizes the fair value of restricted stock vested:

Year ended January 31,	2013		2012		2011
Total fair value of restricted stock vested	$	11,698	$	5,446	$	560

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block]

The following table summarizes shares issued under the ESPPs:

Year ended January 31,	2013		2012		2011
Shares issued under the ESPPs	1,884		2,099		3,461
Cash received for the purchase of shares under the ESPPs	$	22,645	$	22,155	$	19,019
Weighted average purchase price per share	$	12.02	$	10.55	$	5.50

Summary Of The Weighted Average Grant Date Fair Value [Table Text Block]

The weighted average grant date fair values are summarized as follows:

Year ended January 31,	2013		2012		2011
Options granted	$	7.18	$	5.43	$	5.02
Restricted stock units granted	$	16.74	$	10.91	$	9.61
ESPP purchase rights	$	3.82	$	3.19	$	2.17

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The fair value calculations used the following assumptions:

Year ended January 31,	2013		2012		2011
Stock Option Plans
Risk-free interest rate	0.9% - 1.3%		1.2	%	1.4% - 2.6%
Dividend yield	0	%	0	%	0	%
Expected life (in years)	5.8 - 6.3		6.3		5.5 - 6.5
Volatility (range)	43% - 53%		53	%	50% - 55%
Volatility (weighted average)	43	%	53	%	51	%

Year ended January 31,	2013		2012		2011
Employee Stock Purchase Plans
Risk-free interest rate	0.05% - 0.15%		0.05% - 0.18%		0.2	%
Dividend yield	0	%	0	%	0	%
Expected life (in years)	0.5		0.5		0.5
Volatility (range)	33% - 43%		32% - 38%		38% - 64%
Volatility (weighted average)	39	%	35	%	40	%

Year ended January 31,	2013	2012	2011
Acquired Company Options Exchange
Risk-free interest rate	—	—	0.1% - 3.3%
Dividend yield	—	—	0	%
Expected life (in years)	—	—	0.1 - 7.7
Volatility (range)	—	—	35% - 72%
Volatility (weighted average)	—	—	60	%

Year ended January 31,	2013	2012	2011
Employee Options Exchange
Risk-free interest rate	—	—	0.2% - 2.7%
Dividend yield	—	—	0	%
Expected life (in years)	—	—	0.5 - 5.9
Volatility (range)	—	—	43% - 77%
Volatility (weighted average)	—	—	43	%

Stock Compensation Expense Recognized

The following table summarizes stock-based compensation expense included in the results of operations and the tax benefit associated with the exercise of stock options:

Year ended January 31,	2013		2012		2011
Cost of revenues:
Service and support	$	1,529	$	1,065	$	888
Operating expense:
Research and development	9,206		8,203		7,785
Marketing and selling	6,654		5,874		6,112
General and administration	6,308		6,516		5,726
Equity plan-related compensation expense	$	23,697	$	21,658	$	20,511
Tax effect of the exercise of stock options	$	266	$	—	$	—

Matching Contribution to Savings Plan [Table Text Block]

Our matching contributions to the Savings Plan were as follows:

Year ended January 31,	2013		2012		2011
Employer matching contribution	$	7,181	$	7,141	$	6,413

Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

Stock options outstanding, the weighted average exercise price, and transactions involving the stock option plans are summarized as follows:

	Options Outstanding		Weighted Average Exercise Price		Weighted Average Remaining Contractual Terms (Years)	Aggregate Intrinsic Value
Balance as of January 31, 2012	9,187		$	10.00
Granted	539		16.97
Exercised	(2,835	)	8.56
Forfeited	(34	)	6.61
Expired	(140	)	14.71
Balance as of January 31, 2013	6,717		11.08		5.24	$	40,677
Options exercisable as of January 31, 2013	5,504		10.61		4.48	35,925
Options vested as of January 31, 2013 and options expected to vest after January 31, 2013	6,717		$	11.08	5.24	$	40,677